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Steam Trap?

What is this items function, and what should it be used to be replaced with? Im assuming some type of steam trap, with a vent attached? .


  • Gordo
    Gordo Member Posts: 857
    edited December 2021
    That looks like an old Dunham Vapor System "vent trap", which is confusingly not a real "trap" in the thermostatic sense.

    It has a float in it which was there to keep water from squirting out of the system if the coal fire back in the day got too much and caused the pressure to get too high (high pressure in your case is greater than 16oz/in2 or less).

    The "trap's" main function was to let the air out of the system, and thus to allow steam, or "vapor" as low pressure steam is called, to flow into your radiators.

    Best to up-grade the vent (that's the silver bullet-like thing poking up thru the hole in the ceiling) by making that hole bigger and putting on a bigger, better vent such as a Gorton #2.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • Wahlheating
    Wahlheating Member Posts: 6
    thank you for your response!! Can always count on this group! We only run into a few steam boilers a year, this one the boiler is running great but these old traps and vents are making a hell of a racket. I under stand the part going through the ceiling is the actual vent, and our supply house stocks the steam vent you mentioned so not problem there. It seems the noise is being generated from the trap itself, is there something that can be replaced with? Sounds like now that they are on natural gas it may be over kill? If we were to eliminate it would we repipe with a tee, connecting those lines together, and adding the #2 at the top?
    Thank you for your help!
  • Jamie Hall
    Jamie Hall Member Posts: 23,297
    If it's making a racket -- which it really shouldn't -- I'd be wondering if somehow steam is getting into the return which it serves. That would surely do it.

    In addition to the usual suspects -- including excess pressure (as @Gordo said, you're looking for less than 1 psi, preferably less than 8 ounces) -- I am a little wee bit concerned by what appears to be a wet return on the wall behind the boiler. What is the elevation of that pipe in relation to the operating water level in the boiler? If that pipe is at or even near the same elevation, steam could back into that we return and make all sorts of interesting noises.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England