Hello, I have what I have been told is a single pipe system; most of the radiators are the skirting board height type and quite old. The combi boiler is about seven years old and working and the pump is working, but most of the radiators aren't getting cold; the one normal height rad is getting warm. The one that works off the hot water system is working; it's a low height one. I can't find a motorised valve anywhere to test so suspect that a flush may be needed but that's a guess. I'm selling the house so don't want to replace the system. I would like a visit from somebody familiar with these systems. Can anybody help please? Geoff 07973 529183. Just realised that I may have misunderstood the meaning of the title of this forum and thus posted it in the wrong place; but can anyone help anyway?