Slab Mount (Horizontal Units Only); Alternate Unit Support (In Lieu Of Curb Or Slab Mount); Step 5 - Field Fabricate Ductwork; For Units With Accessory Electric Heaters - Bryant 549J Series Installation Instructions Manual

Curb should be level. This is necessary for unit drain to
function properly. Unit leveling tolerances are shown in
Fig. 8. Refer to Accessory Roof Curb Installation
Instructions for additional information as required.
Fig. 8 - - 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 package
must be installed before the unit is set 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.
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.
MAXIMUM ALLOWABLE
DIFFERENCE IN. (MM)
A-B B-C A-C
0.5" (13) 1.0" (25) 1.0" (25)
a50--- 9658
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.
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 Electric Heaters —
All installations require a minimum clearance to
combustible 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.
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
CAUTION
!
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.
Keep unit upright and do not drop. Spreader bars are not
required if top crating is left on unit. Rollers may be used to
move unit across a roof. Level by using unit frame as a
reference. See Table 4 and Fig. 9 for additional information.
Lifting holes are provided in base rails as shown in Fig. 9.
Refer to rigging instructions on unit.
Rigging materials under unit (cardboard to prevent base
pan damage) must be removed PRIOR to placing the unit
on the roof curb.
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