While you wait for answers, we may have found some information which could help you.
Click here for Pump Combi Boilerravenheat csi 85(t) 780 series red light flashing?
Central heating but no hot water?
ravenheat csi 120 no hot water?
Ravenheat CSI 85 Red Light?
minimal hot water ?
ravenheat csi 85 b (t) hot water no central heating?