F23 error, unit may start then quickly shut down, sometimes with loud boiling noises

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

Restricted flow through heat exchanger, Air in primary circuit, Pump not circulating properly, Scaled heat exchanger

Safety first: Isolate power and allow the unit to cool.

Steps:

Bleed system: Remove air from the primary circuit using bleed valves or automatic vents.
Check pump: Confirm that the circulation pump is running and not seized.
Clean filters: Clean any strainers in the primary circuit.
Descale: If differential remains high, arrange for descaling of the primary heat exchanger.

Warning: Boiling noises indicate localized overheating. Continued operation can cause serious damage.

Hard 4/5

Circulation Pump

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