F.20 - Safety switch-off: Temperature limiter

What does F.20 mean?

The boiler has performed a safety shutdown because a temperature limiter was activated. This indicates that a critical temperature threshold was exceeded, often due to electrical or sensor issues.

• Incorrect earth connection between the cable harness and the product.
• Flow or return NTC sensor is defective or has a loose connection.
• Black discharge via the ignition cable, ignition plug, or ignition electrode.

Click steps to track your progress.

1. 1

   Press the reset button on the boiler display up to three times to try and clear the fault.

2. 2

   Contact customer service immediately. This is a safety shutdown due to high temperature, potentially caused by electrical issues or faulty temperature sensors.

3. 3

   A qualified technician will need to check the earthing, NTC sensors, and the ignition system for proper function.