In-WALL air return?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by tl2tl, Dec 9, 2008.

  1. tl2tl

    tl2tl New Member

    Messages:
    30
    I asked this elsewhere, no reply yet... What do you guys think?

    When our furnace was replaced, the installers put some new ducting in, including this 2nd floor air return duct. Each floor has separate ducting and it’s own furnace.

    Because this duct butts right against the door trim and goes almost all the way to the wall on the right, it’s hard to finish it with drywall.

    I am thinking of removing this return duct altogether, framing the area with 2x2’s and finishing with drywall. This way, the air return will be built inside a wall cavity and will actually have a slightly greater cross section area.

    Do you see any problem with doing it this way?

    Any suggestions on how to finish the inside walls of this new “duct� Should I paint it with glossy paint for smoother airflow or should I use any other special paint/finish?

    Thanks

    [​IMG]
  2. rmelo99

    rmelo99 Network Engineer

    Messages:
    349
    Location:
    Connecticut
    I've seen return trunks/runs created by panning sections of floor joists instead of using ducting, sort of what you are talking about doing.

    I think that isn't an approved way to do it everywhere or as wide spread as it used to be. In addition if you are going between floors, you have fire code concerns to deal with. Usually openings between floors must be sealed and/or blocked to prevent the speed of fire spreading. I would check with your building inspector before doing that.

    From a technical point of view, yes it should work because you are essentially creating a duct using a wall cavity.

    In my house we had a similar issue, with ducts and ceiling height.How bout just putting a 2x on the left to screw sheetrock into and glue the rest onto the duct. We're talking 1/2" here and u can do 3/8" if u needed to. Just my .02
  3. tl2tl

    tl2tl New Member

    Messages:
    30
    I never thought of a fire code affecting this, since the stairs to the upstairs don't require a door. But instinctively was thinking of using the concrete sheet rock to line the inside and the finishing wall of the new return. I think that would address the speed of fire spreading problem.

    The reason I can't just glue the drywall to the face of the duct is because it gives almost an inch when pressed, so the wall would not be stable.
  4. burleymike

    burleymike New Member

    Messages:
    118
    Location:
    Idaho
    They should have made the duct wider and less deep so you could frame up a wall. For fire proofing and air quality reasons I would not use the wall cavity as a duct, it used to be done like that though, talk to your inspector about it.

    The other problem with using the wall cavity is that if it is a 2x4 wall it will be much smaller than that duct reducing air flow. Assuming they calculated the duct size properly that will mess up your system. Especially if you have A/C you could end up with your evaporator icing.
  5. tl2tl

    tl2tl New Member

    Messages:
    30
    Yes, they should've done a better job installing that duct. Unfortunately, I have to deal with what it is.
    Part of the reason I was asking about the best paint/finish was the "air quality" consideration.

    As far as the size of the wall cavity, it actually will be bigger than the current duct, since all I'm doing is putting a wall between the 2 doorways that you see, after removing the duct.
  6. burleymike

    burleymike New Member

    Messages:
    118
    Location:
    Idaho
    What will work is to remove the existing duct and build a new wall like you want to do. Then line the new cavity with sheet metal and seal all the joints with mastic. You will save some money not having to have a shop make up a new duct.
  7. tl2tl

    tl2tl New Member

    Messages:
    30
    That's an interesting idea, but I'd rather not deal with sheet metal.

    What other material can I use?

    I am thinking of that foil lined insulation with an adhesive on one side. Would something like that be an acceptable alternative? What different types are there?
  8. gardner

    gardner DIY Senior Member

    Messages:
    224
    Location:
    Ontario
    It's a duct. Get some snips and gloves and learn to like it.

    If you will enclose the space, I would also look into opening up the wall behind the duct. If you can move the duct back into the space you can gain room on the front side. Even just removing a couple of inches of plaster and lathe will give you that much more space to work with.
  9. tl2tl

    tl2tl New Member

    Messages:
    30
    That's funny. :D

    Can't touch the wall behind the duct as it already houses a supply duct within it.

    I appreciate all the suggestions from everyone so far and I'm open to more ideas.
  10. rmelo99

    rmelo99 Network Engineer

    Messages:
    349
    Location:
    Connecticut
    If you dont want to deal with sheetmetal then you can use fiberboard duct material. One point to note is that because it is 1/2" or so thick, unlike metal ductwork that will cut into the inside dimensions of the duct run.
  11. tl2tl

    tl2tl New Member

    Messages:
    30
    Thanks, I was just reading about the duct board.
    That's one of the materials I am considering.
  12. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    You can use joist bays for cold air return provided no wiring or other mechanicals are in the same cavity.
Similar Threads: In-WALL return
Forum Title Date
Plumbing Forum, Professional & DIY Advice In-wall vent for waterfall drain?? Air Admittance Valve or cheater vent May 31, 2012
Plumbing Forum, Professional & DIY Advice Best sealant for connection to in-wall drop ear elbow - Teflon tape or thread sealant Feb 7, 2011
Plumbing Forum, Professional & DIY Advice Crane Walsan in-wall Toilet Questions Feb 28, 2010
Plumbing Forum, Professional & DIY Advice Leaking in-wall lav faucet valve Feb 22, 2010
Plumbing Forum, Professional & DIY Advice Powerful exhaust fan for in-wall use? Jun 3, 2009

Share This Page