Water heating continues even though programmer is off.

[ChuckD]

Water heating continues even though the programmer hot water channel is switched off. The only way to stop it is by switching off the boiler (Valliant).

 

[Best]

Plenty of threads about similar problems on here.
Motorised valve most likely.
Nearly always it is just the head (elecrical bit) that is faulty, but occasionally the m.v. body has a seized spindle which will prevent the valve turning off.