While you wait for answers, we may have found some information which could help you.
Click here for Problem 18 Monthspressure dropping on openning the hot water in my ravenheat csi 85 aboiler?
ravenheat csi 85(t) 780 series red light flashing?
how can i ignite the pilot light on a ravenheat boiler?
Central heating but no hot water?
Faulty Worscester 35 CDi loosing pressure?
ravenheat csi 85 b (t) hot water no central heating?