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PACKAGED AIR CONDITIONING UNITS Section 15855 15-1207 3. The coils shall be non-ferrous construction with aluminum fins mechanically bonded to durable copper tubes. Coils shall be leak tested under water with minimum 200 psi air at the factory prior to installation in the units. 4. The compressor shall be resiliently mounted and have built- in, three -mode crankshaft lubrication; crankcase heater; discharge temperature limiter; and current- and temperature - sensing motor overloads. 5. The cooling system shall be protected by high and low pressure switches, filter dryer, oil failure switch, and a five-minute, compressor, timed off cycle controller (anti- recycle timer), and evaporator coil frostat that shall disable cooling when temperatures on the evaporator coil reach 10 degrees or below. Mechanical cooling will start again when temperatures on the evaporator coil rise to 50 degrees or above. B. Cabinet: 1. Unit cabinet shall be constructed of phosphated, zinc --coated, pre --painted steel capable of with standing 500 hours in salt spray. 2. Normal service shall be through multiple removable cabinet panels. 3. The unit shall be constructed on a rust proof unit base that has an externally trapped, integrated sloped drain. 4. Evaporator fan compartment top surface shall be insulated with a minimum '/2 inch thick, 1 '/2" density, flexible fiberglass insulation bonded with a phenolic binder, neoprene coated on the air side. 5. Gas heat compartment shall be insulated with aluminum foil -faced fiberglass insulation. C. Service Access: 1. All components, wiring, and inspection areas shall be completely accessible through removable access panels. 2. Hinged access panels shall be provided at access to filter section, fan section, compressor section, heat section, and controls. D. Supply Air Blowers: 1. The evaporator fan motor shall be a multi -speed, belt -drive, as shown on equipment drawings. 2. Supply air blower to be controlled via a factory installed variable frequency drive. 3. Fan wheel shall be made from steel, be double -inlet type with forward curved blades with corrosion resistant finish. 4. Fan wheel shall be dynamically balanced. 5. Supply blower motors shall be thermally protected and meet the US EPACT 1992 Code. 6. Supply blower motors to be high efficiency option. E. Condenser Fans: 1. Condenser fan shall be direct drive propeller type with aluminum blades riveted to corrosion resistant steel spiders, be dynamically balanced, and discharge air vertically. F. Condenser Coil Guard: 1. Factory installed guard shall be manufactured from minimum 18 gauge expanded steel. 2. The guards shall be powder coated to match the unit color. 3. Guard open area shall be between fifty percent and sixty percent. G. Base unit controls: 1. Unit to be provided with base electromechanical controls. 5