72
Packaged Rooftop Cooling Unit with
Gas Heat — Constant Volume Application
HVAC Guide Specifications
Size Range:
3 to 12
1
/
2
Tons, Nominal Cooling
50,000 to 250,000 Btuh,
Nominal Input Heating
Carrier Model Number:
48HJD,
48HJE,
48HJF
Part 1 — General
1.01 SYSTEM DESCRIPTION
Outdoor rooftop- or slab-mounted, electrically con-
trolled heating and cooling utilizing a scroll compres-
sor for cooling duty and gas combustion for heating
duty. Unit shall discharge supply air vertically or hor-
izontally as shown on contract drawings.
1.02 QUALITY ASSURANCE
A. Unit shall be rated in accordance with ARI
Standards 210/240 or 360 and 270.
B. Unit shall be designed to conform to ASHRAE 15,
latest revision, and in accordance with UL 1995.
C. Unit shall be UL tested and certified in accordance
with ANSI Z21.47 Standard and UL listed and certi-
fied under Canadian Standards as a total package
for safety requirements.
D. Roof curb shall be designed to conform to NRCA
Standards.
E. Insulation and adhesive shall meet NFPA 90A
requirements for flame spread and smoke
generation.
F. Unit casing shall be capable of exceeding Federal
Test Method Standard No. 141 (Method 6061)
500-Hour Salt Spray Test.
G. Each 48HJ unit is subjected to completely auto-
mated run testing on the assembly line. Each unit
contains a factory-supplied printout indicating tested
pressures, amperages, data, and inspectors; provid-
ing certification of the unit status at the time of
manufacture.
1.03 DELIVERY, STORAGE, AND HANDLING
Unit(s) shall be stored and handled per manufac-
turer’s recommendations.
Part 2 — Products
2.01 EQUIPMENT (STANDARD)
A. General:
Factory-assembled, single-piece heating and cooling
unit. Contained within the unit enclosure shall be all
factory wiring, piping, controls, refrigerant charge
(R-22), and special features required prior to field
start-up.
B. Unit Cabinet:
1. Unit cabinet shall be constructed of galvanized
steel, bonderized and coated with a baked
enamel finish on all externally exposed sur-
faces, and have primer-coated interior surfaces
on all panels.
2. Evaporator-fan cabinet interior shall be insu-
lated with a minimum
1
/
2
-in. thick flexible fiber-
glass insulation coated on the air side.
Aluminum foil-faced fiberglass insulation shall
be used in the heating compartment.
3. Cabinet panels shall be easily removable for
servicing.
4. Holes shall be provided in the base rails for rig-
ging shackles to facilitate overhead rigging, and
forklift slots shall be provided to facilitate
maneuvering.
5. Unit shall have a factory-installed, sloped con-
densate drain pan made of a non-corrosive
material, providing a minimum
3
/
4
-in. connec-
tion with both vertical and horizontal drains and
shall comply with ASHRAE 62.
6. Unit shall have factory-installed filter access
panel to provide filter access with tool-less
removal.
7. Unit shall have standard thru-the-bottom power
connection capability.
C. Fans:
1. Indoor blower (evaporator fan) shall be of the
belt-driven, double inlet, forward-curved centrif-
ugal type. Belt drive shall include an adjustable-
pitch motor pulley.
2. Indoor blower (evaporator fan) shall be made
from steel with a corrosion-resistant finish and
shall be dynamically balanced.
3. Bearings shall be of the sealed, permanently
lubricated, ball-bearing type for longer life and
lower maintenance.
4. Condenser fan shall be of the direct-driven pro-
peller type and shall discharge air vertically
upward.
5. Condenser fan shall have blades riveted to cor-
rosion-resistant steel spiders and shall be
dynamically balanced.
6. Condenser-fan motor shall be totally enclosed.
7. Induced draft blower shall be of the direct-
driven, single inlet, forward curved, centrifugal
type, shall be made from steel with a corrosion-
resistant finish, and shall be dynamically
balanced.
D. Compressor(s):
1. Fully hermetic scroll type, internally protected.
2. Factory rubber-shock mounted and internally
spring mounted for vibration isolation.
3. On independent circuits (008-014).
E. Coils:
1. Evaporator and condenser coils shall have alu-
minum plate fins mechanically bonded to
enhanced copper tubes with all joints brazed.
2. Tube sheet openings shall be belled to prevent
tube wear.
3. Evaporator coil shall be of the face-split design.
Guide specifications
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