60
SSP-PRC001-EN
Heat Pumps
General
Units shall be assembled on heavy
gauge steel mounting/lifting rails
and shall be weather proofed. Unit
shall include a hermetic scroll or
reciprocating compressor(s), plate
fin condenser coil, fans and motors,
controls and holding charge of
nitrogen. Operating Range shall be
between 115°F to 50°F in cooling as
standard from factory. Units shall be
UL 1995 listed and rated in
accordance with ARI Standard 340/
360.
Casing
Unit casing shall be constructed of
18 gauge zinc coated heavy gauge,
galvanized steel. Exterior surfaces
shall be cleaned, phosphatized and
finished with a weather-resistant
baked enamel finish. Units surface
shall be tested 500 hours in salt
spray test. Units shall have
removable end panels which allow
access to all major components and
controls.
Refrigeration System —
Single Compressor
TWA090A, TWA120A units shall
have a single refrigeration circuit.
Each refrigeration circuit has an
integral subcooling circuit. A
refrigeration filter drier, expansion
valve and check valves shall be
provided as standard.
The TWA090A, TWA120A units shall
have both a liquid line and suction
gas line service valve with gauge
port. TWA090A, TWA120A units shall
have one direct drive Trane hermetic
scroll compressor with 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
nameplate voltage. Crankcase
heater, internal temperature and
current-sensitive motor overloads
shall be included for maximum
protection. Scroll type compressor
shall provide inherently low
vibration and noise by having no
suction and discharge valves.
External high and low pressure
cutout devices shall be provided.
Evaporator defrost control provided
in indoor blower coil unit shall
prevent compressor slugging by
temporarily interrupting compressor
operation when low evaporator coil
temperatures are encountered.
Refrigeration System — Dual
Compressor
TWA180B, TWA240B units shall have
two separate and independent
refrigeration circuits. Each
refrigeration circuit shall have an
integral subcooling circuit. A
refrigeration filter drier shall be
provided as standard.
Units shall have both a liquid line
and suction gas line service valve
with gauge ports. TWA180B,
TWA240B units shall have two Trane
direct drive hermetic scroll
compressors with centrifugal oil
pump and provide positive
lubrication to all moving parts.
Motor shall be suction gas-cooled
and shall have a voltage utilization
range of plus or minus 10 percent of
nameplate voltage. Crankcase
heater, internal temperature and
current-sensitive motor overloads
shall be included for maximum
protection. Scroll type compressor
shall provide inherently low
vibration and noise by having no
suction and discharge valves.
External high and low pressure
cutout devices shall be provided.
Evaporator defrost control provided
in indoor blower coil shall prevent
compressor slugging by temporarily
interrupting compressor operation
when low evaporator coil
temperatures are encountered.
Condenser Coil
Coils shall be internally finned or
smooth bore 3/8" copper tubes
mechanically bonded to configured
aluminum plate fin as standard. Coil
shall be factory pressure and leak
tested to 420 psig air pressure. Metal
grilles with PVC coating for coil
protection is optional.
Condenser Fan and Motor(s)
Direct-drive, statically and
dynamically balanced 26 or 28 inch
propeller fan(s) with aluminum
blades and electro-coated steel hubs
shall be used in draw-through
vertical discharge position. Either
permanently lubricated totally
enclosed or open construction type
motors shall be provided and shall
have built in current and thermal
overload protection. Motor(s) shall
have either ball or sleeve bearing
type.
Controls
Heat pump units shall be completely
factory wired with necessary
controls and contactor pressure lugs
or terminal block for power wiring.
Control wiring shall be 24-volt
control circuit which includes fusing
and control transformer. Units shall
provide external location for
mounting a fused disconnect device.
Time delay timers to prevent
compressors in dual compressor
units from simultaneous start-up and
anti-recycle timers are available as
optional accessories.
Defrost Controls
Electronic timed initiated,
temperature terminated defrost
system with choice of 50, 70, or 90
minute cycle. Timed override limits
defrost cycle to 10 minutes.
Low Ambient Operation
Standard units shall start and
operate to approximately 50°F when
matched with Trane air handlers and
coils. Optional head pressure control
accessory permits operation to 0°F.
Accessories
Low Ambient Head Pressure
Control
— Shall modulate the RPM
of unit outdoor fan motor in
response to outdoor ambient
temperatures and liquid line
temperature. Accessory provides
unit cooling operation to outdoor
temperatures of 0°F.
Vibration Isolation Packages
—
Shall reduce transmission of noise
Mechanical Specifications
