Alternate Unit Support (In Lieu Of Curb Or Slab Mount); Step 5 - Field Fabricate Ductwork; Units With Accessory Or Optional; Step 6 - Rig And Place Unit - Carrier WeatherMaster Series Installation Instructions Manual

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 di-
mensions 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 accor-
dance with applicable codes.
Ducts passing through unconditioned spaces must be insu-
lated 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 appli-
cable 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 care-
ful when placing any sheet metal parts on such roof.
UNITS WITH ACCESSORY OR OPTIONAL ELECTRIC
HEATERS
Horizontal applications require a minimum clearance to
combustible surfaces of 1 in. (25 mm) from duct for first 12
in. (305 mm) away from unit. Vertical applications do not re-
quire a minimum clearance.
Minimum clearance is not required around ductwork.
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 re-
quired. Rollers may be used to move unit across a roof. Level
by using unit frame as a reference. See Table 2 and Fig. 7 for
additional information.
Lifting holes are provided in base rails as shown in Fig. 7.
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 drain pan can be
tightened with a 1 / -in. square socket drive extension. For fur-
2
ther details see Step 9 — Install External Condensate Trap
and Line on page 14.
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: / in. (6.4 mm) clearance between the roof
1
4
curb and the base rail inside the front and back, 0.0 in. clear-
ance 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 3
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
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.
After unit is in position, remove rigging skids and
shipping materials.
11
CAUTION
5 / in. (84 mm).
16
CAUTION