Has anyone put A/C in their garage?

[VintageGarage]

I have added a spur off of the main A/C system of the house to run cold air to the garage. We live in Houston and heat comes free with every garage down here. You can not work in a garage in Houston in the summer without A/C just to remove the humidity if not to lower the temperature. I had the unit sized with this extra load in mind when it was changed out recently.

I found that I had to also insulate the thin metal garage doors from the direct solar radiation. In the mornings the sun would hit the East facing doors and drive the heat up tremendously. By installing 1/2 rigid insulation panels on the inside of the doors this heat gain was cut down quite a bit.

Has anyone else out there added a duct from their main A/C unit into their garage? Has it achieved the desired results?

 

[Finley]

havent done it yet, but i really want to before the summer months start beating down on me up here...the humidity can be a bear in cincy

 

[Roospike]

You shouldnt duct your home heat / A/C into your gargae as its a fire hazzard to do so. ( let alone smoke, CO ,ect )

If you get a fire in your home your insurance co will be laughing all the way to the bank when they see that in your garage and pull the plug on your insurance check .

Do what you want but just a FYI for you .

 

[Cliff Ramsdell]

Instead of running a duct to garage I added two lines to the compressor and another Furnace/blower/coil unit in the garage, kind of like a van with front and rear A/C units.

This kept the fumes and such from the garage and allowed better temp control as the other setup you would bne a slave to the demands of the house to keep the shop cool.

If the compressor size is big enough to run both you should be good to go.

Cliff Ramsdell

 

[VintageGarage]

Thanks for the information regarding the insurance. Very good to know.

 

[Special55]

The other thing to remember is you won't achieve the desired results without a return air duct. (Another reason you may not want to connect to your house system) If you don't pull the hot humid air out of the garage and run it through the evaporator coil you'll just be pushing cool air on top of the hot humid air. I hope that makes sense

 

[Vicegrip]

Against many codes to connect a garage to a house ventilation system. Big red flag. Also as was said all the air that goes into the garage will have to come from the house and the air will have to be ether returned from the garage or pulled in from outside as your house will go into negative pressure. Please do not add a return to correct this as it will pull garage air into the house. At least get a fire damper that is the size of the duct. They are made to spring shut when they reach a set temp. This will still not stop fumes from getting into the house if the conditions were right.

Look at mini split AC or a through wall window type units. Low end Mini splits can be purchased for $1200 including the line set. Through wall units are inexpensive and some are made to fit between studs 16 on center. You cut a hole in the inside and outside wall, inset the mount, stuff the unit in place, plug it in, done.
Mini splits are not as easy to install but not hard ether as as most come pre-charged. All you need to do is place and hook up power to the outside unit, run the 2 copper lines and one condensate line through the wall, mount the inside unit and hook up the lines and power connector. This is all done through a 3 inch round wall penetration. You need to pull a full vacuum to get all the air out of the lines before you release the pre-charge into the lines and inside unit. Most folks can instal one in less than a full day. You should be able to get an HVAC contractor to finish up with the vacuum pump after you do all the work.
The inside unit gets its power from the outside unit and most come with a remote control so you can mount the inside part near the ceiling and out of the way.

I am adding a 24X30 room the the back of the house and I plan to get 2 mini split heat pumps. One for the new room and one for the shop that is now using a small window unit for cooling. They are very common world wide and well tested devices. Some have 16 SEER ratings and make less sound that a ducted unit even with the blower in the room on the wall.

 

[JohnZ]

My attached garage is 2500 sq. ft. (super-insulated), and I installed a Mitsubishi 42,000-BTU ductless mini-split (A/C only - I already have heat) in the summer of '05; does the job with no problem, hardly makes a sound. Details in the link:

http://www.villagephotos.com/pubbrowse.asp?folder_id=1411059

 

[carguy123]

The concerns about adding house air to the garage are overstated.

Yes, with a return you would **** garage air back into the house which, under certain circumstances, might not be such a good idea but blowing from the house to the garage won't hurt the house air quality one little bit.

You don't need a return because your garage isn't sealed as well as the house and the air you send to the garage will leak out the garage door giving you the air exchange you need to rid yourself of the humidity.

Now as to the negative air pressure in the house, there is some truth to that. Where does the air come from now that cools your house? Is your house new enough to have one of the outside air handlers? If so then you don't have an issue. If you don't then you will get air the old fashioned way, which is from cracks, leaks, doors, windows. In the olden days houses were built "loose" just to allow this.

Prior to the late 60's houses were built to allow about 2 exchanges of air an hour. Even further back it was 4 exchanges so you wouldn't get the "vapors" but back then they ran unvented heaters.

In any case if you sized your new AC to accomodate the garage AND your house is newer and therefore sealed better then the worst thing you would need to do is add an outside air handler. It doesn't duct air in all the time just intermittantly.

I wouldn't worry about it. I'd just do it and see what happens. You'd never have a negative pressure enough to cause door or window probs but if you were worried just crack a small window in the bath and close the vent in the garage when you aren't conditioning the air.

 

[Roospike]

The concerns about adding house air to the garage are overstated.

Yes, with a return you would **** garage air back into the house which, under certain circumstances, might not be such a good idea but blowing from the house to the garage won't hurt the house air quality one little bit.

You don't need a return because your garage isn't sealed as well as the house and the air you send to the garage will leak out the garage door giving you the air exchange you need to rid yourself of the humidity.

Not to be rude , but do you know "how" an A/C system works ?

Just blow the humidity right out the garage door cracks ?!

Com-mon ..........lol .......... You can do better than that. Sounds like a bar story , and were not drunk yet.

 

[Special55]

OK, picture it this way.

When you have the A/C in your car on normal it cools the car down pretty well. Now you turn the A/C to max or hit your recirculation button and you could hang meat in there.

Now when your house system is just blowing air into the garage with no return the A/C is on normal. The problem is your garage is much bigger and the amount of cool air it takes to displace that hot air is considerable larger. The other problem is your house is recirculating the air and will cool down much quicker (max A/C). With the thermostat located in the house the system will shut off way before it is comfortable in the garage.

I woud just get the proper sized window unit and stick it in the window or through the wall. I was able to pick mine up at Home Depot for $139.00 in the fall. It is a 18,000btu A/C unit that normally sells for $350.00. The other advantage is you don't have to listen to the wife complain about the garage smell coming into the house.

Good luck and keep cool

 

[Willy Victor]

Not to be rude , but do you know "how" an A/C system works ?

Just blow the humidity right out the garage door cracks ?!

Com-mon ..........lol .......... You can do better than that. Sounds like a bar story , and were not drunk yet.

Here's another bar story. I have an A/C duct to my garage and it works quite nicely, I have no return duct in the garage. The house was built like that so I assume it is to code and yes right now i'm sucken on a Brewski.


Willy Victor

 

[trovato]

If you get a fire in your home your insurance co will be laughing all the way to the bank when they see that in your garage and pull the plug on your insurance check .

.

I just had a chat with my State Farm Insurance agent and I asked him about this kind of thing. He says that basically your coverage is still in effect if you do something stupid. People who mess up their wiring are still covered. This should be in that same category. Think about it. Most fires are caused by people doing something wrong. Overloading the extension cord. Smoking in bed. The times he said that your coverage is in jeopardy is when you misrepresent the situation. Like saying you live in a house and really renting it out. Or saying it's strictly residential and running a business there. I'm not saying you should air condition your garage this way, just that your insurance should still be OK.

 

[thefairlaneman]

Others here know more about AC than me for sure, but having a way to vent the heat/fumes out the top is inportant. I have a power vent fan that pulls the hot air out making a very big differance in the comfort level of my garage.A window unit( 15/20 k BTU) using 220 if posible would be a good alternative to pulling off of your central air and safer.

 

[carguy123]

Not to be rude , but do you know "how" an A/C system works ?

Just blow the humidity right out the garage door cracks ?!

Com-mon ..........lol .......... You can do better than that. Sounds like a bar story , and were not drunk yet.

Yes, I DO know how an AC system works and it appears you are the one drinking the beer not me.

If you pressurize a box (garage) and there are leaks (the big garage door) then the overpressurized air inside the box will "leak" towards the lower pressure (outside). IIRC he or someone else was worried about humidity build up. The new air coming in will be the cooler, lower humidity air and the air leaking out will be the mix of "high humidity, hot air" and the cooler, low humidity air effectively controlling or reducing the humidity build up.

Now if he adds a return air duct, which would not be a good idea, then he runs the risk of bringing garage fumes back into the house - but it would control air temps and humidity better.

 

[DarrenD]

yes, but it isn't finished yet, new construction.
I am in Houston as well...
I am about a week or so from moving in.
4 car garage, with a seperate shop area @ 570 square feet, with a single roll up door and a 5 or so 3x3 windows.
Got a 2 ton unit going in this weekend for the shop area.
I need to pick up some insulation for the roll up door as you mentioned.

 

[all4sho]

yes, 4 ton heat pump unit for 2000 sq ft 12 ft ceiling

works very well

 

[edl]

also in houston - see post "use window unit inside"

 

[Aeroman]

Well, being an amature in this department, I enjoy reading all of your responses. I truly learn a lot. I just finished my 3-car garage (bought the house with a bare garage; no drywall, insulation, just 1 outlet and 1 light bulb) about 4 months ago. I insulated the ceiling, walls, and now have to add some of those Styrofoam panels from Lowe's on my garage doors. They are just the metal roll up kind, no insulation inside them. Before putting the drywall up in the ceiling, I installed a whole house fan between the joists to draw the hot air from my garage up and out to the attic. I had a roofer install two vents on the roof, including those rectangular soft vents on the side of the eaves. It works ok and it feels about 10º cooler in the garage but its still stuffy at around 80º to 85º or so. What I tried doing was running the A/C in the house, opening the door entry way to the house, and then putting a floor fan to blow the cool air into the garage, while running my whole house fan in the ceiling. All the garage doors were close. It kinda worked. I could feel the cooler air traveling more towards the floor into the garage. However, the hot, humid air would travel back into the house. So, it didnt really work. Thats why I have been lurking around in here for solutions to my garage heat issue - a wall mounted one may be the solution, and cost effective I think. Lowes sells this kind of AC unit for 100 bucks or so. Not sure on the BTU's. Just sharing my experience...