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Steam returning to condensate pump, coming out of vent pipe.

AeroChad Member Posts: 1
I have two pipe steam system with two zone valves, a condensate pump, I am having a problem of steam returning to the pump when both zones are calling.  I shut off one zone and  the stops steam stops.  When main is calling by itself, does not steam and reg. pressure fine.  pressuretrols set at 1.5lbs, also adjusted water level in boiler.  can provided additonal info if needed.


  • sreja
    sreja Member Posts: 175
    re: Steam returning to condensate pump, coming out of vent pipe

    I'm just a home owner who went through a process of getting self-educated about steam myself a couple of years ago, so take my thoughts with a giant dose of skepticism and wait for the pros to reply.

    BUT.. It sounds to me like what you have is some failed traps that is letting steam into the return line.  We had this too in our system, and it filled the boiler room with steam coming back in from the return lines.  Solution: Replace the broken (or all) traps.  These are traps at output side of radiators and/or any main line traps.  It's not infrequent that traps fail in the "open" state and will let steam pass.

    Second piece of advice is to go buy one or more of Dan Holohan's books from this site -- they are invaluable for learning stuff like this.
  • Jamie Hall
    Jamie Hall Member Posts: 21,568
    Going to need...

    a good diagram of the system for this one -- showing what you have in the way of steam mains, dry returns, drips, and wet returns -- and any traps particularly on the mains.

    Also, just where the zone valves are, and how condensate in the mains returns when the zone valves are closed.

    As sreja notes, the problem may well be a failed trap or traps -- not at all uncommon.  But there are other sneaky ways for steam to get into a condensate return tank (disclaimer here: I, at least, don't like them -- at least on residential low pressure systems.  Gravity is so much simpler...).
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Brad White
    Brad White Member Posts: 2,393
    I agree, start with traps

    When you shut off "a zone" and the steaming stops, is it a particular zone? Narrow it down a bit?
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
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