I had a heating engineer out for 2 1/2 hours on Friday trying to find the cause of the problem and needless to say he thought the motor needed replacing but it is fine.
The question I had was what triggers the boiler to start up if the microswitch wire on the central heating motorised valve unit is deliberately capped off with a junction box?
The engineer and myself both looked for a stray wire to attach to the other side of the junction box to no avail.
Seems every issue I ever have with houses I own is a 'non-standard' setup.
Thanks in advance,