worcester 350 hot water works no central heating

[freak]

Hi all, ive got a problem with a worcester 350. the hot water is working but no central heating,it started to malfunction about three weeks ago intermitently. ie the radiators would go cold but the boiler lights would still be on, pumping but without gas.
There was some air in the system that I got rid of including undoing the cap on the release/ bleed valve.
Also shortly before heating packed up all together the pressure went up to 3 bar.
I am more than capable of using a multi meter so any advice would be greatly appreciated.
mother board and control board were replaced last winter.
thanks in advance.

 

[corgiman]

probably a naffed central heating pump, I think its the one on the left

 

[freak]

Hi the the heating is now working on and off again sometimes works for an hour or sometimes up to four hours before stopping,again we can still get hot water.Do you still think it could be pump?Many thanks,we have now taken to getting our coal fire working.

 

[bengasman]

Lower the pressure to 1 bar cold. if it goes up a lot when warm, expansion vessel is dead or flat. Could be a sensor not working, what setting is the boiler on? Possibly diverter or micro switch stuck. Bit hard to say with an intermittent fault unless you know what happens when

 

[freak]

Hi , thanks for reply.I have raised the pressure to 1 bar it only moves a fraction when warm.As regards the heating settings we only ever switch to heating on when we need it(as we cant read digital display to set to timing etc).heating is still switching off and also the hot water goes off as well now but not as often as ch.Its also getting much harder to activate boiler we are now having to switch it off at the mains and relight ,as for when pilot light is out etc.
Once again many thanks