While you wait for answers, we may have found some information which could help you.
Click here for Flow Switch Problemboiler will not turn off (only manually)glow-worm micron 80ff?
how to find a fault?
Glow-worm 30cxl?
Loud clanging/Glow-worm Boiler?
Glow-worm micron 60ff boiler niosy ?
water from taps is boiling hot?