While you wait for answers, we may have found some information which could help you.
Click here for Boiler Glow WormI have a 30cx glowwarm that is showing F4 as fault.I have no hot water?
GS 24i junior boiler timer broken?
Home heating systems?
I have moved into a flat am dissabled carnt get heating on unit flashing F1?
Which way to turn slotted screw to adjust water pressure up on a glow worm ?
BMU error code?