Heating system clanking

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    • #274240

      Just before the boiler starts up(most often), there is a loud clanking sound from our baseboard radiators. Hot pressure reads just below 20lbs., air seems to be gone from radiators. We’ve had some work done to system during remodeling by eliminating a radiator in a bath and replacing with underfloor Wirsbo piping, but clanking occurred last year, also, our 1st year in home. Radiators are not original in our 85+ year home. What can be done? TIA

    • #289427
      Harold Kestenholz

      A clanking sound just before the boiler starts indicates the clank is not from the boiler, but within the piping. The clank comes from a slug of water following an air space or a mechanical object striking. If the sound occurs from the water moving, the circulator must already be running. So there are some possibilities:

      1. The circulator is running all the time. The thermostat calls for heat in a zone. The zone valve opens permitting water to move against fittings. The zone valve end switch fires the boiler.

      2. There is a delay device for the boiler controls after the zone thermostat calling for heat starts the circulator.

      Others ….

      Whatever the cause of the delay, one clang may be because of the zone valve mechanism. Several clangs would be from water striking turns. The most likely cause is from bubbles of air separating from the heated water while still permitting a bubble to move ahead of the water column. Air is never totally eliminated from a system, but bubbles out and is reabsorbed as temperature and pressure changes in a sealed system. If the problem comes from gathered air, placement of components to prevent air gathering in locations and eliminating air at the locations is a cure.

    • #289428

      Can someone tell what to do about the banging radiator problem? My landlord installed a new furnace this summer and now living and working at home is a nightmare. The radiators bang and clank for a full 30 minutes every few hours so it is impossible to sleep or work. Landlord doesn’t know what to do either. Can anyone help? Email me at tracy5@netscape.net THANKS!

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