This is the room sensing probe that is attached to the back or side of all Harman pellet stoves and inserts. Its purpose is to read the return air temperature when the controls are set to “Room Temperature” mode. It is located next to the power input plug on all stoves and inserts.
If your Harman pellet stove or insert is connected to the Harman Wireless Room Sensor, this wired room sensor is bypassed. If the connection to your wireless sensor is lost, the stove will revert to using this sensor if it is connected. If your stove does not detect the wireless sensor or this probe, the unit cannot be used in “Auto” mode and will error out.