Air conditioning advice for garage workshop

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Forum topic by Vrtigo1 posted 08-10-2010 06:16 PM 14006 views 0 times favorited 9 replies Add to Favorites Watch
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434 posts in 3168 days

08-10-2010 06:16 PM

Not sure what category this should go in, so I figured the lounge is a good place to start. I read over some of the other posts regarding A/C’ing a workshop but still have some questions.

I live in Florida, and in the summer the temps are usually in the mid to high 90s, which makes working in the garage less than pleasant. For the past few months, if I spend more than 30 minutes or so in my garage, when I go back into the house, I’m dripping with sweat and have to take a shower before I can do anything else.

My house is block, and my garage doesn’t have any windows. The garage has two exterior walls, a block wall which faces north and the garage door which faces east. The north wall doesn’t get much direct sun, but the garage door does, although strangely enough, the door feels relatively cool to the touch even in direct sunlight, and I don’t feel much if any heat coming off of it.

Above the garage there’s an attic. There’s no insulation between the garage and the attic, and it’s not feasible for me to add it at this point because I’ve already put down a particleboard floor in the attic for storage.

I picked up a 12,000 btu portable A/C unit for $100 on Craigslist and currently have it ducted outside via a dryer vent. It helps, but it’s still noticeably warm in the garage.

At this point, I’m trying to determine what the best option would be to get the garage cooled down to a more comfortable temp. I could either run some vents to the garage from the central A/C in the house, or I was also considering installing a mini split A/C system just for the garage. I’m hoping to keep the cost under $1,000, and I want to do whatever will end up impacting my light bill the least.

I have an A/C guy coming out tomorrow to give me some recommendations, but was hoping to get some advice so I can ask him the right questions.

9 replies so far

View Dan's profile


3630 posts in 3057 days

#1 posted 08-10-2010 06:38 PM

I think if the garage was well insulated it would hold the air a lot better. You can insulate the attic floor for a lot less then 1000 dollars. I would also insulate the walls in the garage. I had the exact same problem in my garage. I put in an air conditioner and it didn’t work all that well. I then insulated the garage really good and it made a huge difference. If its not insulated well enough then your loosing a lot of the air.

-- Dan - "Collector of Hand Planes"

View wseand's profile


2796 posts in 3219 days

#2 posted 08-10-2010 06:50 PM

If it isn’t properly insulated it is going to be quite difficult to keep it as cool as you are looking for. If your door isn’t sealed nice and tight your air is just going to release all that cold air. You could spend thousands of $$$ on the AC but never get the results til its insulated and seal properly. You could try adding a vent from the house in addition to the portable one you have now this may help. You might want to add a fan to push the air around. They also sell wall mounted AC units that seem to help out quite a bit, although I have never used one.

View wseand's profile


2796 posts in 3219 days

#3 posted 08-10-2010 06:50 PM

This was a duplicate sorry.

View DrDirt's profile


4492 posts in 3919 days

#4 posted 08-10-2010 10:53 PM

If this were a place I plan to keep, so not looking to do any ‘Rube Goldberg’ kind of solution:
1) don’t tie into the house AC – - – that’s a no-no, code doesn’t like the idea that even if the door was open, exhaust would enter the house.

I see 1 temp and 2 permanent solutions.
For permanent:
I would put in a window – and use a window unit when needed. You’ll probably apprecieate some natural light anyway.

If you still are going to cut in, but don’t want anybody looking in the windows I would install a wall unit. The same thing that is in all the holiday inn’s. It is sealed/insulated well and can also serve as a heater when needed. This should be easy with a block wall. But even though you can find these units used from hotel renovations, the whole operation would be more than a grand unless you do the demo yourself.

If It is just a matter of a couple months of the year it is too hot…(NEVER too cold), I would look at a replacement garage door panel, or simply a spacer the height of a good window unit that you can set on the ground and lower the garage door on top, but still closing off the bottom.

Good luck

-- “The two most important days in your life are the day you are born and the day you find out why.” Mark Twain

View Steve Peterson's profile

Steve Peterson

392 posts in 3259 days

#5 posted 08-11-2010 02:50 AM

It sounds like you are loosing “cool” as fast as your air conditioner is generating it. The best thing to do is add insulation.

Can you blow insulation between the ceiling and the particle board floor in the attic? The big box stores in my area loan out a celulose insulation blower for free (refundable security deposit) with the purchase of a certain amount of insulation. You might only have to lift one row of particle board.

I have a garage workshop that luckily has wall insulation behind the sheetrock. Ceiling insulation helped a lot, but it was still a bit much for my 14000 BTU portable AC. Insulating the door with 1.5” styrofoam panels was the answer. I bought 4×8 sheets because the pre-cut kits were the wrong size. The springs needed to be adjusted afterwards even though it seemed like only a few pounds of styrofoam was added.

-- Steve

View Vrtigo1's profile


434 posts in 3168 days

#6 posted 08-11-2010 05:31 PM

Thanks for the suggestions. A window unit is definitely out due to HOA rules. Next time I go to the borg, I’ll take a look at the foil insulation panels. I assume that’s what I’d want to put on the garage door.

View Eric_S's profile


1565 posts in 3372 days

#7 posted 08-11-2010 05:43 PM

Wseand, thanks for the link. I didn’t know I could get a wall mounted ac/heat pump that doesn’t require an exterior vent. :) THANK YOU!!!!! Now if only I could afford that in addition to the lathe/lathe tools/scroll saw/drill press I’m wanting. lol I think I’ll wait till next year to buy this wall unit but again, thanks :)

Vrtigo I’m in the same situation as you, although I live in Indiana so I don’t have too many high 90’s days (maybe 1-2 months). I spent around $250 insulating the walls and ceiling above the garage (you can write this off as enegry efficiency). This helped tremendously in the winter and summer, although it can still get pretty warm in there. The seals around the garage door had some air gaps too so I added foam insulation strips to try and block those gaps. A couple pieces will come loose when opening and closing the door but for the most part they have helped a great deal. When I close the door and turn the lights off, I don’t see any light coming through cracks anymore :) The garage door itself is solid wood, so I don’t know if adding foam panels on top would help much. The biggest issues I have with those doors is the expansion/contraction of them causing gaps to open back up or close.

I have two fans circulating air around the room. One oscillating fan on one side of the garage, and a box fan with air filter on the other side. The addition of the oscillating fan made a big difference over just the box filtered fan and is doable except on the rare 95+ days near me. I have been tempted to add a vent from the furnace(on the other side of garage/house wall) but that would require a return as well which means bringing in sawdust and exhaust fumes occasionally which I dont think would be a good idea. I am not about to demo the side of the garage either to add a window/wall a/c unit but I’m still looking for other options. I guess its just something for me to keep in mind for our next house (SHOP MUST HAVE WINDOWS AND access to AC/Furnace)

-- - Eric Noblesville, IN

View Goran's profile


1 post in 1385 days

#8 posted 02-03-2015 11:53 PM

Air conditioning service should always be performed by experienced and trained professionals. It is cost effective, guarantees safe use of the unit, doesn’t create extra expenses or injuries, and more importantly, doesn’t waste your time and energy.

View Steve Peterson's profile

Steve Peterson

392 posts in 3259 days

#9 posted 02-04-2015 12:46 AM

I realize this is an old thread, but will add my comments anyway. Two things about your original post are concerning.

Insulation should always be your first priority. It is easier to keep a room cool than it is to compete against the sun beating down on you. I had an un-insulated garage door that made a huge difference after it was insulated.

Also, are you sure you trust the efficiency of your $100 CL air conditioner? Maybe there is a reason that it was so cheap.

-- Steve

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