Intermittent Radiator Problem

[Bink85]

Hi, I've had a look through the site and Google, but have been unable to find an answer to my problem.

Whenever I turn central heating on, radiators heat up as they, however after a varying period of time, usually after a minimum of a couple of hours, the radiators will all suddenly turn off, and gradually go cold, without turning on again until the heating is turned off, and then on again. Has anyone any idea what could be causing this?

If it helps, boiler is a combi, Worcester bosch greenstar, approx 3 years old.

Thanks in advance

 

[calorific]

Roomstat set too low?

 

[Bink85]

I don't actually have a seperate roomstat, just the controller

 

[Bink85]

Anyone any ideas? It's been on about 3 hours this evening before deciding to turn itself off again

 

[mcmoby69]

what controller do you have, is it a wireless one by any chance?

 

[MANDATE]

As I understand it with a combi, you can't have HW and CH at the same time.
Opening a HW tap operates a diverter valve to provide a different circuit.
It could be that after this action the diverter valve is not fully returning to the CH position.
When the diverter reaches the end of its travel it usually operates a micro switch to light boiler, so if it is sticking and not reaching the end of it's range the micro switch does not switch boiler on again.
I doubt if the boiler runs continuous for 3 hours but the refusal to re start may well coincide with the using of a hot tap and movement of the diverter valve.
No doubt you will get advice from those in the trade, but that's my line of thought

 

[Bink85]

That does seem possible to be honest. They were fine the other day and I noticed they'd turned off after I went to to the loo, so it would make sense. Is this something that I can fix? Or would it have to be an engineer?

Controller is a wireless, strangely, old fashioned one with the twisty dials and little day/night pegs