High
DHW PUMP Fast flash on Grant Vortex Pro 15-26

Your boiler is having trouble sensing the temperature of your hot water supply, which means it cannot heat your water properly.

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

Check DHW ‘store’ thermistor connection to PCB. Replace ‘store’ thermistor.

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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