McQuay AGZ 030AM, Product Manual

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Product Manual AGZ-2 AGZ 030A through 065A 5
Evaporator
The evaporator is direct expansion, shell-and-tube type with water flowing in the baffled shell side and
refrigerant flowing through the tubes. Two independent refrigerant circuits within the evaporator
serve the units dual refrigerant circuits.
The evaporator has a carbon steel shell and seamless high efficiency copper tubes roller expanded into
a carbon steel tube sheet. Water baffles are polypropylene to resist corrosion.
Refrigerant heads are carbon steel with multi-pass baffles to ensure oil return and are removable to
permit access to the tubes from either end. For water removal, 3/8" (10mm) vent and drain plugs are
provided on the top and bottom of the shell.
The evaporator is wrapped with an electric resistance heater cable and insulated with 3/4" (19mm)
thick vinyl nitrate polymer sheet insulation, protecting against water freeze-up at ambient air
temperatures to -20°F (-29°C). An ambient air thermostat controls the heater cable.
The fitted and glued in place insulation has a K factor of 0.28 at 75°F (23°C).
The refrigerant (tube) side maximum working pressure is 225 psig (1552 kPa). The water side
working pressure is 175 psig (1207 kPa). Each evaporator is designed, constructed, inspected, and
stamped according to the requirements of the ASME Boiler and Pressure Vessel Code. Double
thickness insulation is available as an option.
On Model AGZ ---AM units the evaporator is shipped separate for field mounting and piping to the
outdoor unit. The refrigeration piping specialties shown in Figure 1 are furnished and installed by the
installing contractor.
NOTE: A water flow switch or both water flow switch and water pump starter interlock, must be
field installed and wired to protect against evaporator freeze-up under low water flow conditions.
Figure 1, AGZ ---AM Remote Evaporator Piping Schematic (one of two circuits
shown)