Low
S.27 on Vaillant Home System

Your boiler is briefly keeping the pump running after heating your hot water to safely dissipate excess heat from the internal system.

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

From this model's manual
Verified against the Vaillant Home System installation & service manual, page 33.
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 message.Ensure your radiator valves or bypass valves are open to allow heat to move away from the boiler.Check that your digital programmer is not stuck in a constant 'on' demand for hot water.

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