central heating operates when swiched to domestic hot water

[desmitch]

I have a combi. Chaffoteaux "Calydra aprox 6 yrs old.
the selector switch on the front of the boiler is switched to domestic HW but three days ago the central heatig operated with all the rads heating up and there was no domestic hot water from the taps or shower.
I have turned the boiler off but would be interested to hear if anyone has any idea what would cause this?

 

[Agile]

I think that your boiler has a motor driven diverter.

If so then the motor has probably failed. Its a black part with three wires on the connector.

If you remove the motor by taking out the spring clip you can see if its pin moves when you select heating and then turn on a hot tap. With the motor off you may get hot water again.

Of course there are other causes which a competent boiler engineer would investigate.

Tony

 

[desmitch]

Thanks Tony,
Checked the selector switch again this morning and all is working fine??
CORGI Plumber called and suggested that as it was now working it should be left well alone, though he did suggest that it may be the PCB.
(this guy actually fitted the boiler together with all the domestic and CH plumbing as the original "new build") .I'll keep an eye on it and call him back if it happens again.

 

[Agile]

Its possible that the diverter is sticking or the motor is intermittent.

Knowing what I do, I would be taking the motor off and see if the bottom is wet from a leaking gland.

Tony

 

[desmitch]

I'll check that out