Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

radiators "snap" long after heating stopped

Well it also seems to happen in hot water radiators,..sometimes in a nice quiet room,..a radiator gives off a loud "snap" . These are with the big old radiators. I'm guessing this is something to do with the joints and the changes with the sizes when metals heat/contract. They also do it when heating but for whatever reason this seems more acceptable,..as you kind of expect it. But is this always to be expected? is there anything to do to fix this? Or at least reduce it,.


  • Zman
    Zman Member Posts: 7,569
    I suspect the sound is a result of thermal expansion.
    What water temp are you running? Are you using outdoor reset?
    Your rads will be quieter if you send them cooler water over a longer period rather than a quick slug of very hot water. They will heat more comfortably as well.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Jamie Hall
    Jamie Hall Member Posts: 23,273
    Your fundamental diagnosis -- that it is due to expansion and contraction with heat -- is correct. What to do with it... sometimes thin slippery shims under the radiator's feet works (cut from plastic milk jugs or something similar). Making sure the radiator is really sitting evenly on all four feet helps (again, a thin shim under one of the two light feet). Sometimes it may be where the pipes come through the wall...

    Sometimes... grin and bear it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England