24
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 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 dimen-
sions 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 ap-
plicable 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.
UNITS WITH ACCESSORY OR OPTIONAL ELECTRIC
HEATERS
Minimum clearance is not required around ductwork.
Step 6 — Rig and Place Unit
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 2
on page 19 and Fig. 22 for additional information.
Lifting holes are provided in base rails as shown in Fig. 22. Refer
to rigging instructions on unit.
Before setting the unit onto the curb, recheck gasketing on curb.
Fig. 22 — Rigging Details
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.
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.
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 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.
NOTES:
1. Dimensions in ( ) are in millimeters.
2. Hook rigging shackles through holes in base rail, as shown in detail “A.” Holes in base rails are centered around the unit center of
gravity. Use wooden top to prevent rigging straps from damaging unit.
UNIT
MAX WEIGHT
DIMENSIONS
A B C
LB KG IN. MM IN. MM IN. MM
50LC-*14 2004 911 127.8 3249 59.1 1501 52.3 1328
50LC-*17 2246 1021 141.5 3595 65.5 1664 60.3 1532
50LC-*20 2353 1069 141.5 3595 65.5 1664 60.3 1532
50LC-*24 2499 1136 157.8 4007 72.8 1849 60.3 1532
50LC-*26 2643 1201 157.8 4007 72.8 1849 60.3 1532
"B"
"C"
"A"
(914-1371)
36"-54"
DETAIL A
SEE DETAIL A
PLACE ALL SEAL STRIP
IN PLACE BEFORE PLACING
UNIT ON ROOF CURB.
DUCT END
To Next Page
Loading...
