Hello! Can anybody help?? I've had one cold radiator downstairs for ages. All others up and downstairs OK. Tried bleeding it and air came out. Flushed it through several times and it seemed to be ok each time but as soon as the CH was turned off it would never come back on again. Forgot about it for a while. Several men gave different advice- thermostat, air lock upstairs etc. Brother in law came round today and did something to fix it whilst I was out and it was fine. Finally had heat in this bitter weather!! Now all downstairs rads are stone cold although upstairs OK!!! Have tried opening the lockshields a little more on each radiator trying to adjust but can anybody help please!!!!