18 • Refrigeration
REfRIgERATION
glycol cases typically have a balance valve located in the outlet line inside of the case. If a stop solenoid is provided, it will also be located in
the outlet line. Schrader valves are provided inside the case on the right-hand side of the coil for venting and draining the system.
Operation Set Points
Refer to the case spec sheet for btu/h requirements and electrical requirements. Operate the case at the proper settings to maintain product
temperature of 41°F or below, per food safety regulations (
Note: Set points based on flat shelves. Alternate shelving—
such as angled or tiered shelving, peg hooks, or produce inserts—may require lower operating temperatures.
Off-Cycle Defrost
for off-cycle defrost settings. During off-cycle defrost, refrigerant is stopped either by stopping the compressor or by closing the
liquid line solenoid valve and allowing the compressor to pump down. The fans and lights remain on during off-cycle defrost.
If temperature termination is selected, set the termination temperature at 45°F for discharge air and coil temperature.
Note: Stocking or
shopping during off-cycle defrost may cause premature defrost termination.
Case Thermometer
The cases are shipped with two thermometers. One thermometer is factory-mounted in the center ceiling pocket cover to sense the discharge
air stream. The second thermometer is shipped loose and should be installed in the warmest product location as required by NSF. Specific field
installation instructions are packaged with the thermometer that is shipped loose.
FIGURE 34: Defrost Settings
SETTING
MEAT
DAIRY/DELI/PRODUCE
BEVERAGE
Defrost Type
Off-Cycle
Off-Cycle
Off-Cycle
Frequency
4 Per Day
4 Per Day
4 Per Day
Duration
36 Minutes
30 Minutes
30 Minutes
FIGURE 33: Case Temperature Internal Control Options (R-404A)
SETTING
MEAT
DAIRY/DELI/PRODUCE
BEVERAGE
Evaporator Temperature
22°F
26°F
28°F
Condensing Unit Cut-In
62 psig
67 psig
71 psig
Condensing Unit Cut-Out
54 psig
59 psig
62 psig
Return Air Temperature Cut-In
44°F
48°F
50°F
Return Air Temperature Cut-Out
40°F
44°F
46°F
Discharge Air Temperature Cut-In
31°F
35°F
37°F
Discharge Air Temperature Cut-Out
27°F
31°F
33°F
Superheat Setting
6-8°F
6-8°F
6-8°F
Note: For high-glide refrigerants, use dew point for unit sizing. Adjust evaporator pressure as needed to maintain
discharge air temperatures. To receive the full benefit of high-glide refrigerant properties, the superheat may need to
be lowered to 4-6°F. Contact Zero Zone with questions.
