supplies requiring temperatures between 30F and 45F. Standard-size units most frequently used are those with storage capacities between 15 and 85 cubic feet. Figure 6-34 shows a typical reach-in refrigerator with a remote (detached) condensing unit.

Exterior finishes for reach-in refrigerators are usually of stainless steel, aluminum, or vinyl, while the interior finishes are usually metal or plastic, and the refrigerator cabinet is insulated with board or batten type polystyrene or urethane. Reach-in refrigerators are normally self-contained, with an air-cooled condenser, but in larger refrigerators, with remote condensers, water-cooled condensers are sometimes used. A typical self-contained unit is shown in figure 6-35. The evaporator is mounted in the center of the upper portion of the food compartment. In operation, warm air is drawn by the fan into the upper part of the unit cooler, where it passes over the evaporator coils, is cooled, and then is discharged at the bottom of the cooler. The air then passes up through the interior and around the contents of the refrigerator. The cycle is completed when the air again enters the evaporator. The low-pressure control is set to operate the evaporator on a self-defrosting cycle, and temperature is thus control led. Another type of control system uses both temperature and low-pressure control or defrost on each cycle. The evaporator fan is wired for continuous operation within the cabinet.

Figure 6-35. - A self-contained reach-in refrigerator.

Evaporators in reach-in refrigerators are generally the unit cooler type with dry coils (fig. 6-36). In smaller capacity refrigerators, ice-making coils, similar to those used in domestic refrigerators, are often used as well as straight gravity coils. R-12 and R-502 are normally used in these units.

WALK-IN REFRIGERATORS

Walk-in refrigerators are normally larger than reach-in types and are either built-in or prefabricated sectional walk-in units. They are made in two

Figure 6-36. - A. Unit cooler in a reach-in refrigerator; B. Dome cooler in a reach-in refrigerator.