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one big thud from a radiator

You guys have been so helpful thus far in coming up with solutions for various issues. Steam systems are so sensitive!

Anyway, the latest thing we're trying to figure out is that we have this one radiator that makes one big thud when the whole system starts to heat up. You kind of feel it when you're in the room. I don't think it's water hammer. It doesn't sound like metal on metal. I think it might be expansion? I was thinking of putting some silicone or hdpe around the hole where the pipe comes out of the floor and then maybe under the feet?

Comments

  • BobC
    BobC Member Posts: 5,502
    Try cutting up a plastic milk jug and use that in the spots you called out. Look below and see if the pipe feeding that rad can rub up against anything and work some plastic in there as well.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • gerry gill
    gerry gill Member Posts: 3,078
    try to figure out where the steam is when it occurs. But as you suspect, it may be what my shop calls a 'drag and release' noise but hopefully not sideways thru a joist hole.
    gwgillplumbingandheating.com
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • Sooo this is what I've found. The radiator the thud has been coming from is on a board because we raised it to fix a water hammer problem. This week I've found that the radiator and board that it rests on have moved a bit. The radiator wound about askew from the wall. Would this be 'drag and release'? What can I do about it?

    Anyway, for now I've straightened it out and pushed the board back against the all. I also placed some plastic around the pipe coming out of the floor to see if that helps.
  • We're still getting the thud. I think we're going to try and apply some plastic in the basement around the pipe that goes to that radiator since we have access to the pipe.

    Also, there aren't any supports for the pipe in the basement holding it in place. Would that help with any expansion shifts?
  • Fred
    Fred Member Posts: 8,542
    How long is that run? It is possible that that pipe shifts a little without any supports. Does that unsupported pipe have a sag in it (bowed in the middle)? If so, what you are hearing could be water hammer that resonates into the radiator.
  • The run is about 10 feet. We raised the radiator because the pipe was tilted the wrong way due to the house settling (its over 100 years old!). There was a huge water hammer before, but the clanking went away when we did this. Perhaps now the run is pressed against the floor boards somewhere along the way.

    I'll check it out. Maybe we can put in a support in a couple of places to hold the pipe in place.