Operation
21
On single and dual digital scroll compressor systems, the first compressor is started at 25% calculated
output from the temperature proportional band and stopped at 10%. On dual digital scroll compressor
systems, the second compressor is started at 35% and stopped at 20%, see Figure 17. When a com-
pressor is started, the solenoid is energized longer than it is de-energized to match the call for cooling.
When the call for cooling increases to 100%, the solenoid is de-energized for the entire 15 second cycle.
Figure 17 Single and dual digital scroll compressor activation points
Temp Setpoint : 70°F
Proportional Band : 8°F
Deadband: 2°F
½ Dead-
band
Increasing Temperature
Comp 1
Off
½ Proportional Band
757473727170
0%
Cooling
+ 100 %
Cooling
Comp 2
Off
Comp 1 On Partially
Loaded
Comp 2 On Partially
Loaded
Comp 1 & 2 On
Fully Loaded
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