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52 SSP-PRC002-EN
Mechanical
Specifications
Heat Pumps
General
Unit 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 (46°C) and 50°F
(10°C) in cooling as standard from
factory. Unit shall be UL 1995 listed and
rated in accordance with ARI Standard
340/360.
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 500 hours
in salt spray test. Unit shall have
removable end panels which allow
access to all major components and
controls.
Refrigeration System — Single
Compressor
TWA075A, TWA100A 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 unit
shall have both a liquid line and suction
gas line service valve with gauge port.
Unit 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, discharge line
thermostat, 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
TWA155B, TWA200B 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. Unit shall have
both a liquid line and suction gas line
service valve with gauge ports.
Unit 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, 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" (10mm) copper tubes
mechanically bonded to a configured
aluminum plate fin as standard. Coil
shall be factory pressure and leak tested
to 420 psig (2,930 kPa) 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 (660 or 711 mm)
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 shall be
included. Timed override limits defrost
cycle to 10 minutes.
Low Ambient Operation
Standard units shall start and operate to
approximately 50°F (10°C) when
matched with Trane air handlers and
coils. Optional head pressure control
accessory permits operation to 0°F
(-17.8°C).
ACCESSORIES
Low Ambient Head Pressure Control —
This accessory 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 (-17.8°C).
Vibration Isolation Packages — This
accessory shall reduce transmission of
noise and vibration to building
structures, equipment, and adjacent
spaces. Packages shall be available in
either neoprene-in-shear or spring-flex
types.
Time Delay Relay — This accessory
shall prevent compressors in dual
compressor unit from coming on line
simultaneously. Timer shall be 24-volt,
60 cycle, with four minute timing
period.
Anti-Short-Cycle Timer — This
accessory shall prevent rapid on-off
compressor cycling in light load
conditions by not allowing compressor
to operate for 5-7 minutes upon
shutdown. This accessory shall consist
of a 24-volt, 60 cycle, solid state timing
device with either 5 or 7 minute fixed-
off timing period.