Low
S.20 on Heatline Centurion 25

Your boiler is currently preparing to fire by checking the water circulation, which is a normal part of the start-up process.

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

Pre-run pump

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

S.21View →

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