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Flue Pipe

Bob Harper_2
Bob Harper_2 Member Posts: 54
ditto Brad. While not a code issue, seams tend to hold condensate, where it rots the pipe faster. I always place them deliberately up and, of course, staggered. 3 screws per joint, braced with drives, meets clearance (18" unless mfr. states 9"). Try to get as much vent rise as possible before any offsets. The test hole for the combustion analyzer should be 1.5 duct diameters from any collar, ell or tee so plan ahead.

For full details, see NFPA 211 and 31



  • Darren_12
    Darren_12 Member Posts: 1
    Flue Pipe

    On flue pipe in general, does it matter where the seam is on a boiler or water heater? How far into the chimney should the flue pipe extend?

    Thanks for your reply.
  • Brad White
    Brad White Member Posts: 2,398
    Flue Pipe

    Interesting on the seam- I have seen it on the bottom probably for looks as well as on the sides but never thought about it, frankly. (Bottom seam is what I have on my 1986 Burnham 204 but it is no longer active.) No leaks that I can see but I will wait to hear what others say.

    As for depth into the chimney, no further than flush with the inside of the liner tile. I have seen them thrust to the opposite wall with near disastrous results. No reason to go further in. Any debris that may fall will catch and block the flue and any protrusion may impinge flow from a lower appliance is how I see it.
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Bruce Stevens
    Bruce Stevens Member Posts: 133
    When I went to school for oil burners

    I was taught that the seam belongs on bottom as the seam acts as a spine and if the pipe rusts the seam acting as the backbone will help hold things together longer to give more time to be found and repaired. Otherwise it could just drop out with collecting debris and condensation which as we all know eats away at the old smoke pipe. So I always put on bottom and behind for looks.

    I have been around Brad, but wife has been on a decline health wise again so I have been putting more time in at the house. The daughter moved back from Baltimore this week so that should take some the house chores away from me again.
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