Unit installation

16 ACZ / AGZ-BM IOMM ACZ/AGZ-3
Figure 18, AGZ 026BM - AGZ 070BM, Typical Field Evaporator Water Piping
A
ir
Vent
Flow
Switch
Vibration
Eliminators
Drain
Outlet
Inlet
P
Isolation
Valves
Strainer
Thermowell
T
T
Flow Switch (Model AGZ-BM)
Mount a water flow switch in the leaving water line of the remote water chiller to shut down the unit
when water flow is interrupted. A flow switch is an equipment protection control and should never
be used to cycle a unit.
A flow switch is available from McQuay (part number 017503300). It is a “paddle” type switch and
adaptable to any pipe size from 2” (51 mm) to 6” (152 mm) nominal. Certain minimum flow rates
are required to close the switch and are listed in Table 7. Installation should be as shown in Figure
19. Connect the normally open contacts of the flow switch in the unit control center at terminals 44
and 61. There is also a set of normally closed contacts on the switch that can be used for an
indicator light or an alarm to indicate when a “no flow” condition exists. Freeze protect any flow
switch that is installed outdoors. Manufacturer’s instructions included with the switch should be
followed. NOTE: Differential pressure switches are not recommended for outdoor installation.
Table 7, Flow Switch Minimum/Maximum Flow Rates
Nominal Pipe Size
Inches (mm)
Minimum Required Flow To
Activate Switch - gpm (l/m)
Maximum Flow Rate
gpm (l/m)
2 (50.8) 13.7 (51.8) 105 (397.4)
2 1/2 (63.50 17.9 (67.8) 149 (564.0)
3 (76.20 24.2 (91.6) 230 (870.6)
4 (101.6) 35.3 (134.0) 397 (1502.7)
5 (127.0) 48.6 (184.0) 654 (2475.4)
6 (152.4) 60.3 (228.0) 900 (3406.5)
Note: See pressure drop table on page 23 for minimum and maximum flow through the evaporator.
Figure 19, Flow Switch Installation
Water Connections
Bring water piping to the evaporator through the side between the vertical supports. Provide taps for
the connection of pressure gauges and thermometers in the inlet and outlet lines. Check the inlet and
outlet labels on the unit against the certified drawings supplied on the job and be sure the water
piping is hooked up correctly. Contact the McQuay sales office if any discrepancies exist.
Flow direction marked on switch
1" (25mm) NPT flow switch connection
Tee