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  1. #1

    External Air Intake SNAFU

    I'm trying to figure out how to install my Quadrafire 7100 and when I was looking closer as to where I would making the hole for the external combustion air intake, I discovered that the hole would be right at the intersection between the brick chase exterior side and the wall (for some reason, in my mind, I thought I could go straight out -not true). Take a look at the photo, it seems the centerline of the hole would be right at the intersection.


    It's a tight fit and I really don't have room for flex tubing and relocate the intake.

    I was wondering it would be possible to simply frame in a channel that will connect the inlet on the fireplace and the external air intake. I know return air on central air is done similar to this when they route the return air between two 2x4s 16" apart.

    Thanks!!

  2. #2
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    We have done similar to this but we have a metal offset boot made that goes in there.

    You should check with the AHJ (inspector) to see if they would allow that. I do not see where this would cause any problems as long as its sealed up good, but there could be a fire spread concern by the inspector.

    BTW, very nice work on the pictures.

  3. #3
    Join Date
    Aug 2004
    Location
    S.E. Pa
    Posts
    6,277

    Cool go to mfr.

    The AHJ would most lifely need a signed drawing from the mfr. approving a modification. The danger with offsets is reduction in airflow, which affects not only combustion but the heat signature of the entire fireplace/ stove. I would be nervous about not hard ducting this intake because if that inlet is located in a negative pressure zone, such as due to wind, it can suck fire out the vent, which I've seen.

    No, HHT needs to correct this engineering snafu. Classic case of R&D not listening to or asking field ops what is needed and what works. They used to be very responsive on such matters but like everyone else is cutting back on staff, R&D budget, etc.

    Love the illustrations--Google Sketchup or another CAD?

  4. #4
    I'll definitely make a sheetmetal box to put in there. This is when I wish I had a small sheetmetal brake to fab up a box real quick. Do you make your own sheetmetal offsets or hire that out? I guess could cut up 6 sides, tack weld them together and then use foil tape to seal up all the corners.

    I had some concern about an offset being too restrictive, but it's pretty short offset and has plenty of flow area. It probably not be nearly as restrictive as a long run of flexible duct work.

    Hearthman, thanks, I made the illustrations in PowerPoint.

  5. #5
    Join Date
    Sep 2010
    Location
    LA
    Posts
    198
    I would think with the manufacturers Ok and the Inspecting Authority approval the metal offset box would be a perfect solution to your problem.

    I thought Fresh Air intakes on all fireplaces were behind refractory panels or internally ducted to front of unit, so not sure how it could suck flames from the firebox in a given negative pressure. Thats probably why the allow ducting with that foil flex down here.

    Good Luck with the solution, Oh, your art work leaves me wishing I could that!

    Mike...

  6. #6
    Posted by intakefan - Cold Air Intake

    I had a cold air intake and went into a deep Puddle and the engine sucked up some air but it was not that big a deal.
    anyone know about k and n, they seem to be priced about the same?

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