YZ Engineering Guide
Form: 161.01-EG1 (0618)
19
connections. If desired, vent and drain valves may be installed with or without piping to an open drain. Pressure gauges
with stop-cocks and stop-valves may be installed in the inlets and outlets of the condenser and chilled water line as close
as possible to the chiller. An overhead monorail or beam may be used to facilitate servicing.
Connections
- The standard chiller is designed for 1034 kPa (150 psig) design working pressure in both the chilled
water and condenser water circuits. The connections (water nozzles) to these circuits are furnished with grooves to
ANSI/AWWA C-606 standard for grooved and shouldered joints. Piping should be arranged for ease of disassembly at
the unit for tube cleaning. All water piping should be thoroughly cleaned of all dirt and debris before final connections are
made to the chiller.
Chilled Water
- A water strainer of maximum 3.2 mm (1/8") perforated holes must be field-installed in the chilled water
inlet line as close as possible to the chiller. If located close enough to the chiller, the chilled water pump may be protected
by the same strainer. The strainer is important to protect the chiller from debris or objects which could block flow through
individual heat exchanger tubes. A reduction in flow through tubes could seriously impair the chiller performance or even
result in tube freeze-up. A flow switch is factory installed in the evaporator nozzle and connected to the OptiView
™ panel,
which assures adequate chilled water flow during operation.
Condenser Water
- The chiller is engineered for maximum efficiency at both design and part load operation by taking
advantage of the colder cooling tower water temperatures which naturally occur during the winter months. Appreciable
power savings are realized from these reduced heads. At initial startup, entering condensing water temperature may be
as much as 16.7°C (30°F) colder than the standby chilled water temperature.
MULTIPLE UNITS
Selection
-
Many applications require multiple units to meet the total capacity requirements as well as to provide flexibility
and some degree of protection against equipment shutdown. There are several common unit arrangements for this type
of application. The YZ chiller has been designed to be readily adapted to the requirements of these various arrangements.
Parallel Arrangement
-
Chillers may be applied in multiples with chilled and condenser water circuits connected in
parallel between the units. Figure 1 below represents a parallel arrangement with two chillers. Parallel chiller
arrangements may consist of equally or unequally sized units. When multiple units are in operation, they will load and
unload at equal percentages of design full load for the chiller.
Figure 1
– Parallel Evaporators (Evap.) Parallel Condensers (Cond.)
Cond. 1
Evap. 1
Cond. 2
Evap. 2
T
S1
S2
T
S
- Thermostat for Chiller Capacity Control
- Temperature Sensor for Chiller Capacity Control