The TR3840 smart sensor is a slim attractive wall mounted temperature sensor with excellent temperature sensing due to a tiny fan that draws air in from the bottom of the housing over the sensor and discharges through the top. The fan is located at the top of the housing and draws air through an inlet plenum. The sensor is located at the bottom of the housing in the inlet plenum. The fan also draws air from the electronics section to remove heat. To average the temperature readings in a large zone up to 4 Smart sensors can be connected to the TC5044 universal controller. 

It has a 2 x 16 character LCD display and four pushbuttons. These are located behind a door with a viewing aperture for the display. The pushbuttons are Raise and Lower for setpoint adjustment, Select pushbutton to enable functions and a System On/Off pushbutton to turn the Air Conditioning System on and off when function Menu 25 or 26 is enabled.