Viconics VBZS Application Guide - Manual (Page 28)

28
Economizer Mode, CO
2
Level Control and Fresh Air Measurement Station
If the fresh air damper is to be used for both free cooling and CO
2
level control with a fresh air
measurement station, only the Min FA, Max FA, Min CO
2
and Max CO
2
parameters as well as the free
cooling sequence will be active.
- The FA Range parameter should be set to something other than 0 CFM.
- Use an air flow transmitter to read fresh air level with AI2 input (0-5 VDC input)
- Min FA, Max FA, Min CO
2
and Max CO
2
parameters should be set according to the required
setting.
Min FA
Setpoint
Max FA
Setpoint
Min CO
2
Max CO
2
Current
Fresh Air
Setpoint
Current
CO
2
Level
The higher value between free cooling output and interpolation output based on the above graphic will be
the signal sent to the fresh air damper. If the occupancy is unoccupied, then the CO
2
control output will be
0%.