While you wait for answers, we may have found some information which could help you.
Click here for Boiler Home Heating PressureFerolli Optimax HE 31C expansion vessel change?
F40 fault?
How can i repair a noCN fault on my boiler?
ferroli plus 31c has a code b2 any ideas?
i have a ferroli combi boiler i have 1/2 the radiators working and 1/2 not ?
Replace a diverter valve?