How important is central location of furnace?

[mxjamie540]

As you may remember, getting several bids on replacement hvac systems. I live in a one story ranch. The existing furnace sits in the attached 2 car garage. So the supply plenum has to run all the way to the other end of the house (70 feet or so) with the various room supplys venturing out another 15-25 feet.

Wondering if putting the furnace in the attic and thereby getting a more centralized location would be of a great benefit. Or is the new variable and multi speed blower systems adequate to push air as far as I need it to and at the proper velocity?

I have had 4 HVAC contractor's out and only 1 has proposed the idea of the furnace in the attic. I feel that this would obviously help to balance the system. Am I wrong in this logic?

[hvacvegas]

Technically, your logic is correct. The more centralized the furnace, the better.

Except that your doing a change out, not building a new home. The cost of relocating vs better balance isn't equal. It's not worth the money. A better investment would be correct duct sizing, and additional insulation.

Plus, since the unit is going to be located in the attic, your going to have a problem with water damage. All systems break. Eventually, the air conditioning coil is going to have a water leak. Might not be this system, could be the next system, who knows. Their are options, such as a secondary drain pan, but you still have the possibility of water damage to your ceiling.

I'd say,

[cuchulain]

If the contractor does all his homework and knows HOW to set up ductwork and offer you the correct equipment for your situation then location of the furnace isn't a major problem. We have an infinity system that we installed after hurricane IKE 2 years ago that I had to fabricate duct work for under the house. The HO did NOT want to have anything changed from her original setup even though a few things in the house were changing and codes/install practices had changed dramitically. The furnace sat on the east side of the house roughly in the middle, the main trunkline came down and ran in a very long horse shoe shape roughly 50' without counting radius' with multiple taps comming off some measuring an additional 30'. Because of how I did the reductions and with the particular furnace we have no trouble with airflow in the house

[mxjamie540]

There seems to be debate amongst my bids on what the correct thing is for the ductwork.

One wants to run new R8 flex in attic

one wants to decrease supply plenum size in increments on the last 15-20 feet to boost velocity

one never mentioned ductwork at all

one says the newer super awesome blower would more than likely effectively remedy the "cold rooms vs. some hot rooms" syndrome I seem to battle. He feels to try new system first, then if still not adequate, start troubleshooting ductwork, but seems confident it is mostly a old slow blower issue.

R38 or a little more in attic, new windows, 2 of the 4 doors are new units, standard r13 in walls, no crawlspace insulation. Approx 1800 sq ft with new addition of 160 sq ft going on, Southern Illinois climate.

[cuchulain]

one says the newer super awesome blower would more than likely effectively remedy the "cold rooms vs. some hot rooms" syndrome I seem to battle. He feels to try new system first, then if still not adequate, start troubleshooting ductwork, but seems confident it is mostly a old slow blower issue.



Remember one important factor. Air takes the path of least resistance. So if your already battling hot/cold rooms then a new blower won't necessarily fix the problem if the ductwork isn't examined.

[mizzouhvac]

If your duct is sized properly your system can be balanced to provide even air distribution throughout your house. No matter where the air handler is located.

[mxjamie540]

Alrighty..... thanks guys

[hvacvegas]

There seems to be debate amongst my bids on what the correct thing is for the ductwork.

One wants to run new R8 flex in attic
Sounds good. More insulation on the branch runs, means less conditioning lost to the attic. Ought to check the wrap of the duct also. Probably internally insulated, yes? If so, nothing wrong with wrapping more on top. That, or you probably have a ductboard (rigid fiberglass) duct system, which if sizing is correct, I would leave alone.

one says the newer super awesome blower would more than likely effectively remedy the "cold rooms vs. some hot rooms" syndrome I seem to battle. He feels to try new system first, then if still not adequate, start troubleshooting ductwork, but seems confident it is mostly a old slow blower issue.
I've seen those blowers cause more PROBLEMS than solutions. Although it MAY balance the house more, and use 70% less electric to operate in a correctly designed system, one possible result the indoor unit being louder, and increased noise through the registers.

R38 or a little more in attic, new windows, 2 of the 4 doors are new units, standard r13 in walls, no crawlspace insulation. Approx 1800 sq ft with new addition of 160 sq ft going on, Southern Illinois climate.Wait, what? Your duct is in the attic, and not the crawlspace? Do you have any water lines in the crawl space? How "tight" is your crawlspace? Vapor barrier, foam board on the block...?


.

[tedkidd]

What havc said.

Oversize the new equipment relative to your ductwork and the super mazadoobie (ECM) blower will ramp up attempting to deliver 2 gallons of milk (airflow) through your 1 gallon ductwork. Ecm will work overhard, save little, and die early.

Everything is connected and requires a balance. One link in chain out of balance and unhappiness results.

What size furnace did you have, and what size is recommended?

[mxjamie540]

no no...... current supply ducts are in crawlspace, return is in attic, sorry if I confused.


current system is a Amana.... I think it is a 3 ton condensor and a Ruud furnace, I think the model was umc 125 or something like that, so I assume it is a 125k unit,

recommendations have been 80k furnace and 3 ton unit, to a 100k furnace and 4 ton unit. Waiting still on the latest contractor's numbers.

Crawlspace has vapor barrier but that is it..... no actual insulation in crawlspace.

[tedkidd]

Where are you, house size, age, annual energy use?

Crawlspace vented to outdoors?

Current furnace or ac ever run nonstop?

[mxjamie540]

house built in 1972, vented crawlspace, usual utility bill (gas & electric combined) $200-250, with peaks of over 300 in January, Feb, July, Aug. Have had bills close to 400 before.

A/C runs non-stop after about noon if temp is over 90 degrees
Furnace only runs for 10-15 minutes, maybe less.

[darctangent]

house built in 1972, vented crawlspace, usual utility bill (gas & electric combined) $200-250, with peaks of over 300 in January, Feb, July, Aug. Have had bills close to 400 before.

A/C runs non-stop after about noon if temp is over 90 degrees
Furnace only runs for 10-15 minutes, maybe less.

I would be very motivated to test that return for air leaks and too see where the insulation could be improved. The attic is likely to be a large energy loss with the return air passing through it- typical much more so than the crawlspace, IMO but it all really depends on the situation.

Did anybody commit to a Heat load Calculation, or are they guessing at the equipment size?

Did anybody do anything, or promise to do anything concerning testing the ductwork in any way, shape or form?

Modification without information is spending money without a plan. Insulating ducts is always good, but if you install flex where you had hardpipe you could likely reduce airflow through the system and that's generally very bad.

I don't really have a huge problem with doing work in phases to address problems as long as it's with an overall plan. mapping out possible improvements and combining work in a sensible fashion should work well for you and could save you money. But you need to make improvements by identifying your weak points. Key areas to look at are the HVAC equipment, The ductwork, and the "thermal envelope" of the home. any one of these components can have key deficiencies that can impact your comfort and cost real money. A mechanical contractor isn't necessarily going to be able to review your "thermal envelope" but they should be able to properly assess the equipment and ductwork, but not everybody will, not everybody will know how.

Choose your contractor very, very carfully.

The biggest choice you have to make is about the contractor, not the equipment.

[George2]

There seems to be debate amongst my bids on what the correct thing is for the ductwork.

One wants to run new R8 flex in attic

one wants to decrease supply plenum size in increments on the last 15-20 feet to boost velocity

one never mentioned ductwork at all

one says the newer super awesome blower would more than likely effectively remedy the "cold rooms vs. some hot rooms" syndrome I seem to battle. He feels to try new system first, then if still not adequate, start troubleshooting ductwork, but seems confident it is mostly a old slow blower issue.

R38 or a little more in attic, new windows, 2 of the 4 doors are new units, standard r13 in walls, no crawlspace insulation. Approx 1800 sq ft with new addition of 160 sq ft going on, Southern Illinois climate.

I love the contractor that said, " The new (super awesome) blower will "probably" fix the problem".

I worked with a salesman who knew NOTHING about airflow, ductwork sizing, HVAC, etc. (and didn't want to learn). That was (one of) his favorite line(s).

When I pointed this out to the boss, he told me, "What the homeowner doesn't know, won't hurt them".

[mxjamie540]

I am fully aware about the equipment vs. contractor issue. That is why I have been asking so many questions. I have frequented this site for about 5 years off and on.

I really don't care what equipment I end up with, as long as it works as designed and to it's full potential. Heck, I may not need any ductwork work done...... my system is pathetically old and probably weak.

I have had 2 out of 4 HVAC guys do manual J's. I have only gotten the results from one (the other just came out Friday and has not completed the bid yet). One of them is the guy who thinks that the new system and blower will help to cure my problems.

The one manual J that has been completed stated I needed about 29,000 btu and hour heat/cool (going by memory here, I was not actually given a copy)..... does this sound about right?

Nobody has actually tested the ductwork or ran pressure calcs on it. Everyone is going by appearance and dimensions I suppose.

To answer the return air question, it is in the attic and currently insulated with fiberglass batts...... albeit the batts could use a little "touching up"

So...... any of you guys who OBVIOUSLY know what you are doing willing to come to Southern Illinois and install my system? Hey.... I got a cool flatscreen.... I don't drink, but I definitely can BUY!

[hvacvegas]

Glad to hear you've had manual J's done. Thats usually a sign of a high class contractor, and it gets them big points.

You'd be surpised how warm your crawl space can be by throwing plastic on the ground, putting foam board on the block, covering vents, and getting a sealed access cover. Now you can close off that vent thats blowing into the crawl, preventing your pipes from freezing. Problem is, you can't go one way or the other, you have to decide on a sealed or vented crawl.

I just did a house with a system extremely close to what your talking about. Same setup.

We wrapped all the duct in insulation (while hanging in the crawl). Took the branch pipes apart and used flex duct, over top of the metal (easy to do, and you get the benefit of insulation and metal pipe.)
GC did what I mentioned about the crawl.

Homeowner is one happy camper.

[tedkidd]

house built in 1972, vented crawlspace, usual utility bill (gas & electric combined) $200-250, with peaks of over 300 in January, Feb, July, Aug. Have had bills close to 400 before.

A/C runs non-stop after about noon if temp is over 90 degrees
Furnace only runs for 10-15 minutes, maybe less.


Ok, I'll guess, 1800 sf? Please confirm & report annual kwh and therm consumption?

[darctangent]

I am fully aware about the equipment vs. contractor issue. That is why I have been asking so many questions. I have frequented this site for about 5 years off and on.

I really don't care what equipment I end up with, as long as it works as designed and to it's full potential. Heck, I may not need any ductwork work done...... my system is pathetically old and probably weak.

I have had 2 out of 4 HVAC guys do manual J's. I have only gotten the results from one (the other just came out Friday and has not completed the bid yet). One of them is the guy who thinks that the new system and blower will help to cure my problems.

The one manual J that has been completed stated I needed about 29,000 btu and hour heat/cool (going by memory here, I was not actually given a copy)..... does this sound about right?

Nobody has actually tested the ductwork or ran pressure calcs on it. Everyone is going by appearance and dimensions I suppose.

To answer the return air question, it is in the attic and currently insulated with fiberglass batts...... albeit the batts could use a little "touching up"

So...... any of you guys who OBVIOUSLY know what you are doing willing to come to Southern Illinois and install my system? Hey.... I got a cool flatscreen.... I don't drink, but I definitely can BUY!

Well first- It's hard a guess at a value for your load without knowing more than I do. but 29K isn't a crazy number for cooling, I'll tell you that. Your heating BTU's will be higher.

Where the ducts are concerned I would call up each contractor and ask them some questions, and it's better if you don't try to act like you know what you are talking about, but rather just say, hey, I don't know if this is true or not but, "what does this mean?"

1) What is static pressure? - just ask like you had heard it from another contractor, or off the internet. Static pressure is a measurement or resistance to airflow in the duct system. If it is too high, your system is restrictive to the flow of air. keep in mind that the measurement is relative to the volume of air that is needed to move through the system. If we determine that the new system doesn't need as much airflow as the old one we get an automatic reduction in static pressure. If the contractor says that he's never heard of that, or that stuff is BS, quickly escort him to the door, thank you very much.

2) How would/could you test the ducts? There are many ways to go about this, some sophisticated, some not, but the answer will tell you alot about the contractor. we can measure resistance to flow (static pressure) we can measure volume of air (CFMs) we can measure leakage (with a duct blaster, the most expensive method) we also assess visually. One thing that I do is to locate sections of ductwork that are particularly restrictive to the flow of air and figure out how they can be improved. We can also test how much air comes out of what registers in the house. Finally we can look for week spots in the insulation on your duct work if you have any. Insulating and air sealing the ducts in your attic could be very beneficial. Are the ducts in you attic insulated by themselves?

As to finding a contractor I might offer this- One, you might post a new thread with your location and see who responds. I realize you might have your reasons for maintaining a level of anonymity in the forum, but there are people here from all over the country. A contractor that has spent some quality time on HVAC-talk would not be a bad place to start. There is one other thing I can look into. We have social groups organized by state, I could look there to see who might be close.

[darctangent]

Ok, I checked.

Nothing going on in Illinois for a list. The powers that be are suposed to be building that into the site, but that's sometime into the future.

I would post a new thread if your current list of contractors turn out to be duds.

JMO.

:.02:

[mxjamie540]

R38 or a little more in attic, new windows, 2 of the 4 doors are new units, standard r13 in walls, no crawlspace insulation. Approx 1800 sq ft with new addition of 160 sq ft going on, Southern Illinois climate.

Current supply is in crawlspace, uninsulated. Return is in attic.... insulated

1800 sq ft now..... with an addition of 160 sq foot going on this spring/summer (laundry room/closet)

[genduct]

Convert your crawl space to a mini basement. I would like to believe this is already the case since you said supply duct in crawl is NOT INSULATED, But I know better than to assume that.
Replace the supply and return duct in the crawl and insulated it.
It will cost more but you'll get a good job that will save you $$$$$

[genduct]

Bite the bullet!!!!
Convert your crawl space to a mini basement. I would like to believe this is already the case since you said supply duct in crawl is NOT INSULATED, But I know better than to assume that.
Replace the supply and return duct in the crawl and insulated it.
It will cost more but you'll get a good job that will save you $$$$$

[mxjamie540]

Electrical usage is right about 20,000 kwh a year with peaks of 2,500 per month in July & August. This also is with us being away from the home for a full 7 days out of the year.

Gas is about 357 therms, however this number only shows 2 months when we DID NOT heat with wood. I cannot access bills earlier than this timeframe online.

The two months that had our house using NG as heat and not wood we had
134 therms and 155 therms respectively. So obviously, if I did not heat with wood my therm usage would be MUCH higher.

While heating with wood in the winter, my average monthly therm usage is 10-15 therms.

copy of a bill so you can see rates.

Total Therm 4TC10560 01/03-02/03 31 5262.0000 5281.0000 19.0000 1.0000 1.00000 19.0000E
Total kWh 2SC01775 01/03-02/03 31 66457.0000 67767.0000 1310.0000 1.0000 1310.0000E
Service To SUMMARY Service To
Sales Therm 02/03/2011 19.0000 Total kWh 02/03/2011 1310.0000
Non-Summer kWh 02/03/2011 1310.0000
NATURAL GAS SERVICE BILLING DETAIL - Rate Zone III
GDS-1 Residential Gas Delivery-Space Heat Service From 01/03/2011 to 02/03/2011
Customer Charge $20.43
Delivery Charge Gas 19.00 @ $.07589000 $1.44
Res Gas Env Chg 19.00 @ $.02009120 $0.38
Rider GER Charge 19.00 @ $.00781128 $0.15
Total Delivery Service Amount $22.40
Gas Supply Service From 01/03/2011 to 02/03/2011
Gas Charge (PGA) 19.00 @ $.59964582 $11.40
Total Supply Amount $11.40
Taxes Service From 01/03/2011 to 02/03/2011
Illinois State Gas Revenue Tax $0.46
Illinois State Commerce Commission Tax $0.03
Total Tax Related Charges $0.49
Total Natural Gas Charges $34.29
ELECTRIC SERVICE BILLING DETAIL - Rate Zone III
DS - Residential (DS-1) Service From 01/03/2011 to 02/03/2011
Former Space Ht Acct 15k And Over
Customer Charge $12.99
Meter Charge $4.72
Distribution Deliv Chg Non-Summer 800.00 kWh @ $.02403000 $19.22
Distribution Deliv Chg Non-Summer 510.00 kWh @ $.01681000 $8.57
Electric Environmental Adj 1,310.00 kWh @ $.00191280 $2.51
Rider EDR Charge 1,310.00 kWh @ $.00169072 $2.21
Total Delivery Service Amount $50.22
Electric Supply (BGS-1) Service From 01/03/2011 to 02/03/2011
Purch Elec Non-Summer(0-800 kWh) 800.00 kWh @ $.05619000 $44.95
Purch Elec Non-Summer(> 800 kWh) 510.00 kWh @ $.01844000 $9.40
Purchased Electric Adj 1,310.00 kWh @ $.00181740 $2.38
Rider PER Supply Cost Adj 1,310.00 kWh @ $.00128000 $1.67
Transmission Service Charge 1,310.00 kWh @ $.00435000 $5.70
Total Supply Amount $64.10
Taxes Service From 01/03/2011 to 02/03/2011
Illinois State Electricity Excise Tax $4.32
Electric Distribution Tax $2.58
Total Tax Related Charges $6.9

[tedkidd]

Crap, wood makes it tough. How many cord?

That electric use is huge, and the unskewed gas months appear to be also. I'd guess you have few occupants or heat water with electric as non heat gas use is pretty low.

How do you distribute your heat? Do you have hot tub, pool, grow dope (kidding) or some other obvious high electric consumption devices?

Clearly significant opportunity will be uncovered by a quality energy audit given the data you've shared.

[mxjamie540]

2 adults, 2 children under 10. Gas furnace and water heater. Everything else is electric. No hot tubs or anything, but did have an above ground pool (gone now).

All these figures are also before the cellulose which was just blown in about 3 weeks ago. I hope to see a difference this summer even if no HVAC equipment were to be changed.

I have found an energy audit company close, will call tomorrow...... wondering how much something like that costs (don't worry, I am not asking for actual answers on price)

Use between 3-4 full cords a year..........but I can be at 78 degrees inside if I want, not the 68 the thermostat is set for because of high utility bills. Wife is much happier in the winter with the stove, which makes me happy!

All the HVAC talk began because Summer is approaching and that is the season when we are uncomfortable in the house. I honestly would be OK with not replacing the furnace..... but I am going to anyway to have a matched efficient system for the summer months. I do not use the furnace in the winter.

In regards to cooling.... I forgot to mention that my family room was once a one-car garage and has a bay window...... the window is all new (low-e, argon, double pane) however, I have to keep a window a/c unit in that room or it is unbearably warm.

I think I may have fixed this a little for this summer by adding the insulation and by sealing the access from the garage attic to the main attic. My thought was that hot air from my 2 car garage was getting pulled into the main attic and thereby heating up my family room...... also the solar gain from the bay window is a problem.... .we use black out drapes on this window in the summer.

What is the average single family home electric usage per month?

[tedkidd]

Glad you are getting audit. Blower door test will tell a lot, please post that number.

Did air sealing precede cellulose? Or simply "blow n go"? Most dont realize stack & mechanically induced Air leakage from house to attic in heating season, and from attic to house in cooling season, is equally if not more responsible for comfort and energy problems as insufficient insulation. Porous insulation stops air leakage as well as a colander holds water.

I suspect fixing duct leakage and insulation should cause your current ac to be oversized. Although insulation will help, short cycling likely to occur. Possibly running blower fan continuously will band aid imbalance.

Modulating furnace, hybrid heat and air sealing will mean heating cost should be less than the cost of wood. $1 worth of gas has more btu when very efficient delivery can occur.

Under 1000 monthly kwh is what I typically see in situations like yours.

[mxjamie540]

I did quite a bit of battle on the air infiltration front. I spent seval hours in attic sealing any hole I could access. sealed all the electrical boxes in the perimeter walls. Laid on my back for several hours sealing holes in floor and rim of crawlspace (more to do on that still).

If current ductwork stays, I will def mastic and UL 181 the joints.

Not really looking to give up on teh wood.... as I don't purchase it, plus I enjoy the cutting/splitting/stacking..... makes me feel more like a man that I and activily doing something to provide comfort and safety for my family ( I know..... lame right! lol)

Seriously guys...... I know I have asked way too many questions, but THANK YOU ALL for putting up with me :) !

[hvacvegas]

Seriously guys...... I know I have asked way too many questions, but THANK YOU ALL for putting up with me :) !

actually, your the perfect member. Seriously. No DIY, no arguing with the pros, making intelligent responses. Perfect.

[mxjamie540]

Uhh.... WOW..... I mean a sincere thanks!



I know from my lurkings on here that you guys can be a bit harsh (with good reason) to some newbs..... I know better than to talk out my butt and then get fed to the sharks. I know a little..... but obviously nothing like you guys.

I am a DIY guy at heart. Love forums and love saving money. Have done 98% of all my remodels/rebuilds myself.... which has also given me the knowledge that sometimes.... it is just easier, safer, and less frustrating (ie: save marriage...lol) to let the pro's deal with the headache and do it right.

Now.... when it comes to making big trees fit into a little stove.... I'm your man for advice!

[aircooled53]

Air- that which remove latent heat and humidity from condition space..Which if you increase the ductwork size to the load, then air changes per hour will remove more heat..

Increase insulation in attic space ..Get a Carrier V/drv furnace and good 14.0 condenser and filter system , lower energy 40%..