thanks for this. It's definitely turned on but I'll try your suggestion. If this doesn't work do you think it will be worth looking at the pin in the trv...seen this mentioned on the site but not too sure what to do !
All of a sudden one of my radiators (downstairs) has stopped working. Both pipes are totally cold when system is on but all other radiators work ok. Have tried bleeding but no air came out. Does anyone have any suggestions other than calling out a plumber?