We live in a bungalow and have a problem radiator that will not heat up at all. My OH has changed the thermostatic valve, tried bleeding it and has this morning taken radiator off and flushed it, still cannot get any heat from it, appeared to start heating up when he had bleed valve open then stopped when he closed it. Now nothing at all. The radiator was not full of sludge when he emptied it. We have a magna filter on system. All the other radiators are hot on the top and cold on the bottom! Can anyone advise please. Have asked 2 or 3 plumbers to look at it for us but no one seems interested.