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Fig. 5 — Unit Leveling Tolerances
Install insulation, cant strips, roofing felt, and counter
flashing as shown. Ductwork must be attached to curb and
not to the unit. The accessory thru-the-base power and gas
connection package must be installed before the unit is set
on the roof curb. If field-installed thru-the-roof curb gas
connections are desired, use factory-supplied
coupling and gas plate assembly to mount the thru-the-roof
curb connection to the roof curb. Gas connections and pow-
er connections to the unit must be field-installed after the
unit is installed on the roof curb.
If electric and control wiring is to be routed through the
basepan, attach the accessory thru-the-base service connec-
tions to the basepan in accordance with the accessory instal-
lation instructions.
SLAB MOUNT (HORIZONTAL UNITS ONLY) —
Provide a level concrete slab that extends a minimum of 6 in.
(150 mm) beyond unit cabinet. Install a gravel apron in front of
condenser coil air inlet to prevent grass and foliage from
obstructing airflow.
NOTE: Horizontal units may be installed on a roof curb if
required.
ALTERNATE UNIT SUPPORT (IN LIEU OF CURB
OR SLAB MOUNT) — A non-combustible sleeper rail
can be used in the unit curb support area. If sleeper rails
cannot be used, support the long sides of the unit with a
minimum of 3 equally spaced 4-in. x 4-in. (102 mm x
102 mm) pads on each side.
Step 5 — Field Fabricate Ductwork —
turn-air static pressure (a negative condition) shall not ex-
ceed 0.35 in. wg (87 Pa) with economizer or 0.45 in. wg
(112 Pa) without economizer.
For vertical ducted applications, secure all ducts to roof
curb and building structure. Do not connect ductwork to
unit.
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
A-B
B-C
A-C
0.5 (13)
1.0 (25)
1.0 (25)
/
-in. pipe
1
2
Cabinet
re-
Fabricate supply ductwork so that the cross sectional di-
mensions are equal to or greater than the unit supply duct
opening dimensions for the first 18 in. (458 mm) of duct
length from the unit basepan.
Insulate and weatherproof all external ductwork, joints,
and roof openings with counter flashing and mastic in ac-
cordance with applicable codes.
Ducts passing through unconditioned spaces must be in-
sulated and covered with a vapor barrier.
If a plenum return is used on a vertical unit, the return
should be ducted through the roof deck to comply with ap-
plicable fire codes.
A minimum clearance is not required around ductwork.
Step 6 — Rig and Place Unit
Failure to follow this caution may result in damage to roof-
ing materials.
Membrane roofs can be cut by sharp sheet metal edges. Be
careful when placing any sheet metal parts on such roof.
Keep unit upright and do not drop. Spreader bars are re-
quired. Rollers may be used to move unit across a roof. Rig-
ging materials under unit (cardboard or wood) must be re-
moved PRIOR to placing the unit on the roof curb. Level by
using unit frame as a reference. See Table 2 and Fig. 6 for
additional information.
Lifting holes are provided in base rails as shown in
Fig. 6. Refer to rigging instructions on unit.
Rigging materials under unit (cardboard to prevent base
pan damage) must be removed PRIOR to placing the unit on
the roof curb
When using the standard side drain connection, ensure
the red plug in the alternate bottom connection is tight. Do
this before setting the unit in place. The red drain plug an be
tightened with a
1
/
-in. square socket drive extension. For
2
further details, see "Step 12 — Install External Condensate
Trap and Line" on page 14.
Before setting the unit onto the curb, recheck gasketing
on curb.
Failure to follow this caution may result in injury or equip-
ment damage.
All panels must be in place when rigging. Unit is not
designed for handling by fork truck when panels or pack-
aging are removed.
If using top crate as spreader bar, once unit is set, carefully
lower wooden crate off building roof top to ground. Ensure
that no people or obstructions are below prior to lowering
the crate.
9
CAUTION
CAUTION
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