sensor fault BT71 — External heating medium return sensor not connected or defective

What does 28 mean?

The BT71 sensor, which monitors the external heating medium return, is not connected or defective. No action is taken by the Heat Pump unless combined with alarm 25, in which case heat is blocked.

• BT71 sensor is disconnected or has a loose connection.
• The sensor unit is faulty or damaged.
• Wiring problems to the sensor.

Click steps to track your progress.

1. 1

   Power cycle the Heat Pump by turning off the main breaker for 30 seconds.

2. 2

   Check the physical connections to the BT71 sensor to ensure they are secure.

3. 3

   If alarm 25 (BT25 fault) is also active, inspect its connections as well.

4. 4

   Restore power and observe if the alarm clears.

5. 5

   If the problem continues, a service technician should perform a diagnostic check.