SSP-PRC001-EN 55
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 reciprocat-
ing compressor(s), plate fin con-
denser coil, fans and motors, controls
and holding charge of nitrogen. Oper-
ating 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, gal-
vanized 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 pan-
els 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 fil-
ter 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 mov-
ing parts. Motor shall be suction gas-
cooled and shall have a voltage utili-
zation range of plus or minus 10 per-
cent of nameplate voltage. Crankcase
heater, internal temperature and cur-
rent-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 pres-
sure 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 tempera-
tures are encountered.
Refrigeration System — Dual
Compressor
TWA180B, TWA240B units shall have
two separate and independent refrig-
eration circuits. Each refrigeration cir-
cuit 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 volt-
age. Crankcase heater, internal tem-
perature and current-sensitive motor
overloads shall be included for maxi-
mum protection. Scroll type compres-
sor shall provide inherently low
vibration and noise by having no suc-
tion 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 pro-
tection is optional.
Condenser Fan and Motor(s)
Direct-drive, statically and dynami-
cally balanced 26 or 28 inch propeller
fan(s) with aluminum blades and elec-
tro-coated steel hubs shall be used in
draw-through vertical discharge posi-
tion. 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 termi-
nal block for power wiring. Control
wiring shall be 24-volt control circuit
which includes fusing and control
transformer. Units shall provide exter-
nal location for mounting a fused dis-
connect device. Time delay timers to
prevent compressors in dual com-
pressor units from simultaneous start-
up and anti-recycle timers are avail-
able as optional accessories.
Defrost Controls
Electronic timed initiated, tempera-
ture 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 acces-
sory permits operation to 0° F.
Mechanical
Specifications
