As this is a slightly different topic, I thought I'd start a new thread.

After me thinking that the radiator was noisy, but subsequently found
that by turning the trv slightly, the noise or vibration stops.

Now, I have found that just by lightly squeezing? the body of the trv
the noise/vibration stops. Also when doing this I could here a slight
hissing noise either in the pipe or trv, and when a slightly turned the
trv control, both the noise or vibration, and the slight hissing stopped.

I also found that the slight hissing sound changed in sound level as I
turned the trv control, and the more I turned it the sound decreased to
a stop.Conversely the more I turned the trv control the other way, the
hissing sound became more pronounced or louder.