after several years of problems,2 pcb boards,pcb repaired twice since [dry joint problems] new upgraded pcb fitted ,to end the problem,it now only works the hot water system,but not the heating,any ideas how i can check out which part of the system is not operating correctly?which colour wires have what function and what current? how can i bridge out thermostat? what can i do to check out diverter valve?

reg, November 2010

Turn on the heating on the clock, and turn the water off, you should be getting 240v on the diverter grey wire, and 240v on the diveter white wire.
The diveter should motor across to the heating side firing the pump and boiler.

Carefree, November 2010