Programming instructions

Appendix A: Worksheets
83
Variable stage settings worksheet
Variable cooling stages
Programming variable cooling stages means programming the following settings. For more
information, read Programming variable stages on page 46.
Information
Name Address
Building Type
Setting VAR 1 VAR 2 VAR 3 VAR 4 Description
Differential

 The fan is at full speed when the temperature is at
or above this value.
Set point

 Fan speed increases when the temperature is
between this value and the differential temperature.
 The fan is at idle speed when the temperature is
between this value and the idle range.
Idle range

 The fan is at idle speed when the temperature is
between this value and the set point.
 The fan is off when the temperature is below this
value.
Idle speed

 The speed the fan is at when the temperature is
between the idle range and set point temperatures
 Temperature in °F/°C, range: 14.0 to 122.0°F, –10.0 to 50.0°C
 Idle speed in %; range: 0 to 100 %
If you need to connect more cooling elements than you have relays available and
you have an unused variable stage, you can use it as an ON/OFF stage (for 115/230
VAC-powered equipment only).
 Set the idle speed to 100% and idle range to the temperature at which you want
the stage to switch on/off.
 You no longer have variable speed or power; you have either full on or full off, the
same as a cooling relay. The set point and differential settings have no effect
when you use a variable stage this way.
 The set point and differential must be greater than the idle range.