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Drain Valve

mmc239 Member Posts: 81
If I open this valve and drain all the water out, will it take lol the water out of my steam radiator. I am getting a lot of water hammer and banging on my first floor radiators. 


  • mmc239
    mmc239 Member Posts: 81
    Or this?

  • Jamie Hall
    Jamie Hall Member Posts: 22,947
    If you open that valve it will take most of the water out of the boiler and any wet returns. It will not take water out of the radiators, because if the radiators and their pipes are pitched correctly, there's no water in there to take out. It all drains back to the boiler. So it won't help at all.

    If you are getting water hammer and banging, the most likely culprit is one or more to the steam mains or runouts pitched incorrectly, so a small amount of water pools in them. That water is then picked up by the steam and pushed along until it hits an elbow or something of the sort and it goes bang.

    So what you need to do is to look for pipes which aren't pitched correctly.

    There is another factor, though. If the boiler is running at too high a pressure, over 1.5 psi, water will be backed up into the mains, and that will cheerfully make a racket as well. So check the pressure at which the boiler is operating.

    Also another possibility, if these are one pipe radiators, is that the service valve where the steam comes into the radiator is not all the way open. This will trap a small amount of water in the radiator, and that can sometimes bang -- though that is more likely to gurgle. So make sure all those valves are open all the way.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 15,345
    edited January 2023
    The valve in the first picture Yes. But don't do it that is not the fix.

    You need to get a level and check all the radiators for pitch. If it is 1 pipe steam (1 pipe connected to each radiator) the radiators need to be low on the pipe end . You can raise the opposite end with a crowbar, blocks of wood and shims.

    You also need to check the pitch of all the steam lines both mains and runouts. The air vents should be checked/cleaned and or replaced.
    Do you have steam pressure in the boiler when steaming? How much? What is the pressure control set to? How is the water line , about half a glass and steady when steaming?

    Has the boiler been serviced including the pressure control pigtail?