99
RT-PRC010-EN
General
Units shall be specifically designed for
outdoor rooftop installation on a roof
curb and be completely factory
assembled and tested, piped, internally
wired, fully charged with R-22,
compressor oil and shipped in one piece.
Units shall be available for direct
expansion cooling only, or direct
expansion cooling with natural gas,
electric, hot water or steam heating.
Filters, outside air system, exhaust air
system, optional non-fused disconnect
switches and all operating and safety
controls shall be furnished
factoryinstalled. All units shall be UL
approved and factory run tested. Cooling
capacity shall be rated in accordance
with ARI Standard 360. All units shall
have decals and tags to aid in service
and indicate caution areas. Electrical
diagrams shall be printed on long life
water resistant material and shall ship
attached to control panel doors.
Casing
Exterior panels shall have a minimum of
1.25-ounce zinc coating per square foot
of steel, phosphatized and painted with a
slate grey finish which meets a 672 hour
salt spray test based on the ASTM B117
standard for salt spray resistance.
Screws shall be coated with zinc-plus-
zinc chromate. Eighteen gauge steel
hinged access panels with tiebacks to
secure door in open position shall
provide access to filters and heating
sections. Refrigeration components,
supply air fan and compressor shall be
accessible through removable panels as
standard. Unit control panel shall be
accessible through hinged access panel
with quick release latches. Double Wall
Construction hinged access doors shall
provide access to filters, return/exhaust
air, heating and supply fan section. All
access doors and panels shall have
neoprene gaskets. Interior surfaces or
exterior casing members shall have
1
/
2
-
inch Tuf-Skin fiberglass insulation. Unit
base shall be watertight with 14-gauge
formed load bearing members, formed
recess and curb overhang. Unit lifting
lugs shall accept chains or cables for
rigging. Lifting lugs shall also serve as
unit tiedown points.
Mechanical
Specifications
REFRIGERATION SYSTEM
Compressors
20 to 130 Ton Units
Trane 3-D
®
Scroll compressors have a
simple mechanical design with only
three major moving parts. Scroll type
compression provides inherently low
vibration. The 3-D Scroll provides a
completely enclosed compression
chamber which leads to increased
efficiency. Exhaustive testing on the 3-D
Scroll, including start up with the shell
full of liquid, has proven that slugging
does not fail involutes. Direct-drive, 3600
rpm, suction gas-cooled hermetic motor.
Trane 3-D Scroll compressor includes
centrifugal oil pump, oil level sightglass
and oil charging valve. Each compressor
shall have crankcase heaters installed,
properly sized to minimize the amount of
liquid refrigerant present in the oil sump
during off cycles. Discharge and liquid
line service valves are standard on each
refrigerant circuit.
Evaporator Coil
Internally enhanced copper tubing of ½-
inch O.D. shall be mechanically bonded
to heavy-duty aluminum fins of
configurated design. All coils shall be
equipped with thermal expansion valves
and factory pressure and leak tested at
300 psi.
Condenser Coil
Configurated aluminum fin or
configurated copper fin secondary
surface shall be mechanically bonded to
primary surface of
3
/
8
-inch O.D. copper
tubing for extra corrosion resistance.
Subcooling circuit(s) shall be provided as
standard. All coils shall be factory
tested at 450 psig air pressure and
vacuum dehydrated.
Condenser Fans and Motors
All condenser fans shall be vertical
discharge, direct drive fans, statically
balanced, with steel blades and zinc
plated steel hubs. Condenser fan motors
shall be three-phase motors with
permanently lubricated ball bearings,
built-in current and thermal overload
protection and weathertight slingers
over motor bearings.
