High
F24 on Glow-worm CXi

Your boiler has detected that the water returning from your radiators is dangerously hot, which usually means the water isn't circulating around your home 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.

What the manual says

Manufacturer manual

Central heating return temperature is greater than 90°C

From this model's manual
Verified against the Research Cxi And Gas Valve 157149 installation & service manual, page 39.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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