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steam boiler fills when fails

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albcorb
albcorb Member Posts: 4
in THE MAIN WALL
I have 2 steam boilers feeding the same main for a building in Boston. The system supplies a heat exchanger for domestic tank(500 gallons+/-)and common area heaters
#1 is a weil mclain with a powerflame gas burner and #2 is a HB Smith with same burner. When #1 boiler fails for any reason it will eventually flood. I have gone through the feed floats and makeup. A few things faulty but replaced. Worked well for weeks than failed on gas press. and filled again. Both boilers are fed by condensate pump, piping has check valves and it feeds into the return and has siphon trap. Both boiler lines drop into the main feed lineat approxomately the same height. Both boilers about the same size(btu's). I see a few pipe design issues but none that would cause this problem. There are no hartford loops on either boiler, no common returns, supplies off each same size and drop into header about 2-3' apart.#2 boiler will not flood if left off. #2 is about 2' lower at the base but steam lines rise to same height. #1 boiler is 1/2 the distance to the main than #2. Everything works as it should until #1 fails. Then it floods. Any ideas???

Comments

  • ttekushan_3
    ttekushan_3 Member Posts: 964
    insomniac wonders

    if boiler one is half the distance to the main, is boiler two's steam traveling past boiler one's outlet and filling it from the top through steam condensation?

    I'm not sure I'm visualizing it properly tho' so a photo or several would be helpful, yo.

    -Terry

    Terry T

    steam; proportioned minitube; trapless; jet pump return; vac vent. New Yorker CGS30C

  • Patrick Linhardt, \"Linhardt's Field Guide to Ste
    Patrick Linhardt, \"Linhardt's Field Guide to Ste Member Posts: 152
    on the right track, but get some sleep

    Hi Terry,

    The steam from an "on" boiler will travel to and condense in the "off" boiler if the supply of the off boiler is not valved off. This will then cause the "off" boiler to flood.

    Why it only happens to one of two boilers on this job I can't explain at this point.

    The solution is a waterline trap. An F&T trap located just above the normal waterline, piped off the equalizer portion of the Hartford loop above the tee in the vertical piping. Weil-Mclain shows it in their LGB install manual on page 20.

    Best regards, Pat
  • albcorb
    albcorb Member Posts: 4


    Hey Pat,
    Yep you are correct. I was back out there today.It happened to the #2 boiler. It takes about a week but it filled also.
    What troubled me was there is a trapon the boiler. After a revisit I realized it was ABOVE the sight glass level not the average waterline. The #2 boiler doesn't have one at all. I recommended lowering the one existing trap and adding one to the other. Thanks for your input guys.
  • Patrick Linhardt, \"Linhardt's Field Guide to Ste
    Patrick Linhardt, \"Linhardt's Field Guide to Ste Member Posts: 152
    glad to help

    Glad to help and that it makes sense now.

    Best regards, Pat
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