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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 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
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
!
PROPERTY DAMAGE HAZARD
Failure to follow this caution may result in damage
to roofing materials.
Membrane roofs can be cut by sharp sheet metal
edges. Be careful when placing any sheet metal parts
on such roof.
For Units with Accessory Electric Heaters —
All installations require a minimum clearance to
combustible surfaces 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.
WARNING
!
PERSONAL INJURY HAZARD
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 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.
Step 6 — Rig and Place Unit
Keep unit upright and do not drop. Spreader bars are not
required if top crating is left on unit. Rollers may be used to
move unit across a roof. Level by using unit frame as a
reference. See Table 4 and Fig. 9 for additional information.
Lifting holes are provided in base rails as shown in Fig. 9.
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 pan
plug can be tightened with a
extension. For further details see Step 9 − Install External
Condensate Trap and Line on page 16.
Before setting the unit onto the curb, recheck gasketing on
curb.
CAUTION
!
UNIT DAMAGE HAZARD
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.
Positioning on Curb —
Position unit on roof curb so that the following clearances
1
are maintained:
/
in. (6.4 mm) clearance between the
4
roof 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
mm).
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
For size 08 and 09 units: 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 tubing,
wiring, or controls. Remove the strapping and replace the
access panel.
Remove all shipping materials and top skid. Recycle or
dispose of all shipping materials.
13
1
/
−in. square socket drive
2
1
/
in. (6.4
4
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