sizing the unit

fhammette · 11-12-2007, 09:07 PM

I have received two quotes to upgrade my units and change the ducks. They sound expensive, but if they do the job I may proceed. (About $16,000). My problem is one installer said I need a 3 1/2 ton unit for cooling, and a carrier MV BO80 80,000 BTU 96% efficiency heater. The other guy said I must have a 4 ton Trane Air unit and a 120,000 Tran BTU heater (95% efficiency) . Both would be a zone unit, one is two zone the other is three zone. The house is only two stories, and is only 2000 square ft. The windows and house are well insullated and I have skylights upstairs.

I live in the Atlanta Ga. area.

This is a big difference, expecially in the heater IE: 80,000 or 120,000 BTU.

whose wrong? whose right?

any help is appreciated.

Lee

undone · 11-12-2007, 11:20 PM

Quote:

Originally Posted by fhammette

I have received two quotes to upgrade my units and change the ducks. They sound expensive, but if they do the job I may proceed. (About $16,000). My problem is one installer said I need a 3 1/2 ton unit for cooling, and a carrier MV BO80 80,000 BTU 96% efficiency heater. The other guy said I must have a 4 ton Trane Air unit and a 120,000 Tran BTU heater (95% efficiency) . Both would be a zone unit, one is two zone the other is three zone. The house is only two stories, and is only 2000 square ft. The windows and house are well insullated and I have skylights upstairs.

I live in the Atlanta Ga. area.

This is a big difference, expecially in the heater IE: 80,000 or 120,000 BTU.

whose wrong? whose right?

any help is appreciated.

Lee

I didn't know system pricing was so high in the east. I'm moving!
Ask your estimators to provide a 'load calculation'. If niether can, find one who will. I worked for someone that deliberately oversized the equipment so he could charge more--maybe the case, maybe not. The cooling difference isn't that bad--a half ton? But the heating seems pretty extreme.

moneymgmt · 11-14-2007, 11:31 AM

Not to go on a tangent, but what exactly are you having done? That pricing seems extreme for such basic units. You're in GA, so personally, I'd go the 80k btu route. Now if you were here in Michigan with an unisulated house like mine, different story all together. I just had a 70kbtu 95% unit and 2 ton A/C installed with new duct work for about 1/4 of that. Now granted, the ducts were very simple bc you have complete access from the unfinished upstairs, but wow. But if you've got the money and dont care, its not going to hurt me either.

metal-maniac · 11-14-2007, 03:51 PM

I am a contractor in the northern Atlanta area and the 3.5ton with 80,000 is about right. 120,000 is way overkill , as far as the 3.5 vs. 4 ton would be a factor depending on the house. Price is high but this also has to be taken into consideration of the install. I Would try another contractor or 2!

fhammette · 11-15-2007, 08:11 AM

good advise from all, which I will follow. I will have a load calculation done, and also get another quote or two to be sure the price is reasonable. Thanks to you all.

VAheatcool · 11-16-2007, 10:24 AM

I agree with everyone about load calculation first. Price is NOT too high for all new ductwork, make them show you how they will size and seal it. 80,000 is a large furnace for VA never mind GA! Dual fuel is the ONLY way to fly in our part of the country(unless you go geo....) its usually only 1000 to 1500 more and will save you about 2/3 of your gas bill...