DIY Doctor

Bang when thermostat reaches temp.

Postby greg555 » Fri May 23, 2008 10:45 am


When you set your thermostat to say 20 degrees and the temp is reached and the theromstat switches off... is it common to get a dull bang or thud from the heating network somewhere in the house?

This bang can be recreated when turning the thermostat up (above the current temp so the red LED comes on) and then turning it down (below current temp, the red LED turns off). The bang happes a seond or so after.

Any replies would be very appretiated ....

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Simply Build It

Postby plumbbob » Fri May 23, 2008 4:50 pm

If you have the type of heating system that has a hot water cylinder and header tanks in the loft, the possibility is the bang is water hammer caused by the motorised valve closing to shut off the hot supply to the radiators or cylinder.

If indeed this is the case, it may be awkward to solve and may involve replacing parts that are not exactly broken. This is not a major fault and will do no damage.
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Postby greg555 » Fri May 23, 2008 6:30 pm

Thanks for that reply!

I recently bought this new build house and it is still under warranty. I have already had a plumber out already and your reply I think goes along with his diagnosis. He said that it basically was supposed to do this? (make a bang noise and it was the design)

Is this common? If you had bought a new house would you put up with it? Is there always going to be some sort of noise?... ie is it more hassle than its worth to get it fixed (like floor boards etc getting ripped out)

thanks! :)
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