Low
d.21 on Vaillant ecoFIT Pure 835

Your boiler is simply indicating whether the pre-heat function, which keeps water hot for faster delivery to your taps, is currently turned on or off.

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

Status of the warm start for hot water

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 30.
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

Navigate to the boiler menuLocate the 'Warmstart' or 'Comfort' settingToggle the setting to 'on' or 'off' depending on your preference

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d.20View →d.22View →

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