Low
S.11 on Vaillant Home System

Your boiler is currently preparing itself for a hot water demand by clearing the internal combustion chamber with the fan.

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.

What the manual says

Manufacturer manual

Hot water handling mode: Advance fan operation

From this model's manual
Verified against the Vaillant Home System installation & service manual, page 32.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check if your hot water timer or thermostat is activeMonitor the display to see if it changes to a heating or hot water code (starting with S.2 or S.4)No action is required as this is a normal operational status message, not a fault

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