A22
De Dietrich 3-Way Diverter Valve Position Fault

Boiler shows A22, DHW priority not working correctly, heating locked out

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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 diverter valve, faulty diverter motor/actuator, scale or debris in valve body, wiring fault to actuator

How to Fix / Troubleshooting

Safety: Isolate power and water supply before removing the diverter valve. Expect water leakage.

  • Check DHW vs heating: Run a hot tap and see if radiators heat instead of DHW, or vice versa. This indicates a diverter issue.
  • Manual movement: Some diverter valves have a manual lever. Gently move it to see if it is stuck.
  • Clean or replace: Remove the actuator head and check for free movement of the valve spindle. If stiff, the valve body may need replacement. If the motor does not move when powered, replace the actuator.
  • Technician tasks: A professional should test actuator voltage and replace the diverter assembly if necessary.
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Repair Difficulty

Hard 4/5

Required Part

3-Way Diverter Valve
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