High
Constant RED on Grant Vortex Pro 15-26

Your boiler has detected that the water inside it is getting too hot and has automatically paused to prevent overheating, but it should restart once it has cooled down sufficiently.

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

Thermal protection function may stop the pump temporarily. Occurs if the fluid temperature increases further beyond the blinking red threshold. Remains constant red until normal temperature conditions return.

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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