Dampers shall be controlled in unison by single or dual actuators.
Actuator shall be as specified in paragraph CONTROLS. Unit shall control
delivered air volumes within plus or minus 5 percent with inlet air
variations from 250 to 2000 Pa 1 to 8 inch water gauge in either duct.
Mixing baffles shall be included with the unit casing. Cabinet and closed
duct leakage shall not exceed 2 percent of maximum rated air volume.
Internal resistance of units shall not exceed [_____] Pa inch water gauge
at maximum flow range.
2.9.3.5
Ceiling Induction Terminal Units
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NOTE: Do not use ceiling induction units on NAVFAC
projects.
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Provide ceiling induction unit with a calibrated primary air volume sensing
device, primary air valve, induced air damper, and insulated induction
tube. Arrange unit to induce air from the ceiling plenum to maintain a
maximum total flow circulated to the conditioned space. Primary air shall
be varied upon demand of the room thermostat. Upon a demand for maximum
cooling, the unit shall deliver 100 percent primary air and, at minimum
cooling, shall deliver [50] [25] percent primary air. Terminal unit shall
be capable of closing to full shut off without additional actuators or
linkage changes. Terminals shall reset primary air volume within plus or
minus 5 percent determined by the thermostat regardless of upstream changes
in the static pressure. Minimum inlet static pressure shall not exceed 250
Pa 1 inch water gauge, including a maximum of 75 Pa 0.3 inch water gauge
downstream static pressure. External differential pressure taps separate
from control pressure taps shall be provided for primary air flow
measurement with 0 to 250 Pa 0 to 1 inch water gauge range. Each unit
shall be normally [open] [closed] upon loss of pneumatic pressure.
Actuator and accuracy controls shall be completely factory piped requiring
only field installation of 138 kPa 20 psi pneumatic main air and room
thermostat.
2.9.3.6
Series Fan Powered Variable Air Volume (VAV) Terminals
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NOTE: For evaporator variable airflow applications
such as VAV or multizone, provisions for capacity
control and minimum capacity must be indicated.
Capacity control may be compressor unloading or
multiple compressors. For minimum capacity control,
these applications should be provided with factory
installed hot-gas bypass.
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Provide units factory assembled, designed, tested, and rated in accordance
with ARI 880. Units shall be ARI certified and listed in the ARI APD.
Units shall provide a supply air discharge mix by modulation of conditioned
primary air and recirculating of return air. Units shall include casing,
centrifugal fan and motor, primary VAV damper or valve, electronic volume
regulator, discharge air damper, primary air inlet cone with high and low
pressure flow sensors, recirculating air filter frames, filter, and
electrical disconnect. [Provide hot water heating coils integral to the
terminal, or provide insulated hot water coil section attached to the
discharge of the terminal.]
SECTION 15895
Page 47
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