Boiler shows F83, especially after filling or during start-up

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

Air in primary circuit, partially blocked heat exchanger, low flow rate, incorrect sensor contact

Safety: Bleed air carefully to avoid hot water burns.

Bleed boiler: Use the automatic air vent and any manual vents on the boiler to release trapped air.
Bleed radiators: Starting from the lowest floor, bleed all radiators and towel rails.
Check pump and valves: Ensure pump is running and all valves are open.
Sensor contact: Confirm the flow NTC is firmly attached to the pipe with good thermal contact.
Persistent F83: May indicate partial blockage; a technician should inspect and flush the primary circuit.

Medium 3/5

Flow Temperature Sensor (NTC)

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