Economizer

Configuring Unit Ventilator Economizer

Use the Unit Ventilator Economizer page to configure Economizer settings.

Purpose

Define Economizer functions.

Mode

Off-line or On-line

Procedure

Click the Economizer button on the left pane to open the Economizer Configuration Page.
Enter information into available fields.
Click Commit to save the settings or Reset to revert to the last saved settings.
Click Next to display the H/C Stage Parameters Configuration page or Back to display the Equipment Control Configuration page.

Fields

Name	Definition
IAQ Sensor Setpoint	This is the Indoor Air Quality setpoint. This setting, in ppm, is compared to the current actual indoor CO2 sensor reading to determine the indoor air quality.
OAQ Sensor SetPoint	This is the Outdoor Air Quality setpoint. This setting, in ppm, is compared to the current actual outdoor CO or CO2 sensor reading to determine the outdoor air quality. If OAQ is poor, the economizer damper is closed to 0%.
Enable Type	Source for economizer enable decisions. Choose one of the following methods to determine when to use outdoor air for cooling: Digital OutDoorTemp OdEnth Type A OdEnth Type B OdEnth Type C OdEnth Type D DiffTemp SingleEnth DiffEnth EconNul
OA Damper Min Pos	Minimum position of the Outdoor Damper (0 to 100%). Under normal Occupied-mode operation, the dampers are not closed below this setting. If Unoccupied, or if a Discharge Low Temperature condition exists, the dampers are closed below this setting.
IAQ Position	Minimum Position of Damper used when poor Indoor Air Quality conditions exist (IAQ sensor > IAQ Setpoint, or if Digital IAQ Switch is on). Value range from 0 to 100%. NOTE: A discharge low temperature condition overrides this setting and closes the dampers to prevent equipment damage due to freezing.
Use Heat for IAQ	Select one of the following options: Yes - Enables heat to be used when the damper is opened for IAQ purposes. No - Keeps heat disabled if controller is in Cool mode.
Oa Temp High Limit	This field is enabled only when Enable Type is set to Single Enth(alpy). It provides an outdoor air temperature high limit setting, above which, the economizer is disabled, regardless of the current enthalpy value.
Mixed Temp Setpoint (ASHRAE Cycle 3 Only)	This field is enabled only when ASHRAE Cycle III is selected in the Equipment Control Tab.
Ashrae Cycle	When a unit ventilator is in the occupied mode it typically follows one of three operating cycles defined by the American Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc. (ASHRAE): Cycle I: Fixed 100% Outdoor Air Cycle II: Variable Percentage of Outdoor Air with Minimum Position setting Cycle III: Variable Outdoor Air Maintaining Constant Mixed Air Temperature
Enable Setpoint/ OaEconEnTemp/ DiffEconEnTemp/ OaEnthEn	This setpoint is enabled if Enable Type is Outside Air Temp, Diff. Temp, or Single Enth For OdTemp, this field sets the threshold, above which, the economizer is disabled. For Diff Temp, this field sets the difference between the Outdoor and Return air temperatures, above which, the economizer is disabled. For Single Enth, this field sets the enthalpy value, above which, the economizer is disabled.