I have a Vaillant ecotec plus which has been playing up. Sometimes when the heating is switched off I come down in the morning or even come home during the day to find the radiators are hot but the heating is switched off. I know about the warm start option and if I switch it off the problem stops. In winter this makes the water run warm but not hot. At times the only way to stop the boiler heating is to switch the warm start off. Is a valve faulty somewhere allowing the heating to come on when the warm start kicks in? This is driving me mad not to mention all the gas I am using. It seems to be worse when the heating is switched off and not on auto. Oh for the days of a nice simple non condensing boiler!