Low Information
S.15 on Glow-worm Ultracom cxi

Your boiler is continuing to run its internal components after the heating or hot water has been turned off to safely cool down the system.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

pump / fan overrun

What causes this fault?

This is a normal function where the boiler continues to run its internal pump or fan after you have turned off your heating or hot water. It happens to move residual heat away from the heat exchanger to prevent the unit from overheating internally. Once the system reaches a safe, cool temperature, the components will switch off automatically.

DIY fix possible

Check that your room thermostat or programmer is turned down or off.Wait for 5 to 10 minutes to allow the cooling process to complete naturally.Check that at least one radiator valve (usually the bypass) is open to allow water to circulate.

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