BoilerFaultCodesAlpha d5 Fault Code
Also written as D5 — same fault.
The Alpha d5 fault code means: your boiler is simply displaying the temperature setting currently chosen for your hot water, rather than indicating an actual fault or breakdown.. It appears on 9 Alpha models in our database.
Technical description: Domestic hot water set point temperature °C
DIY fix possible
Wait a few seconds for the display to return to the default screenCheck your hot water dial to ensure it is set to your preferred temperatureNo further action is required as this is a status notification, not an error
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Alpha models that show the d5 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Alpha d5 fault code information on this page is sourced and cross-checked against the official Alpha service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026