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A
B
Fig. 4 — Unit Leveling Tolerances
Install insulation, cant strips, roofing felt, and counter flash-
ing 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
assembly to mount the thru-the-roof curb connection to the
roof curb. Gas connections and power 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 connections
to the basepan in accordance with the accessory installation
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
Cabinet return-air static pressure (a negative condition)
shall not exceed 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.
Fabricate supply ductwork so that the cross sectional di-
mensions are equal to or greater than the unit supply duct open-
ing 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 accordance
with applicable codes.
Ducts passing through unconditioned spaces must be insu-
lated 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 applica-
ble fire codes.
A minimum clearance is not required around ductwork.
C
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
A-B
B-C
A-C
0.5 (13)
1.0 (25)
1.0 (25)
1
/
-in. pipe coupling and gas plate
2
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
required. Rollers may be used to move unit across a roof.
Rigging materials under unit (cardboard or wood) must be
removed PRIOR to placing the unit on the roof curb. Level by
using unit frame as a reference. See Table 2 and Fig. 5 for addi-
tional information.
Lifting holes are provided in base rails as shown in Fig. 5.
Refer to rigging instructions on unit.
Rigging materials under unit (cardboard or wood to prevent
basepan 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 be-
fore setting the unit in place. The red drain plug an be tightened
with a
1
/
-in. square socket drive extension. For further details,
2
see "Step 12 — Install External Condensate Trap and Line" on
page 15.
Before setting the unit onto the curb, recheck gasketing on
curb.
POSITIONING 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.
Position unit on roof curb so that the following clearances
are maintained:
/
in. (6.4 mm) clearance between the roof
1
4
curb and the base rail inside the front and rear, 0.0 in. clearance
between the roof curb and the base rail inside on the duct end
of the unit. This will result in the distance between the roof
curb and the base rail inside on the condenser end of the unit
being approximately
1
/
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
Failure to follow this caution may result in equipment
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.
Flue vent discharge must have a minimum horizontal clear-
ance of 4 ft (1220 mm) from electric and gas meters, gas regu-
lators, and gas relief equipment. Minimum distance between
unit and other electrically live parts is 48 inches (1220 mm).
9
CAUTION
CAUTION
in. (6.4 mm).
4
CAUTION
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