How much does it cost to fix boiler error code 21E?

Typical repair cost for the boiler 21E fault is £120-250 including labour.

21E High

Boiler Fault Code 21E

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code 21E appears across 1 boiler brand and 7 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 returning from your radiators is too hot, which has caused it to shut down for safety. (As reported on Ravenheat HE 80/90 / 25-30s)

Pick your boiler brand for the 21E fix

Ravenheat 21E 7 models

Source

Information for the 21E 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