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Question re fireproof insulation and leaks

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by Hitch, Mar 1, 2011.

  1. Hitch

    Hitch Member

    Joined:
    Mar 6, 2010
    Messages:
    105
    Loc:
    S.E. Pennsylvania
    I have a recently installed Harman pellet stove. When the stove was installed, the installers had to move over two outlet boxes to make room for the thimble. One is for power and the other is for a thermostat (for the future). After the stove was installed, the tile was installed. As a result of the way the tile was installed, I now have a gap between the thimble and one of the boxes. The opposite side of the thimble is the outside, so there is a fair amount of cold air blowing through the gap between the thimble and the junction box.

    Here are a couple pictures of the thimble and the junction boxes. Any suggestions on what I could use to plug up that air leak? I am concerned about adding something that is flammable. I really don't want you guys posting about me in that way......

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  2. Glosta

    Glosta Member

    Joined:
    Nov 1, 2009
    Messages:
    155
    Loc:
    North of Boston
    Great Stuff makes an expanding insulating fireblock foam.
  3. Don2222

    Don2222 Minister of Fire

    Joined:
    Feb 1, 2010
    Messages:
    6,987
    Loc:
    Salem NH
    Hello

    If the hole is larger than you could fill with a can of spray foam, then what I use is ROXUL comfort bat. You can cut it to any size and it is Fire Proof! >> http://www.roxul.com/residential/save energy with comfortbatt

    Below is a pic that may be similar to what you want to do.

    There was no insulation in the wall here. So after I installed a GFCI and Thermostat I added the Roxul behind the outlets and in between the outlets. What a difference. No cold air coming in anymore!! See Green Roxul below.

    PS. this is to keep a water pipe from freezing automatically!

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  4. Hitch

    Hitch Member

    Joined:
    Mar 6, 2010
    Messages:
    105
    Loc:
    S.E. Pennsylvania
    Thanks guys.

    I called the company that I bought the stove from. The guy said there is a sleave that goes around the actual exhaust where it goes through the wall. As a result, he said I can use any type of insulation for that crack/leak - or even in the space/void where the thimble is. He said that the sleave will prevent the insulation from touching the actual exhaust. He also said that I should make sure that there is no paper on the insulation, just to be extra careful.

    I would like to have some insulation in that void between the walls, just not sure how comfortable I feel about it.
  5. arnash

    arnash New Member

    Joined:
    Jan 24, 2011
    Messages:
    229
    Loc:
    land of giant redwoods, No.Calif
    Just shove some fiberglass insulation in that gap and you're done. I 'd remove the paper first. I've used fiberglass to fill in a gag between my old vermiculite "firebrick" insulation and the pellet chute. It's fireproof even at the highest flame level. It can't burn, only melt, but at a very high temp.

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