A11
De Dietrich Flow Sensor / Turbine Fault (DHW)

Boiler displays A11, intermittent operation, sometimes linked to DHW demand

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Safety Warning

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.

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Possible Causes

Stuck or scaled domestic hot water flow turbine, faulty DHW flow sensor, wiring fault to sensor

How to Fix / Troubleshooting

Safety: Isolate power and close cold water inlet before opening any water components. Expect water spillage.

  • Check DHW demand: Open a hot tap fully. The boiler should detect flow and start. If not, suspect the DHW flow sensor/turbine.
  • Clean or replace turbine: On combi models, remove the DHW flow sensor assembly (refer to De Dietrich manual). Check for limescale or debris. Clean gently or replace the turbine cartridge.
  • Inspect wiring: Ensure the sensor connector is firmly seated on the PCB.
  • Technician tasks: A professional can measure sensor signals and replace the sensor or PCB if no signal is detected.
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Repair Difficulty

Medium 3/5

Required Part

DHW Flow Sensor / Turbine
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