Boiler shows A24, burner stops, error often appears at high output

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

Scaled or blocked primary heat exchanger, sludge in system, failed pump, closed valves

Safety: Allow boiler and system to cool before working on water components.

Check system flow: Ensure all radiator valves are open and that any zone valves are operating correctly.
Clean filters: Clean any system filter or strainer on the return to the boiler.
Technician tasks: A heating engineer may need to chemically flush the system, clean or replace the primary heat exchanger, and verify pump performance.

Hard 4/5

Primary Heat Exchanger

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