Irregular tapping sound in one rad

[Sparky54]

Hi,

We have an 8' rad in one bedroom which has started to make a loud, irregular metallic tapping sound only when the pump is running. I have isolated the rad and it stops, and have held the rad against the wall mounts with no change. The tapping varies between twice a second to every couple of seconds and sounds a bit like a screwdriver being tapped inside the rad. It heats up OK and is hot top and bottom.

It's driving us nuts. Anything I can do short of replacing it?

 

[HERTS P&D]

Check where the pipework is rubbing against any joists or floor boards.

Andy

 

[ianmcd]

If it has a thermostatic radiator valve remove the sensor head and see if that stops it

 

[Sparky54]

The rad has the original simple lockshield (?) valves but thanks for the suggestion. The pipes under the floor do clonk a bit as the system warms up but that stops once it’s hot. This noise is continuous from cold all through the day. Only closing the valves or stopping the pump stops the irregular tapping noise. Thinking back the start of this could possibly coincide with me doing some work under the floor in another bedroom. Could the underfloor pipe work moving or touching something across the landing be amplified by the rad in this room? It is quite loud!

 

[Sparky54]

Turned out to be s simple fix really...! I tried closing and opening both valves a few times and it has stopped. The noise sounded like it was coming from about 1/3 along the rad so not sure what it was and why it has stopped. In fact the whole system seems to be running quieter !