Combustion test port in PVC class 4 vent?

Discussion in 'Water Heater Forum, Tanks' started by jtech1, Apr 14, 2019 at 9:17 AM.

  1. jtech1

    jtech1 Member

    Aug 31, 2013
    New Jersey
    Seems like there should be a better way to do this...

    For my Phoenix Light, most techs want to just drill a hole in my exhaust PVC at unit for combustion test port and plug it when done. Local inspector goes by manufacturer specs, which state NO unglued joints in PVC exhaust. Do I insist that the tech climb a ladder and do the test at the exhaust vent outside? Will the CO/CO2 values that need to be tweaked be as accurate at the exhaust vent? I realize that temperature reading will be different.

    Seems to me that someone should make a code approved PVC fitting for class 4 vents with test port in it. Looks like IPEX makes one but it is only certified when used with their 636 vent lines... marketing trick I am sure. I see others make their own with a PVC tee, threaded reducer and threaded plug... but, technically, that still violates the manufactures spec of no unglued joints, and local inspector will not approve it.

    How can manufacturer highly recommend this test to be done, but provide no approved way to do it? Running back and forth from outside vent, and tweaking adjustments that are easy to overshoot and have to back off, could be quite a workout... and is it as accurate?

    Feedback appreciated.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    The same way they can suggest using PVC pipe, but the pipe manufacturers do NOT approve doing so.
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  4. Sylvan

    Sylvan Still learning

    Sep 23, 2004
    plumbing- - fire suppression
    New York
    When I did asn efficiency test I would drill a 1/8 -1/4 opening in the flue pipe.

    Has anyone suggested drilling a 1/4" hole in the PVC and then tapping it (inside threads) and screwing a black or brass plug so it is still gas tight and allows for periodic inspections
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