Low
d.17 on Vaillant ecoTEC plus System

Your boiler is currently set to monitor the warmth of the water returning to it rather than the water leaving it, which is a specific setting typically used for underfloor heating systems.

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

Heating control: off=Flow temperature, on=Return temperature (adjustment for underfloor heating)

Engineer required

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

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