Radiator stays cold when temp guage is put back on

dvtrv

Hi,

Two of my radiators stopped working so I got an engineer in to resolve which he did.
Turned out the pin in each was stuck.
He showed me just for my curiosity.

Daft me, after he had gone, decided to unscrew the British Gas thermostat valve to see if I could do it.

The valve in push able down and is firm when doing so.

Problem I have is when I rescrew the thermostat controller over the pin the radiator doesn't get warm but does when unscrewed and left off.

I tried it turning guage to nil and also on setting 6.
I've pushed the valve in and it springs up each time. I've also sprayed and swisted setting from nil to 6 and it moves freely.

Can anyone advise what is wrong or what I've done am doing wrong please?

Thank you

SGM1

The TRV head is faulty I would guess. If the rad heats when the head is off it must be fine. The head could be stuck in the off position, when you put it back on can you feel the pin pushing down?

dvtrv

Thank you everybody I've bought new thermostat and it's ready to be fitted.