Remeha Boiler kettling / localised boiling in heat exchanger

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

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

Limescale build-up in primary heat exchanger, Sludge in system water, Poor circulation due to failing pump, Incorrect system design causing low flow

Safety first: If noises are violent or the boiler casing becomes excessively hot, switch off the boiler immediately and allow it to cool.

Check system pressure and bleed: Ensure pressure is correct and bleed radiators to remove air, which can worsen kettling.
Listen to pump: Confirm the pump is running smoothly and not noisy or stuck.
Engineer tasks: Power-flush or chemically clean the system, descale or replace the primary heat exchanger, check pump performance, and verify correct flow rates through the boiler.

Hard 4/5

Primary Heat Exchanger

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