508 01 1603 01
Specifications subject to change without notice.
27
Connecting Ductwork
Refer to the System Design Manual for the recommended
design and layout of ductwork. Fig. 18 shows recommend-
ed 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. 19. After flang-
es 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 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 4-11 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.
Fig. 18 — Typical Fan Discharge Connections for Multiple Fan Units
CAUTION
UNIT OPERATION HAZARD
Failure to follow this caution could cause equipment
damage.
Do not operate unit without ductwork or discharge ple-
num unless fan speed has been adjusted for external
static pressure of 0 in. wg. Failure to do so may result in
motor overload.
