I have a Potterton Suprima 60L Boiler, After 3 years trouble free operation, the hot water advance now fails to stay on. The central heating function still works fine, but the heating advance trips out after initially firing up. The AC supply is present, the circuit board joints on the large connector pins looked decidedly poor and hence have been reflowed. The temperature control potentiometer works fine and it's resistance varies over it's range.
I suspect either the overheat thermostat (404517 which measures 0.1 ohm, which i presume is ok) so the more likely fault has to be the temperature sensor (840516 which fluctuates in valve from approx 0.35Mohm to 0.56Mohm over the range of the temperature control pot). I would appreciate any comments or suggestions from people who had experienced a similar fault. I assume that using Dow Corning 340 Heat Sink Compound will be suitable to use as a conductive compound.
