Carrier 50KC*A/B0 Series, Installation Instructions Manual

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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 0.4-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 dimen-
sions 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 insulat-
ed 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.
FOR UNITS WITH ACCESSORY ELECTRIC HEATERS
All installations require a minimum clearance to combustible
surfaces of 1-in. (25 mm) from duct for the 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.
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. 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.
Rigging materials under unit (cardboard or wood to prevent
base pan damage) 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 be-
fore setting the unit in place. The red drain pan plug can be
tightened with a 1 /
2
-in. square socket drive extension. For fur-
ther details see “Step 10 — Install External Condensate Trap
and Line” on page 12.
POSITIONING ON CURB
Position unit on roof curb so that the following clearances are
maintained: 1 /
4
-in. (6.4 mm) clearance between the roof curb
and the base rail inside the front and rear, 0.0-in. clearance
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 1 /
4
-in. (6.4 mm).
Although unit is weatherproof, guard against water from
higher level runoff and overhangs.
After unit is in position, remove rigging skids and shipping
materials.
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.
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
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.