Where can a return air opening/register NOT be located by code?
Thursday, October 7, 2021
"Return air shall not be taken from a closet, bathroom, toilet room, kitchen, garage, mechanical room, boiler room, furnace room, or unconditioned attic,” according to the 2021 International Residential Code [M1602.2(4)] and the Residential Edition of the Florida Building Code.
But there are also six exceptions, and the basis of most of them is that a return air opening is allowed in some forbidden locations as long as the HVAC system only serves that area:
1) Return air opening in a kitchen is allowed as long as the system serves only the kitchen and is located not less than 10-feet away from cooking appliances.
2) Return air opening in a garage is allowed as long as the system serves only the garage. A return air opening in the garage for a system that also serves the living area of a home would be a fire hazard.
3) Dedicated independent dehumidification systems can take air from closets and bathrooms as long as the air is filtered and dehumidified before reintroduced into the spaces.
4) Taking return air from a closet is allowed as long as the return air serves only the closet, and it may be taken from closets that have no dedicated supply duct. There are also several further specs for closets less than 30 square feet.
5) Return air taken from an unconditioned crawl space cannot be done by a direct connection to a forced-air furnace, but a transfer opening in the crawl space enclosure is allowed.
6) Return air from one dwelling cannot be discharged into another dwelling.
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