Hello list, After trying 3 switches and testing everything else as my last post explained. I proceded to put my hands on all the pipes to see if they were getting hot enough,sure enough they were nearly burning my fingers. So I was just wondering as my fans work fine if I join the 2 wires on the otterstat,does it make any difference which way round the wires plug on the switch. Probably doesn't but I thought I would ask anyway. Cheers. Paul UK.It's a mystery,but if all else fails I guess its bleed or thermostat?