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JOHNSON CONTROLS
FORM 145.05-NOM1 (708)
Fan Start
Contact DO-5 on the Unit Control Board closes
whenever the Unit Control initiates constant volume
or VAV supply fan operation. This contact can be used
to identify supply fan operation. The connection point
for this feature is terminals 11 and 12 of the low voltage
terminal block.
VAV Box Full Open
Contact DO-4 on the Unit Control Board closes during
the unit start up mode and will remain closed until the
supply fan air proving switch closes. This contact can
be used to temporarily open the VAV boxes during start
up. The connection point for this feature is terminal 13
and 14 of the low voltage terminal block.
PHASE MONITOR
The unit can be ordered with a factory installed Phase
Monitor. The monitor checks the 3-phase power to the
unit for low voltage, single phasing, or phase reversal. If
a fault condition occurs the Phase Monitor interrupts the
24-volt power to the Unit Control. The Phase Monitor
will restore power to the Unit Control when the fault
condition is corrected.
DUCTING
Supply Air
For connection of supply ductwork directly to the
unit, a duct collar must be mounted at the unit outlet.
When connecting ductwork to the unit, a canvas type
connecting collar is recommended.
If a field fabricated plenum is used, canvas type
connectors are recommended at the duct connection to
the plenum.
Units are also available with a factory provided
discharge plenum. Supply duct connections to the
plenum opening(s) should include a canvas type
connector. Plenum opening sizes and locations will be
indicated on the job submittal drawing.
Return Air
Return air to the unit can be arranged in two ways.
Ducted Return
All ductwork connected to the unit should be of adequate
size and construction for the application. A canvas
type connector is also recommended where the duct
penetrates the machine room wall(s). This will prevent
vibration generated by air movement in the duct from
being transmitted out to the occupied spaces.
Failure to use the recommended duct
collars could result in noise transmis-
sion into the occupied space.
Do not obstruct unit access panel lo-
cated below the return opening.
Free Return
The mechanical equipment room may be used as a return
plenum with no hard connection at the unit.
Some building codes do not allow the
use of mechanical rooms as a return
plenum. Applicable local codes should
be checked for each installation.
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