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S.17 on Glow-worm Ultracom 2 HXI

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

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 overrun

What causes this fault?

This occurs when the boiler has finished heating and needs to dissipate residual heat from the internal heat exchanger. The pump continues to circulate water to prevent the internal temperature from rising too high after the burner has turned off. It is a normal safety function designed to protect the boiler's components from thermal stress.

DIY fix possible

Wait for several minutes as this is a normal part of the boiler's cooling processEnsure at least one radiator with a manual valve is fully open to allow water flowCheck if the boiler eventually moves to a different status code like S.0 or S.30

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Related fault codes

S.07View →F22View →F24View →

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