ACV Heat Exchanger Kettling / Localized Boiling

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 buildup in primary heat exchanger, Sludge in system water, Poor circulation, Incorrect pump speed

Safety first: Persistent kettling can damage the boiler. Reduce demand and seek service.

Check system pressure and bleed: Ensure correct pressure and remove air from radiators and vents to improve circulation.
Open all valves: Make sure all isolation valves around the ACV boiler and key radiators are fully open.
Magnetic filter: If fitted, clean the system filter to improve flow.
Professional descaling: A technician should chemically clean or powerflush the system, descale the ACV primary heat exchanger, and adjust pump speed.

Hard 4/5

Primary Heat Exchanger

Check Price on Amazon

We may earn a commission from links on this page.