Is It Ok to Put a Furnace in the Attic?
Q: Is it alright to install a furnace in the attic? I have an about 800 sq. ft. house. I only have central air and wondered if a forced-air furnace in the attic would work better than a regular one in my basement?
A: This question is typically asked when there is not nearly enough space in the basement for a traditional forced-air furnace installation. In most cases, I recommend against this type of installation when you have space available in the basement area. You could probably do it in your case but with some significant caveats, which I will outline below…
First off, installing ANY equipment inside an unconditioned space can be hazardous due to the risk of carbon monoxide building up inside and harming you and your family. Think about it: your furnace is a combustion device that burns gas or oil, and this process creates CO (carbon monoxide) as a byproduct.
When you install a furnace in an unconditioned attic area, you typically need to add some exhaust system from the unit to outside air to dissipate the CO gasses created. In other words, when the furnace is running, all gases produced by the burning fuel have to be vented somewhere outside where they cannot harm anyone. If not appropriately vented, then you can create a hazardous situation that could lead to injury or death in severe cases.
I recommend against this installation, unless you have no other choice, because of the inherent problems with proper exhaust ventilation. You should also be aware that not all furnace manufacturers allow their equipment to be installed in unconditioned attic spaces, so be sure you check with your manufacturer before proceeding.
If, however, your house is less than about 900 square feet, then typically it would work OK but keep in mind that smaller homes are more prone to very extreme temperature swings, which can wreak havoc on a forced-air system trying to heat or cool the house. Also, realize that if you have an unconditioned space for your furnace, condensation will form inside the unit, which could cause cases…
One easy way to tell if you have an unconditioned space is to go up there and feel the temperature. If it’s significantly different than the rest of your basement (heating or cooling), then you probably need some insulation or weatherproofing treatment in that area.