need help - biasi 24s central heating on constantly

[alis]

when the control is swithced to c/h & hot water my central heating comes on automatically (although the slider is set to off)

if the control is set to hot water only my central heating still comes on

it does not matter whether the central heating slider is set to on, off or timed is still comes on automatically.

..basically mycentral heating runs 24/7 (unless i turn the boiler off via the plug or boiler control)

what can the problem be?

i have replaced the diaphragm and gas valve in the past 12 months to solve other problems i had.

any help would be much appreciated.

thanks

 

[Agile]

The hot water flow demand switch is stuck at "on".

This will either be because the gland has leaked water into the switch OR because the pin has jammed.

Both these causes are likely to be caused by dirt in the system.

Since the gas valve has to be removed to access these parts I cannot give advice on how to do it to anyone who is not CORGI registered.

We charge £127 for replacing the switch and gland and checking the operation and setup of the boiler.

Tony