worcester 24cdi redlight flashing?

i have a worcester 24cdi with the red light flashing intermittently on hot water & heating demand,this can happen any time & sometimes goes 4/5 days without failing,no set pattern to it,but when i reset it everything fins for a while tilll mayb the next demand..any ideas anyone?

andy

andy, September 2006

poss missing flue restrictor has this been a problem since new.

paul, October 2006