Zero Zone Highlight MERCHANDISER RHCC30 - Temperature Control Adjustment; Leak Check, Evacuation, and Charging; Electrical Connections

12 • Installation & Operation
INSTALLATION & OpERATION
The best location for the liquid line drier is inside the case compartment. However, it may be installed near the compressor for easy
maintenance. Install moisture indicating sight glass at the outlet end of the drier.
A low pressure or temperature control can be used to control case temperature. The control should be selected with adequate contact capacity
for the switching load. In rack systems, an evaporator pressure-regulating valve may be used to control the evaporating temperature.
The settings are approximate due to variations in gauge accuracy, differences in compressor efciency, line pressure drop, and superheat
settings. See Figure 22 on page 37. Before making adjustments for store or stocking conditions, make sure the superheat is set.
Close coupled systems typically run at the higher end of this range to avoid ood back.
TEMPERATURE CONTROL ADJUSTMENT
When factory-installed, the temperature control is located toward the right end of the case in the electrical enclosure. The sensing bulb is
located under the coil cover inside the fan shroud. It can be wired in series with the low-pressure (L.P.) control. It can also be used in a pump
down system by wiring it in series with the liquid line solenoid valve. See Figure 23 on page 37 for a thermostat.
Discharge air temperature probes for electronic case controllers may be installed in many different customer-specied locations including, but
not limited to, honeycomb, ceiling pocket cover, rear wall, and return air.
LEAK-CHECK/EVACUATION/CHARGING
After all of the refrigeration piping and system components have been assembled, the entire system must be pressurized and checked for leaks.
When the system is leak free, evacuate with a deep vacuum pump. Triple evacuation to a maximum of 500 microns and nitrogen sweep is
recommended. After the system has been thoroughly evacuated of all moisture and non condensable gas, charge the system with the proper
refrigerant, using “hi-side/low-side” charging techniques.
Do not exceed UL low side pressure rating when pressure testing Zero Zone cases.
Electrical
!
CAUTION! DISCONNECT POWER TO THE CASE BEFORE SERVICING ELECTRICAL COMPONENTS TO AVOID PERSONAL
INJURY AND DAMAGE TO THE UNIT.
For the typical wiring diagram for a low temperature case equipped with electric defrost See Figure 27 on page 41. For the typical wiring
diagram for a low temperature case equipped with hot gas defrost See Figure 28 on page 42. For the typical wiring diagram for a medium
temperature case See Figure 31 on page 45. Each case is provided with a wiring diagram located in the electrical enclosure that shows the
exact wiring of the case.
There are many control options available for multiple case defrost systems. Wiring diagrams and instructions can be obtained by contacting
Zero Zone’s Service Department.
External wiring should be sized according to the amperage rating indicated on the serial plate. The serial plate is located on the ceiling inside
the left-hand door. Typical electrical values for each of these cases are shown on specication sheets in the bag attached to the case or are
available at www.zero-zone.com. All internal wiring has been done at the factory. Cases with standard wiring have their control wires terminated
in the electrical enclosure located behind the kick rail at the right end of the case. A terminal block has been used to simplify eld connections.
An electrical box is mounted on the top of the unit for cases equipped with the optional top mount electrical connections.
All wiring must comply with the National Electrical Code and all local codes. After installation of the equipment, correct operation of the electrical
circuits and controls and defrost operation and termination should be veried. All operating voltages and amperages should be measured and
recorded.