Knocking noise when CH fires up

20 Oct 2008
Reaction score
United Kingdom
Everytime the CH fires up, there is a really loud knocking noise from the radiator in our room. I'm sure it is not the rad itself as I know noise can travel. It starts off quiet then gets louder, stops for a bit and the does it again. This happens for about 2 mins and everytime the thermostat clicks on for heat. This never happened this much since I had a new boiler fitted. Could it be because the new boiler is more poweful and it could be the pipes knocking? Don't really fancy having the carpet up and floorboards. Any other ideas?
Thank you
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Hi could be a trv if fitted to the radiator, if so try turning it off and then turn the heating on? Either that or could be travel from another part of the system! What type of boiler is it?? Combi, conventional? If conventional could be the port valve?
Hi, thanks for replying.
It is a system boiler. Have tried the TRV already and still happens. When I turn the end valve off though, the noise does stop. Could the new boiler be more efficient hence more powerful?
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Possibly due to the new boiler getting the heat round faster. The noise you hear is the metal expanding as it heats up, if its happening faster than previously then this could account for the noise.

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