Slab Mount (Horizontal Units Only); Alternate Unit Support (In Lieu Of Curb Or Slab Mount); Step 5 - Field Fabricate Ductwork; Step 6 - Rig And Place Unit - Carrier WeatherExpert 48LC Installation Instructions Manual

Curb should be level. This is necessary for unit drain to
function properly. Unit leveling tolerances are shown in
Fig. 5. Refer to Accessory Roof Curb Installation
Instructions for additional information as required.
Fig. 5 - - Unit Leveling Tolerances
Install insulation, cant strips, roofing felt, and counter
flashing as shown. Ductwork must be attached to curb and
not to the unit. The accessory thru- - the- - base power and
gas connection package must be installed before the unit
is set on the roof curb. If field- - installed thru- - the- - roof
curb gas connections are desired, use factory- - supplied
1
/ - - in. pipe coupling and gas plate assembly to mount the
2
thru- - the- - roof curb connection to the roof curb. Gas
connections and power connections to the unit must be
field- - installed after the unit is installed on the roof curb.
If electric and control wiring is to be routed through the
basepan, attach the accessory thru- - the- - base service
connections to the basepan in accordance with the
accessory installation instructions.
Slab Mount (Horizontal Units Only) —
Provide a level concrete slab that extends a minimum of
6 in. (150 mm) beyond unit cabinet. Install a gravel apron
in front of condenser coil air inlet to prevent grass and
foliage from obstructing airflow.
NOTE: Horizontal units may be installed on a roof curb
if required.
Alternate Unit Support
(In Lieu of Curb or Slab Mount) —
A non- - combustible sleeper rail can be used in the unit curb
support area. If sleeper rails cannot be used, support the long
sides of the unit with a minimum of 3 equally spaced 4- - in. x
4- - in. (102 mm x 102 mm) pads on each side.
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.
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
A-B B-C A-C
0.5" (13) 1.0" (25) 1.0" (25)
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.
!
PROPERTY DAMAGE HAZARD
C06110
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.
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 1 and
Fig. 6 for additional information.
Lifting holes are provided in base rails as shown in Fig. 6.
Refer to rigging instructions on unit.
Rigging materials under unit (cardboard or wood) 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 plug can be
tightened with a
further details see Step 11 — Install External Condensate
Trap and Line on page 16.
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.
10
CAUTION
1
/ - - in. square socket drive extension. For
2
CAUTION