How well do portable air conditioners work in an attached two car garage (360 – 400 sq. ft.)? Due to deed restrictions I can’t use a window unit so I’m considering buying a portable one (12,000 BTU) for working in the hottest parts of the Summer in Houston. It doesn’t need to be icy cold but I would like to reduce the “sweat factor” while working in the shop during the peak heating months. I would appreciate any info folks could provide if they own one and what brands are good.
Thanks for the feedback
Replies
It all depends on the degree of insulation in the garage. If the garage walls and ceiling are well insulated, and you also have an insulated garage door, it will work fine.
I previously had a well-insulated garage, and I now have an uninsulated garage. I was considering insulating the garage (it was uncomfortable in the summer, and unbearable during the winter), but recently got an opportunity to move the shop into an existing insulated space, so I did that instead.
-Steve
Where will this portable unit dump the heat it extracts from the air in the garage?
I believe the exhaust hose will be put into a vent fitted for the window that I can remove when I'm not using the unit. The window vent would be visible only a few hours in the evening but removed the rest of the time so that would be okay.
OK, thanks. I just wasn't sure how these portable units worked.
Glad you mentioned Houston. I too have a garage shop in Houston that is attached to the house. We ran an AC duct over to it with a separate zone thermostat. I insulated the West facing garage door with Styrofoam, and the roof with foil faced Styrofoam. The inside is 10 degrees cooler than the outside. Then I took a iron wood plane from inside the cool house outside. MAN, then it hit me. Do I really want all my equipment to condense moisture and rust up like this plane just did??? Needless to say I have not turned on the AC in there for just that reason. Keep in mind, the humidity gets up into the 90% range during the summer. To modify the "sweat factor" I have a bunch of fans blowing on me all the time. The best one is an old squirrel cage I got out of an apartment house being demolished. (That thing I can set outside the door in the yard.) And of course, I wear the standard Houston summer uniform, shorts, cotton 'CT' shirt and bandana sweat band under the heavy felt 10 gallon hat. (Just kidding about the hat)
To manage the "sweat factor" for the machines, I just let them, and the shop, stay "hot". When we get a sudden change from cool dry to moist warm, I need to keep all the doors closed until the shop warms up.
I have insulated the garage ceiling (enclosed with dry wall) and the door is metal so I will need to put some put foam panels on it for insulation. I hadn't anticipated getting condensation from the temperature difference - I would really just like to reduce the room temp by a few degrees on those really hot days. I have a big shop fan that I use now but of course that is only good while you're standing in front of it.
Thanks for the feedback
In most areas, building codes do not allow opening a duct from the house heating or cooling into a garage. At least potentially, garages have flammable materials and toxic gases that shouldn't be able to move into the house.
I cool my attached shop with a through the wall A/C unit and it works well, but I'm in CT (near the shore). My garage is well insulated--6" foam in walls and 12" in ceilings. Insulated doors too. The A/C takes out enough humidity that I haven't had a rust problem. But of course I'm not in Houston.
Edited 4/28/2009 10:05 pm ET by SteveSchoene
I also live in humid Houston. I have a dehumidifier which I run at nite. I also have a window unit which I run when the tempt is unbearable. I don' have the condensation when I ake the tools outside. I recently put in a blower I scraped from an a/c installation and put it thru the wall. I can blow out dust if it is too bad. Occasionly we will have a low humidity day, and I will open the door and turn on the fan. Lot of trouble but our winters are mild. Good luck M.G.
I'm in Florida and I just moved from Colorado. I installed a separate air conditioner for the garage and insulated the roof and the garage doors (the walls are cinder block). It works very well, but it wasn't cheap. At least I can work out there without sweating all over my tools and projects.
The roll around air conditioners create a lot of water at they cool and that must go somewhere. Folks I know that use those types of air conditioners leave the garage door open to drain the water, but that eliminates the benefit of cooling. Tough situation. Good luck!
Tim
Have you thought about a mini-split? Sanyo makes a nice unit. You're gonna get real familiar with how to change a filter tho', no matter what you choose. ;-)
Mike Hennessy
Pittsburgh, PA
Here's a write-up about my experience installing a 12,000BTU portable A/C in my shop: http://ncwoodworker.net/forums/f81/big-workshop-gloat-8868/
Isulation is very important and having a dual hose unit really makes a difference. Keeps the cool air in the shop and uses outside air to cool the condenser. The unit I have also has a pump which sprays condensed water over the coils. This increases efficiency, evaporates the condensed water and exhausts it to the outside. Rarely have more than a few tablespoons of drainage/day.
What is a mini-split and how does that compare with a portable unit? My attached garage windows face the street (can't install a window unit that will show from the street) and I have a brick wall on one side and the metal garage door on the other so I don't have a good place to install a wall unit.
A mini-split is kind of a hybrid between a window AC unit and a whole house system. It has a condenser that sits outside and a air handler that mounts on the wall inside. Just like a whole house system, there are hi and low pressure lines between the two. You can get cool only, or heat/cool units. Here's a page, if the link works:
http://www.minisplitsystems.com/cgi/display.cgi?item_num=12KHS71&gclid=CLby4Py0k5oCFRLoxgodsWS0NQ
Mike HennessyPittsburgh, PA
Mitsubishi also makes "split" units: http://www.mrslim.com/Products/Category.asp?ProductCategoryID=24.Many communities allow these types of units as the outside part sits at ground level and can be easily shielded from view.Howie.........
I live in South Florida and worked (sweated) in my garage until I installed a window air conditioner. My community doesn't allow window air conditioners either, so I built a shelf inside the garage under the window and the unit sits on that. I can tell you that it lowers the temperature and humidity to comfortable levels even during the hottest summer weather. I haven't had any problems with rusting tools.
Jim
Sounds great - can you post a pic of the setup? I'm not clear on how the hot air is vented if the unit is on a special shelf below the window.
Thanks
Jim,
Where does the hot exhaust air go if the unit sits on a shelf beneath the window? Please send a pic
Thanks,
Brian
I'm not Jim but here's how my portable A/C is installed in my attached garage shop with no operable windows:
http://ncwoodworker.net/forums/f81/big-workshop-gloat-8868/?highlight=gloat
This dual hose unit works very well. I have since improved the shop insulation. The second hose pulls in outside air to cool the condenser coils. Single hose models use cooled air from the inside to cool the condenser and then exhausts it outside.
My unit removes a large amount of humidity by pumping condensate over the hot condenser coils. This evaporates the condensate and exhausts it outside. I have only seen about a tablespoon max of condensate in the drainage hose and that was during a tropical storm with an 80 degree dewpoint!
Tarhead,
What size unit is this and what size is your shop? I've read a lot of negative feedback on the portable units recently so either folks aren't installing them and running them correctly or they are undersized for their shop. This seems to be the best solution for my situation but I can't find a good review on a unit at reasonable cost.
Thanks
Hi there!
My shop is an attached 2 car garage w/10ft ceilings. The unit is a 12,000 BTU Amana. I've blown in cellulose insulation into the stud cavities in the one long exterior wall and the ceiling. The overhead door has 1" of foilfaced polystyrene insulation attached to it with hotmelt glue in the corners.
The key for me was getting a dual hose unit. The single hose units use the cooled inside air to cool the condenser and this results in warm/ humid outside air being pulled in to the shop to make up the difference. This results in a very inefficient system with lots of condensation and reduced cooling. Another good thing with some of the newer units is a pump for the condensate which sprays the condensate over the condenser and evaporates it out the exhaust. As I posted, condensate drainage is not a problem...even during a tropical storm with record dewpoints.
Unfortunately I don't see a 12k btu unit these days for $350 but I will have to keep shopping. Thanks for all the background info on your setup - looks really good from the pics.
Not sure where you live but I got mine here:
http://shop.bjs.com/-399-99-less--70-Online-Instant-Coupon-on-Amana-12-000-BTU-Portable-Air-Conditioner-Air-Conditioning---Cooling_stcVVproductId40182377VVcatId428469VVviewprod.htm
Thanks! I looked back on your previous post and was curious if you have an overhead/garage door in your shop, and if so how did you seal the edges and top?
I do have an overhead door. The edges seal up pretty well without any weatherstripping. There is weatherstripping attached to the building for the top. The bottom is sealed with heavy weatherstripping attached to the bottom of the door.
Tarhead,
Thanks for the link - I was able to buy the same Amana unit and tried it out yesterday. I had to add some of the aluminum-backed foam panels to my garage door and weatherstripping to reduce the air leakage before turning it on. It seems to cool pretty well, but I got about a 1/2 cup water from the tank after about 1.5 hours of cooling. I also wrapped the exhaust hose as you mentioned and that really reduced the heat lost from the hose. I'm using the window kit because I don't have a good way to route the hose exhaust through the wall, but that works okay.
Thanks for posting the info and sharing advice about the setup!
Brian
Brian,
I'll take a picture this afternoon and post it tomorrow. I removed the window from the frame and the A/C unit vents out the window. I used a piece of plywood to fill up the space around the unit. Jim
I had just finished sanding and didn't vacuum the front of the unit, but this should give you an idea of how I did it. The unit vents through the window and I put a hole in the shelf so that the water can drain into a bucket below.Jim
Ok now I understand - thanks for posting the pics; how often do you have to empty the drain bucket?
I drain the bucket at the end of the day. Once is usually enough except on the most humid days. I'll have to check on the garage size and BTUs and get back to you tomorrow.Jim
Jim,
Forgot to ask - what is the size of your garage shop that you are cooling and what BTU is your a/c unit? I'm seeing that the window units provide more cooling with less BTU.
Thanks
Jim,
From the pics it looks like a portion of the unit's exhaust is venting back into your shop. When you use the a/c unit do you slide the unit out further out the window then pull it back after use for storage?
No, it doesn't vent into the garage, just out the window. The unit stays where it is...screwed to the wooden shelf. I know that I said I would measure the garage and see what the BTUs were on my unit, but I when I get into the shop I just start working and forget. I'll make a note to do it today and get back to you. I remember that I calculated the square feet of the garage when I bought the unit and checked to see how much cooling capacity I needed. As it turned out, the unit I bought had almost twice the capacity needed, but I figured that there would be leakage with the garage door. I only spent around $400 for the unit, which was $100 more than the smaller one, but it had more features as well as more power. It has a remote control like a TV, so I can turn it on and make any adjustments without having to leave the workbench. I'll check it out and get back to you.Jim
I can't tell from the pic but from the front it seems that some of the exhaust vent is still venting into the garage - maybe your walls are thick? Would you please also tell me the total depth of the unit and the depth that is in the garage up to the window? The units that I have seen for sale are pretty deep so I could build the shelf as you've done but it seems a lot of the unit would still be exhausting hot air into the garage.
The walls are cinderblock. I'll take some close up photos tonight and post them tomorrow.Jim
OK, I just took some measurements and the garage is about 400 sq. ft. The unit I bought is a Frigidaire #FAM186R2A and it has 18,500 BTUs. There are vents on both side of the unit (see picture), but I think they're intakes, not exhaust vents. I don't feel any hot air coming out of them. Anyway, the unit can get the shop into the high 70s during the summer. Hope this helps.
Jim
Great - thanks for posting the updated pic and for the measurements. According to that square footage, the unit should be about 10,000 but for 400 sq. ft, so would you say this is the proper size unit for your shop?
Although 10,000 BTUs may be the recommendation for 400 sq. ft., I am very glad that I went with the unit I bought, which has 18,500 BTUs. A garage has a lot more leakage around the door than you would expect to find in a house and I felt that for a relatively small investment it was worth it to have the additional cooling capacity. I can work comfortably during the hottest days of summer, which was the whole point of getting the unit in the first place. Jim
I live west of you..AZ to be exact so heat is no stranger. My garage can reach 133 if the house AC is off! it's a dry heat but yours is very very humid so my unit might be the thing for you as it blows dry cool air. I have no windows but a homeowner's assoc as well. I solved my issue by getting a small portable "window" unit that sits outside my garage door on a rolling cart when I am working and delivers the air through a sqaure opening in my side door. I use a heavy 3/4 ply slider to seal the door when I am not using the unit. This assures security as well. Crude but effective! I may be benefitting from the cooling the attached garage gets from the house but I no longer have to dial up the inside thermostat to get the garage cooled! $$$$$$ it works for me. Like you I was looking for a few degrees less and this did it and then some.
I'm located in Orlando and installed a Haier 12,000 BTU potable A/C unit (HPRD12XC5) in my 2 car attached garage/shop. This required adding two 5" holes to the concrete block wall, a job similar to adding two dryer vents. The condensation line is a clear plastic hose that runs along the floor to the door where it drains. The garage door is an aluminum overhead type which I've insulated by cutting sheets of 1" thick 4'x8' styrofoam into rectangles that press into the door segments, quite a job in itself. A new rubber gasket replaced the old one at the door's bottom and additional lip type gaskets added to the door sides to minimize air, and bug, leakage.
After two years the unit has performed flawlessly, but the best it can do on a 90's summer's day is give a 10 degree temp drop. When I plan on working in the garage I give the A/C a head start by turning it on first thing in the morning. The next step will be to add a skin of aluminum over the styrofoam because it's a nasty fire hazard having it exposed in a vertical orientation and it's sensitive to gouging from errant planks. Following that I'm going to frame in, and add fiberglass insulation to, the two walls with an outside exposure. While insulating the walls some badly needed electrical outlets will be added before covering them. An extra doorbell will also be added in the garage, the house doorbell cannot be heard from the shop when power tools are running. At some time a powered vent, like that for a bathroom, will be added. With the garage buttoned up for A/C any fumes from paint or glue get overwhelming pretty fast.
Consider doing the entire job in a single year and recording all costs for a tax credit.
have you experienced any problems with tools rusting from this setup? I've seen that some units have dehumidifiers that don't require a water fill. Also, I've seen aluminized foam sheeting at the big box stores so could this provide enough insulation and radiant heat relief/rejection in the panels of the garage door (metal door is not insulated).
Someone else a few posts back noted that the portable unit worked very well for cooling, so do you think the maximum 10 degree heat relief for peak times is due to the humidity or lack of insulated space in the garage? BTW, I have R-20 insulation in the ceiling and no insulation on the two exterior walls in the garage so I'm expecting some losses.
Due to the high humidity in Orlando rust is a constant problem with any steel or iron exposed to outside air. A/C in the shop helps control this problem by dehudifying the air and by eliminating the sweat that drips from me onto the tools. The A/c is run only when I'm using the shop to keep costs down, but when the A/C is turned off the temp increase is slow enough that condensation of humidity on tools is no worse than it was before the A/C.
I didn't use the aluminized styrofoam because I used the hot wire method for cutting the panels, I thought the aluminum foil would jam things up so I stayed clear of it. Plain styrofoam was a tremendous improvement in heat loss through the door, I doubt that aluminized foam would improve it any. The door itself is aluminum and stops most radiant heat entry. The door has a southern exposure and at mid-day the door was too hot to touch, now it's cool and no heat can be felt coming through at all.
The big surprize for me was the rate that heat penetrates a bare block wall. It'll be a lot of work to insulate them, have to do it a stud at a time because the garage door tracks prevent the normal build it on the floor and roll it against the wall method. It'll be worth it in energy saved and comfort gained.
A seam-sealed, 1"-thick layer of styrofoam on the block wall will do wonders.
-Steve
bmyyou,
If your shop is insulated you can figure 1 ton of a/c per 300 sqft. The small portable units can be a bit of a pain. Some have to be vented outside, others have a condensation tank that has to be emptied all the time.
If you can hide the outdoor unit company's like Sanyo make units that don't need all the duct work or a air handler. I have installed a lot of these systems in area's that require low noise and visability.
Taigert
I open my shop doors and have a Mosquito Net!
I just leave the doors open and have miskieto netting..
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