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Cast iron baseboard insanely loud. SAVE ME

JSDNJ Member Posts: 13
Hello all,

My home is full of cast iron baseboards in a 3 zone hydronic system. I have bled the zones as a first attempt, but the issue remains.

When the system kicks on, I get loud,continuous banging. Wakes me up nightly. It sounds like a loud crack or snap. Often multiple in succession.

What do I try next? My guess is it's thermal expansion, but I'm thinking maybe the cast iron is binding against the wall, floor or 50 years of paint on it?

Any suggestions? I'm about ready to tear it all out for fin tube.


  • Paul48
    Paul48 Member Posts: 4,469
    Put strips of plastic milk carton between the floor and the baseboard. Make sure there's clearance around any pipe that penetrates the floor.
  • Tinman
    Tinman Member Posts: 2,806
    I'd look at the pipe floor/wall penetrations too. You should have 1/4" clearance or so all around the pipe. The baseboard is actually anchored to the wall, or should be, so I doubt its the wall or the floor.
    What water temperature are you operating at?

    Steve Minnich
    EBEBRATT-Ed Member Posts: 14,455
    Cast iron is better than fin tube don't tear it out. Check the water pressure in the boiler and the water temperature.

    pressure should be between 12-20. Temperature about 190 maximum

    Could this be making steam??
    JSDNJ Member Posts: 13
    I have the boiler down around 155. The baseboards are screwed to the wall but they have little legs on each end that rest on the floor. I'm thinking they might be the culprit but it sounds like it's coming from inside the baseboard sometimes.
    JSDNJ Member Posts: 13
    Well I pried the baseboard up a bit and slipped a putty knife under the legs to separate them from the floors. Then I slid strips of plastic under them. So far it worked and the banging and cracking is gone.

    I don't want to get my hopes up yet, but it sounds like it's fixed. Thanks!!!