If there is cooling demand while outside air is suitable for economizing, the Economizer Controller tries to increase fan speed to maximize the use of outside air first. If the cooling demand is not reached within a set time, mechanical cooling will be enabled.

Typical Field Application

Prerequisites:

  • Outside air is suitable for economizing and free cooling is ON.
  • Fan connected to the controller supports multiple speeds. Cooling delay function doesn't work if only a one-speed fan is connected to the controller.
  1. If it is a 2-speed fan and there are two cooling demand inputs/outputs, Y1-Input is called, the controller sets fan speed to Speed Low. Damper is fully open (100%).
  • If Y2-Input is called too, the controller increases fan speed to Speed High and starts fan delay (2FAN DLY) time. After the delay time runs out, the controller starts Y1-Output.
  • If the cooling demand is not reached after Y1-Output is ON within '3STG3 DLY' time and OAT is higher than MAT setpoint (3MAT SET), the controller starts Y2-Output.
  • If it is a 3-speed fan, Y1-Input is called, the controller sets fan speed to Speed Low. Damper is fully open (100%).
    • If Y2-Input is called too, the controller increases fan speed to Speed Medium and starts '2FAN DLY' time. After the delay time runs out, the controller starts Y1-Output.
    • If Y3-Input is called too, the controller increases fan speed to Speed High and starts '2FAN DLY' time. After the delay time runs out, the controller starts Y2-Output.
    • If the cooling demand is not reached after Y2-Output is ON within '3STG3 DLY' time and OAT is higher than MAT setpoint, the controller starts Y3-Output.
  • If a variable-speed fan is configured, cooling delay functions the same with 3-speed fan.
    • NOTICE

    See more information about '2FAN DLY' and '3STG3 DLY' in Setup and Configuration. The default time is 5 and 15 minutes respectively.