My heating will not turn off, irrelivent of thermostat position, or service selection switch on boiler. The motorised valve in the airing cupboard is not opperating. How do I know if it is the valve that is faulty and not some other part of the system? The valve was replaced at the same time as the pump in 2004.
If it helps the valve has 4 wires going to the circuit board gray, orange, white, and another one (I cannot remember but it went to the motor and I think it was blue!).
Thanks for any help you can offer.