Low
d.51 on Vaillant Home System

Your boiler is automatically adjusting its fan speed to compensate for issues with the air supply or flue gases.

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

Correction of the maximum fan speed: -2500 to 0 rpm. Fan speed=Display value x 10

From this model's manual
Verified against the Vaillant Home System installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

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

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F.32View →d.50View →

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