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Banging Steam Supply Pipe

I have a two pipe steam system and every radiator is working fine except the one in the upstairs guest room. It is the second shoot off the furnace. The supply pipe will bang in the floor right below where the pipe comes out of the floor to get to the radiator. The pipe will get warm/hot about 4 inches above the floorboards but steam won't enter the radiator. I took off the return coupler to try and bleed the air through the radiator but that did not work. I also checked the steam valve to make sure it was open and that was working fine too. Any suggestions on how I can get this radiator functioning? Thanks


  • Jamie HallJamie Hall Posts: 10,279Member
    You are brave to take the return coupler off with the boiler running. If that had been the problem, you wouldn't have gotten air -- you'd have gotten steam and be badly burned by now.

    A pipe banging almost always indicates water trapped in the pipe. Question is why and where. Look for any horizontal, or near horizontal, lengths of pipe which don't pitch so that the water can drain back to the boiler in one direction or the other. First place I would be suspicious of would be that location in the floor which you mention.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Viggen1Viggen1 Posts: 6Member
    It has to be right under the floor where the steam supply comes there anything I can do to get the water out without taking up the floor?
  • IronmanIronman Posts: 4,964Member
    If the piping will allow, you MAY be able to get the sag out of the piping by raising the radiator and shimming it with some blocks of wood. Sometimes, 3/4" can make a difference.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • KC_JonesKC_Jones Posts: 4,093Member
    Viggen1 said:

    It has to be right under the floor where the steam supply comes there anything I can do to get the water out without taking up the floor?

    You aren't trying to get the water out, you need to prevent the water accumulation. The water accumulates due to improper pipe pitch.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
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