GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Where to terminate an abandoned vent pipe for old power-vented hot water heater?

Andrew_C | Posted in General Questions on

Michigan, Zone 5.  I am replacing an old power-vented hot water heater with an electric water heater.

 

Question: where, and how, should the abandoned vent pipe be terminated?

 

The water heater is in the basement.  The power-vent goes straight up through the first floor (behind walls), thru the attic, and out the roof, terminating in a downward hook.

Should I cut it off in the attic somewhere above the insulation level and just cap both ends of the tube?  Cut it off in the basement near the ceiling and cap it there?

Should I leave the roof termination as is?  [That’d be preferable, because it’s a really steep roof, and technically it’s outside of my control as it’s a condo.]

Thanks,

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. Expert Member
    MALCOLM TAYLOR | | #1

    Andrew,

    I'd leave the roof cap termination alone. They can remove it when the roof is redone - hopeful some years from now. If it's easy, cut the duct close to the underside of the roof and seal the end. Otherwise cap it at the ceiling of the room it comes from.

  2. Expert Member
    Dana Dorsett | | #2

    Cutting it in the middle is potentially risky, lest somebody think it's still complete and hook up another burner to use it at some future point. If you're going to do that it's better to pull it all out and just cap the it a few feet below the roof terminator kit.

    Otherwise, capping it at the bottom-only is fine. There will be a tiny heat leak due to convection in the pipe, as well as a bit of conducted heat loss, but the total energy cost is miniscule as long as it's capped.

    1. Expert Member
      MALCOLM TAYLOR | | #3

      "Cutting it in the middle is potentially risky, lest somebody think it's still complete and hook up another burner to use it at some future point."

      I really good point I didn't think of.

  3. Andrew_C | | #4

    Thanks Malcolm and Dana,
    Capping it at the bottom only in the basement/mechanical room sounds like an easy option; I'll do that.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |