Boiler Fault Code Hot water demand indicator

Also written as HOTWATERDEMANDINDICATOR — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code Hot water demand indicator appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is working exactly as it should and is simply confirming that it has received your request to heat water for your tap or shower. (As reported on Vaillant Turbomax 242/282 1E)