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Vent pipe on Steam condensate tank

beanbean Posts: 34Member
edited October 2018 in Strictly Steam
Can anyone explain to me the WHY & WHERE when it comes to the termination of the vent pipe off the top of the Steam condensate tank? Your help is greatly appreciated!!Also , what I mean to say is that I have seen these lines taken up to a certain height & goosenecked! Why?


  • Mike_SheppardMike_Sheppard Posts: 439Member
    All of that information should be in the manual. A condensate tank/feedwater unit is not designed to be pressurized. The vent ensures that the tank does not see pressure. The vent is also where the air in the steam system leaves.

    B&G says pipe vent to atmosphere. Do not restrict size of vent. And no more than 20 feet vertical unless an overflow is provided.
    Never stop learning.
  • Jamie HallJamie Hall Posts: 10,404Member
    To which I might add -- if you ever have the misfortune to have a failed trap elsewhere on the system, you are going to have steam coming out of that vent. So it should terminate somewhere where that isn't going to be a hazard.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Mike_SheppardMike_Sheppard Posts: 439Member
    Jamie is absolutely correct.

    We had an apartment building that had A LOT of bad traps. Their solution, instead of fixing the traps, was to just run the vent line outside so it would stop steaming up the boiler room. Well, they had a large 3-phase disconnect for the boilers outside as well. And they terminated the vent line directly underneath it. Ended up shooting steam into it and judging by what it looked like afterwards, it was quite the arc.
    Never stop learning.
  • delta Tdelta T Posts: 746Member
    @Mike_Sheppard saw one like that about 6 months ago, less the 3 phase disconnect, but it did cause a huge ice patch on the north side of the building that purportedly did not melt until sometime in May.

    I might add, that I always will terminate the vent with a bare pipe (no threads) so that future knucklheads cannot easily put a cap or a valve on to 'fix' the leak. Pressurized condensate receivers can be scary things....
  • JUGHNEJUGHNE Posts: 5,652Member

    Could this one have been passing steam??
  • JUGHNEJUGHNE Posts: 5,652Member

    But wait! there is more!!
  • PumpguyPumpguy Posts: 355Member
    I was told the reason for the elevation of the pressure vent pipe was that in the event of power failure, the system would gravity flood to the level of the boiler line, and then recirculate.

    I assume this concept originated in the days of coal fired boilers.
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