Did I buy the wrong furnace?

[jeffw_00]

I have 3000 sq ft house in New England. My previous gas FHA furnace was a Coleman "high velocity" furnace. This drove a main duct that is about 1' x 3' x 12'. Off of this main are about 20 3.5" runs varying in length from 3' to 30', with most being in the 10-20' range.

I replaced it last week with a single-stage Bryant 350AAV with 4-speed fan. We have the fan cranked down to the lowest setting, and it still moves more air than my old furnace (and thus is noisier). With the current outside temps of 30-40DegF, the furnace doesn't cycle for more than a couple of minutes every 15min or so because it appears to be much more efficient at heating the house. I recognize that performance may be different when we get our few weeks of 0DegF weather, but on the other hand a lot of our winters are just like this.

The new furnace has the same 112K Output BTU as the old furnace. I recognize that the effective output BTU of my old furnace was lower, but we added about 400 sq ft of heatable space to the house since we bought it and there was some feeling that the old furnace was on the edge or slightly less than we wanted (When it was really cold out, if we had shut the heat off for a while, it could take hours for the furnace to bring the house back to temp).

All 3 contractors that quoted me recommended a single-stage furnace because they said that the lower fan speeds of a 2-stage furnace would be insufficient to drive air through the system. I raised this point a couple of times with the company that did the work (Who I'm otherwise VERY happy with), and they felt strongly that a 2-speed would be wasting my money.

However, I'm having buyers remorse. It seems like it would be more efficient, quieter, and perhaps more comfortable to have less BTU and slower fan taking longer to heat the house. (also, that would permit more runtime on my Humidifier which would also be a good thing).

I'm also concerned about this: To get more even heating, a little more hysteresis, and reduce the noise, I re-balanced the ducts, with the new effect of have them closed down a little more than before. Is it bad for the system fan to have to push the air so hard? (I think with all the ducts open there would still be some back-pressure, it's really a powerful fan).

I haven't talked to the contractor yet, because I want to try switching out the 18yr old Honeywell clock stat for a new (White-Rodgers) electronic one. I noticed that the system performance seems independent of the anticipator setting so I'm wondering if a broken stat is part of my problem. (Although the temp at the stat does stay fairly consistent).

Still, I'm posting because I have two questions:

1) For those of you who have experience with two-stage furnaces, do you think one would be good for me? What I'd like is a fan speed that pushed about 80% as much air as the lowest setting on this one. If the extra fan speeds on a 2-stage are like 50% slower, or only run in certain conditions, then it won't do me any good.

I get that a smaller furnace might be an option, but I don't want to go there until I've lived though some 0DegF nights with this one.

2) If we all agree I have the wrong furnace, what can I do about it? I don't think it's fair (or possible? ) to ask the contractor to 'eat' the furnace. Can he re-sell it? Does Bryant have a 'satisfaction guarantee'?

Thanks very much
/j

[jacob perkins]

maybe just change the blower

if you open all the dampers it might reduce the noise

[jeffw_00]

Interesting, i would have guessed that the blower was matched to the heating element and electronics. I thought about opening everything, but I still think some rooms would get too much heat (there are a number of ducts that are off or 95% off as the rooms get enough heat from adjacent (or below) spaces.
thanks.

[beenthere]

Check the temp rise over the heat exchanger.

With all those supplies closed off, or almost closed, you may be over heating the heat exchanger already.

Did the heat load come out to 112,000, or did you add a saftey factor.


You said when you turned youor old furnace off, it would take hours to catch back up.

My furnace is over sized, and when I turn it off, it takes hours to catch back up.

[sheltermonkey]

Sounds like the local contractors anr't so keen on two stage furnaces.

Funny thing happens when an old dirty blower wheel gets replaced with the furnace.

A two stage furnace seems to make sense to me when you have small ducts and are afraid of sizing the furnace too small.
Makes sense if you can afford it anywhich way.


Are those ducts accessible? How bout some bigger ducts?

[tinknocker service tech]

sounds like a two stage v drive would have been worth thinking about.

open all the outlets and put a new stat in
you have a new furnace so the balancing will need to be reajusted also.
start with full open and go from there

the anticapator may be causing the unit to short cycle since it is set up for a much older unit.

you can try to set it at .8 and see if it helps

[dan sw fl]

Originally posted by jacob perkins
just change the blower

L O L

[dan sw fl]

Originally posted by jeffw_00
I thought about opening everything, but I still think some rooms would get too much heat

(there are a number of ducts that are off
or 95% off

as the rooms get enough heat from adjacent (or below) spaces.

Nothing like creating your own mess to sleep in !

Trying to get somewhere ...
that's the same as installing a stop sign every
700 feet on a 6-lane road.


[Edited by dan sw fl on 02-01-2006 at 08:46 PM]

[jacob perkins]

-he did say he wanted less airflow,I think

[jeffw_00]

Guys - I'm glad I'm adding so much entertainment value. Most of the ducts are open 2/3 of the way or more. If I open them all, all the way, it's too noisy and some small rooms get baked. I find that the shorter the run, the more I generally close the duct (duh?) otherwise I bake the rooms closest to the furnace.

How much lower are the 'low' fan speeds in a 2-stage furnace?

And if I had a 2 stage and it went down to a low speed, would i lose so much temperature through the duct that it would defeat the purpose?

I measured the temp drop (with the old furnace) once. With 180DegF at the box over the furnace, I read 150-160 at ducts close to the furnace, and 100 at the far end of the longest run.

Again, I'm glad I'm entertaining, but if you know something that would help, please educate me so that when I talk to the contractor I entertain him a little less 8-}

/j

[t527ed]

if those temperatures are with the new furnace you have way more problems than noise. furnace is grossly oversized or ducts WAY to small

[jeffw_00]

should the new furnace be hotter or cooler? I would expect the differential to be independent of the source, and given how much less the new furnace runs, I would guess that it's putting out -hotter- air? (maybe that's the problem?)

[beenthere]

The data tad in your furnace will tell you the max allowable temp rise, look at it.

Did you add a safety factor to your heat load.

[dan sw fl]

Originally posted by jeffw_00
Guys - I'm glad I'm adding so much entertainment value.

Most of the ducts are open 2/3 of the way or more.
If I open them all, all the way, it's too noisy
and some small rooms get baked.

I find that the shorter the run, the more I generally close the duct (duh?),
otherwise I bake the rooms closest to the furnace.

I measured the temp drop (with the old furnace) once. With 180'F at the box over the furnace,
I read 150-160 at ducts close to the furnace,
and 100 at the far end of the longest run.

Sounds like you need a properly located
in-line Booster fan
for sufficient air distribution
with ALL the ducts WIDE OPEN.

Yes,
high-velocity = noise

You are ' stuck with ' the
characteristics of a High Velocity system until
the 3.5" diameter duct work is changed.
( For starters:
1. change the 10 furthest or longest runs to 5" or 6" dia.
or
2. add a ~1,000 CFM booster fan after 6 to 10 outlets
from the furnace)

#1 results in slightly less noise

Can the BRYANT furnace provide 1,400 CFM?
If not, what is the blower performance?

.... HIGH - Velocity Air Flow System

....... Q = 1.08 CFM * dt

...... 112000 BTU
...... 0.9 Efficiency
...... 100,800 BTU Output

...... 70 CFM in 3.5" Duct Air Flow at 0.6" / 100 Ft.
.......... (~1,000 FPM)
...... 20 ... Quantity of 3.5" dia. ducts
...... 1,400 .. CFM TOTAL in 3.5" dia. Ducts
...... 135'F. Supply Air
...... 70'F . Return Air
...... 65'F . dt

...... 1.08 .. constant
...... 98,280 Q ( BTUh)

MORE overall air flow
(to balance at the furthest point, at least)
is needed not less.

Yes, short cycling will likely be a problem.

[jeffw_00]

Ummm - you're saying I need MORE air-flow? Won't that bring MORE noise, and even FASTER cycling?

Why don't I want LESS air-flow to get
LESS noise
LONGER Run-times (= more humidification)

/j

[t527ed]

with temp rise you are getting you need more air flow=bigger ducts, or a smaller heater.

[jeffw_00]

The 180 temp was the -old- furnace - haven't measured it on the new one. New ducts are a very expen$ive option, will rip up the ceiling in a number of rooms, and will, in some cases yield less desirable results (ducts in the ceiling rather than in the floor). And then I'll have to downsize the furnace anyway.

[t527ed]

we need new furnace temps

[Tony0945]

Originally JeffW_00 said that his new furnace matched the 112K OUTPUT of his old furnace, but dan sw fl states that 112K is the INPUT rating of the new furnace. If the input rating was matched, I think the answer is, "Yes, you definitely bought the wrong furnace." Also, Jeff quoted a 160 degree RISE. That would put the output temperature to at least 220 degrees. I'd expect a fire to break out at any time. I think you mean 160 degree outlet temperature. What's the inlet temperature?

On this temp rise question, is your humidifier adequate? Recently my humdifier's solenoid failed. I was getting 135 degree outlet (60 degree rise, close to the rated max of 65 degrees). After the solenoid was replaced, the outlet dropped to 100 degrees (25 degree rise, the furnace's rated minimum). It takes a LOT of heat to vaporize water. Try turning the humidifier off and see what temp rise you get. If the change is minimal, your humidifier is dead or undersized.

[jeffw_00]

Both furnaces have 112K OUTPUT, fer sure. THe temp AT the old furnace was about 180, and it was about 100 at the furthest duct - that's an 80 deg drop across about 20' of main (I think i originally said 12') and 30' of 3.5" run. The humidifier is a drum type which (as I learned accidently) can make the house WAY too wet, but PROVIDED I'm getting sufficient furnace run times.

Again, my problem isn't temp drop. Lowering the furnace fan speed will solve all my -current- problems (noise, short cycles), my question is what other problems it will create. if the answer is none, then how do I get there from here?

[sheltermonkey]

One wanders what you gained by buying a new furnace.
Two years of reliability?
Is heat lost in the duct getting back into the house?
How about all that heat that goes up the flue because your temp rise is too high.
Sounds like a job my employer would do inorder to get the sale.
Good luck with all that.
Sorry to be cynical but it is what it is.

[jeffw_00]

Again - i don't know what the temp rise is with the new furnace. I will measure it. What I got in the new furnace was efficiency going from 70ish to 92%, direct venting, and no more CO (old furnace was circa 1960 and I was starting to get Co problems).

However, and I'm guessing - if the Temp rise on the new furnace wasn't similar (or even higher), how would I get sufficient heating with the short cycles?


[Edited by jeffw_00 on 02-02-2006 at 01:58 PM]

[beenthere]

Its moving more air, so it doesn't have to be as hot.

You may be over heating the new heat exchanger, which will void your warranty.

If you slow the blower down more, it will just damage the heat exchanger faster.

[jeffw_00]

Thanks been-there. Less air with the same furnace is a bad idea. I get that. But what about less air AND less heat?

My original post suggested that i might be happier with a 2-stage furnace that would blow less air and less heat much of the time. All the installers thought that, in low-speed operation, the furnace would move too LITTLE air to heat the house. But now that the single-stage furnace is installed, and it's moving so much air on it's lowest setting, I'm wondering if everyone was wrong. The problem now is that noise is more than before, and it warms the house so fast that the humidifier doesn't get much change to run.

It's possible the estimators were right because, given my small ducts, less air would now move well through the ducts, creating the heat-rise you describe. But I suspect a little (say 20%) less air would be perfect for me, as that would give less noise and lower run times. I understand I can't slow down the fan without 'shrinking' the heating element, but that's what a 2 stage does. My question is whether the reduction with a 2-stage is like 20% which would be great, or like 50% (which would be way too much).

One could suggest that what I need is a 20% smaller single stage furnace, but I'm unwilling to sign up to that until I see how this one performs when it gets really cold.

thanks!
/j

[peytonc2682]

You have too small of a duct system. Thats why is it making more noise. Higher eff. furances move more air. Have the duct system properly sized and put the blower back on the correct speed.

A 2 stage furance will always heat the house. GET A NEW CONTRACTOR!

[jeffw_00]

Thanks, I think you're right about the blower being bigger, but replacing the duct system in my 45yr old house would be a huge nightmarish project that I'm not prepared to contemplate right now, though it would be nice. (it would require opening ceilings, walls, etc). The house is a multi-level with a finished basement so there are no easy solutions here.

I like the contractor. and he may have been right. Can ANYONE please, please, tell me whether the lower speeds in a 2-stage system are, like 20% lower (good for me) or, like 50% lower (probably no good for me).

[beenthere]

Is your basement where the furnace is heated.

If not, how big is it, and have you considered heating it, that would lower the air flow upstairs.

[jeffw_00]

it's in the basement, yes

[jeffw_00]

Originally posted by peytonc2682
You have too small of a duct system. Thats why is it making more noise. Higher eff. furances move more air.

You know - everyone else (contractors, people in my neighborhood who had their replaced) have said the opposite - that with bigger ducts, todays normal furnaces move LESS air than a furnace designed for 3.5" ducts. The fact that it move MORE is not what anyone expected, and is why everyone thought a 2-stage, that would move -even less- was a non-starter.

[beenthere]

They don't move less air, the bigger ducts allow for more air to move slower. It gives people that had the 3.5" ducts the illusion that its moving less when its not.

[jacob perkins]

the temperture rise been checked? whut iz it?

[jeffw_00]

Originally posted by beenthere
They don't move less air, the bigger ducts allow for more air to move slower. It gives people that had the 3.5" ducts the illusion that its moving less when its not.



Oh.... so even a 2-stage won't move appreciably less air?
/j

(no - I haven't checked the temp rise yet, maybe tonight if I can find my oven thermometer 8-})

[beenthere]

Originally posted by jeffw_00

Originally posted by beenthere
They don't move less air, the bigger ducts allow for more air to move slower. It gives people that had the 3.5" ducts the illusion that its moving less when its not.



Oh.... so even a 2-stage won't move appreciably less air?
/j

(no - I haven't checked the temp rise yet, maybe tonight if I can find my oven thermometer 8-})

It will on first stage heat, but not second.

[jacob perkins]

aint gotta be perfectly accurate,but consistant.
I think walmarts has a 5 dollar dial thermo

thr furnace has to have so much airflow to keep it from overheating.

too little = high temperture rise
too much airflow = lower temperture rise

too much airflow is the better choice there...and noise problems are solved by turning up the radio.


"temperture rise" is the difference bettween air at the intake and air at nearest output

[jeffw_00]

Ok - I'm a certified Moron (or CFM). I just went to Bryant's site. The CFM for Heating on my furnace is 1720CFM. The CFM for the closest 2-speed furnace of about the same size (actually 7% larger) is 1770CFM on high, and 1215CFM on low - which means the low-speed would be 30% lower than what i have now.

Now - what muddies the waters a bit is that my current furnace is a 4-speed, and they only list 1 CFM for heat (Which I think is the 2nd-to-lowest speed, and I'm already on the lowest, which could be like 1600 CFM). But, it boils the question down to - given my duct system as described at the top of this post, is 1215CFM too little in any case? I suspect it is....

/j

[jacob perkins]

Originally posted by jeffw_00
given my duct system as described at the top of this post, is 1215CFM too little in any case? I suspect it is....

/j

dont know.

the temperture rise measurement will say alot about whats going on there.

i suspect that you need more airflow...and whoever it was that said to heat the basement had a good idea-let some pressure escape there

[jeffw_00]

Ok - according to my somewhat accurate oven thermometer, the air temp right over the furnace is about 155DegF

You think maybe it's short cycling because it's overheating? They said that if it overheated it would shut down and I would have to power-cycle it to get it to run again, and that's not happening

/j

TO be honest, between my heat and A/C I've had every major (and many minor) residential HVAC contractors out here in the last 6 months, and not one, best i could tell, has had any interest in doing the load calculations you guys talk about all the time. Must be a local tradition or something... (sigh)
/j

[jacob perkins]

Originally posted by jacob perkins
"temperture rise" is the difference bettween air at the intake and air at nearest output

so 155 - 70 = 85

sounds high to me

high temp rise = low airflow

[jeffw_00]

"Certified Temperature Rise Range" as per the specs is 40-70DegF.

There is a never-used fitting for a 3.5" duct (a boot with a damper) right over the box. When I open the damper and stick the oven thermometer into the boot, it reads 155DegF, when I hold it right outside it reads 140DegF.

Either way, yes - it looks like I'm near the top of the range.
Clearly I could move the fan speed from low (default for Fan-only) back up to medium-low (default for heat), but that will increase my 'velocity noise' and, I would assume, cause the system to reach temp even faster.

My first step, I think is to replace the stat with my new (just arrived today) White-Rodgers 1F97-391, and make sure the short-cycling isn't a stat problem. I know the furnace isn't -overheating- as it would shut itself down. So if I want to trade off being a little over-range on Temperature rise against lower velocity noise. I lose a little efficiency, that's all, right?

thanks - I'm learning a lot
/j

[jacob perkins]

Originally posted by jeffw_00
"Certified Temperature Rise Range" as per the specs is 40-70DegF.

furnace isn't -overheating- as it would shut itself down. So if I want to trade off being a little over-range on Temperature rise against lower velocity noise. I lose a little efficiency, that's all, right?



I just hope you are not confusing a vent cleanout with ducting


that temp.range is to keep from damaging you furnace and you want to stay within it...about the middle

also there are safety switches to shut itself down ,but that's another matter.

[jeffw_00]

You know - I asked the installer when he recommended lowering the fan speed about the effect of making the air over the furnace hotter - he said it would make the system more efficient because you're 'moving hotter air' through the ducts.

Now on one hand that does seem kind of wrong. But on the other hand - with my long 3.5" runs (and the temperature loss that goes with them, don't I -need- a higher temperature at the box so that I actually get air warmer than room temp at the far end of the runs? I wouldn't go nuts, but 150ish might be the right compromise....

/j

[peytonc2682]

Get another contractor. Moving less air makes the furance less efficent! The whole problem is an antique duct system that has a modern furance attached to it. Turning down the blower speed is not the answer to fixing that problem, if anything it will make it worse. 2 stage also will not fix it because the duct system has to be able to take 2nd stage.

Your duct system was designed for an inefficent furance.... inorder to make it work now you are going to have to get another old inefficent furance.

Just because the furance is not shutting down does not mean that it is not overheating.

[Edited by peytonc2682 on 02-02-2006 at 09:19 PM]

[jeffw_00]

you analysis may be correct, I'm not sure I know how to carry out your solution 8-}.

My first step this weekend is to replace the thermostat. Then, maybe I'll put the fan speed back to the default, crank the air back a bit in the 1 or 2 rooms where noise was really a problem, and see how it operates. My concern is that the cycles will be even shorter, providing for even less time for the humidifier.

My next step, after I've gathered this data - is to call the contractor monday. I suspect the senior guys in the office know more than the guy who did the install.

[jacob perkins]

not a wise decision for the long term

manufactures say what they want based on their combined knowledge and expertise....not smart to second guess them.

[peytonc2682]

oh some digital tstats the cycle rates can be adjusted... so that might help. Be sure that the unit does not short cycle. Longer cycles are more energy efficent.

[jacob perkins]

Originally posted by jeffw_00
lowering the fan speed about the effect of making the air over the furnace hotter -


/j

is not wise

(we are getting lost here)

[jacob perkins]

Originally posted by jeffw_00
My next step, after I've gathered this data - is to call the contractor monday. I suspect the senior guys in the office know more than the guy who did the install.

that would be a smart thing

[jeffw_00]

Originally posted by peytonc2682
oh some digital tstats the cycle rates can be adjusted... so that might help. Be sure that the unit does not short cycle. Longer cycles are more energy efficent.

yup, as I -think- I mentioned sometime in the past - one thing that makes me suspicious is that, since I put in the new system, it's operation seems totally insensitive to the anticipator setting on my old mechanical clock-thermostat. Max and min settings give the same performance. That's why I ordered a good electronic stat.

I agree that if the temp over the furnace is too high I should increase the fan speed. I'm just not sure I make the change based on my oven thermostat, as it could be wrong, and I'm concerned that i need all allowable 70DegF of temp rise to get any heat to my furthest ducts. I may wait until I can get the installer out here with some real equipment...
/j

[Chuck 999]

Give me a break, we keep going around in circles here, 90% of furnace problems are lack of properly sized duct systmes your furnace is what I can tell is oversized and undersized ductwork. The first thing I look at is the size of the ductwork and then sell a system. The furnace is like a heart and the ductwork is the arteries, what happens when when you choke those arteries, well take a guess.. lots of problems and not only on the heat side, what about the cooling side? sounds like a block of ice for an evaporator coil this summer.Anything you do to this systm will be a band aid. If someone is in the "Heating and cooling" business all you are told is air flow, air flow, airflow, and it all starts from there. I'll bet you have a hell of lot of air stratification in that house, with a proper sized sytem and ductwork the unit will move the proper amounts of air and longer thus eliminating hot and cold spots and making for more even temps throughout the home.Call that company back and have them do an analysis of the ductwork and I dont know how your doing your temp rise measurement but you should not take it directly off the plenum due to a particular amount of radiant heat coming off the heat exchanger it should always be done out of the line of site of the heat exhcanger.

[tinknocker service tech]

Originally posted by cedermechanical
Give me a break, we keep going around in circles here, 90% of furnace problems are lack of properly sized duct systmes your furnace is what I can tell is oversized and undersized ductwork. The first thing I look at is the size of the ductwork and then sell a system. The furnace is like a heart and the ductwork is the arteries, what happens when when you choke those arteries, well take a guess.. lots of problems and not only on the heat side, what about the cooling side? sounds like a block of ice for an evaporator coil this summer.Anything you do to this systm will be a band aid. If someone is in the "Heating and cooling" business all you are told is air flow, air flow, airflow, and it all starts from there. I'll bet you have a hell of lot of air stratification in that house, with a proper sized sytem and ductwork the unit will move the proper amounts of air and longer thus eliminating hot and cold spots and making for more even temps throughout the home.Call that company back and have them do an analysis of the ductwork and I dont know how your doing your temp rise measurement but you should not take it directly off the plenum due to a particular amount of radiant heat coming off the heat exchanger it should always be done out of the line of site of the heat exhcanger.


i would have to agree
you are taking five pounds of ____ and sticking it in a one pound bag and then to top it off you are putting a lid on it by closing the dampers

get a heat load done and duct evaluation done and install the correct unit and make the needed changes to the ducts
or learn to deal with the noise from the air. from what you have said in the last four pages if the only problem you are having is air noise then you are lucky

raise the speed back up and bring the unit into specs
the noise is a product of what you can afford to do at this time and you will be stuck with it like it or not

[jeffw_00]

Can't replace the ducts (too huge a project).

Please tell me more on how to do the air temp measurement

New furnace is sized for same output BTU as old system, which did work OK.

No cooling on the system.

what is "air stratification"?

Thanks
/j

[Advanced Response]

This is the exact reason why the Great Pro's on this site recommend the a detailed load calculation and a evaluation of the ductsystem done prior to equipment replacement..

I noticed you stated you had a 45 yr old unit that you thought was 80 percent efficient.. Have never seen a 45 yr old unit that was any more efficient than 65-70% or less..

Have a load calculation done by a real pro.. Or you can do one yourself at the top of the page.. Click on HVAC CALC and purchase the homeowner version.. That is the first step to determine how oversized your current furnace is.. Then a great hvac contrator needs to evaluate your ductwork to see what could be done to make it work the best it can,, if total replacement of ductwork is not an option..

Goodluck
J

This is a good reason to not blindly go by previous furnace size as new furnaces need to move more air and most older furnaces are oversized to begin with..

[jeffw_00]

All you say makes sense Advanced Response, but, FWIW, 65-70% was the guesstimate of the old furnace's efficiency. But we had added 3 rooms (~ 400sq ft) since the original furnace was added, and I had observed that when it was really cold out (<10DegF) it could take like an hour for the furnace to raise the temp by a degree. I have a feeling that I will be happy with the way things work when it gets really cold, but the 'cost' is that it doesn't work as I'd like when it's 30-40DegF outside.

thanks
/j

[Advanced Response]

That is the problem with a uninformed homeowner.. A properly sized furnace would take an hour or more to raise the temp in a house one degree if the outside temp is at or below the design temp,,, in fact a properly designed and sized furnace is meant to run constantly to maintain the design temp inside when the design temp is reached outdoors..

Your unit sounds like it was hacked--in on the amount of information you have provided.. You need to have your contractor do several things to check the furnace to see what needs to be done to get the equipment where it is properly operating and will provide many yrs of great service..
Things that should be checked:: 1.) Temp rise(in low and high stage if 2stage unit).. 2.) Return Static(After filter/before blower) 3.)Supply Static(After unit before A/C Coil) 4.) Add the two together and get a TESP and plot the static pressure on the unit fan chart... (Please note that the static pressure checks should be done in all fan modes that will operate at any give time but the most important is the highest fan speed needed)...6.) If the TESP is outside allowable limits duct changes must be done or unit must be replaced with proper size unit if current unit is oversized,, however ductwork may still need reworked..

Also more things could be checked by a contractor that properly does a room by room load calculation and tests the current cfm to each room and can determine what rooms are deficient in airflow and needs the most attention..

If these checks can't be done by your installing contractor, you may want to contact a contractor that has the ability..

If you have a problem finding a contractor to solve your problems,,, See if anyone from this website might be near you!!! As we have some great Techs on this site..

Goodluck
J

Your furnace is doomed to early retirement in a short time if your system is operating the way you state.. Furnaces are not built like tanks anymore like your 45yr old unit was..

[jeffw_00]

Thanks - is my project for next week

what is TESP?

[peytonc2682]

Sounds like your old furance was closer to the needed BTU. If it was raising temp by 1 degree per hour at -10, then it was sized about right. A properly sized unit will run constantly in extreme temperatures. If your unit cycles during these extreme conditions, it is no doubt oversized.

Have a manual J done to determine the load, needed BTU.

Have a manual D preformed to determine the set-up of your duct system.

If your contractor can not do this, CALL SOMEONE ELSE.

[Edited by peytonc2682 on 02-03-2006 at 10:30 AM]

[jeffw_00]

My plan for the weekend is to do my homework before I call my contractor. to that end - I plan to

1) nudge the fan speed up one tick back to the default, and see what that does to the air-temp above the furnace (I don't trust my oven thermometer for an absolute reading, but I suspect a relative reading will be informative).

2) with the fan at default (and perhaps also at the lower setting) - mark the current setting on all the ducts, and then open them all up all the way (exceptions: one room that's right next to the stat, one room where noise is a real issue), and see how that affects noise, cycling, and the temp over the furnace.

3) replace the stat and see what that does to the cycling. My hope is that the run times will be longer and less frequent.

Then Monday I will call the contractor, with my issues being
a) noise,
b) short run time,
c) concern about the temp over the furnace, and
d) concern about the back-pressure (static pressure?) on the system (concern is effect of c & d on furnace lifetime).

Did I miss anything?
/j

By the way - though I admit they hand-waved the sizing (and I suppose I was complicit), they are a big successful local company with a good reputation, big enough that they could afford to eat a furnace if it was clearly a mistake (can they re-use it elsewhere?) , so I'm hopeful that they will correct whatever the problem turns out to be (and Bryant does plaster a "100% satisfaction guarantee" on their website for whatever that's worth).

thanks guys
/j

PPS - So I was thinking - With the old system, I had an 80Deg temp drop from the furnace to my furthest duct, so I was afraid that if the furnace operated properly (say 60 DegF temp rise at the furnace) that there was no way to get heat out to the far ends of the small ducts. However - is this what the increased airflow is for? I mean - if the furnace moves significantly more air, do I have less temp drop across the length of the ducts?

Thanks!
j


[Edited by jeffw_00 on 02-03-2006 at 11:26 AM]

[jacob perkins]

Originally posted by jeffw_00
Interesting, i would have guessed that the blower was matched to the heating element and electronics. I thought about opening everything, but I still think some rooms would get too much heat (there are a number of ducts that are off or 95% off as the rooms get enough heat from adjacent (or below) spaces.
thanks.

a few more things that might not have been mentioned

1.Thermostat location must be carefully selected

2.It sounds like you had a "high static" system ,not a "high velocity" system.If a blower that matches the specs of the original can be found (AND keep the temperture rise in the mid-range on this furnace)then that might be a solution. Look for a high static blower,or note the difference between the old and new wheel,.... maybe try to retrofit the old wheel to the new furnace

3.the 80 degree duct loss is incredible.something needs to happen with that.

4.maybe installing 2 smaller furnaces would be better than one large.

[jeffw_00]

Thanks jacob, but I don't think I'll need to get carried away. I live in a section of town where approximately 200 houses were built around the same time, mostly with the same duct system and furnace. All the contractors I had bid had done other swap outs in the area, including the guys who got the job. I'm friendly with a couple of dozen of my neighbors and they're all reasonably happy with conventional swap outs.

It's -possible- that if I just open all the ducts things will balance out, possibly with raising the fan speed, possibly not.

I wouldn't react -too- strongly to the 80 Deg rise - i am, after all, using an oven thermometer. As i mentioned in my weekend plan, I want to see what sort of relative temp change I get from opening all the ducts, and removing the fan.

Stat is in the middle of the hallway outside the bedrooms.

Worst case the thing is over-sized, and if I can prove it I think there's a chance that the contractor and/or bryant will set things right.

we'll see. - have to do the tests.
thanks
/j

[jacob perkins]

Originally posted by jeffw_00
PPS - So I was thinking - With the old system, I had an 80Deg temp drop from the furnace to my furthest duct,

I meant that is not normal.

let us know what you find out

good luck

[jeffw_00]

yup, I get it

[jeffw_00]

Results of my testing were interesting. I tried

1) Vents in original state (many closed or partially closed), Fan at Low.

2) Open all vents, Fan at Low.
3) Open all vents, Fan at Low-Med (factory default).

In all cases, the temp at the furnace was about the same over 3-4 measurements of each case. I opened a damper on an unused 3.5" boot right over the furnace and held the oven thermometer in the airflow (but not touching) and it was about 150DegF in all 3 cases. House Temp was about 75, allowed max increase is 70DegF, so the temp at the furnace could be a bit over spec, or the thermometer could be a bit inaccurate.

The noise in #1 and #2 was about the same overall, so maybe I'll keep the vents more open. The noise in #3 was really unacceptably loud. I mean, really loud, a foreground noise rather than a background noise. If we determine that this fan speed is necessary for proper furnace operation, I will insist on a smaller furnace.

So, for whatever reason, it seems like my damper settings didn't make a lot of difference, nor did the addition/subtraction of ~200cfm (roughly 12% more air).

I'm sure both things -do- make a difference, but it's a smaller difference than I can measure with my rather coarse method.

Definitely want to get the contractor here next week to make sure the furnace is running within it's temp rise spec. However if it is, even with the ducts adjusted the way I want them and the slow fan, I'm not sure I have a problem...


Tomorrow I install the stat and see how it affects the cycling.

thanks in advance for your comments
/j

[Advanced Response]

Jeff,

We love pictures of anything you can take a picture of and also if you can take measurements of all the ductwork and let us know what size the trunkline is and how long it runs for both supply and return..With pictures and measurement someone on this site might know some suggestions..

It sounds like the duct system will be unsuitable with anysize normal furnace.. I saw that you have a attic unit that provides the cooling.. Is it possible to have heat pump installed and heat banks and do away with the current heating system/setup..

We need pics... We live for pics..
By the way if you position your hot wife in each pic you might get more attention to your problem...LOL

Good luck
J

[dan sw fl]

Originally posted by jeffw_00
Thanks - is my project for next week

what is TESP?

? Total External Static Pressure

[jeffw_00]

Hi - the return is a single 5' x 8" register, going into a larger box that's 8" x 20" in the other dimensions. It stays that size right to the furnace. The main is 8" x 28" x 20' (including the curved part leaving the top of the furnace. There are 14 3.5" ducts, 3 4" ducts off the main. I tried taking a couple of pics but I can't focus on very much at a time, and there's really nothing interesting to anyone who has seen one of these systems (which I assume you have).

Dozens of people in my part of town have done this upgrade without tearing apart their house to replace the ducts, so I know there's a right way to do it.

Adding heat to the attic is a non-starter, I think. First, in New England it can get REALLY cold, and the A/C system doesn't have any direct feeds down to the lowest levels of the house.

again, thanks- I just installed the new stat. I plan to talk to the contractor Monday, and at least have him check (with his more accurate equipment) that the box over the furnace isn't too hot. If it isn't, and if I can adjust the new stat to cycle the system more reasonably, I might call it good enough. But I've learned a lot.

thanks
/j

[jacob perkins]

Originally posted by jeffw_00
anyone who has seen one of these systems (which I assume you have).





you assume too much maybe

[jeffw_00]

It's what you picture, a main sized as I mentioned, with round ducts hanging off it attached by boots, with a damper in the round duct just after it leaves the main. The ducts disappear into the walls and ceiling, each headed for it's own register.

I could try to take a picture of the furnace and the box above it, but that's in a really small area so it may not be that enlightening.

sorry!
/j

[atphvac]

Your 20 3.5" ducts can carry about 1100cfm @ .4"water column which means the air coming out your duct terminations would be moving at around 900 feet per minute. I don't have the blower performance data for your furnace here but if it is a 4 ton blower it is only going to move about 1400 cfm at that static and if your static is higher it will move less air. Consequently your static must be much higher than .4".

If there is no possibility of redoing the ductwork properly here is an unconventional fix (band aid)we did in a home with a similar situation. THIS MUST BE DONE BY A PROFESSIONAL!! We used a zone control panel from Arzel to modulate a bypass damper which controlled the static pressure in the duct system.

In your home it would mean a (won't say size but it is critical)" duct going from the supply plenum to the farthest point you can attach it to on the return plenum. This X" duct will move 500cfm at 1500 fpm back into the return where it will mix with the return air and pre-warm it before going back to the furnace.

The zone panel also has a leaving air temp sensor which must be set to maintain the supply temp lower than the manufacturers recommended maximum temp. This LAT sensor will protect the furnace from overheating and will leave the blower running while turning the burner off when the temp goes too high and back on again when the temp drops to an acceptable range.

Now with this system in place your air balancing specialist will be able to adjust dampers to adjust airflow for even temps throughout the home and the modulating bypass will maintain the static pressure in the duct system to where your furnace blower can operate without burning out and without overheating the heat exchanger.

Caution must be taken for proper set-up because a grossly oversized furnace can short cycle to an extent that may cause condensation and damage to the exchanger. You absolutely need a duct system professional to recommend the best solution for your situation.

[Edited by atphvac on 02-04-2006 at 11:23 PM]

[jacob perkins]

Originally posted by jeffw_00
I could try to take a picture of the furnace and the box above it, but that's in a really small area so it may not be that enlightening.

sorry!
/j

I understand what you are saying,but have no experience with making it work.

atp,that was a enlightening bit of info!

[tommy graham]

I have read 6 pages of BS and atp seems to have the best fix for this problem for what is diffently a DUCT PROBLEM and something that nobody has said is all the Mickey Mousing Jeff has done with this NEW furnace could VERY EASILY VOID THE MANUFACTURES WARRENTY and then you think you have problems now. I havn't seen many of these HIGH VELOCITY Systems, but every one of them I have seen sounded like a hair dryer running, and as for your neighbors not having this problem, maybe they have just learned to live with it, cause I would just about bet they have the same problem, or maybe they could be like me and just hard of hearing








“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[AllTemp]

I also agree a properly installed by-pass damper with a capacity control would do alot for the undersized duct and over sized furance. A zone control for the capcity control isn't nessasary if you use a temperture compensating controller that uses a LAS as already mentioned.

I would use an electronic bypass damper I would not rely on a barometric to perform this task. It uses a Static Pressure Switch that can allow adjustements as needed and I find more realiable. The damper is motorized and is precisely controlled.

[atphvac]

All temp is right with regards the barometric. The Arzel uses pneumatic controlled damper and the modulating bypass control actually senses the static pressure and "floats" the damper in any position continually holding the static pressure at the setting you set on the dial. So if you close a balancing damper the bypass will open more and if you open a damper the bypass will close a bit.

[jeffw_00]

tommy g: I hope that out of the 6pages of bs you got the point that, in modern terms, my system was "high velocity" in name only. I would have never used the term if I knew what it meant today (3/8" ducts as opposed to 3.5" ducts).

I think the 6 pages may have obscured what my real problem currently is, which, thanks to the help of this forum, has changed a bit.

Currently, the noise problem is under control. I -think- the short-cycling is under control via the new thermostat (it will take a few days to be sure). The only concern is whether the -cost- of these fixes is too high a temp at the furnace. On one hand, my oven thermometer suggests that the temp at the furnace is 5-10DegF too high, but I think my precision is out-weighing my accuracy because of the primitive measuring instrument and method (any suggestions for exactly how to measure this would be appreciated). It's also interesting that increasing the air flow (by opening the ducts completely and increasing the fan speed) does not, by my limited method, reduce the air-temp at the furnace at all, suggesting perhaps that the air-temp is where the furnace wants it?

I understand a duct system matched to the furnace is a better solution. I also understand that a smaller furnace may have been a better solution (though I'd like to wait for some really cold weather to prove that. Unfortunately, this has all being going on against a background of unseasonably warm, humid weather). But if the temp in the furnace isn't too high, I'm not clear that I currently have a bad enough solution to beat up the contractor for an equipment change.

Thanks!
/j

[Tony0945]

Why in the world doesn't your contractor measure the temp rise across the furnace instead of you? Why didn't he put access holes in the ductwork for proper measurement? You can't get an accurate measurement by holding the instrument. It has to be free in the air flow. My original furnace was sub-contracted from a national builder, so you know he was the low bidder. Still, they put access holes in the supply and return plenums and checked temp rise. It's a safety and warranty matter.

Did you use a professional contractor or some guy who does it on the side? I don't understand why he didn't come to your house on Saturday and why he didn't throw a new thermostat in for "free" with the installation as is the universal custom here.

[tommy graham]

{{{{tommy g: I hope that out of the 6pages of bs you got the point that, in modern terms, my system was "high velocity" in name only. I would have never used the term if I knew what it meant today (3/8" ducts as opposed to 3.5" ducts)}}}}.




And this is where your whole problem stems from using a High Velocity duct system on a furnace that is not designed or intended to be used with this type of ducting, yes it may be a bit-h and costly to change the ducting but for the head aches you are having, with a BRAND NEW SYSTEM not to mention the cost of what you paid to replace this system and just think you have not even had the oppertunity to use this system in the cooling mode yet, what kind of problems are you gonna be faced with then?? freezing up due to low air flow, high head pressures due to low air flow, which will cause premature death of a compressor, not enough moisture removed from the air, causing high power bills and no indoor comfort?? My recomendation if you were a customer of mine would be to spend the money to replace duct system, get it over with and then you can expect the system to heat and cool your home with lower cost of operation and better indoor air quality. BOTTOM LINE is the system will nerver operate properly or efficently until the ducting is replaced


“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[jeffw_00]

1) Why hasn't the contractor measured the temp rise? I haven't discussed it with him yet, first wanted to do my own homework. I concede it's something he should have done in the installation. Where should the access hole go? (odds are I have a duct boot there). The oven thermometer is attached to a plate with the temp markings, I was holding the plate, not the glass.

2) Is it a professional contractor? Yes, it is a large locallly-run company with many trucks and a good reputation. I was impressed that as part of the bidding process I received a call from the owner (his name on the door), who seemed very technically knowledgable.

3) What will happen in the cooling season? I'll be fine, as my cooling system is in the attic and is totally separate from my heating system (I wasn't foolish enough to try to add cooling to 30' long 3.5" ducts 8-}).

4) They did offer a new stat, and probably wouldn't have charged me more, but until I discovered it wasn't working well I liked my old one and turned him down. I'd bet that if I asked him for a stat now he'd put one in, but probably not the one I picked out.

5) Why don't I just change the ducts? a) It's very costly and disruptive, requiring the tearing out of walls and ceilings. b) Many neighbors with similar houses have done this upgrade without doing the ducts, so it's hard to see how it's something i -have- to do. I've seen that, done right, this upgrade works. And, to be honest, if the contractor comes back, measures the heat rise, and, like Tommy G., says "yeah, you have a problem, only solution is to spend thousands more to replace the ducts", I'm going to be one unhappy camper for him. 8-}

thanks
/j

[jeffw_00]

Originally posted by atphvac
All temp is right with regards the barometric. The Arzel uses pneumatic controlled damper and the modulating bypass control actually senses the static pressure and "floats" the damper in any position continually holding the static pressure at the setting you set on the dial. So if you close a balancing damper the bypass will open more and if you open a damper the bypass will close a bit.

This is very interesting, it sounds like if we determine the temp over the box (and thus the pressure) is too high, a simple connect from the main to the return with the damper in it will solve the problem? Sounds like a cheap, sound solution, though, at the cost of much efficiency?

[tinknocker service tech]

for what ever it is worth
you furnace is over sized from everythig you have said here
to install a bypass to make it work correctly is a bandade imo.

why not sit down and talk to the contractor and explain to him you are not happy with the unit. imo seems you arent

if the size of the unit was your choice then be prepared to eat some of the cost for the correct unit

a unit from the 60s att 112 imput had a very small blower and was designed to just move air acroos the heatexchanger not anywhere near the push of todays units

at 90+ i would venture to guess a 100,000 three ton drive would be a better choice.

i also feel a two stage unit with v drive would be better suited here. you would run at the lower btu most of the time or in nice wheather at a set lower cfm and on high fire when it is needed at a set higher cfm. this will give more control of the air flo as long as the unit is sized properly. since this unit is just heat the amount of air isnt as much as it would be with a coil in the system
installing a furnace of the same imput btu as a 40years old unit with out a load is just plain foolish on everyones part

talk to you guy and see if something more suitable can be done

[jacob perkins]

Originally posted by jeffw_00
[ cost of much efficiency?

I would'nt think so.no
a little more electric consumption from the blower,but it would be very small cost difference.

[jeffw_00]

Thanks Tinknocker. I think if I downsized the furnace, AND went to 2-stage, the low-speed on the fan would be too low to push enough air to get to the far rooms. (think 30' 3'5" duct). I do plan to talk to the contractor. What worries me though is that the temps here in New England have been 30s and 40s for the last couple of weeks, I hate to downsize the furnace by a ton as you suggest and then, on one of our -5DegF nights, discover that I did really need the extra size. I'm not sure the oversize is so bad if I can run it with the ducts adjusted as they are now. I mean, it runs maybe 5 min out of 30 (or longer) at these temps, so I would expect my energy bills to plummet.

Yes, it looks like assuming the old furnace's output BTU was correct was foolish. Also assuming that I would need an oversized fan to compensate for the fact that my old system was "high-velocity" was also foolish.

Thanks!
/j

[jeffw_00]

Originally posted by jacob perkins

Originally posted by jeffw_00
[ cost of much efficiency?

I would'nt think so.no
a little more electric consumption from the blower,but it would be very small cost difference.

The thing I like about this is that if I learn that I need the BTUs on a -5DegF night, I can close the damper, open the ducts, and get it.

[AllTemp]

PLEASE READ

Tenp rise is the difference of the inlet return air temperture and the furnace plunum outlet temperture Supply (SA) - Return(RA) == TEMP RISE

I keep reading your taking the temp at the register a deducting the temp at the furtherst register this is all wrong...

Take a temp at the filter grill and one above the furnace if this is an upflow or below it if it is a downflow.

Please acknowledge this understanding, thank you.

[atphvac]

Originally posted by jeffw_00

Originally posted by atphvac
All temp is right with regards the barometric. The Arzel uses pneumatic controlled damper and the modulating bypass control actually senses the static pressure and "floats" the damper in any position continually holding the static pressure at the setting you set on the dial. So if you close a balancing damper the bypass will open more and if you open a damper the bypass will close a bit.

This is very interesting, it sounds like if we determine the temp over the box (and thus the pressure) is too high, a simple connect from the main to the return with the damper in it will solve the problem? Sounds like a cheap, sound solution, though, at the cost of much efficiency?

The size of the bypass is very important, the setting of the temperature sensor is critical as well as where it is installed, and actually measuring the static pressure and setting the bypass to maintain the proper static is crucial and has to be done by a knowlegable air balancing technician. Trust me if you attempt to do this yourself you will get it wrong create many more problems.

[jeffw_00]

Originally posted by AllTemp
PLEASE READ

Tenp rise is the difference of the inlet return air temperture and the furnace plunum outlet temperture Supply (SA) - Return(RA) == TEMP RISE

I keep reading your taking the temp at the register a deducting the temp at the furtherst register this is all wrong...

Take a temp at the filter grill and one above the furnace if this is an upflow or below it if it is a downflow.

Please acknowledge this understanding, thank you.

I have been measuring by opening the damper on a unused boot attached to the box immediately over the furnace, and subtracting room temp from it. Early on I mentioned that I also measured the temp at the furthest register and was concerned about the size of the drop. but the TEMP RISE I always measure over the furnace

[jeffw_00]

The size of the bypass is very important, the setting of the temperature sensor is critical as well as where it is installed, and actually measuring the static pressure and setting the bypass to maintain the proper static is crucial and has to be done by a knowlegable air balancing technician. Trust me if you attempt to do this yourself you will get it wrong create many more problems. [/B]

Agreed - never intended to do this myself.

[firecontrol]

Originally posted by jeffw_00
I have 3000 sq ft house in New England. My previous gas FHA furnace was a Coleman "high velocity" furnace. This drove a main duct that is about 1' x 3' x 12'. Off of this main are about 20 3.5" runs varying in length from 3' to 30', with most being in the 10-20' range.

I replaced it last week with a single-stage Bryant 350AAV with 4-speed fan. We have the fan cranked down to the lowest setting, and it still moves more air than my old furnace (and thus is noisier). With the current outside temps of 30-40DegF, the furnace doesn't cycle for more than a couple of minutes every 15min or so because it appears to be much more efficient at heating the house. I recognize that performance may be different when we get our few weeks of 0DegF weather, but on the other hand a lot of our winters are just like this.

The new furnace has the same 112K Output BTU as the old furnace. I recognize that the effective output BTU of my old furnace was lower, but we added about 400 sq ft of heatable space to the house since we bought it and there was some feeling that the old furnace was on the edge or slightly less than we wanted (When it was really cold out, if we had shut the heat off for a while, it could take hours for the furnace to bring the house back to temp).

All 3 contractors that quoted me recommended a single-stage furnace because they said that the lower fan speeds of a 2-stage furnace would be insufficient to drive air through the system. I raised this point a couple of times with the company that did the work (Who I'm otherwise VERY happy with), and they felt strongly that a 2-speed would be wasting my money.

However, I'm having buyers remorse. It seems like it would be more efficient, quieter, and perhaps more comfortable to have less BTU and slower fan taking longer to heat the house. (also, that would permit more runtime on my Humidifier which would also be a good thing).

I'm also concerned about this: To get more even heating, a little more hysteresis, and reduce the noise, I re-balanced the ducts, with the new effect of have them closed down a little more than before. Is it bad for the system fan to have to push the air so hard? (I think with all the ducts open there would still be some back-pressure, it's really a powerful fan).

I haven't talked to the contractor yet, because I want to try switching out the 18yr old Honeywell clock stat for a new (White-Rodgers) electronic one. I noticed that the system performance seems independent of the anticipator setting so I'm wondering if a broken stat is part of my problem. (Although the temp at the stat does stay fairly consistent).

Still, I'm posting because I have two questions:

1) For those of you who have experience with two-stage furnaces, do you think one would be good for me? What I'd like is a fan speed that pushed about 80% as much air as the lowest setting on this one. If the extra fan speeds on a 2-stage are like 50% slower, or only run in certain conditions, then it won't do me any good.

I get that a smaller furnace might be an option, but I don't want to go there until I've lived though some 0DegF nights with this one.

2) If we all agree I have the wrong furnace, what can I do about it? I don't think it's fair (or possible? ) to ask the contractor to 'eat' the furnace. Can he re-sell it? Does Bryant have a 'satisfaction guarantee'?

Thanks very much
/j






I started reading this 7 page long thread and then thought........ awwwww heck with it.

The original system being what was called a high pressure system was just that. High pressure in this instance was relating to the high STATIC pressure that the original furnaces designed for the small ductwork could overcome.
Jeff....... if none of the contractors measured the total static pressure of the ductwork then they didn't do thier job. No residential furnace that I'm aware of built today will handle over .5" of total static pressure without causing harm to the furnace.
I doubt seriously that anything you can modify, adjust, add or tweak is going to solve your problem until you replace the ductwork in your house. You might accomplish small improvements with all of the things recommended here so far, but bottom line, the warranty is already void on your new furnace because it was installed on a system that was not compatible with it.
If the original installer was doing his job correctly he would have done a full system check upon completion and taken temperature rise and total static pressure across the new furnace. I have a really strong feeling that his measurements would have told him and you that it wasn't performing within limits set by the manufacturer due to the dutwork system it was installed on.
Where you go from here is of course determined by lots of factors. Don't let the money stop you though. The money you just spent on the new furnace is being thrown away day by day never to be recovered because of the damage that is being done to the furnace.


************************************************** **********
Contractors that "assume" that a customer doesn't need something based on an assumption of ability or willingness to pay for the best job possible is doing both themselves and the customer a injustice.
In a case like this, the customer is going to pay more to get less than he would have originally.
The customer is left with a less than favorable opinion of our trade.
The contractor made less than he could have if he'd of just taken the time to do a professional job in the first place. Part of that job is educating his customer as to what he had, what he needed and how to get there.
Sad part is..... he'll be out there doing the same thing again and again because his lesson will not be to recognise a bad and dangerous situation to "cram" his equipment into, it instead will be that this guy is just another one of them whining homeowners that doesn't know nuttin about the heating trade.
************************************************** *********
Gentleman....... our business is all about the laws that govern how fluids move. Do the math and you'll never have to go back on a poorly installed or set up job.

[tommy graham]

AMEN fire control. my bussiness cards say "We Do It Right The First Time" and then Mickey ain't got to ask No questions about how it works and why it sounds like a jet engine




“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[tommy graham]

No matter what he dose with out replacing the duct work is gonna be a bandaid on a piss poor install



“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[jeffw_00]

Guys - I'm sure you have high standards, but I really have trouble accepting that replacing the duct work (which is all hidden behind skimcoat walls and ceilings in living space) is the 'only' solution. If it is, then the furnace manufacturers are missing a huge opportunity in that they're not designing units for retrofits into older duct systems. I'm more inclined to push for a smaller furnace, as it seems that would solve the problem as well?

/j

[Tony0945]

I'm confused as to your duct geometry. That long run with all the temp loss, is it in the basement? You have a 3400 sq ft two story house? Someone suggested a zoned system. I think that's a good idea. Dump the long run and put a smaller furnace at either end. Both of them 2-stage. My VS furnace works to produce a constant CFM. You can hear the blower speeding up as you close a main damper, so I don't think you want VS, unless there are constant pressure VS furnaces rather than constant flow.

The pros here will disagree with me but size the high output side for the lowest temperature you reasonably expect and size the low output for the recommended design temperature for your area. For instance, here in the Chicago area I believe the design temp is 25 degrees which is lowest daily average temperature. BUT, sometimes temps drop below zero for weeks on end and occasionly hit -20 and less in the suburbs. If I had sized my furnace for 25 degrees I would have been darn cold that day we had -2 and -10 would put me into pipe freezing range. As it is, my 2 stage variable speed unit sized as described using HVAC-CALC (none of the six companies I contacted would do a load calc, they all wanted to match my existing furnaces output) is very comfortable and is saving me some money besides. (OK, it would have saved me money if gas prices hadn't gone from 27 cents to $1.17, it is saving gas)

Buy the program. Do the calc. It took me about five hours to make all the measurements and input the data. Five hours well spent.

[jeffw_00]

The house is weird. It has roughly a 25' x 50 footprint, with 3 floors (basement, living, attic). Now, take a knife down the middle of the house (making 2 25x25 squares), and raise 1/2 the house about 5 feet. Now you have 6 half floors (from bottom to top) as follows: finished basement (actually, 1/2 finished), 4 finished living area, and an attic.

I would argue that the 50' span is too short to put a furnace on each end (and that I don't want to give up the finished living space for the 2nd furnace).

Also - it's suggested that the small/long ducts (the 30' goes from the main in the basement to living area at opposite end of the house), will be insufficient to carry heat at the 1000 - 1200 cfm of the lowest speed.

I agree that I'm concerned about downsizing my furnace too quickly. in the 3 weeks I've had it we've (in new england) had unseasonably warm weather. I also want to be prepared for the -10DegF nights we sometimes get.


thanks
/j

[jeffw_00]

FYI... I think the bottom line for now is this...

The good news is that....
1) The new stat appears to be controlling the furnace better. No short-cycling.

2) With the ducts adjusted pretty much as they were for the old furnace, and the furnace fan speed on low, the noise is not a problem.

However...
3) Since the new furnace heats the house quicker (as I think any new furnace would?) I'm not sure I'll get enough humidifier runtime when it's cold enough out to need the humidification - have to wait for some cold weather.

Still...
4) The -cost- of getting the system the way I want it may be that the temp rise at the furnace, and the air resistance of the ducts are both too high, possibly voiding the warranty and shortening the furnace life.

SO - I have a call into the contractor and will talk to him tomorrow, essentially telling him the above and suggesting that we both have an interest in the furnace running in spec. I'm going to ask that he come out and take measurements of temp rise, static pressure, cfm, etc., and see where we are.

Still, assuming the duct work doesn't change. I see only three outcomes:

1) He takes much better measurements than I did, furnace is in spec. All is well.

2) Furnace is out of spec, we make adjustments to get it in spec. (I'm thinking adjustment of fan speed and ducts, and not things like adding the controlled "loop" duct from the main to the return).

3) He downsizes the furnace, convincing me that I will still have enough BTU for those -10DegF nights

(or if we think I need the current furnace for the really cold nights, then maybe the 'loop duct' makes sense...).

Does this all seem right? are there other outcomes (other than replacing my ducts)?

Thanks!
/j

[jeffw_00]

Check this out - I discovered that my new thermostat has an interesting feature, a yellow "system calling" light that lights when it's calling for heat...UNLESS the furnace de-energizes the circuit when it shuts itself down. From there, I discovered that when the furnace shuts itself down, it tells you why (code blinked by diagnostic LED). From there, I discovered that my short-cycling was due to the furnace shutting itself down due to over-temp! Which I then discovered it did regardless of fan speed. So I thought I had the smoking gun that the furnace was too big.

Then I opened all the ducts and was unable to get the furnace to fail. EVEN on the low speed, EVEN when I closed down a few of the ducts that really can't be open all the time (one overheats a small room, another is too close to the stat), EVEN after running the heat for 20 minutes (enough to raise house temp 2DegF). Oh, and with the ducts mostly open, and the fan on low, the noise is liveable.

I suppose I could still have a static pressure problem, and perhaps the system could still be running too hot even if the furnace doesn't trip?

I don't know if I've proved the furnace is too big (because i can get it to trip by closing ducts) or that it's NOT too big, (since even on the low fan speed, it -doesn't- trip out if most of the ducts are mostly open).

Anyway, I doubt anyone would have thought to mention how the furnace trips the "operating" light on the stat, but why didn't you guys tell me that about the furnace diagnostic codes? 8-}

/j



[Edited by jeffw_00 on 02-06-2006 at 10:42 PM]

[AllTemp]

Your furnance is simply over sized and your temp rise must be above spec for the thing to be shutting off on high limit...

Your either forced to down size to match the design of your duct work or zone it utilizing a by pass system to voer come your high static pressure.
This thread has become simply ridiculous... You're either trolling the forum and getting a kick out of this or need some serious help from a proffessional contractor...

Duct design as well as your building envelope need attention!

Get your hands out of your furnace. I for one have provided enough DIY information and find the thread a waste of band width.

Good Day

[beenthere]

Originally posted by jeffw_00

[dan sw fl]

Originally posted by jeffw_00
Check this out - I discovered that my new thermostat has an interesting feature,

I suppose I could still have a static pressure problem, and perhaps the system could still be running too hot even if the furnace doesn't trip?

Anyway, I doubt anyone would have thought to mention how the furnace trips the "operating" light on the stat, but why didn't you guys tell me that about the furnace diagnostic codes? 8-}
[edited by jeffw_00 on 02-06-2006 at 10:42 PM]

Many things are SO Obvious they are left unsaid.

I, for one, assume the the poster can read a manual,
even though I know many can not.

WHY would you not know that the furnace is tripping on overheat? You can read manuals , but not comprehend this thread! !!

Check this in! ...
Small ducts = Noise = High static = Low flow = HIgh heat

[dan sw fl]

Originally posted by jeffw_00
If it is, then the furnace manufacturers are missing a huge opportunity in that they're not designing units for retrofits into older duct systems. /j

Actually, what you meant is
YOU are NOT yet AWARE of the manufacturerS who provide
the exact equipment
that is needed for your application.

It's been around for quite some time.

[jeffw_00]

No - I'm not trolling or hassling any one. Just a little slow. When I was checking temperature I didn't realize it could flag cutoff (remember, my last furnace was a relic from the pre-computer age 8-}) . So last night was the first time the furnace performed at least approximately as specified, and it ran very well. On for 5-10 min, off for ~45 minutes. Noise was acceptable, and I was even able to adjust a couple more critical dampers down without breaking anything.

I almost wish it had still shut down with all the dampers open, as then I'd have a smoking gun. Now I have to convince the contractor that, even though it works, it's so close to the edge of not working that there's still a problem. Or at least enough of a risk of a problem that he should come and do measurements. I think I can sell the latter.

wish me luck 8-}
/j

Hey Dan sw fl - what are you referring to? I though the consensus here was that the only 'right' solution was redoing the ductwork - what equipment are you referring to?

[jeffw_00]

So I called the contractor -told them I had issues with the furnace over-heating. The right guy to call me back was out on family emergency, so I'll hear back in a day or two (they would have sent someone out today if it was an emergency, but it wasn't). I took a look at the Bryant catalog. If we downsize the furnace it will be by a full ton (25%). My plan is still to get them out here to measure the temp rise and static pressure, and to calculate the heat load. might be few days though.

thanks again, I've learned a lot
/j

[jacob perkins]

Originally posted by jeffw_00
hear back in a day or two
thanks again, I've learned a lot
/j

so whats up ?

we all learn a little somethin as we go along
sometimes it is just how to make good guesses... with our eyes closed

[jeffw_00]

still waiting to hear - there is really one 'most right' guy to talk to there, and if he's out on personal leave for a couple of days I'm ok waiting until he gets to me (they actually offered to send a tech over but I want to talk to them first so that when the tech gets here he does what I want him to do)

[precision hvac]

They only have 1 guy who can help & he's on leave?
I smell a rat.
Unless you want that furnace to die soon- open all the dampers now & forget the noise or temps. Get someone out there now- even if you have to pay someone else to get it done & get some measurements. Check temp rise- and not w/ the wife's meat thermometer! And check ESP. Have a pro do it. That unit is cycling on the limit & won't be long for this world.
All this data should have been gathered during installation- not after the fact. The fact they are well known has nothing to do w/ quality. Pretty obvious here you got taken for a ride by a company who doesn't have a clue. Sizing a furnace based on the size of the existing one is pure hack.
Plus- you replaced a high static Coleman w/ a 80+ furnace. It will never work w/ those small 3 1/2" ducts.
A bipass is a band-aid. You need a properly sized furnace AND ducts. That means calcs & actual measurements, not guesswork.
Sounds like they sold you exactly what you asked for. A furnace change-out w/ no accounting for how it will work.
You say your neighbors had same work done w/o duct changes, ask them what brand furnace they have. I'd bet it's not the same as yours. If it is- they are living on borrowed time.

I would have never installed that furmnace w/o a complete bid for work. If you told me you can't afford to replace the ducts.....................
I wouldn't have done the job.

That company got a sweet deal- they took your money & have you doing diagnostics on their install! Pretty sad.
Did they pull a permit? I'd bet not.

[Advanced Response]

Precision hvac,

I could not agree with you more.. Well said..

Do it right the first time or why do it at all..

J

[tinknocker service tech]

Originally posted by precision hvac
They only have 1 guy who can help & he's on leave?
I smell a rat.
Unless you want that furnace to die soon- open all the dampers now & forget the noise or temps. Get someone out there now- even if you have to pay someone else to get it done & get some measurements. Check temp rise- and not w/ the wife's meat thermometer! And check ESP. Have a pro do it. That unit is cycling on the limit & won't be long for this world.
All this data should have been gathered during installation- not after the fact. The fact they are well known has nothing to do w/ quality. Pretty obvious here you got taken for a ride by a company who doesn't have a clue. Sizing a furnace based on the size of the existing one is pure hack.
Plus- you replaced a high static Coleman w/ a 80+ furnace. It will never work w/ those small 3 1/2" ducts.
A bipass is a band-aid. You need a properly sized furnace AND ducts. That means calcs & actual measurements, not guesswork.
Sounds like they sold you exactly what you asked for. A furnace change-out w/ no accounting for how it will work.
You say your neighbors had same work done w/o duct changes, ask them what brand furnace they have. I'd bet it's not the same as yours. If it is- they are living on borrowed time.

I would have never installed that furmnace w/o a complete bid for work. If you told me you can't afford to replace the ducts.....................
I wouldn't have done the job.

That company got a sweet deal- they took your money & have you doing diagnostics on their install! Pretty sad.
Did they pull a permit? I'd bet not.

very well put
or screw the tech get the owner out there and let him explain

[jeffw_00]

My, what a judgemental group! 8-} I didn't say they had one guy, I said they offered to send someone out, but I want to talk to their lead technical guy first, so that when they send someone out he comes prepared to do the measurements we agree need to be done (and so they send a tech who knows how to do it and not some apprentice). I could call the owner, but my sense was that their lead guy was a little more up on things, and (for reasons below) I'm not in an emergency rush. I'm sure you guys would be less inclined to cut a break for a homeowner who jumped up and down that he needed someone "today" and when you got there you found no reason for urgency.

Since I opened the dampers the furnace hasn't shut itself down once, even with the fan on low speed. In fact it's very well-behaved, and with colder temps this week I'm seeing what seems like more typical operation. Also, I've adjusted some of dampers a bit so that the noise was reasonable and it still didn't shut itself down. So as an experiment, I closed even a few more dampers to see if I was close to the edge, and I'm not, (so I re-opened those). In hindsight, I had a lot of the dampers closed or mostly closed, and the old furnace cycled off due to high temp every single day (I'm embarassed to say I thought that was how it was supposed to work 8-{), so I wonder if ANY furnace could operate with the dampers as closed as they were. Anyway, they're substantially more open now, the furnace is not on the edge of cycling off, so I don't see any short-term risk. And though I still think all the measurements could be made, a part of me wonders if that was the bulk of the problem.

Anyway, I want them to measure the temp rise, the static pressure, and do a load calc. The latter is the most important to me, because before I downsize the furnace by 25% (4-ton to 3-ton, Bryant doesn't have a 3.5 ton), I want to be -darn- sure I don't need more than 3-tons when it gets down to -10DegF here.

Anyway, give me a couple of days. I'll see this through.

/j

BTW: If there's concern that the static pressure is too high, lowering the fan speed reduces the problem, right?

[Advanced Response]

Jeff,

Your furnace is not sized on 4 or 3 ton.. That is just the highest airflow that the furnace moves for a cooling unit..
Your furnace must be size for btu output to match your heating needs..

Good luck keep us informed..
J

If they do have to put in a smaller unit,, I would recommend to check into upgrading to a variable speed 2/stage unit that is the smallest available to meet your heating needs.. And have a two stage stat installed..
We are not there to look at your situation so all advice is based on the limited information you have provided.. A competant hvac contractor that sees your situation can advise better than we can..

[jeffw_00]

Ok - maybe I was speaking out of turn, I don't really know what "ton" means. In terms of BTU and air-flow, the next smallest Bryant furnace is 25% smaller. (and the contractors used the term "4-ton" when referring to my furnace.

I appreciate the comment on the 2-speed, but if I get a smaller unit, the airflow cfm will be ~25% less. The "low-speed" for a two-speed unit will be roughly 20% less than that (again from the Bryant catalog). 60% of the current airflow -may- be problematic with the long 3'5" ducts. A 2-speed of the -same- size may be reasonable, though. We'll see.

Don't get me wrong guys, I appreciate the help and have learned a lot. But since the company may have to eat a furnace, I'm going to be a good sort who they want to help. (That's who I am anyway 8-})
/j

[precision hvac]

If they are sending techs or installers out to do installs & service- everyone of them had better have a Magnehelic & a digital temp probe on the truck. They are tools of the trade. If they don't, they are hacks. It's all part of start-up procedures.
Pick up the phone right now & demand to speak to the owner. Insist he gets his rear to your house now. Stop playing tech w/ your system & get it taken care of properly- by a trained technician who knows what the heck he's doing & what the numbers mean. Insist they run the numbers or you will hire someone who will. I can't believe how mellow you are being about this. You paid for a working system. Stop playing their game & get on the phone. The squeaky wheel gets the grease.
Where are you located?

[jeffw_00]

Maybe the squeaky wheel gets the grease in your part of the country (8-}), but here in MA we try to treat people with respect and work with them. Don't get me wrong, I intend to get this resolved to my (and your) satisfaction, but with a working temporary workaround in place I'm ok waiting a couple of days. They're not going to replace the furnace or ducts overnight anyway.
/j

[precision hvac]

Respect is earned, not given.
They are the one's who need to earn your respect.
So far- not good. They are taking advantage of your good nature.
You are the customer, don't forget that.

I am a business owner & there's no way & would let this slide for days on end. It's 8pm & I'm still at work- calling my customers from today's service.

[Advanced Response]

Jeff,
Maybe I should move!!lol
In my neck of the woods, I have to bend over backwards just to help a new customer that has a problem with a system I didn't install.. If I don't most customers would just call some hack.. Wish we had more of you in my neck of the woods..

J

Never mind.. I just noticed you are a engineer.. We normally have problems with engineers.. You must be that one of a kind engineer that fables are made of..lol

[Edited by Advanced Response on 02-08-2006 at 11:07 PM]

[jeffw_00]

Precision AC: Other than my first mention, yesterday, that I had an issue with the furnace overheating, I've kept them in the dark. I wanted to understand it totally myself first (it's my nature, I'm an engineer). They called back and offered to send someone right over. I told them no (yesterday), and asked to have the lead guy call me today. My choice. He didn't call, which I'm unhappy about, but given he was out of the office for two days I'll cut him 1 day of slack. I intend to talk to him, or the owner, tomorrow. I still can't afford the time from work to have them to the house until Monday anyway.

No evidence that they're the bad guys here. Also, with the ducts open there doesn't appear to be urgency (Unless I'm missing something). If the pressure is way too high I'll be getting a different furnace anyway.

Sorry I didn't explain it better before.
/j

Oh - and yes, they did pull a permit.

Advanced Response: I suppose because I'm an electrical engineer (computers), and do a lot of home repair and such myself (for example, I pulled the permit and wired my new kitchen myself last year), I tend to want to work -with- tradesmen rather than against them. In fact, on this job I upgraded the circuit from the breaker box and re-located some wires so they had room to run the vent.



[Edited by jeffw_00 on 02-08-2006 at 11:09 PM]

[precision hvac]

Engineer, huh?
Well, we won't hold that agains't you. :)
You seem like a good guy & a customer I'd love to have.
Remember, we are not picking on you- we are just offering help.
I see customers being taken advantage of everyday & don't want to see you join that group. That's why we may react strongly. It's pride in what we do & anger in those who perform sub-standard work.
I've been doing this since 1969. I get alot of jobs like yours that I'm called in to fix when the owner gets fed up w/ poor service or installation.
Make sure you get what you paid for & post those temp rise & ESP numbers. Insist on a copy of their worksheet.
We really want to know how it all works out!
If we didn't, we'd ignore the thread! :)

BTW- what the heck did the inspector inspect? The cancelled check? :)

[jeffw_00]

Fair enough.

The inspector looked at the furnace, asked whether the chimney got lined (it did), went outside to make sure the sign was over the exhaust and left. What more would you expect?

[tinknocker service tech]

Engineer should have known lol.
2-stage, v-drive will work wonders for ya
like your additude and more coustomers should be like you
i do want to know how it works out also

[jeffw_00]

v-drive, into this funky duct system? I thought that was the exact wrong way to go (or should -i- be lol? 8-})
/j

[Advanced Response]

Jeff,

Normal blowers are designed to operate at the designed airflow for the system up to .5 static pressure only and will loose pace(airflow) on duct systems that are too small.. So a normal blower on a bad duct system actually does not operate properly..

A variable speed blower is able to maintain the proper cfm needed to correctly operate at a higher static pressure than a normal blower.. However even with a correct size unit it will tell you if the ductwork is not designed well because it will try to push the correct airflow regardless of the ductwork.. This could show up as duct airflow noises because of the poor design of the ductwork..

The point being, a properly sized unit only works correctly with a properly designed duct system..

You are an engineer.. Why not find out what the proper size of the furnace you need yourself.. Click on the Red tab marked Hvac Calc and for a small fee you can do your own..

That is why I stated I would put in the smallest size 2/stage variable speed furnace your home requires because it will run on low stage 80% of the time which requires less cfm..

However, as I stated before duct changes may need to be done..

Your old system never operated correctly either as you stated.. Your duct system may be the culprit..

J

[jeffw_00]

Advanced Response: Thanks, good input. But the general sense I'm getting is that two-speed, or variable-speed, could make things better, but might make things worse. (Two speed might have insufficient cfm for the system, variable speed might create excessive noise). Makes me wary, I mean, if I get him to swap the furnace, The new one had better be right 8-}


ANYWAY - I talked to the contractor. They are coming next week to measure running temp, static pressure, cfm at the ducts, and do a complete heat-load calc. The guy agreed that neither one of us wants a furnace running out of spec, but compared to people here, he was less inclined to assume that the furnace could be running out of spec (hi temp or pressure) as long as it wasn't tripping out anymore.

He also said, (like you all), that given my duct work I shouldn't expect the furnace to work as well as with new duct work. I told him all I was looking for was a furnace that was running well within spec (temp, static pressure) without excessive airflow.

He's not convinced the furnace is too big yet (He wants to see the load-calc first), and, honestly, I'm not inclined to push for a smaller furnace until the heat-load calc says it's enough for the coldest nights. On the other hand, he didn't rule out replacing the furnace if that's what the measurements suggest.

The guy he is sending out was the lead installer, but now he is coming with the right instructions.

We'll see what happens.

Thanks everyone. I'll keep you posted mid-next-week.
/j

[Advanced Response]

jeff,

A variable speed blower has the capabilities to operated better on a poor duct system..To a point...(Is that ok Alltemp..).. However, if the duct system is that poor a standard blower will not work either and duct changes are needed regardless of the type blower..

However on a poor duct system no system is going to work within spec.. PERIOD.. It may be possible that a variable speed 2/stage system may operate with spec 80% of the time when the system is in low heat operation..

Your an engineer and should understand that if you have just one junk component that the whole package might operate like junk.. Your ductwork may be that junk component and any other component combined with that will make it a junk system..

Your heating system is more than the furnace,, it is a total system(ductwork/furnace/set-up/filter/design)..

I think you want us to tell you that there is a solution without replacing any ductwork or any other modification to the ducts.. Without seeing the job that is not possible.. However, your ducts sound very out of whack for any normal system except maybe a high velocity system(unico or spacepak)..

Good luck
J
P.S. I would do my own load calculation if I were you to see if they actually are doing one.. It might intrigue you to learn what is takes to figure a load calc.. Last time I checked it was like $50 for a homeowner calc.. Red Tab Hvac Calc..

[Edited by Advanced Response on 02-09-2006 at 03:57 PM]

[dash]

Originally posted by jeffw_00
Ok - maybe I was speaking out of turn, I don't really know what "ton" means. In terms of BTU and air-flow, the next smallest Bryant furnace is 25% smaller. (and the contractors used the term "4-ton" when referring to my furnace.

I appreciate the comment on the 2-speed, but if I get a smaller unit, the airflow cfm will be ~25% less. The "low-speed" for a two-speed unit will be roughly 20% less than that (again from the Bryant catalog). 60% of the current airflow -may- be problematic with the long 3'5" ducts. A 2-speed of the -same- size may be reasonable, though. We'll see.

Don't get me wrong guys, I appreciate the help and have learned a lot. But since the company may have to eat a furnace, I'm going to be a good sort who they want to help. (That's who I am anyway 8-})
/j


Smaller system ,with less cfm(air flow),should not cause a problem .Assuming the duct system was sized resonably correct the first time.

Variable speed motors can deliver the correct cfms on undersized ducts ,up to a point only.They also cost more to operate when on undersized ducts.

[jeffw_00]

Hi Dash - thanks for the input - I thought you might get sucked into this thread sooner or later 8-}

Advanced: I'm actually hoping there -is- a solution other than replacing the furnace or -replacing- the ducts. Modifying the ducts is fine with me. For replacing: every contractor who looked at the house down-thumbed duct replacement because of lousy accessibility. This guy told me he would have loved to replace the ducts but didn't see an easy way to do it.

What I meant by 'operate in spec" was "temp not so high, and system pressure not so high, that system will wear out much sooner than normal". We've already discussed some solutions:

1) smaller furnace
2) duct between main and return with damper
3) Variable-speed fan (though there's apparently some debate about whether this has cost or noise issues)
4) two-stage furnace of about the same size - Then I could keep all the ducts open and noise and air-flow would only be an issue at high speed (when assumedly I need it).

Next week we collect real data and take it from there.

Thanks all.

/j

[AllTemp]

Originally posted by Advanced Response
jeff,

A variable speed blower has the capabilities to operated better on a poor duct system..



I've been in disagreement on some of your replies ADV Responss such as the system should run all the time etc... My customers would have my butt if their systems could not bring thier homes to a comfortable set point on the hottest days... I can see this need in extreme humidity but your reply doesn't say this... Here we have hot dry summers our system have no need to de humidify...

So in rebuttal to your reply to a VS has the blower capabilities to operate better on a poor duct system... Quite the contrary they will overcome high static but caution should be used because a VS will sit and ramp up and down under high static load conditions.... The MFG specifically instruct you on use of proper duct design with these cautions... A VS will over come high static but sacrafices efficiency in doing so and in some case with extreme noise due to the high velocity it can produce at this SP .

[Advanced Response]

alltemp,

I respect your opinions and many of the posts you have made..

I live in a differant climate than you and if a system is oversized on cooling the humidity in the home will not be removed..

Are you in disagreement with Manual J to find the correct size system.. Is it not true that a properly designed system would run all day when the outdoor design temp is met and the thermostat is at indoor design temp... Now we all know that there is some fudge factor that is built into the load calculation that may allow the system to cycle off on a outdoor design day..

As far as the VS statement... If you read the whole posts not to pick and chose what to read.. I have tried to relate to the homeowner that a proper design duct system is very important no matter the blower..

Are you trying to say that a standard blower would work better in a poor design duct system than a variable speed blower.. How is that correct.. A VS is only noisy if the ducts are not capable of carrying the amount of airflow needed for the system to properly operate.. A standard blower would just be unable to try to move the correct airflow the system needed to operate correctly..

Alltemp,, Please have the respect not to pick apart my posts unless you have facts that may help the OP with their problem.. That is all I am trying to do..

Not picking a fight here,, Alltemp... But show some respect as I do respect you..

J

[jeffw_00]

As per the Bryant specs. It's 40-70DegF I will have them add a safety factor - what do you recommend.

[Advanced Response]

Jeff,

The temp rise should be set to the mid point of the range with a new clean filter... So if your temp rise range is 40-70, I would recommend you should have a temp rise of 55 degrees plus or minus 3 degrees..

As stated, this is with a clean new filter.. Your temp rise will get greater as the filter loads.. This is why it is recommended that you be in the middle..

Also on a standard blower the TESP(Total external static pressure) should be no more than .5-.6 on the speed needed to keep the correct temp rise... Even with a Variable speed unit I would not want the TESP to be more than .8 on the high heating speed or noise could be an issue or motor problems..

Good luck.. Alltemp I am sorry if I offended you..
J

[AllTemp]

Originally posted by Advanced Response
alltemp,

I respect your opinions and many of the posts you have made..



J

Sorry I may have been a bit over the top... my issue was the suggestion to accomodate a improper designed duct system with a VS system... That would be totally wrong and ignorant...

The other I address with respect to our areas..., as I stated I'm in the dry arrid climate of the Calfiornia Desert... You'd fall over backwards if you ever worked and sized AC here for our tempertures.... As I stated my customers would never allow their systems too run all day... If our systems aren't reaching setpoint and cycling we've got building envelope issues and or under sized....

Have a good one...

[jeffw_00]

Originally posted by Advanced Response
Jeff,

The temp rise should be set to the mid point of the range with a new clean filter... So if your temp rise range is 40-70, I would recommend you should have a temp rise of 55 degrees plus or minus 3 degrees..

As stated, this is with a clean new filter..
J

Thanks - that's what I'll expect. The filter is a SpaceGard 2200 (now Aprilaire) that was replaced at the beginning of the heating season. So it should be pretty clean.

/j

[xv80satisfiedcust]

This thread should be mandatory reading for any customer who is considering NOT buying 2 stage variable speed (VS).

The VS is cheaper for A/C operation 1/4 elec use (and better result w humidifier in winter?). The contractor didn't look at ducts/do load calc. My '84 Amana was 75000 btu (~60afue). The new furnace is 60,000 btu.

My biggest benefit of VS has been NO MORE DUCT HAMMERING. 2 stage means fewer temp swings. I read (on this site) that the (Trane XV80) ignitor is Silicon Nitride (?) instead of Carbide (?). Quality counts too.

[jeffw_00]

ummmm - my A/C is not part of this system. I have a separate A/C system with it's own ducts (in the attic). I don't have an opinion here, but there seem to be dissenting ones from others as to whether a VS fan is a good match for my old heating duct system

[dash]

Originally posted by jeffw_00
ummmm - my A/C is not part of this system. I have a separate A/C system with it's own ducts (in the attic). I don't have an opinion here, but there seem to be dissenting ones from others as to whether a VS fan is a good match for my old heating duct system


Bottom line is,if variable speed is not a good match,then a PSC motor won't be either.

[Advanced Response]

Dash,

Thanks for responding,, that has been my point exactly.. A VS has more static capabilities than a PSC standard blower..
However if the ductwork is in such a poor design that a VS blower will not work properly then neither will a standard blower..

J

[jeffw_00]

What does PSC mean?

[Advanced Response]

psc=permanent split capacitor motor.. Basically a standard blower system.. It is designed to deliver a certain amount of cfm at each speed tap of the multi-speed motor at a certain TESP... However a VS is able to deliver the correct cfm for the system over a greater range of TESP.. As I have stated if your ducts are in such a poor state that a VS blower will not work neither will a standard blower..

TESP=total external static pressure which is the total of the supply static(after unit before a-coil if used) and return static(after filter before blower)...

J

If the TESP is off the charts of the VS and standard blower than the only solution is to replace ductwork or change some elements of the ductwork to bring the static pressure down.. The use of a bypass from supply to return is a bandaid,, not a solution..

[Edited by Advanced Response on 02-12-2006 at 01:39 AM]

[jeffw_00]

thx

[atphvac]

When the pressure gets too high a vs blower will still try to ramp up. When the amps get to 8 the motor is toast.

[jeffw_00]

For the curious - here's where my main duct terminates and about 70% of the individual runs originate (the other 30% are at random points on the main closer to the furnace). From the point of view of the picture the furnace is about 10' behind you.

http://img106.imageshack.us/img106/3410/ducts9gs.jpg

[jeffw_00]

Now I'm getting worried - we've finally had some cold nights and my supposedly over-sized furnace is unable to cool the rooms that are furthest away. I know why. The new furnace doesn't get as hot as the old one, so the only way to carry enough heat to the furthest rooms is to increase the airflow above what it was with the old furnace, which is REALLY noisy. The solution, clearly, is more ducts to move the air from the furnace to where it's needed, but I don't see how that can be done. Even if they could fish the ducts through the existing construction, there's only 4" or so of room between the bottom of the floor joists (which are perpendicular to the direction the air has to go) and the top of the ceiling. So you would need a very wide duct with only 4" of height, and there's not much width room because all the other ducts are also in the same space.

I've heard about systems that use 3/8" air hoses - maybe I need one of those 8-}8-}8-}.

Contractor comes Tuesday, I anticipate a wide-ranging discussion.

regards
/j

[Advanced Response]

I have never heard of a unit that uses 3/8" air hoses for heating or cooling....

A unico or spacepack system uses 4 inch ducts but must be set up correctly to work.. I don't install high velocity systems so someone with experience would have to comment on what is available in a high velocity system that might accomodate your needs..

But your assumptions are probably correct that your ductwork is not capable of carrying the amount of airflow to supply the heat to the longer runs..

I hope your contractor takes some readings and does a better job the second time around than he did with the first try..

An oversized or correct size unit will not provide the btus where needed with out the proper ductwork to accomodate the unit and the needs of each room..

Good luck with your contractor..I wish you the best
J

Keep us informed..

[jeffw_00]

Thanks A/R - we'll see...

[wldbil73]

please have your contractor give you a required cfm report for each room after they do a heat load calac.
then have them do a acatual cfm reading at the regestiers in each room. btu of furnace may be correct but because of static pressuer in duct the fpm(feet per minute)of air is making to much noise by lowering fan speed you lower noise but also lower cfm of air. each room requires a certian cfm to property heat and cool that space.sorry to say you might have to live with the noise to get proper cfm to each room. contractor should have done a heat load calc from the start and checked required cfm per actual cfm for each room and total for building
lowering fpm to 700-900 is what is needed for acceptable noise levels. but in your case that would make your cfm output at your grills being fed by 3.5" ducts approx.65 cfm max.
to get a standard of 100-140 cfm from this small of a duct the fpm or velocity of air will have to be in the 1500-1700 range very noisy. sorry to have to tell you this.
possible cause of cold rooms not enough cfm of air. to correct this in your system raise the blower speed .draw back noise. possible fix add new 3.5" supply runs to cold rooms ,if there is room to feed insulated flex duct to the rooms . need a required cfm report for each room vs actual cfm output. hope this helped

[jeffw_00]

It's what I figured/expected. An outcome of the lower running temperature of furnaces compared to 45 years ago. It's tough though, because the high cfm is really quite noisy.

Thanks for putting #s on it.
/j

[wldbil73]

Originally posted by jeffw_00
It's what I figured/expected. An outcome of the lower running temperature of furnaces compared to 45 years ago. It's tough though, because the high cfm is really quite noisy.

Thanks for putting #s on it.
/j

NO PROBLEM PLEASE REPLY WITH RESULTS FROM YOUR CONTRACTOR
HOPEFULLY HE CAN FIX THE PROBLEM WITHOUT TO MUCH ADDED EXPENSE!!

[deejoe]

[QUOTE]Originally posted by Advanced Response
[B] A properly sized furnace would take an hour or more to raise the temp in a house one degree if the outside temp is at or below the design temp,,, in fact a properly designed and sized furnace is meant to run constantly to maintain the design temp inside when the design temp is reached outdoors..
************************************************** ********
here we go again,lol

With a statement such as that quote above makes me and many ,many other homeowners glad we don't have a "properly" sized furnace.lol
I just cannot imagine a furnaces' burner running constantly when down to say -4 F or even a lower
temperature.
I like them to cycle a couple of times an hour(just sufficiently enough to avoid any "swings") even when the ODT is far below that factor.
Seems to me and countless others, that some cycles per hour are easier on the equipment too, rather than this foolish continuous cycle.
Maybe by oversizing the unit perhaps 25-30% over the btu loss calculation will pay off, by avoiding this crazy idea of having a unit fire continuously at ODT,or lower.

Gotta go now, its -8 F here and I think my unit is about to come on again for its second, final 6 minute cycle for the hour.

[beenthere]

Originally posted by deejoe
[QUOTE]Originally posted by Advanced Response
[B]
************************************************** ********
here we go again,lol




Reread the OP, it all duct trouble, the new furnace is the same btu as the old one.


Your just trolling again.

[dan sw fl]

[i]Originally posted by beenthere
*********************
here we go again,lol

Reread the OP, it all duct trouble,
the new furnace is the same btu as the old one.[/B][/QUOTE]

D O U B L E Trouble =

Furnace + OP

[k c iceman]

Checking the heat rise of the furnace is going to be the first step. You need to do that as close to the furnace as possible; both supply and return. The next step would be to check the static pressure of the system. That will tell you in a hurry if there is too much air for the total duct system; a crude alternative would be to take an amp draw of the blower. If this were mine I would also see if the blower could be moved to a lower speed. Many furnaces come from the factory set on high speed.

[dan sw fl]

Originally posted by k c iceman
Checking the heat rise of the furnace is going to be the first step.

FIRST step ..
________ .... READ FULL POST! !! !!!




L O L

[jeffw_00]

Hi guys – here's an update. The contractor cancelled his visit this morning. We had a big snowstorm on Sunday and they're backed up on emergency calls, and put me off a week. I could *****, but nothing in my situation is going to change in a week, and I want them to come when they're not in a rush, and I suspect people without heat are more important right now.

Anyway – the cold weather the past few days has changed my situation, and, thanks in no small part to this thread, I'm actually close to having most of my problems solved….. Here's an update:

Problem 1: Furnace was short-cycling
Cause: Furnace was going over-temp
Solution: Open all the ducts!

Problem 2: Lots of air noise, some rooms too hot.
Solution: Partially close some ducts (but not enough to cause Problem 1).

Problem 3: Rooms at far end of duct system are cold.
Solution (new): Turn thermostat up a few degrees.
Comment: Oddly, this did NOT cause the half of the house closer to the furnace to be too warm, and yet the rooms at the far end are getting more heat because the system is running longer.

Problem 4: System is running so infrequently that humidifier isn't running sufficiently.
Solution (new): Increased airflow to humidifier, and (see #3 above) turned up thermostat.
Comment: With the thermostat turned up to the low 70s, the system is running more, and may even be moving humidity more efficiently than the old system because the ducts are more open. Anyway, it seems to be maintaining good humidity this week, which is the first week I actually need it.

Problem 5: Despite the solutions to 1-4, it is still possible that
a) The system is running too close to high temp
b) The static pressure is too high, shortening the life of the fan
c) They should have installed a 25% smaller furnace.

Solution: Contractor is coming to measure a) and b), and do a heat-load calculation.
Comment: I'm still going to do this, but I have to wonder – if they had picked up on the high-temp issue and adjusted the ducts the day the furnace was installed (solving #1 and #2 before they became problems), I wonder if we would be here, or whether I'd have just turned up the thermostat and been a happier camper. The other thing I may have done wrong, in hindsight, was to worry about furnace size, humidity, etc, when we were experiencing unseasonably warm weather (most of January and early Feb). Now that we're down in the teens, the furnace seems to be operating well, making me less inclined to believe it's significantly oversized. Still, the measurements WILL get made, and I'll let you know the results.

Problem 6: (A new fun subject for those of you with the patience to read this far): A number of years ago we added on a new garage, and converted our old 1 car garage (adjacent to the 'upper' basement) to a storage room. It's at the opposite end of the house from the furnace, and never had a heating duct run to it. The room on the same floor adjacent to the old garage had two heat feeds, so when we converted the garage, I turned one of these two feeds (one on a common wall) around to blow some hot air into the new storage room. The storge room was still coldish (66 Deg when the rest of the house was 70 Deg), but livable. HOWEVER, since I have now opened a lot of the other ducts, there is less hot air going into this room and it's getting colder (62Deg at best).

Solution??? So I was thinking. How about I put a DUCT FAN on the 3'5" feed to this room. It would suck more air from the furnace (reducing static pressure) and put it where it's needed. I know there are no 3.5" duct fans, but I did find a 4", and it wouldn't be hard to scale the duct up for the fan and then back down. Is this a good idea?

By the way. I wouldn't have made any of this progress without the help of you guys. I really appreciate it.

/j

[wldbil73]

would not worry about that room at this time
when contractor does heat load calc make sure he adds that room in then check for required cfm to acutal cfm
rember the system most likely is not providing proper air flow because of slower blower speed to reduce noise
back to earlier statment need #s to know whats going on then figure out the solution

[jeffw_00]

WLDBIL73 Yes. I agree. Yes I will get the numbers next week.

But just for conversation sake - I don't understand your assumption "the system most likely is not providing proper air flow". It's providing as much airflow as I can tolerate, and not so little that it is tripping high temp. (Hasn't tripped once since I opened the ducts). I don't want more airflow, too noisy. I don't need more airflow, I'm getting sufficient heat. If the furnace is running in spec now, life is pretty good.

thx!
/j

[Tony0945]

Solution to rooms too cold was to turn up thermostat. LOL!

[jeffw_00]

Originally posted by Tony0945
Solution to rooms too cold was to turn up thermostat. LOL!

Yeah well
1) we figured it out only a day after the posting.
2) No one here suggested it. 8-}
3) It was a bit counter-intuitive because most of the house was comfortable, I'm not sure why the part of the house closer to the furnace isn't too warm now.

Sometimes life's problems have easy answers... 8-}

[tinknocker service tech]

if you decide to keep this furnace there are a few options still open for you

1= put a couple outlets in the basemant this will help keep the floor warm above it

2= run an outlet to the spare room and conect the one you removed back to the room it was taken from

this will help reduce the static presure alow you to raise the speed and may cut down on the noise

[jeffw_00]

tinknocker - good well-intentioned thoughts. My problem though is that my house is a "multi'" (Think a split level with a basement under the living room). The 1/2 of the house over the real basement is warm as this is where the furnace is, it's the far end of the other 1/2 of the house where the colder rooms are. Because the lowest level of that 1/2 is fully finished, running more feeds into it is very difficult at best (also, it's 1960 construction, and there isn't much room to run anything). I was thinking a duct fan has the same effect as you suggest - pushing more air where it's needed and reducing the status pressure, but has the advantage of being doable.

/thanks
/j

[tinknocker service tech]

from what you just discribed and from your picture of the duct i see your point

[Advanced Response]

Jeff,

Until you have:

1.) Room by room load calc.
2.) Cfm needed for each room based on load calc.
3.) Current return static
4.) Current supply static
5.) Current TESP(total of supply and return)
6.) Current cfm going to each room as it is,, this can be obtained with a Balometer or transverse of the vent..
7.) Current temp rise..
8.) And any other readings your contractor can do for you..

It is impossible to direct you to a possible bandaid for your poor duct design..

It is possible that your return is on the shy side also and it could be upsized to obtain more airflow availble for your system but none of us are there and it would be foolish to advise with out having some numbers or being there..

As far as a booster fan,, most will not greatly add airflow to the duct that they are hooked to.. Also it is possible that it will make that run noisy if it does.. Fantech makes some decent inline fans..

Get them out there and let us know at least the 7 things I listed..

Goodluck again.. But with out the readings we are beating a suicidal furnace..
J

[jeffw_00]

Agreed. But for completeness, the nice thing about the duct fan solution here is that it's the rare room where noise isn't an issue. 8-}

[davidr]

Originally posted by Advanced Response
Jeff,

Until you have:

1.) Room by room load calc.
2.) Cfm needed for each room based on load calc.
3.) Current return static
4.) Current supply static
5.) Current TESP(total of supply and return)
6.) Current cfm going to each room as it is,, this can be obtained with a Balometer or transverse of the vent..
7.) Current temp rise..
8.) And any other readings your contractor can do for you..

It is impossible to direct you to a possible bandaid for your poor duct design..

It is possible that your return is on the shy side also and it could be upsized to obtain more airflow availble for your system but none of us are there and it would be foolish to advise with out having some numbers or being there..

As far as a booster fan,, most will not greatly add airflow to the duct that they are hooked to.. Also it is possible that it will make that run noisy if it does.. Fantech makes some decent inline fans..

Get them out there and let us know at least the 7 things I listed..

Goodluck again.. But with out the readings we are beating a suicidal furnace..
J


This is excellent advice, great post!

[beenthere]

Bet when he does a load calc on it, he'll find the furnace is over sized.

And with the right size furnace, the run time will be long enough that you don't need to turn the stat up higher.

this is of course all a guess from my chair.

Thanks for the update.

[jeffw_00]

Been there - I don't disagree. I would, however, tend to disagree if you said "33% oversized", and since the next smallest choice is 25% smaller, that might leave me with what I have...

[beenthere]

Is your furnace a 120,000 94%, or a 125,000 90%.

The next size down should only be about 20% smaller.

What brand is your furnace again.

[jeffw_00]

113K Bryant 350AA Legacy 92% plus. Essentially it's a '4-ton', and the next one down is a '3-ton'. I can get one with the same cfm and 94K BTU, or one with a ~ 25% slower blower and 94K btu. I was looking at fan speeds, which go from 1720cfm to 1315cfm (a bit drop given my system). By BTU it's only 17% smaller, but I feel like there's a bit of specmanship going on there. 20% is probably closer. Still, that's quite a step down.

/j

[beenthere]

Originally posted by jeffw_00
113K Bryant 350AA Legacy 92% plus. Essentially it's a '4-ton', and the next one down is a '3-ton'. I can get one with the same cfm and 94K BTU, or one with a ~ 25% slower blower and 94K btu. I was looking at fan speeds, which go from 1720cfm to 1315cfm (a bit drop given my system). By BTU it's only 17% smaller, but I feel like there's a bit of specmanship going on there. 20% is probably closer. Still, that's quite a step down.

/j

Your current furnace isn't moving 1720 with that high static pressure.
You were moving less the 1300 to shut down on high limit.

The 3 ton drive may be able move almost as much air as your 4 ton in your duct system.

Your installer can measure the esp, and tell you how much air it is really moving, and then check the chart of the smaller unit and tell you how close it will be to youor current rate.

From there he can tell if the next size down will work.
Might be only 10% less air.

It would even be a little less loud.

[jeffw_00]

been there - excellent point, thanks!

[jeffnette]

are we there yet?

[jeffw_00]

The contractor stopped by this morning. He took these furnace measurements:

In: 84.6DegF (intake is warmed a bit by air from humidifier)

Out 176.4DegF

Limit Switch spec: 220DegF

So, originally, I was quite out of spec tripping the limit switch. The current rise is 90 Deg, wiith 45DegF margin from the limit switch. Now, the "Certified Temperature Rise Range" in the product spec says 40-70DegF, and my measured rise is 90DegF (are they the same thing?) But I'm not sure I want my rise much lower than 90 because I need the extra rise to get heat out to the far ducts without excessive CFM. I mean, if I'm 45 DegF below the limit switch, could the temp be doing the system any harm?

RE: CFM, Static Pressure, Heat Load: The contractor left with a detailed house plan. They're going to do a heat load measurement there and then come back with their CFM measuring machine (they only have one, apparently). The idea was that after the heat load was done, they could use the CFM-measuring-machine to balance each room to the same CFM at the same time they took the measurements.

I did explain there are reasons (noise, room-size) why I don't want the same CFM in each room. Still, the tech agreed that it was a very good idea to measure the CFM of the system to see if it was oversized. So they will be back to do that (so they say) in a couple of days, after they calculate the heat load on the computer.

Stay Tuned
/j

[t527ed]

temp rise should NEVER be above spec. furnace life will be shortened at the rise you are at now.

[jeffw_00]

Originally posted by t527ed
temp rise should NEVER be above spec. furnace life will be shortened at the rise you are at now.

Well - the temp rise is above some spec I pulled out of some data sheet, but with the limit switch set so high I have to wonder if I'm reading the right spec - even for this furnace, slightly different sizes of this furnace have temp rises from 50 - 80 DegF, so I have to wonder if the hard 220DegF limit isn't more telling (and if I was at 210 i'd be worried, but 45DegF under the limit seems like a lot of margin?) I make this point because I've measured an 70-80Deg drop to my furthest ducts. So with only, say, a 60Deg rise, I won't heat the far rooms.

Also - what do you mean by shortened? If I have to trade off replacing an assembly (even at a cost of hundreds of dollars) after 10 years against not having enough rise to heat my house (or the far more expensive duct system replacement (see the photo a few pages back), I might be ok with it.

on the other hand, if they find the furnace is putting out too much CFM, and replace it with a smaller one, the temp rise will probably drop anyway - (but how will it heat the furthest rooms?).

Thanks
/j

[Edited by jeffw_00 on 02-22-2006 at 11:06 AM]

[Advanced Response]

Ed is correct...

The manufacturer gives a temp rise range so the installer can make sure the temp rise is in the middle of that range so as the filter loads, the temp rise will not excide the max temp rise with a moderately dirty filter(properly designed)...

With the temp rise at 90 degrees that is 20 degrees over the max temp rise of 70 with no room for the filter loading and restricting some airflow.. It is recommended to be in the middle of the temp rise range!!!

You company sounds like they are flying by the seat of their pants.. I can tell you your system is not moving the airflow needed and your currecnt system is oversized for the ductwork it is connected to..

Did they take any static pressure readings?? This would tell them some key information about the system..

With the information you have stated,,, I would recommend doing your own load calculation... Then you can compare your calculation to theirs and see if they actually did the calculation atall or acurately.. It is very easy to do your own with HVAC CAlc homeowner version, just click the red tab.. Cheap price too for the valuable information you need..

I hope your company figures it out,, but not much faith given what you have stated..

Your system will not last operating outside of the design parameters of the manufacturer.. how long who knows.. I have seen abused unit last 2yrs and some that lasted 8yrs but many more repairs than a properly installed system.. The heat exchanger metal is being stressed to its limit and that can be a possible safety concern if the heat exchanger opens up right to emit flue gases in the home(not likely but anything is possible)..

Goodluck
J

[Edited by Advanced Response on 02-22-2006 at 11:11 AM]

[jeffw_00]

AR: The manufacturer gives a temp rise range so the installer can make sure the temp rise is in the middle of that range so as the filter loads, the temp rise will not excide the max temp rise with a moderately dirty filter(properly designed)...

ME: If I drop my temp rise from 90 to, say, 55 DegF, the furnace will be happy, but I will get no temp rise to half my house. Is this really a good solution?

AR: Did they take any static pressure readings?? This would tell them some key information about the system..

ME: next visit - They sounded like they would infer the pressure from the CFM readings? They apparently have a really nifty CFM measurer.

AR: With the information you have stated,,, I would recommend doing your own load calculation.

ME: I started to use the program you recommend, but it seems to want me to measure every wall in every room (over 15 of them). Need to find the time to do it...

AR: I hope your company figures it out,, but not much faith given what you have stated..

ME: Give them a chance. I believe the expertise IS in the company, it's a question of getting their attention. I got the feeling from the tech today that the heat rise WILL get their attention.

AR: Your system will not last operating outside of the design parameters of the manufacturer..

ME: What will happen? Will the heat-exchanger wear out? Is that an expensive replacement? I need to trade the cost against the cost of tearing up my house to improve the ducts, or the cost of chilly bedrooms.

ME: I will keep you all posted. Be assured that I understand what you think I need to do, and I agree.

/j

Thanks!
/j

[Advanced Response]

Jeff,

The heat exchanger is not a cheap thing to have replaced.. It should have a 20yr or lifetime warranty on the part itself not including labor.. However if the manufacturer recieves a defective HE early in life or recieves one every five yrs or less,,, That manufacturer may investigate to see if the unit is not well installed or not according to manufacturer recommendations and then deny any future HE replacements..

Things that can go bad in your situation:
1.) Shortened Heat exchanger life
2.) Shortened Blower motor life
3.) Shortened inducer motor life(from excessive heat build up)
Etc,etc..Parts parts parts over and over are possible..
Mucho money.. Pay me now or pay me later..

As far as the farther ductruns,, there may be no other correction other than more duct runs or upsize of the runs.. This is a ductwork design issue not a furnace problem..

J

[jeffw_00]

Thanks AR - sounds like I'm getting between a rock and a hard place. You saw the picture, not sure we can jam any more ducts into that space, and that's the only way out of the basement. 8-{

[tommy graham]

I can't beleive this thread, 14 pages long, 22 days since the first post, and we still have the same problem...Jeff stick to designing Bathrooms and leave the Heating & Air alone. Find you another contractor and get this thing fixed. Any thing you do short of replacing the duct system is gonna be a bandaid on a brand new furnace. I can see now that you are heading towards a Black Hole of wasted time, wasted money, and piss poor performance from a high effeceint furnace in an applacation that it was never designed to operate in. You mention in previous pages that you have a seperate system for Air conditioning, is that system installed properly???, convert it from air only to heat & air, Problem Solved. I wish I had customers like yourself, write me a check for a couple grand or more and then they try to figure out what the problem with a brand new furnace is, while I'm out spending all that money...A TRUELY GREAT CUSTOMER



“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[jeffw_00]

Thanks Tommy. I haven't written a check to my contractor for anything additional, nor do I plan to, nor has he asked. Did you look at the photo I posted? Please come to my house and if you can see a way to replace the ducts for less than several thousand dollars (and the inconvenience of ripping up half my house), you're smarter than the half-dozen guys who have looked at it so far. Most people in my neighborhood have replaced their furnace, withOUT duct replacement, and there are no horror stories I've heard about systems burning out prematurely, so there is some right way to do this (all the houses have about the same floorplan and were built at the same time with the same systems. (In fact, some have the same duct system and furnace size I do). As far as the time factor - explain to me again why I'm in a rush? And why I should get priority over emergency calls?

Adding something to the attic system has been discussed, but isn't great for heat since the ducts are in the ceilings and
extend to only one room on the lower two levels. (It's New England, we need serious heat).

thanks
/j

[t527ed]

your 176 outlet temp is up in the plenumn. what is the temp down at the limit with exposure to radiant heat from hx? duct system or heater must be replaced to get in spec.


you have had plenty of good advise over the last 3 weeks if problem is not corrected you will be back a few years from now asking why did my hx go bad already....... or worse.

[tommy graham]

Jeff if you did'nt leave a 1000 miles away I promise I would come fix that thing for you, I LOVE PROVING OTHERS WRONG, trust me I do. There is always a way to do something you just have to think outside the box



“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[jeffw_00]

1) Good point about the distance differential between the measurement and limit switch - probably about 2-3'.

2) Don't dis the contractor yet, today is the first day he is getting proof that the system is running out of spec. he knows I know it's not in spec, and ultimately I dount he wants me to tell Bryant that he's leaving me with a furnace not in spec - though I doubt it will ever come to that. Let's see what he comes back with.

3) I guess the hard fact that there is proof of a problem has me thinking. Try this on... IF I tear down, (and probably replace with a slightly lower drop ceiling) the ceiling in a bathroom and adjacent laundry room, I will provide access to the space where many of the existing ducts travel through the house (the next room is a storage room where ducts are already exposed just below the ceiling). It's possible I could then replace the portion of the ducts along this main runway with a large single rectangular duct that then would run through the entire house. I would still have 3.5" runs to most the individual registers (except for those few over where the new main would be), replacing the 15' 3.5" runs that extend to the front 1/2 of the house is a much bigger task), but no run would be more than 15', and many would be just a few feet (with another group at 10-12'). Can I assume that replacing 30' or so of individual parallel ducts with a larger single rectangular duct will reduce the temperature drop through the ducts as much as 35DegF, as well as the static pressure?. This is a reasonably painless (though not costless) solution, as only the ceilings of two small rooms are affected....

Trying to think out of the box 8-}
/j

[Edited by jeffw_00 on 02-22-2006 at 02:02 PM]

[tommy graham]

There you go, it aint as hard as you think to get out of the box. There is always a solution to a problem if you just look at for the other side, and what you are thinking about is only a couple of hundred bucks verses a couple thousand. And it seems to me reading all the posts that you posted, that you could very easily do the drop ceiling yourself, once you get those ceiling out you can probally fish some bigger ductwork to the other spots also, how about closets, got any of those that line up?? use a courner of a closet to get some duct work to other spots. Use flex and it's fairly simple to fish and it's insulated also, keeps air temp up. I would just about bet your neighbors are having some of these same problems that you are having and just not as smart as your are and don't realize that they have any problems, thats why you haven't heard of any. Think about this if you get screwed by someone on a job are you gonna go tell everybody??? Some will & some won't. If they know you are an engineer I would bet they would'nt say a word, don't want to look stupid to your neighbor, know what I mean.....


“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[jeffw_00]

1) no closets, above the space i describe are 2 more bathrooms

2) couple of hundred bucks? What part of the country are you from? I'm guessing I could get the drop ceilings done for $500-$600 (a couple of days work for 2 guys), and then there's the duct work - probably also a couple of days work for HVAC tradesmen (got to run a main up a wall for 1/2 a floor, and then 30' over the 3 rooms, and then hook up 8 runs to it) - probably over $1000, though perhaps my existing guy will give me a break...

3) Big question - is it good enough? Not clear to me that it is....

[tommy graham]

Wait a minute this guy comes to your house sells you a 90+ furnace, you have problems with said furnace, says that he can install it and warrenty it, with no modifacations and you think you should pay??? Now if he told you up front that you needed modifacations for proper operation, then open the pocket book, but if he didn't say that, then that is his problem, he should have done a better job of looking everything over and sold you something for your specific applacation, if he didn't know what you needed then he should have asked for help from somebody higher up the food chain, and I said that you could install the drop ceiling not pay somebody. Now you know by what you have posted, that you and the installing company know you have a problem and with out replacing some of that duct work, you or they are not going to correct the problem unless they replace the furnace with a different type, and then still I think you are still gonna be in the same fix. And I still think that with you doing some of this labor,ie. removing ceiling & reinstalling the ceiling, that they will probally replace some of the duct work with out further charge to you, and you are Right I bet they don't say anything to Bryant about your problem....




“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[beenthere]

Jeff, your confusing max temp rise, with max discharge air temp.
They are 2 different things.

If your heat exchanger cranks from over heating, your warranty could be denied, and you end up paying for a new heat exchanger plus labor, and no warranty on the new HE. That ould happen in 3 years or less.

With a smaller furnace moving less air, you can throttle back some of the closer supplies without the loud noise.


At the temp rise they measured at 112,000 btu output, your only moving 1129 CFM!

A 105,000 output would be 86° rise at that same CFM.



Also, your temp loss in the longest supplies may be far less then you measured, since the temp check you did with your oven thermometer was off by so much at the furnace.

You need to have the manual J done to know what size furnace your house really needs, then the system can be balanced out to heat all the rooms.

[jeffw_00]

Hi Been There - good points as always.

The oven thermometer was a hack, but I felt there was some validity to -relative- readings (i.e., 2 readings on the same thermometer 80DegF apart were, in reality, at least 70DegF apart), that's where I get my sense for temperature drop across the ducts. (tonite I'll take one of my electronic household thermometers and measure the temp at the duct at the furthest room, i -think- it will be in range of the thermometer).

What is the difference between max temp rise and max discharge air temp? Which did he measure, which is being spec'd in the docs?

Do you think my partial-main-duct-replacement idea (#3 above) has any merit?

Thanks!
/j

[beenthere]

He measured temp rise, which should have been done when it ws installed, but I won't bust on them too much for not doing it.

Max discharge temp, means that no matter how low of a temp rise you had, if the discharge was any higher the HE would be over heating.

The salesman for your hvac company screwed up, it happens, they seem to be interested in making it right.

Don't make them second guess them selves by stressing too much about the temp not being as high at the longest runs, that can be overcome by increasing volume to them, and decreasing to the closer/warmer rooms, once the right size unit is installed.

Your idea about changing the supply trunk may help alot.
Exspecially with the right size furnace.

Don't ignore the return though. Its just as important as the supply The better the return, the more air you can push through the supply.

[dash]

Smaller furnace less cfms,less cfms in the same duct system will reuce the static,and deliver more air to the farthest runs than you currently get.

This may solve the problem ,unless the farthest runs are undersized a lot more than the closer ones.

PDx=PD1 X(cfmx/cfm1)squared

PDx=.3 X(1200/1600) squared

PDx=.3 X(.5625)


.16875 is the new PD

So reducing the cfms on the example ,reduced the PD or static by almost half.The fan now has the static to move the air farther in greater proportional quantity ,to the farthest runs.

[davidr]

Don't you just love those fan laws? :)

[jeffw_00]

Bd, Dash - thanks - good advice all. The only thing I might stress about, though, is I don't want them to solve the problem by increasing the cfms. It's the easy way out, but the ducts are already noiser than they were with the original system, and are noisy as we can handle. I upped the fan speed as an experiment and even after a few hours my wife and I agreed it was WAY too noisy.

So if cfm is maxed out now, I need to shrink my heat exchanger (i.e., BTU) to lower the plenum temp with the current CFM. Then, I need to reduce my effective duct length to raise the temps at the end of the runs (i.e., extend the main). Is there a better way?

(Even if there isn't, I think it's better to let them find their way to this conclusion rather than push it down their throats.

thanks
/j

LATE NEWS: I measured temp at furthest register using Radio Shack digital thermometer. topped out at ~ 110DegF. Still, if I drop the plenum 35 Deg (from 90 to 55), that gives me almost room temp (75Deg) at the register.

[Edited by jeffw_00 on 02-22-2006 at 10:35 PM]

[beenthere]

It won't work quite that way, as far as the temp dropping like you think it will.

[dash]

Originally posted by jeffw_00
Bd, Dash - thanks - good advice all. The only thing I might stress about, though, is I don't want them to solve the problem by increasing the cfms. It's the easy way out, but the ducts are already noiser than they were with the original system, and are noisy as we can handle. I upped the fan speed as an experiment and even after a few hours my wife and I agreed it was WAY too noisy.

So if cfm is maxed out now, I need to shrink my heat exchanger (i.e., BTU) to lower the plenum temp with the current CFM. Then, I need to reduce my effective duct length to raise the temps at the end of the runs (i.e., extend the main). Is there a better way?

(Even if there isn't, I think it's better to let them find their way to this conclusion rather than push it down their throats.

thanks
/j

LATE NEWS: I measured temp at furthest register using Radio Shack digital thermometer. topped out at ~ 110DegF. Still, if I drop the plenum 35 Deg (from 90 to 55), that gives me almost room temp (75Deg) at the register.

[Edited by jeffw_00 on 02-22-2006 at 10:35 PM]


IF, and it sounds like it is,your furnace is oversized ,going with a smaller one will solve some of the air flow problems to the longest runs(farthest rooms).


Today you are trying to move more air than needed thru the duct system.Reducing that amount will allow more air ,relative to air delivered to other rooms,to get to the farthest rooms.


That's what the equation posted is intended to show.


You need to call around and find a Pro in your area that understands this .


After 15 pages ,YES ,you bought the wrong furnace!!LOL!!!

[jeffw_00]

"Today you are trying to move more air than needed thru the duct system.Reducing that amount will allow more air ,relative to air delivered to other rooms,to get to the farthest rooms."

Yes I need a pro who understand this, but I need to understand it too. If I reduce overall airflow, -more- air will get to the furthest rooms? With more noise too?

can you explain a bit better? I won't know if my contractor understand it unless I do.

thanks!
/j

[hydronicsman]

look at it this way. Your ductwork is just so big. if you try to cram more air than it can handle down it, the air will go out the nearest and easiest paths. Lowering CFMs will let air travel to take offs farther down the line. I know it sounds weird, but think like lazy air.

Same thing with steam systems. Higher pressure steam is slower.

[dan sw fl]

Originally posted by hydronicsman
... I know it sounds weird, but .

Same thing with steam systems. Higher pressure steam is slower.

.. Slower than A Jet.

[dash]

Originally posted by jeffw_00
"Today you are trying to move more air than needed thru the duct system.Reducing that amount will allow more air ,relative to air delivered to other rooms,to get to the farthest rooms."

Yes I need a pro who understand this, but I need to understand it too. If I reduce overall airflow, -more- air will get to the furthest rooms? With more noise too?

can you explain a bit better? I won't know if my contractor understand it unless I do.

thanks!
/j

How's this,not the correct terms ,but hopefully easier to understand.

The fan only has X amount of energy to move the air.

The longest runs ,will have the least amount of energy available to move air ,as it is used up before the air gets there.

If we use a fan with the same amount of energy available,to move less air,it won't be used up by the time it gets to the longest runs because it had less air ,overall ,to move.


Moving less air thru the same ducts ,the air will move slower and make less noise ,as well.


Today in your system too much air gets to the closer runs and cycles the unit off.A smaller unit will run longer ,hopefully getting enough air to all rooms ,so when it cycles off they are all the same temp..Running longer but using about the same amount of gas.

A smaller system will get "more" air to the longest runs ,but if the are groosly undersized,there will still be a temperaature difference although not as much as you have now.That's why you need a Pro to calculate this and see if duct changes are required.

[jeffw_00]

seems a bit counter-intuitive (I would think that the temp loss across the length of the duct would go up as you slowed the air flow, not down), but ok - thanks!

[jeffnette]

I have been reading this 15 page post and have come to the conclusion that this guy just does'nt get it. From the beginning everyone has told him the problem but he always seems to want to question it. Why come to this forum with this problem, and have numerous professionals tell you how to fix it, and you don't seem to want to? Maybe you like the turmoil of it all!
Just my opinion

[jeffw_00]

Jeffnette - with all due respect, clearly you're not reading the post. I do want to fix it. However, I'm not a magician. I can't instantly make myself the highest priority of my contractor, I can't instantly rip my house to the studs and "just" put in a complete new duct system. (I get how that is easy do to in some house designs, mine isn't one of them, as I've described). And, I'm in a better position to handle my contractor the more I understand. So what have I been doing? Asking questions to understand -why- people think I need to do as I do, getting ideas for workable solutions, and (off-line) making progress with my contractor. Wednesday was a big win when I proved to the tech there was a big problem. I have a call into them now and if I don't get a call back I will talk to the owner on Monday.

I suppose a lot of people just reply with "Oh, ok, I'll call the contractor and tell him to replace the furnace and duct system for free, he'll do it", but do you really think tht happens 8-}. How often have you done this for a customer, just because he asked?

Thanks to everyone for their help, I'm learning a lot, and getting to a superior result.

/j

[dash]

Originally posted by jeffw_00
seems a bit counter-intuitive (I would think that the temp loss across the length of the duct would go up as you slowed the air flow, not down), but ok - thanks!

Yes it may, but unless they are uninsulated and exposed to a large temerature differential,it won't be much.


One more try:

Lets say the current unit delivers 1600 cfms ,now due the resistance ,1400 cfms(87.5%) goes to the closer runs and 400 cfms(12.5%) to the longest runs.

Replace it with a 1200 cfm unit that has the correct btus for the home.

Now with only trying to deliver 1200 cfms ,25% less ,there is less resistance to the lower cfms in the same duct system.

So it may now deliver 850 cfms(71%) to the closer runs and 350 cfms(29%) to the longer runs.

Altough less cfms to the longer runs it is a much larger percentage of the total.Smaller furnace ,will run longer using less fuel per minute ,air is distributed more evenly,home is comfy,all live happily after!!


Yes you have some temperature loss in the ducts,you think that is the sole cause of the problem,because you "understand" cooler air less heat.

We are trying to tell you there's another problem ,I tyhink you are to fixated on the one you understand, to learn about the the one we are trying to explain.

[Edited by dash on 02-24-2006 at 01:15 PM]

[jeffw_00]

Originally posted by dash
[
So it may now deliver 850 cfms(71%) to the closer runs and 350 cfms(29%) to the longer runs.
[/B]

OK - I get it. That's VERY interesting. It sounds like my plan of action should be
1) let them do the CFM readings, prove that, along with the temp being too high, the furnace is putting out way less CFM then it should. (or perhaps convince them on the basis of the plenum temp)
2) replace with smaller furnace, based on heat load (the next 2 choices are 94K and 75K (current is 112K), I'm guessing the 94K will be right)

3) THEN, if the far rooms are too cold, think about duct work.

I like it. I'll be talking to them Monday.

Thanks
/j

[tinknocker service tech]

i would also recomend insulating as much duct as you can this will keep the air hot longer

[dan sw fl]

Originally posted by jeffw_00
... It sounds like my plan of action should be
2) replace with smaller furnace, 75K (current is 112K), I'm guessing the 94K will be right)

I'll be talking to them Monday. [/B]

16 pages & 24 days later ...
+ Still Guessing

L.O.L.

[atphvac]

This is the "A Chorus Line" of threads. LOL

[jeffw_00]

Hi guys - I'm glad this is entertaining, but if you have a faster way to solve it, please let me know - or maybe you give your best service to your most impatient, demanding customers, while shafting the patient ones who try to work with you? (Now I'M LOL 8-})

Oh - and tink - the ducts are already insulated in the one place they are exposed, but they're almost entirely embedded in the walls and floor. In fact, I believe some of them touch my water pipes because after the heat runs for a while, we initially get hot water out of the cold taps (sigh).

[phinncraft]

go and bite the bullett install a 2 stage type furnace and it will solve the problem.they provide a more even heat

[jeffw_00]

thanks, but there's some debate here as to whether 2-stage will work. Specifically:
1) if the high speed is still low enough to work with my ducts (probably no more than 1200 cfm), then will the low speed be useful?
2) Will a variable-speed fan work ok with my duct system?
/j

[t527ed]

not familiar with bryant furnace models. if multi position furnace why not use it as blower for a/c and stick it up in attic. you may be able to play around with your current WAY undersized ducts, but it will never be right or efficient.

[jeffw_00]

I already have a new A/C system (Evolution), installed at the same time as the furnace...

[tinknocker service tech]

Originally posted by jeffw_00
Hi guys - I'm glad this is entertaining, but if you have a faster way to solve it, please let me know - or maybe you give your best service to your most impatient, demanding customers, while shafting the patient ones who try to work with you? (Now I'M LOL 8-})

Oh - and tink - the ducts are already insulated in the one place they are exposed, but they're almost entirely embedded in the walls and floor. In fact, I believe some of them touch my water pipes because after the heat runs for a while, we initially get hot water out of the cold taps (sigh).

jeff
i dont think this is a joke. i think it is a sin.
your patience is comending and also your grasp of the cercomstance.
now here is what i think. the duct system may be a problem to some extent but the main problem is the size of the furnace. no i wouldnt be putting off a patient coustomer to take care of the pain in the ass one. i would be addressing your concern just the same if not more. the company made a misstake witch we all have done at some time.
how the mistake is handled is what is important.
doesnt matter what you are saying about the coldest days if the ducts cant handle a furnace the coldest doesnt matter
size the unit for the house and install the proper size unit
if the ducts cant handle what you want to put in then make whatever ajustment needs to be made to acomadate the new unit.
to just guess and then keep putting the coustomer off hoping he goes away isnt funny
hit the tab on the top of the page and see just what size you you need for your house and then stop all the guess work. now you will have something to go with when you talk to the contractor about the unit.
if you find the unit is the right size then you adress the ducts. if it is not and you need smaller the adress the unit
either way stop guessing and do a load on your house

[jeffw_00]

tink - we're on the same page - The contractor just found out last Wednesday (when he did measurements) that there's a real problem. My expectation is that they will want to do more measurements (cfm), the heat load calc, and probably come and look a couple of more times before they swap out the furnace. I'm planning on calling them Mon. or Tues. to see if I can get things stepped up, now that the initial visit proved there was a big problem. I agree that the first step is a furnace swap, with duct work as a step-2 if necessary. If I don't hear by Tuesday I plan to call and talk to the owner.

Thanks
/j

PS - I started to play with the HVACCalc, but it seems like there's a lot of data that has to be entered (3 dimensions for each wall = 12 for each room, plus window data), and I have 15 rooms, so I'm inclined, for time and money, to see if the contractor does a plausible job, and only invest the day myself if he doesn't.

[jeffw_00]

Ok - I think I'm having a problem getting my A/C company's attention.

They called and said they thought that since the plenum temp was well below the cutoff switch and their heat calc showed that the furnace size was right, there wasn't a problem.

I re-iterated my points (and followed up with a fax) -
1) plenum temp is above spec
2) static pressure is high
3) furnace may be sized for house (or not) but clearly is oversized for duct system (which doesn't serve all the rooms).
4) furnace is out of spec and thus warranty void.

He said he would talk to people and get back to me, what's concerning me now is that this may not be resolved before the heating season is over. I showed good faith with my initial patience, but now I need to step it up a notch.

What leverage do I have to get their attention? They're getting busy now, and I think that people paying them money are getting priority. Do I call Bryant and complain?

all suggestions welcome. Calling them up and yelling won't help. Polite threats that have substance might.

Thanks
/j

[tommy graham]

Knew you were being to nice...... Was the job inspected?? If not call the county and tell them you are, if still no response tell them you are gonna call the state. Bet somebody gets their ass in gear then. Wondered why I had got no e's on this post, you know its gonna get nasty now




“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[Advanced Response]

Jeff,

Did they provide you with a manual J report?
I figured they would say that the furnace was the correct size,, but did they actually do a correct load calculation after taking room measurements, window sizes, insulation in walls and ceiling, etc,etc..? This is why I highly reccommend to have a load calculation done by yourself or hire a company to do it properly.. HVAC Calc is very simple that even a average homeowner that can operate a tape measure can operate,, Don will guide you thru any problems you have with the inputs or you can ask us here..

I can not tell you how to proceed with your current contractor as he sounds like a hack the way he has treated you and handled the situation... Time to get a real pro hvac contractor out to review your situation and provide viable solutions to your problem..

I don't know if there are any hvac contractors from this website on this forum but you may want to start another post requesting help in your area from a real pro..

Goodluck
J

[dash]

Originally posted by Advanced Response
Jeff,

Did they provide you with a manual J report?
I figured they would say that the furnace was the correct size,, but did they actually do a correct load calculation after taking room measurements, window sizes, insulation in walls and ceiling, etc,etc..? This is why I highly reccommend to have a load calculation done by yourself or hire a company to do it properly.. HVAC Calc is very simple that even a average homeowner that can operate a tape measure can operate,, Don will guide you thru any problems you have with the inputs or you can ask us here..

I can not tell you how to proceed with your current contractor as he sounds like a hack the way he has treated you and handled the situation... Time to get a real pro hvac contractor out to review your situation and provide viable solutions to your problem..

I don't know if there are any hvac contractors from this website on this forum but you may want to start another post requesting help in your area from a real pro..

Goodluck
J


The above and call Bryant to the rescue!!




Seriously call them.

[jeffw_00]

Thanks for the comments - in reply....

I gave them a thorough house plan (I happened to have one) and I marked all the windows by model number and attached the appropriate couple of pages from the Andersen catalog. I actually didn't have the windows marked originally but the guy who came out pointed out the omission. I've received nothing from them in writing.

I believe that someone there did a heat load calculation from my specs. I can't attest to how thorough it was, or to whether they 'rounded up' to try to appease me. I have asked to see it, as maybe there's somethig obviously wrong, or if not, it will make it easier for me to do my own.

This is a local company with at least 1/2 dozen trucks who have been in business for a lot of years. I checked them out on BBB first, and went with them because we had used them successfully for some plumbing repair and A/C maintenance, and they seemed mid-priced and interested in my business. They recommended the same size furnace that everyone else did.

F Y I - New England seems to have a chronic shortage of good tradesmen so the good ones are always quite busy, and the run-around I'm getting is not unknown to me. Of the 6 or 8 companies (all the big ones, and a couple of smaller ones) that came to quote A/C or heat for me in the last 6 months not -one- of them had any interest in taking house measurements or putting the level of pre-sales effort in that you guys say I should expect. They don't have to here. They get the business without it.

I don't -know- if my guy is -bad- or not yet. My problem is I haven't come up on their radar. To do so I need to either nag them, or some sort of leverage. Sounds like it's time to mention that since they're so busy, I will make things easier by calling Bryant, telling them all the spec issues, and let Bryant tell me if I have a problem or not. It sounds like, if they're any good, they will try to keep me from doing that.... 8-}
.

Thanks
/j




[Edited by jeffw_00 on 03-04-2006 at 12:55 AM]

[precision hvac]

This whole story smells like a rat. You get multiple bids & go with this guy. Why? Cheap? Did the others recommend a higher priced high static furnace install & you didn't want to spend the cash? Did the others all recommend new ducts & you being the engineer- are smarter than them & think it's an un-necessary expense?

Be honest. Did they recommend ducts as part of the job & because of the price, you went cheap? Sure sounds like it to me.

No such thing as an impossible installation. No such thing as "I can't replace ducts because of space constraints".
If round won't work- that's what flat stock is for. Fabricate!

You have a several choices.
Live with your current system & count the days until failure- while your contractor is out spending your money. Install the proper high static furnace designed for such an installation (I'd bet that's what your neighbor has & I'm still waiting on a brand your neighbor has) & send the other one back. Get load calcs!!!!
Install a new system properly sized for your home including properly sized ducts.

If you indicate you are going cheap & not replacing the ducts- you just narrowed your choice to a high static furnace.

So, in summary- we still have no ESP, correct temp rise, have no clue what furnace your neighbor installed & are having no issues with, you still insist on playing HVAC tech, have no intentions of replacing ducts, are still sweet talking the installer, are unwilling to pay more for a quality installation.

So far- we've heard 1 side of this story. I'd bet money there's a completely different side of this story we haven't heard & I'd love to hear it.

So- I'm calling your bluff. As a former industry expert for the CSLB- I have many contacts.
If you are truthful- send me a copy of the HVAC contract for review & all the other bids. Send me the name of the installing contractor- name of principle contact, contractor's license number & I will contact him for his side of this story. Send me the number for city hall, name of chief mechanical inspector, permit number & who inspected the installation. I need all pertinant information.

If we find out you were told to install new ducts & opted to go cheap- you've wasted our valuable time & expertise.
Lets get to the bottom of this crap right now & stop wasting everyone elses time.

So, are you game?

[jeffw_00]

I'm always game, and I have nothing to hide. So here's the truth…

I went with this guy because of the 2 people who actually did Bryant/carrier they seemed the most interested and reputable. I had used them for routine work and was happy with their results (and actually, the installation went very well, they did a furnace, A/C and hot water heater in 3 days, on schedule with no issues).

Of the 3-4 quotes I got on the furnace , all recommended about the same furnace, about the same BTU. All told me that I shouldn't expect a perfectly balanced system because of the ducts, but that they could see how duct replacement was out of the question, so no, no one recommended duct work. (I honestly suspect you wouldn't have either, have you seen the pic I posted - on the other hand, I did post that I found a way to reduce the lengths of the ducts by stretching the main, although I don't think that will affect the static pressure because it won't increase the number or size of registers).

Everyone did really give me about the same story. Honestly, and -no one- mentioned a different type of furnace. (Well, they all mentioned a 2-speed but said that the lower speed wouldn't get the air out to the far end of the system).

I resent the implication that I'm somehow a cheapskate - if I was, would I have had an Evolution system put in for A/C at the same time? I thought I was putting in the best thing I could.

Clearly I don't want to live with the current system, that's why I'm here.

I'm not about to take a poll of my neighbors. However, we do get together for block parties a couple of times a year, and though a number of them are full of suggestions "if you do X, make sure you do Y", none that have had their furnaces replaced have ever said "you have to make sure you do X", or had any horror stories. Yes that's soft data, but it's what I've got.

We have no ESP measurement. I'm pushing for it. We DO have a temp. rise measurement, and it's enough of a smoking gun for me to apply some pressure, I hope.

At this point, I'm not sure why my first choice should be duct replacement as opposed to a smaller furnace. Yes, I could add ducts and registers to 'drain' the excess air, but why not just reduce the amout of air generated to better match the duct system?

I think the basic problem is no one realized that the furnace needed to be matched to the duct system rather than to the house size.

There really isn't another 'side' to the story here, yet, unfortunately, because I've had minimal contact with my installer. Problem is getting them to realize there is a real problem here. End of Feburary was a wake-up call for me because I want this resolved before it's warm. Armed with the threat to call Bryant I plan to start nagging them on Monday.

I appreciate your offer to help, but I don't think you're clear on the situation, and I'm always a little concerned about sending personal information to someone I met on the internet 8-}. Though, if I don't have any luck in the next few days lighting a fire, and you think your calls will help, I'll drop you a private Email.

And I apologize if I'm wasting everyone's time. Please understand how little credibility I'd have with my contractor (as I would have with you) if I called up saying "my furnace is wrong, I don't really understand why, but everyone on the internet is telling me you guys have to do something". Please also understand, and I may be wrong about this, that I don't feel screaming at my contractor on day 1 is the way to get a good response (does that really work with you?)

Yes I'm an engineer, which means:
1) I'm methodical
2) I understand you couldn't become an expert in my speciality easily, and nor could I become one in yours.

but aren't those 'good' things? 8-}

Again, thanks for all your help
/j

[precision hvac]

And not 1 of the bids was for a high static furnace?
No way would I have installed that system on those ducts.


You keep saying your neighbors installed furnaces on those same ducts & have had no problems. So- you have had conversation w/ neighbors. But now you can't be bothered enough to pick up the phone & ask what they had installed? I'd sure be curious.

I predict in a year or 2- you will be paying someone else to tear this mess out & install something else.

Only reason this contractor isn't calling you back is because he told you up front & probably right on your contract it would not work w/ those ducts.
Too busy to call or come out? I don't buy it.

Prove me wrong. Send me the contract & the installers number.


Again- did they pull a permit?

[Edited by precision hvac on 03-04-2006 at 03:13 PM]

[Jultzya]

It's not for anyone to prove their side of the story here. This is not a court trial.

As far as wasting time, you can choose to reply or not reply.

As with anyone, if you don't feel that the poster is being honest and trustworthy, back off and ignore the thread.

Otherwise, please continue to keep it civil.

Thanks

[jacob perkins]

Originally posted by jeffw_00
. To do so I need to either nag them, or some sort of leverage. /j



Probably best to just be nice and work with 'em. Threats and leverage only work with certain types of people,and fortunately those people are few.

You have the performance data recorded, so the changes can be made during the off season if need be.

good luck

darnit,I wanted to be on the 18th hole here.

[Edited by jacob perkins on 03-04-2006 at 03:58 PM]

[jeffw_00]

Thanks Jultzya - but I have nothing to hide....

Jacob - my concern about off-season work is what if we get to to next December and an -5Deg night and the smaller furnace isn't cutting it. Don't I have reduced leverage a year out? (or, better put - isn't it better to get it resolved sooner rather than later 8-})

precision HVAC:

Originally posted by precision hvac [/i]
And not 1 of the bids was for a high static furnace?
No way would I have installed that system on those ducts.


Really. No. the most common comment was a concern that I may have to run the fan on A/C speeds.




You keep saying your neighbors installed furnaces on those same ducts & have had no problems. So- you have had conversation w/ neighbors. But now you can't be bothered enough to pick up the phone & ask what they had installed? I'd sure be curious.
[/B]

I tried that with one or two neighbors, and it was tough to get a brand out of them, much less a model number. MAny of them did it over a decade ago (or more, the neighborhood is 45 years old) so maybe there was less of an issue with theirs.



I predict in a year or 2- you will be paying someone else to tear this mess out & install something else.
[/B]

Yes, Hello. Duh! I know that. You're preaching to the choir. That's why I'm trying to get it addressed.



Only reason this contractor isn't calling you back is because he told you up front & probably right on your contract it would not work w/ those ducts.
Too busy to call or come out? I don't buy it.

Prove me wrong. Send me the contract & the installers number. [/B]

Sorry you don't buy it. It's absolutely true. Still I want to show that I'm genuine, and if I have to upload the contract to provide to you folk, so be it. However, I did remove the pricing (as per forum rules), and my and the contractor's name (for privacy, this is still the Internet). If you feel it's otherwise altered, god bless you, but it's not.

Contract is here:

http://img221.imageshack.us/img221/7752/fax06hp.jpg
http://img221.imageshack.us/img221/4153/fax13sy.jpg

Best Regards and Thanks
/j

[re2ell]

Originally posted by jeffw_00
For the curious - here's where my main duct terminates and about 70% of the individual runs originate (the other 30% are at random points on the main closer to the furnace). From the point of view of the picture the furnace is about 10' behind you.

http://img106.imageshack.us/img106/3410/ducts9gs.jpg

Thanks for posting the pic! I wanted so much to respond to this post when I first read it, thought I'd better let it simmer for awhile (in my head) before I said anything at all. You have exactly what I drew on paper from your description!

Just a short note that might help. I would venture to say that your TESP (total external static pressure) is somewhere in the neighborhood of 0.8 to 1.0 inches water gauge. The blower in your furnace is more than likely to deliver its rated airflow @ 0.5 inches water gauge.

Possible solution: Have your contractor select a blower that will delivered the required airflow @ the static pressure he measures. You might end up with a blower that has a 1 to 1 1/2 h.p., motor vs the 1/3 h.p. motor you currently have. As far as air noise, have your contractor install dampers in the affected branches.

And for the issue of the longest branches delivering cool air, have your contractor insulate all the main duct and all the branch pipes.

Its just a thought....I think you could live with that without a complete overhaul.

One last observation, I noted from the picture that many of your branch runs are coming from the end of the duct. By good design practices, this procedure is not acceptable. The ends of ducts should be capped off, the branches are to be taken from the top, sides, or bottom of the main duct.

[Edited by re2ell on 03-04-2006 at 04:58 PM]

[jeffw_00]

Thanks for the Post re2ell - One thing....


You said: Possible solution: Have your contractor select a blower that will delivered the required airflow @ the static pressure he measures. You might end up with a blower that has a 1 to 1 1/2 h.p., motor vs the 1/3 h.p. motor you currently have. As far as air noise, have your contractor install dampers in the affected branches.

ME: doesn't the blower have to be matched to the heating element? Also, won't this increase CFM and noise?

(also, the branches are insulated where they are accessible, and by raising the house temp a degree or two I have enough warmth at the far end.)

Thanks - I appreciate the constructive response 8-} Looking forward to learning more...
/j

[tinknocker service tech]

jeff
altho i know this would cost a lot but
has any one mentioned putting a furnace in the attic with a coil in place of the airhandler and a much smaller one in the cellar. this way you could get the extra you need on the very cold days and to the rooms that need the extra.
inother words two units and a realy quite system with out changing any ductwork.

[jeffw_00]

Thanks Tink. It's a solution, but maybe not the most cost-effective one. A problem with heat in the attic is that the A/C ducts only have 1 feed to the lower two floors (and all the registers are in the ceilings - living room has a cathedral ceiling and feed is 13' up!)

Someone said that if I have a static pressure problem, I'm already getting CFM closer to what I would get with a lower furnace. So if I got a smaller furnace with less blower CFM, proportionally more air would go to the further ducts and take more heat with it. I'm still leaning towards starting with a smaller furnace and then if there's a problem getting the heat to the far ducts, extend the main.
/j

[re2ell]

Originally posted by jeffw_00
Thanks for the Post re2ell - One thing....


You said: Possible solution: Have your contractor select a blower that will delivered the required airflow @ the static pressure he measures. You might end up with a blower that has a 1 to 1 1/2 h.p., motor vs the 1/3 h.p. motor you currently have. As far as air noise, have your contractor install dampers in the affected branches.

ME: doesn't the blower have to be matched to the heating element? Also, won't this increase CFM and noise?

(also, the branches are insulated where they are accessible, and by raising the house temp a degree or two I have enough warmth at the far end.)

Thanks - I appreciate the constructive response 8-} Looking forward to learning more...
/j


I apologize for not making myself clear. You are correct in your statement 'doesn't the blower have to be matched to the heating element?'.

I am not advocating increasing nor decreasing cfm of the blower. Let's keep that where it is!

Inform me if I'm in the ballpark -- the branch runs coming from the end of the main duct are putting out more air than the branch runs coming off the sides.

If it is feasible, have your contractor blank off the end(s) of the main duct, and have your branches come off the bottom. Beings that air has enertia energy as it moves down the duct, it will seek out the path of least resistance, this being those little devils at the end, with no energy left to cause the air to turn into the branches coming off the side. Your entire system will show you a new attitude, you might be surprised what difference it makes.

[jeffw_00]

Originally posted by re2ell
Inform me if I'm in the ballpark -- the branch runs coming from the end of the main duct are putting out more air than the branch runs coming off the sides.

If it is feasible, have your contractor blank off the end(s) of the main duct, and have your branches come off the bottom. Beings that air has enertia energy as it moves down the duct, it will seek out the path of least resistance, this being those little devils at the end, with no energy left to cause the air to turn into the branches coming off the side. Your entire system will show you a new attitude, you might be surprised what difference it makes.
[/B]

The ducts close to the main are by and large short runs, and if left wide open they put out a tremendous amount of air. With the old system, however, the volume from almost any duct was a about the same - maybe that's why the longest ones are on the end of the main, the inertia compensates for the length (up to 40') of the run.

yours is an interesting idea - it will cut the cfm and noise to those ducts, but won't it increase the static pressure and plenum temp even more?
/j

[re2ell]

Any changes in static pressure would be minimal, the effect it would do is to vent the energies already present and equal out the pressures in the entire system. The way I see it, the only thing that would change the static pressure is change the size of the duct, and/or increase the cfm, I wouldn't suggest either of those.

[dash]

Smaller furnace less cfms,less cfms in the same duct system will reuce the static,and deliver more air to the farthest runs than you currently get.

This may solve the problem ,unless the farthest runs are undersized a lot more than the closer ones.

PDx=PD1 X(cfmx/cfm1)squared

PDx=.3 X(1200/1600) squared

PDx=.3 X(.5625)


.16875 is the new PD

So reducing the cfms on the example ,reduced the PD or static by almost half.The fan now has the static to move the air farther in greater proportional quantity ,to the farthest runs.

[re2ell]

a couple thoughts to ponder........perhaps the old furnace had sufficient enough dirt build up in the vanes of the blower wheel to keep the volume of air delivered low enough that air noise wasn't noticed.

secondly, by having dampers installed in the problem supply branches as your primary means of controlling airflow, not relying on register dampers, those are designed to 'fine tune' airflow, not good to throttle with.

I've included this link since you show a great interest in the subject matter of fans and fan laws. Hope this helps in your understanding.

http://edis.ifas.ufl.edu/pdffiles/AE/AE02000.pdf

note: Don't be misled by the title of Greenhouse, all fan laws are presented

[jeffw_00]

there are no dampers at the registers, they are old style funny looking things with no way to add a damper.

I'll get to that website - thanks.

also - got the heat-load calc today - will post later
/j

[re2ell]

Good for you!

Air volume dampers are to be located in the round pipes not too far from the main duct.

[Edited by re2ell on 03-06-2006 at 05:23 PM]

[jeffw_00]

yes - that's where they are located. They are in fact the 'only' control as there is no damper possible on most of the registers

[jeffw_00]

I've posted the heat load calculations at

http://img375.imageshack.us/img375/5915/heatload19gp.jpg
http://img375.imageshack.us/img375/9693/heatload23mi.jpg

Apparently they gave the info to their supply house to do the work. What I notice right off is a large BTU loss allocated to the basement, and 'storage room' (former garage). There are no enabled outlets in the basement. It's mostly underground, and what radiates from the furnace and the main duct seems to be sufficient to keep the room at house temperature. The storage room, if heated properly, would probably present a large BTU loss, however, the duct system wasn't designed to supply this room. I have one (3.5") run going to it, but this room typically 5 -10 Degrees colder than the rest of the house, which is a different problem to solve. We've discussed extending the duct system to that room, but right now it's not really warmed.

There a couple of other minor measurement mistakes, but what I also notice is that they don't seem to account for underground basement walls, or interior vs. exterior walls, and relative amounts of insulation. (Nor do I see a place for these). Yes, maybe I need to clear a day to do it myself, it's this pesky (7-) day job.... (although it could be a wash, much of my ceilings are only adaquately insulated..., only 6" of room to put insulation).

Also - the sq. ft numbers for glass are somewhat random, the total seems in the right ballpark.


Still, I think my bottom line is the same: the furnace is oversized for the duct system, and possibly for the house as well I made my plea for attention this morning (that's how I got the heat load report), and am supposed to get a call from the owner tomorrow. We shall see.

/j


[Edited by jeffw_00 on 03-06-2006 at 09:01 PM]

[re2ell]

here is another link shedding light on the importance of sizing, for your reading enjoyment

http://www.nrel.gov/docs/fy02osti/31318.pdf

[tony82164]

Originally posted by jeffw_00
I have 3000 sq ft house in New England. My previous gas FHA furnace was a Coleman "high velocity" furnace. This drove a main duct that is about 1' x 3' x 12'. Off of this main are about 20 3.5" runs varying in length from 3' to 30', with most being in the 10-20' range.

I replaced it last week with a single-stage Bryant 350AAV with 4-speed fan. We have the fan cranked down to the lowest setting, and it still moves more air than my old furnace (and thus is noisier). With the current outside temps of 30-40DegF, the furnace doesn't cycle for more than a couple of minutes every 15min or so because it appears to be much more efficient at heating the house. I recognize that performance may be different when we get our few weeks of 0DegF weather, but on the other hand a lot of our winters are just like this.

The new furnace has the same 112K Output BTU as the old furnace. I recognize that the effective output BTU of my old furnace was lower, but we added about 400 sq ft of heatable space to the house since we bought it and there was some feeling that the old furnace was on the edge or slightly less than we wanted (When it was really cold out, if we had shut the heat off for a while, it could take hours for the furnace to bring the house back to temp).

All 3 contractors that quoted me recommended a single-stage furnace because they said that the lower fan speeds of a 2-stage furnace would be insufficient to drive air through the system. I raised this point a couple of times with the company that did the work (Who I'm otherwise VERY happy with), and they felt strongly that a 2-speed would be wasting my money.

However, I'm having buyers remorse. It seems like it would be more efficient, quieter, and perhaps more comfortable to have less BTU and slower fan taking longer to heat the house. (also, that would permit more runtime on my Humidifier which would also be a good thing).

I'm also concerned about this: To get more even heating, a little more hysteresis, and reduce the noise, I re-balanced the ducts, with the new effect of have them closed down a little more than before. Is it bad for the system fan to have to push the air so hard? (I think with all the ducts open there would still be some back-pressure, it's really a powerful fan).

I haven't talked to the contractor yet, because I want to try switching out the 18yr old Honeywell clock stat for a new (White-Rodgers) electronic one. I noticed that the system performance seems independent of the anticipator setting so I'm wondering if a broken stat is part of my problem. (Although the temp at the stat does stay fairly consistent).

Still, I'm posting because I have two questions:

1) For those of you who have experience with two-stage furnaces, do you think one would be good for me? What I'd like is a fan speed that pushed about 80% as much air as the lowest setting on this one. If the extra fan speeds on a 2-stage are like 50% slower, or only run in certain conditions, then it won't do me any good.

I get that a smaller furnace might be an option, but I don't want to go there until I've lived though some 0DegF nights with this one.

2) If we all agree I have the wrong furnace, what can I do about it? I don't think it's fair (or possible? ) to ask the contractor to 'eat' the furnace. Can he re-sell it? Does Bryant have a 'satisfaction guarantee'?

Thanks very much
/j I would try that new T-stat first if that does not work you can install a duct heating element or in the furnace there may be a place to install one, 400 Sq.feet to add on requires more heat. Tony82164

[jeffw_00]

Ok - talked to the owner this morning. Long story short...

1) He sounded like some of the more opinionated people here in his distaste for my duct system. Said that I'd never have a great system with the ducts I have (and yes, they told me that up front as well). I told him I was ok with that, and I understood, and all I want is a furnace that is somewhat matched to the duct system (this one just seems, well , way too big).

2) He agreed that if the system is running in such a way that it's damaging the furnace that something needs to be done. He suggested that it's possible the tech didn't measure the temp rise from the right place - wants to talk to Bryant and then come out and measure it himself. He said he doesn't think he has any good way to measure the pressure because his CFM machine is designed for normal duct sizes (6", 8", etc). However, he seemed amenable to the idea that, since I've observed this system is pushing so much more air than the old one, there's probably a problem. In fact, he suggested that the original system probably pushed more air, but it degraded with time, possibly due to the excessive pressure.

For a possible solution - he said that a lot of these Bryant furnaces are the same inside except for the heat element and blower, and so he's more inclined to swap these components rather than replace the whole unit. I can see how this is a lot less labor cost for him. But don't know if its ok for me.

He's coming by early next week. Generally, I think I have his attention until such time that he convinces himself that the furnace is (or isn't) at risk for a short life. He's being very amenable about it for now.

So, I have two questions to this forum:

1) I don't know how to respond to his not being able to measure the static pressure - what should I expect him to be able to do? I do have non-standard ducts and very funky registers.

2) How should i feel about him doing component swapping rather than swapping the entire unit?

T H A N K S!
/j

[Edited by jeffw_00 on 03-08-2006 at 09:05 AM]

[re2ell]

Jeff, would you please post your complete model and serial numbers of your furnace? with that info, i can look up all the specifications of your equipment, e.g. blower data

or I welcome you to email me with the info, my addy is in my profile.

[jeffw_00]

http://www.xpedio.carrier.com/idc/groups/public/documents/techlit/pds350a.40.1reva.pdf
see page 5, mine is the 060120

[Advanced Response]

Jeff,

This company sounds like they don't know how to do anything right..

If he doesn't know how to measure static pressure or has the proper tools then he should not be in the business..

To check static pressure you can use on of these:
1.) A 0-1 inch magnahelic,,, $25-75 for tool
2.) A digital Manometer,,, $150-500 for tool

Knowing how to use it and what it means Priceless... Your company doesn't know how to do anything..

Also, they can use a balometer or a tranverse of the duct to find the cfm going to each room,, which would tell what rooms are the most out of shape..

I would call bryant and talk to them about the incompetance of the installer and see if they have a field rep that can properly check your system..Or hire, an outside hvac contractor that knows how to do things properly..

Do not let your contractor change parts to the furnace with another smaller furnace.. If your furnace is the wrong size,, they should replace the furnace, not change parts..

At this point, you would be better off finding a new company and having it redone properly by the new company and explain this to you current contractor.. A lawyer may be needed..

I am sorry,, but you have a hack... You need a real pro.. As you can see, they don't have the tools or knowledge to properly remedy your situation...

Goodluck
J

You should contract a contractor to properly do a load calc for you... I can make a bet their calc is hogwash.. As much of what they have told you is hogwash..

[jeffw_00]

Thanks AR - you have given me the tools to assess whether, when they visit, they are indeed a hack. If I call Bryant now I suspect they will tell me to see what happens at the visit.

Two questions though:

What's a "transverse of the duct"?

Why is the the part-swapping a bad idea? I could imagine that all the furnaces of the same model are built on the same chassis with only the blower, heat-exchanger, and perhaps a circuit board (or even a ROM) different between units. I'm not pushing back on you, but if I want to push back on him, or Bryant, "Someone on the Internet told me" isn't a great response.

Thanks
/j

[Advanced Response]

Reasons not to replace parts to modify unit:

1.) We as service providers use model/product numbers to get the right part for your unit.. If you use a differant heat exchanger and blower motor, then your model/product number will not reflect the correct parts in the unit..

2.) Also, do you want to trust a hvac contractor that does not know how to properly check something as simple as static pressure, to redesign your unit to make it have a smaller output/size..

3.) I don't believe a manufacturer will allow modification of a system.... They require the parts to be the same parts that are required by the model # of the unit not a Model # of a smaller unit.. Just check with Jrbenny or Robo...

4.) Do you want to have to deal with this hack company to do any warranty work as,, they will have to warranty any parts because they modified a factory unit..

You asked what a "Tranverse of a duct" is.. It is just another way to properly check cfm for a particullar heat run pipe.. I prefer to use a Balometer flowhood(this device looks like a canvas hood with tubes/holes to check cfm from registar)....
To use a Balometer, They would put this flowhood over the wall/floor registar and make sure all the airflow is going thru the hood and it will read the amount of cfm coming from that vent.. Each room requires a certain amount of airflow to properly heat and cool,, this will determine where the airflow is going and how much..

I can already guess your hvac contractor is going to come out and state he talked to bryant and rechecked everything and it is fine,, just as he supplied a possible hogwash load calc to say the unit is properly sized... He has not impressed me in your posts that he is concerned about the longevity of your unit,, just that it will not cost him any money..

Static Pressure is a simple check,,, just as simple as a temp rise,, Amp check,, voltage check, gas pressure check,, etc.. Several simple checks,, wonder how many they don't know how to check or have the proper tools.... hack/hack/hack/hack/hack/hack/hack,,, excuse me hack/hack,, I have not coughed that hard in a while...

Goodluck,, you sound like your need it..
J

[jeffw_00]

From what you describe, he sounds like he has a balometer but doesn't think it will work on my small ducts and weird registers. He says his has to be adjusted for the duct size.
AR - Have you looked at the heat-load calc? (I posted it), it was done by his supplier (FW WEBB is a big supply company out here), the sizes look right, except he included rooms that don't have airflow (or much airflow) to them. It's possible that with a proper duct system this furnace might be about the right size for this house.

I agree with you in that I was also very suspicious of the parts swap. But remember, this was my first call with him, he has to go check things, talk to bryant, etc, and he is coming out himself early next week. If my post was the result of the -visit- I'd agree with your characterizations.

btw - When I mentioned that it was better to fix it now because he could re-sell the old furnace that seemed to strike a chord.

How many contractors-owners make a quick decision to replace a furnace that their people (who are doing a bit of CYA) say is ok? He could have told me that his estimator said everything was ok, Instead he is making inquiries and planning a visit - should I expect any more?

/thanks
/j


[Edited by jeffw_00 on 03-08-2006 at 03:13 PM]

[Advanced Response]

Jeff,

I have never seen a load calculation layed out that way and it is also hard to read.. It doesn't look like it took in which way a wall or window faced(north/s/e/w).. I also did not see where it stated the outdoor design temp or indoor design temp..

It could be a valid load calc,, but I have my doubts.. I know many contractors both small and big but if they are in the business to do it right, they own their own load calculation software..

I hope I am wrong about your contractor but the impression I have of them is not good for you..

J

[beenthere]

Jeff.

I can make a load calc say any btu I want, so the one given you could be faked or real, take the time to do your own.

Just awapping out parts to make it a smaller furnace? sounds like a cop out.

Doesn't carrier/bryant have a 100% satifction policy with their high end units.

[tommy graham]

--------1) He sounded like some of the more opinionated people here in his distaste for my duct system. Said that I'd never have a great system with the ducts I have (and yes, they told me that up front as well). I told him I was ok with that, and I understood, and all I want is a furnace that is somewhat matched to the duct system (this one just seems, well , way too big).-------



Jeff this the first time you have said anywhere in this post, now 19 pages, that they said some thing to you about the duct system, you have even been asked about this and you said "NO ONE HAD SAID ANYTHING ABOUT YOUR DUCT SYSTEM", and now you are changing boats saying they told you about this up front??? That is your whole problem with this furnace,the duct system, sounds to me like you went with LOW BALL PRICE......They told you that the furnace would not work properly with that duct system and you said "YOU WERE OK WITH THAT".....Live With IT or spend the BUCKS to correct it


“Tell me and I forget. Teach me and I remember. Involve me and I learn.”

[jeffw_00]

Read my posts. I've been clear and consistent. I was told by everyone who quoted to have limited expectations because of the duct system. I.e. it may be hard to fine-balance the temperatures from room to room, there may be some noise., etc. Basic message was not to expect the new system to perform any better than the old one. I was also told by everyone that they didn't see anything that could be done to correct the duct system.

Right now, I'm pretty happy with how the furnace is heating the house, if I damped down a few more ducts I'd be happy enough.

Problem is, with the current settings on the dampers, the cost of me being comfortable and somewhat happy is a short life for my furnace because the furnace is too big. If I can replace it with a furnace that gives me a little less heat, and the same CFM, I have now, and won't burn out in the process. I'm done.

i'm sorry you think I've been dishonest, or cheap.
/j

[dash]

Jeff,
What tonnage for cooling??

[jeffw_00]

Hi Dash - the A/C is 4-ton.

[jeffw_00]

Hi BT -
>>I can make a load calc say any btu I want, so the one given
>>you could be faked or real, take the time to do your own.

I don't think anyone played any games. They gave my plans to the guy at the supply house, who did a mechanical job.

>>Just awapping out parts to make it a smaller furnace? sounds
>> like a cop out.

If these things are really interchangable, I can see the logic - a lot easier than swapping a furnace, but I hear you guys saying this isn't std. op. procedure, so I won't let it happen.

>Doesn't carrier/bryant have a 100% satifction policy with
>their high end units.

probably, but this one was "legacy line". I'm -almost- ready to call bryant, but if I call them today I'm sure they'll tell me to let him visit first...

/thanks
/j

[beenthere]

How accessable are the supplies for the first floor?

[jeffw_00]

Originally posted by beenthere
How accessable are the supplies for the first floor?


now sure whar you're asking, but...

The A/C supplies are fully accessible from the Attic.
Most of heat supplies disappear into the walls very close to their start in the basement (see the picture I posted on, page 17 I think?)). No other access to them.

If I didn't answer the qn, ask it again.

/j

[dash]

Originally posted by jeffw_00

Originally posted by beenthere
How accessable are the supplies for the first floor?


now sure whar you're asking, but...

The A/C supplies are fully accessible from the Attic.
Most of heat supplies disappear into the walls very close to their start in the basement (see the picture I posted on, page 17 I think?)). No other access to them.

If I didn't answer the qn, ask it again.

/j

Separate A/C supplies?So no cooling with the furnace??