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FORM 160.55-O1 (604)
7
YORK INTERNATIONAL
combination Logic/Trigger Board that interfaces the
Con trol Center with a serial communications link. Ear-
li er vintage chillers, such as those encountered in Con trol
Cen ter retroÞ t ap pli ca tions are equipped with the Mod
“A” starter. This Start er con tains a Trig ger Board that
in ter fac es to a Logic Board that is in stalled inside of the
Control Cen ter.
In operation, a liquid (water or brine to be chilled) ß ows
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 ß ows through Þ nned 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 boil ing
action in the cooler, ß ows to the compressor where the
rotating impeller increases its pressure and tem per a ture
and discharges it into the condenser. Water ß ow ing
through the condenser tubes absorbs heat from the re frig -
er ant va por, causing it to condense. The con dens er water
is sup plied to the chiller from an external source, usually
a cool ing tower. The condensed re frig er ant drains from
the con dens er 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
ap plied 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 in creas ing gears) condenser, cooler and vari able
ß ow con trol.
The chiller is controlled by a modern state of the art
OptiView Control Center that monitors its op er a tion. The
Control Center is programmed by the op er a tor to suit job
speciÞ cations. Automatic timed start-ups and shut downs
are also programmable to suit night time, week ends and
holidays. The operating status, tem per a tures, pressures
and other information per ti nent to op er a tion of the chiller
are automatically dis played and read on a graphic mes-
sage display. Other displays can be ob served by press ing
the keys as labeled on the Con trol Center. The chill er
with the OptiView Control Cen ter is applied with an
electro-mechanical start er, YORK Solid State Start er
(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