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flue pipe mystery

zepfan Member Posts: 315
looked at a job today were we would be installing a new 80% furnace.the existing flue riser while it is of ample size (6") it does not appear to be standard double wall b vent.this is a pipe that is metal on the inside an outside has a thick almost plaster material.does anyone know if there is a way to connect b vent to this? or is the only alternative to install a liner,because i will also need to connect the water heater,were someone has just stubbed single wall pipe into it,and sealed it with tape any suggestions would be much appreciated.i have attached a picture thank you


  • furnacefigher15
    furnacefigher15 Member Posts: 514
    I think

    That is all fuel pipe, or other low clearance rated vent material.

    The inside diameter of that pipe may only be 4 or 5 inch.

    If you can get the correct size liner through the existing flue, do that.

    If not it might be easier to start over, the low clearance / all fuel vent materials are very expensive, and must be matched to the original in order to maintain the listings, and approvals of the various agencies.
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    Old 'A' vent

    It is an older style of A vent, originally designed for venting oil appliances, the uppert tee looks like an old Selkirk Metalbestos style and the lower tee is a subsequent replacment, much newer, different brand.  Certification was toasted when the tee was changed.

    A lot of these old vents had corrosion issues due to the stainless inner liner and galv coupler and outer jacket.  It should be viewed as suspect due to it's age.
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  • zepfan
    zepfan Member Posts: 315

    the i.d. of this vent is right at 6",and the size liner we would need for 106,000 btu's is five inch, so we should be able to install a new liner if we do the anyone know if this existing flue contained asbestos? thank you so much for your help with this matter.
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