General
The units shall be convertible airflow.The operating range shall be between 115°F and 0°F in cooling as standard from the factory for units with microprocessor controls. Operating range for units with electromechanical controls shall be between 115°F and 40°F. Cooling performance shall be rated in accordance with ARI testing procedures. All units shall be factory assembled, internally wired, fully charged with R-22, and 100 percent run tested to check cooling operation, fan and blower rotation, and control sequence before leaving the factory. Wiring internal to the unit shall be colored and numbered for simplified identification. Units shall be UL listed and labeled, classified in accordance to UL 1995/CAN/CSA No. 236-M90 for Central Cooling Air Conditioners. Canadian units shall be CSA Certified.
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 1000 hours in a salt spray test in compliance with ASTM B117. Cabinet construction shall allow for all maintenance on one side of the unit. Service panels shall have lifting handles and be removed and reinstalled by removing only a single fastener while providing a water and air tight seal. All exposed vertical panels and top covers in the indoor air section shall be insulated with a cleanable foil-faced, fire-retardent permanent, odorless glass fiber material. The base of the unit shall be insulated with 1/2 inch, 1 pound density foil-faced, closed-cell material. All insulation edges shall be either captured or sealed.The unit’s base pan shall have no penetrations within the perimeter of the curb other than the raised 11/8 inch high downflow supply/return openings to provide an added water integrity precaution, if the condensate drain backs up.The base of the unit shall have provisions for forklift and crane lifting, with forklift capabilities on three sides of the unit.
UnitTop
The top cover shall be one piece construction or where seams exist, it shall be double-hemmed and gasket- sealed. The ribbed top adds extra strength and prevents water from pooling on unit top.
Filters
One inch, throwaway filters shall be standard on all 3-5 ton units.The filter rack can be converted to two inch capability. Two inch filters shall be factory supplied on all 6-10 ton units. Optional 2-inch pleated filters shall be available.
Compressors
All 3 ton standard units shall have direct- drive, hermetic, reciprocating type compressors.The reciprocating type compressors have a 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 unit nameplate voltage. Crankcase heater, internal temperature, and current- sensitive motor overloads shall be included for maximum protection. Compressors shall have internal spring isolation and sound muffling to minimize vibration transmission and noise. Low pressure switches shall be standard.
3 ton high efficiency and 4-10 ton standard and high efficiency units shall have direct-drive, hermetic, scroll type compressors with centrifugal type oil pumps. Motor shall be suction gas-cooled and shall have a voltage utilization range of plus or minus 10 percent of unit nameplate voltage. Internal overloads shall be provided with the scroll compressors. Crankcase heaters shall be included on 7½ ton standard efficiency units.
Refrigerant Circuits
Each refrigerant circuit offers a choice of independent fixed orifice expansion devices or thermal expansion valve. Service pressure ports, and refrigerant line filter driers are factory-installed as standard. An area shall be provided for replacement suction line driers.
Evaporator and Condenser Coils Internally finned, 5/16” copper tubes mechanically bonded to a configured aluminum plate fin shall be standard. Coils shall be leak tested at the factory to ensure the pressure integrity.The evaporator coil and condenser coil shall be leak tested to 200 psig and pressure tested to 450 psig.The condenser coil shall have a patent pending 1+1+1 hybrid coil designed with slight gaps for ease of cleaning. A removeable, reversible, double-sloped condensate drain pan with provision for through the base condensate drain is standard.
Outdoor Fans
The outdoor fan shall be direct-drive, statically and dynamically balanced, draw-through in the vertical discharge position.The fan motor shall be permanently lubricated and shall have built-in thermal overload protection.
Indoor Fan
All 3-5 ton 3-phase units offer a choice of direct-drive, FC, centrifugal fans or belt driven, FC centrifugal fans with adjustable motor sheaves. 3-5 ton direct drive oversized motors shall be available for high static operations. All 6-10 ton units shall have belt drive motors with an adjustable idler-arm assembly for quick- adjustment to fan belts and motor sheaves. All motors shall be thermally protected. All indoor fan motors meet the U.S. Energy Policy Act of 1992 (EPACT).
Controls
Unit shall be completely factory-wired with necessary controls and contactor pressure lugs or terminal block for power wiring. Unit shall provide an external location for mounting a fused disconnect device. Microprocessor controls provide for all 24 volt control functions.The resident control algorithms shall make all heating, cooling, and/or ventilating decisions in response to electronic signals from sensors measuring indoor and outdoor temperatures.The control algorithm maintains accurate temperature control, minimizes drift from set point, and provides better building comfort. A centralized Microprocessor shall provide anti-short cycle timing and time delay between compressors to provide a higher level of machine protection.
