8
Intergas Flow Sensor / Turbine Fault (DHW Flow Detection)

Code 8 displayed, boiler cycles rapidly or does not modulate correctly

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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 DHW flow turbine, Blocked DHW inlet filter, Faulty flow sensor reed switch, Wiring fault between flow sensor and PCB

How to Fix / Troubleshooting

Safety first: Isolate electrical power and close the cold water inlet to the boiler. Relieve pressure by opening a hot tap before removing any DHW components.

Steps:

  • Clean inlet filter: Remove and clean the cold water inlet filter/strainer on the Intergas boiler. Debris can prevent the flow turbine from spinning.
  • Inspect flow sensor: Locate the DHW flow sensor/turbine assembly. Remove it carefully and check for limescale or debris. Clean with a soft brush.
  • Check turbine movement: Ensure the turbine spins freely when blown or moved by water.
  • Test reed switch (technician): With a multimeter, verify that the reed switch opens and closes as the turbine magnet passes. Replace the flow sensor assembly if faulty.
  • Check wiring: Inspect the harness from the flow sensor to the PCB for damage or loose connections.

After reassembly, open the cold inlet, purge air, and test hot water demand. If code 8 persists, further PCB diagnostics by a professional are required.

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Repair Difficulty

Hard 4/5

Required Part

DHW flow sensor / turbine assembly
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