Carrier WeatherExpert 50LC 07 Series Installation Instructions Manual page 9

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 dimen-
sions 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.
Minimum clearance is not required around ductwork.
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 OR OPTIONAL ELEC-
TRIC HEATERS
Horizontal applications require a minimum clearance to com-
bustible surfaces of 1-in. (25 mm) from duct for first 12-in.
(305 mm) away from unit. Vertical applications do not require
a minimum clearance.
Outlet grilles must not lie directly below unit discharge.
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 pre-
vent 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. 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. Re-
fer to rigging instructions on unit.
Rigging materials under unit (cardboard or wood) must be re-
moved 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 plug can be tightened with a
1 / -in. square socket drive extension. For further details, see
2
"Step 9 — Install External Condensate Trap and Line" on
page 12.
Before setting the unit onto the curb, recheck gasketing on
curb.
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 when packaging is 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.
POSITIONING ON CURB
Position unit on roof curb so that the following clearances are
maintained: 1 / -in. (6.4 mm) clearance between the roof curb
4
and the base rail inside the front and back, 0.0-in. clearance be-
tween 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 3 / -in. (84 mm).
5
16
Although unit is weatherproof, guard against water from higher
level runoff and overhangs.
After the unit is in position remove all shipping materials and
top skid, making sure to remove the wire ties which hold the
fan section to the top skid. Recycle or dispose of all shipping
materials.
9
CAUTION