Heating won't switch off when water is on

[NickJF]

I have developed a problem that when the heating is on and the water comes on the heating will not switch off.
It does not respond to the room thermostat at all.
The boiler is a Potterton Prima & Honeywell thermostat

Any thoughts / ideas gratefully accepted.

 

[Elkato531]

Looks like a motorised valve problem. The actuator heads on most models are available at plumbers merchants and most (but not all) don't require a drain down to change.

 

[b16kvv]

Before you go buying just the heads I would double check that the valve/valves themselves open and shut manually with the heads removed as if these are stuck then the whole valve and head will need replaced.

You can do this by removing the heads and using grips to work the valve open and shut.

Kev