Om
15780-2
PACKAGED ROOFTOP AIR HANDLING UNITS
3. York.
4. Or approved equal.
General: The operating range shall be between 115°F and 0 °F in cooling as standard
from the factory for units with microprocessor controls. Cooling performance shall
be rated in accordance with ARI testing procedures. All units shall be factory
assembled, internally wired, fully charged with R-410A, 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
for Central Cooling Air Conditioners.
Casing: Unit casing shall be constructed of zinc coated, heavy gauge, and galvanized
steel. Exterior surfaces shall be cleaned, phosphatized, and finished with a weather-
resistant baked enamel finish. Unit's surface shall be tested 672 hours in a salt spray
test in compliance with ASTM B117. Cabinet construction shall allow for all
maintenance on one side of the unit. All exposed vertical panels and top covers in the
indoor air section shall be insulated with a cleanable foil-faced, fire-retardant
permanent, odorless glass fiber 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 1.125 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.
Unit Top: The top cover shall be one piece construction or, where seams exist, it shall
be double-hemmed and gasket-sealed.
Filters: 2-inch thick, throwaway filters.
Compressors: All 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.
Refrigerant Circuits: 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 copper tubes mechanically bonded
to a configured aluminum plate fin. Coils shall be leak tested at the factory to ensure
the pressure integrity. The evaporator coil and condenser coil shall be leak tested to
650 psig and pressure tested to 450 psig. Removable, reversible, double-sloped
condensate drain pan with through the base condensate drain.
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: Indoor fan motor shall be belt drive type with FC fans with adjustable
sheaves. Motors shall be thermally protected.
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. A choice of microprocessor
or electromechanical controls shall be available. A centralized Microprocessor shall
13089K
