Beretta
Kettling / Localised Boiling in Heat Exchanger
Boiler makes loud banging or knocking noises (kettling) during operation, especially on heating.
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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 primary heat exchanger, Sludge in system water, Poor circulation due to partially blocked pipes or pump, Incorrect system pressure
How to Fix / Troubleshooting
Safety: Turn off the boiler if banging is severe to avoid damage.
- Check system pressure: Ensure pressure is around 1.0–1.5 bar when cold. Top up if needed.
- Bleed radiators: Remove air from the system to improve circulation.
- System cleaning (technician): Power-flush the heating system and add inhibitor to remove sludge and scale.
- Descale primary heat exchanger: Remove and chemically descale or replace the Beretta primary heat exchanger if heavily scaled.
- Check pump performance: Ensure the circulation pump is correctly sized and running at appropriate speed.
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Repair Difficulty
Hard
4/5
Required Part
Primary Heat Exchanger
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