New construction quote- Bryant Evolution

16 years ago

We are building a new home in central GA. About 6600 Sq ft. in 2 levels and a walk out basement. Our builder is using a HVAC contractor that did a Manual J/D Calc. He is using Bryant Evolution 16 SEER for all three HP units. Evolution are only sold in full ton.

For the main floor, the manual J recommends a 3.4 ton. He is putting a 4 ton with 2 returns for $11,500.

For the 2nd floor, Manual J recommends 3.6 tons. He is putting 4 tons with 5 returns (each BR) for %12,500.

For the basement, manual J recommends 2.7 tons. He is putting a 3 ton with one return for $10,700.

Total is $34,700 including all ductwork and t-stat.

The duct work for the main floor and basement will be in the basement. It will be R8 flex duct. The duct work for the 2nd floor will be in the attic which is unvented.

Our insulation is R30 open cell foam in roof rafters, sealed. The walls will be R13 fiberglass batts with everything caulked for a tight seal. Between floors will be fiberglass batts-R19. The house will be an energy star home with a final blower test to be done. Our house has plenty of windows with an average U-value of 0.29, SHGC of 0.20 and is facing south-southwest. Electricity is %0.085/KWh.

Please advise me if this is a reasonable quote and if you recommend any changes to our HVAC plan. Thanks in advance.

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Comments (6)

tigerdunes
16 years ago
sajakh

11 tons of cooling for a new home with what I assume is excellent new home construction/insulation qualities? I would review builder/dealer's calculations very closely. oversized systems are never a good idea.

I would want to see complete list of mdl numbers of equipment to be provided for each floor/system. what size heat strips?

one suggestion is to use zoning controls for the main floor and basement and just purchase one system.

IMO
neohioheatpump
16 years ago
Your main floor sounds like it should be 3-tons. Keep in mind you have seperate heat/cool zones above and below and will be very easy to maintain temperature.

Basements don't require much heating and cooling. I would recommend only 2 tons. Even if its a walkout I"m sure not all the walls in the basement are exposed.

I would continue to stick with 4 tons on 2nd floor. That will need the most heating/cooling.

Good choice with going with heatpumps. With your climate and those electric prices you will have inexpensive heating and cooling.

With 4 tons up, 3 tons middle, and 2 tons down, you will have 9-tons of heating/cooling for 6600. Considering the nature of your house that sounds like plenty. Its not good being oversized.

You have good insulation in the walls and attic. You have an energy efficient home.
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sajakh
Original Author
16 years ago
Thanks alot for your opinion and time.

Tigerdunes, he has not yet given us a detailed rundown of the model #s but will most certainly get it before we finalize the work. We opted not to get the heat strips. We will have a non vented gas burning fireplace on the main floor. Our current house doesn't have heat strips and we don't miss it too often. If we really need it, we have some electric space heaters.

I agree with your suggestion about zoning but I'm not sure the contractor is experienced in zoning. Honestly, I don't know.

I purchased the HVAC calc this weekend and spent half my Sat PM inputting all the data.

Results: BTU/h
Whole house: Cooling- 70391 (5.9 tons); Heating- 75054 (6.3)

Basement: Cooling-8469 (Main floor: Cooling-34041 (2.8); Heating-30918 (2.5)
2nd Floor: Cooling-27873 (2.3); Heating-28120 (2.3)

Neohio, We have a large tall attic that us unvented so you're right, a 4 ton in the upper may be better.
tigerdunes
16 years ago
sajakh

I mean no disrespect but your decision on backup heat strip is a poor decision. I know Ga area/climate very well. Heat strips are needed for defrost, auxilliary, and emergency heat. I can't believe a reputable dealer would agree to this. Heat strip backup is relatively inexpensive and you would only be hurting yourself and system's functionality.

your load calcs raise alot of questions as far as sizing goes.

IMO
sajakh
Original Author
16 years ago
Tigerdunes,

No disrespect taken of course. I will ask him about the heat strips and whether they're included.

Do you think my calculations are off? My calculations do not include duct losses since all duct work will be in conditioned space. Also the HVAC contractor did not account for my installed low u factor (0.47 vs 0.29).
david_cary
16 years ago
My experience for comparison. 4000sq + walkout in NC. I'm sure we are a bit cooler. Carrier Infinity seer 16. 4 tons 1st floor, 3 tons 2nd floor. 11/10 ft ceilings down; 9 up. Energy star but unconditioned attic.

Zoned 2nd floor, NG as dual fuel on 1st floor. Basement not finished but doing 4 tons on 1st floor was for the basement also. $21k. So to me $34k sounds a bit high. Yes you have 3 systems but don't have zoning or dual fuel.

Living here for a year - basement has never needed much a/c. I can't believe their calc for the basement. We have a walkout with windows just on 1 wall (East). There are 10 windows that are 2.5x6 ft but 4 are covered by deck. I still have some insulating to do. I really suspect we need 1/2 ton down there (but I am going to zone off the 1st floor). The second floor needs little a/c - I know it is the # of windows.

I'm sure every house is different but we have much less windows upstairs. 3 west facing, 8 East but 3 of those are smaller. Down has 10 East and 6 West. For our house, that really lowers the a/c need. When the house is tight, there are very few heat gains other than windows and occupants/heat loads. I'm not sure if manual J captures that and it is just my opinion.

In the end, we could have 2 tons up and 3 tons down. This summer here was probably hotter than your average summer. We never had an issue with the system keeping up - not even close. I am pretty confident that you could go smaller unless you have a lot of west facing windows.

Total aside - insulating between floors for temperature is a old fashioned idea and doesn't help. Do it for the minimal sounds barrier - fine. But it is terrible for that also....

Also - 3 tons up has 4 returns. This was partly for zoning, but your house should have at least 2 returns per floor since our house does (total of 8 returns). I would expect your house to have 10 returns given the sq footage.

Am I reading you right that you have 3000+ sq ft per floor? I really think you would want some zoning at that size - as in more than 1 zone per floor. We have ours for our master suite since we like to sleep in the 60-65 degree range but our baby does not....