Low
S.27 on Vaillant Atmomax

Your boiler is temporarily running its internal pump to cool down the internal components after you have finished using 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

DHW mode – pump overrun

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

No action is required as this is a normal operational status rather than a fault.Wait a few minutes for the pump symbol to disappear.Ensure your radiator valves are open to allow heat to dissipate if the boiler is frequently running hot.

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