It typically functions as an on/off controller. When the temperature drops below the setpoint, it triggers a relay to turn on your heating device (like a heat tape, terrarium heater, or heating element). Once the target temperature is reached, it cuts the power.

The pilot light will turn when the controller is calling for heat, and OFF when the set temperature is reached. This cycling is normal.

To access advanced settings: until the screen shows a parameter code (typically F1 ).