Viconics VBZS Application Guide - Manual (Page 25)

25
Economizer Control Mode Only
If the fresh air damper is to be used only for free cooling purposes (economizer mode, without fresh air
measurement station or CO
2
control), only the Min Pos parameter and the free cooling sequence will be
active.
- The FA Range parameter should be set to 0 CFM. (Default Value = 0 CFM)
- Set the Chngstpt parameter to desired value which free cooling is enabled. (Default Value =
55°F)
If the outside air temperature is greater than the changeover setpoint, then normal mechanical cooling will
be used. If the outside air temperature is less than or equal to the changeover setpoint, then free cooling
will be enabled and mechanical cooling stages will be locked out.