Expert: Fred Weldin - 11/16/2011

Question
Fred
You had answered a question some time ago about a gas furnace in a garage. To expand on that question there was a closet mentioned. My garage is not attached to the house. Is the furnace required to be in a closet or can the furnace be freestanding?? What are the clearance requirements around the furnace? It will be LP and have the fire source over 18" above the floor.
Thanks

Wayne

Answer
Wayne:

A closet is not required, but protection from the vehicle(s) is. If there's no protection (parking bumper or pipe bollard), the furnace must be at least six feet above the floor. If the furnace is in a closet, and the closet door opens to the outdoors, the 18" is not required provided combustion air is not taken from the garage.

Clearances are found in the manufacturer's Installation Instructions. "Combustibles" include drywall here, and even fire-rated drywall is "combustible".

If there's ductwork, the supply plenum and the first three feet of supply duct must be metal, and you'll probably see all that requires one inch clearance.

If the furnace is in a closet, a return duct is required, and it must be sealed airtight within the closet.

Equipment access: 30x30 working space in front of the furnace, door 36x80 (if there's a closet), a light and a receptacle must be near.

A gas-fired unit heater sounds like your best bet cost-wise.

Fred