De Dietrich Kettling / Boiling in Heat Exchanger

Water heater makes loud banging or knocking noises 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

Heavy limescale buildup in De Dietrich primary heat exchanger, Restricted water flow, Incorrect pump speed setting, Air trapped in system

Safety first: Noises may indicate localized boiling; monitor for overheating and leaks.

Step-by-step checks:

Bleed air: Bleed radiators and any automatic air vents to remove trapped air.
Check pump speed: If the pump has adjustable speeds, set it to a higher speed to improve circulation.
Descale: In hard water areas, schedule professional descaling of the heat exchanger.

When to call a professional: Persistent kettling usually requires chemical cleaning or replacement of the heat exchanger.

Hard 4/5

Primary Heat Exchanger

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