Select a fault code

Failed to ignite. Gas supply issue, faulty electrode, or gas valve fault.

Primary circuit overheated and the high limit thermostat has tripped. Common causes: pump failure, very low system pressure, or blocked heat exchanger.

Air pressure switch not making — fan not running, flue blocked, or pressure switch fault.

Plate heat exchanger overheating. Blocked plate heat exchanger (scale) or flow sensor fault.

NTC thermistor on the flow pipe has failed or is disconnected.

Return NTC thermistor fault — open circuit or short circuit.

Flame sensor detecting a signal when burner is off — ionisation rod or gas valve fault.

System pressure below minimum operating level (typically 0.5 bar).