Anyone a/c their garage?

[Olmand]

We have a 3 car attached garage with 3 west facing windows. The garage gets 100 in the summer pretty often - at least I think since I haven't measured it yet. I work some from home and am home most nights so the car spends a lot of time in there.

I have an efficient a/c https://under-the-open-sky.com/best-thermoelectric-coolers/ unit with plenty of capacity (too much). I am going to an electric rate of $.05 off peak. I paid $350 combined for July,Aug, Sept for all electric at $.10 a kwh. The garage is pretty well sealed but not insulated (although 50% of the walls are against the conditioned house). The garage is roughly 20% of the volume of the house. I would predict $30 a year to run the a/c in the garage at night.

So isn't it worth $30 a year to protect my new $10k battery (obviously a guess on price)?

Seems incredibly wasteful from an energy standpoint. I can't tint or block the windows but they have blinds.

 

[Midwayman]

$10k battery? Solar installation?

If its really mostly a greenhouse effect I would look into a temp controlled fan similar to what you see for attic installs. That's the same basic problem.

 

[herm0016]

heat rejecting tint on the windows, and shades. its going to cost more than 30 dollars a year to A/C your garage. where do you live?

 

[ISAslot]

I certainly wouldn't put my garage on the same system as the house. Mixing garage fumes with house air is bad idea.

 

[LurchFrinky]

I certainly wouldn't put my garage on the same system as the house. Mixing garage fumes with house air is bad idea.

This.

You could put in a window A/C or something, but connecting your house A/C to the garage would definitely violate code.

 

[zinfamous]

yeah window AC or a smallish single-unit minisplit will do the trick. I see a lot of people opting for the minisplit for their garage.

 

[BarkingGhostar]

In Atlanta, a Mitsubishi split/ductless system is as expensive to get installed as a 2-2.5 ton AC or heat pump. It is so ludicrous that I chose not to bother. If in a planned community the presence of a window AC may be against the covenants.

 

[WhiteNoise]

I installed an extra-large AC unit in my garage wall. My garage is the size of a 3 car garage but only one bay. Years ago I insulated the walls and garage door, dry-walled it and turned it into a home theater room/gaming room. Everyone calls it my man cave but I don't as my kids are back here as much or more than me.

Here in so cal during the worst summer months, our electric bill is around $600 a month. Between the central air for the house and the garage, the AC gets used a lot. But when it's 110 degrees out...it is needed.

 

[bruceb]

I have the same issue here in Apex, NC ... The garage is extremely hot in the Spring / Summer ... And it faces west as well, also a 3 car garage.

 

[zinfamous]

In Atlanta, a Mitsubishi split/ductless system is as expensive to get installed as a 2-2.5 ton AC or heat pump. It is so ludicrous that I chose not to bother. If in a planned community the presence of a window AC may be against the covenants.

a single-unit split system should be relatively easy to install without paying for the service, and you can buy a properly-sized system, just for a garage, for ~$2k on Amazon, I think. Probably less?

Mitsubishi is also very expensive. I quoted out 2 different systems from 2 installers last year for a 3-4 (optional) room system for my house last year. The Carrier system from one guy came in at $13k, and the Mitsubishi quoted at $24k, lol. I honestly didn't know what to believe at that point, so I just decided to shelf it for another season or two. ...and we just went through the hottest summer here, and I somehow made through it with barely any AC whatsoever in the main floor of my house (I had tossed the giant, old, legionaires-incubator AC unit out of my dining room window last fall)....this basically cooled all I needed for most of the floor, which stays ~OK anyway for most of the year. ...I still have the window unit in the attic bedroom, though. It's instant death up there in July-September without it.

 

[herm0016]

a single-unit split system should be relatively easy to install without paying for the service, and you can buy a properly-sized system, just for a garage, for ~$2k on Amazon, I think. Probably less?

Mitsubishi is also very expensive. I quoted out 2 different systems from 2 installers last year for a 3-4 (optional) room system for my house last year. The Carrier system from one guy came in at $13k, and the Mitsubishi quoted at $24k, lol. I honestly didn't know what to believe at that point, so I just decided to shelf it for another season or two. ...and we just went through the hottest summer here, and I somehow made through it with barely any AC whatsoever in the main floor of my house (I had tossed the giant, old, legionaires-incubator AC unit out of my dining room window last fall)....this basically cooled all I needed for most of the floor, which stays ~OK anyway for most of the year. ...I still have the window unit in the attic bedroom, though. It's instant death up there in July-September without it.

probably more the installer. we got a 3 head mitsu hyper heat system installed for 11k. another quote we got for the same system was over 20k.

 

[MtnMan]

Fan to blow the hot air out on gable end or in a wall?

 

[zinfamous]

probably more the installer. we got a 3 head mitsu hyper heat system installed for 11k. another quote we got for the same system was over 20k.

Yes, there is only one Mitsu installer in my area, apparently, so it doesn't surprise me.

I did find that option ridiculous and I was unwilling to pay ~$300 per month on 0% interest for the system because I determined that I couldn't afford it at the time. ...so what I did about 8 months later, is I bought a $30k car. ...lol.

 

[Scarpozzi]

What does your ceiling/roof/attic space look like in there?

In the Winter, you are going to lose more heat through the ceiling (because heat rises) and in the Summer, you're going to get more radiant heat through your roof than anywhere. I recommend doing some kind of insulation overhead...if you've got exposed rafters, you could look at radiant barrier (foil sheets)....or even sheets of foam insulation cut to fit the underside of your roof with the foil side facing up. That alone will help block a lot of the heat from overhead. Consider gable vents and a small fan system or cutting ridge vents if you don't get a lot of sideways rain in your area.

Gonna have to insulate the ceiling at a minimum. Consider planting trees / tall bushes outside the windows to help block the Sun in the late afternoon.

 

[EXCellR8]

Our garage is 2-level, office upstairs is air-conditioned but actual bays are not. In the summer it stays cool enough below that there's no need for serious climate control.

The house was built in the 80's though so the wiring would need to be redone anyway, as it's only 15 amp or something like that.

 

[Zorba]

yeah window AC or a smallish single-unit minisplit will do the trick. I see a lot of people opting for the minisplit for their garage.

I've recently started considering this option my self. I really don't mind the heat in the summer but would love to have heat in the winter. I think I'd add some ceiling insulation at the same time.

 

[herm0016]

i insulated my garage door and it made a HUGE difference. just used 1 in polyiso sheets cut to slide into the panels, and adjusted weatherstriping so it was sealing better. i bet its 20 degrees warmer in the garage when its below freezing outside.

 

[skyking]

I've done two Pioneer Mini-splits this year and they have been about a grand each for a 12K BTU super efficient model. They are not rocket science to install, and come pre-charged for up to 25' line set. I purchased a gauge set and vac pump for less than $200.

 

[jlee]

I've done two Pioneer Mini-splits this year and they have been about a grand each for a 12K BTU super efficient model. They are not rocket science to install, and come pre-charged for up to 25' line set. I purchased a gauge set and vac pump for less than $200.

How much space are you cooling with them? My detached garage is approx 21x25x9 (insulated) and I want to put a mini split in, considering going with 18k BTU.

 

[skyking]

I am heating ~1300 sq ft. One of the 12K units cooled it OK, but we only see mid-80's most summers.

 

[jlee]

I am heating ~1300 sq ft. One of the 12K units cooled it OK, but we only see mid-80's most summers.

I'm doing ~525 sq ft but have higher temps...maybe a single 12 would be ok?

 

[skyking]

I think you'd be Ok if you maintained a decent temp when you are not there. It might not have enough tonnage to drag the space down from +30 in a hurry.
Say, keep it at 75 when you are away.

 

[jlee]

I think you'd be Ok if you maintained a decent temp when you are not there. It might not have enough tonnage to drag the space down from +30 in a hurry.
Say, keep it at 75 when you are away.

Maybe preferable to go to an 18k unit, then. The cost difference isn't much.

 

[skyking]

It's about the wiring. I happened to have a couple of spare 20 amp 120V circuits handy. The 18K units require 240V

 

[jlee]

It's about the wiring. I happened to have a couple of spare 20 amp 120V circuits handy. The 18K units require 240V

Ahh ok. My sub panel is just about where I would want to install my mini split, so wiring will be trivial and I can do either 120v or 240v.