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Steam radiator not heating

kevsul1 Member Posts: 28
Have a steam radiator at a school on the second floor not heating every other radiator is getting hot no problem with the gas boiler is building pressure opened the return trap cap right off the radiator got some air out of it that’s about it going back tomo what could be wrong with this radiator haven’t done much steam work suggestions appreciated


  • Jamie Hall
    Jamie Hall Member Posts: 22,885
    There is a return trap? Then it's two pipe. If you got some air out when you took the return trap cap off (brave man), it's quite possible that the trap is failed shut. Most traps can be rebuilt quite easily -- if need be, tell us what kind of trap. That's a good place to start anyway. Second if not much happened after that, check and see if the feed valve is open. I know that sounds obvious, but... Once you've done those two things, things get a little more complicated, and there are several possibilities.

    Make sure that the lines from the steam main to the radiator are all pitched to drain back to the main. Sometimes there can be a sag or a pipe which dropped, which can trap water and prevent steam flow. That usually creates a water hammer -- but not always.

    Make sure that the return line from the trap flows unimpeded to the dry return. Best way to check that is simply pour water into it with the cover off and element out -- the water should go away. But check also that the dry return is a dry return; if this is that odd radiator which goes directly to a wet return, it will need a vent.

    Still no heat? Check all the other traps on that return. One of them may be failed open, which will pressurize the return and you'll have poor or no heat.

    And so on...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • kevsul1
    kevsul1 Member Posts: 28
    The 2 way valve was stuck shut along with the steam trap thanks for the input