High
9.i on Chaffoteaux Sterling FF

Your boiler is overheating because the internal filter that keeps the water moving is clogged with debris, preventing heat from being carried away 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

Excessive temperature rise across boiler - Return filter blocked

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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