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Flues Too Close?

Post in 'It's a Gas!' started by Ratmandu, Feb 11, 2009.

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  1. Ratmandu

    Ratmandu New Member

    Joined:
    Feb 6, 2009
    Messages:
    11
    Loc:
    Norcal
    HI

    I am buying a house with two fireplaces, I would like to put a gas insert on one side, and a wood insert in the other. The flues terminate at relatively the same height, with their centeres about 1.5' apart. I will probably be running both at the same time very seldomly, but will this cause a problem for the gas stove if the woodstove's exhaust gets into the intake of the DV furnace? IF so, what can I do to alleviate that situation?

    Thanks in advance,

    Scott

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  2. DAKSY

    DAKSY Patriot Guard Rider Staff Member

    Joined:
    Dec 2, 2008
    Messages:
    4,994
    Loc:
    Averill Park, NY, on Burden Lake II...
    You're gonna hafta extend the wood burning side higher than the gas burning side.
    This will probably mean a liner on the wood burner, then a Class A adapter plate,
    then a length of Class A & then your cap.
    Probably gonna need a roof brace kit, as well, with this set up.
    You want to make sure that the exhaust from the wood burner won't be sucked back into the
    intake of the DV unit, or the DV unit will soot up as it tries to burn O2 deprived air.
    This is why the DV intakes are lower than the exhaust side.
    The problem that MAY happen with this set-up, is that you MAY get CO from the gas unit drawn
    back into the woodburning system when it's not in use.
    It seems that this condition can occur if you have a BIG negative pressure situation at
    the wood burning unit location...
    I think I'd have my house pressure checked to see if this is a possibility...
    HTH
  3. Ratmandu

    Ratmandu New Member

    Joined:
    Feb 6, 2009
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    11
    Loc:
    Norcal
    Thanks-that all makes sense. Any idea about how much farther above with the woodburning side? I understand that a few other factors might come into play-such as prevailing winds, etc.
    Scott
  4. DAKSY

    DAKSY Patriot Guard Rider Staff Member

    Joined:
    Dec 2, 2008
    Messages:
    4,994
    Loc:
    Averill Park, NY, on Burden Lake II...
    Per NFPA 211 there is NO specified height, but I'd wanna get it at LEAST a foot above the DV cap.
    I suppose you could find the install manual for the insert you have in mind & THAT may give you
    the actuals...
  5. Inside Guy

    Inside Guy New Member

    Joined:
    Nov 14, 2008
    Messages:
    37
    You shouldn't have any problems;
    I imagine you only burn wood once in a while.
    It take some unique circumstance for the wood exhaust to cause a performance issue with a dv insert.
    Ideally, you'd want the wood exhaust higher, but in your case its not worth the expense. Just avoid burning
    Both at the same time and you won't have any concerns!
  6. jtp10181

    jtp10181 Minister of Fire

    Joined:
    Feb 26, 2007
    Messages:
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    Loc:
    Madison, WI
    Make sure they install two FULL liners for the DV insert, one exhaust and one fresh air. If this is done it will prevent wood smoke from coming down the flue when the gas unit is not in use. You MAY get smoke coming down while its in use but it would not get into the house. I would say leave it be and then if the smoke causes problems with the gas units operation, then consider extending it higher.
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