Window AC question

[TXNinAZ]

Hi everyone,

I'm in the midst of improving my garage and have an a/c question. I got a 10500 BTU GE window unit free from my dad, but I think it's way too small for my 3 car garage (650 sq ft with 9 ft ceilings).

I'm not looking for 70* in the summer, I would just like to take some of the edge off. The normal high air temp during most of July and August is over 110*, so I just want to bring the garage down into the 85-89* range, to make it survivable.

I have radiant barriers on both doors, and 1" foam board insulation, and will have the attic above the garage insulated before it starts getting hot again. Should I install this unit, or is it not even worth the effort? The recommended BTU output for a room this size seems to vary quite a bit

Thanks for the help!

 

[JimVonBaden]

Depending on how much you open and close your doors, that unit will do better than you think based on the info you gave. I had a two car garage in Vegas, similar temps, and a window unit smaller than yours would bring it down to the low 80's in summer. That was with the garage door in full afternoon sun.

Jim

 

[pattenp]

For that size of space when insulated well will take a unit of at least 14000 btu to maintain a comfortable temp. I'd guess your 10500 unit will probably run all the time to keep it 80 to 85 when it's 100+ outside. I have a 8000 btu window unit in a 450 sqft so so insulated detached garage and all it can manage running constant is about 15 deg. less than the outside on a 95 deg day.

 

[Gary S]

Worry less about AC size and more about the building. Insulate it well. At least R20 walls and R50 ceiling. Then you will find that 10,500 btu unit will do wonders.

If you don't insulate, you can't cool a garage 1/4 that size in your hot climate.

 

[TXNinAZ]

Thanks for the input, guys. I will be adding cellulose insulation in the attic above the garage between Christmas and New Year's. I'll get as much as budget allows, and hopefully get above R40. The big problem is of course the 24' of doors that can only be improved so much. I think with the foam board and radiant barrier, I'm still only at like R7

 

[Beaumont67]

I have a 24x30' garage, with no windows, 9 foot ceiling....12,300 BTU sleeve AC, for 720 sq.ft.
- 2 insulated commercial doors 8x10' each
- 1 insulated steel man door
- 1 ceiling fan
- R20 in 2x6 studded wall & R40 bats in ceiling (12'" thick Ruxol)
Summer heat gets like 95 degrees F....and very easy to get garage temp. down to 72F.
Remember, garages are open design and cool better than a AC in the living room, of a home.
- so the cold air in the house, doesn't travel down the hall way well and into the bedroom(s)

 

[6768rogues]

If you keep the doors closed and run it in advance, probably overnight, I think it would work well. If you turn it on in the heat of the day after driving a car in with a hot engine, you will be disappointed.