what's my problem?

[Legume]

Had new valve power head and new dual channel clock supplied in November. Current problem is that when hot water timer comes on the central heating comes on too - even though I've set clock on CH to off position. It's summer (almost) & I need hot water in home but not accompanied by central heating. ???? HELP.

 

[lame plumber]

if all worked ok previously then its a wiring issue, if its always been like that a system design issue youll have to live with till you change the boiler probably, If you were ok before and youve a three port valve, then the valves probably seized and needed replacing when the head was changed