Signature Series Self-
Contained Units
Cabinet
The unit framework shall be formed structural steel members of 14-gauge galvanized steel. Exterior panels shall be fabricated from 18-gauge galvanized steel. The fan and compressor sections shall be insulated with ¾-inch (19 mm) of
1.75lb./cu. ft. (28 kg./cu. ft.) density fiberglass insulation.
The unit shall be provided with removable panels to allow service access to compressors, condensers, fan motor, fan bearings, coils, and valves. Removable panels shall be secured with quick-acting fasteners. The refrigerant sight glasses shall be accessible during operation. The control panel door shall have lift-off hinges.
Compressors
Units shall have multiple compressors with independent circuits for water-cooled units and manifolded circuits for air- cooled units. Compressors shall be manufactured by the unit manufacturer. Scroll compressors shall be heavy duty suction cooled type with suction screen, centrifugal oil pump with dirt separator, oil charging valve, and oil sight glass. Protective devices for low pressure, high pressure, and motor temperature shall be provided. The compressors shall be mounted on isolators for vibration isolation.
Condenser (SCWF/SIWF only)
One condenser shall be provided for each compressor.The condensers shall be shell-and-tube design with removable heads and mechanically cleanable tubes. Tubes shall be ¾-inch (19mm) OD and constructed of copper. Condenser waterside working pressure shall be 400 psig. All condenser water piping including, cleanouts, shall be factory installed to provide single connections for water inlet and outlet.
Evaporator
The evaporator coil shall be seamless copper tubes expanded into aluminum fins.Tubes shall be ½-inch (13mm) OD with internally enhanced surfaces. Coil shall have staggered tube arrangement
with intertwined circuiting and no more than 12 fins per inch.
The drain pan shall be positively sloped in all directions to ensure proper condensate removal. The drain pan shall be fabricated of galvanized steel and insulated with ¾- inch (19 mm) of 1-lb. (0.5 kg) density fiberglass. Drain piping, including a trap with cleanout, shall be provided with a single-point connection to the unit’s exterior.
Refrigerant Circuit (SCWF only) Refrigerant circuits shall be independent and completely piped including sight glasses, distributors, thermal expansion valves with adjustable superheat and external equalizer, and high pressure relief valves with ½-inch (13 mm) flare connection. Filter driers ship loose for field installation. Unit shall be provided with adequate means of frost control.The circuits shall be factory dehydrated, charged with oil and refrigerant 22. Compressors shall be mounted on rubber-in-shear isolators for vibration isolation.
Refrigerant Circuit (SCRF/SIRF only) Two refrigerant circuits shall be piped to the unit’s exterior.The refrigerant piping includes filter driers (for field installation), sight glasses, distributors, thermal expansion valves with adjustable superheat and external equalizer. Unit shall be provided with adequate means of frost control. The circuits shall be factory tested, dehydrated and then charged with dry nitrogen. Compressors shall be mounted on rubber-in-shear isolators for vibration isolation.
Supply Fan
The supply fan shall be a single forward curved medium pressure fan secured to a solid steel shaft with grease lubricated bearings designed for 200,000 hours. Both fan bearings shall have greaselines extended to a common location. The drive components shall include fixed pitch sheaves and multiple V-belt sized for 130% nominal motor horsepower.The supply fan motor shall have a service factor of 1.15. The supply fan motor shall be either:
•Standard efficiency open drip-proof
•Premium efficiency open drip-proof
•Totally enclosed fan cooled standard
efficiency.
Supply fan motor shall have a standardT- frame. All drive components shall be accessible without using scaffolds or ladders.
The entire fan assembly, including drive components, shall be mounted on a common base. The fan base shall be isolated inside the unit. The entire assembly shall be statically and dynamically balanced at the factory.
Filters
Two-inch (51 mm) throwaway fiberglass filters shall be provided for installation during construction.
Unit Controls - DDC
Microprocessor controls shall be provided to control all unit functions. The control system shall be suitable to control CV or VAV applications.The controls shall be factory-installed and mounted in the main control panel. All factory-installed controls shall be fully commissioned (run tested) at the factory.The unit shall have a human interface panel with 16-key keypad, a two line, 40 character clear language (English, French, or Spanish) display as standard to provide the operator with full adjustment and display of control data functions. The unit controls shall be used as a stand-alone controller or as part of a building management system involving multiple units.
The unit shall be equipped with a complete microprocessor control system. This system shall consist of temperature and pressure (thermistor and static pressure transducer) sensors, printed circuit boards (modules) and a unit mounted human interface panel. Modules (boards) shall be individually replaceable for service ease. All microprocessors, boards, and sensors shall be factory mounted, wired, and tested.
The microprocessor boards shall be stand-alone DDC controls not dependent on communications with an on-site PC or building management network. The microprocessors shall be equipped with on-board diagnostics, indicating that all hardware, software, and interconnecting wiring are in proper operating condition. The modules (boards) shall be protected to prevent RFI and voltage transients from affecting the board’s circuits. All field
