My central heating only comes on when the HW circuit is turned on. With both off, if I turn on the CH circuit via the programmer, the motorised valve turns on and winds open but the boiler does not fire up. If I then turn on the HW circuit via the programmer the boiler fires up and heats HW and CH.
This used to work perfectly until recently. Nothing has (knowingly) been changed since it was working. There was a room thermostat but I bypassed this during renovations by joining both brown wires (L and SL) and insulating the earth and neutral. This was bypassed long before this fault developed.
I have a Potterton Suprima 60 boiler for CH and HW which are individually controlled by the programmer. I have a Myson motorised 2-port valve at the boiler (for CH) and same next to the upstairs cylinder.
The boiler and programmer are about a year old, the valves etc. were installed by the previous owner.
A picture of my boiler can be seen here http://84.203.164.145/boiler.jpgDoes this sound like an electrical or perhaps a PCB problem? The status light does not change colour when I turn on the CH alone. Another thing that's weird is the reset button doesn't seem to do anything, on my old boiler this used reset the boiler if I pressed it when running.
I'd rather not have to get my plumber out if I can avoid it so any advice would be much appreciated.
Cheers, Chris.