16
RT-SVX36G-EN
General Information
Ventilation Control Module
VCM
The Ventilation Control Module (VCM) is located in the filter section of the unit and is linked to the
unit's UCM network. Using a “velocity pressure” sensing ring located in the fresh air section,
allows the VCM to monitor and control the quantity of fresh air entering the unit to a minimum
airflow setpoint.
An optional temperature sensor can be connected to the VCM which enables it to control a field
installed fresh air preheater.
An optional CO
2
sensor can be connected to the VCM to control CO
2
reset. The reset function adjust
the minimum CFM upward as the CO
2
concentrations increase. The maximum effective (reset)
setpoint value for fresh air entering the unit is limited to the systems operating CFM. The following
table lists the Minimum Outside Air CFM vs. Input Voltage.
The velocity pressure transducer/solenoid assembly is illustrated below. Refer to the “Traq Sensor
Sequence of Operation” section for VCM operation.
Figure 1.
Humidity vs. Voltage
Table 3.
Minimum Outside Air Setpoint w/VCM Module and Traq Sensing
Unit (AC/EC)
Input Volts
CFM
20 & 25, 24 & 29 Ton
0.5-4.5 VDC
0-14000
30/36 Ton
0.5-4.5 VDC
0-17000
40/48 Ton
0.5-4.5 VDC
0-22000
50/59, 55 Ton
0.5-4.5 VDC
0-28000
60-75, 73-89 Ton
0.5-4.5 VDC
0-33000
90-130 Ton
0.5-4.5 VDC
0-46000
