Worcester Combi Boiler

[chrisgolf2]

I have a Worcester combi boiler & since engineer gave it its annual service last week the central heating comes on when the hot tap is turned on! Have checked timer settings

[AKMild]

Could be a sticky three-way valve. Get the engineer back!

[BRIGHT SPARK]

Chris...a distant diagnosis suggests a diverter problem..as AK advises.

[Dennisuk]

Sounds like the diverted valve sticking.I have a very old Valiant boilet that nwas doing the same about 12 years ago, I just moved it with a heavy screw driver the sprayed a little wd 40 no trouble since. But I don't know your boiler my diverter I think is hydraulic not electic but if I am wrong I stand corrected.