Medium
Primary flow switch operated on Alpha CB 240 / 280

Your boiler detects water movement even when it is not supposed to, which often means an internal valve is stuck or a sensor is misreading the flow.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description

Follow section 'C' fault finding

Engineer required

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

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