Low
S.21 on Vaillant ecoTEC plus aquaPLUS

Your boiler is currently busy heating up the internal hot water storage tank so you have plenty of hot water ready for use.

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

Fan running (store charging)

From this model's manual
Verified against the Vaillant Ecotec Plus Aquaplus installation & service manual, page 38.
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

No action is required as this is a normal status message, not a fault.Wait approximately 15-20 minutes for the 'S' code to clear once the tank is hot.Check that your hot water temperature dial is set to your preferred level.

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