b24 High

Boiler Fault Code b24

Also written as B24 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code b24 appears across 3 boiler brands 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 water temperatures are the wrong way around, usually because the water is not flowing through the pipes correctly. (As reported on Vokera Pinnacle)

Pick your boiler brand for the b24 fix

Atag b24 1 model Johnson Starley b24 4 models Vokera b24 1 model

Source

Information for the b24 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 27 April 2026