Best approach in general to a hot upstairs?

[Route246]

My house is mostly one level but has a bonus room over the garage. The garage is uninsulated with drywall. The bonus room and the garage both face west and get the afternoon sun. The bonus room and attic are well insulated, and the west-facing window in the bonus room has that reflective window film professionally applied.

Still, the bonus room runs about 5 to 10 degrees hotter than the downstairs. I live on the downstairs and my son lives in the bonus room, which makes it hard to agree on a temperature for the thermostat. Comfortable for him is cold for me, comfortable for me is hot for him.

Options I'm considering:

1. Ductless mini-split. I know these work well and are expensive.
2. Roof ridge vent. Not very expensive, seems like it would help.
3. Dual zone AC. Existing single zone HVAC is in the garage.
4. Attic fan with a thermostat. Attic has vents on the north, south, and west facing sides.
5. Increased roof vents. Attic already has the appropriate number of roof vents, but maybe more would help.

The roof shingles are regular three tab asphalt shingles. Roof is original to the 2004 home. Tentative plan is to replace the roof shingles in the next few years.

Thanks for any input / thoughts / opinions.

HIghest powered attic fan you can find should help quite a bit. It gets very hot up there. Also, laying out extra insulation in the attic space if possible. We have three of them in the house and one in the garage and it makes a huge difference. You will need to replace motors depending on their use because they run a lot and run hot. I've replace motors 3 times already and have a spare waiting. There are YouTube videos showing how to replace the motors.

 

[jazz4cash]

We had an attic fan in a house years ago and I was really surprised at how effective it was. I recommend it.

Same experience here. Ours ran on a t-stat in summer and a humidistat in winter (midwest).

 

[pacergal]

I also would start with window AC, then go attic fan if still too hot.

 

[Newventurer]

Right now as I am reading this I have a team in the attic installing a new ‘zone’ off my 1 unit. I have a two story and the one unit controls the upstairs and down stairs with individual thermostats using motorized dampers in the ducts. Now they are adding a 3rd zone as they say there is sufficient air going to the upstairs when it’s called for to accommodate an insulated and closed in attic space (331 sq ft) the zoned systems are controlled by a computer board at the unit and installation requires proper balance of the system on both the supply and the return side. The board in my unit can accommodate a total of three zones. The difference between a zoned unit and multiple units are that you have to choose between heat or air in a zoned unit, whereas with two units you can have one on heat and one on AC if you really want that. Also there is no redundancy with the zoned unit, but you only have to maintain one unit vs. two. I considered putting a mini-split in the attic space but it was $4k+ and adding a zone to my already zoned unit is $1250.

 

[Jerry1]

You will need to replace motors depending on their use because they run a lot and run hot. I've replace motors 3 times already and have a spare waiting. There are YouTube videos showing how to replace the motors.

I don’t know this to be true (no personal experience) but I had a guy over to quote my attic insulation and he proposed putting in a DC motor fan. He said they last a lot longer. His exact words were that he hasn’t had to replace one yet.

 

[GrayHare]

I've had three attic fans, all died within four years of installation.

 

[Jeffman52]

I had four solar blasters put in when I had my roof replaced. They are venting the attic at all times. But one thing I have been considering since we live in a 2 story with a basement is installing some venting (and a fan/blower) from the basement to the upstairs. The downstairs can feel fine, the upstairs can be warm, and the basement is cold. Its not horrible but I keep thinking it would be nice to move that cooler air in the basement to the upstairs in the summer. There is a laundry chute I could probably add a 10 inch pipe next to it without much effort, then install a fan and thermostat to move that cold air up the pipe and into the upstairs.

Who knows.. just a thought ... what would be the downside to that?

 

[GrayHare]

Pushing cool basement air upward will pull humid outside air into the basement, making for a damper basement.

 

[Jeffman52]

Ahhhhhhhhhhhhh thanks.... I run a dehumidifier down there, but it might cause mold and humidity if I screw with that. Thanks

 

[brucethebroker]

Inflation Reduction Act offers tax credits for heat pumps, including some ductless mini-splits. Nice article here: Heat Pump Tax Credit 2024: What You Need To Know

 

[SecondCor521]

Thanks to all for the suggestions and input and advice.

Right now I'm leaning towards insulation between the garage and bonus room (ceiling and floor respectively) and an attic fan and then seeing where we end up with those two things. I probably won't do a ridge vent. Putting a fan to vent the garage is also an option.

I appreciate the suggestion of a window AC unit but I am ruling that out as an option because I think they have very negative curb appeal. (The bonus room window which faces west also faces the street and is very visible to the street.)

Continued comments / suggestions / advice welcome.

 

[homestead]

I struggled with hot upstairs for years with noisy window AC's. I finally installed a 12k btu ductless MRCOOL heat pump and it solved all of our issues.

 

[Route246]

I don’t know this to be true (no personal experience) but I had a guy over to quote my attic insulation and he proposed putting in a DC motor fan. He said they last a lot longer. His exact words were that he hasn’t had to replace one yet.

Never heard of a DC motor for these attic fans. Need to investigate that.

I've had three attic fans, all died within four years of installation.

Ours have lasted 4-6 years depending on duty cycle. I'm getting pretty good at replacing the motors. This video on YouTube is pretty good and there are others. I believe GAF bought out the company that made our fans. The motor, thermostat and fan setup is identical. I get a kick out of the sterile setup the guy in the video is working in because ours are nothing like that. I need a full Tyvek suit and respirator mask when I go up there. The trick is to have all of the tools handy when I go up there because I don't want to be crawling back and forth. Ours are on 20A circuits and draw quite a bit of current when starting up and they do move a lot of air. I've gone up on the roof and felt how much is being exhausted. I had one put in the garage and even when it is over 100F in the summer the garage stays remarkably in the 80s with no AC, just the fan pulling out the 160F hot air at the peak of the roof. I'm not sure where the cooler thermal mass is coming from but the garage does stay much cooler than outside. Before that fan the garage would heat up over 100F on hot summer days.

 

[ERD50]

Thanks to all for the suggestions and input and advice.

Right now I'm leaning towards insulation ....Putting a fan to vent the garage is also an option.

I appreciate the suggestion of a window AC unit ....

Continued comments / suggestions / advice welcome.

I think you missed two of the best and simplest, low cost options (below). I know from experience that both/either of these can help. Our newer thermostat had the option to run the fan 20 minutes of every hour, rather than continuous. That was enough to help even the temp between upstairs/downstairs.

Easy and cheap, and if you need more that that, you haven't lost much of anything.

I found that running the fan on the house HVAC system continuously kept the air mixed and closer to the same temperature.

Try the register vent fans you can get for about $50 on Amazon.

 

[Texas Proud]

You can always buy a portable AC unit and just vent it at the window... nothing bad looking IMO...

We had some of these at my old job and vented above the drop down ceiling in the computer room as it got hot... worked very well...

 

[SecondCor521]

I think you missed two of the best and simplest, low cost options (below). I know from experience that both/either of these can help. Our newer thermostat had the option to run the fan 20 minutes of every hour, rather than continuous. That was enough to help even the temp between upstairs/downstairs.

Easy and cheap, and if you need more that that, you haven't lost much of anything.

Neglected to say we already do the former.

I've thought about the latter but don't like the idea of cords running to an outlet from the register vent or having to replace batteries if there are any battery powered versions.

 

[Blooming Late]

Fans and insulation are better long term solutions, and they might work, but a small window AC unit would fix the problem immediately. We had a two story condo with much the same issue, and the window AC 100% cooled it down.
Not too many things are cheap and effective, but that sure was.

 

[BasketCase24]

I'd recommend finding the problems before you start installing solutions.

Is the attic too hot? Is there excess humidity? Then additional attic ventilation can solve problems. Start simple, like ensuring your "goes in" vent paths (such as eave vents) are clear, then do the same thing for the "goes out" paths. (Keeping loose fill insulation out of eave vents can be a challenge without shields of some kind.) Make sure that there's a balance between inlet and outlet surface area. Green Building Advisor has a lot of information about energy conservation in general, and attic venting in particular. IF your flowpaths are balanced, then perhaps additional powered attic ventilation will help. Make sure it is thermostatically controlled AND has fire fuses, to keep it from providing air flow in a fire.

 

[bigadventure]

The answer is very simple. Turn the thermostat fan to ON. Run it 100% of the time in the summer. It will balance the air and move the heavier cool air upstairs.

 

[bigadventure]

In addition a newer Honeywell T9 thermostat would help. You can add multiple wireless temp sensors and heat/cool those rooms, by choosing active rooms or selecting the rooms.