2.7.2.7
Unit Controls
The evaporative condenser unit shall be provided with modulating capacity
control dampers mounted in the discharge of the fan housing. On a decrease
in refrigerant discharge pressure the dampers shall modulate to reduce the
airflow through the evaporative condenser. Controls shall include a
proportional acting pressure controller, a control transformer, motor
actuator with linkages and end switches to cycle fan motor on and off.
Cycling of a fan motor on and off shall be in accordance with the
manufacturer.
2.7.3
Compressor
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NOTE: Delete this paragraph if only a remote
condenser is required.
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Unit shall be rated in accordance with ARI 500. Compressor shall be direct
drive, semi-hermetic or hermetic reciprocating, or scroll type capable of
operating at partial load conditions. Compressor shall be capable of
continuous operation down to the lowest step of unloading as specified.
Units 35 kW 120,000 Btuh and larger shall be provided with capacity
reduction devices to produce automatic capacity reduction of at least 50
percent. If standard with the manufacturer, two or more compressors may be
used in lieu of a single compressor with unloading capabilities, in which
case the compressors will operate in sequence, and each compressor shall
have an independent refrigeration circuit through the condenser and
evaporator. Each compressor shall start in the unloaded position. Each
compressor shall be provided with vibration isolators, crankcase heater,
[lubrication pump,] thermal overloads, and [high] [high and low] pressure
safety cutoffs and protection against short cycling.
2.8
AIR-CONDITIONERS FOR ELECTRONIC DATA PROCESSING (EDP) SPACES
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NOTE: Indoor units are inherently noisy. In noise
sensitive areas, steps should be taken to attenuate
sound.
Air-cooled and water-cooled air-conditioning units
with capacities less than 39.5 kW (135,000 Btuh)
will be rated in accordance with ARI 210/240.
Air-cooled, water-cooled, and evaporatively-cooled
air-conditioning units with capacities greater than
or equal to 39.5 kW (135,000 Btuh) will be rated in
accordance with ARI 340/360.
Delete the last sentence if an integral water-cooled
condenser or a packaged air-cooled unit is specified.
Inapplicable equipment and system requirements will
be deleted or modified in all paragraphs to suit the
system designed. Coordinate the standard and design
option features typical for each
Air-Conditioner/Heat Pump unit and individual
installation. Care must be taken to avoid
specifying design options which are generally
SECTION 15700A
Page 27
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