Heating & Air Conditioning Building a Home

Help with custom home HVAC planning

5 years ago

Hi All - I hope some HVAC experts here can give advice on what systems would work best for my home.

I am building a 3600 one-story home, and all ductwork/furnace, etc will be located in the basement. The house is grouped into three areas - the left wing with 2 bedrooms, the center of the home with the main living areas/kitchen, and the right side with a couple more bedrooms.

I met with an HVAC sales person today to go over what would work best for the home and was given three options for systems (good, better, best):

Trane XB 14 80% Furnace 14 seer AC
Trane XR 16 80% (single stage) Furnace 16 seer AC
Trane XV20i with XC80 Communicating furnace and variable speed A/C 20 SEER

In all cases, there would be two units (4 ton, 2 ton) with the 4-ton unit zoned for the left/center areas of the home, and the 2 ton dedicated to the right.

There is a HUGE cost difference in between these options, and some research led me to learn that the first option of an XB 14 is actually a discontinued model!

Understanding the large footprint of the home and the desire to have 3 areas separately temperature controled - can someone please advise a) if these options make sense or is there a better way/brand to do it, and b) is it really worth it to step up from good to a better or best option? Going from good to better is a 6K jump and better to best an additional 8K.

For climate reference I live in GA.

Thank you!

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Comments (3)

Shola Akins
5 years ago
last modified: 5 years ago
Go with two units that have two stage compressors. I am in Atlanta and I went with the carrier performance units for each floor which work perfectly.
David Cary
5 years ago
last modified: 5 years ago
I live in Raleigh so close climate.

My first custom build was in 2008 and I spent about 20k on Carrier Infinity. 3 ton and 4 ton units. The 4 ton was zoned. 4000 sqft over 2 floors. Lots of trouble. Lots of repair costs.

My second was 2019. 3800sqft over 2 floors. Did Trane, unstaged, unzoned, two 2 ton units and used a ducted mini for the master bedroom.

Spent $15k (total installed) and it just works. Now I haven't been here long enough to really know about reliability but it is hard to spend a lot of money on basic equipment.

The lesson I learned from the first house is that you don't need all that complexity and cost and unreliability to have a good system. We have the XR15 (its a heat pump). I actually have several XR15s of various ages in various rental houses. They have been great.

Yes a staged system will help with humidity control in both shoulder seasons and poorly designed house/HVAC. Yes the more expensive systems will save you a small amount of electricity. You are wickedly better off just putting solar PV on your house. My house is net zero energy with $18k of PV. Using seer 15 equipment.

I don't see why you would need or want furnaces in Atlanta. Your electricity is so cheap and your winters are so mild. You get more penetrations from chimneys, you get greater install cost. And for that, you pay more to run the furnace. Now, I truly don't know your rates but I do remember that GA is generally a bit cheaper than NC for electricity. In general, a SE climate does not financially benefit form a furnace. People put them in because of inertia/misconceptions.

I was just thinking, your furnace is in the basement and they were quoting 80%? When I had a basement, our builder stated that 90% was cheaper because of the exhaust install cost. 80% need a real chimney while 90% just a side exiting PVC pipe. So while the 90% unit cost a few hundred extra, the overall cost was less. Maybe that changed..... Maybe someone likes installing chimneys...

Maybe you should get another quote.
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mike_home
5 years ago
Are you the builder of the home? If so then you need to find a good HVAC contractor. The first thing which needs to be done is a heating and cooling load calculation. This requires using all the dimensions from the house plans and entering into a software program. If the contractor won't do this, or wants to use some rule of thumb based on the size of the house then you need to keep looking for another contractor. A calculation of duct sizes also needs to be done.

I think a 6 tons of cooling for a 3600 sq feet new construction seems over sized. Have you decided how much insulation you will be installing in the attic and walls? Given this is a ranch the biggest loss will be through the roof and attic. It makes sense to invest in upgrading the insulation rather than buying bigger and more equipment.

Post your electric and gas rates. The operating costs of a heat pump in GA may be lower than a 95% efficiency furnace. If you do install gas furnaces I suggest getting the higher efficiency and exhaust out the side of the house as David Cary suggests. If you are going to zone one of the systems then a 2-stage variable speed furnace or air handler would work better. Most contractors are not good a zoning so find one who you believe can do it properly.

Once you have you determined the HVAC needs you can start the discussion of which equipment you should consider buying. That is the last step and not the first.