Low
d.25 on Vaillant ecoFIT Pure 835

Your boiler is currently reporting whether your thermostat is asking it to pre-heat your water or keep it 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

Status of the requirement to reheat the cylinder or for the hot water warm start from the eBUS thermostat

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

No action is usually required as this is a status code, not an error.If you want to disable this feature to save energy, check your thermostat settings for 'Warm Start' or 'Pre-heat'.Ensure your thermostat is calling for heat or hot water as expected.

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