User Guide

9
Solenoid valves are used for controlling refrigerants in liquid or suction lines
or in hot-gas lines. Some common applications for solenoid valves are:
Pump-down cycle
Temperature control of separate units in a multiple system
Suction applications
Compressor unloading
•Hot-gas bypass
Hot-gas defrost
Introduction
In the pump-down cycle application, the solenoid valve is installed in the
main liquid line and wired so that it closes whenever the thermostat is
satisfied. A low-pressure control valve allows the refrigerant in the evaporator
to be “pumped down” (see Figure 7).
Pump-down cycle
Note: This type of cycle is ideal in systems with large charges, because it prevents the
possibility of the compressor starting with a large amount of liquid in the evaporator.
Figure 8 illustrates how the temperature of a single unit in a multiple system
can be controlled by a thermostat operating a solenoid valve in the liquid line
to that unit.
Temperature control
of separate units in a
multiple system
Solenoid-valve applications
Pump-Down Cycle
Figure 7
Multiple Systems
Figure 8
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