Semi-Hermetic York Twin-Screw Compressors; Evaporator; Condenser; Refrigerant Circuit - York YVAA Installation, Operation & Maintenance Instructions Manual

FORM 201.28-NM1.1
ISSUE DATE: 1/31/2018
SEMI-HERMETIC YORK TWIN-SCREW
COMPRESSORS
Compressors are direct drive, semi-hermetic amd
rotary twin-screw type, including: muffler, temperature
actuated 'off-cycle' heater, IP55 terminal board and
precision 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
Variable Speed Drive (VSD) shall 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 shell and tube, hybrid falling film
type heat exchanger. It contains a balance of flooded
and falling film technology to optimize efficiency, min-
imize refrigerant charge, and maintain reliable control.
A specifically designed distribution system provides
uniform refrigerant flow for optimum performance.

CONDENSER

The YVAA introduces micro-channel coil to the York
screw compressor chiller line. The micro-channel max-
imizes 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 sub-cooling
is included. The design working pressure is 375 PSIG
(25.9 barg).
Multiple, standard low sound, high efficiency, TEAO
motor driven fans move air through the coils. They are
dynamically and statically balanced, direct drive with
corrosion-resistant glass fiber reinforced composite
blades molded into low-noise, full airfoil cross sec-
tions, providing vertical air discharge from extended
orifices for efficiency and low sound.
JOHNSON CONTROLS
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 maintenance
cost over the life of the unit.

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.
controlled, • Discharge lines are provided with a manual com-
pressor shutoff service valve See "Accessories
and Options" on page 21 for suction line ser-
vice 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-
tion removable core filter-drier, sight glasses with
moisture indicators, manual shut-off valve with
charging port, orifice and electronic expansion
valve.
• An economizer (flash) tank is located in each re-
frigerant circuit to increase the system efficiency.

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, 115VAC 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-
out opening main cabinet doors. All exposed power
wiring is routed through liquid-tight, UV-stabilized,
non-metallic conduit.
SECTION 2 - PRODUCT DESCRIPTION
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