worcester 350 combi heating luke warm

[dobo666]

never worked one a worcester 350 before its the one with 2 pumps and no diverter valve.
hot water works fine heating fires up on demand but keeps cutting out at a low temperature so rads are luke warm,pump is fine and system is clear as sometimes it will work and rads heat up fast. any ideas??

 

[jtsplumbing]

Are you sure that heating pump is working and not just making a noise ?

 

[dobo666]

yes that was my first thought i swaped id for a pump that i know is working. it seemed like a circulation problem at first but i think the boiler is actually cutting off at a low temperature even though the dial is on max

 

[diamondgas]

Possible c/h sensor fault or snapped selector knob spindle perhaps? Been a long time since I've worked on one TBH

 

[dobo666]

what sensor could it be i have no manual, its not the spindle as iv operated it from the board side to make sure

 

[diamondgas]

The central heating temp sensor.

I think this boiler runs for a period of time on low fire before modulating up to whatever it's been set at! I'd have to look at mi's but does this boiler have the two speed fan too?

 

[diamondgas]

Just got hold of the mi's dobo... You need to be checking gas pressures etc for modulation and voltages at the fan .... Also maybe resistance of ch sensor .... Not for the open forum here. If you're gas safe registered then you need to register with the site for the GSR's only here http://www.ukplumbersforums.co.uk/g...ate-gas-safety-registered-plumbers-forum.html