system shall be based on sensing of actual condensing pressure in
conjunction with manufacturer's method of fan or damper control or by
flooding the condenser. [Multifan units with power operated fan discharge
dampers, shall include gravity dampers.] [Electric damper operator torque
shall be at least 2.0 times required torque.] [Air volume control is not
acceptable for ambient conditions below 2 degrees C 35 degrees F.]
Controls shall be set to produce a minimum 21 degrees C 70 degrees F
saturated refrigerant condensing temperature.
2.3.9
Control Panels
Unit mounted control panels shall be housed in NEMA ICS 6, Type 1 or 3A
enclosures. Controls shall include [control transformer,] [fan motor
[contactor] [starters],] [solid-state speed control,] overload protective
devices, interface with local and remote components, miscellaneous electric
devices, and intercomponent wiring to terminal block points.
2.4
CONDENSERS, WATER-COOLED
Condenser shall be [remote mounted] [and] [integral to water-cooled
condensing unit] and shall conform to ARI 450.
2.4.1
Capacity Criteria
Ratings shall be in Btuh heat rejection for ARI 450 Group [1] [3]
conditions, and for application at indicated design conditions. Ratings
shall be based on [0.0005] [0.001] cooling water side fouling factor at
design velocity. Coolant side pressure drop at design condition flow and
fouling factor shall not exceed that indicated and shall be based on
tube-side velocities of not less than 1.07 nor greater than 2.44 m/s 3.5
nor greater than 8 fps. When condenser is used for refrigerant storage
during pumpdown, system charge shall be held within 80 percent of unit
volume and storage capacity shall be stated. [Condensers shall be designed
for coolant side working pressure of not less than [690] [1034] kPa (gage)
[100] [150] psig, refrigerant side working pressure of not less than 2068
kPa (gage) 300 psig.] A portion of entering coolant shall be in heat
transfer contact with liquid refrigerant to provide [_____] degrees C
degrees F subcooling.
2.4.2
Shell and Tube Type
Condensers shall be of the shell and tube type with the coolant in the
tubes. The design pressure drop shall govern the number of passes.
Condenser heads shall have pipe connections which permit access to or
removal of the tubes. Materials of construction shall be suitable for the
service in which used. Condensers shall conform to ARI 450, with safety
provisions conforming to ASHRAE 15. Where coolant may be subject to
freezing, condensers shall be gravity drainable and shall be fitted with
automatic drain and vent valves.
2.4.3
Coolant Control
Control valves shall be [automatic, self-contained, controlled by
condensing pressure, and shall close bubble-tight when compressor is not
operating.] [modulating three-way mixing type, controlled by pressure
controller.] [Atmospheric cooling equipment shall be deenergized at
indicated set point.] Control shall be set for a saturated refrigerant
condensing temperature of 21 degrees C 70 degrees F.
SECTION 15602N
Page 15
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