Carrier 48KHA - Manual (Page 3)

ROOFTOP INSTALLATION
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When installing a Model 48KHA,KLA end dis­
charge unit with a field-supplied downflow plenum,
a field-supplied roof-mounting curb must be in­
stalled on and flashed into roof before unit installa­
tion. When installing a Model 48KHA,KLA end
discharge unit without a downflow plenum, place
unit on a level base that provides proper support.
On flat roofs be sure unit is located at least 4 in.
above highest expected water level on roof to
prevent flooding. Consult local codes for additional
installation requirements.
GROUND LEVEL INSTALLATION — Place unit
on a solid, level concrete pad that is a minimum
of 4 in. thick and that extends approximately 2 in.
beyond casing on all sides of unit. Do not secure unit
to pad except when required by local codes.
CLEARANCES — Required minimum operating
and service clearances are shown in Fig. 4 for pro­
viding adequate combustion, ventilation and con­
denser air.
Condenser fan discharges through top of unit.
Ensure that fan discharge does not recirculate to
condenser coil. Do not locate unit in either a corner
or under a complete overhead obstruction. Mini­
mum clearance under a partial overhang (such as a
typical house roof overhang) is 3 ft above vent cap.
Maximum horizontal extension of a partial over­
hang must not exceed 4 feet.
Do not locate unit where water, falling ice or snow
from an overhang or roof will damage or flood the
unit. Do not locate unit where grass, shrubs or other
plants will interfere with the airflow either into or
out of unit. Do not install unit on carpeting, tile or
other combustible material other than wood
flooring.
CONDENSATE DISPOSAL
NOTE: Be sure condensate water disposal methods
comply with local codes, restrictions and practices.
Models 48KHA,KLA dispose of condensate
water through a 3/4-in. MPT drain fitting. See
Fig. 4 for location.
Install a 3-in. trap at the drain fitting to ensure
proper drainage. See Fig. 3. Make sure trap outlet
is at least 2 in. lower than unit drain pan connection
to prevent pan from overflowing. Prime trap with
water.
If installation requires draining the condensate
water away from unit, connect a drain tube using a
minimum of 7/8-in. OD copper tubing, 3/4-in.
galvanized pipe or 7/8-in. plastic pipe. Do not
undersize the tube. Pitch drain tube downward at a
slope at least one in. for every 10 ft of horizontal run.
Be sure to check drain tube for leaks.
Condensate water can be drained directly onto
roof in rooftop installations (where permitted) or
onto a gravel apron in ground level installations.
When using a gravel apron, make sure it slopes away
from the unit.
TO DRAIN
VENTING — The vent cap, combustion air shroud
and flue assembly are shipped in either the blower or
control compartment. Vent screen is taped to blower
housing. Remove access doors to locate assemblies.
See Fig. 4 for door locations.
NOTE: Screw holes in flue assembly and unit top
are positioned to ensure proper orientation when
installed. Refer to Fig. 5 and install vent cap as
follows;
1. Place combustion air shroud over combustion air
opening in unit top, and line up screw holes in
shroud with holes in top. Secure shroud to top,
using screws with rubber washers (provided).
2. The flue gasket is shipped in the literature as­
sembly envelope. Place gasket and flue assembly
through hole in combustion air shroud, orient
screw holes in base of flue assembly with holes in
unit top, and secure gasket and flue assembly to
unit top, using screws provided.
3. Form flat wire screen (provided) into circular
shape around protruding lip of combustion-air
shroud and bend wire ends through holes of
screen mesh to secure screen in place. Make sure
that no sharp edges are left exposed.
4. Place vent cap sleeve inside flue assembly. Orient
spring clip of vent cap with slot in assembly. Be
sure clip snaps into slot to secure clip onto
assembly.