Main
Kettling Due to Scale or Sludge in Primary Heat Exchanger
Boiler makes loud banging or kettling noises during operation
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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
Limescale build-up in Main primary heat exchanger, Sludged heating system, Incorrect inhibitor levels, Poor circulation
How to Fix / Troubleshooting
Safety: Noisy boilers may be overheating; do not ignore persistent banging. Allow the system to cool before touching pipework.
- Check system pressure and bleed: Ensure pressure is around 1.0–1.5 bar and bleed radiators to remove air that can worsen noise.
- Verify all valves open: Confirm that all radiator and isolation valves are open to allow full circulation.
- Engineer actions:
- Assess the Main primary heat exchanger for scale and consider chemical descaling.
- Powerflush the heating system and add corrosion inhibitor.
- Check pump performance and replace the Main pump if circulation is poor.
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Repair Difficulty
Medium
3/5
Required Part
Primary Heat Exchanger
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