Don’t you all wish you could add HVAC to a garage? I know I do. If you are like me you find yourself spending many hours every weekend doing various projects in your garage. The heat index here in Florida can get up to 110 degree’s so doing those projects and other “honey-doo’s” in the garage can be a bit exhausting. This article will help you in choosing the right way and wrong way to add HVAC to a garage.
The wrong way:
As a inspector we see plenty of handy man specials. Some are cosmetically not pleasing but are harmless while others are potentially life threatening mistakes. One of the biggest mistakes we often see is branching ducts off the main HVAC system to cool the garage since a home owner likes to work in their garage. First off this is a code violation. Some of you may be thinking “who cares, I have plenty of things that aren’t up to code in my home”. Fair enough, I do as well so let me give you a few reasons why its against code.
- Depressurizes the home
- Reduces indoor air quality
- Causes back drafting in gas appliances
Sounds bad doesn’t it? No, ok let me explain things a little further. When you branch off ducts off the main HVAC and have them discharge in the garage it will depressurize the home. A standard 2.5 ton unit will draw roughly 1000cfm. This means 1000cfm gets drawn in from inside the home and ideally 1000cfm gets put back in the home. This doesn’t happen 100% since there is a small amount that gets out by leaking ducts but its pretty close. Now if you add a vent or 2 you are putting about 200-300cfm into a unconditioned space that will never make it back to the return duct. This would be the equivalent of running 4 bathroom fans on all the time. This will cause the home to become depressurized and it will start to pull air from around recessed light fixtures, doors and windows that don’t seal well and the many various cracks inside your home.
Doing this will also cause exhaust gases that are supposed to go up through the exhaust flue on your water heater or furnace to be pulled back inside the home! And what gas is released up these pipes? That’s right, Carbon Monoxide. Now does this sound bad enough for you? So let me tell you the right way to add HVAC to a garage.
The right way:
The correct way to add HVAC to a garage is quite simple really. All you need to do is add a stand alone unit such as a mini-split system or a portable ac unit. This will separate the main HVAC system to just cool the inside and it will not disrupt the natural flow of the indoor air. Smaller stand alone systems can be had for $200 all the way to $2000.
You can find the code rules about HVAC here. If you wish for to have your home inspected to help you find any issues you may be overlooking you can reach us here.