A/C for the shop

[DynoDave]

One of the last details I want to put into my garage plan is a window air conditioner. I'm not going to actually put it in a window, but want to frame an opening for one in advance. That means I need to know the size of unit I will need. Ince I know what ton rating I need, then I can go and measure up an appropriate sized unit, so I'll know what size to make the wall opening.

I've never bought one of these before, and don't know a whole lot about them in particular. My shop will be 926 sq. ft., with 10 foot and 12 foot ceiling heights, 3 overhead doors, and insulated/drywalled.

Is there anything in particular I should look for in a unit? Any recomendations/tips are appreciated. Any thoughts on framing it? I was just thinking of framing it like a window, and dealing with trimming it inside and out when the time came.

 

[TOMWELDS]

If you are using a "window" unit, make sure the wall or sleeve you make doesnt cover the side vents on the A/C unit. If it will, you will have to get a "sleeve" unit and they cost considerably more. Did you check out those Mitsubishi units that have a seperate compressor? It could save on installation problems.

 

[kartracer55]

Check out MSC for the brand fedders. Dont know anything about the brand, but they have HUGE wall units that run on 220 that both heat and cool.

Worth a look.

Jim

 

[Wile1Coyote]

Dave not sure if it helps any but pep boys has been advertising some portable ac units. not sure how they vent but it may be worth looking into as the btu ratings seemed to be higher than the window units I have seen. Prices around $400. There is a pep store at Van **** and 17 if you want to check on lunch. Hope it helps.

 

[bmwpower]

The Pep Boys unit vents using a dryer type vent off of the back. Not sure how it vents, either through a window or ?

 

[jstbecauz]

Why not put in central air? It will be much more efficient. I just had my HVAC guy in here and he was going to install a 3 ton unit in my shop. $600.00 installed for a used system still carrying 1 year left on its warranty.

 

[bmwpower]

Good thing about central air is you already have the air handler and the duct work... now you just add a furnace for the winter

I went with a separate gas heat/air unit in my garage. Definitely a lot more money to install. Plus, you need to work it into your space since it's not as small as a window unit.

 

[rcroob]

Just installed a furnace and central air in my garage, I recomend it, it does cost more up front but its more efficient to run and more even cooling and heat.I put the furnace upstairs, you can even mount it in the rafters if you get a horizontal downdraft system.

 

[DaveL.]

I use a 18,000 btu unit to cool my 1200 sq ft garage. My Dad donated the 5 year old conditioner when he was having central air installed at his house. It just so happens my new home/garage was being framed at that time. I gave the framers the AC case dimensions and they framed it out for me (see picture). I was installing a 220 line in the vicinity of the AC unit so that was taken care of. The company who installed Dads central air brought the unit over to my house checked it out and mounted for me. It gets the garage plenty cold in about 3 hours. I turn it down to the lowest cooling setting and it keeps it about 70 degrees....plenty cool!

Dave

 

[bdaz442]

I'm installing a 28,000 btu unit in my shop tomorrow. Just like you did I'm framing out a hole about a foot off the ground in a corner , completely out of the way.

 

[DynoDave]

Thanks for all the replies. DaveL is showing the type of install I had envisioned.

But I do have my house's old furnace that I saved to heat the garage with. Adding a used central air unit on to it is certainly a tempting notion. I'll have to talk to my installer, and see what he might have laying around.

 

[krooser]

I have a 35 year old Fedders that I got free from my father-in-law...about 12,000 btu's...cools my 1500 sq. ft. shop nicely in 90 degree heat....

 

[86turbodsl]

Why not put in central air? It will be much more efficient. I just had my HVAC guy in here and he was going to install a 3 ton unit in my shop. $600.00 installed for a used system still carrying 1 year left on its warranty.

That's a killer deal. I just installed a 2 ton unit myself in my home, and even with a FREE condenser unit, the install cost me about $500. And that's doing it all myself. $600 to have one put in is CHEAP CHEAP CHEAP.

 

[AV8OR]

A suggestion; oversize the opening by a few extra inches then trim around it. In ten years when your current unit blows up and you can’t find one the same size you’ll be glad you added those inches. Also the last unit I installed required a five-degree slant to the rear so it could drain properly. This too will require you to have a taller opening than the exact size of the case.

The units with the compressor outside and the fan inside are called ductless air conditioners or mini-splits.

 

[REFLEXX]

Hello all.

I'm in the process of building my "Garage-Mahal" and decided to go with "in the wall" window AC units. I've got 1,450 sq ft divided into four rooms. 750 sqft "fab" room, 500 sqft "machining" room, 260 sqft office & 240 sqft storage. Here's what & why:

1. Central A/C would have cost about $3,000 to $5,000 installed. Three window AC units = $1,000 total.

2. Where do I put the thermostat? One room freezes, while another boils unless I keep all doors open and cool the entire thing. Then the dirt propogates from room to room and I cool the whole shop every time.

3. Every room except storage gets an independent AC unit and the thermostat is right there. If I'm not doing work in the fab room, I don't cool it!

4. Fab room gets a 25,000 BTU unit. Milling gets a 12,000 BTU and office gets 8,000 BTU. I know its not good to oversize ( too much BTU per sqft). But I will have many heat generating sources and I want to STAY COOL.

5. The brand I'm using is LG and I bought them from Home Depot. They are consumer reports rated some of the best and have a great warranty.

6. I one unit craps out in five years, I replace it with a better one for a few hundered dollars. That's cheaper than just one HVAC repair call!

7. Each one will have it's own wall opening, a few inches bigger than necessary then insulated around. This way if the replacement is a different size, I'll be ready.

8. Vent fan with shutter in the fab room, at the highest point. To **** out all the heat and fumes from welding / farting / burping /etc...

9. I will add radiant heaters for those rare cold days. I'm in So. Cal. we get those once in a while. I will have them turn on 1/2 hour before I arrive and aim them toward the concrete. Then the concrete will radiate heat all day! Again, only in the rooms I'll use that day.

10. I will have R30 insulation in the ceiling and R19 inthe walls. Drywall is 5/8"


and you thought I was kidding about the "Garage-Mahal" part?



How's that for a first post?

REFLEXX

PS- nice forum, I'll stick around!

 

[DynoDave]

Thanks for the tips on oversizing the opening guys. I hadn't thought about the unit needing a slight angle to drain properly.

 

[smooth72]

I just bought a GE 23500btu AC window unit at SAMs for $349. Just in case anybody else was looking for one. I plan on mounting it in the wall and one thing nice is the air vents are only about half way up the outside box. I plan to mount the unit so that outside it starts at the vents, I hope. The garage is fully insulated, 1400 sg ft with a 12ft ceiling.

 

[krooser]

I've got a 35 year old Fedders that I got FREE from my father-in-law....110V...about 12,000 btu's...cools my 1500 Sq. ft. nicely....10' ceiling...average insulation...keeps it at 68 when the outside temps are in the 90's...

 

[mrl05]

New to the site and first post. Great site

I have a newly constructed house with a 20 X 24 garage and there is a sitting room and closet over part of the garage. The garage has 2 ducts in the back wall from the downstairs furnace to the rooms over the garage. I was told this was to help keep the rooms over the garage warm from the cold air in the winter time. Now, I'd like to tap into these 2 ducts to add registers to have A/C and heat in the garage. How realistic is this and will this severely affect the air balance in the house? I figured since the duct work is already there, this could be an easy solution but figured I get some better advice. In addition, the garage is fully insulated including the attic space in the ceiling.

Any advice would be appreciated.

Thanks,
Mike

 

[04 Navi]

I would seriously consult a pro on this. One of the main reasons is that most municipalities, if not all, would not allow garage air to be mixed with your home air due to CO.

In addition even if you could do this I suspect adding 3800 plus cubic feet of air may tax the BTU's of your existing system.

 

[rickairmedic]

I would seriously consult a pro on this. One of the main reasons is that most municipalities, if not all, would not allow garage air to be mixed with your home air due to CO.

In addition even if you could do this I suspect adding 3800 plus cubic feet of air may tax the BTU's of your existing system.

Ok as to the CO problem that isnt a concern as long as you are only adding supply air to the garage and not taking return air from the garage .However Navi is right on his other thought the extra square footage of your shop might tax your existing system somewhat .What you want to do is feasable and not a dificult task and by all means I would try it buuuuuuuut it would have to be a trial run and if it does tax the system you would have to reseal the ducts and start from scratch on the garage HVAC .


Rick