Fig. 12 - Multiple Units (Two) - Parallel Operation - Individual Pumps; Fig. 13 - Multiple Units (Two) - Parallel Operation - Single Chilled Water Pump; Fig. 14 - Electro-Mechanical Starter Manual Reset Overloads - York MILLENNIUM YT J Wiring Diagram

FIG. 12 – MULTIPLE UNITS (TWO) – PARALLEL
OPERATION – INDIVIDUAL UNIT PUMPS
FIG. 12 – MULTIPLE UNITS (TWO) – PARALLEL
OPERATION – INDIVIDUAL UNIT PUMPS
This piping arrangement is the same as Fig. 13, except
that the chilled water pumps associated with each cooler
(evaporator) are cycled on and off with the unit. This
results in reduced chilled water flow rates whenever a
single unit can handle the cooling load. Because no
chilled water flows through the inoperative unit, the
mixed water temperature peculiar to using a single pump
is avoided. When one unit is cut-out by the sequence
control (Fig. 10) the temperature of the supply chilled
water does not change.
FIG. 14 –ELECTRO-MECHANICAL STARTER
MANUAL RESET OVERLOADS (2300 to
4160 Volts U.L. or C.S.A. approved units
only)
YORK INTERNATIONAL
LD04394
FIG. 13 – MULTIPLE UNITS (TWO) – PARALLEL
OPERATION – SINGLE CHILLED WATER
PUMP
FIG. 13 – MULTIPLE UNITS (TWO) – PARALLEL OP-
ERATION – SINGLE CHILLED WATER PUMP
For this piping arrangement, each chiller's water sensor
is located in its own leaving water nozzle. This produces
a constant "mixed" chilled water temperature when both
units are operating. When either unit is cycled off by
the sequence control (Fig. 10), mixed chilled water
temperature will rise as a result of uncooled return wa-
ter flowing through the inoperative unit. For individual
unit chilled water pump piping, refer to Fig. 12.
FIG. 14 – ELECTRO-MECHANICAL STARTER
MANUAL RESET OVERLOADS
Terminals are available for connection of the manual
reset overloads and/or safety devices in the high volt-
age electro-mechanical starter for U.L. or C.S.A. ap-
proved units having 2300 to 4160 volt motors. See Re-
mote Motor Starter (E-M) specifications, Product Draw-
ing Form 160.45-PA5.1. An opening of the contacts
causes the Graphic Control Center to display: "CY-
CLING SHUTDOWN – AUTO RESTART" and "MO-
LD04388
TOR CONTROLLER – CONTACTS OPEN". To re-
start the chiller, reset the external device in the
electro-mechanical starter that caused the shutdown.
Then the unit will automatically restart.
FORM 160.55-PW7
LD04395
9