LP Gas Direct Vent Insulation Discussion
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  1. #1

    LP Gas Direct Vent Insulation Discussion

    I have an LP gas fireplace that I believe is direct vent that I'd like to "seal in". It is an insert that is living in my old fireplace spot in the chimney. I want to prevent all outside air coming in from coming down the chimney. The company that installed it just stuffed a bunch of un-faced pink insulation up there around the vent pipes. That looks like a bad idea to me and isn't air tight. I'd like to use rigid foam and fire-blocking spray foam if possible. What's the best way to do this?

  2. #2
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    The manuals for the inserts we install specify to use fiberglass batting to seal the damper area. The only other thing I would ever use is a metal block off plate. I would not put rigid foam in there or spray foam as it may start to melt and create an odor.

  3. #3

    Air Tight

    Thanks for the idea. I didn't think about the foam melting and I really don't want that. What I do want though is an air tight seal.

    I don't have any issues with the pink bats other then them not being air tight and I'm worried they are to close to the vent pipes.

    Should there be a 2 inch gap between the bats and the vents?

    Any ideas on how to use the bats and metal to make an air tight seal around the vents?

  4. #4
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    Check the install manual for your insert, it probably says to pack fiberglass insulation around the vent at the damper area, in which case it is OK to have it there.

    Here is some info about making a metal block off plate for wood inserts which should help you get an idea.

    http://www.hearth.com/econtent/index...eal_is_needed/
    http://www.hearth.com/econtent/index...ock_off_plate/

  5. #5
    Join Date
    Nov 2009
    Posts
    9
    Just seal the termination plate at the top with hi-temp silicone and shove insulation around the pipe up top. Then layer insulation around the damper and pipes. You should have no cold air transfer. If you are worried about heat melting the insulation, use hi-temp ceramic fiber insulation. Otherwise fiberglass insulation is approved by most insert manufacturers.

  6. #6

    Help

    Started the project and ran into some issues. I used pink bats and stuffed them up in there and then formed a 26 gauge piece of galvanized steel and pushed it up in there with two circle cut outs for the vents. Two questions:

    Should the vents be attached to the fireplace with with anything other the screws? The manual suggests this but it wasn't done in the first place. I have the Valore Legend G3.

    I can't attached the plate because the area all around the fireplace is solid iron or steal. Nails and screws are cutting it. I tried a hammer drill and tapcons and no go. Can I use a hi-temp or regular temp cold weld product to attach it? Like Thermo Steel or JB Weld?

    I want this to be air tight and have the furnace cement and silicon but need a way to attach the plate in. I'll post pics if requested.

  7. #7
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    Anywhere right up against the exhaust vent silicone will not hold out very long, so you would have to use furnace cement, which BTW gets brittle and falls apart anyway, nearly useless. Everywhere else you will be fine a high temp silicone.

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