On 2006-10-09 10:22:37 +0100, Drake said:


In a domesting hot-water CH system, What would cause a TRV to fail to
shut the radiator off when it is tightened down fully?

Thanks,

Drake

In normal operation it would either be crud or corrosion around the
valve seat or that the head has failed.

If your problem is that you want to shut off the valve to be able to
remove the radiator, then valves normally come with an extra plastic
cap that is screwed on in place of the head for this purpose.