Right let me try to explain this problem, first of all the combi is about two years old and has been working ok up until the last few weeks.
When the control is only on "water only" sometimes you can hear the boiler trying to kick-in (clicking sound) but the actual burner doesn't kick in.
By turning the boiler off and turning it on sometimes works but oftens refuses.
Strangely by turning the switch on to "heating&water" it kicks in straight away however as the heating is on for hours (i cant stand beside it ) and the boiler heats up in periods i don't know for sure that sometimes is doesn't fire up in this mode.
It seems more apparent in hot water mode.
When the control is only on "water only" sometimes you can hear the boiler trying to kick-in (clicking sound) but the actual burner doesn't kick in.
By turning the boiler off and turning it on sometimes works but oftens refuses.
Strangely by turning the switch on to "heating&water" it kicks in straight away however as the heating is on for hours (i cant stand beside it ) and the boiler heats up in periods i don't know for sure that sometimes is doesn't fire up in this mode.
It seems more apparent in hot water mode.