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Where to install trap on drip?

Looking for advice as I continue to work through some steam hammering issues. I have a two pipe steam system on 17 unit 2 story apartment building. The once wet returns along the perimeter of the basement has a condensate pump now at the boiler making it a dry return from what I understand. Main ends have drip legs that drop directly into the dry return. I want to add thermostatic vertical traps in the drips to stop steam from entering the condensate line where the hammer is occurring. This was recommended a less expensive alternative to f&t traps...How far down should it be installed to provide adequate drainage while not backing water up into the main? Picture of drip in question is below.. thoughts?


  • Jamie Hall
    Jamie Hall Member Posts: 21,553
    A foot or two is ample height above the standard thermostatic trap.

    I have to admit that I'm sitting here wondering if in some ways it would be simpler to ditch the condensate tank and pump and controls and aspirin and go back to how it was originally done -- and meant to be done...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 13,834
    Agree wit @Jamie Hall
  • Mrmarky
    Mrmarky Member Posts: 10
    @Jamie Hall thanks for the response... I considered that as well but it seems I may have some
    Boiler water line issues if I do that and may be why the pump was added when the newer boiler was installed some
    Years ago. So If I go the trap route and leave About 2 feet height above the trap I should get the same result?
    JUGHNE Member Posts: 10,801
    Did you see any evidence of main air vent locations on old piping?
    If you use rad traps for the returns/main drip should you then have a cooling leg on each in order to allow the element to open for condensate return?