Baxi Heat Exchanger Kettling Due to Limescale

Unusual banging or knocking noises from the Baxi water heater during operation (kettling).

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

Heavy limescale buildup in primary heat exchanger, Poor water quality without softening, Restricted circulation through heat exchanger, Air trapped in primary circuit

How to Fix / Troubleshooting

Safety: Noises may indicate local overheating. Monitor for overheat trips.

Steps:

Bleed air (if applicable): On models with bleed points, carefully vent air from the primary circuit when cool.
Check system pressure: Ensure primary pressure is within the recommended range.
Water treatment: In hard water areas, consider installing a scale reducer or softener on the cold feed.
Professional descale: A technician should chemically descale or replace the primary heat exchanger if kettling is severe.

Repair Difficulty

Hard 4/5

Required Part

Primary Heat Exchanger

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