Alternate Unit Support (In Lieu Of Curb Or Slab Mount); Step 5 - Field Fabricate Ductwork; Units With Accessory Or Optional Electric Heaters; Step 6 - Rig And Place Unit - Carrier WeatherMaster 50HC04 Installation Instructions Manual

Fig. 5 — Unit Leveling Tolerances
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
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.
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
A-B B-C A-C
0.5 (13) 1.0 (25) 1.0 (25)
UNITS WITH ACCESSORY OR OPTIONAL ELECTRIC
HEATERS
All installations require a minimum clearance to combusti-
ble surfaces of 1 in. (25 mm) from duct for first 12 in.
(305 mm) away from unit.
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.
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 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.
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. Rig-
ging materials under unit (cardboard or wood) must be re-
moved PRIOR to placing the unit on the roof curb. Level by
using unit frame as a reference. See Table 2 on page 6 and
Fig. 6 for additional information.
Lifting holes are provided in base rails as shown in Fig. 6.
Refer to rigging instructions on unit.
Before setting the unit onto the curb, recheck gasketing on
curb.
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 panels or pack-
aging are 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.
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WARNING
CAUTION