Hi all. I have a 2 storey, ~1200 sq ft home in a hot climate. I have a single HVAC unit…central air and ductwork, electric AC/heat. There is no zoning to the system. The thermostat is downstairs.
Everything is great in the winter months. But in the summer months, the upstairs is absolutely stifling. I don’t have a thermostat upstairs, but it feels like it stays at least 10 degrees hotter than downstairs. I get that hot air rises, but considering the bedrooms are upstairs, it makes things unbearable.
My HVAC air handler and condenser are from 2008, so they are rather old and I’m likely to have to replace them soon. When I do so, I want to figure out how to keep the upstairs more comfortable.
Before I start asking companies for quotes, I want to figure out what I’m doing first. Some things I’ve come across…
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Install something like a Nest system with a remote temperature sensor. Place the temperature sensor upstairs and have the Nest use that to figure out when to cycle the AC on instead of the downstairs thermostat. I could install something like this myself instead of needing an HVAC company, though it isn’t necessary very efficient.
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Consult with an HVAC company about having dampers/a zoning system installed. From what I’ve read online, it seems like people are saying this isn’t really financially worth it. But if I’m at the point where I want a new system anyway, would it make sense?
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Window AC units are an obvious “solution”, but I can’t have them due to the HOA.
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I have read of suggestions of people saying to close the vents downstairs in the summer, but it seems like this is bad advice, as supposedly it will stress your HVAC and cause it to fail prematurely.
Edit: Just found a new one…setting the fan on the thermostat to “on” instead of “auto”. Although some people seem to warn of mold growth.
Would love to hear any and all suggestions. Thanks!
Not an HVAC tech, but where are your air returns located? I would agree that keeping the fan on will help mix the air in the house. Closing all the registers on the lower floor might stress the system, but you could close a few I’d wager and be safe.
Same issue as you. Second floor bedroom above the garage gets really hot, but we can’t stick a window unit out the front of the house because it would be conspicuous, ugly, and prohibited by HOA.
What I do have is access to the attic part that is adjacent to that room. So what I’m thinking of doing is punching a hole thru the drywall of the bedroom into the attic, mounting a window type AC unit in there so the attic is the “waste heat” side. I would install a drip tray to handle the condensation, and maybe something else to vent additional moisture and heat out of the attic. They make solar powered fans you can install that pull air out the top of the roof.
Close the downstairs registers?
Right here @dingus.
During the summer, close the down stairs registers.
Also yes, if your system can, leave the fan blowing, that way you keep the air circulating.
Our thermostat is downstairs, and this is what we do.
I know multiple people say to close the downstairsregisters, but HVAC sources that I look at say that it greatly stresses the system if you do this and that it’s a bad idea.
Install a mini-split upstairs, it will keep that zone the correct temperature using it’s own thermometer. It can be downsized a bit as the main HVAC unit will help it out using your existing ducting.
For exact design, I would say have one per bedroom or a multi-zone mini-split that can cover each bedroom.
Many (most?) mini-splits are DIY friendly as well, if you want to save a bunch of money and install it yourself.
Just piling on at this point, but we made 2 changes last spring that made summer so much more tolerable in our house.
- More insulation. I bought a cheap thermal camera on Amazon and found entire closets and a bathroom with no insulation. Those rooms are a solid 10+ degrees cooler now.
- More ventilation. Half my house didn’t have any soffit vents, but had attic vents. Adding soffit vents made that half the house 5 degrees cooler all on its own.
And we haven’t found ourselves needing it, but a mini split has popped up a lot here already and is a great idea.