BoilerFaultCodesGlow-worm S.10 Fault Code
Also written as S10 — same fault.
The Glow-worm S.10 fault code means: your boiler is not showing an error, but is simply indicating that it is currently operating to provide hot water to your taps or shower.. It appears on 9 Glow-worm models in our database.
Technical description: domestic hot water demand
What causes the Glow-worm S.10 fault?
This code appears when the boiler’s internal sensors detect that a hot water tap or shower has been turned on somewhere in your home. It isn't a fault, but rather a status message confirming the boiler is successfully diverting energy to heat your water. If you see this when no taps are running, it could indicate a dripping tap or a minor internal sensor issue.
DIY fix possible
Check if any hot water taps are slightly open or drippingMonitor the display; the code should change once you turn off the hot waterNo action is required if hot water is currently being used
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Gas Safe Register →Glow-worm models that show the S.10 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm S.10 fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026