How can I tell if my trv IS broken?

[Swoph]

I have one cold radiator in my house, I have already fixed a few by lubricating the pins on the TRV and that worked a treat but this last one is giving me hassle. The pin goes in and out when I use pliers (gently of course) but when it goes down it doesn't come back up automatically, its too stiff. (It has a westherm thermostat if that is relevant). Anyway, so I've just bought a new radiator valve (a lockshield one, I don't care about the thermostat - I just want a working radiator!). But before I start draining the system and so on, i was wondering if there were some tests I could do to make sure it IS the trv which is the problem, the last thing i want is to go through all the palava of changing it only to find it STILL doesn't work!

If the pin is UP, even if the thermostat isn't attached, should the radiator still heat up? If it doesn't, does this mean it isn't the TRV?

Thank you!!

 

[turbofan]

first check lockshield valve is open.trv is probaly seized internally,to try to unseize it i would get all other radiators up to temperature,turn off all hot radiators.
turn boiler off at boiler stat or on off switch ensure pump still pumps.
you are now trying to force maximum pumping pressure through this radiator.
gently tap pin down with a small hammer and also tap side of valve body.gently.
if it works then dont refit trv sensor.
good luck.

 

[Swoph]

turn boiler off at boiler stat or on off switch ensure pump still pumps.
you are now trying to force maximum pumping pressure through this radiator.

Should I turn the boiler back ON after turning it off? Also..how do i ensure the 'pump still pumps'?

I have a gas combi boiler...probably should have mentioned that!

Thanks so much for your help

 

[turbofan]

which boiler

 

[Swoph]

The boiler is an APLHA 240E