Potterton
Hydraulic Shock / Kettling
Boiler makes loud banging or knocking noises when starting or stopping (water hammer / kettling)
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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
Scale in primary heat exchanger, Poorly supported pipework, Rapid valve closure, Incorrect pump speed
How to Fix / Troubleshooting
Safety first: Turn off the boiler if noises are severe to avoid damage.
User checks:
- Ensure all radiator valves are fully open and not being rapidly turned off and on.
- Bleed radiators to remove trapped air.
Engineer checks:
- Check pump speed and adjust to a lower setting if flow is excessive.
- Inspect pipework near the boiler for loose clips and secure as needed.
- Assess the primary heat exchanger for scale and perform a chemical descaling or replace if necessary.
- Fit shock arrestors or adjust valve closing speeds if water hammer is present.
Reducing scale and stabilising flow usually resolves banging noises.
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Repair Difficulty
Medium
3/5
Required Part
Primary Heat Exchanger
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