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c. Shall have a maximum continuous bhp rating for continuous duty operation; no safety factors above that rating
shall be required.
2. Belt--driven Evaporator Fan:
a. Belt drive shall include an adjustable pitch motor pulley.
b. Shall use sealed, permanently lubricated ball --bearing type.
c. Blower fan shall be double--inlet type with forward--curved blades.
d. Shall be constructed from steel with a corrosion resistant finish a nd dynamically balanced.
23 81 19.13.N. Condenser Fans and Motors
1. Condenser fan motors:
a. Shall be a totally enclosed motor.
b. Shall use permanently lubricated bearings.
c. Shall have inherent thermal overload protection with an automatic reset feature.
d. Shall use a shaft--down design on 04 to 12 models and shaft--up on 14 size with rain shield.
2. Condenser Fans:
a. Shall be a direct--driven propeller type fan.
b. Shall have aluminum blades riveted to corrosion--resistant steel spiders and shall be dynamically balanced.
23 81 19.13.O. Special Features Options and Accessories
1. Integrated Economizers:
a. Integrated, gear--driven parallel modulating blade design type capabl e of simultane ous economizer and com-
pressor operation.
b. Independent modules for vertical or horizontal return configurations shall be available. Vertical return modules
shall be available as a factory installed option.
c. Damper blades shall be galvanized steel with composite gears. Plastic or composite blades on intake or return
shall not be acceptable.
d. Shall include all hardware and controls to provide free cooling with outdoor air when temperat ure and/or hu-
midity are below setpoints.
e. Shall be equipped with gear driven dampers for both the outdoor ventilation air and the return air for positive
air stream control.
f. Shall be equipped with low--leakage dampers, not to exceed 2% leakage at 1 in. wg pressure differential.
g. Shall be capable of introducing up to 100% outdoor air.
h. Shall be equipped with a barometric relief damper capable of relieving up to 100% return air.
i. Shall be designed to close damper(s) during loss-- of --power situations with spring return built into motor.
j. Dry bulb outdoor air tempe rature se nsor shall be provided as standard. Outdoor air sensor setpoint shall be
adjustable and shall range from 40 to 100_F/4to38_C. Additional sensor options shall be available as ac-
cessories.
k. The economizer controller shall also provide control of an accessory power exhaust unit function. Factory set
at 100%, with a range of 0% to 100%.
l. The economizer shall maintain minimum airflow i nto the building during occupied period and provide design
ventilation rate for full occupancy. A remote potentiometer may be used to override the damper setpoint.
m. Dampers shall be completel y closed when the uni t is in the unoccupied mode.
n. Economizer controller shall accept a 2--10 Vdc CO
2
sensor input for IAQ/DCV control. In this mode , dampers
shall modulate the outdoor air damper to provide ventilation based on the sensor input.
o. Compressor lockout sensor shall open at 35_F(2_C) and close closes at 50_F(10_C).
p. Actuator shall be direct coupled to economizer gear. No linkage arms or control rods shall be acceptable.
q. Economizer controller shall provide indications when in free cooling mode, in the DCV mode, or the exhaust
fan contact is closed.
2. Two--Position Damper
a. Damper shall be a Two--Position Damper. Damper travel shall be from the full closed position to the field ad-
justable %--open setpoint.
b. Damper shall include adjustable damper travel from 25% to 100% (full open).
c. Dampe r shall include single or dual blade, gear driven dampers and actuator motor.
d. Actuator shall be direct coupled to damper gear. No linkage arms or control rods shall be acceptable.
e. Dampe r will admit up to 100% outdoor air for applicabl e rooftop units.
f. Damper shall close upon indoor (evaporator) fan shut off and/or loss of power.
g. The damper actuator shall plug i nto the rooftop unit’s wiring harness plug. No hard wiring shall be required.
h. Outside air hood shall include aluminum water entrainment filter.
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