BoilerFaultCodes P20 Low
Boiler Fault Code P20
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code P20 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is currently running at its maximum capacity to heat your hot water, which is a normal operational state rather than a sign of a fault. (As reported on Alpha Pro Tec Plus)
Pick your boiler brand for the P20 fix
Source
Information for the P20 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