High
F26 on Saunier Duval Semia Condens F30 E

Your boiler has detected that hot water is not moving through your radiators properly, causing the system to get too hot inside and shut down as a precaution.

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

Maximum delta temperature (flow - return). Water circulation fault. Check central heating flow and return connection

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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