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Specifications subject to change without notice.
FAS-FHS-072-180-01SI Rev. A
Fig. 16 — Unit Wiring
Connecting Ductwork
Figure 17 shows recommended duct connection to units
with 2 fans.
DISCHARGE CONNECTIONS
Duct flanges are factory-supplied; they are shipped inside
the unit attached to the hairpin end of the coil tube sheet for
field installation. Using the existing screws, install the duct
flanges on the unit’s fan deck. Each fan discharge requires
2 flanges; each flange must be bent in the middle to
conform to the discharge opening. (See Fig. 18.) After
flanges are installed, connect them to the supply duct using
a canvas connection to prevent vibration. It is important that
this connection be properly fabricated to prevent high air
friction losses and air noise.
RETURN CONNECTIONS
When using return-air ductwork, route return-air duct to the
unit’s return air inlet near the filter rack, using a canvas
connection to prevent transmission of unit vibration. If the
duct blocks off the unit’s access panel, provide a slip joint in
the ductwork to permit removal for servicing.
OUTDOOR-AIR INLET CONNECTIONS
Connect outdoor-air inlet to field-installed accessory econo
-
mizer. Refer to Economizer Installation Instructions.
Return-Air Filters
Type and size of filters are shown in Tables 1-4 and are
factory-supplied and factory-installed. In all units with 2 fans,
a filter replacement tool (hook) is shipped inside the unit for
field use when replacing filters. See the Service section on
page 24 for instructions on filter element replacement.
CAUTION
UNIT OPERATION HAZARD
Failure to follow this caution could cause equipment
damage.
Do not operate unit without ductwork or discharge
plenum unless fan speed has been adjusted for external
static pressure of zero in. wg. Failure to do so may result
in motor overload.