Economizer control (optional) - Verasys - LIT-12013067 - LC-IOM3711-0 - LC-VAC1000-0 - LC-VAC3000-0 - Field Device - VAC1000 - VAC3000

Verasys Constant Volume Controller Application Note

Brand
Verasys
Product name
VAC1000
VAC3000
Document type
Application Note
Document number
LIT-12013067
Revision date
2021-10-13
Language
English

You can configure an economizer with the following settings.

From the Details menu, click System Configuration and select to set the economizer damper type. Use the following list to understand the available settings:

  • None - There is no economizer connected, or another device controls an economizer.
  • Min OA - The damper opens to a minimum position when the unit is in the occupied mode. Low limit logic does not affect this position and it remains constant.
  • Economizer - The controller modulates the damper section when the outdoor air temperature is cooler than the economizer setpoint. The economizer acts as the initial stage of cooling and works in sequence with the cooling output.

In the Economizer section of the Commissioning menu, the low limit control is active when the Economizer Damper Type is set to Economizer and the low limit temperature is below the Low Limit Temp Setpoint. The Low Limit Temp Setpoint is either Mixed Air or Supply Air as dictated by Min OA Sensor.

Note: If the cooling coil control or heating coil control is proportional, this feature is not optional and requires a mixed-air sensor, not a supply air sensor.

To set the option for demand control ventilation, set the CO2 Sensor Installed parameter on the Sensors section of the Details menu. Change the setting from Not Installed to one of the three following settings:

  • SAB sensor (ZN-Q)
  • Hardwired sensor (RA-Q)
  • Both

When you choose one of these settings, the sensors reset the damper minimum position as the CO2 sensor rises above the CO2 setpoint. If both sensors are installed, the hardwired sensor (RA-Q) takes priority.

Note: From the Commissioning menu, navigate to the Economizer section to configure the CO2 reset settings. The true minimum position output of the economizer spans between user-adjustable Minimum OA Percent and Min Pos High Setpoint based on the CO2 Reset A, CO2 Reset B, and measured CO2.