HF31 — Zone Temperature Sensor Out of Operating Range

What does HF31 mean?

An HF31 error indicates that the zone temperature sensor is reading a temperature outside its normal operating range of 30 to 180 F. This could be due to a sensor malfunction, improper installation, or wiring issues.

• Physically damaged zone temperature sensor or shorting against the slave thermostat circuit board.
• Improper wiring connections for a remote room temperature sensor, or the slave thermostat's internal sensor not removed.
• Remote room sensor wiring running too close to AC, control, or communication bus wiring.
• Incorrect calibration of the zone temperature sensor.

Click steps to track your progress.

1. 1

   Check if the zone temperature sensor on the slave thermostat circuit board is physically intact and not shorted.

2. 2

   If using a remote room temperature sensor, ensure proper wiring connections and that the slave thermostat's internal sensor has been removed.

3. 3

   Verify that remote room sensor wiring maintains a minimum separation of 12 inches from other AC, control, or communication bus wiring.

4. 4

   Calibrate the zone temperature sensor manually at the slave thermostat using a thermometer. Turn the rotary switch to position 6 and adjust the display to match the thermometer reading.

5. 5

   If manual calibration fails, use the Device Calibration software with an accurate thermometer to adjust and update the sensor reading.