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Can I drain water from a steam radiator?

Pat_M Member Posts: 16
One-pipe steam radiator. Banging like mad this season and spitting from vent. I replaced the vent. It's pitched correctly (I even just tried raising it a hair more).

I assume this is a trapped-water issue? If so, can I drain it? Other thoughts? Thanks.


  • ethicalpaul
    ethicalpaul Member Posts: 5,735
    Draining it is not going to help. Any low spot will collect water again with the next heating cycle from the condensed steam.

    You must find any low spot in your piping that can collect water and modify it so there is no low spot for water to collect.

    It might be in the pipe just below your radiator, not the radiator itself. You can try gently lifting both sides of the radiator in hopes of removing a possible sag below it. Always use a level by the way, the eye lies.
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
    EBEBRATT-Ed Member Posts: 15,624

    What @ethicalpaul said is correct. It will only collect more water. Something is not pitched right.
  • Steamhead
    Steamhead Member Posts: 16,899
    Either that or the shutoff valve is broken, or not opened all the way.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    STEAM DOCTOR Member Posts: 2,010
    Have you checked boiler water level? How is boiler piping? Does boiler water jump around while boiler is firing? What is the history? When did problem start? Any changes anywhere in the season?
  • Pat_M
    Pat_M Member Posts: 16
    ok - tried to run heat last night. Hammering like mad -- REALLY loud. Rad is tipped correctly (checked with level). Noticed that pressure gauge on boiler was at about 10! So, shut everything down. This AM, I tried adjusting the pressuretrol. (I had some recent work done...just on piping, but don't know if he messed with pressure at all). Anyway, it didn't seem out-of-whack, but I ensured it was set to .5 on cut-in and 1 on cut-out (white dial at max counter-clockwise). Fired it up and pressure was creeping up to 8+. So I shut it down again. Bad pressuretrol maybe?

    We've been in house for 15 years. Routine adjustments/fixes now and then -- never hammering like this.


  • Jamie Hall
    Jamie Hall Member Posts: 23,442
    Has the pigtail for the pressuretrol ever been cleaned or even checked? They can and do clog, and when they do the pressuretrol can't see the boiler pressure -- and can't control the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Pat_M
    Pat_M Member Posts: 16
    never had anyone look at the pigtail (as far as I can remember). Thanks for the idea - I'll add it to the list for service tech.