LX Series Unit Ventilator Controller User's Guide
22
Sensors and Switches
The following sensors and switches can be connected to the Unit Ventilator
Controller. See Table 3 for the sensor and switches preferred SNVT types.
Auxiliary Alarm Input
This input is used to relay an alarm from an external device onto the building
network.
Bypass Contact Input
If the UVC is in unoccupied or standby mode, you can use switch closure on the
bypass contact input to cause the controller to enter occupied mode for the time
period time set as the bypass time.
CO
2
Level Input
Use this input to monitor the CO
2
concentration. The CO
2
concentration can be
used for Demand Control Ventilation (DCV) and to set the minimum damper
position during heating or cooling operations.
If you do not want to use the CO
2
concentration input, the minimum damper
position can be set in a fixed position, or as a fixed percentage of fresh air intake.
You can find the fresh air intake percentage by a calculation of the return air,
outdoor air, and mixed air temperatures.
Discharge Temperature Input
Use the discharge temperature input to maintain the discharge air temperature
between the minimum and maximum discharge air temperature.
The discharge temperature setpoint is determined by a linear equation between the
minimum and maximum discharge air temperature and the terminal load. When
there is a high heating demand, the discharge temperature setpoint moves to its
maximum temperature. Conversely, for a high cooling demand, the discharge
temperature setpoint moves to its minimum temperature. The discharge
temperature setpoint can be viewed in the nvoDischargSetPt.
Economizer Enable Input
Select this input to allow switch closure to enable the economizer. The economizer
position can then be controlled in several different ways. See the
section.
Emergency Contact Input
Use switch closure on this input to cause the UVC to begin emergency operation.
See the
section.
Fan Speed Selector Input
Fan speed selector gives the Unit Ventilator Controller the ability to select up to
three different fan speeds.
