Worcester Bosch Mechanical Noise from Fan or Pump

Boiler is very noisy with whirring, grinding, or rattling sounds 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

Worn fan bearings, Worn pump bearings, Air in pump, Loose mounting brackets or panels

How to Fix / Troubleshooting

Safety first: Persistent mechanical noise can indicate imminent component failure.

  • Identify noise source: Carefully listen to determine if the noise is from the top (fan) or lower front (pump) of the boiler.
  • Bleed system: Remove air from radiators and pump (if bleed screw fitted) to reduce cavitation noise.
  • Tighten casing screws: With power off, gently tighten any loose outer case screws that may cause rattling.
  • Engineer tasks: An engineer should inspect and replace the noisy fan or pump and check for correct installation and vibration damping.
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Repair Difficulty

Hard 4/5

Required Part

Fan Assembly or Circulation Pump
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