Low
d.17 on Vaillant Home System

Your boiler has been adjusted to measure the temperature of the water returning from your radiators rather than leaving the boiler, which is a standard setting often 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)

DIY fix possible

Navigate to the 'd.17' setting in the installer level menuChange the value from 1 (Return) to 0 (Flow) if you do not have underfloor heatingPress the 'Menu' or 'M' button to save the setting and exit

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Related fault codes

d.00View →d.01View →d.02View →

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