High
Flow on Grant Vortex Blue

Your boiler is not detecting water moving through the system, which is preventing it from firing up to provide hot water.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

If the boiler is not lit when a hot tap is opened this could mean there is a lack of water flow or possible flow switch problem

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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