PKGP-PRC003-EN
53
Mechanical
Specifications
General
The units shall be convertible airflow. The
operating range shall be between 115°F
and 0°F in cooling as standard from the
factory for units with microprocessor
controls. Operating range for units with
electromechanical controls shall be
between 115°F and 40°F. Cooling
performance shall be rated in accordance
with ARI testing procedures. All units shall
be factory assembled, internally wired,
fully charged with R-22, and 100 percent
run tested to check cooling operation, fan
and blower rotation, and control
sequence before leaving the factory.
Wiring internal to the unit shall be colored
and numbered for simplified
identification. Units shall be UL listed and
labeled, classified in accordance to UL
1995/CAN/CSA No. 236-M90 for Central
Cooling Air Conditioners. Canadian units
shall be CSA Certified.
Casing
Unit casing shall be constructed of zinc
coated, heavy gauge, galvanized steel.
Exterior surfaces shall be cleaned,
phosphatized, and finished with a
weather-resistant baked enamel finish.
Unit’s surface shall be tested 1000 hours
in a salt spray test in compliance with
ASTM B117. Cabinet construction shall
allow for all maintenance on one side of
the unit. Service panels shall have lifting
handles and be removed and reinstalled
by removing only a single fastener while
providing a water and air tight seal. All
exposed vertical panels and top covers in
the indoor air section shall be insulated
with a cleanable foil-faced, fire-retardent
permanent, odorless glass fiber material.
The base of the unit shall be insulated
with 1/2 inch, 1 pound density foil-faced,
closed-cell material. All insulation edges
shall be either captured or sealed.The
unit’s base pan shall have no penetrations
within the perimeter of the curb other
than the raised 1
1
/
8
inch high downflow
supply/return openings to provide an
added water integrity precaution, if the
condensate drain backs up. The base of
the unit shall have provisions for forklift
and crane lifting, with forklift capabilities
on three sides of the unit.
Unit Top
The top cover shall be one piece
construction or where seams exist, it
shall be double-hemmed and gasket-
sealed. The ribbed top adds extra
strength and prevents water from
pooling on unit top.
Filters
One inch, throwaway filters shall be
standard on all 3-5 ton units. The filter rack
can be converted to two inch capability.
Two inch filters shall be factory supplied
on all 6-10 ton units. Optional 2-inch
pleated filters shall be available.
Compressors
All 3 ton standard units shall have direct-
drive, hermetic, reciprocating type
compressors. The reciprocating type
compressors have a centrifugal oil pump
providing positive lubrication to moving
parts. Motor shall be suction gas-cooled
and shall have a voltage utilization range
of plus or minus 10 percent of unit
nameplate voltage. Crankcase heater,
internal temperature, and current-
sensitive motor overloads shall be
included for maximum protection.
Compressors shall have internal spring
isolation and sound muffling to minimize
vibration transmission and noise. Low
pressure switches shall be standard.
3 ton high efficiency and 4-10 ton
standard and high efficiency units shall
have direct-drive, hermetic, scroll type
compressors with centrifugal type oil
pumps. Motor shall be suction gas-cooled
and shall have a voltage utilization range
of plus or minus 10 percent of unit
nameplate voltage. Internal overloads
shall be provided with the scroll
compressors. Crankcase heaters shall be
included on 7½ ton standard efficiency
units.
Refrigerant Circuits
Each refrigerant circuit offers a choice of
independent fixed orifice expansion
devices or thermal expansion valve.
Service pressure ports, and refrigerant
line filter driers are factory-installed as
standard. An area shall be provided for
replacement suction line driers.
Evaporator and Condenser Coils
Internally finned, 5/16” copper tubes
mechanically bonded to a configured
aluminum plate fin shall be standard.
Coils shall be leak tested at the factory to
ensure the pressure integrity. The
evaporator coil and condenser coil shall
be leak tested to 200 psig and pressure
tested to 450 psig. The condenser coil
shall have a patent pending 1+1+1 hybrid
coil designed with slight gaps for ease of
cleaning. A removeable, reversible,
double-sloped condensate drain pan with
provision for through the base
condensate drain is standard.
Outdoor Fans
The outdoor fan shall be direct-drive,
statically and dynamically balanced,
draw-through in the vertical discharge
position. The fan motor shall be
permanently lubricated and shall have
built-in thermal overload protection.
Indoor Fan
All 3-5 ton 3-phase units offer a choice of
direct-drive, FC, centrifugal fans or belt
driven, FC centrifugal fans with
adjustable motor sheaves. 3-5 ton direct
drive oversized motors shall be available
for high static operations. All 6-10 ton
units shall have belt drive motors with an
adjustable idler-arm assembly for quick-
adjustment to fan belts and motor
sheaves. All motors shall be thermally
protected. All indoor fan motors meet the
U.S. Energy Policy Act of 1992 (EPACT).
Controls
Unit shall be completely factory-wired
with necessary controls and contactor
pressure lugs or terminal block for power
wiring. Unit shall provide an external
location for mounting a fused disconnect
device. Microprocessor controls provide
for all 24 volt control functions. The
resident control algorithms shall make all
heating, cooling, and/or ventilating
decisions in response to electronic signals
from sensors measuring indoor and
outdoor temperatures. The control
algorithm maintains accurate
temperature control, minimizes drift from
set point, and provides better building
comfort. A centralized Microprocessor
shall provide anti-short cycle timing and
time delay between compressors to
provide a higher level of machine
protection.
