Low
d.25 on Vaillant ecoTEC Plus 840

Your boiler is simply indicating that the 'warm start' or cylinder heating feature requested by your thermostat is currently turned 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.

Technical description

Status of the requirement to reheat the cylinder or for the hot water warm start from the eBUS thermostat: off=Function deactivated, on=Function activated

DIY fix possible

Check your thermostat or boiler display settings to see if the 'warm start' or 'hot water comfort' function is disabledToggle the setting to 'on' if you prefer your hot water to be kept warm for faster deliveryNo action is required if you are happy with how your hot water is currently functioning

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