JOHNSON CONTROLS
17
Form 201.47-ICOM1
Issue date: 17/11/2022
SECTION 2 - PRODUCT DESCRIPTION
2
Semi-hermetic YORK twin-screw
compressors
Compressors are direct drive, semi-hermetic and
rotary twin-screw type, including: muffler, temperature
actuated off-cycle heater, IP55 terminal board, and pre-
cision machined cast iron housing.
Reliable suction gas cooled, high efficiency, acces-
sible hermetic compressor motor, full suction gas flow
through mesh screen filter, with inherent internal ther-
mal overload protection and external current overload
on all three phases.
Continuous function, microprocessor controlled,
variable speed drive (VSD) must provide valve-less,
smooth capacity control from 100% down to 10% of
chiller capacity.
In addition, elimination of the slide valve and associ-
ated unloading components has resulted in a 50% re-
duction in compressor moving parts.
Evaporator
The evaporator is a two-circuit, series counterflow
shell and tube, hybrid falling film type heat exchanger.
It contains a balance of flooded and falling film tech-
nology to optimize efficiency, minimize refrigerant
charge, and maintain reliable control. A specifically
designed distribution system provides uniform refrig-
erant flow for optimum performance.
Condenser
The YVAA Style B introduces next-gen 4G microchan-
nel coils to the YORK screw compressor chiller line.
This design allows for bigger flow channels, reducing
refrigerant pressure drop by three to four times and
improving condenser performance. The microchan-
nel maximizes condenser heat transfer, resulting in a
smaller footprint, and reduces refrigerant charge by as
much as 50%.
Each condenser coil is a single piece all aluminum
construction including headers, tubes and fins to avoid
galvanic corrosion due to dissimilar metals. Coils and
headers are brazed as one piece. Integral subcooling
is included. The design working pressure is 375 psig
(25.9 barg).
Multiple, standard low sound, high efficiency, variable
speed drive motor driven fans move air through the
coils. They are dynamically and statically balanced,
direct drive with corrosion-resistant glass fiber rein-
forced composite blades molded into low-noise, full
airfoil cross sections, providing vertical air discharge
from extended orifices for efficiency and low sound.
Fan motors are totally enclosed air-over (TEAO),
squirrel-cage type and current protected. The direct
drive motors feature double-sealed and permanently
lubricated ball bearings, cutting down on mainte-
nance cost over the life of the unit. The chiller is also
equipped with the option of variable speed electroni-
cally commutated (EC) motors to provide extra airflow
across coils with lower power consumption, resulting
in higher efficiencies.
Refrigerant circuit
An independent refrigerant circuit is provided per
compressor. Each circuit uses copper refrigerant pipe
formed on computer controlled bending machines to
reduce the number of brazed joints resulting in a reli-
able and leak resistant system.
• Discharge lines are provided with a manual com-
Accessories and
Options on page 19, for service isolation valve.
• The external oil separators, with no moving parts
and designed for minimum oil carry-over, are
mounted in the discharge line of the compressor.
• Liquid line components include: high absorp-
valve.
• A brazed plate heat exchanger is located in each
-
cy.
Electrical
Johnson Controls has over 25 years of experience de-
signing variable-speed drives specifically for chiller
applications. The result is an extremely reliable air-
cooled chiller system that offers industry leading ef-
ficiency at real world operating conditions, valve-less
compressor loading/unloading, excellent capacity con-
trol, high power factor and soft start.
Incoming single point power is standard utilizing a
lockable circuit breaker, 115 VAC control transformer,
VSD, fan contactors, ON/OFF unit switch, microcom-
puter keypad and display, Chiller Control and VSD
Logic boards, and relay boards.
Standard design includes IP55 rating, powder painted
steel cabinet with hinged, latched, and gasket sealed
outer doors equipped with wind struts for safer servic-
ing. The panel includes a control display access door so
that display and control features can be accessed with-
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