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Stainless steel vent pipe

In February of this year we had a 2 year old SS vent system start to leak thru a finished ceiling in 6 different places.
We thought the new seals of these systems had taken care of the previous problems of disintegration of the SS pipe and of the RTV seal. Apparently we were wrong. The pipe manufacturer says the fault lies with the boiler manufacturer because their boiler produces acid with a low ph of 1, where other boilers produce a ph of 2. The boiler mfr says the problem lies with the pipe mfr.
Has anyone else had this problem, and if so, what did you do to correct it, if anything?
I can't believe we are the only ones experiencing this.


  • Nron_9
    Nron_9 Member Posts: 237

    check the grade on the pipeing system if you have low spots in the piping the water will pool and eat away the seals it should be graded at 1/4 " per foot back to the boiler ,this depends on the boiler though , check with manufactues rep
  • Ranger
    Ranger Member Posts: 210

    Is the vent run far or partially thru an unconditioned space?On the Crown product thay recommend pitching away from the appliance unless you use a horizontal drip tee &
    condinsate trap just before the drop into the inducer assembly.What type of vent termination is being used?Is the termination on the "windward"side of the structure?Is the termination obstructed in some way?
  • John MacGregor_3
    John MacGregor_3 Member Posts: 31
    SS leakage

    The vent is entirely inside the conditioned space.
    The pipe is pitched back (1/4" or more) to the drain tee at the boiler as specified in both the boiler and vent mfr's (Fas'N'Seal)instructions.
    It is in the middle of a windless woods.
    There is no obstruction.
    It has the mfrs (Weil-McLain) termination kit on it.
  • John MacGregor_3
    John MacGregor_3 Member Posts: 31
    SS vent pipe

    If power vent water heaters can be vented with PVC, why can't 80-90% boilers be vented with PVC or CPVC?
  • Jed_2
    Jed_2 Member Posts: 781
    Is this AL29-4C Gasketed pipe?

    Is the gasket end(or female) facing toward the termination hood? That way the condensate will drain over the gasket seal, and supposedly not deteriorate it. Or am I missing the point. You'e not sying the SS pipe itself is developing leaks, are you?

  • Matt Undy
    Matt Undy Member Posts: 256

    Power vent water heaters pull in extra room air through the draft hood to cool the flue gases. A boiler could do this i suppose but i can see where there might not be a sufficient market for it (wastes even more conditioned air up the flue, might as well go to a condensing unit, etc.)

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