B3
Nibe
Hot water circulation pump fault
B3 alarm, no hot water circulation through cylinder coil, poor hot water performance
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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
Seized DHW circulation pump, air‑locked cylinder coil, blocked check valve, failed pump module
How to Fix / Troubleshooting
Safety: Turn off power and allow the cylinder to cool before working on the pump.
- Verify demand: Ensure the Nibe controller is actually calling for hot water (check DHW status in the menu).
- Check pump vibration: With power on and DHW demand active, feel the DHW pump. If silent, check its isolator and fuses.
- Bleed the circuit: Use bleed valves on the cylinder coil circuit to remove air. Airlocks are common after maintenance.
- Free the rotor: If the pump is accessible, remove the motor head and gently rotate the impeller to free it.
If the B3 alarm remains, replace the DHW circulation pump with a Nibe‑approved model.
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Repair Difficulty
Medium
3/5
Required Part
DHW Circulation Pump
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