The nests (and many other thermostats) let you operate the fan independent from the AC.
I configured my fan to run 15 minutes every hour regardless of whether or not the AC/heat is running and it fixed all of my issues with the upstairs being way too hot.
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.
I dont have HVAC specific advice for you, but I've lived in a well isolated house in a hot environment (42C max temperatures) and what we did was open basement windows and atic windows, and have a fan point out of the attic window. This created a draft that exhausted the hottest air in the house out, and while upstairs was always hotter than downstairs, it was much more bearable than without.
I imagine a similar setup would help you get the cooler air from downstairs up, and a big advantage is that you can try it with very little cost and commitment.
I don't know how your house is configured, it might not be a solution for you. We have a pretty habitable attic, not those insulation filled dens I see in American houses, so it was pretty easy to try it for us.
Also, we opened and closed the windows every day, we didn't leave it open overnight.
Just had to solve this problem myself recently. Same issue, upstairs stifling while downstairs stays nice and cool. For a whole year I just ran the system a bit colder, but that made the downstairs freezing in order to make the upstairs feel normal. Not to mention all of the energy waste running the system for so long, my home is 2300 ft.² so I went for the dual zone with a mechanized damper. You could save on the cost by installing a manual damper that you could adjust as needed so far the system marks very well and my upstairs can get nice and cold, while the downstairs is a cozy warm temperature. I paid an HVAC company $2,300 for this to be done, but the manual damper would have been just $600.
Other options I considered though were going to mini split route like the other comments suggest, or if your HOA is strict about even that, you could even use an indoor AC or two, and have the exhaust vents blowing out the window.
Yeah, these also work pretty well, OP. Just make sure you get the ones with two hoses, not just one for exhaust. The single hose ones create a vacuum in your house that sucks in outside air making them significantly less efficient.
Oh dang I didn’t even know there was a two hose type. It makes sense though since it would be sucking the room air through to exhaust outside, creating a vacuum
Jeez at 2,300 feet you should have two central airs already or a vastly optimized system that should have handled that. That’s shitty code or builder unfortunately.
The mini-split route idea is a great solution, but I am wondering if you have an unvented or poorly insulated attic that is a contributing factor to your problem. If your attic space isn't setup properly and you throw a mini-split at the problem, it is sort of like pumping water out of a boat without fixing the leak that is flooding the boat. Even something as "simple" as a powered attic vent could help in HVAC performance and operating costs. If the hot air can't vent or your insulation is inadequate, it just stacks down and heats the top floor.
The other thing I would be looking at is if the HVAC run up to the second floor is done properly or if the dampers are not right. A house that size really shouldn't have much trouble if everything is balanced right.
Closing vents on the first floor and leaving the second floor open will increase the wear on the fan and may decrease efficiency if not enough air can be moved through the open vents. Knowing how bad an idea that is would require some measurements and math.
Having the nest with a second temp sensor would just force your HVAC to work harder to cool the upstairs. The single sensor nest can be a smart move to reduce costs with the higher degree of control.
Having dampers installed does more or less the same thing as closing vents, but with a higher cost. A zoned system is expensive and kind of silly on a house of that size.
The mini-split route idea is a great solution, but I am wondering if you have an unvented or poorly insulated attic that is a contributing factor to your problem. If your attic space isn't setup properly and you throw a mini-split at the problem, it is sort of like pumping water out of a boat without fixing the leak that is flooding the boat. Even something as "simple" as a powered attic vent could help in HVAC performance and operating costs. If the hot air can't vent or your insulation is inadequate, it just stacks down and heats the top floor.
Unfortunately, I don't live in a free-standing house. It's a townhouse, so it's connected to other units so I don't think that I can make changes to the attic.
The other thing I would be looking at is if the HVAC run up to the second floor is done properly or if the dampers are not right. A house that size really shouldn't have much trouble if everything is balanced right.
I don't seem to have any dampers at all as far as I can tell.
Having the nest with a second temp sensor would just force your HVAC to work harder to cool the upstairs.
Yeah, I get that I would be pushing the HVAC system to simply be on more, but at the very least I could actually set the temperature upstairs instead of having it fluctuate so wildly. Often, I'll set the temp low at night to be more comfortable. It'll be to the point where I'm basically freezing with the sun down. But then in the morning, when the sun rises it's unbearably hot.
The single sensor nest can be a smart move to reduce costs with the higher degree of control.
What do you mean by this?
Having dampers installed does more or less the same thing as closing vents, but with a higher cost. A zoned system is expensive and kind of silly on a house of that size.
So there's no real reason to get dampers installed then?
If you’re in a townhouse, you have an association. The association would be responsible for the common attic and its insulation. Bring this concern to the attention of the board. Could be other people have the same problem and the fix could be attic-related.
LOL good one! Anytime there is damage to common areas, the affected homeowners have to file a claim on their HO6. Its the stupidest thing I've ever encountered. Roof leaked and I had water damage in the ceiling. I had to file a claim for the HOA's $5k deductible.
You would have to get a GC out to inspect the attic and then give you a written recommendation of alterations, which you then would take to your association. Talk with your neighbors and see if they have the same issue, them jumping in on the issue would offer a greater chance of approval. It is possible the association may pay for it if the problem is attic venting, insulation would likely fall on you.
Forcing the system to run more to compensate for the upstairs would drive up your electric bill and may not actually help if the problem is in the attic or balance of the HVAC. You could set the temp lower at night to accomplish the same thing as dual sensors, but you still are just throwing money away that should be better spent on addressing the issue directly.
Having a nest vs non-smart thermostat allows you to set schedules in a smarter way than a regular tstat.
Having dampers allows you to balance the system so the downstairs gets less air than the upstairs, instead of you having to go around closing vents and the downstairs would be cooled better than just shutting vents and sending most of the air upstairs.
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.
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.
Haha well true. I just presume that if you have dampers built into the system by an HVAC company that steps would be taken to ensure it doesn't mess up your system.
I've never seen manual dampers that smart. 🤷 Give closing up downstairs a shot and if your evaporator turns into a block of ice, well, then you let it thaw and know your need more air flow.
Haha. Well I don't mean the dampers themselves are smart. I mean that the HVAC companies will do pressure checks make sure things are flowing and vented properly if they are adding in dampers in particular areas.
If you close a register all pipes and joints between the furnace and the register will be under more pressure than designed and can force the joints to cause leaks, this can push humid air into joist spaces as well.
Theres lots of potential issues, putting a damper as near to the source as possible prevents this issue.
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.
Buy a 3D printer to make a custom cover. 2 years later you'll be too busy maintaining ("upgrading") your printer that you'll forget why you got it in the first place.
If this is the ceiling and a small room I would put a utility ceiling in. Where I live for a room like a simple washing room that would be 150 euros tops and you can always run new wires and get to the old ones without hassle. Nothing else will make it look pretty.
I think people are voting on the practicality of this suggestion, but I think it's a hilarious image.
I had a super soaker 30 when I was in early double-digits and it was so much fun to load stuff other than water in it.
If it were me I’d design and 3D print something to mount around it that would be held together with either rubber bands or possible screwed together. But I realize that is outside of most people’s skillset. Maybe you could get somebody to design something and get it printed online. But I guarantee it would take a couple of iterations and probably cost upwards of a $100.
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