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Fig. 6 — Unit Leveling Tolerances
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 dimensions
are equal to or greater than the unit supply duct opening dimen-
sions 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 ap-
plicable codes.
Ducts passing through unconditioned spaces must be insulated
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 applicable fire codes.
CAUTION
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.
UNITS WITH ACCESSORY ELECTRIC HEATERS
All installations require a minimum clearance to combustible sur-
faces of 1 in. (25 mm) from duct for first 12 in. (305 mm) away
from unit.
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) code for use with
electric heat.
C
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
B
A-B
B-C
0.5 (13)
1.0 (25)
1.0 (25)
Failure to follow this warning could cause personal injury.
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 condi-
tioned 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.
Step 6 — Rig and Place Unit
Keep unit upright and do not drop. Spreader bars are required.
Rollers may be used to move unit across a roof. Rigging materials
A-C
under unit (cardboard or wood) must be removed PRIOR to plac-
ing the unit on the roof curb. Level by using unit frame as a refer-
ence. See Table 2 on page 9 and Fig. 7 for additional information.
Lifting holes are provided in base rails as shown in Fig. 7. Refer to
rigging instructions on unit.
Before setting the unit onto the curb, recheck gasketing on curb.
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.
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:
1
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
(6.4 mm).
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.
After unit is in position, remove the compressor access panel.
Holding the blocking between compressors with one hand, cut the
strapping. Carefully remove the blocking without damaging tub-
ing, wiring, or controls. Remove the strapping and replace the ac-
cess panel.
After unit is in position, remove rigging skids and shipping mate-
rials.
11
WARNING
CAUTION
/
in. (6.4 mm) clearance between the roof curb and
4
CAUTION
/
in.
1
4
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