Boiler makes loud banging or knocking noises (kettling) during operation, especially when heating starts or stops.
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: No immediate gas hazard, but overheating can damage the boiler. If noises are severe, switch off the boiler and allow it to cool.
User-level checks:
- Ensure all radiator valves are open to allow good circulation.
- Check system pressure and top up if low.
Technical checks (qualified personnel):
- Assess the level of sludge in the system; consider powerflushing or chemical cleaning.
- Descale the primary heat exchanger using an appropriate descaling pump and chemicals compatible with Chaffoteaux boilers.
- Verify pump speed and adjust to ensure adequate flow through the boiler.
- Add inhibitor to the system water after cleaning to prevent future scale and corrosion.
Persistent kettling after cleaning may indicate the need to replace the primary heat exchanger.
Repair Difficulty
Required Part
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