I'm converting my two car garage into a home theater and was seeking some advice on the cheapest way to heat, cool, and dehumidify the room. Here are some details:

  • Garage was once a model home office so the walls, ceiling, and garage door are insulated.
  • Dimensions are about 20' x 20' x 10'.
  • The garage has no windows.
  • The garage has attic access.
  • I live in Austin, Texas. Temperatures range from triple digits down to occasional freezing.

I'm am most concerned about the cooling and dehumidification. I can use an electric heater if need be to warm the garage during the winter. Since I will have sensitive home theater equipment in the garage, it will be important that the garage remain within a normal room temperature and humidity level. I'm trying to keep the project within $1500 but I'm afraid that may be out of reach...

I have central air and heating in a small 2200 sqft home.

  • 1
    How is the rest of your home heated? Forced air?
    – JNK
    Feb 18, 2012 at 11:58
  • If you register you account it will mean that you'll be able to log in from anywhere and edit your question etc.
    – ChrisF
    Feb 18, 2012 at 14:43
  • I'm assuming the garage is attached. Have you considered having an HVAC pro come and check if your house's existing heat/AC system could accommodate the extra load of the garage? If so, it might be as simple as adding & adjusting ductwork. Feb 18, 2012 at 15:02
  • I'm currently looking into the option but I fear that my HVAC will have insufficient power. Do you know of any alternatives? Feb 18, 2012 at 21:15
  • 1
    You could save money by just leaving it as a garage, mount the video equipment and pretend it's an old-fashioned drive-in movie. :) Feb 19, 2012 at 23:28

3 Answers 3


If your current AC is not adequate to extend to the garage area, then a ductless mini-split wall mounted AC unit is probably ideal for your situation. Once installed, you'll likely exceed the $1500 budget, but I think it's the best of the options. You wall mount half of the unit inside the home and run the cooling lines through the wall and out to an exterior coil. They also have a condensation drain line that you run outside to help with the humidity.

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You can always go with a window AC / Heater or something like this;


If you go this way make sure you size it out to match the room. This one shows that it has a dehumidifier also.

I think you are right about your unit not being able to handle your garage also. They are usually sized for the house. Too large a unit is just as bad as too small a unit. Then you will also need a return air duct.

While ease of use and having everything you need in one unit might be a plus, the cons are going to be the noise when on and the possibility of having to have an extra electrical circuit put in. If your panel is in or outside the garage that will make it a lot easier, the other side of the house will be a chore.

There are lost of style to choose from so choice won't be a problem.

  • Window unit won't be an (affordable) option since OP states there are currently no windows. He'd need to cut a hole in an exterior wall right?
    – JNK
    Feb 19, 2012 at 16:36
  • Actually the unit I picked does not go in the window. My garage in California has 2 vents in the two external walls about a foot off the ground that the hose that goes outside could fit into.
    – lqlarry
    Feb 19, 2012 at 16:41
  • If you store anything in your garage that's combustible I wouldn't seal those vents with an A/C unit. Those are there to convect the fumes out and keep your house from going boom. Ditto if your furnace / hot water heater is in there. If there's ever a CO backup, you could suck those fumes into the house and ......
    – el katz
    Feb 21, 2012 at 1:33
  • Thanks, all electric here, except my car. What do I really know about this? I park cars in my garage.
    – lqlarry
    Feb 21, 2012 at 2:39

When converting my garage to home theater I purchased one of those portable ac units cut about a 5" x 5" square hole installed dryer flap so it closes when ac not on. I eventually had a duct ran to garage to add to house cooling and upgraded my cenral unit from 2.5 ton to a 3.5 ton unit. Cools garage perfect still have portable unit but seldom use. I upgraded to this as i wanted room cool and comfortable at all times. Good luck

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