Low Information
S.10 on Vaillant ecoTEC

Your boiler has detected that you have turned on a hot water tap and is currently working to heat water for you.

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

Hot water demand

What causes this fault?

This code appears when the boiler's internal flow sensor detects water moving through the pipes after you open a hot water tap. It physically indicates that the internal diverter valve has shifted position to prioritise heating your water instead of your radiators. This is a normal functional message and does not indicate a mechanical failure or a breakdown.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Related fault codes

S.11View →S.13View →S.14View →

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