Temperature limiter (FD1) tripped — Electrical addition power cut due to high temperature

What does FD1 tripped mean?

The temperature limiter, labelled FD1, has automatically cut the power supply to the electrical addition. This happens as a safety measure if the internal temperature rises between 90 and 100°C. It can be manually reset.

• Overheating of the electrical addition
• Insufficient water in the boiler or system
• Pump malfunction or blockage
• Sensor error indicating false high temperature

Click steps to track your progress.

1. 1

   Power off the heat pump at the main circuit breaker.

2. 2

   Allow the unit to cool down completely for at least 30 minutes.

3. 3

   Carefully open the front cover to access FD1, which is located behind the front cover.

4. 4

   Reset the temperature limiter by pressing the button (FD1-SF2) using a small screwdriver.

5. 5

   Power on the heat pump and monitor its operation. If it trips again, contact NIBE service.