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  1. #1
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,476

    Cold air returns through fire-rated walls.

    I'm wondering if an air return duct added to my HVAC system meets building codes, specifically for fire-rated walls.

    I have split system with upflow furnace and air handler in the garage. The furnace and air handler sit on a wooden platform which also serves as the air return plenum box. When I got my AC added, the single 10x20 air return duct was too small so they added a second 14x20 return. The original return inlet is in the front hallway, with the return duct going thought the garage wall. This return is high in the wall, and has about 8ft of duct to the return plenum box. The newly-added return is very short, going through the living room wall, with a very short duct to the plenum box.

    My question is regarding penetrations through fire-rated walls, which I assume is what separates my garage from the living room. Since the original return penetrates this wall, I would assume that fire-rated wall penetrations must be allowed for air return ducts, but I suspect there must be some constraints or requirements. So, I am wondering what the requirements are for these ducts when they penetrate a fire-rated wall. I am wondering if I should I have it looked at by a different contractor and redone correctly if it's not right.

  2. #2
    Join Date
    Jun 2006
    Location
    Richmond, VA
    Posts
    2,693
    Residential does not have very strict "fire rated walls" except for multi-family. Duct can be run thru fire rated walls with "fire dampers" to shut when the temp gets high. your original return runs thru the "fire rated wall" It's not required.
    It's not the Brand with the fewest repairs-It's all in the install!!! Attention to detail and using the best materials!

  3. #3
    Join Date
    Jun 2009
    Location
    Albuquerque NM
    Posts
    2,476
    Quote Originally Posted by beshvac View Post
    Residential does not have very strict "fire rated walls" except for multi-family. Duct can be run thru fire rated walls with "fire dampers" to shut when the temp gets high. your original return runs thru the "fire rated wall" It's not required.
    Ah thanks, that's what I was thinking but I wanted to ask to make sure. I don't think the original duct has a fire damper, but then again I didn't look.

    I'm also thinking of having the added duct changed due to noise from being so short, so that's part of why I'm asking.

  4. #4
    Join Date
    Dec 2000
    Location
    Auburn, New York
    Posts
    241
    I would check with you local code enforcement. If it is required and God forbid there is a fire, you may have a hard time with the insurance company.
    once you think you know everything, you'll never learn another thing!

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