Posted on Aug 14 2013 by There are three air conditioning vents in this garage in Austin, Texas, and the ducts come from the from the main system in the house. Not only does this set-up violate the building code, but it can cause indoor air quality problems. Sometimes people do the craziest things. Take that photo at right, for example. That's a new home being built in Austin, Texas. The arrows point to three air conditioning ducts. Yes, they're air conditioning the garage. Mistake #1: Air conditioning the garage Now, the first mistake here was probably adding air conditioning to the garage in the first place. Most of the time, a garage is used simply as a garage. That is, the homeowners store cars, lawn mowers, high school yearbooks, a Smoking Donkey cigarette dispenser, a 'time capsule' in a shrimp factory box that you've had since your first job in high school, and that old Mr. Microphone. (Hey, Good Lookin', we'll be back to pick ya up later!) If it's just going to be used as a garage, there's no need to air condition it all.

It's a waste of energy that will provide the owners little if any benefit. If they've got some really valuable stuff that can't take the heat or humidity out there (like that Mr. Microphone), then bring it into the house.portable ac units for house How to Heat a Garagehvac unit 17 review questions Should I Insulate My Garage Door?how to determine the age of a carrier ac unit GBA Encyclopedia: Air Conditioning The Magic of Cold Window-Mounted Air Conditioners Save Energy Why is it a waste of energy? Because cars, lawn mowers, and junk don't need to be air conditioned. Also, standard roll-up garage doors aren't insulated or air-sealed, so you're paying to condition space that's constantly reheated by Mother Nature, especially if those doors get direct sun during the day.

Are there good reasons to air condition a garage? If I'm a woodworker and don't care if my cars sleep in the driveway, I'd air condition my garage in Austin. Or if I want to turn it into a mancave, momcave, or teen hangout, it's definitely gonna chill. Or maybe you can't build a house in a certain price range or Austin neighborhood without air conditioning the garage and have any hope of selling it. Mistake #2: Air conditioning the garage the wrong way OK, so let's say you've got a good reason to air condition the garage. That's fine, but you should absolutely never, ever do it the way they did here. Matt Risinger is an Austin home builder who owns Risinger Homes and does things the right way. The photo above is from a video he made to explain the problems with air conditioning a garage the way this builder did. The big potential problem here is bad indoor air quality. Let me show you why. An air conditioner is supposed to be balanced in its air flow. A 3 ton AC pulls 1200 cubic feet per minute (cfm) of air (nominal) from the conditioned spaceInsulated, air-sealed part of a building that is actively heated and/or cooled for occupant comfort.

and then puts 1200 cfm of air back into the conditioned space. What Matt showed above is a system that puts maybe 400 cfm of air into the garage. It's still pulling 1200 cfm from the house (assuming a 3 ton system) but only has 800 cfm left to put into the house. Hmmmm. 1200 out, 800 in. That’s like having a 400 cfm range hood running whenever the AC kicks on. That's gonna depressurize the house. One of the basic rules of air flow is that for every cfm in, you've got to have another cfm out, and vice versa. So if the AC is pulling 1200 cfm from the house and putting 800 back in, it's got to find another 400 cfm somewhere. It does that, as Matt said in the video, by pulling from the garage, under the walls, through the can lights, and also down a gas water heater flue if the house has one. That last one is potentially deadly. If the air conditioner pulls air down the flue while the water heater is firing, that means the exhaust gases aren't going up the flue. That's called backdraftingIndoor air quality problem in which potentially dangerous combustion gases escape into

the house instead of going up the chimney.. It can put carbon monoxide into the house and into your lungs while you're sleeping. Not such a good idea, eh? Even if you don't backdraft a gas water heater, you're pressurizing the garage and depressurizing the house. That means all the bad stuff in that garage air wants to find a way into the house. If that's not enough for you, how about the fact that the building code doesn't allow it? Just because it's not allowed, though, doesn't mean it doesn't happen, as the video shows. Building inspectors don't catch everything. The right way to air condition a garage If you really must air condition a garage, you need to install a separate system for the garage only. The best way to do this is with a minisplit heat pump or air conditioner. It's perfect for this application because it's small, doesn't require ducts, is very energy efficient, and can be turned off when you don't need to cool that space. Of course, another, less expensive, option would be to use window units.

They'll do the same thing for less cost. You'll get more noise and lower efficiency, but if it's not used much, that's probably acceptable. There you have it. As with most things, there's a right way and a wrong to air condition a garage. Then there's the question of whether you should be air conditioning it at all. Allison Bailes of Decatur, Georgia, is a speaker, writer, energy consultant, RESNET-certified trainer, and the author of the Energy Vanguard Blog. You can follow him on Twitter at @EnergyVanguard.If you start the installation in the morning, you’ll be enjoying cold air byA ceiling fan helps circulate the air and eliminate hot spots, but if the A/C unit keeps you cool enough, you can skip the fan. how to pick the right size unit for your garage and how to install it in the wall. In a hot garage, the heat and humidity slow you down, make you grumpy and increase your garage solves those problems and doesn’t cost a fortune.

You can buy a TTW (through-the-wall) unit for aboutWindow units cost a bit less, so consider going that route if you have a units are the same except for installation. A window unit comes with hardware and sealing gear for mounting it in a window, while a TTW unit requires a separate sleeve that fits into a wall opening that you frame into the wall. If you plan to use your garage A/C only occasionally, you don’t have to installIt’ll just take longer to lower the temperature to a comfortable level and the A/C compressor will run for longer periods, costing you more in electric bills. dramatically speed up the cool-down time and increase cooling effectiveness by hanging drywall on the ceiling. That reduces the size of the area to be cooled and helps the cool air circulate. Install a vapor barrier first, in case you decide to add attic insulation later on. But if you plan to frequently use the

garage A/C, it’s well worth insulating and finishing the entire space. Then size the A/C unit Measure the area of your garage (length times width) to determine the total square footage, then consult theApply the adjusting factors at the bottom of the chart. shop around for the best price on the A/C unit and a matching through-the- wall sleeve (an additional $100 to the cost of a window unit). Pick a location and cut the opening A/C units have weak circulating fans, so don’t locate one on the end wall of a locate it in the middle of the longest wall and aim the airflow toward theIf you’re installing a window unit and it’s located on the end wall of a rectangular garage, plan to install circulating fans to help move the cold air to the other end. Next, check the sleeve installation instructions for the rough openingSome manufacturers want a 1-in. clearance on the sides and top of the

Plus, the distance from the ceilingDon’t place the opening directly below the top wall plate.That’ll result in rapid compressor cycling and inefficient cooling. the top of the sleeve opening about 24 in. down from the ceiling (or as shown in the sleeve installation instructions). Then remove drywall (if any) in that location to expose the studs. center stud to allow for the thickness of the new top and sill plates. task is reworking the siding. most cases it’s best to remove as much siding as needed before cutting the opening in the sheathing and then to trim and re-side around the opening. Follow the manufacturer’s instructions to mount and secure the sleeve Run electrical cable to the location and install the receptacle. units require a dedicated receptacle on either a 15- or 20-amp circuit breaker (no extension cords allowed). sized from 9,000 to 12,000 Btu will typically

run on a 20-amp, 120-volt circuit. But you’ll have to install a 220-volt circuit Other A/C options for your garage We didn’t cover portable A/C units in thisThey’re an option but not a veryPortable units use cold air from the room to cool the condensing coil and then exhaust that air to the outdoors. negative pressure this creates inside the garage draws in an equal amount of hot humid “make-up” air from outside. portable unit then has to cool that makeup air and the cycle repeats over and over, wasting 30 to 50 percent of the rated capacity of the unit. units don’t come close to the efficiency of a window unit or a TTW unit. If you want the very best cooling option and are willing to dig deep (expect to pay about $4,000), contact an HVAC company and get quotes on a split system. Those are heavy-duty units that can quickly cool your garage and maintain the temperature even under the hottest