Vaillant Diverter Valve

[Tom048]

I have a Vaillant 242 EH. The diverter valve moves to the right, followed by firing up of the boiler, as soon as the electric power is turned on, regardless of whether any hot-water taps are open.

The diverter valve only returns to the CH position when the electric power supply is turned off.

Any ideas as to why the diverter valve's doing this?

 

[kevplumb]

check the servo valve / water section first View media item 8355