BoilerFaultCodes A26 High
Boiler Fault Code A26
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code A26 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected that the main heat exchanger is getting too hot, likely due to poor water circulation or a buildup of debris, and has shut down to prevent internal damage. (As reported on Ferroli Bluehelix Tech RRT 24C)
Pick your boiler brand for the A26 fix
Source
Information for the A26 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 7 July 2026