Furnace exhaust pvc pipe leaking water at joint

Discussion in 'HVAC Heating & Cooling' started by eaglemtn, Apr 8, 2021.

  1. eaglemtn

    eaglemtn New Member

    Feb 4, 2021
    I had the furnace replaced three years ago. This winter I noticed water leaking from one of the pvc pipe joints in the exhaust pipe. I hung a bucket under the pipe to see how much water was leaking. I would guess that in a month's time in a MN winter, probably 2 quarts leaked.

    What would be the best way to seal this joint? The joint is part of several elbows - the pipe changes directions in this section. I would like to just seal up the joint instead of cutting this whole section out and redoing it.

    Would putting silicon caulk around the joint be sufficient? I was going to wait until summer when the furnace isn't working to make sure it's all dry in that joint.
  2. fitter30

    fitter30 Well-Known Member

    Feb 2, 2020
    Retired service tech
    Peace valley missouri
    Proper way is to cut a section out and use repair couplings and a short piece of pipe.
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  4. breplum

    breplum Member

    Oct 2, 2004
    Plumbing and heating contractor
    San Francisco Bay Area
    The original installers should be willing to fix for no charge since it was definitely poor assembly on their part.
    I don't recommend silicone, though that could work.
    Putty epoxy can work if esp. if you can rough up the area with sandpaper.
    The best product I can personally attest to is DuraCraft All Craft Epoxy. It cures hard, but it has held on some ABS 2" plumbing joints that I have been observing for years (as a working test).
    But you could try something cheaper as well.

    If you do have to cut out a section, we use 2" (or 3") no-hub couplings (the shielded, code approved type) all the time.
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