Low
d.25 on Vaillant Ecomax Condensing 600/800 series

Your boiler is currently focused on keeping an internal reserve of hot water ready for immediate use, which is a normal operational status rather than a fault.

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

Hot–water activation via warm–start clock

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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