Worcester 28cdi rsf heating on constantly

[zulubloke]

Hi
Had my boiler virtually rebuilt about a year ago by BG - new heat exchanger, diverted valve, pump.
Have an issue starts this morning in that the heating won't turn off. Hot water works really well, no loss of water temp, programmer (electronic, built into boiler fascia) set to off for heating, and heating temp control set to 'summer' of off position.

Have even turned all the radiator thermostats to minimum, but the boiler keeps turning on and feeding heat to radiators - it's getting a bit warm in here !

Yes, it's an old boiler, yes it has seen better days, but as I say, the major components are all pretty new.

Could this be an issue with the built in programmer?

 

[nickso]

Possibly.

If you are confident you can unplug it and see what happens.

 

[zulubloke]

Cheers for the reply - have unplugged it, seems to be working now as it should.
Thought might be the diverter valve or a thermostat, but removing programmer seems to have cured the problem. DHW works on demand, and CH fires up as soon as control knob is turned up, and only then.

It's now nice and cool again - will source a new programmer