Hook rigging shackles through holes in base rail, as shown in
Detail A. Holes in base rails are centered around the unit
center of gravity. Use wooden top skid, when rigging, to
_revent rigging straps from damaging unit.
Fig. 2 -- 48PG Rigging Label
Step 4 -- Field Fabricate Ductwork-- On vel_ical
units, secure all ducts to roof crab and building structure. Do not
connect dm_'ork to unit. For horizontal applications, field-
supplied flanges should be attached to horizontal dischtuge
openings and all ductwork secmed to the flanges. Insulate and
weatherproof all external ductwork, joints, and roof openings
with counter flashing and mastic in accor&mce with applicable
codes.
Ducts passing through an unconditioned space must be
insulated and covered with a vapor bturiel:
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.
Cabinet return-air static pressure (a negative condition) shall
not exceed 0.35 in. wg with economizer or 0.45 in. wg without
economizel:
These units are designed for a minimum continuous return-
air temperature in heating of 50 F (dry bulb), or an intermittent
operation down to 45 F (diy bulb), such as when used with a
night set-back thermostat.
To operate at lower return-air temperatures, a field-supplied
outdoor-air temperature control must be used to initiate both
stages of heat when the temperature is below 45 E Indoor com-
fort may be compromised when these lower air temperatures
are used with insufficient heating temperature rise.
Step 5 -- Make Unit Duct Connections
VERTICAL SUPPLY/RETURN CONFIGURATION -- Unit
is shipped in vertical supply/return configuration. Ductwork
openings are shown in Fig. 1and 3. Attach the ductwork to the
roof curb. Do not attach duct directly to the unit.
For venic_d supply and return units, tools or pans could
&op into ductwork and cause an injmy. 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.
HORIZONTAL SUPPLY/RETURN APPLICATIONS -- Unit
can be field-converted from vertical supply/return to horizontal
supply/return. Remove all screws securing horizontal duct
covers to duct panel. Save panels. Install duct covers in the
vertical duct openings in the basepan with the insulation side
up. Covel.s will drop into openings and can be secured using
field-supplied self-tapping screws. Ductwork can be attached
to duct flanges provided on unit. When securing ductwork to
unit, do not drill in area below bead or above top edge of duct
opening.
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