BoilerFaultCodesTechnical description
DHW mode: Fan overrun. The fan overrun for domestic hot water mode is activated.
What causes this fault?
This occurs when the boiler detects a buildup of residual heat in the internal heat exchanger after you have finished using hot water. The system pulses the fan to pull fresh air through the unit and flush out any remaining combustion gases or excess heat. It is a safety and cooling feature rather than a mechanical failure.
This status may appear more frequently during the summer when the incoming cold water feed is warmer, as the boiler does not need to work as hard to maintain its internal temperature.
DIY fix possible
No action is required as this is a normal operational status message, not a breakdown code.Wait a few minutes for the fan to stop automatically once the cooling process is complete.If the code never disappears or the fan runs constantly for hours, try resetting the boiler once.