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What is the right way to seal a wood fireplace when installing a gas insert?

Post in 'It's a Gas!' started by SolarAndWood, Nov 27, 2009.

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  1. SolarAndWood

    SolarAndWood Minister of Fire

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    My sister just moved into a house that the previous owners had installed a VC gas insert into an existing wood fireplace. While, I was relighting the pilot for her, I noticed a 10-20 mile an hour breeze going up the chimney. What is the best way to seal it? Also, is there anything that should be done to insulate the firebox of the old fireplace to keep it from sucking the heat out of the insert? Thanks much for the feedback.

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  2. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    Others here may disagree with me, but I would use unfaced fiberglass insulation.
    I have installed maybe 100 or so of them this way & that includes my OWN home.
    Jam as much insulation into the damper area on all sides & between the liners...
    Also, I'd pull the chimney cap & insulate that area as well...
    Then re-silicone the cap to the flue tile...
    This method will essentially give you a standing column of "dead" air
    between the insulated areas...
    This "air column" will also act as insulation.
  3. jtp10181

    jtp10181 Minister of Fire

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    I don't disagree with you about the fiberglass insulation on GAS inserts. The manuals for the inserts we sell specifically state to seal the damper area with fiberglass insulation. Works well for us also.

    Not something I would recommend doing for a wood insert though.
  4. SolarAndWood

    SolarAndWood Minister of Fire

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    Thanks...do I need to do anything with the firebox itself or do the gas inserts do a good job of sending the heat out the front anyway?
  5. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    Once you've insulated the damper area, the heat has NOWHERE
    to go but out into the room, whether it's forced by the blower or not...
  6. SolarAndWood

    SolarAndWood Minister of Fire

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    I thought an external masonry chimney would suck the heat out of the firebox?
  7. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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    There may be some semblance of heat loss, until the masonry around
    the insert actually heats up, but it shouldn't be that bad.
    My gas insert is in a masonry structure that is in the DIRECT north wind
    AFTER that wind passes across a lake. In the middle of the winter,
    when the lake is a 73-acre ice cube, my insert will still start to throw
    heat into the room after about 10 minutes of burn time...
  8. SolarAndWood

    SolarAndWood Minister of Fire

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    Cool...thanks.
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