York YCIV, Manual

Page: 76 / 80

JOHNSON CONTROLS 76
FORM 201.23-EG2 (713)
Guide Specifications
controls including capacity controller, control center,
motor starting components, and special features as
specified herein or required for safe, automatic opera-
tion.
C. Operating Characteristics:
1. Provide low ambient control and high ambient
options as required to ensure unit is capable
of operation from 0°F to 125°F (-18°C to 52°C)
ambient.
2. Provide capacity control system capable of re-
ducing unit capacity to (10% for 2 compressor
units, 7.5% for 3 compressor units, and 5% for 4
compressor units) of full load. Compressor shall
start in unloaded condition. Application of factory
installed hot gas bypass shall be acceptable as
required to meet specified minimum load.
D. Cabinet: Unit panels, structural elements, control
boxes and heavy gauge structural base shall be
constructed of galvanized steel. Unit panels, control
boxes and structural base are finished with a baked
on powder paint. All painted surfaces shall be coated
with baked on powder paint which, when subject to
ASTMB117, 1,000 hour, 5% salt spray test, yields
minimum ASTM 1654 rating of “6”.
E. Unit shall ship in one piece and shall require installer
to provide only a single evaporator inlet and outlet pipe
connection. If a chiller model that ships in multiple
pieces is provided, bid shall include all the material
and field labor costs for factory authorized personnel
to install a trim kit to connect the pieces as well as all
interconnecting piping and wiring.
2.02 COMPRESSORS AND MOTORS
A. Compressors: Shall be direct drive, semihermetic,
rotary twin-screw type, including: muffler, temperature
actuated ‘off-cycle’ heater, rain-tight terminal box, dis-
charge shut-off service valve, and precision machined
cast iron housing mounted on elastomeric isolators.
Design working pressure of entire compressor, suction
to discharge, shall be 350 psig (24 barg) or higher.
Compressor shall be U.L. recognized.
B. Motors: Refrigerant suction-gas cooled accessible
hermetic compressor motor, full suction gas flow
through 0.006” maximum mesh screen, with inherent
internal thermal overload protection and external cur-
rent overload on all three phases.
C. Lubrication: External oil separators with no moving
parts, 450 psig design working pressure, and UL listing
are provided on the chiller. Refrigerant system differ-
ential pressure shall provide oil flow through service
replaceable, 0.5 micron, full flow, cartridge type oil filter
internal to compressor. Filter bypass, less restrictive
media, or oil pump not acceptable.
D. Capacity Control: Compressors shall start at minimum
load. Provide Microprocessor control to command
compressor capacity to balance compressor capacity
with cooling load. When required to meet minimum
load, hot gas bypass shall be factory installed and
integrated into standard control system.
2.03 REFRIGERANT CIRCUIT COMPONENTS
A. Each independent refrigerant circuit shall include:
liquid line shutoff valve with charging port, low side
pressure relief device, removable core filter-drier, sight
glass with moisture indicator, and electronic expansion
valve (EEV).
B. Chiller manufacturer shall provide independent circuit
for each compressor to provide maximum redundancy
during chiller operation. If equipment does not have
independent circuits per compressor, manufacturer
shall provide owner one spare compressor of each
unique size.
C. Discharge lines shall be provided with manual com-
pressor shutoff service valves. Suction line shall be
covered with closed cell foam insulation.
2.04 HEAT EXCHANGERS
A. Evaporator:
1. Direct expansion type or flooded type shell and
tube evaporator with high efficiency copper
tubes. Independent refrigerant circuits shall be
provided per compressor.
2. Constructed, tested, and stamped IAW appli-
cable sections of ASME pressure vessel code
for minimum 235 psig (16 barg) refrigerant side
design working pressure and 150 psig (10 barg)
water side design working pressure.
3. Shell covered with 3/4” (19mm), flexible, closed-
cell insulation, thermal conductivity of 0.26k
(BTU/HR-Ft
2
-°F/in.) maximum. Water nozzles
with grooves for mechanical couplings, and
insulated by Contractor after pipe installation.
4. Provide vent and drain fittings, and thermo-
statically controlled heaters to protect to -20°F
(-29°C) ambient in off-cycle.
B. Air-cooled Condenser:
1. Coils: Internally enhanced, seamless copper
tubes, mechanically expanded into aluminum