Step 5 - Field Fabricate Ductwork; Step 6 - Rig And Place Unit; Positioning On Curb - Carrier WeatherExpert 48LC 07 Series Installation Instructions Manual

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.
A minimum clearance is not required around ductwork.
CAUTION
PROPERTY DAMAGE HAZARD
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.
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
/ -in. square socket drive extension. For further details see
1
2
"Step 11 — Install External Condensate Trap and Line" on
page 15.
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.
Flue vent discharge must have a minimum horizontal clearance
of 4 ft (1220 mm) from electric and gas meters, gas regulators,
and gas relief equipment. Minimum distance between unit and
other electrically live parts is 48-in. (1220 mm).
Flue gas can deteriorate building materials. Orient unit such
that flue gas will not affect building materials.
Locate mechanical draft system flue assembly at least 48-in.
(1220 mm) from an adjacent building or combustible material.
NOTE: Installation of accessory flue discharge deflector kit will
reduce the minimum clearance to combustible material to 18-in.
(460 mm).
After the unit is in position remove all riggings, shipping mate-
rials and top skid. Recycle or dispose of all shipping materials.
9
CAUTION