Specifications

15
JOHNSON CONTROLS
Form 201.28-NM1.EN.PED/CE (0211)
2
SEMI-HERMETIC YORK TWIN-SCREW
COMPRESSORS
Compressors are direct drive, semi-hermetic, 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, accessible
hermetic compressor motor, full suction gas flow
through mesh screen filter, with inherent internal thermal
overload protection and external current overload on all
three phases.
Continuous function, microprocessor controlled,
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 associated
unloading components has resulted in a 50% reduction 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, minimize
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
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 aluminium
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 43 bar.
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 fibre reinforced composite
blades moulded 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 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 reliable
and leak resistant system.
• Discharge lines are provided with a manual
compressor shutoff service valve (See Options and
Accessories for suction line service 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 absorption
removable core fi lter-drier, sight glasses with
moisture indicators, manual shut-off valve with
charging port, orifi ce and electronic expansion
valve.
• An economizer (fl ash) tank is located in each
refrigerant circuit to increase the system effi ciency.
The design working pressure is 31 bar.
ELECTRICAL
YORK has over 25 years of experience designing variable
-speed drives specifically for chiller applications. The
result is an extremely reliable air-cooled chiller system
that offers industry leading efficiency at real world
operating conditions, valve-less compressor loading/
unloading, excellent capacity control, 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,
microcomputer 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 servicing.
The panel includes a control display access door so that
display and control features can be accessed without
opening main cabinet doors.
All exposed power wiring is routed through liquid-tight,
UV-stabilized, non-metallic conduit.