Dimplex Heat Exchanger Kettling / Localised Boiling

Boiler makes loud banging or knocking noises (kettling) during operation

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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 Dimplex primary heat exchanger, Sludge in system restricting flow, Pump running at too low speed, Incorrect system balancing causing low flow through boiler

How to Fix / Troubleshooting

Safety first: Noisy boilers can indicate overheating. Do not ignore persistent banging sounds.

User actions:

  • Check pressure: Ensure system pressure is correct.
  • Open all valves: Make sure all radiator valves and isolation valves are fully open to maximise flow.
  • Bleed radiators: Remove trapped air which can worsen kettling.

Professional treatment:

  • Powerflush the heating system and clean any Dimplex system filters.
  • Descale or replace the Dimplex primary heat exchanger if heavily scaled.
  • Adjust Dimplex pump speed and balance radiators to ensure adequate flow.
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Repair Difficulty

Hard 4/5

Required Part

Dimplex primary heat exchanger
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