BoilerFaultCodesTechnical description
DHW mode – fan overrun
What causes this fault?
This occurs when the boiler’s internal heat exchanger needs to shed excess heat after you have finished using a hot water tap. The boiler activates the fan to pull cool air through the unit to prevent internal components from getting too hot. It is a standard safety and maintenance process rather than a mechanical failure.
This may be more noticeable in summer when the incoming cold water mains temperature is higher, meaning the boiler has less naturally cold water to help it cool down quickly.
DIY fix possible
No action is required as this is a normal operating status and not a fault.Wait a few minutes for the fan to stop automatically.If the fan never stops, contact a Gas Safe engineer to check the control board.
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