Boiler timer won't provide independent heating/hot water - Drayton LP722 British Gas UP2

[jellon]

Hi,

Basically, when I switch on heating, the timer is switching on both heating and hot water (to a tank). Both lights come on.

Oddly - I can switch on hot water independently - without triggering the heating.

I have taken off the timer and ensured it is switched to Independent control and Gravity system. Also the 3 way valve, heater thermostat and heating pump are all functioning as they should.

I have seen posts that suggest poor contact with the wall plate could cause issues like this - it is a much older back plate.

Does anyone have any other suggestions, or know of this issue?

[ericmark]

Three port valve not normal used with gravity system. With gravity normally you can have DHW in it's own, but not CH on it's own. Called C Plan.