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d. Compressors shall be protected from an over-- temperature and over-- amperage conditions by an internal,
motor overload device.
e. Compressor shall be factory mounted on rubber grommets.
f. Compressor motors shall have internal line break thermal and c urrent overload protection.
g. Crankcase heaters shall not be required for normal operating range.
23 81 19.13.L. Filter Section
1. Filters access is specified in the unit cabinet section of this specification.
2. Filters shall be held in place by a pivoting filter tray, facilitating easy removal and installation.
3. Shall consist of factory--installed, low velocity, throw--away 2-- in. thick fiberglass filters.
4. Filter face velocity shall not exceed 320 fpm at nominal airflows.
5. Filters shall be standard, commercially available sizes.
6. Only one size filter per unit is allowed.
23 81 19.13.M. Evaporator Fan and Motor
1. Evaporator fan motor:
a. Shall have permanently lubricated bearings
b. Shall have inherent automatic--reset thermal overload protection.
c. Shall have a maximum c ontinuous bhp rati ng 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 and 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. Shaft--up designs including those with “rain--slinger devices” shall not be
allowed.
2. Condenser Fans shall:
a. Shall be a direct--driven propeller type fan
b. Shall have aluminum blade s riveted to corrosion--resistant steel spiders and shall be dynamically balanc ed.
23 81 19.13.O. Special Features
1. Integrated Economizers:
a. Integrated, gear--driven parallel modulating blade design type capa ble of simult aneous economizer and
compressor operation.
b. Independent modules for vertical or horizontal return configurations shall be available . Vertical return
modules shall be ava ilable 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 a nd controls to provide free cooling with outdoor air when temperature and/or
humidity 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 temperature sensor shall be provided as standard. Outdoor air sensor set point shall be
adjustable and shall range from 40 to 100_F/4to38_C. Additional sensor opt ions shall be available as
accessories.
k. The economizer controller shall also provide control of an accessory power exhaust unit. function. Factory
set at 100%, with a ra nge of 0% to 100%.
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