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2 pipe steam system not heating

I have 7 radiators on a 2 pipe steam system not heating. Don't know if traps are bad or clogged. If 1 radiator is plugged all others work fine. Please give input towards solution. Thanks in advance.


  • dopey27177
    dopey27177 Member Posts: 887
    Hard to tell whats up, insufficient information.

    So I will try it this way.

    1. are there vent valves on the radiators, if so remove them and plug the tapping.
    2. What is the steam pressure in the system? should not exceed 1 psig.
    3. If one radiator when open causes a no heat condition it means the the steam trap has failed in open condition. That causes the return side of the piping to pressurize. When the both sides of the piping system reach equal pressure a no flow condition occurs. Steam can only travel to the zone of lower pressure which should be the return.

  • Jamie Hall
    Jamie Hall Member Posts: 23,324
    Well.... that's a bit vague. Is it one specific radiator which you plug which allows the others to heat? Or is it if you pick a radiator -- any radiator -- and plug it, the others heat?

    And... how are you plugging the radiator?

    Main vents, particularly on the dry returns? Operating pressure? One main and one dry return, or several of each?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England