We are finishing our basement and blew in insulation in the ceiling, it made a huge difference. I'd start there.

With a hot garage below and a sloped ceiling above there isn’t much room for insulation. I would find out what is in there now first, then have a heat load calculation done on the space. That will tell you what your options are pretty quickly and let you compare the various costs. If the spaces are already insulated a competent professional can tell you whether increasing the duct size, rebalancing the system, adding a return, replacing the windows, etc. will help or whether you just need more cooling capacity regardless whether you do some or all of them.

From your description it sounds like the ceiling of your garage is connected to the trusses that support the floor of the room and the ceiling of the room is connected to the underside of the roof trusses without much of a gap. If that’s the case you’re going to have a lot of thermal bridging (heat conducted through the trusses to the floor and ceiling) that insulation won’t fix so I wouldn’t assume that will solve the problem if it isn’t there. A good heat load calculation will account for that.

quote:

Originally posted by DaveL:
With a hot garage below and a sloped ceiling above there isn’t much room for insulation. I would find out what is in there now first, then have a heat load calculation done on the space. That will tell you what your options are pretty quickly and let you compare the various costs. If the spaces are already insulated a competent professional can tell you whether increasing the duct size, rebalancing the system, adding a return, replacing the windows, etc. will help or whether you just need more cooling capacity regardless whether you do some or all of them.

Who would I talk to to have a heat load calculation done - an HVAC company? Someone else?

My first choice would be a mechanical engineer. A good HVAC contractor could probably do it but I would want someone I really trust because it’s in their interest to recommend a solution they can provide. An engineer won’t have that problem.

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Originally posted by squad13:

quote:

Set your thermostat fan to ON instead of auto

Does this method bump up electric costs?? Bump up to the point it wouldn't be worth it?

I can’t say I’ve noticed a difference but I haven’t really tried to compare either. The hvac guy that told me this said that is how they are supposed to run and we’d spend more replacing fans because of the constant cycling. But in 25 years of owning houses I’ve never had a fan die. So can’t say that’s an issue either.

It makes complete sense to me when a thermostat is in one room and the entire floor is on the same zone.

Just found this site that basically says the same things. https://www.hydesac.com/use-th...ts-fan-auto-setting/

quote:

Originally posted by frayedends:

quote:

Originally posted by squad13:

quote:

Set your thermostat fan to ON instead of auto

Does this method bump up electric costs?? Bump up to the point it wouldn't be worth it?

I can’t say I’ve noticed a difference but I haven’t really tried to compare either. The hvac guy that told me this said that is how they are supposed to run and we’d spend more replacing fans because of the constant cycling. But in 25 years of owning houses I’ve never had a fan die. So can’t say that’s an issue either.

It makes complete sense to me when a thermostat is in one room and the entire floor is on the same zone.

Just found this site that basically says the same things. https://www.hydesac.com/use-th...ts-fan-auto-setting/

With traditional air handler the "fan on" generally runs the fan at the high air conditioning speed continuously, and this will take some electricity to do so. On the newer variable speed blowers the "fan on" setting can be set to run at a very slow speed and this works well in helping even out the temps through the house. Still if the garage room is far from the air handler, has inadequate ducting, and/or is not insulated as well, this probably won't be the solution. Installing the smallest window AC you can find is all it should require to cool that room.

If the garage door isn't insulated, it's an easy fix and it will help some.

quote:

Originally posted by BB61:
We are finishing our basement and blew in insulation in the ceiling, it made a huge difference. I'd start there.

THIS. Blown in insulation is the best bang for the buck, R-30 usually costs less than $1 per sq foot of insulation and pays for itself in a few months. This is the first thing I'd investigate, then check on how hard it would be to put a return there, then go down the route of adding an a/c.

Do you park vehicles in the garage daily?

This message has been edited. Last edited by: jimmy123x,

Booster fan in ductwork to the room might just solve your problem.

Insulated garage door.

Insulated garage.

Additional HVAC vent in bedroom.

Additional HVAC return nearby bedroom.

An exhaust fan running all of the time will pull air out of the room. Sort of how leaving a bathroom fan on all of the time is helpful in keeping a non-conditioned powder room more temperate.

Had the same problem... I live part time in Salt Lake City. Go old school and do a roof swamp cooler. The wifey and I did that we get too cold during the latest heat wave and have to turn it off. Costs about $25/month in electricity. About $1300 to have installed 3 years ago. I do have a maintenance company bring it to life and put it too sleep in spring and fall for $75. They do make your roof look ugly.

Same situation for our MBR (~20’ x 25’).

Our central AC typically can keep up with ‘normal’ temps in our area, but with an extended heat-wave of about 3 weeks with temps in the low to mid 90’s I knew that the room would become uncomfortably hot.

I purchased a 14K portable AC unit (LG from H-D) and it has performed well and is able to chill the room down nicely. We will typically turn it on at around 8 or 9 PM and then set the controls to auto-shut off around 3 AM.

The unit may not be as efficient as a window unit, but to me the convenience of not having to mess with a window install along with being able to easily move it into storage when not in use, or to easily move it to another room was a favorable consideration in the purchasing decision.

Rob

If you don't have a "laser thermometer temperature gun" get one. Check each wall in the room and garage. Measure the garage door inside and out during the peak of the day and first thing in the morning. Take notes. Address the biggest issues first.

Regarding the garage. Once the garage is heat soaked it will dissipate the heat through the framework into the house. For hours through the night.

Does your garage door face west? Mine does. The outside surface gets up to 145 degrees when the temps get to 100+. After upgrading to a 2" insulated door the inside of that door gets to ambient temp. My garage used to be an oven in the summer, not anymore.

Good luck.
-TVz

our masterbedroom is over the garage,

the ceiling is insulated and sheetrocked (code)

the foreman that was in charge of the build made sure we had a good flow, we have 3 vents in the room, and one small return ,

room is ~20x20

with 2 windows that face the sun in the evening,

stays comfortable even on the hottest days,


I also insulated the garage all around, and it has an insulated door

the garage in not HVAC controlled, but I may add a mini split in the near future,

hottest days now it will get to almost 85, coldest nights maybe 40

Our kitchen is the hottest room of our house, and I used a portable ac unit to cool it down. works great and was about $400. We have 2 Three panel sliders in the kitchen, so a window unit was out of the question.

If you have sloped ceilings just remember that if you fill the space between the roof deck and room ceiling with insulation you have to leave a space just under the roof plywood for airflow from the soffit vent to the ridge vent or that plywood will rot. I had to redo a roof some dubber had done the wrong way and inside two years the roof plywood against the insulation was black with mold and rot. Rafters were still usuable but barely.

This message has been edited. Last edited by: Blackmore,

I like the idea of setting the fan to “on”, at least will give it a try.
Article says in addition to getting better equalization of temps, you get constant filtering of air.
We have solar and our electricity now is basically free.

quote:

Originally posted by gjgalligan:
Booster fan in ductwork to the room might just solve your problem.

That sure solved our problem. We built our home about 7 years ago and had a FROG room (finished room over garage) built and took great care to insulate it well but it still stayed about 10 degrees warmer when we moved in. Our HVAC guy came over and installed the little booster fan which turns on when HVAC kicks on at no cost and the FROG room stays almost the same temperature as all other rooms now.
Bearing started squealing on the fan a couple of months ago so I called my guy and he installed a new fan so I got a couple of pic's..he didn't charge us so don't know the actual cost but Amazon says $112.00

IMG_6571 (800x600)

IMG_6572 (800x600)

quote:

Originally posted by SummersAtTheLake:

quote:

Originally posted by gjgalligan:
Booster fan in ductwork to the room might just solve your problem.

That sure solved our problem. We built our home about 7 years ago and had a FROG room (finished room over garage) built and took great care to insulate it well but it still stayed about 10 degrees warmer when we moved in. Our HVAC guy came over and installed the little booster fan which turns on when HVAC kicks on at no cost and the FROG room stays almost the same temperature as all other rooms now.
Bearing started squealing on the fan a couple of months ago so I called my guy and he installed a new fan so I got a couple of pic's..he didn't charge us so don't know the actual cost but Amazon says $112.00

IMG_6571 (800x600)

IMG_6572 (800x600)

Interesting concept. Did the have to remive a lot of flooring or ceiling to install it? Does it install close to the room over the garage, or further upstream?