F5 Low

Alpha F5 Fault Code

The Alpha F5 fault code means: your boiler is simply cooling itself down after use, which is a normal part of its automatic shutdown process.. It appears on 4 Alpha models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Post circulation in progress. Pump operating after a request for domestic hot water or central heating in order to cool the primary circuit.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Alpha models that show the F5 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Alpha F5 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 27 April 2026