Product Manual AGR-3
AGR 070A through 100A
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
225 psig (1552 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 an available option.
On Model AGR
AM units the evaporator is shipped separate for field mounting and piping to the outdoor unit.
The refrigerant specialties shown in Figure 1 (dotted lines) must be purchased from McQuay with the unit and
installed by the installing contractor.
NOTE:
The remote evaporator option is available on R-22 application only and is outside ARI certification.
Figure 1, AGR ---AM, Remote Evaporator Piping (One of two circuits shown)
NOTE:
A water flow switch or both water flow switch and water pump starter interlock, must be field installed to
protect against evaporator freeze-up under low water flow conditions.
