If your Thermostat radiator valve (TRV)  is not working, more than likely the TRV pin will be stuck. To fix this carry out the following steps.
Before you start, you should always make sure you carry out the following once the system has cooled down otherwise handling of some components when hot can give you heat burns.
- Set your TRV to the max. This helps in removing the TRV thermostat head, otherwise the lower numbers make it harder to remove.
2. Use grips to loosen the locking ring and remove the TRV thermostat head. Sometimes it will come off by hand, usually this means it was a little loosely tightened in the first place.
3. Use pliers or grips to push the pin up and down a few times, careful with some valves with bad design the pin may come out if you pull too hard. Most valves however the pin will not come out.
4. Apply some silicon grease to help the pin move more freely. Push down a few more times for the grease to spread.
5. In reverse order put the TRV head back on and set to original number.
Reasons TRV pins get stuck
The main reasons a TRV pin gets stuck is due to a combination of the water quality being poor / and or inactivity of the heating system. So as a general preventative guide, it is recommended to switch your heating on every month at least even during summer months. This stops deposits around valves and other vital equipment from solidifying and causing is to not work or worse break down.
Further Information
Some valves that are faulty are able to be serviced without draining down. See our article How to repair a thermostatic radiator valve (TRV) using a service tool Additionally, some valves have gland repair kits if they are leaking or faulty.
Disclaimer
In some cases, some TRVs may start to allow water to weep through, in this case usually it must be repaired by a heating professional. We accept no liability should this be the case, as it is a sign of faulty parts and degraded water quality.