Low
d.66 on Vaillant ecoFIT Pure 835

Your boiler has simply turned on its 'comfort' feature which keeps water pre-heated so it reaches your taps faster.

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

Activation of the warm start function for hot water

From this model's manual
Verified against the Vaillant Ecofit Pure 830 installation & service manual, page 31.
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

Locate the hot water temperature dial or buttons on the control panelTurn the dial fully to the right to enable 'Comfort' mode, or fully to the left then back to your desired temperature to reset the stateConsult your manual to toggle the warm-start function off if you prefer to save energy

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