Potterton Suprima 40 Boiler - CAN'T RUN CENT HEATING ONLY

[Pwhit]

Hi there (any help would be great)

I have a Potterton Suprima 40 Boiler controlled by a Landis & Staefa RWB9 Programmer / timer.

Both CH and HW work perfectly, but all of a sudden I CANNOT SWITCH ON JUST THE CH ON BY ITSELF. (which you have always been able to do from when it was installed from new approx 7 years ago).

I have tried "rebooting" the boiler and "resetting" the programmer (including removing the battery) but the CH will only come on if the boiler flame is already being fired by the request for HW.

When you press just the CH button, the programmer lights up as normal, but the boiler doesn't actually fire up and come to life.

Any ideas any experts out there?
Is it a poss programmer fault? (the signal not being sent to ignite the boiler) (in which case I could swap + fix it myself)
Or is it more likely an electronics fault in the boiler itself?

Many thanks for any help
Paul.

 

[ollski]

It will probably be the synchron motor in the motorized valve head not having enough power to motor all the way across, but will sit in mid position with the hot water on aswell. It could always be a swollen ball in the valve itself though.

 

[Pwhit]

cheers for that

sounds like I need a boiler engineer then.

Oh well, never mind, at least it's still functional at the moment, but for how long is anyone's guess.