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 twoTrane 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 withTrane 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-CycleTimer —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.
