High
45 on Alpha Intec 50CS

Your boiler has detected that the water leaving your heating system is returning much cooler than expected, suggesting a blockage or a failure to circulate heat 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

High flow and return temperature difference detected - The temperature difference between the flow and return sensors is too high

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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