2-stage vs. single

[Cbssteve]

I was just wondering what is the bottom line on 2 stage vs. single stage cooling. Is it worth the investment in selling the 2 stage, or better off to go with the sinle stage condenser.

[AC Bad Dog]

I was just wondering what is the bottom line on 2 stage vs. single stage cooling. Is it worth the investment in selling the 2 stage, or better off to go with the sinle stage condenser.

You Can never be comfortable with a single stage AC. It is like buying a car where the gas pedal is an on/off switch.

The cooling load on a house is different every minute. How does a single stage even make sense?

Ask your customers who bought a 2 stage, They will be grateful. They spent a little more now for increased comfort for years and years.

ACBD

[Cbssteve]

So is it just there from a standpoint of comfort, or is there an energy savings as well?

[SBKold]

Yes in my opinion, you will see more $savings over a single stage. Hands down.

[teddy bear]

Making a home comfortable requires maintaining a narrow band of temperature and %RH. While the 2 speed or varible speed units are better than the single speed conventional a/c, they are unable to remove moisture without sensible cooling. The 2 speed/variable speed units are expensive and are complicated which is confirmed by the many posts trying to comfirm proper setup and preformance.
I promote combining a properly set-up simple a/c with a variable speed air handler and a whole house dehumidifier as the near perfect system to provide any temperature/%RH that the home may want.
During high cooling loads both systems are able to maintain temp/%RH. As the cooling loads decline to <50%, the two speed is able to decrease the cooling capacity to better match the cooling. Most two speeds are able to reduce 30-40% capacity. This reduces the off cycle which reduce the evaporation of the moisture collected on the cooling coil back to the home during the off cycle.
When cooling loads decline to less than several hours per day, the two speeds reach a point where over cooling occurs and must cycle off most of the nite and rainy/cool days. At this point 2spd a/cs are unable run long enough to move moisture from the home to the cooling coil and down the drain before the home is overcooled.
Compare this to a properly set up single speed a/c that cools to the t-stat set point while removing 30% latent heat (moisture) This 3-4 lbs. of moisture per ton per hour. This will maintain <50%RH during high/modrate cooling loads. The whole house dehumidifier will not be needed until the cooling cycle declines during the cool part of the day. When the %RH exceeds the set point, the dehu supplements the a/c to maintain %RH.

When the home is unoccupied for more than a couple hours, the whole house dehu will maintain <50%RH without any sensible cooling for a fraction of energy of the two speed a/c.
The other issue is that most home do not get enough fresh air during calm, warm weather naturally. The a/c industry avoid all possible fresh air because we are unable to maintain <50%RH when the outdoor dew points are +60^F and light cooling loads. With the ventilating whole house dehumidifier, we can provide the desired fresh air ventilation when the home is occupied while maintaining <50%RH.
Maintain the ideal temperature, most comfortable %RH, and healthy fresh air with moderate investment in equipment, maintaince, and operating cost. Most of our customers will prefer this results.
We add whole house dehus to many two speed systems to make customer satisfied. I work for Ultra-Aire and others.
Regards TB

[Cbssteve]

This is the type of answer I am looking for, thanks TB. I gather like a lot of people on the site say, it is good to use a dehumidifier with fresh air intake when cooling loads are low. Do you route this all into one control device, or do you need to use seperate controls?

[ga-hvac-tech]

My preference is to ALWAYS use a VS blower indoors... One can easily set up minor dehumidification with a VS blower.

Two stage AC is nice for specific needs... or for someone that wants the comfort enough to pay the extra.

I am currently doing a house with multiple systems, all will be VS blowers and 2 stage AC. The advantage the customer is paying the extra $$$ for is cooling capacity under different loads. If we have a mild summer... I doubt the systems will go into high much at all... If we have a hot summer, they will go into high most afternoons.

The other reason is these folks entertain. They may have 10-12 folks in the house on a Sat afternoon and/or evening... and that extra cooling capacity is really nice!

[teddy bear]

This is the type of answer I am looking for, thanks TB. I gather like a lot of people on the site say, it is good to use a dehumidifier with fresh air intake when cooling loads are low. Do you route this all into one control device, or do you need to use seperate controls?
I prefer separate controls because of the many unique ventilation options available for custom ventilation features. The Ultra-Aire DEH300 has time of day vent schedules for venting when occupied. For simple dehumidistat function, a t-stat with deh sat will work.
Regards TB

[2old2rock]

In my region, a VS blower with single stage A/C is fine.
Humid areas will benefit from 2 stage.

[jimj]

In my region, a VS blower with single stage A/C is fine.
Humid areas will benefit from 2 stage.

As will high sensible load areas like Arizona!

[beenthere]

I was just wondering what is the bottom line on 2 stage vs. single stage cooling. Is it worth the investment in selling the 2 stage, or better off to go with the single stage condenser.

That depends on what the customer wants. A customer truly interested in his/her comfort, yes its well worth the money.

One that just wants cold air, its not worth the money.

[kayjh]

This question is well on point for me. I am shopping for a central air system for the second time in 5 years. I live in the prairie region in Canada where we have July/August temperatures in the mid 80s (rarely high 80's) with a fairly dry climate (not as dry as Arizona but nowhere near as humid as Florida).

We have a 3,200 sq. ft. ranch style home that has radiant heat. We installed 2- 3 Ton units with duct work in the attic. the ductwork was double insulated and the air handlers are variable speed units. We have suffered with cold blasting air, high humidity (60%). I always believed we had too much capacity. The contractor assured me a Manual J had been completed and we might be a bit high, but were within the range of normal.

Finally, yesterday after 4 years of complaining, we sat down with the contractor who advised that he had a meeting with the wholesale supplier (who does all of the calculations after the measurements, etc are provided by the contractor) and it was determined that we have too much capacity. The wholesale supplier is going to stand behind the error and our equipment will be replaced this summer.

The question is, what to put in to replace the current system. I assume it will be Rheem equipment as that is what is there now (R22). I have been reading about 2 stage units, but one of the above posts seems to be saying they aren't necessary. I'm not sure I understand why a 2 stage system might also need a whole house dehumidified. I understand that if the unit is sized correctly, in combination with a variable speed motor, you should be able to get a good balance between temperature and humidity.

I appreciate though that you need to have the right size unit though. I was told that you must have a minimum of 400 cfm/ton, so with 3 tons, we are running 1,200 cfm minimum which creates significant airflow in the home and seems to hit the thermostat 5 minutes after the system starts, dropping the temperature quickly in the rooms and shutting it off.

The 2 stage system seems like it would be the perfect solution: In high load periods, 85F plus 20 people in the house, the 2 ton ( or 2.5 ton) x 2 units would run for a long period of time in stage 2 and at night when the temps drop the unit would run in stage 1 and would continue to run longer period (less cycling) and would dehumidify the house.

I feel a bit lost. How do I do this right the second time around? Do I select a 2 stage system? Is it necessary if the contractor sizes the 2 systems correctly? Do I need a whole house dehumidifier? We just want reduced draft, lower humidity and a comfortably cooled house - not a meat locker that is cold, drafty and clammy.

Any advice on this is appreciated. :) (I think I'm mostly on topic with the thread title, but if not I can start a new thread).

[AC Bad Dog]

This question is well on point for me. I am shopping for a central air system for the second time in 5 years. I live in the prairie region in Canada where we have July/August temperatures in the mid 80s (rarely high 80's) with a fairly dry climate (not as dry as Arizona but nowhere near as humid as Florida).

We have a 3,200 sq. ft. ranch style home that has radiant heat. We installed 2- 3 Ton units with duct work in the attic. the ductwork was double insulated and the air handlers are variable speed units. We have suffered with cold blasting air, high humidity (60%). I always believed we had too much capacity. The contractor assured me a Manual J had been completed and we might be a bit high, but were within the range of normal.

Finally, yesterday after 4 years of complaining, we sat down with the contractor who advised that he had a meeting with the wholesale supplier (who does all of the calculations after the measurements, etc are provided by the contractor) and it was determined that we have too much capacity. The wholesale supplier is going to stand behind the error and our equipment will be replaced this summer.

The question is, what to put in to replace the current system. I assume it will be Rheem equipment as that is what is there now (R22). I have been reading about 2 stage units, but one of the above posts seems to be saying they aren't necessary. I'm not sure I understand why a 2 stage system might also need a whole house dehumidified. I understand that if the unit is sized correctly, in combination with a variable speed motor, you should be able to get a good balance between temperature and humidity.

I appreciate though that you need to have the right size unit though. I was told that you must have a minimum of 400 cfm/ton, so with 3 tons, we are running 1,200 cfm minimum which creates significant airflow in the home and seems to hit the thermostat 5 minutes after the system starts, dropping the temperature quickly in the rooms and shutting it off.

The 2 stage system seems like it would be the perfect solution: In high load periods, 85F plus 20 people in the house, the 2 ton ( or 2.5 ton) x 2 units would run for a long period of time in stage 2 and at night when the temps drop the unit would run in stage 1 and would continue to run longer period (less cycling) and would dehumidify the house.

I feel a bit lost. How do I do this right the second time around? Do I select a 2 stage system? Is it necessary if the contractor sizes the 2 systems correctly? Do I need a whole house dehumidifier? We just want reduced draft, lower humidity and a comfortably cooled house - not a meat locker that is cold, drafty and clammy.

Any advice on this is appreciated. :) (I think I'm mostly on topic with the thread title, but if not I can start a new thread).

Hello,

Been there is right on. As you can see for yourself now, 2 stage = comfort.

Single stage = short cycles, high indoor RH, and no air moving thruogh your house or IAQ equipment. Just "cold air".

As for the Manual J, that is just Silly, No one knows the loads on old houses they just guess. And look at where you are at. Another reason to put in 2 stage.

BTW, this has nothing to do with where you live, it has to do with comfort.

Most folks have never experienced comfort because they have always had single stage equpment. Just wait til you see how comforatable you can be!


good luck!

AC BAD DOG





Good luck

[beenthere]

This question is well on point for me. I am shopping for a central air system for the second time in 5 years. I live in the prairie region in Canada where we have July/August temperatures in the mid 80s (rarely high 80's) with a fairly dry climate (not as dry as Arizona but nowhere near as humid as Florida).

We have a 3,200 sq. ft. ranch style home that has radiant heat. We installed 2- 3 Ton units with duct work in the attic. the ductwork was double insulated and the air handlers are variable speed units. We have suffered with cold blasting air, high humidity (60%). I always believed we had too much capacity. The contractor assured me a Manual J had been completed and we might be a bit high, but were within the range of normal.

Finally, yesterday after 4 years of complaining, we sat down with the contractor who advised that he had a meeting with the wholesale supplier (who does all of the calculations after the measurements, etc are provided by the contractor) and it was determined that we have too much capacity. The wholesale supplier is going to stand behind the error and our equipment will be replaced this summer.

The question is, what to put in to replace the current system. I assume it will be Rheem equipment as that is what is there now (R22). I have been reading about 2 stage units, but one of the above posts seems to be saying they aren't necessary. I'm not sure I understand why a 2 stage system might also need a whole house dehumidified. I understand that if the unit is sized correctly, in combination with a variable speed motor, you should be able to get a good balance between temperature and humidity.

I appreciate though that you need to have the right size unit though. I was told that you must have a minimum of 400 cfm/ton, so with 3 tons, we are running 1,200 cfm minimum which creates significant airflow in the home and seems to hit the thermostat 5 minutes after the system starts, dropping the temperature quickly in the rooms and shutting it off.

The 2 stage system seems like it would be the perfect solution: In high load periods, 85F plus 20 people in the house, the 2 ton ( or 2.5 ton) x 2 units would run for a long period of time in stage 2 and at night when the temps drop the unit would run in stage 1 and would continue to run longer period (less cycling) and would dehumidify the house.

I feel a bit lost. How do I do this right the second time around? Do I select a 2 stage system? Is it necessary if the contractor sizes the 2 systems correctly? Do I need a whole house dehumidifier? We just want reduced draft, lower humidity and a comfortably cooled house - not a meat locker that is cold, drafty and clammy.

Any advice on this is appreciated. :) (I think I'm mostly on topic with the thread title, but if not I can start a new thread).

My opinion differs from TB's. Most houses don't need a whole house dehumidifier.

With the over sized units you have now, your running in the 60s as far as humidity. Correctly sized units will bring that down into the 50s. And if they are single stage units with VS blowers, you will probably be able to get to the low 50s. 2 stage should be able to get you into the 40s, but obviously not that low every day.

Its also a falsehood that an A/C must move 400CFM per ton. My own is only moving 280 CFM per ton(don't ask your contractor to set your this low). Yes, I can only run it for about 20 minutes when its 70 outside. But in that 20 minutes, I can drop my indoor RH between 6 to 10% depending on outdoor conditions. I generally set my stat to 72, and run 48 to 50% RH.

If you want true comfort from your A/C, a 2 stage with VS blower, and a thermostat that can do cool to dehumidify, and slow the blower when the humidity is above set point during a normal cooling call..

[ScorpionLeather]

I had a 2 stage installed last year, and I would never go back to single stage. When the cool air is flowing continously it makes a nice breeze and as a result you can set the t-stat higher than you normally would. Imagine it's like a slight breeze on a hot day (2 stage running more continuously) vs. stale air on a hot day (1 stage cycling on and off).

[AC Bad Dog]

I had a 2 stage installed last year, and I would never go back to single stage. When the cool air is flowing continously it makes a nice breeze and as a result you can set the t-stat higher than you normally would. Imagine it's like a slight breeze on a hot day (2 stage running more continuously) vs. stale air on a hot day (1 stage cycling on and off).

Every one who gets a two stage finds this out.

Try a modulating furnace. It makes no difference what your silly load calc says
the unit will follow the load as it changes, a beautiful thing.

If we can get over this load calc crap and move on we will be well on our way. There is no correct load, nor does it matter.

AC BAD DOG

[beenthere]

Try a modulating furnace. It makes no difference what your silly load calc says
the unit will follow the load as it changes, a beautiful thing.


An over sized mod, doesn't keep the house as comfortable at mild outdoor temps, since it can only mod down so far.

[AC Bad Dog]

An over sized mod, doesn't keep the house as comfortable at mild outdoor temps, since it can only mod down so far.

OK

"Modulating Function: when used with a modulating or communicating thermostat, modulation rate between 40% and 100% of total capacity"

So my load can be between 40,000 and 100,000 BTU/H when I replace the existing 140,000 BTU/H furnace.

[beenthere]

OK

"Modulating Function: when used with a modulating or communicating thermostat, modulation rate between 40% and 100% of total capacity"

So my load can be between 40,000 and 100,000 BTU/H when I replace the existing 140,000 BTU/H furnace.

If you put a 100,000 in, your input can be between 40,000 and 100,000, without a load calc, no way to know what your load would be.

So if your actual load at design(say 0 outdoor temp) is 50,000BTUs and you install a 100,000 BTU, your not going to get long run times when its 40 degrees outside.

[AC Bad Dog]

If you put a 100,000 in, your input can be between 40,000 and 100,000, without a load calc, no way to know what your load would be.

So if your actual load at design(say 0 outdoor temp) is 50,000BTUs and you install a 100,000 BTU, your not going to get long run times when its 40 degrees outside.

Hey Beenthere,

How do you know your load is 50,000? You Don't. It could be 60,000 or it could be 40,000 depending on how you guessed on you Manual J. You don't know.

The point is you don't know the load, just a range at best. In the example you present the range is +-20%. Still does not matter what it is just that it changes. Put in a 60k.

Does not change the fact that the J provides no value in sizing if we need it only to differentiate between a 50,000 but heater and a 100,000 but heater.
I think you are making my point. It's a bit silly.

Peace

ACBD

[beenthere]

Hey Beenthere,

How do you know your load is 50,000? You Don't. It could be 60,000 or it could be 40,000 depending on how you guessed on you Manual J. You don't know.

The point is you don't know the load, just a range at best. In the example you present the range is +-20%. Still does not matter what it is just that it changes. Put in a 60k.

Does not change the fact that the J provides no value in sizing if we need it only to differentiate between a 50,000 but heater and a 100,000 but heater.
I think you are making my point. It's a bit silly.

Peace

ACBD

Why sell a furnace twice the size that is needed? Is it just to make more money?

The load at design doesn't change. Unless the customer makes changes to the home or their lifestyle.

[AC Bad Dog]

Why sell a furnace twice the size that is needed? Is it just to make more money?

The load at design doesn't change. Unless the customer makes changes to the home or their lifestyle.

Beenthere,

You would not.

Your manual J will tell you 40k with one set of guesses and 60k with another. Hardly a science project. You are guessing. You do not that @ 0 outside the load is 50,000. You cannot say that. Since these are your ranges of your guesses you make my point, it is not about the totals, only that loads change. Furnaces come in 20K increments so this is silliness.

Point is you do not know the load at any outside temp on an old house. You are guessing. Best I'll give you a range in your guess. 50,000 +- 20%. The tool you are using to get the number is not precise at all.

As discussed our industry is not held in high regard overall.

I hate contractors who rip off consumers, please don't go there.

AC BAD DOG

[ga-hvac-tech]

I guess someone needs to step in here, in defense of load calcs... since Seaton is gone... :)

Yes, there are lots of subjective things in a load calc... and yes, IMO there is really NO way to be absolutely accurate. However:

The house I am doing currently:
Roughly 7000 ft not including the basement
3 systems
3 VS furnaces (2-95%, 1-80%)
3 16 SEER 2 stage AC's
(Ruud equipment BTW)

I ran load calcs on each level... and found all three furnaces grossly too big. The AC loads were not too far off... and we did go a little large fort the main level AC on purpose because they entertain a lot. Also, there are 3 grade-school aged kids there (can you say in and out, leaving the door open... :) ).

IMO load calcs can give one a good idea, something maybe as close as within 10% of actual needs. The problem with load calcs is one cannot really know what is hidden in the walls... and that is significant... one can only guess.

After one has run dozens of load calcs, and seen the results of systems installed... and talked to the HO's after 6 mos, 1 year, etc... one can get a feel for what to look for, to make one's load calcs more accurate.

Still though... within 10% is about as accurate as they come IMO.

Thoughts?

[beenthere]

Beenthere,

You would not.

Your manual J will tell you 40k with one set of guesses and 60k with another. Hardly a science project. You are guessing. You do not that @ 0 outside the load is 50,000. You cannot say that. Since these are your ranges of your guesses you make my point, it is not about the totals, only that loads change. Furnaces come in 20K increments so this is silliness.

Point is you do not know the load at any outside temp on an old house. You are guessing. Best I'll give you a range in your guess. 50,000 +- 20%. The tool you are using to get the number is not precise at all.

As discussed our industry is not held in high regard overall.

I hate contractors who rip off consumers, please don't go there.

AC BAD DOG

The rip off is telling people to just get what ever size furnace like you suggest.

While furnaces come in 20,000 increments in a brand. By using 2 different brands, you have one in even inputs, and the other in odd inputs. Which gives you a much better selection. So that a house that needs a 62,000 BTU output, can have a furnace installed closest to that output.

If you don't want customers ripped off. Then they need a load calc done. And they'll get the comfort and savings they paid for.

[AC Bad Dog]

The rip off is telling people to just get what ever size furnace like you suggest.

While furnaces come in 20,000 increments in a brand. By using 2 different brands, you have one in even inputs, and the other in odd inputs. Which gives you a much better selection. So that a house that needs a 62,000 BTU output, can have a furnace installed closest to that output.

If you don't want customers ripped off. Then they need a load calc done. And they'll get the comfort and savings they paid for.

Hey Beenthere,

I just ran a Manual J on my house twice.

Once with a tight set of assumptions and one with loose. First time R30 in my attic next R19.

Depending on my guesses my heat loss is somewhere between 35,000 and 60,000 BTU/h. This is what I get with a manual J.What is "correct"?

So I just got a load done, two of them,now what?

What is right? How is the manual J science if this is the spread.

I have seen contractors using manual J come up with guesses of 3-5 tons on the same 2500 sq. ft house. Again, only your loads are right? what about the guy who did the same manual J and came up 1.5 tons higher?

Science? Come on,,witchcraft at best!

Thanks for playing.


Good luck,

AC BAD DOG

[ga-hvac-tech]

Hey Beenthere,

I just ran a Manual J on my house twice.

Once with a tight set of assumptions and one with loose. First time R30 in my attic next R19.

Depending on my guesses my heat loss is somewhere between 35,000 and 60,000 BTU/h. This is what I get with a manual J.What is "correct"?

So I just got a load done, two of them,now what?

What is right? How is the manual J science if this is the spread.

I have seen contractors using manual J come up with guesses of 3-5 tons on the same 2500 sq. ft house. Again, only your loads are right? what about the guy who did the same manual J and came up 1.5 tons higher?

Science? Come on,,witchcraft at best!

Thanks for playing.


Good luck,

AC BAD DOG

Just a thought there AC...

If the house currently has a 135,000 BTU natural draft furnace... a 70K or 75K or 80K furnace would be a HUGE savings.

On the AC side... a VS drive furnace with humidity control option set up will absorb some over-sizing.

[beenthere]

Hey Beenthere,

I just ran a Manual J on my house twice.

Once with a tight set of assumptions and one with loose. First time R30 in my attic next R19.

Depending on my guesses my heat loss is somewhere between 35,000 and 60,000 BTU/h. This is what I get with a manual J.What is "correct"?

So I just got a load done, two of them,now what?

What is right? How is the manual J science if this is the spread.

I have seen contractors using manual J come up with guesses of 3-5 tons on the same 2500 sq. ft house. Again, only your loads are right? what about the guy who did the same manual J and came up 1.5 tons higher?

Science? Come on,,witchcraft at best!

Thanks for playing.


Good luck,

AC BAD DOG


Maybe you wanna get away from the keyboard and go and see what you have in the attic.

Yep, I've seen Manual J's that are 5 tons for 2400 sq ft homes. the guy uses 1.2 for infiltration, and R9 for walls, and what ever low value for the attic. Too bad he didn't really check anything.

A load calc is like most anything else. if no real effort is put into it, then its results/benefits are just about useless.

[AC Bad Dog]

Just a thought there AC...

If the house currently has a 135,000 BTU natural draft furnace... a 70K or 75K or 80K furnace would be a HUGE savings.

On the AC side... a VS drive furnace with humidity control option set up will absorb some over-sizing.

Hey GA,

1.My house currently has a 4 ton WF geo unit, 2 Stage.(provided free from WF)

2.Prior to this it had a 3 ton Lennox XP19 with a 60k G61MVP VS gas Backup(provided free by Lennox)

3. Prior to this it had a 2.5 Ton Steller AC and a 80,000 P1UDD Furnace (provided free by York)

4. Prior to that house was built with 4 ton Rheem and 100,000 BTU Furnace

So, Four systems 4 different sizes all were correct, put in by the absolute best in the business, yet none of them did a load. Why is that Beenthere?

Repeat, Best designers there are in HVAC did the work. None did a Load! Why?

The guys who did my last 3 systems were hand picked by the manufacturers who gave me the systems. All three designers worked for the Manufacturer.

Maybe they know something!

AC BAD DOG

[ga-hvac-tech]

I cannot comment on what other shops do...

All I know is my customers are VERY satisfied and happy with my work. How happy: I literally do not advertise at all (I am not even in the YP), I have SO much referrals I sometimes cannot take care of them all. I also get to fire the worst few customers every year.

In over 30 years of running a small business, I have never had a BBB complaint, never had a bounced check, and never had a customer that wanted their $$$ back.

Can any of the folks who did your house truly say this...

[AC Bad Dog]

Maybe you wanna get away from the keyboard and go and see what you have in the attic.

Yep, I've seen Manual J's that are 5 tons for 2400 sq ft homes. the guy uses 1.2 for infiltration, and R9 for walls, and what ever low value for the attic. Too bad he didn't really check anything.

A load calc is like most anything else. if no real effort is put into it, then its results/benefits are just about useless.

I am happy to see you are so certain of uncertainty, it must be nice to know you are the one guy who's loads are correct, when all around you get different numbers. I wish i could feel that way. Unfortunately I have been ruined by hanging out with the best of the best. The top designers in HVAc have much less certainty in their answers than you do. I'll let these guys know, you duh man!

It must be nice to be able to know infiltration rates on old houses with such certainty when no one else can.

It must be great to know duct leakage rates without testing.

Can you see into walls?

Can you see dead people?

Thanks,

ACBD

[AC Bad Dog]

I cannot comment on what other shops do...

All I know is my customers are VERY satisfied and happy with my work. How happy: I literally do not advertise at all (I am not even in the YP), I have SO much referrals I sometimes cannot take care of them all. I also get to fire the worst few customers every year.

In over 30 years of running a small business, I have never had a BBB complaint, never had a bounced check, and never had a customer that wanted their $$$ back.

Can any of the folks who did your house truly say this...

Both my WF and Lennox provide incredible comfort.

Hard to get you money back when equipment and installs were free:)

AC BAD DOG

[kayjh]

My opinion differs from TB's. Most houses don't need a whole house dehumidifier.

With the over sized units you have now, your running in the 60s as far as humidity. Correctly sized units will bring that down into the 50s. And if they are single stage units with VS blowers, you will probably be able to get to the low 50s. 2 stage should be able to get you into the 40s, but obviously not that low every day.

Its also a falsehood that an A/C must move 400CFM per ton. My own is only moving 280 CFM per ton(don't ask your contractor to set your this low). Yes, I can only run it for about 20 minutes when its 70 outside. But in that 20 minutes, I can drop my indoor RH between 6 to 10% depending on outdoor conditions. I generally set my stat to 72, and run 48 to 50% RH.

If you want true comfort from your A/C, a 2 stage with VS blower, and a thermostat that can do cool to dehumidify, and slow the blower when the humidity is above set point during a normal cooling call..

AC Bad Dog, Beenthere,

Thanks for your posts. As you can tell, I'm just trying to educate myself a bit more this time around. Hopefully by doing so, I'll have a better dialog and better chance for success with the new AC system.

The 2 stage system seems like it does what our 5 year old Weil McLain modulating boiler does, combined with the Tekmar control system. We have a complicated system with 6 zones in our house, but each room is the same temperature and we never have an actual roomheat to thermostat variance of more than 1 degree Celsius in any room. In the shoulder season, we seen the boiler modulating at 10 - 20%. We have 230,000 BTU capacity which is a bit more than we ned, but we plan to in floor heat some additional 3 season rooms in the future.

As for the AC, I expect as you say that a whole house humidifier will not be necessary in our climate if we can just size the unit correctly and be able to have it operate for longer periods of time in "stage 1". This will lower our humidity, while at the same time remove the stuffiness in the air that seems to creep up when the system is between cooling cycles.

Does anyone ever mix some outside fresh air into a system (without the use of an HRV)? We have an "economizer" on our packaged unit at our ofice which will mix cool outside air into the system in the morning and late evenings to reduce compressor run times. I think it also adds fresh air into the office. I was just wondering whether it would be common to add a fresh air intake to our system. I'm assuming that if you want outside air to come in you'd need a way to get inside air to the outside?

Thanks for your posts. :)

[captube]

AC Bad Dog, Beenthere,

Thanks for your posts. As you can tell, I'm just trying to educate myself a bit more this time around. Hopefully by doing so, I'll have a better dialog and better chance for success with the new AC system.

The 2 stage system seems like it does what our 5 year old Weil McLain modulating boiler does, combined with the Tekmar control system. We have a complicated system with 6 zones in our house, but each room is the same temperature and we never have an actual roomheat to thermostat variance of more than 1 degree Celsius in any room. In the shoulder season, we seen the boiler modulating at 10 - 20%. We have 230,000 BTU capacity which is a bit more than we ned, but we plan to in floor heat some additional 3 season rooms in the future.

As for the AC, I expect as you say that a whole house humidifier will not be necessary in our climate if we can just size the unit correctly and be able to have it operate for longer periods of time in "stage 1". This will lower our humidity, while at the same time remove the stuffiness in the air that seems to creep up when the system is between cooling cycles.

Does anyone ever mix some outside fresh air into a system (without the use of an HRV)? We have an "economizer" on our packaged unit at our ofice which will mix cool outside air into the system in the morning and late evenings to reduce compressor run times. I think it also adds fresh air into the office. I was just wondering whether it would be common to add a fresh air intake to our system. I'm assuming that if you want outside air to come in you'd need a way to get inside air to the outside?

Thanks for your posts. :)

As far as the outside air there is discussion going on here..http://hvac-talk.com/vbb/showthread.php?t=828042

[teddy bear]

My opinion differs from TB's. Most houses don't need a whole house dehumidifier.

With the over sized units you have now, your running in the 60s as far as humidity. Correctly sized units will bring that down into the 50s. And if they are single stage units with VS blowers, you will probably be able to get to the low 50s. 2 stage should be able to get you into the 40s, but obviously not that low every day.

Its also a falsehood that an A/C must move 400CFM per ton. My own is only moving 280 CFM per ton(don't ask your contractor to set your this low). Yes, I can only run it for about 20 minutes when its 70 outside. But in that 20 minutes, I can drop my indoor RH between 6 to 10% depending on outdoor conditions. I generally set my stat to 72, and run 48 to 50% RH.

If you want true comfort from your A/C, a 2 stage with VS blower, and a thermostat that can do cool to dehumidify, and slow the blower when the humidity is above set point during a normal cooling call..

It takes 30 minutes to load a dry coil with enough mositure to start dripping down the drain. Roughly 1 lb. of moisture per ton of SEER 13 coils to load the coil. Yes the indoor %RH drops, but as the moisture left on the coil re-evaporates back into the home the %RH rises. If the dew point of the outside air is +60^F without a real cooling load, your indoor dew point will be as high as outside plus the moisture from the occupants. You have many hours of low/no cooling loads with high outdoor dew points.
Hope your customers do not get a fresh air change every 4-5 hours as recommended.
If your customers are fussy, they will not be happy depending on the weather they are exposed to. A good dehumidifier will maintain <50%RH regardless of the cooling load or the methically perfect sized a/c. I am currently removing 20 gals of moisture per week without any cooling while maintaining <50%RH in my finished basement. Hang on, you will be ok most of the time.
Regards TB

[beenthere]

Hey GA,

1.My house currently has a 4 ton WF geo unit, 2 Stage.(provided free from WF)

2.Prior to this it had a 3 ton Lennox XP19 with a 60k G61MVP VS gas Backup(provided free by Lennox)

3. Prior to this it had a 2.5 Ton Steller AC and a 80,000 P1UDD Furnace (provided free by York)

4. Prior to that house was built with 4 ton Rheem and 100,000 BTU Furnace

So, Four systems 4 different sizes all were correct, put in by the absolute best in the business, yet none of them did a load. Why is that Beenthere?

Repeat, Best designers there are in HVAC did the work. None did a Load! Why?

The guys who did my last 3 systems were hand picked by the manufacturers who gave me the systems. All three designers worked for the Manufacturer.

Maybe they know something!

AC BAD DOG

I met more then 1 factory guy that sized by sq ft. Doesn't make it or them right.

All 4 systems were not right, unless your house was added on to and or improvements made each time.

Doubt they all flew in the "best" designers in HVAC to do your units, and duct work.

[beenthere]

I am happy to see you are so certain of uncertainty, it must be nice to know you are the one guy who's loads are correct, when all around you get different numbers. I wish i could feel that way. Unfortunately I have been ruined by hanging out with the best of the best. The top designers in HVAc have much less certainty in their answers than you do. I'll let these guys know, you duh man!

It must be nice to be able to know infiltration rates on old houses with such certainty when no one else can.

It must be great to know duct leakage rates without testing.

Can you see into walls?

Can you see dead people?

Thanks,

ACBD


I can see why your an out of work comedian.

Duct leakage rate is easy to check in many homes, not all though.

Infiltration a bit harder.

Walls can be tested. If the customer wants to pay for the added time.

My on average 40% smaller then what was originally installed load calcs hasn't left a customer with poor heating or cooling. And has provided long run times like it should. Decreased energy bills in line with my estimate(not just 20% of my estimated savings, of course I don't tell them they are going to save a hundred bucks a month on cooling).

[beenthere]

AC Bad Dog, Beenthere,

Thanks for your posts. As you can tell, I'm just trying to educate myself a bit more this time around. Hopefully by doing so, I'll have a better dialog and better chance for success with the new AC system.

The 2 stage system seems like it does what our 5 year old Weil McLain modulating boiler does, combined with the Tekmar control system. We have a complicated system with 6 zones in our house, but each room is the same temperature and we never have an actual roomheat to thermostat variance of more than 1 degree Celsius in any room. In the shoulder season, we seen the boiler modulating at 10 - 20%. We have 230,000 BTU capacity which is a bit more than we ned, but we plan to in floor heat some additional 3 season rooms in the future.

As for the AC, I expect as you say that a whole house humidifier will not be necessary in our climate if we can just size the unit correctly and be able to have it operate for longer periods of time in "stage 1". This will lower our humidity, while at the same time remove the stuffiness in the air that seems to creep up when the system is between cooling cycles.

Does anyone ever mix some outside fresh air into a system (without the use of an HRV)? We have an "economizer" on our packaged unit at our ofice which will mix cool outside air into the system in the morning and late evenings to reduce compressor run times. I think it also adds fresh air into the office. I was just wondering whether it would be common to add a fresh air intake to our system. I'm assuming that if you want outside air to come in you'd need a way to get inside air to the outside?

Thanks for your posts. :)

I installed a few fresh air intakes on resi systems. I generally use an IAQ stat to control the damper for the intake. Aprilaire has a nice damper unit with its own control for this also.

[dan sw fl]

I guess someone needs to step in here, in defense of load calcs... since Seaton is gone... :)

Yes, there are lots of subjective things in a load calc... and yes, IMO there is really NO way to be absolutely accurate.

IMO load calcs can give one a good idea, something maybe as close as within 10% of actual needs. The problem with load calcs is one cannot really know what is hidden in the walls... and that is significant... one can only guess.

After one has run dozens of load calcs, and seen the results of systems installed... and talked to the HO's after 6 mos, 1 year, etc... one can get a feel for what to look for, to make one's load calcs more accurate.

Still though... within 10% is about as accurate as they come IMO.

Thoughts?

KISS - LOAD CALC ADDRESSES DESIGN CONDITION.

:whistle:
Design conditions exist for ~2% of the year.
9,000 ( 8,760 = 365 * 24) * 2% = 180 hours / year

So for maybe 5 hours a day 35 days a year, the load calcs give a representative idea of the capacity that is needed. ~ 12% accuracy in a load calc should be more than sufficent to make a satisfactory equipment selection.

:.02:
Loads probably change upto 30% in ~ 6 hours twice each day.
In other words, loads are CONSTANTLY Changing.

The remaining 8,400 ( 8,760 - 2* 180) hours a year the heating and cooling equipment may be in some sort of modulation or on-off mode.

THEREFORE, 2 stage seems to be an EXCELLENT idea for many climates.

I would Not be Strongly recommending 2-stage cooling for climates with < 1,000 Cooling Degree Days or MOD furnaces in the less demanding Southern climates.
... K.I.S.S.

NOW GO SELL YOUR 2-STAGE + VARIABLE SPEED EQUIPMENT to the CustOMers who wish to have C O M F O R T in ' their FORT'. ! !!

USE detailed Load Calcs without adding more margin to size equipment.

Only add margin for the customers who wish to address PARTY Time ( > 10 people )

[AC Bad Dog]

KISS - LOAD CALC ADDRESSES DESIGN CONDITION.

:whistle:
Design conditions exist for ~2% of the year.
9,000 ( 8,760 = 365 * 24) * 2% = 180 hours / year

So for maybe 5 hours a day 35 days a year, the load calcs give a representative idea of the capacity that is needed. ~ 12% accuracy in a load calc should be more than sufficent to make a satisfactory equipment selection.

:.02:
Loads probably change upto 30% in ~ 6 hours twice each day.
In other words, loads are CONSTANTLY Changing.

The remaining 8,400 ( 8,760 - 2* 180) hours a year the heating and cooling equipment may be in some sort of modulation or on-off mode.

THEREFORE, 2 stage seems to be an EXCELLENT idea for many climates.

I would Not be Strongly recommending 2-stage cooling for climates with < 1,000 Cooling Degree Days or MOD furnaces in the less demanding Southern climates.
... K.I.S.S.

NOW GO SELL YOUR 2-STAGE + VARIABLE SPEED EQUIPMENT to the CustOMers who wish to have C O M F O R T in ' their FORT'. ! !!

USE detailed Load Calcs without adding more margin to size equipment.

Only add margin for the customers who wish to address PARTY Time ( > 10 people )

Hey Dan,

Two guys go to visit a nice lady living in a 2400 sq. ft 2 story colonial house built in 1971 facing east/west currently with a broken 4 ton AC.

1st guy
Does the whole dog and pony show with his tape measurer, Wright=soft draw board, or maybe even his new Wrightsoft hand thing.
After 2 hours he has come up with a requirement of exactly 3.43785697312 tons. So he sells the nice lady a new 3.5 ton AC.

2nd Guy
Takes out a simple compass and shows the lady how the sun moves over her house and, my my, how she must have quite a bit of cooling around 4 pm when the sun is peaking on the back of her house.She explains to him that she already knows that because she lives there. He explains that loads are always changing and that is why he will replace her 4 ton with a new 4 ton two stage.


Which lady is Happier and More Comfortable?

Thanks,

ACBD

[kayjh]

Hey Dan,

Two guys go to visit a nice lady living in a 2400 sq. ft 2 story colonial house built in 1971 facing east/west currently with a broken 4 ton AC.

1st guy
Does the whole dog and pony show with his tape measurer, Wright=soft draw board, or maybe even his new Wrightsoft hand thing.
After 2 hours he has come up with a requirement of exactly 3.43785697312 tons. So he sells the nice lady a new 3.5 ton AC.

2nd Guy
Takes out a simple compass and shows the lady how the sun moves over her house and, my my, how she must have quite a bit of cooling around 4 pm when the sun is peaking on the back of her house.She explains to him that she already knows that because she lives there. He explains that loads are always changing and that is why he will replace her 4 ton with a new 4 ton two stage.


Which lady is Happier and More Comfortable?

Thanks,

ACBD

My question is if she had 4 ton and the calculation showed she needs 3.5 Ton, can you just put a 2 stage 4 Ton in and then if she had a bit too much cooling the system will operate in stage 1 most of the time and stage 2 when she is having a party or on an unusually hot day?

I'm curious to know if there is a tonnage equivalence that shows a 4 Ton operating a stage 2 is 4Ton and at stage one is ? Ton (is it 2 ton, 2.5 ton, 3 ton, etc.).

[teddy bear]

Hey Dan,

Two guys go to visit a nice lady living in a 2400 sq. ft 2 story colonial house built in 1971 facing east/west currently with a broken 4 ton AC.

1st guy
So he sells the nice lady a new 3.5 ton AC.

2nd Guy
with a new 4 ton two stage.

Which lady is Happier and More Comfortable?

Thanks,

ACBD

3rd guy
sells the a lady a new 4 ton with a whole house dehumidifier.
The sun sets and it rains for a couple days.
When the outside dew point is +60^F, 2 occupants add 1 lb. of moisture an hour when in the home. If the home is getting 80 cfm of fresh air infiltration/ventilation, 1 lb. of moisture will raise the dew point 6^F. With a 70^F home, a 66^F dew point equals 87%RH.
Without any significant cooling load, the dehu will maintain <50%RH regardless.
When the lady goes to town for a day or away for weeks, she sets the t-stat up to 80^F. The dehu maintains <50%RH for a few KWHs per day The electric bill is a fraction of VS A/c and the home is drier. If she desires top indoor air quality when the home is occupied, she includes fresh air ventilation option on the whole house dehumidifier.
10 years pass, she needs some repairs, Most techs can fix a simple a/c and dehu.

Which lady is happier?
Regards TB

[AC Bad Dog]

3rd guy
sells the a lady a new 4 ton with a whole house dehumidifier.
The sun sets and it rains for a couple days.
When the outside dew point is +60^F, 2 occupants add 1 lb. of moisture an hour when in the home. If the home is getting 80 cfm of fresh air infiltration/ventilation, 1 lb. of moisture will raise the dew point 6^F. With a 70^F home, a 66^F dew point equals 87%RH.
Without any significant cooling load, the dehu will maintain <50%RH regardless.
When the lady goes to town for a day or away for weeks, she sets the t-stat up to 80^F. The dehu maintains <50%RH for a few KWHs per day The electric bill is a fraction of VS A/c and the home is drier. If she desires top indoor air quality when the home is occupied, she includes fresh air ventilation option on the whole house dehumidifier.
10 years pass, she needs some repairs, Most techs can fix a simple a/c and dehu.

Which lady is happier?
Regards TB

Mr. Bear,

The customers buying 2 Stage will all tell you they are much more comfortable.Ask them. Their system will run almost 85% of the time on 1st Stage, gently moving air all the time, can you here the background music?

This lady has a single stage now, and she knows not only the pain of over oversizing but also the nature of on/off equipment. True, the simple equipment is simpler to Fix.

But when ladies' coterie runs late into the afternoon and the ladies start drinking JD and smoking cigars isn't it nice to know your system has another gear?

Now who is happiest?

ACBD

[dan sw fl]

Hey Dan,

Two guys go to visit a nice lady living in a 2400 sq. ft 2 story colonial house built in 1971 facing east/west currently with a broken 4 ton AC.

1st guy
Does the whole dog and pony show with his tape measurer, Wright=soft draw board, or maybe even his new Wrightsoft hand thing.
After 2 hours he has come up with a requirement of exactly 3.43785697312 tons. So he sells the nice lady a new 3.5 ton AC.

2nd Guy
Takes out a simple compass and shows the lady how the sun moves over her house and, my my, how she must have quite a bit of cooling around 4 pm when the sun is peaking on the back of her house.She explains to him that she already knows that because she lives there. He explains that loads are always changing and that is why he will replace her 4 ton with a new 4 ton two stage.

Which lady is Happier and More Comfortable?

EXPERIENCE WINS > 84 % OF THE TIME !

It doesn't matter what "the game" is.

[beenthere]

EXPERIENCE WINS > 84 % OF THE TIME !

It doesn't matter what "the game" is.

More like the second guy came in and told her she needs a 5 ton, and ignored the fact that the duct work is under sized for 4 tons.

[AC Bad Dog]

More like the second guy came in and told her she needs a 5 ton, and ignored the fact that the duct work is under sized for 4 tons.

1st Guy spent a lot of time dancing around measuring, and pretending to do a scientific study. Except he doesn't know any of the inputs,his measurements are +- 10% on area, his window area measurements are over by 30%, he knows the least of all on the two most important inputs, AHC and System looses(except for Beenthere who has super powers). His play act produces a spreadsheet that says she needs a 3.45456787656564534 ton unit.

2nd Guy correctly states loads change every second and no one knows what they are at any given second(except beenthere). He also tells her something she already knows, that late in the day she has a peak cooling condition. Nice lady can relate to this as she lives in the house. 2nd guy makes the sale, puts in a nice 4 ton 2 stage. Happy customer, profitable sale.

2nd guy, looked customer in the eye and told them the truth.

1st guy, tried to "differentiate" himself with his J manual broadway musical.

Scientist with his J manual complains about the lack of expertise in his business. But lost the job to a guy who put in a better system. How's that work?

I want the guy who has already done 100 houses like mine. Why would he need to another parlor act on the 101st?

ACBD

[ga-hvac-tech]

Hey Dan,

Two guys go to visit a nice lady living in a 2400 sq. ft 2 story colonial house built in 1971 facing east/west currently with a broken 4 ton AC.

1st guy
Does the whole dog and pony show with his tape measurer, Wright=soft draw board, or maybe even his new Wrightsoft hand thing.
After 2 hours he has come up with a requirement of exactly 3.43785697312 tons. So he sells the nice lady a new 3.5 ton AC.

2nd Guy
Takes out a simple compass and shows the lady how the sun moves over her house and, my my, how she must have quite a bit of cooling around 4 pm when the sun is peaking on the back of her house.She explains to him that she already knows that because she lives there. He explains that loads are always changing and that is why he will replace her 4 ton with a new 4 ton two stage.


Which lady is Happier and More Comfortable?

Thanks,

ACBD

Third guy comes in... FIRST, he asks the customer about their experience with the current equipment... in their opinion how well it cools, how well it heats, does it circulate air well, are there hot/cold rooms, does it make too much noise (inside and outside)... etc, etc, etc. Then the HVAC professional asks the customer what they like and dislike about the current system. Then he asks questions to see what features the customer would like to have in a new system.

After discussion, the third guy asks if they can walk around and look at the current system. As the looking process proceeds, more questions and a few suggestions based on observations. Each time a suggestion is made, the reaction to the suggestion is mentally noted.

IMO, only AFTER the HVAC professional has asked and received input from the customer as to what they have, what they like/dislike, what they need, and what they want, as well as looking over the existing equipment, ductwork and installation... is he qualified to suggest a replacement system.

In conclusion; To say this or that is always the right thing to do... is kinda like saying a chevy truck will meet the needs of every driver on the road. Now we know a soccer-mom and many a real estate agent would not do well with a truck... so the idea of one shoe fits all is just not wise IMO.

Now I have a question for AC Bad Dog: Are you a licensed HVAC professional in your area, and BTW: what is your area... I do not see a location on your posts nor in your profile? If you are a licensed Pro, may I suggest you apply for Pro status. The REAL discussions on this board happen in the Pro area... and it appears you might have some information to contribute. The site has links to pro status... easy to find.

[beenthere]

2nd Guy correctly states loads change every second and no one knows what they are at any given second(except beenthere). He also tells her something she already knows, that late in the day she has a peak cooling condition. Nice lady can relate to this as she lives in the house. 2nd guy makes the sale, puts in a nice 4 ton 2 stage. Happy customer, profitable sale.


Because the third guy came in did his load calc. Found that the customer could make a few simply economical improvements to his home so that instead of needing a 3.5 ton, he would only need a 3 ton, and the third guy recommended a 3 ton 2 stage that provides better savings and comfort.

And with the extra money that the customer saved on not having to have his duct work increased to handle and over sized 4 ton 2 stage or pay for the over sized 4 ton 2 stage, he was able to pay for those few home improvements. And saves money in both heating and cooling season.

[AC Bad Dog]

Because the third guy came in did his load calc. Found that the customer could make a few simply economical improvements to his home so that instead of needing a 3.5 ton, he would only need a 3 ton, and the third guy recommended a 3 ton 2 stage that provides better savings and comfort.

And with the extra money that the customer saved on not having to have his duct work increased to handle and over sized 4 ton 2 stage or pay for the over sized 4 ton 2 stage, he was able to pay for those few home improvements. And saves money in both heating and cooling season.

Guy(with the magic powers to know the exact inputs) did his super duper load calc was able to let the lady know with total confidence that at the exact design conditions he used the cooling load would be 41,456.567463475667998865466 BTU/hr. And this exact condition would occur for about 47 seconds over the next 12 months. Every other second the load would be different than the "precise" load. For most of the seconds there would be no load at all, when there was a load the vast majority of the time it would be less than 2/3 of his calculation and small percentage of the time it would be more.

The lady was confused. Why was this guy so hung up on determining a number that lasts 97 seconds a year. Why was he not interested in her actual operating conditions? Why not calculate her operating loads if he was concerned about "accuracy". If he believes his own BS why not use ASHRAE methodology, or radiant time series to calculate these numbers. Why is he using the most primitive spreadsheet available? It all seams like an oxymoron.

The whole thing starts to look silly.

Guy with the compass has the happiest customers, makes more money, and is putting in better systems. Load Guy is using his toy to validate what he already knows.

This ladies house is exactly like 3000 other houses in this neighborhood. They were all built by Pulte at the exact same time. After we have done 400,500, 600, loads and they are all exactly the same can we now assume we have them pretty well figured or should we continue this charade further?

Anyone knows the manual J does a very simple overstated Calc, and has many flaws. Lets watch one man's review.

http://homeenergypros.lbl.gov/video/home-energy-efficiency

ACBD

[beenthere]

Guy(with the magic powers to know the exact inputs) did his super duper load calc was able to let the lady know with total confidence that at the exact design conditions he used the cooling load would be 41,456.567463475667998865466 BTU/hr. And this exact condition would occur for about 47 seconds over the next 12 months. Every other second the load would be different than the "precise" load. For most of the seconds there would be no load at all, when there was a load the vast majority of the time it would be less than 2/3 of his calculation and small percentage of the time it would be more.

The lady was confused. Why was this guy so hung up on determining a number that lasts 97 seconds a year. Why was he not interested in her actual operating conditions? Why not calculate her operating loads if he was concerned about "accuracy". If he believes his own BS why not use ASHRAE methodology, or radiant time series to calculate these numbers. Why is he using the most primitive spreadsheet available? It all seams like an oxymoron.

The whole thing starts to look silly.

Guy with the compass has the happiest customers, makes more money, and is putting in better systems. Load Guy is using his toy to validate what he already knows.

This ladies house is exactly like 3000 other houses in this neighborhood. They were all built by Pulte at the exact same time. After we have done 400,500, 600, loads and they are all exactly the same can we now assume we have them pretty well figured or should we continue this charade further?

Anyone knows the manual J does a very simple overstated Calc, and has many flaws. Lets watch one man's review.

http://homeenergypros.lbl.gov/video/home-energy-efficiency

ACBD

So why use the first guy that is guessing, and over sizing the unit for even the highest load the house will see during the year. Makes no sense.

Guy with the compass is costing his customers money every year. if any of his customers are happy. Its because ignorance is bliss. And they don't have any idea how much money they would be saving if they went with the guy that did the load calc.

[Willserve]

Hey Dan,

Two guys go to visit a nice lady living in a 2400 sq. ft 2 story colonial house built in 1971 facing east/west currently with a broken 4 ton AC.

1st guy
Does the whole dog and pony show with his tape measurer, Wright=soft draw board, or maybe even his new Wrightsoft hand thing.
After 2 hours he has come up with a requirement of exactly 3.43785697312 tons. So he sells the nice lady a new 3.5 ton AC.

2nd Guy
Takes out a simple compass and shows the lady how the sun moves over her house and, my my, how she must have quite a bit of cooling around 4 pm when the sun is peaking on the back of her house.She explains to him that she already knows that because she lives there. He explains that loads are always changing and that is why he will replace her 4 ton with a new 4 ton two stage.


Which lady is Happier and More Comfortable?

Thanks,

ACBD

So how does the 2nd guy come up with a 4 ton two stage. Is he just going off what they had? What's your base line for new construction. Square footage, what the people next door put in, what? You have to start somewhere or do you use http://www.hvaccomputer.com/hvac/sizer.asp.

[AC Bad Dog]

So why use the first guy that is guessing, and over sizing the unit for even the highest load the house will see during the year. Makes no sense.

Guy with the compass is costing his customers money every year. if any of his customers are happy. Its because ignorance is bliss. And they don't have any idea how much money they would be saving if they went with the guy that did the load calc.

J Guys loves his toy, has a big investment in it in Money, Time, and personally. I certainly understand his resistance to being confronted with reality.

Compass Guy did not sell savings, he sold comfort. He knows how much the HVAC sales guys game their software and way oversell savings. He knows SEER is BS. He sells comfort, and beats J guy and gets the sale way more than J guys knows or can accept. J guys is going to save customer 20% of what he told the customer, ask your power company. They know this.


It is a fact that the loads change every sec.
It is a lie they are any given number.

Also Ask your Utility Buddies about the load calcs they get from all the Manual J experts and how different one experts loads are from the other(except Beenthere's who' loads are what we compare too). After they get done rolling their eyes, Ask them how oversized they are from the operating loads they see.

You just watched an analysis of just how bad the J is verses reality, why not upgrade to one of the better models? Why use the most primitive?

Since Manual J loads are way over, this translates of course to way overstated savings. You can even use manufactured loads to push HP's or Gas depending on how you set up the heating to cooling. More heating vs Cooling higher balance point gas looks better. Higher cooling loads to heating loads get Larger Heat pumps, lowers balance point, so HP op costs are lower than gas. All depends on what you want to sell.

Folks have been using the load calc sales ritual for years. Man J is a sales tool. lets also bring back the Sling Psychrometer! That was a good one too!

ACBD

[beenthere]

Compass Guy did not sell savings, he sold comfort. He knows how much the HVAC sales guys game their software and way oversell savings. He knows SEER is BS. He sells comfort, and beats J guy and gets the sale way more than J guys knows or can accept. J guys is going to save customer 20% of what he told the customer, ask your power company. They know this.


Compass guy sold a box, cause he doesn't take the time to check things. Or he would have known the duct system is too small for a 4 ton A/C.

He seldom loses bids, cause he's the cheapest guy. And he constantly can't afford to return for warranty calls. And never admits he's gets lots of complaints of high humidity, cause 2 stage units don't have great latent ability in first stage. But he continues to over size, cause its not his house, and he thinks he makes a few dollars more by over sizing.

[AC Bad Dog]

Compass guy sold a box, cause he doesn't take the time to check things. Or he would have known the duct system is too small for a 4 ton A/C.

He seldom loses bids, cause he's the cheapest guy. And he constantly can't afford to return for warranty calls. And never admits he's gets lots of complaints of high humidity, cause 2 stage units don't have great latent ability in first stage. But he continues to over size, cause its not his house, and he thinks he makes a few dollars more by over sizing.

Not Quite,

While J guys was playing with his computer Compass guy was talking with customer and looking at the system.

Still haven't heard why J guy uses absolute worst model if he is really committed to modeling? Why not use a better more tool they are certainly out there? Why Is the dumbed down model the toy choice?

ACBD

[Willserve]

Bad Dog,

J Guys loves his toy, has a big investment in it in Money, Time, and personally. I certainly understand his resistance to being confronted with reality. Maybe we should spend more money on saleman that upsell people things they don't need or want.

Compass Guy did not sell savings, he sold comfort. He knows how much the HVAC sales guys game their software and way oversell savings. He knows SEER is BS. Aren't most 2 speed a/c's higher SEER than single speed? What's the SEER of your free 2 speed a/c compared to the other free one's , ask your power company. They know this.

It is a fact that the loads change every sec.
It is a lie they are any given number.

Also Ask your Utility Buddies about the load calcs they get from all the Manual J experts and how different one experts loads are from the other(except Beenthere's who' loads are what we compare too). That's kind of funny because our Utility Buddies hold manual J and D classes every year to provide a better energy and comfort service for our customers.After they get done rolling their eyes, Ask them how oversized they are from the operating loads they see.

You just watched an analysis of just how bad the J is verses reality, why not upgrade to one of the better models? Why use the most primitive?

Since Manual J loads are way over, this translates of course to way overstated savings. You can even use manufactured loads to push HP's or Gas depending on how you set up the heating to cooling. More heating vs Cooling higher balance point gas looks better. Higher cooling loads to heating loads get Larger Heat pumps, lowers balance point, so HP op costs are lower than gas. All depends on what you want to sell.

Folks have been using the load calc sales ritual for years. Man J is a sales tool. lets also bring back the Sling Psychrometer! That was a good one too!
I'm with you brother, those old ways of doing stuff right is ridicules or as you say silly. When those doctors, dentists, and mechanics come out with those old manuals I'm like seriously, your using all that old data, research and experience to treat me or fix my car. Come on all that old stuff is so silly
ACBD

[AC Bad Dog]

Bad Dog,

I am glad you guys are able to believe in your toys, I still can't figure out why you keep telling me how great you model homes, yet why are you using the worst model? How about an upgrade?

As I said I am too jaded by reality. If you are trying to tell me that the manual j dog and pony show is not used as part of a sales pitch I have some land in Florida for you.

If you are trying to tell me contractors don't back into the numbers they want you don't get out much.

If you are trying to tell me all the contractors doing loads get the same number or even close, you have never been out at all.

If you are trying to tell me this is science, you are insulting scientists.

It does seam a emotional issue for some of you.

Sorry I touched a sore nerve, keep playing with your toys it they make you happy. And keep believing you are the one who's loads are "right".

And let me know why you prefer the J to the more sophisticated models.
On the one hand, you are a perfectionist but you use the worst tool available. No doctor would use leaches anymore even though they were once popular.

ACBD

[ga-hvac-tech]

Quote from a poster above:

Still can't get an answer For why use the most primitive model if we believe in Model
(end quote)



Interesting...

Seems one poster is fussing over another poster not answering a question... while that same fussing poster chooses to ignore a question posed to them...

Wonder what that choice of behavior is called in the real world?

[beenthere]

Not Quite,

While J guys was playing with his computer Compass guy was talking with customer and looking at the system.

Still haven't heard why J guy uses absolute worst model if he is really committed to modeling? Why not use a better more tool they are certainly out there? Why Is the dumbed down model the toy choice?

ACBD

Compass guy only took the time to look at his compass and tell the customer that they needed a 4 ton 2 stage. You said so in the original post you talked about him. So he never looked at the system, as that would have required more then a compass to tell what alterations the duct work needs to handle 4 tons.

He sells 2 stage at the same price as others sale single stage with a VS blower.

Manual J is a compressed digest of AHRAE. Its easier to use it then go through everything in long form as ASHRAE has it.

You like to guess and say it doesn't matter. Compass guy guesses, and installs over sized equipment on under sized duct work, and his customers have loud systems.


There are countless threads on the board, where basically compass guy went to a home and simply sold a large unit, and never looked at anything but what way the house faces. So those people have loud systems, and are not comfortable. Even those that were sold a 2 stage unit by compass guy, aren't happy. Go look at the threads.

[ga-hvac-tech]

Too bad Josh Seaton is gone... he would have had a field day with this thread.... :)

[AC Bad Dog]

Now I have a question for AC Bad Dog: Are you a licensed HVAC professional in your area, and BTW: what is your area... I do not see a location on your posts nor in your profile? If you are a licensed Pro, may I suggest you apply for Pro status. The REAL discussions on this board happen in the Pro area... and it appears you might have some information to contribute. The site has links to pro status... easy to find.

OK Ga, I'll answer your question,

I am a Software guy, Business Trainer, and Motivational Speaker.We have two teams of software developers. One group builds savings calculators, lead generation tools, and HVAC design tools and the other team builds High End Contractor Websites, does SEM, and related marketing functions for larger HVAC companies, HVAC Distributors, and Manufacturers. I know more HVAC companies than anyone. They are my friends and brothers. They are also going through some fundamental changes in our business. The small guys are getting their asses handed to them by sophisticated marketers, and very few even know this is happening.

I built my 1st Load Calc software 33 years ago in Collage and have been involved in 6 more load calc programs since. I have trained roughly 7000 HVAC professionals how to use the manual J. My company built the AHRI upload and validation system. We are also the ones who turned AHRI in to the Fed for falsifying third party coil ratings. We also built the software to calculate AFUE. I have been very blessed and thankful to have participated in this business and have great respect for all those small contractors out there fighting for survival.

The HVAC industry has been very good to me.
I have had a very unique perspective. And it is true I have become a little cynical. For instance; Did you know the folks who produce Manual J software pay a 7% royalty to ACCA. This adds up to big bucks but of course "its not about the money".

I hope I have answered your question, apologies for not answering it the 1st time you asked me.

Thank you for your invitation to join your pro group. I would be happy to participate, but also feel that much of our discussion needs to be in the public view.

There is the answer to your question, still waiting for mine.

AC BAD DOG

[ga-hvac-tech]

THX for the explanation AC Dog,

If you have been around H-talk for long, you probably have seen what we call trolls... folks that know literally NOTHING about HVAC, yet dominate a conversation and talk as though they are the final authority... most of them are HO's that have engineering degrees. The ONE thing we always see with these self proclaimed experts is: They do not put any information in their profile... they like to be anonymous.

I do not mean this to be accusatory... however you were sounding like one of the above.... My apologies for prodding you.

As a side note: I use a version of load calc software for specific needs. I do not use it on all homes, however there are specific issues I like to use it to resolve. And I have had a few customers request a calc... which I am glad to provide (results will be provided AFTER they sign a contract for me to do the work).

Now as to your question... was it directed at me? If so, please re-state it and I will be glad to do what I can to answer it.

[AC Bad Dog]

Compass guy only took the time to look at his compass and tell the customer that they needed a 4 ton 2 stage. You said so in the original post you talked about him. So he never looked at the system, as that would have required more then a compass to tell what alterations the duct work needs to handle 4 tons.

He sells 2 stage at the same price as others sale single stage with a VS blower.

Manual J is a compressed digest of AHRAE. Its easier to use it then go through everything in long form as ASHRAE has it.

You like to guess and say it doesn't matter. Compass guy guesses, and installs over sized equipment on under sized duct work, and his customers have loud systems.


There are countless threads on the board, where basically compass guy went to a home and simply sold a large unit, and never looked at anything but what way the house faces. So those people have loud systems, and are not comfortable. Even those that were sold a 2 stage unit by compass guy, aren't happy. Go look at the threads.

Hey Beenthere,

You are guessing too.If its all about the math why not use ASHRAE. This method will give you the loads over each hour(oh yea, you don't care about that). It will also let you see the effects of heating offsets, and many other time dependent variables. You make all these speeches about loads and doing things right and then use the children's version of ASHRAE?

I am happy you like your Manual J, good for you. I am also amazed at your super human powers of knowing the exact infiltration rates, system efficiency losses and other variables you know for sure while other mortals must guess at. I have never met another human with these qualities.

I think you should keep doing your science projects and believing in you.

I will always take the guy with experience over the guy with the computer.

I have been lucky to work first hand with the absolute best designers in HVAC. I have watched them, and learned from them.

Good Luck to you,

AC BAD DOG

[beenthere]

Hey Beenthere,

You are guessing too.If its all about the math why not use ASHRAE. This method will give you the loads over each hour(oh yea, you don't care about that). It will also let you see the effects of heating offsets, and many other time dependent variables. You make all these speeches about loads and doing things right and then use the children's version of ASHRAE?

I am happy you like your Manual J, good for you. I am also amazed at your super human powers of knowing the exact infiltration rates, system efficiency losses and other variables you know for sure while other mortals must guess at. I have never met another human with these qualities.

I think you should keep doing your science projects and believing in you.

I will always take the guy with experience over the guy with the computer.

I have been lucky to work first hand with the absolute best designers in HVAC. I have watched them, and learned from them.

Good Luck to you,

AC BAD DOG

Maybe if you actually worked in HVAC and did load calcs and installed and tested the systems. You would know more of how it works in the real world. Not just in your house, or by paper reports you have seen.

[beenthere]

No one installs a 4 ton duct system when they are installing a 3.5 ton unit. And the vast majority are on under sized duct work to begin with. I've been installing and servicing for a long time.

[ga-hvac-tech]

The problem with engineering... is things do not always work the same way in real life as they do on paper.

Ask any engineer that has done field work most of their career (especially in construction), and they will tell you the paper guys do not know what they are talking about.

[AC Bad Dog]

Maybe if you actually worked in HVAC and did load calcs and installed and tested the systems. You would know more of how it works in the real world. Not just in your house, or by paper reports you have seen.

hey beenthere, chill out....

Your feathers are a little ruffled.

I have worked in HVAC for 33 years and I guarantee you I have done many, many more manual j calculations than just about anyone. I have also taught over 7000 HVAC professionals how to do the Manual J both on new houses and existing ones. I developed my first manual j software in Collage and have worked on 6 other Manual J programs over the last 30 years.I also know more HVAC companies than anybody. I know a little about the "real word" you speak of.

Thank you however for your insults,

AC BAD DOG

[just_opinion]

5 pages of same Sh%$ when AC Mad Dog and beenthere are dicussing (I remember it happen last July 2010 with the same sh^%$) - Manual J or Not Manual J. And I love it. Keep on AC Mad Dog. Fight on Mr. Moderator. :bump:

By the way may I ask 2 of you one question each:

AC Mad Dog : When you get to the house that has 4 tons system and you look at the sunset and sun rise per said you, Then you sold that nice lady a 4 tons 2 stages. Who AND HOW he came up with that original 4 tons for you to follow ?

Beenthere: If the manual J said 2.5 tons, then just ignore the fact that the old unit served this customer for 25 years with no discomfort. You'll say that it is wrong to sell her a 3 tons 2 stages because the HVAC bible of yours says 2.5 tons.

I personally uses manual J and other guessing manuals. But I am not holding it like an ABSOLUTE bible.

But fight on. I meant dicuss on :bump:

[beenthere]

hey beenthere, chill out....

Your feathers are a little ruffled.

I have worked in HVAC for 33 years and I guarantee you I have done many, many more manual j calculations than just about anyone. I have also taught over 7000 HVAC professionals how to do the Manual J both on new houses and existing ones. I developed my first manual j software in Collage and have worked on 6 other Manual J programs over the last 30 years.I also know more HVAC companies than anybody. I know a little about the "real word" you speak of.

Thank you however for your insults,

AC BAD DOG

My feathers aren't ruffled. But it appears yours are.

You already saidl that about knowing all those HVAC companies and people earlier in the thread. And writing your first J program, and the 6 others before. And you also said the same thing in your thread last year. No need to keep repeating yourself. Most of us have read that other thread of yours. Your just continuing that thread in this thread.

The real world you know of. Is not the real world of doing. You don't design and install. Others do. As you said, others designed the system for your house, you didn't.

[beenthere]

5 pages of same Sh%$ when AC Mad Dog and beenthere are dicussing (I remember it happen last July 2010 with the same sh^%$) - Manual J or Not Manual J. And I love it. Keep on AC Mad Dog. Fight on Mr. Moderator. :bump:

By the way may I ask 2 of you one question each:

AC Mad Dog : When you get to the house that has 4 tons system and you look at the sunset and sun rise per said you, Then you sold that nice lady a 4 tons 2 stages. Who AND HOW he came up with that original 4 tons for you to follow ?

Beenthere: If the manual J said 2.5 tons, then just ignore the fact that the old unit served this customer for 25 years with no discomfort. You'll say that it is wrong to sell her a 3 tons 2 stages because the HVAC bible of yours says 2.5 tons.

I personally uses manual J and other guessing manuals. But I am not holding it like an ABSOLUTE bible.

But fight on. I meant dicuss on :bump:

LOL... You forgot, I also know how to use Manual S. Along with T and D.

[beenthere]

5 pages of same Sh%$ when AC Mad Dog and beenthere are dicussing (I remember it happen last July 2010 with the same sh^%$) - Manual J or Not Manual J. And I love it. Keep on AC Mad Dog. Fight on Mr. Moderator. :bump:

By the way may I ask 2 of you one question each:

AC Mad Dog : When you get to the house that has 4 tons system and you look at the sunset and sun rise per said you, Then you sold that nice lady a 4 tons 2 stages. Who AND HOW he came up with that original 4 tons for you to follow ?

Beenthere: If the manual J said 2.5 tons, then just ignore the fact that the old unit served this customer for 25 years with no discomfort. You'll say that it is wrong to sell her a 3 tons 2 stages because the HVAC bible of yours says 2.5 tons.

I personally uses manual J and other guessing manuals. But I am not holding it like an ABSOLUTE bible.

But fight on. I meant dicuss on :bump:

ACBD's thread on the same thing last year, went on for 19 pages.

[ga-hvac-tech]

Hmmm, Seems to me AC Puppy with your experience you would know a load calc is to determine the size necessary to meet design temps... which are 'reasonable extremes' for a given area.

Here is an example of what I do: Design temps for Atlanta GA are listed as summer 92 and winter 21. I size for summer 95-96 and winter 20, as anyone around here knows we have a few summers in the low 90's... but most of them have lots of afternoons in the high 90's, and a few days over 100. I also ask the customer what temps they consider comfortable in their home.

Example: I have some customers that literally want their home to feel like a meat locker... I mean literally between 68-70 all summer... and I used to service a chemistry lab that MUST maintain 70+/- 1D year round.

The equipment is VERY different for folks that need/want these extremes, as folks that are comfortable with 75-78.

Now back to load calcs: A house with a specific heat loss/heat gain at given design winter/summer, will need a specific ability to add/remove BTU's. If the equipment chosen is capable of adding or removing that amount of BTU's, then that equipment is adequate for the load. A 2 stage furnace, and either a 2 stage AC or a VS drive furnace with dehum cycle, will handle the load nicely.

What I find repeatedly is: a furnace that is anywhere between 1/2 to 2 times what is necessary... and an AC that is at least 1 ton too large. Also I find many times a house where the windows, doors, and insulation have been upgraded. Obviously that improved house does not need as much capacity to add or remove BTU's.

On a recent install, I replaced a 135K input furnace and 4 ton AC with a 75K 95% furnace (VS, 2 stage) and a 3 ton AC with dehum cycle. The HO was raving about how much better the house felt, how much quieter the system was, how the master bdrm was comfortable for the first time, etc, etc, etc. The only ductwork mods I did was add an extra 10" flex return, and a 20x25 media filter (AirBear).

The customer literally could not keep quiet about how GREAT the system is... and I now have 2 referrals on my desk from him. And anyone who has been in sales knows: A referral is WAAAY better than a cold call... one goes in the door as the good guy... rather than just another guy. I close most of my referral sales... with minimal hassle.

So IMO load calcs do have their place... however I will agree that they are not rocket science... and they are not a god... Rather, they are just another tool... like a dual port manometer for static pressure testing... or a DB/WB thermometer.

[ga-hvac-tech]

ACBD's thread on the same thing last year, went on for 19 pages.

The only topic I can think of tonite that is more controversial than Man J is combustion analysis...

Each fall we have a bunch of threads about CA or not... And each year I learn more about CA.

I think I have learned some more about Man J this time around... and I have re-learned that engineers who do not have any 'hands on' experience... still do not know much of what really goes in in our trade.

[just_opinion]

LOL... You forgot, I also know how to use Manual S. Along with T and D.


ACBD's thread on the same thing last year, went on for 19 pages.

3 more bibles, opps, I meant manuals and 13 more pages to go :cheers:

I am glad this not not a space-shuttle-talk.com

[AC Bad Dog]

My feathers aren't ruffled. But it appears yours are.

You already saidl that about knowing all those HVAC companies and people earlier in the thread. And writing your first J program, and the 6 others before. And you also said the same thing in your thread last year. No need to keep repeating yourself. Most of us have read that other thread of yours. Your just continuing that thread in this thread.

The real world you know of. Is not the real world of doing. You don't design and install. Others do. As you said, others designed the system for your house, you didn't.

You are right, others did design my house, and never once even looked at a computer to do this. The WF guys nor the Lennox guys did not need that crutch, they were way past that.

I have however designed lots of houses, mostly large custom jobs for rich folks and many tract houses for larger builders back in the day. I am quite certain my HVAC design skills are real world. I know first hand when your Manual J program says I need one 6' hit in the bonus room over the garage I need to put in 2 or we will have a cold and angry customer.

You are also correct that i have never installed an air conditioner or hung duct. They won't even let me touch the power tools. My background does give me enough experience to know how bogus your load calcs can be and certainly expose the truths about these myths you are selling.

You keep harping on all this exact load calc crap yet you still are using and promoting a dumbed down children's version of the program. You are incorrect in your assessment of the Hourly programs. You have also stated guys who sell 2 stage are cheaper.You have made statements that look out of touch with real world RNC. Makes me wonder a little about just how much you really have been there?

You claim some sort of superiority due your use of a computer program. Is that your only claim to fame, you can use a computer. Come to think of it, you probably do need it. I think we agree!

Best of luck,

ACBD

[Willserve]

So if we bought your a/c software we would be much better at determining unit size and load calcs because that's what all the big a/c companies use. It is one of those secrets that only the Big Dogs know. So if you can go on this forum and convince everyone that the Manual J is old school and out dated you can sell more of your software, is that the game. I think the manual J, field experience and common sense are the best things out there. I use all three and haven't had any complaints about under or over sizing equipment. BTW I don't bring a compass, I'm pretty sure of the house's orientation before I get there.

[beenthere]

So if we bought your a/c software we would be much better at determining unit size and load calcs because that's what all the big a/c companies use. It is one of those secrets that only the Big Dogs know. So if you can go on this forum and convince everyone that the Manual J is old school and out dated you can sell more of your software, is that the game. I think the manual J, field experience and common sense are the best things out there. I use all three and haven't had any complaints about under or over sizing equipment. BTW I don't bring a compass, I'm pretty sure of the house's orientation before I get there.


When he starts pitching his software again, then the pitch will be removed from this thread.

[beenthere]

You are right, others did design my house, and never once even looked at a computer to do this. The WF guys nor the Lennox guys did not need that crutch, they were way past that.

I have however designed lots of houses, mostly large custom jobs for rich folks and many tract houses for larger builders back in the day. I am quite certain my HVAC design skills are real world. I know first hand when your Manual J program says I need one 6' hit in the bonus room over the garage I need to put in 2 or we will have a cold and angry customer.

You are also correct that i have never installed an air conditioner or hung duct. They won't even let me touch the power tools. My background does give me enough experience to know how bogus your load calcs can be and certainly expose the truths about these myths you are selling.

You keep harping on all this exact load calc crap yet you still are using and promoting a dumbed down children's version of the program. You are incorrect in your assessment of the Hourly programs. You have also stated guys who sell 2 stage are cheaper.You have made statements that look out of touch with real world RNC. Makes me wonder a little about just how much you really have been there?

You claim some sort of superiority due your use of a computer program. Is that your only claim to fame, you can use a computer. Come to think of it, you probably do need it. I think we agree!

Best of luck,

ACBD



I claim no fame. I don't claim to know the best designers around, or the best installers.

I do however though use a GPS to get from one place to another, instead of a compass, but I still carry a compass with me. And I do use a computer/laptop for load calcs.

I botched my first real world load calc 30 years ago. Haven't made the same mistakes again since though.

[teddy bear]

Now back to load calcs: A house with a specific heat loss/heat gain at given design winter/summer, will need a specific ability to add/remove BTU's. If the equipment chosen is capable of adding or removing that amount of BTU's, then that equipment is adequate for the load. A 2 stage furnace, and either a 2 stage AC or a VS drive furnace with dehum cycle, will handle the load nicely.
a dual port manometer for static pressure testing... or a DB/WB thermometer.

I have a VS drive 3 stage furnace with a dehum cycle. I asked the sales rep, will this control %RH. Pretty much, was the answer. When the tech followed the install with final set-up, I asked the tech the same question. He said that if there was a enough cooling that with a 3^F overcool possibly would reach 50%RH. He set the air flow to 1/2 ton less than the a/c size and said this was the best he could do. All ready this year, the house has reached +60%RH without any cooling load.
I have fired up my dehumidifier and am removing 10-20 gals of moisture per week to maintain <50%RH. Is my a/c not setup right or are you guys pulling our leg about a/c with a dehumidifier cycle being able to maintain <50%RH during wet cool weather?
My experience with a/c weither 2 cycle or dehumidifier cycle, they are unable to maintain <50%RH during wet cool weather.
With a whole house dehumidifier, oversize or undersized a/c need not even run to maintain <50%RH at a fraction of operating cost. Puffery or a honest mistake?
Regards TB

[beenthere]

I have a VS drive 3 stage furnace with a dehum cycle. I asked the sales rep, will this control %RH. Pretty much, was the answer. When the tech followed the install with final set-up, I asked the tech the same question. He said that if there was a enough cooling that with a 3^F overcool possibly would reach 50%RH. He set the air flow to 1/2 ton less than the a/c size and said this was the best he could do. All ready this year, the house has reached +60%RH without any cooling load.
I have fired up my dehumidifier and am removing 10-20 gals of moisture per week to maintain <50%RH. Is my a/c not setup right or are you guys pulling our leg about a/c with a dehumidifier cycle being able to maintain <50%RH during wet cool weather?
My experience with a/c weither 2 cycle or dehumidifier cycle, they are unable to maintain <50%RH during wet cool weather.
With a whole house dehumidifier, oversize or undersized a/c need not even run to maintain <50%RH at a fraction of operating cost. Puffery or a honest mistake?
Regards TB

Your A/C is over sized, and not set up right.

[teddy bear]

Your A/C is over sized, and not set up right.

Really, my house has not reached +70^F yet, how is the setup have anything to do with it.
It this the best you got. The outside dew points are up to 68^F. The moisture from two occupants and no cooling load, "My a/c is not set up right".
Sounds like the salesman-Yep,this a/c will handle moisture, pretty much.
Looking to here more. I got data loggers to measure inside/outside. Inside moisture levels are same as outside plus the mositure added by the occupants. The key to your success is that your customers understand-no cooling load, no dehumidification. This makes sense to me. While a dehumidifier with a good a/c equals <50%RH regardless the cooling load. This is critical with a finished basement. Nice in slab home.
Regards TB

[beenthere]

Your early post about your then 'new' system you even said it was over sized.

Next. Did you ever tell the salesman that was at your house that you keep your windows open almost anytime the outdoor temp is below 75? Probably not. Did you tell him you will be using the basement air as your main return? I doubt it. Did you tell him you would be using your dehumidifier to bring in lots of high humidity fresh air? Probably not.

You set him up. And you are trying to use it for a stepping stone to sell whole house dehumidifiers.

My house seldom reaches 70 with our current weather, but I can keep the humidity down with my A/C. How, I don't open the windows and let high humidity air in. And I don't bring in fresh high humidity air all the time like you do. I run a 26°F temp drop across my coil(closer to 28 on some of these mild days) at 280 CFM per ton, on a 2.5 ton A/C. Gives me lots of latent, with not a lot of sensible capacity.

[beenthere]

Really, my house has not reached +70^F yet, how is the setup have anything to do with it.
It this the best you got. The outside dew points are up to 68^F. The moisture from two occupants and no cooling load, "My a/c is not set up right".
Sounds like the salesman-Yep,this a/c will handle moisture, pretty much.
Looking to here more. I got data loggers to measure inside/outside. Inside moisture levels are same as outside plus the mositure added by the occupants. The key to your success is that your customers understand-no cooling load, no dehumidification. This makes sense to me. While a dehumidifier with a good a/c equals <50%RH regardless the cooling load. This is critical with a finished basement. Nice in slab home.
Regards TB

Less then 50% isn't required. Its nice but but a necessity. So its not critical.

[ga-hvac-tech]

I have a VS drive 3 stage furnace with a dehum cycle. I asked the sales rep, will this control %RH. Pretty much, was the answer. When the tech followed the install with final set-up, I asked the tech the same question. He said that if there was a enough cooling that with a 3^F overcool possibly would reach 50%RH. He set the air flow to 1/2 ton less than the a/c size and said this was the best he could do. All ready this year, the house has reached +60%RH without any cooling load.
I have fired up my dehumidifier and am removing 10-20 gals of moisture per week to maintain <50%RH. Is my a/c not setup right or are you guys pulling our leg about a/c with a dehumidifier cycle being able to maintain <50%RH during wet cool weather?
My experience with a/c weither 2 cycle or dehumidifier cycle, they are unable to maintain <50%RH during wet cool weather.
With a whole house dehumidifier, oversize or undersized a/c need not even run to maintain <50%RH at a fraction of operating cost. Puffery or a honest mistake?
Regards TB

Compared to an oversized single stage on a PSC motor, it is a HUGE improvement.

Not everyone will spend the BIG bucks for all the bells and whistles... Many folks all they will buy is VS and a media. One would have to admit that is an improvement over builder grade... :)

[AC Bad Dog]

When he starts pitching his software again, then the pitch will be removed from this thread.

Hey Beenthere

Clearly,You are the only one selling software here. Are you on the payroll?

Over and over you are shamelessly hawking Manual J software. Not me but you.I have not said a word. Your constantly shilling manual J software is quite unbecoming. Should you stop your own sales pitch? You have been quite eager to criticize software you know nothing about. Quite eager to make comments without any knowledge. Can you only give it? All our software has/will been provided free. No exceptions. If you ever want to compare one to the other I am quite certain we will kick your J up one side of the street and down the other. Want to bet?


You loose me and others when you make statements that clearly are not true.


Where you lose all credibility is when you state that you know the variables.

You do not know the infiltration rates of an old house bud,the blower door gang knows how silly that statement is. Making a claim like that is False.Does not help your case.

You do not know the the duct loss or leakage. Again to say you do is false. NCI has all kind of protocol to test this but you have no clue by looking. Again, you do not know this, and saying you do defies logic and undermines you credibility.

You do not know wall values or any of the other inputs to your manual J.

How can we take you seriously when you make such statements.

Clearly you need your manual j for security and as part of your sales pitch.
I am glad you know how to use a computer and make inputs into your spreadsheet. You also seem to have a need to validate your needs by selling this to others.
You loose me when you state you know what the inputs are, you don't. That is just not true, why say that?

Unfortunately, you are also wrong about our software, is has and will continue to be given away for free. Did you know ACCA gets 7% kickback on all the J manual stuff your selling. You? Of course its not about the money.

If you ever want to have a software cook off, I'm game.We are way ahead of that old tool. We will provide every player free software to test real houses vs their Manual J or any other software. How about that? Want to find out reality?

You will learn just how bad your guesses really can be. But that would interfere with the "reality" you have created.


Let me repeat, we will provide every member of this board evolutionary software free. Players must simply agree to run comparisons vs their Manual J or wherever software they use and report back to this forum. That's It.

Want to play? Want to put up, Shut up?

Or is it time to turn the thread off and run?

Looking forward to your reply,

ACBD

[kayjh]

hey beenthere, chill out....

Your feathers are a little ruffled.

I have worked in HVAC for 33 years and I guarantee you I have done many, many more manual j calculations than just about anyone. I have also taught over 7000 HVAC professionals how to do the Manual J both on new houses and existing ones. I developed my first manual j software in Collage and have worked on 6 other Manual J programs over the last 30 years.I also know more HVAC companies than anybody. I know a little about the "real word" you speak of.

Thank you however for your insults,

AC BAD DOG

What is the Collage you've been to? Some people here have probably been to College, but I've never heard of a Collage.

[HP41CV]

Less then 50% isn't required. Its nice but but a necessity. So its not critical.

In a perfect world, I'd keep it at 40%. My guitars and piano are happiest there, as I am.

[beenthere]

Not on anyone's payroll. Not hawking anyone's software.

As far as I know, you never provided the software to the member that replied in your thread last year.

[beenthere]

In a perfect world, I'd keep it at 40%. My guitars and piano are happiest there, as I am.

Things like Pianos and Guitars are a different subject when it comes to RH.

Reheat pips and hot and cold decks are used in commercial applications where humidity control for objects is critical.

[airsys]

In my area Manual J & D are required for Green Point certification. They don't anything about other software that is not ACCA approved.

[beenthere]

In my area Manual J & D are required for Green Point certification. They don't anything about other software that is not ACCA approved.

I believe there are several areas that the program "Must" be ACCA approved.

[Willserve]

AC Bad Dog keeps quoting this "Where you lose all credibility is when you state that you know the variables." Am I missing something? When doing a whole house laod calc the only variable I can't see is the external wall insulation between inner and outer wall. I can usually tell if the floor is concrete or wood, I can see and meassure attic insulation, ducts, roof, ceiling, walls, windows, floor covering etc. A little research and you can find out what code was for min during that time frame. Some input dosn't change the the final numbers very much. Obviously there is no money in developing your own manual J software so you do the next best thing, discredit whats already out there and boost up what your selling as the newest, greatest, mo-better thing on the market.

[ga-hvac-tech]

Seems to me someone that does not have Pro status is digging themselves a DEEP hole... Hope they do not fall into it... or loose their posting privileges.

Remember this is a private site where posting is not a right.

[teddy bear]

Your early post about your then 'new' system you even said it was over sized.

Next. Did you ever tell the salesman that was at your house that you keep your windows open almost anytime the outdoor temp is below 75? Probably not. Did you tell him you will be using the basement air as your main return? I doubt it. Did you tell him you would be using your dehumidifier to bring in lots of high humidity fresh air? Probably not.

You set him up. And you are trying to use it for a stepping stone to sell whole house dehumidifiers.

My house seldom reaches 70 with our current weather, but I can keep the humidity down with my A/C. How, I don't open the windows and let high humidity air in. And I don't bring in fresh high humidity air all the time like you do. I run a 26°F temp drop across my coil(closer to 28 on some of these mild days) at 280 CFM per ton, on a 2.5 ton A/C. Gives me lots of latent, with not a lot of sensible capacity.
You are right about the setup. You are wrong about the open windows. I have not opened a window since I hooked up the make-up air ventilating dehumidifier.
But your mind set is the same as the a/c salesman. He could not imagine high indoor humidity without a significant cooling load. Sholder seasons and summer have a lot of weather with +60^F dew points and no cooling load. This spring, I have spent time with out make-up air ventilation to calculate the natural ventilation with varible winds and occasional high/temps. The actual amount of infiltrating fresh air has varied from 10 cfm during calm up to 40 cfm of fresh air during moderate wind. This is an air change in a couple days during calm weather. With several in a home during low air change, the moisture added by the occupants builds up in the home to the points condensation on the cool surfaces in the basement or on the slab. Indoor pollutants are high and the oxygen content declines. A problem with closed windows in a air tight home.
Turn on the dehumidifier makes it comfortable but stale yet. The dehumidifier removes moisture from the occupants and the moisture from a small amount of fresh air.
Now the perfect home with good heating/cooliing maintaining temperature. A whole house ventilating dehumidifier providing 60-75 cfm of fresh air when the home is occupied and maintaining <50%RH or whatever you want. House is fresh and comfortable! MY BAD????
The a/c salesman does not want to here about it because he could not imagine the possiblilty of the problem. Is he an open minded guy?? He know that he can not admit that the latest, greatest a/c will not solve all of the problems?? So be it. The market will decide long term, more homeowner must pay big bucks for the latest complicated systems without getting the implied comfort plus the total avoiding of the fresh air that is required by all indoor air quality codes and many state codes.
On a more pleasnt note, thanks for participating in this much needed airing of this indoor air quality/comfort problem. I trust that your a sincere person, but only missguided.
Regards TB

[just_opinion]

Hey Beenthere

Clearly,You are the only one selling software here. Are you on the payroll?

Over and over you are shamelessly hawking Manual J software. Not me but you.I have not said a word. Your constantly shilling manual J software is quite unbecoming. Should you stop your own sales pitch? You have been quite eager to criticize software you know nothing about. Quite eager to make comments without any knowledge. Can you only give it? All our software has/will been provided free. No exceptions. If you ever want to compare one to the other I am quite certain we will kick your J up one side of the street and down the other. Want to bet?


You loose me and others when you make statements that clearly are not true.


Where you lose all credibility is when you state that you know the variables.

You do not know the infiltration rates of an old house bud,the blower door gang knows how silly that statement is. Making a claim like that is False.Does not help your case.

You do not know the the duct loss or leakage. Again to say you do is false. NCI has all kind of protocol to test this but you have no clue by looking. Again, you do not know this, and saying you do defies logic and undermines you credibility.

You do not know wall values or any of the other inputs to your manual J.

How can we take you seriously when you make such statements.

Clearly you need your manual j for security and as part of your sales pitch.
I am glad you know how to use a computer and make inputs into your spreadsheet. You also seem to have a need to validate your needs by selling this to others.
You loose me when you state you know what the inputs are, you don't. That is just not true, why say that?

Unfortunately, you are also wrong about our software, is has and will continue to be given away for free. Did you know ACCA gets 7% kickback on all the J manual stuff your selling. You? Of course its not about the money.

If you ever want to have a software cook off, I'm game.We are way ahead of that old tool. We will provide every player free software to test real houses vs their Manual J or any other software. How about that? Want to find out reality?

You will learn just how bad your guesses really can be. But that would interfere with the "reality" you have created.


Let me repeat, we will provide every member of this board evolutionary software free. Players must simply agree to run comparisons vs their Manual J or wherever software they use and report back to this forum. That's It.

Want to play? Want to put up, Shut up?

Or is it time to turn the thread off and run?

Looking forward to your reply,

ACBD

What !
Are we gonna let this hanging like this. I am just getting to the climax AND .... It is like the ending of some porn movies. :grin2:

We still got 10 more pages to go to beat the last thread. Well, technically 11 more pages. Because ACMD used a whole page for his biography (If he happened to click and pasted the bible, we'd still be here reading it). :grin2:

Anyway, where is the fire ??? Where is MY moderators?

[AC Bad Dog]

What !
Are we gonna let this hanging like this. I am just getting to the climax AND .... It is like the ending of some porn movies. :grin2:

We still got 10 more pages to go to beat the last thread. Well, technically 11 more pages. Because ACMD used a whole page for his biography (If he happened to click and pasted the bible, we'd still be here reading it). :grin2:

Anyway, where is the fire ??? Where is MY moderators?

Mr. Opinion,

Sorry to ruin your fun but I have to concede, Beenthere is right. He knows you guys better than me. There were no takers on our offer. I give up.

The ties in the board rooms of Carrier Corp describe the difference as the "Businessman" vs the "tool belt". The larger and More sophisticated a contractor gets the more you are dealing with someone who knows and thinks business.You are talking to folks who think sales, marketing, finance, and the like. The little one man shops tend to be more tool belt focused.Nothing wrong with either. Obviously it is the business skill set that is required to get big and lack of that keeps many one man shops small.

Think about it, we just licensed our brand new Home Energy Audit and HVAC Design software to an electric and gas utility that owns 2 large HVAC companies for $150,000.00. The software gives them a significant competitive advantage over the the smaller companies they compete against. We make an offer to give the same software for free to all the "professionals" on this site no one wants to look.Oh well, at least we tried. We made the offer.

Beenthere is right, many already know everything, their glass is full, no more room for new info. THey made a mistake 30 years ago and corrected it. He also correctly predicted none of you guys would want to see any new systems or approaches to your processes. OK, we made the offer, it was rejected.


To me it is all a bit sad. The little guys are really getting beat up badly by the larger, increasingly sophisticated marketing oriented contractors, big box retailers, utilities,internet retailers, etc. They end up with what is left after the best customers have been taken. We were trying to help, we failed.

Sorry Mr. Opinion for taking up your time,


ACBD

[ga-hvac-tech]

Mr. Opinion,

Sorry to ruin your fun but I have to concede, Beenthere is right. He knows you guys better than me. There were no takers on our offer. I give up.

The ties in the board rooms of Carrier Corp describe the difference as the "Businessman" vs the "tool belt". The larger and More sophisticated a contractor gets the more you are dealing with someone who knows and thinks business.You are talking to folks who think sales, marketing, finance, and the like. The little one man shops tend to be more tool belt focused.Nothing wrong with either. Obviously it is the business skill set that is required to get big and lack of that keeps many one man shops small.

Think about it, we just licensed our brand new Home Energy Audit and HVAC Design software to an electric and gas utility that owns 2 large HVAC companies for $150,000.00. The software gives them a significant competitive advantage over the the smaller companies they compete against. We make an offer to give the same software for free to all the "professionals" on this site no one wants to look.Oh well, at least we tried. We made the offer.

Beenthere is right, many already know everything, their glass is full, no more room for new info. THey made a mistake 30 years ago and corrected it. He also correctly predicted none of you guys would want to see any new systems or approaches to your processes. OK, we made the offer, it was rejected.


To me it is all a bit sad. The little guys are really getting beat up badly by the larger, increasingly sophisticated marketing oriented contractors, big box retailers, utilities,internet retailers, etc. They end up with what is left after the best customers have been taken. We were trying to help, we failed.

Sorry Mr. Opinion for taking up your time,


ACBD

The question now becomes: Who does the better quality install: The HUGE shop that is interested in profits... or the little shop that is interested in quality? Note that I am not knocking the larger shops... however I have sold for a large shop, and have seen the way the accts cut corners. Honestly, I would not let them install a window shaker on my puppy house.

Sorry AC Puppy, however GM got into a mess by letting accts cut the quality of their product... and they deserve to be a ward of the govt... Ford, on the other hand, made quality the focus and are still free...

Go figure.

[just_opinion]

Mr. Opinion,

... The software gives them a significant competitive advantage over the the smaller companies they compete against. We make an offer to give the same software for free to all the "professionals" on this site no one wants to look.....

ACBD

I did not reject the offer.
You can send me the package via my email in my personal profile.

[Mr Bill]

Obviously it is the business skill set that is required to get big and lack of that keeps many one man shops small.

Actually, Mr. Bill stay's small because he like's it better that way, the smaller, the less drugs we have to take, I am so small I don't even drink, much less take any drugs, now that's small.... :grin2: :grin2: :grin2:

[htroberts]

If you want true comfort from your A/C, a 2 stage with VS blower, and a thermostat that can do cool to dehumidify, and slow the blower when the humidity is above set point during a normal cooling call..

So, do you really mean a *variable* speed blower, or a multi-speed blower? How many speeds do multi-speed blowers have? Just two? Select one for maximum dehumidification and one for full-capacity cooling?

If it's really variable (i.e. continuously variable), how is it controlled (not with simple relay outputs, I'm guessing)?

What's an example of a thermostat that can "cool to dehumidify"?

[htroberts]

Point is you do not know the load at any outside temp on an old house. You are guessing. Best I'll give you a range in your guess. 50,000 +- 20%. The tool you are using to get the number is not precise at all.


Could you find it experimentally? Start with the house at a known temperature, and then, on a cold day, add heat at a known rate and see how the temp drops, then compare that to the temp drop with no added heat?

This seems impractical, to say the least, mostly just a thought experiment.

[htroberts]

If we can get over this load calc crap and move on we will be well on our way. There is no correct load, nor does it matter.


Of course there's a "correct" load. It's just only correct at one particular set of conditions, and the building/system operate under very different conditions at different times...

By convention, we size for something like 90% of peak load, because that's the best compromise between efficiency and not keeping up on hot days. That means that most of the time, fixed-capacity systems are "too big" and cost more to operate than they should.

Modulating equipment makes possible a better match between instantaneous load and capacity, but with the trade-off of added complexity.

Even if you use modulating equipment, you still need to know the range of loads you can expect on different days so you can size the equipment to be efficient (in terms of capital and operating costs).

[beenthere]

So, do you really mean a *variable* speed blower, or a multi-speed blower? How many speeds do multi-speed blowers have? Just two? Select one for maximum dehumidification and one for full-capacity cooling?

If it's really variable (i.e. continuously variable), how is it controlled (not with simple relay outputs, I'm guessing)?

What's an example of a thermostat that can "cool to dehumidify"?

Variable, not multispeed.

The Honeywell IAQ, and the newer Th8321 can both slow a VS blower down.

Slowing a multispeed blower down, you don't know what CFM you'll get. With a VS, you know what CFM you'll get.

[just_opinion]

Variable, not multispeed.

The Honeywell IAQ, and the newer Th8321 can both slow a VS blower down.

Slowing a multispeed blower down, you don't know what CFM you'll get. With a VS, you know what CFM you'll get.

I have not used HW IAQ stat. Does it have the PWM to control the blower speed analogically ?

[beenthere]

I have not used HW IAQ stat. Does it have the PWM to control the blower speed analogically ?


No, it uses a set of dry contacts to slow the blower through the hum terminal of the blower control board.

So its not brand specific.

[chuckcrj]

I have not used HW IAQ stat. Does it have the PWM to control the blower speed analogically ?

No, just use BK or dehum or whatever terminal slows the VS fan.

Never mind BT beat me.

[just_opinion]

No, it uses a set of dry contacts to slow the blower through the hum terminal of the blower control board.

So its not brand specific.

I know this is off the topic of this thread. And I want ACMD and you guys with Manual J to continue on ... What a thrill !

Anyway ..

So, typically these so called variable speed motor is being DIGITIZED.

[beenthere]

I know this is off the topic of this thread. And I want ACMD and you guys with Manual J to continue on ... What a thrill !

Anyway ..

So, typically these so called variable speed motor is being DIGITIZED.

A VS motor generally varies its speed to maintain set CFM. The control boards also have a terminal that will signal the motor to slow down when it is not energized.

Some are controlled by PWM, the Afinity/Evolution line for one.

[ga-hvac-tech]

Most of the VS motors are ECM (electronically commutated motors), they come from GenTeq corporation, formerly a division of GE. The '2' series (2.0, 2.2, 2.3, 2.5), had the logic (PWN) on the furnace board with a 16 wire harness to the motor. The new 3.0 still has the logic on the board, however it communicates with the board without the 16 wire harness... The board has the specific to unit (specific furnace) logic in a chip on the board.

As BT says: The advantage of the VS motor is constant CFM's. Google Genteq and read up on it.

[AC Bad Dog]

I did not reject the offer.
You can send me the package via my email in my personal profile.

Mr Opinion,

You are the only one from this site to take us up on our offer to join the user driven software club.
We are now at 300 companies(mostly larger dealers, lots of GEo guys) who will be testing and helping develop a new generation of Home Audit Software. It also does a before and after Manual J.

Conditions:

1.Contactualy, We can't allow any company with an address within 150 miles of 100 Love RD Reading PA to use this software. This is the corporate office of the Utility that funded the project. As stated this tool creates a significant competitive advantage.

2. There are 70,000 lines of code and heavy graphics.You will need to upgrade your browser to the latest version. Or better yet use FireFox. We run great and Macs and I Pads.

3. Share your experience on this board.

If this conditions are acceptable I will get you a login.


Thanks for playing,

ACBD

[teddy bear]

Mr Opinion,

You are the only one from this site to take us up on our offer to join the user driven software club.
We are now at 300 companies(mostly larger dealers, lots of GEo guys) who will be testing and helping develop a new generation of Home Audit Software. It also does a before and after Manual J.

Conditions:

1.Contactualy, We can't allow any company with an address within 150 miles of 100 Love RD Reading PA to use this software. This is the corporate office of the Utility that funded the project. As stated this tool creates a significant competitive advantage.

2. There are 70,000 lines of code and heavy graphics.You will need to upgrade your browser to the latest version. Or better yet use FireFox. We run great and Macs and I Pads.

3. Share your experience on this board.

If this conditions are acceptable I will get you a login.


Thanks for playing,

ACBD
I was involved in the last review of manual J.
The most disappointing short fall was the lack of identifying the sensible/latent loads at the cool damp conditions of rainy days and evenings.
The difficulty of low/no sensible with high latent loads which are so difficult to provide adequate fresh air air change while maintaining 50%RH with occupants in the home.
The basic info is there but not calculated. I raised the issue but the majors did not want to deal with the issue.
In most green grass climates, we have thousands of hours of 2,000-6,000 btus of latent load without any sensible cooling load.
Does the new calculators deal with this issue?
Regards TB

[AC Bad Dog]

I was involved in the last review of manual J.
The most disappointing short fall was the lack of identifying the sensible/latent loads at the cool damp conditions of rainy days and evenings.
The difficulty of low/no sensible with high latent loads which are so difficult to provide adequate fresh air air change while maintaining 50%RH with occupants in the home.
The basic info is there but not calculated. I raised the issue but the majors did not want to deal with the issue.
In most green grass climates, we have thousands of hours of 2,000-6,000 btus of latent load without any sensible cooling load.
Does the new calculators deal with this issue?
Regards TB

Mr Bear,

I would love to have your input on our new toy. If you would like a login we will get you one. Rules above apply. Your office cannot be within 150 miles of 100 Love Rd. Reading PA and you need to give us your feedback and help us build better mousetraps.

Also,I used your name in a poem I wrote for another thread, so I will re-post it here for you.I hope you receive this work in the spirt I intended:).

Thank You,

ACBD

ODE TO MANUAL J

I went to work one mourning, feeling just fine.
Gotta a call from a lady, about a quarter to nine.

She said my “AC’s broke, please come right away,
And don’t forget to bring Manual J”

Now I’m confused, as you can imagine why,
Why did she want me to bring, a Mexican Guy?

I jumped in my truck, and drove to her road,
Thinking I’ll get to her house, and just run a load.

When I got to her home it was easy to see,
There were five other trucks there, including Me!

There was a guy in the front yard, slinging his psychrometer.
I could not get close enough to get his name, so I didn’t bother.

Another guy in her den figuring infiltration rates by throwing blades of grass in the air,
Said he knew everything, had done that and beenthere.

I went down in the basement, cool and damp it was there,
In the corner doing RH calcs, I swear was a Bear.

I went back upstairs, and no I'm not kiddin,
There was Udarrell in the kitchen, preaching communist religion.

He said,“get your kids to help pay for your system before its to late,
Our business depends on un-funded federal mandates!”

Just when I thought, “I can’t see any more”,
Tedkidd showed up and set up his blower door!

When all these guys were finished, and had finally gone away,
I stuck around to see what the nice lady would say.

She was very impressed with all the song and dance,
But wondered if this was their first 1800 square foot ranch!

She said look-ee here Dog, this is all quite nice,
But I am still going to go with the guy who has the lowest price!

[ga-hvac-tech]

Mr Bear,

I would love to have your input on our new toy. If you would like a login we will get you one. Rules above apply. Your office cannot be within 150 miles of 100 Love Rd. Reading PA and you need to give us your feedback and help us build better mousetraps.

Also,I used your name in a poem I wrote for another thread, so I will re-post it here for you.I hope you receive this work in the spirt I intended:).

Thank You,

ACBD

ODE TO MANUAL J

I went to work one mourning, feeling just fine.
Gotta a call from a lady, about a quarter to nine.

She said my “AC’s broke, please come right away,
And don’t forget to bring Manual J”

Now I’m confused, as you can imagine why,
Why did she want me to bring, a Mexican Guy?

I jumped in my truck, and drove to her road,
Thinking I’ll get to her house, and just run a load.

When I got to her home it was easy to see,
There were five other trucks there, including Me!

There was a guy in the front yard, slinging his psychrometer.
I could not get close enough to get his name, so I didn’t bother.

Another guy in her den figuring infiltration rates by throwing blades of grass in the air,
Said he knew everything, had done that and beenthere.

I went down in the basement, cool and damp it was there,
In the corner doing RH calcs, I swear was a Bear.

I went back upstairs, and no I'm not kiddin,
There was Udarrell in the kitchen, preaching communist religion.

He said,“get your kids to help pay for your system before its to late,
Our business depends on un-funded federal mandates!”

Just when I thought, “I can’t see any more”,
Tedkidd showed up and set up his blower door!

When all these guys were finished, and had finally gone away,
I stuck around to see what the nice lady would say.

She was very impressed with all the song and dance,
But wondered if this was their first 1800 square foot ranch!

She said look-ee here Dog, this is all quite nice,
But I am still going to go with the guy who has the lowest price!

This is something to remember.

[just_opinion]

Mr Opinion,

You are the only one from this site to take us up on our offer to join the user driven software club.
We are now at 300 companies(mostly larger dealers, lots of GEo guys) who will be testing and helping develop a new generation of Home Audit Software. It also does a before and after Manual J.

Conditions:

1.Contactualy, We can't allow any company with an address within 150 miles of 100 Love RD Reading PA to use this software. This is the corporate office of the Utility that funded the project. As stated this tool creates a significant competitive advantage.

2. There are 70,000 lines of code and heavy graphics.You will need to upgrade your browser to the latest version. Or better yet use FireFox. We run great and Macs and I Pads.

3. Share your experience on this board.

If this conditions are acceptable I will get you a login.


Thanks for playing,

ACBD

Check my profile and send me an email.

Thanks for replying

[AC Bad Dog]

This is something to remember.

Thank You GA. Glad you liked the poem.

ACBD

[ga-hvac-tech]

Thank You GA. Glad you liked the poem.

ACBD

Not fussing, however I think you missed my point: The last two lines were highlited... the information in the last phrase is what I meant to bring attention to.

[^shane^]

My question is if she had 4 ton and the calculation showed she needs 3.5 Ton, can you just put a 2 stage 4 Ton in and then if she had a bit too much cooling the system will operate in stage 1 most of the time and stage 2 when she is having a party or on an unusually hot day?

I'm curious to know if there is a tonnage equivalence that shows a 4 Ton operating a stage 2 is 4Ton and at stage one is ? Ton (is it 2 ton, 2.5 ton, 3 ton, etc.).

I just read through 9 pages of in-fighting trying to find an answer to this question... Anyone? My home, based on 4 different contractors who all did calculations calls for a 3.5 ton single stage system. Will a 4 ton two stage system be dramatically over sized?

[ScorpionLeather]

I just read through 9 pages of in-fighting trying to find an answer to this question... Anyone? My home, based on 4 different contractors who all did calculations calls for a 3.5 ton single stage system. Will a 4 ton two stage system be dramatically over sized?

I had the same question before.. the expert advice I got was no.. it won't be dramatically oversized. It just wouldn't be as efficient as a 3 ton 2-stage (efficient, but a little undersized). Personally I would go with the 4 ton 2-stage!! When it's circulating the air in low stage, you will be able to set the t-stat higher and feel the same comfort as a single stage with a lower t-stat setting.

[beenthere]

I had the same question before.. the expert advice I got was no.. it won't be dramatically oversized. It just wouldn't be as efficient as a 3 ton 2-stage (efficient, but a little undersized). Personally I would go with the 4 ton 2-stage!! When it's circulating the air in low stage, you will be able to set the t-stat higher and feel the same comfort as a single stage with a lower t-stat setting.

Don't be so sure about that. A 2 stage 4 ton unit in first stage can have a capacity between 2.8 and 3.2 tons. So you can end up having to have the thermostat set just as high, and possibly higher then a single stage 3.5 ton. Plus, when it does go to second stage, you can have air noise from your registers, since most duct systems are under sized to begin with.

Most of the time. In order to use a larger 2 stage unit, some duct modification is need. Which can include adding additional supplies and or returns.

There are lots of threads on this board, about people having 2 stage units that are noisy in second stage, and they are unhappy with the noise.

[AC Bad Dog]

I just read through 9 pages of in-fighting trying to find an answer to this question... Anyone? My home, based on 4 different contractors who all did calculations calls for a 3.5 ton single stage system. Will a 4 ton two stage system be dramatically over sized?

Hey,

Since the Manual J oversizes by about 30% a 3 ton 2 speed might be just right. Remember, your AC has both a sensible(temperature) and latent(moisture) capacity. For all the talk around this subject you want to make sure your equipment selected has enough sensible (maybe 70-75% of the total) capacity. Various equipment combinations can change this ratio significantly upward.
Ask the folks who did these loads to show you the sensible load on your house and the sensible capacity of the equipment selected. Now have them rerun the loads at 78 degrees indoor temperature.

Small improvements in your home, Insulation, sealing, duct tightening, an awning to provide some shade at peak conditions, can easily reduce the load by 1/2 a ton and make your house considerably more comfortable as well.

By dehumidifying your house you can raise your indoor temp and feel as comfortable at 78 indoor as you were before with higher indoor RH. This change in your indoor design temperature will reduce your sensible load. So all your calcs done at 75 are now oversized even if they were correct before(and this is doubtful).

If you go 4 ton, have look at adding trunk, ducts, and a t stat. to create 2 zones.

If you post you street address and Zip, I'll run your house and email you a report including the Sensible Heat Ratio of your home.

Remember This, "bigger is worserer!

ACBD

[ga-hvac-tech]

The question I read is: Load is 3.5 tons.... should we install a 3 ton 2 stage, or a 4 ton 2 stage.

Well, have we discussed the WHOLE load? A few questions:

1) Are there kids in the house that will run in and out all summer (and leave doors open)?
2) Do the HO's entertain (cozen warm bodies ieasily an extra ton)?
3) Are there energy saving upgrades not yet done on the horizon (windows, insulation, etc)?
There are lots more questions BTW.

Bottom line: Call a PRO to come out and evaluate the WHOLE picture.

This idea of 'sound byte' answers to complicated questions, is, well, just dumb IMO.

This next thought should not be read as taking a cheap shot at anyone, rather something to think about:
When someone tries to sell me something... and tries to make it a simple decision while avoiding lots of details... I can see their ONLY goal is the sale... they could care less about my needs being met. I can guarantee folks I will not buy from someone that is only interested in the sale. IMO folks would be wise (and better consumers that get better value for their $$$), if they avoided salespersons, and found customer service folks.

[^shane^]

The question I read is: Load is 3.5 tons.... should we install a 3 ton 2 stage, or a 4 ton 2 stage.

Well, have we discussed the WHOLE load? A few questions:

1) Are there kids in the house that will run in and out all summer (and leave doors open)?
2) Do the HO's entertain (cozen warm bodies ieasily an extra ton)?
3) Are there energy saving upgrades not yet done on the horizon (windows, insulation, etc)?
There are lots more questions BTW.

Bottom line: Call a PRO to come out and evaluate the WHOLE picture.

This idea of 'sound byte' answers to complicated questions, is, well, just dumb IMO.

This next thought should not be read as taking a cheap shot at anyone, rather something to think about:
When someone tries to sell me something... and tries to make it a simple decision while avoiding lots of details... I can see their ONLY goal is the sale... they could care less about my needs being met. I can guarantee folks I will not buy from someone that is only interested in the sale. IMO folks would be wise (and better consumers that get better value for their $$$), if they avoided salespersons, and found customer service folks.

1) Are there kids in the house that will run in and out all summer (and leave doors open)?
Yes. Pool in the backyard. Dog, kids, and wife in and out all day during summer.
2) Do the HO's entertain (cozen warm bodies ieasily an extra ton)?
Yes.
3) Are there energy saving upgrades not yet done on the horizon (windows, insulation, etc)?
Need new windows, but those are WAY down the list.

Both of the contractors I am considering weren't putting on the "sell". The three that did put on the "sell" were immediately dismissed from consideration. The two I'm considering explained that the 4 ton two stage was a bit large for the house, but that the system would run a vast majority of the time on the low stage, thereby increasing the de-humidification activity of the system. The sixth guy didn't put on a "sell" but his prices were just way out of whack compared to the two I'm considering.




If you post you street address and Zip, I'll run your house and email you a report including the Sensible Heat Ratio of your home.

Remember This, "bigger is worserer!

ACBD

Thanks ACBD, but I really don't want to post my address on an open forum, and the private message system seems to be unavailable for this forum. I appreciate the offer though.

[ScorpionLeather]

Don't be so sure about that. A 2 stage 4 ton unit in first stage can have a capacity between 2.8 and 3.2 tons. So you can end up having to have the thermostat set just as high, and possibly higher then a single stage 3.5 ton. Plus, when it does go to second stage, you can have air noise from your registers, since most duct systems are under sized to begin with.

Most of the time. In order to use a larger 2 stage unit, some duct modification is need. Which can include adding additional supplies and or returns.

There are lots of threads on this board, about people having 2 stage units that are noisy in second stage, and they are unhappy with the noise.

Some 2 stage units simply reduce the speed of the compressor around 75%, but the high end models have 2 compressors so.. on those units wouldn't the first stage have 50% capacity or 2 tons in this case?

Is this to replace an existing system or are you having all new duct work installed? If it's all new duct work then maybe it can be designed to handle 4 ton correctly. Otherwise if it's swapping out an existing 3 ton unit then I agree with beenthere about the noise.

[^shane^]

Some 2 stage units simply reduce the speed of the compressor around 75%, but the high end models have 2 compressors so.. on those units wouldn't the first stage have 50% capacity or 2 tons in this case?

Is this to replace an existing system or are you having all new duct work installed? If it's all new duct work then maybe it can be designed to handle 4 ton correctly. Otherwise if it's swapping out an existing 3 ton unit then I agree with beenthere about the noise.

In all the years we have had the current system, the 3 ton unit never cooled the house satisfactorily even with an added foot of attic insulation - couldn't get below 78 degrees in the house unless outside temp was less than 90 degrees. We have adequate ducts for a 4 ton unit - duct work redone last year and upgraded. We do need additional returns added to the system and those are included in all quotes.

Looking at the Carrier Performance 17 two stage system (ARI#2628152) at a 4 ton size. For the last 4-5 years, we have had around 30 days a year over 100 degrees here and I want a system that will cool my house. I'm not looking for a "perfect" system - they don't exist. Too many variables. I know a 3 ton unit will not cool my house. Everyone giving what I deem honest estimates size the house at a 3.5 ton unit. Since two stage units do not come in half-ton increments, they bump up to a 4 ton.

[ScorpionLeather]

In all the years we have had the current system, the 3 ton unit never cooled the house satisfactorily even with an added foot of attic insulation - couldn't get below 78 degrees in the house unless outside temp was less than 90 degrees. We have adequate ducts for a 4 ton unit - duct work redone last year and upgraded. We do need additional returns added to the system and those are included in all quotes.

Looking at the Carrier Performance 17 two stage system (ARI#2628152) at a 4 ton size. For the last 4-5 years, we have had around 30 days a year over 100 degrees here and I want a system that will cool my house. I'm not looking for a "perfect" system - they don't exist. Too many variables. I know a 3 ton unit will not cool my house. Everyone giving what I deem honest estimates size the house at a 3.5 ton unit. Since two stage units do not come in half-ton increments, they bump up to a 4 ton.

Shane, based on everything you said, if I were you, I'd go with a 4 ton 2-stage unit for sure, no question about it in my mind. You said "I know a 3 ton unit will not cool my house"... "we have adequate ducts for a 4 ton unit.. redone last year." Just double check with the contractor that the ducts will handle 1600CFM ok. But even if, let's say for whatever reason the ducts were designed last year to only handle 3 tons, then I would personally add more supplies/returns just to be able to use a 4 ton 2-stage unit. And be sure to get a 2-stage that has 2 compressors that goes to 50% (2 tons) in low mode, not one of those that only bump it down to 75% on a single compressor.

The only exception I can think of to go with 3 ton would be if you have inadequate insulation (missing insulation in the attic etc) and plan to update that in the future, but I doubt that just replacing windows would make that much difference.

After I had a 2 stage installed last year, I will never go back to single stage. The difference in comfort is HUGE having that gentle breeze in low stage.

[beenthere]

In all the years we have had the current system, the 3 ton unit never cooled the house satisfactorily even with an added foot of attic insulation - couldn't get below 78 degrees in the house unless outside temp was less than 90 degrees. We have adequate ducts for a 4 ton unit - duct work redone last year and upgraded. We do need additional returns added to the system and those are included in all quotes.

Looking at the Carrier Performance 17 two stage system (ARI#2628152) at a 4 ton size. For the last 4-5 years, we have had around 30 days a year over 100 degrees here and I want a system that will cool my house. I'm not looking for a "perfect" system - they don't exist. Too many variables. I know a 3 ton unit will not cool my house. Everyone giving what I deem honest estimates size the house at a 3.5 ton unit. Since two stage units do not come in half-ton increments, they bump up to a 4 ton.

If your duct work has been resized that it is big enough for 4 rons. Then ask one of those contractors to do a static test on it. Since it would have to be operating at a .4" or lower when moving 1200 CFM to be near big enough to handle the 1600 CFMs a 4 ton would move.

[AC Bad Dog]

I just read through 9 pages of in-fighting trying to find an answer to this question... Anyone? My home, based on 4 different contractors who all did calculations calls for a 3.5 ton single stage system. Will a 4 ton two stage system be dramatically over sized?

Hi,

You can get a 3.5 ton 2 Stage unit.

I have little confidence in you four contractors "loads", however, if you do, then Rheem makes a 3.5 ton two Stage. RASL-039.

Remember, these loads are estimating a condition that will occur about 2% of the time. Also recall when you remove the moisture from your house you will feel comfortable at higher indoor temps.

A 4 ton will be about 2.8 tons on first stage and short cycle at part load conditions below that. You could be below that point about 90% of the time.

ACBD

[beenthere]

Its not a 3.5 ton, falls short by a few thousand BTUs. Closer to a 3.25 ton unit.

[AC Bad Dog]

1) Are there kids in the house that will run in and out all summer (and leave doors open)?
Yes. Pool in the backyard. Dog, kids, and wife in and out all day during summer.
2) Do the HO's entertain (cozen warm bodies ieasily an extra ton)?
Yes.
3) Are there energy saving upgrades not yet done on the horizon (windows, insulation, etc)?
Need new windows, but those are WAY down the list.

Both of the contractors I am considering weren't putting on the "sell". The three that did put on the "sell" were immediately dismissed from consideration. The two I'm considering explained that the 4 ton two stage was a bit large for the house, but that the system would run a vast majority of the time on the low stage, thereby increasing the de-humidification activity of the system. The sixth guy didn't put on a "sell" but his prices were just way out of whack compared to the two I'm considering.



Thanks ACBD, but I really don't want to post my address on an open forum, and the private message system seems to be unavailable for this forum. I appreciate the offer though.

Hey,

The most likely reason the guys all came up with 3.5 tons is you told them your 3 ton could not keep up on extreme days. Very easy for them to game the loads and give you what you want. That's what sales folks do. If you really think you need 3.5 ton the RASL will get you to within 95% of that and you will not have to worry about being way over on 2nd stage.

RASL-039JEC RCFN-H*3624 RGTM-07(E,N)RBGS 40000BTUH 18.00 13.25 AHRI #3763831 or AHRI #3259817 Cooling only

It is also likely this unit has as much or more sensible capacity than the 3.5 ton units proposed.

Since everyone told you 4 ton was to big, this looks like the unit for you.

ACBD











The RASL 039 Can get to 40,000 BTU's Cooling.

[AC Bad Dog]

Its not a 3.5 ton, falls short by a few thousand BTUs. Closer to a 3.25 ton unit.

Hey,

FYI, the 1st thing they teach us at Manual J university is how to back into the numbers we want. The most efficient way to do this is by adding outside air to our manual J spreadsheet.

If the RASL-039 is 40,000 BTU's/hr or about 3.34 Tons and you have stated repeatedly you need a 3.5 ton, well how much is this difference?

It is less load than your bathroom fan running, or about the same as two people dancing, or making love.

So don't do these things if it is over 95 degrees outside!

ACBD

[tedkidd]

Hmmm. Contractors telling you 4 tons is OVERsized!

House not ever getting near set point.

People in and out, possibly leaving doors open.

Sounds like operator error. Maybe I missed it, but if we drill down what is the problem you want solved? If you are trying to keep them comfortable, correct the ignorant behavior instead of installing oversized equipment.

If it's your comfort, that might mean a different approach.

If it were me, I'd install zoning to control comfort where I wanted, and if they want comfort tell them to stop cooling the outdoors.

[ScorpionLeather]

Hmmm. Contractors telling you 4 tons is OVERsized!

I think Shane's question was whether 4 ton would be dramatically oversized. If the contractor's Man J calculations wind up at 3.5 tons for a single stage.. then no, I don't think a 4 ton 2-stage would be dramatically oversized. In fact it's probably ideal in this case where the room cooling temp won't even make it to the t-stat setting with the existing 3 ton.