Low
S.15 on Vaillant Home System

Your boiler is simply cooling itself down for a few minutes after heating your water, which is a normal part of its operation.

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

DHW mode: Pump/fan overrun

DIY fix possible

Wait 5 to 10 minutes for the boiler to finish its cooling cycleCheck that your hot water taps are fully turned offEnsure there is no 'constant' demand for hot water on your external controls

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Related fault codes

S.05View →S.14View →S.25View →

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