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steam hammer - but only after thermostat was messed with

First time homeowner and poster here. I had a housewarming party at my 1890s victorian that still has old steam radiators, and some jerk cranked the thermostat to 85 (I normally keep it around 65-68).

NOW I have steam hammer when I never did before (owned house since July). I cannot overstate how loud the sounds are. Right now I am keeping the heat low so the clangs don't sound as much, but what kind of fix do I need to address steam hammer clangs that were seemingly caused by one misuse of the system?

Many thanks.


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Sudden new water hammer

    First, are all the radiator inlet valves fully open?

    Can you feel, and hear the exact location of the hammering (supplies, returns, radiators, boiler).

    Are the steam supplies, and boiler header insulated with 1inch fiberglass? Take pictures of the boiler piping and post them here.

    I am not sure of the connection between a onetime thermostat adjustment, and the noise you describe. It was a problem waiting to happen.--NBC
  • Jamie Hall
    Jamie Hall Member Posts: 22,934
    Also, while you are at it...

    check the pitch of all the pipes you can find, to make sure that they are able to drain out properly.

    It is possible that the very long run from cranking the thermostat up allowed more condensate than is normal for your use to accumulate in a low spot somewhere.  This will cause an amazing amount of noise...  as NBC says, an event waiting to happen, but having happened -- with some persistence it can be made to not happen again!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Poto
    Poto Posts: 12
    Not a pro, but this might help

    This happened to me, not so long ago.  Cranked up the Thermostat because we had guests coming over and I like to keep a pretty cool (downright cold according to the wife) house. 

    Turned out the extended cycle time threw enough steam into the system that the auto-water fill kicked in.  Once all the condensate got back to boiler for the next cycle (Thermostat now @ usual temp), water level was @ full site glass, creating wet steam and water hammer.

    Since it was time for a blow-down anyway, drained the system, filled system to half full and hammer went away.
  • Noel
    Noel Member Posts: 177

    The big load could have flushed a wad of crud together and it now holds water back from flowing smoothly down the return piping, causing steam and water to mix loudly.

    Could be a coincidence, timing wise, but the solution won't care what caused it.

    Something is holding water back, someplace.

  • mchouse
    mchouse Member Posts: 2
    maybe its ok now?

    I have people renting rooms, so one issue was that not all valves were open.

    They're all open now and the last episode of clanging was much less loud and long in duration than previous. Is it possible this was the only issue and the problem is working itself out? All gauges on the main unit seem normal, i can post a pic later
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