Have you ever wished you could add HVAC to your garage? I know I have. If you’re like me, you probably spend a lot of weekends working on different projects out there. Here in Florida, the heat index can reach 110 degrees, so tackling those projects and other chores in the garage can get pretty exhausting. In this article, I’ll walk you through the best and worst ways to add HVAC to your 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 ducts off the main HVAC and discharge them into the garage, it will depressurize the home. A standard 2.5-ton unit will draw roughly 1000cfm. This means 1000 cfm is drawn in from inside the home, and ideally, 1000 cfm is put back into the home. This doesn’t happen 100% of the time, since a small amount escapes through leaking ducts, but it’s pretty close. Now, if you add a vent or 2 you are putting about 200-300cfm into an unconditioned space that will never make it back to the return duct. This would be equivalent to running 4 bathroom fans continuously. This will cause the home to become depressurized, and it will start to pull air from around recessed light fixtures, poorly sealed doors and windows, and 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 simple. Add a standalone unit, such as a mini-split system or a portable ac unit. This separates the main HVAC system from cooling only the inside and does not disrupt the natural flow of indoor air. Smaller standalone systems cost $200 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.