While you wait for answers, we may have found some information which could help you.
Click here for Diaphram Combi Hotpressure dropping on openning the hot water in my ravenheat csi 85 aboiler?
Faulty Ravenheat condensing boiler?
Faulty Worscester 35 CDi loosing pressure?
Central heating but no hot water?
how can i ignite the pilot light on a ravenheat boiler?
ravenheat csi 120 no hot water?