FORM 160.55-O1 (920)
7
YORK INTERNATIONAL
combination Logic/Trigger Board that interfaces the
Control Center with a serial communications link. Ear-
lier vintage chillers, such as those encountered in Control
Center retrofit applications are equipped with the Mod
“A” starter. This Starter contains a Trigger Board that
interfaces to a Logic Board that is installed inside of the
Control Center.
In operation, a liquid (water or brine to be chilled) flows
through the cooler, where boiling refrigerant absorbs heat
from the liquid. The chilled liquid is then piped to fan
coil units or other air conditioning terminal units, where
it flows through finned coils, absorbing heat from the
air. The warmed liquid is then returned to the chiller to
complete the chilled liquid circuit.
The refrigerant vapor, which is produced by the boiling
action in the cooler, flows to the compressor where the
rotating impeller increases its pressure and temperature
and discharges it into the condenser. Water flowing
through the condenser tubes absorbs heat from the refrig-
erant vapor, causing it to condense. The condenser water
is supplied to the chiller from an external source, usually
a cooling tower. The condensed refrigerant drains from
the condenser into the liquid return line, where the vari-
SECTION 1
DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION
29509A
CONDENSER
CONTROL
CENTER
COMPRESSOR
MOTOR
COOLER
FIG. 1 –
MODEL YT MILLENNIUM CHILLER
SYSTEM OPERATION DESCRIPTION (SEE FIG. 2)
The YORK Model YT Millennium Chiller is commonly
applied to large air conditioning systems, but may be
used on other applications. The chiller consists of an
open motor mounted to a compressor (with integral
speed increasing gears) condenser, cooler and variable
flow control.
The chiller is controlled by a modern state of the art
OptiView Control Center that monitors its operation. The
Control Center is programmed by the operator to suit job
specifications. Automatic timed start-ups and shutdowns
are also programmable to suit nighttime, weekends and
holidays. The operating status, temperatures, pressures
and other information pertinent to operation of the chiller
are automatically displayed and read on a graphic mes-
sage display. Other displays can be observed by pressing
the keys as labeled on the Control Center. The chiller
with the OptiView Control Center is applied with an
electro-mechanical starter, YORK Solid State Starter
(optional) or Variable Speed Drive (optional).
There could be either of two different Solid State Start
-
ers applied. New production chillers are equipped with
the Mod “B” Solid State Starter. This starter contains a
1
PURGE
UNIT
