F15
Protherm
Flow Sensor Signal Range / Plausibility Error
F15 displayed, appliance may not detect water flow correctly or modulate temperature
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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
Partially blocked flow sensor, Incorrect sensor type fitted, Electrical noise on sensor line, Control board input fault
How to Fix / Troubleshooting
Safety first: Turn off power and close water valves before removing any hydraulic parts.
- Clean flow sensor: Remove and clean the DHW flow sensor/turbine, ensuring it spins freely and is free of scale.
- Verify correct part: Confirm that the installed flow sensor matches the Protherm part number for this model.
- Check cable routing: Ensure the sensor cable is not routed alongside mains or ignition cables that can induce noise.
- Replace sensor or PCB: If the sensor is clean and correct but F15 persists, replace the sensor. If still unresolved, the PCB input may be faulty and require replacement.
Warning: Always depressurize the system before removing the flow sensor to avoid water damage.
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Repair Difficulty
Medium
3/5
Required Part
DHW Flow Sensor / Turbine Assembly
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