Heating & Air Conditioning Building a Home

Help with custom home HVAC planning

3 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!

Comments (3)

Shola Akins
3 years ago
last modified: 3 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
3 years ago
last modified: 3 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.
Related Discussions
Help needed on new HVAC for my house
Q
Comments (27)
I think the rheem quote looks good. If its 8-grand less thats a major reason to go with that quote. 95% efficient 2 stage furnaces are plenty comfortable and efficient. A good thermostat will make it run in the low-stage most of the time. True modulating or 3 stage furnaces are more comfy but maybe its overkill. Just make sure your not oversized. Remember 95% efficient furnaces put out 15% more heat than the same size 80% efficient furnace. FYI - those rheem A/C's in the quote are plenty efficient also and RHEEM makes good quality stuff I think.
...See More
older house, new hvac diy help!!!
Q
Comments (18)
Yes, the mastic stuff is the bomb! I had used it on a chlorine leak scrubber system some years ago. The trick is to buy or mix to just the right consistency and then you are basically painting a plastic seal or your chosen thickness. I too think the aluminum duct tap is expensive, but it is approved, gives a good smooth interior, and when used over the mastic I will bet it stays in place giving the best of both. We used IR to check our electrical connections in the plant. 480 volts at 100 amps generates measurable heat when the connecting screws are loose and that uses power. So, though I have not had the energy audit I have purchased an IR gun (got it cheap!) and am finding lots of unexpected holes. I was also surprised to find the walls did not show the heat level I expected. It turns out that the previous owner did some exterior wall insulation. A 1950's house here in California had next to none. This means that my AC unit is oversized, not having that loss to compensate for. It will still work out. I will have to fine tune for efficiency now, but if I ever build the extra conditioned floor and attic space it will be about right. The furnace is still oversized, but that is why I went for the two stage. It just hit me that what most of you guys are talking hard duct as it is normal. That stuff is better done by a professional unless you have all the equipment and can afford to practice (waste cost). But then you would, if you did your research, nearly a professional. I am doing Flexible ducting now because it's easy and my final configuration will not be fixed. My attic space and roof may be changing in the future if I can find the money. At that time I will be doing hard duct, wall stacks, and the like. That is major and will probably be contracted. Right now I want to spend as little as possible to get my system working. I have a wall heater and window air, so the efficiency increase could be as large as 50%. Just replacing my water heater with a tank-less last December gave me about a 15% reduction in gas usage and I think we are using more because it doesn't run out in the shower anymore. If the HVAC works as well I may save over $100 per month this summer on AC and an unknown amount next winter on heat. Hey, I just looked back at this and my other posts and realized that they are WAY long. I apologize. I am more used to writing memos, letters, and manuals. Give me time. I will get used to shorter posts.
...See More
HVAC for addition only, A/C for whole house - Help with Setup
Q
Comments (8)
There is no "adjustment" of the duct size, you always need to start by doing a Manual J load calculation to determine the right size of equipment, and Manual D calculations to figure the duct system. The 40K BTU and 3 ton were just numbers I was throwing around as an example. I was just guessing, which is exactly what you should NOT be doing when planning a new system. The problem with the setup you are proposing is that you will need expensive equipment to do it properly. 2 stage/modulating furnace and zoning systems do not come cheap. If you went with separate systems, you could just go with basic, no frills equipment for each part of the house that would be cheaper, easier to install, and easier to service. There is no "HVAC 101" resource that would singlehandedly teach you everything you need to install this system correctly. It takes years of training and on-the-job experience. The best place to get information will be the documentation for the products you are considering. As an example, I am linking below an installation manual for a zoning system. I would read through it and make sure you understand everything and would be capable of following those instructions yourself. Here is a link that might be useful: Lennox Harmony III Installation Manual
...See More
Seattle: Help choosing HVAC upgrade in early 1900s house
Q
Comments (38)
TC: they aren't trying to cheat you as the guys said. When I lived in Seattle, rates were so low that I had to call them since my first 2-month bill was $12. I thought it was a connection fee, but it wasn't. Now, your rates are slightly higher than mine are here in the East. When gas was more expensive a few years ago, the cost difference would have meant more than now. But your gas rates have probably gone down as the electric rates went up (still paying off those 5 nukes that never got built?). The Seattle area has such a mild climate (for being that far north) that heat pumps work just fine. So its not a surprise that they get recommended now that they are more efficient. (And lets not start a war over the definition of efficiency.) Another consideration perhaps. A heat pump will run year round in your location. An AC unit may only run 2-3 months in Seattle, if that much. Hopefully the AC unit will last longer from non-use. Which also means you don't really have to go with the higher SEER number since you are not going to see any ROI. 14-15 would be fine.
...See More
mike_home
3 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.

Help with custom home HVAC planning

Comments (3)

Shola Akins

David Cary

Related Discussions

mike_home

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US