Boiler makes loud banging or knocking noises (kettling) during operation, especially on central heating demand.
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: Turn down the boiler flow temperature to reduce stress until the issue is resolved. Do not ignore persistent banging noises.
User checks:
- Ensure all radiator valves are open to allow adequate flow.
- Check system pressure and top up if low.
- Reduce the CH flow temperature setpoint on the boiler control panel.
Technician checks:
- Assess the level of limescale and sludge; perform a chemical flush of the system if necessary.
- Clean or replace the primary heat exchanger if heavily scaled.
- Check the circulation pump speed setting and increase if appropriate.
- Install or clean a magnetic filter to protect the boiler from future sludge.
After treatment, re-balance the heating system and verify quiet operation.
Repair Difficulty
Required Part
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