Low
D.18 on Vaillant Atmomax

Your boiler is currently set to run the internal pump continuously rather than only when needed for heating or hot water.

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

Pump mode return

Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Navigate to the installer level settings (D.18) using the 'i' and '+' buttons.Check if the value is set to '1' (Continuous) or '0' (Automatic/Intermittent).Change the value back to '0' if you prefer the pump to stop when there is no demand for heat.

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