just started problem where does not fire up when turn on hw tap. sometimes if turn tap off and then turn back on it will or if i flick the central heating/ water or on off switches then turn on will be ok. or if i turn on central heating then hw is fine. does this sound like diverter valve or circuit board problem?

mikedav, October 2011

It sounds like neither diverter or circuit problem, simply sounds like a wearing diaphragm in the water section not lifting the servo valve to make the m3 microswitch.
Get the diaphragm changed before looking elsewhere.

Carefree, October 2011

Change diverter valve

Ltd, October 2011