While you wait for answers, we may have found some information which could help you.
Click here for Combi Boiler Central Heating Home HeatingReplace a diverter valve?
How turn off heating in Ferolli Optimax 31c?
Ferroli Optimax HE31c a26 problem?
F40 fault?
i have a ferroli combi boiler i have 1/2 the radiators working and 1/2 not ?
Ferroli DOMIcompact F 30 D?