Replacing Heat n Glo gas fireplace with Harmon Accentra Insert question about the flue

arpenn Posted By arpenn, May 16, 2008 at 7:47 PM

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  1. arpenn

    Member 2.

    May 16, 2008
    Southwest Missouri
    As the title indicates I am replacing a built in Zero Clearance Heat n Glo 6000XLT gas fireplace with a Harmon Accentra Insert with Zero Clearance Box. My question is in the flue. My gas fireplace has a direct vent flue that goes up through my roof. The direct vent flue has a inner liner that is 5" and an outer that is 8" (Double Wall) The inner vented the exhaust from the gas fireplace and the outer was the fresh air intake for the fireplace. My question is can I attach the flue from the Pellet stove to the inner 5" of my existing flue, or will I have to run a new 3" or 4" pipe up the existing flue? I am sure this is as clear as mud.

  2. webbie

    Seasoned Moderator 2.

    Nov 17, 2005
    Western Mass.
    Gas vent is not approved for Pellet exhaust. It is aluminum, whereas Class L (Pellet) is stainless steel.

    Furthermore, I'd have questions about even running a single wall pipe up through it unless that was an installation approved in the Harman manual or by the factory engineers (by fax). I have never heard of relining a gas vent for pellets.

    If you wanted to leave the old gas flue in place, you'd probably have to run a double wall pellet vent up the middle of it. Or, remove it and do the same......
  3. jtp10181

    Minister of Fire 2.

    Feb 26, 2007
    Madison, WI
    Yeah he is right, technically you can't run a single wall flex liner up through a gas vent. It would have clearances and I'm sure it would be fine but technically its not approved. If the run is straight up you could run the normal type L vent up through it.
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