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Fig. 23 — ACH550 VFD Location for the following units: FAS300-336 (575V only)
Connecting Ductwork
Figure 24 shows recommended duct connection to units
with 2 fans.
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 0 in. wg. Failure to do so may result in
motor overload.
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 con-
form to the discharge opening. (See Fig. 25.) After flanges
are installed, connect them to the supply duct using a can-
vas connection to prevent vibration. It is important that this
connection be properly fabricated to prevent high air friction
losses and air noise.
FAS-FHS-240-336-02SI
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 con-
nection 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 for
instructions on filter element replacement.
Specifications subject to change without notice.
Variable
Frequency
Drive (VFD)
25
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