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using b-vent for 2- 3" pvc pipes for condensing boiler

CPHNed
CPHNed Member Posts: 15
in THE MAIN WALL
Good afternoon all,
At a job i will be doing the only reasonable way to obtain exhaust/combustion air is to use the existing cast iron 10" b-vent as a chase. Any recommendations on sealing the b-vent when i remove the vent cap permanently? (or maybe i drill two 3 1/2" holes in vent cap)
I think it would look better to remove vent cap.
I was thinking of stuffing newspaper(to allow spray foam to set up) in the top of b-vent and spray foaming, and finishing it off with Gorilla waterproof patch/seal.
Thoughts?

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,495
    I would put a B vent cap on the top and hole saw a couple of holes in it. You can seal it with something. The other way would be to have a sheet metal shop make you some flashing you could solder on. A couple of sheet metal sleeves 3 3/4" diameter with 2 Ice cream cone flashings on it.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 9,401
    Is there such a thing as Cast Iron B-vent?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    SuperTechJUGHNEGGross
  • realliveplumber
    realliveplumber Member Posts: 354
    Do you know a roofer? They probably would have a few tricks up their sleeve.
  • CPHNed
    CPHNed Member Posts: 15
    Mistakenly omitted the word "boiler" Ed. I am sure you knew that...
    Thx all. I appreciate your time.
  • hot_rod
    hot_rod Member Posts: 23,405
    Venting a mod con? CentroTherm and others have kits for using an old B vent as the chase. I think they include the top flashing.

    https://www.centrotherm.us.com/products/innoflue-polypropylene-vent-systems/flex/b-vent-kits/
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • CPHNed
    CPHNed Member Posts: 15
    Here's what I'm gonna do. Most reasonably priced option.

    thx all.

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