Low Information
S.20 on Vaillant ecoTEC plus Regular

Your boiler is perfectly healthy and is simply letting you know that it is currently preparing or providing heat to your radiators or hot water cylinder.

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

Warnstar demand

What causes this fault?

This status occurs when the boiler receives a signal from your thermostat or timer that the house needs heating or the hot water tank needs warming. It indicates that the internal controls have successfully registered this request and the boiler is now initiating its firing sequence. It is the standard starting point for normal operation rather than a mechanical failure.

DIY fix possible

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

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Related fault codes

S.24View →

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