Boiler intermittently locks out with E9 219, often during high demand.

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

Insufficient circulation, Closed or partially closed valves, Undersized or blocked pipework, Pump running at too low a speed

Safety first: Allow the system to cool before adjusting valves.

Open valves fully: Ensure all isolation valves near the boiler and on the heating circuit are fully open.
Check TRVs: Make sure not all TRVs are closed; at least one radiator without a TRV should be fully open to allow bypass flow.
Engineer tasks: A professional should check pump speed settings, balance the system, and inspect for blockages or undersized sections of pipework causing high temperature differential.

Medium 3/5

Circulation Pump Assembly

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