Garage AC

[DIY Rookie]

Did a search couldn't find anything but probably just me.

So I have a 525 SQ ft insulated garage. 8 foot ceiling. I've researched and it says I need a 12k BTU window unit. I'm wondering if any of u have used a window unit in your garage if u could tell me if I could get away with a 5000k BTU unit? I have 2 fans in my garage to help push the air around. I'm not looking to get it ice cold or anything but maybe if I can get the garage between 70-75 I'd be happy. Let me know what u think and what u think the minimum size BTU window unit I could get away with. Thanks

 

[chad215]

a 5k window unit isn't going to do much at all in that big of a space. I doubt you would notice much of a difference. Those are really sized for small bedrooms. But I'm in TX where it gets really hot and humid.

 

[Yankeefarmer]

Did a search couldn't find anything but probably just me.

So I have a 525 SQ ft insulated garage. 8 foot ceiling. I've researched and it says I need a 12k BTU window unit. I'm wondering if any of u have used a window unit in your garage if u could tell me if I could get away with a 5000k BTU unit? I have 2 fans in my garage to help push the air around. I'm not looking to get it ice cold or anything but maybe if I can get the garage between 70-75 I'd be happy. Let me know what u think and what u think the minimum size BTU window unit I could get away with. Thanks

If you have a 5000 BTU unit you want to try, just do it. Too much depends on the building’s exposure to the sun and number of air changes; square feet doesn’t tell the whole story. My shop will stay comfortably cool without AC if the overhead doors remain closed. If they are open for only 10 to 15 minutes, the temperature will shoot up to where I want AC.

But if a load calc suggests 12k, and you have to buy one anyway, just buy a 12k. They have thermostats, so it’ll cycle if it can.

 

[Jakemedic]

I tried a 5000 btu window ac unit that I had already in a 600sq/ft garage at our last house. Didn’t do a darn thing really! I sold the house before getting an appropriate sized ac. In my new shop I have a mini split that is amazing for cooling!

 

[pbon]

If you run it 24/7, the little 5k might cool the garage down considerably. It won’t be able to cool it down quickly, like in a few hours, if you let it get to 100F in there. But leave it on full time, it will eventually cool the walls and ceiling and floors so it has less and less work to do. Since you have one, try it for a week to see where you end up.

 

[PoorUB]

I have a 900+ sqft garage. I used a 12,000 window AC for a while. It would cool it in all temps, but in extreme heat I had to leave it run as it would not catch up if started later in the day. I have since put in a 18,000 BTU AC and it will cool it down when ever. The extra 6,000 BTU was all it needed.

Figuring that way amounts to about 2 BTU per sqft. I would go with a 12,000.

 

[Jeepster04]

I think it depends on how much sun the garage gets. If its full sun all day long, no, that wont do much. My garage might get sun for 8 hrs a day, so I think that would work perfect. My garage hardly gets above 80F with no A/C if I keep it closed up, even when its 90+ outside.

 

[Crazyjake8493]

The 5000btu units tend to be junk, even if they're in an appropriately-sized room. There's a reason they're $150.

I wouldn't even try less than an 8000btu window unit, but 12,000 would be better. Assuming you're not running it 24/7, you want something that will bring temps down fairly quickly when you want to work in there.

I have a 9500btu LG inverter window unit in our house that I really like. It was $429 and cools the entire first floor of our house with two ceiling fans running. I don't use A/C in the garage enough to justify that, so I cool mine with a rumbly old 8000btu unit that got too loud for our bedroom.

 

[Syberia]

I have a 24,000 btu mini split in a standard 2-car garage in southern California. Has no problem maintaining 72 out there in up to 110 degree weather, but yesterday it really struggled after pulling in a hot car that had been sitting outside to work on it. I would not go with anything less.

Opening the garage door will also let all the cold air out, so you want something that will bring it back down quickly.

 

[PoorUB]

I have a 24,000 btu mini split in a standard 2-car garage in southern California. Has no problem maintaining 72 out there in up to 110 degree weather, but yesterday it really struggled after pulling in a hot car that had been sitting outside to work on it. I would not go with anything less.

Opening the garage door will also let all the cold air out, so you want something that will bring it back down quickly.

Are you certain thr AC is working properly? Properly charged? Coils clean? Filters clean? Blower wheel clean? Did it ever work well?

How large is the garage? How well is the garage insulated? How well insulated is the overhead door?

Keep in mind a car that has been run for some time in the hot California sun snakes up a lot of BTUs. I wouldn't base my AC capacity by being able to cool down the garage with a hot car just put inside. You might need 60,000 BTU or more to cool the car down.

H

 

[Jagmandave]

Unlike a house, I think you need to oversize the A/C for a garage. Mine is just over 600 sq ft and I also bought a 25K BTU unit. We get hot but we also get humidity, so the extra performance really helps in my shop......I don't need to leave it on all day or overnight, if I kick it on an hour before I want to work it's wonderfully cool and more importantly - dry - in the shop. I simply can't do the heat, so if it's hot in there I can't work, for the extra $20 a month it costs to run it, well worth it.

Bonus - mine has a heat strip in it so I can take the chill off in the winter. Worst I've seen was 39* in there, after an hour of running it was in the mid 50's.

 

[American Locomotive]

12k BTU sounds like a lot for just 500 sq ft. Shoot my buddy air conditioned his entire house ~900 sq ft home with just 10,000 BTU.

But it also depends on what you're trying to do. If you're looking for a "Turn it on and have the space comfortable in 30 minutes" solution, you're going to need a lot more power. Easily 12,000+ BTU. If you're looking for something that is "sized correctly" and will keep the space comfortable, but you will likely have to turn it on a few hours ahead of time - 8,000 to 10,000 BTU would definitely serve you better.

If you're looking for a more efficient solution, the 9,500 BTU LG Inverter unit mentioned above is pretty much the most efficient and quiet window unit you can buy right now.

 

[JRC3]

Maybe a 10K in MI. In SW Ohio I have I have 24x24 (575 sq) with a newish 15K through the wall. It was built in the mid 1980s and someone put some low density 1.5" foam panels behind the drywall. My overhead has a solid 1/4+" gap around the whole perimeter. No insulation in the ceiling and a 6' decked attic above with gable ends and small vents at each end. No shade and solid sun the whole day. If I crank my 15K unit on early or the night before it keeps it around 70, even last week when it was 97 and upper 90s for days straight.

A 5K aint gonna keep yours super nice but it will knock the edge the temp and drop some humidity. If you got it, run it for now, it's better than nothing. But if you're buying new, get at least a 10K+. buy once, cry once.

 

[PoorUB]

Unlike a house, I think you need to oversize the A/C for a garage. Mine is just over 600 sq ft and I also bought a 25K BTU unit. We get hot but we also get humidity, so the extra performance really helps in my shop......I don't need to leave it on all day or overnight, if I kick it on an hour before I want to work it's wonderfully cool and more importantly - dry - in the shop. I simply can't do the heat, so if it's hot in there I can't work, for the extra $20 a month it costs to run it, well worth it.

Bonus - mine has a heat strip in it so I can take the chill off in the winter. Worst I've seen was 39* in there, after an hour of running it was in the mid 50's.

600 sqft and 25k BTU?!?!
12K would have overkill it! I have a bit over 900 sqft and 18k of cooling, insulation is not as good as it should be. I can go out at 95F, turn on the AC and it feels great in there in an hour.

 

[pbon]

I can see how parking a hot car in the garage would make cooling more challenging.

 

[Jagmandave]

Exactly why I said you need to uprate it, that and opening those huge doors long enough to get that hot car in or out of the garage......

 

[American Locomotive]

When the space is down to temperature, opening the doors briefly will not impact the temperature of the space that much.

 

[JRC3]

Overkill BTU just means humidity never gets removed. Runtime isn't just about temp, it's almost equally about removing humidity.

Bigger is good if you want to leave the door up, or want to do quick repairs in a hurry. Otherwise you want it to run long enough the cool the surroundings including slab, walls, tools, cabinets and everything else and in the process removes that pesky moisture.

 

[BillK]

Detached garage or attached to the house ? How well is the door insulated and sealed ?

Do you heat it in the winter ? If so what size heater works good. Might give you an idea as to what AC might work.

 

[TractorJeff]

FWIW. I go out in the morning to turn on the 5000btu window A/C in my 950 sqft Shop. Outdoor ambient can be 60 to 75 degree range. By the time mid afternoon roles around it is 72 to 76 in the Shop. Outdoor ambient has been 80 to 100 degree range. I try to minimize opening the overhead door.
Is it great?
Probably not but it works.....

 

[PugetDude]

I went with a 5 ton Trane (Mitsubishi) mini split compressor and a conventional air handler feeding a 14" diameter x 26' long trunk line across the width of my oversize (28 x 36) 4-car garage. Works well in the Phoenix heat.
Pics in my project thread.

 

[Busted_Knuckles]

Years back I had a 3 car garage that I worked in, it was 2x4 R-13 walls, R-19 lid, no windows, insulated door. Put a 18k sleeve unit in the wall, you could hang beef in there, near literally. I LOVED IT.

5k I think would cool over time into youre 75 degree window and also reduce humidity allot making it feel allot better or cooler.

But for another $150, why in the world, would you even consider shorting yourself like that ? Is money really that tight ?

Here's a tip if money is tight, buy used, also folks dont like the 240v " big " units, I bought mine at an estate auction, I paid $1 for it. No one, would put a bid on it, but me, for no other reason, than they could not " plug it in ".

Where also coming into the time of year these go on sale and used prices also fall on them. Nothing better than buying stuff out of season, if your cheap or moneys tight.