F64 High

Boiler Fault Code F64

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code F64 appears across 3 boiler brands and 11 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler’s internal computer brains are struggling to talk to each other, meaning the system cannot run safely. (As reported on Glow-worm Ultracom 35 Store)

Pick your boiler brand for the F64 fix

Ferroli F64 1 model Glow-worm F64 8 models Heatline F64 2 models

Source

Information for the F64 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026