—
9
—
III. STEP 3 — FIELD FABRICATE DUCTWORK
Secure all ducts to building structure. Use flexible duct con-
nectors between unit and ducts as required. Insulate and
weatherproof all external ductwork, joints, and roof openings
with counter flashing and mastic in accordance with applica-
ble codes.
Ducts passing through an unconditioned space must be insu-
lated and covered with a vapor barrier.
The 558F units with electric heat require a 1-in. clearance
for the first 24 in. of ductwork.
Outlet grilles must not lie directly below unit discharge.
NOTE: A 90-degree elbow must be provided in the ductwork
to comply with UL (Underwriters’ Laboratories) codes for
use with electric heat.
IV. STEP 4 — MAKE UNIT DUCT CONNECTIONS
Unit is shipped for through-the-bottom duct connections.
Ductwork openings are shown in Fig. 7. Field-fabricated con-
centric ductwork may be connected as shown in Fig. 8 and 9.
Attach all ductwork to roof curb and roof curb basepans.
Refer to installation instructions shipped with accessory roof
curb for more information.
V. STEP 5 — TRAP CONDENSATE DRAIN
See Fig. 4-6, and 10 for drain location. Plug is provided in
drain hole and must be removed when unit is operating. One
3
/
4
-in. half-coupling is provided inside unit evaporator sec-
tion for condensate drain connection. An 8
1
/
2
in. x
3
/
4
-in.
diameter nipple and a 2-in. x
3
/
4
-in. diameter pipe nipple are
coupled to standard
3
/
4
-in. diameter elbows to provide a
straight path down through holes in unit base rails (see
Fig. 11). A trap at least 4-in. deep must be used.
WARNING: For vertical supply and return units,
tools or parts could drop into ductwork and cause an
injury. Install a 90 degree turn in the return ductwork
between the unit and the conditioned space. If a
90 degree elbow cannot be installed, then a grille of
sufficient strength and density should be installed to
prevent objects from falling into the conditioned space.
Due to electric heater, supply duct will require
90 degree elbow.
NOTE:
Do not drill in this area; damage to basepan may result in water
leak.
Fig. 7 — Air Distribution — Thru-the-Bottom
NOTE:
Do not drill in this area; damage to basepan may result in water
leak.
Fig. 8 — Concentric Duct Air Distribution
3/4" FPT DRAIN
CONNECTION
1-3/8"
DRAIN HOLES
Shaded area indicates block-off panels.
NOTE:
Dimensions A, A
′,
and B, B
′
are obtained from field-supplied
ceiling diffuser.
Fig. 9 — Concentric Duct Details
Fig. 10 — Condensate Drain Details
(558F180,210 Shown)
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