Boiler shows A8, hot water may not reach set temperature or may fluctuate.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Stuck or scaled DHW flow turbine, Blocked inlet filter, Faulty flow sensor, Wiring fault to sensor

Safety first: Turn off power and close the cold water isolation valve under the boiler before removing any water components (engineer only).

User checks: Ensure all hot water outlets are fully opened when testing and that cold mains pressure is present at other taps.
Clean inlet filters (if accessible): Some models have a user-cleanable inlet filter on the cold feed; follow the manual if provided.
Engineer tasks: An engineer should inspect and clean/replace the DHW flow turbine assembly, check the inlet filter, and test the sensor signal at the PCB.

Hard 4/5

DHW Flow Sensor / Turbine

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