5566217-JIM-C-1019
Johnson Controls Ducted Systems 35
Smoke detectors
The factory-installed smoke detector shuts down operation of
the unit by interrupting power to the UCB when smoke is
detected within its mounting compartment. The smoke detector
option is available for both supply and return air configurations.
Be aware that the supply air configuration has the sensor com-
ponent mounted in the blower section with its control module
mounted in the return air compartment.
You must test and maintain the detector on a regular basis
according to NFPA 72 requirements. You must clean the
detector at least once a year. For specific troubleshooting and
maintenance procedures, refer to the smoke detector's
installation instructions that accompany the unit.
Motorized outdoor damper
The motorized outdoor damper can be a factory-installed option
or a field-installed accessory. If factory installed, refer to the
instructions included with the outdoor air hood to complete the
assembly. Field-installed motorized outdoor damper
accessories include complete instructions for installation.
Economizer
The economizer can be a factory-installed option or a field-
installed accessory. If factory installed, refer to the instructions
included with the economizer to complete the assembly. Field-
installed economizer accessories include complete instructions
for installation.
There are two economizer options:
1. Down flow application with barometric relief hood standard.
2. Horizontal flow application that requires the purchase of a
barometric relief hood.
Power exhaust
The power exhaust can be a factory installed-option or a field-
installed accessory. If factory installed, refer to the instructions
included with the power exhaust to complete the assembly.
Field-installed power exhaust accessories include complete
instructions for installation.
The power exhaust factory-installed option is for down flow
application only.
There are two field-installed power exhaust accessories:
1. Down flow application.
2. Horizontal flow application that requires the purchase of a
barometric relief hood.
Rain hood
For factory-installed options, all of the hood components,
including the filters, the gasketing, and the hardware for
assembling, are packaged and located between the condenser
coil section and the main unit cabinet. For field-installed
accessories, all parts necessary for the installation come in the
accessory kit.
Optional variable air volume
A variable air volume (VAV) option using a variable frequency
drive (VFD) is available for applications that require a constant
supply-duct static pressure. A differential pressure transducer is
used to monitor supply duct static pressure and return a speed
reference signal to the VFD to control the output of the indoor
blower motor.
Duct static pressure transducer
A 0-5 in. WC pressure transducer, located in the control box
compartment, is used to sense static (gauge) pressure in the
supply air duct and convert this pressure measurement to a
proportional 0-5 VDC electrical output. Pressure-transmitting
plastic tubing (1/4 in. diameter) must be field supplied and
installed from the transducer to both the ductwork and to the
atmosphere.
Connect the tubing from the HIGH pressure tap of the
transducer to a static pressure tap (field supplied) in the supply
duct located at a point where constant pressure is expected. To
The use of duct smoke detectors have specific limitations
as established by the National Fire Protection
Association. Note that duct smoke detectors are not a
substitute for other fire detection systems, including the
following.
• An open area smoke detector
• Early warning detection
• A building's regular fire detection system.
Refer to NFPA Code 72 and Standard 90A for additional
information.
Factory-installed smoke detectors may be subjected to
extreme temperatures during off times due to outside air
infiltration. These smoke detectors have an operational
limit of -4°F to 158°F. To prevent false alarms, you must
relocate smoke detectors installed in areas that could be
outside this range.
To ensure that adequate airflow reaches the smoke
detector's sensor, make sure that the holes of the
sampling tube face into the air stream, and that the far-
end of the sampling tube is sealed with the plastic end
cap.
The unit's supply airflow must be adjusted to provide a
pressure differential across the smoke detector's
sampling and exhaust ports of at least 0.01 inches of
water and no more than 1.11 inches of water, as
measured by a manometer.
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