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Wood Stove Pipe Question

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by DatPhat, May 3, 2013.

  1. DatPhat

    DatPhat New Member

    Joined:
    May 3, 2013
    Messages:
    3
    Loc:
    Seattle, WA
    Hello, I'm a newb in this forum, go ahead and scold me all you want, but I heard that this is the best place to go for wood stove questions. I've tried searching around but couldn't find any info in the forum.

    After replacing my gas furnace with a hydronic furnace connected to a tankless water heater, I'm left with double-walled direct vent pipe going through two floors to the roof. I have been throwing around the idea of re-purposing this to an extra air intake source for the furnace OR using the pipe for a standing wood stove in a 500 sqft room.

    I didn't include the wet (mechanical) room to be supplied by the furnace so it can get cold in the night. In addition, I love natural fires, and thinking about making the space into an office.

    QUESTION:
    Can I use the double-wall gas exhaust pipe as my chimney pipe? I assume no, as I have read elsewhere because of temperature ratings.
    In which case, can replace the pipe and run stove pipe through floors? I assume no, since I read an article on Hearth.com here.

    Basically, Can I do what I want and re-use the existing holes in my house to allow heat and smoke to go through them with using a free-standing wood stove? Even a possibility? I'm sure this has been done before.

    Thanks a bunch, I think the answer is just NO.
    But I figured I'd ask some experts. I'm sure I'm not the first to ask nor the last so maybe this will help someone else too.

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  2. DatPhat

    DatPhat New Member

    Joined:
    May 3, 2013
    Messages:
    3
    Loc:
    Seattle, WA
  3. begreen

    begreen Mooderator Staff Member

    Joined:
    Nov 18, 2005
    Messages:
    46,954
    Loc:
    South Puget Sound, WA
    Welcome. Good thing you asked. Gas vent pipe can not be used for a wood stove. It's temp rating is much lower. You can replace the pipe, but it must be class A high temp at the stove room ceiling on up through the roof. You'll have to install a ceiling support box and will need to enlarge the holes through the floor to accommodate the class A pipe clearance requirements.
  4. DatPhat

    DatPhat New Member

    Joined:
    May 3, 2013
    Messages:
    3
    Loc:
    Seattle, WA
    Thank you for your quick reply.
    I've found that I need an attic radiation shield around the opening to the attic but does that allow draft from the attic and the room? Can I use a similar support box instead of the radiation shield?
    What kind of shield do I use on the actual roof opening?
    Also, does the Class A pipe need to be enclosed in the open space? Does it got hot to touch when used although it's triple insulated??
  5. webby3650

    webby3650 Master of Fire

    Joined:
    Sep 2, 2008
    Messages:
    4,316
    Loc:
    southern Indiana
    You will likely need an attic insulation shield as well as the ceiling support box. The box holds the chimney up and the shield prevents insulation from touching the pipe. On the roof you will have a metal flashing, it will be made so that the proper clearances are maintained through the roof penetration. (When installed properly) ;)
    The pipe will only need to be enclosed if it's exposed in the living space.
    It will be warm, but it rarely get too hot leave your hand on it.

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