Remeha Kettling / rapid boiling in heat exchanger

Furnace makes loud banging or knocking noises when starting or stopping

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 buildup in heat exchanger, Low system flow rate, Incorrect pump speed, Air in heat exchanger

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

Check system pressure and bleed: Ensure pressure is correct and bleed air from radiators and any automatic air vents.
Increase pump speed: If the pump has adjustable speed, set it to a higher setting to improve flow.
Descale heat exchanger: A technician can chemically descale the primary heat exchanger using approved products.
System treatment: After cleaning, add corrosion inhibitor to the system to reduce future scale and sludge formation.

Hard 4/5

Primary Heat Exchanger

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