Attack
Kettling / Hydraulic Shock
Boiler makes loud banging or knocking noises when starting or stopping.
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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 buildup inside Attack primary heat exchanger, Incorrect pump speed or flow rate, Air in primary circuit, Rapid temperature rise due to blocked flow
How to Fix / Troubleshooting
Safety: No immediate danger in most cases, but persistent banging can damage components. Turn off the boiler if noises are severe.
Steps:
- Bleed system: Remove air from radiators and the boiler’s automatic air vent to improve circulation.
- Check pump setting: Ensure the Attack pump is set to an appropriate speed for the system size.
- Clean filters: Clean any system filter to restore proper flow.
- Descale heat exchanger: Have a professional chemically descale the primary heat exchanger if limescale is suspected, especially in hard water areas.
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Repair Difficulty
Medium
3/5
Required Part
Primary Heat Exchanger
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