worcester 30cdi e9 fault

[pipefitter]

Hi all ,i have a customer with a worcester 35cdi combi,which locks out randomly & needs resetting. Temp on boiler goes to about 63 then locks out press reset temp falls down to 40's then boiler fires but Like its on very low demand(hot water is fine)when the boost button is pressed it goes onto full output for around 10 mins then trips out displaying e9 code,,I've checked fuses on pcb ,flue limit stat,primary sensor & overheat stat ,checked the flue ,pump is running but could it be running to slow? Any help much appreciated

 

[aggis]

E9 is that the safety temperature circuit has tripped. Starting with the flue limit & flow limit.
If it's locking out at 63 I'd try replacing the flow 1st then flue.
Take a look at the Worcester site, there's a very good booklet available, Greenstar Engineers service booklet.

 

[pipefitter]

You don't think its anything to do with the pump then?
Thanks for the reply

 

[aggis]

It's possible, but if it's locking out at 63degrees prob the o/h, would have thought the temp guage would go sky high if was pump. Also o/heats will be cheaper to try.