Guide specifications
Packaged Heating/Cooling Units
Constant Volume Application
HVAC Guide Specifications
Size Range: 1
1
⁄
2
to 5 Tons, Nominal Cooling
40,000 to 140,000 Btuh,
Nominal Input Heating
Carrier Model Number: 48SS
Part 1 — General
1.01 SYSTEM DESCRIPTION
Outdoor rooftop mounted, gas heating/electric cool-
ing unit utilizing a rotary, reciprocating, or scroll her-
metic compressor for cooling duty. Unit shall discharge
supply air downward or horizontally as shown on con-
tract drawings. Outdoor fan/coil section shall have a
blow-thru design for minimum sound levels.
1.02 QUALITY ASSURANCE
A. Unit shall be rated in accordance with ARI Standards
210/240 and 270.
B. Unit shall be designed in accordance with UL Stand-
ard 564.
C. Unit shall be UL listed and CSA certified 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 re-
quirements for flame spread and smoke generation.
F. Cabinet insulation shall meet ASHRAE standard
no. 62.
1.03 DELIVERY, STORAGE, AND HANDLING
Unit shall be stored and handled per manufacturer’s
recommendations.
Part2—Products
2.01 EQUIPMENT
A. General:
Factory-assembled, single-piece heating and cooling
unit. Contained within the enclosure shall be all fac-
tory 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 phosphated,
zinc-coated prepainted steel, capable of withstand-
ing 500 hours in salt spray.
2. Cabinet panels shall be easily removed for
servicing.
3. Indoor blower compartment interior cabinet sur-
faces shall be insulated with a minimum
1
⁄
2
-in. thick,
flexible cleanable insulation, coated on the air side.
Aluminum foil-faced cleanable insulation shall be
used in the entire section.
4. Unit shall utilize a sloped condensate drain pan.
External trap required.
C. Fans:
1. The indoor (evaporator) fan shall be 2- or 3-speed
direct-drive, as shown on equipment drawings.
2. Fan wheel shall be made from steel, be double-
inlet type with forward curved blades with corro-
sion resistant finish and be dynamically balanced.
3. Outdoor (condenser) fan shall be of the direct
driven, propeller type with aluminum blades riv-
eted to corrosion resistant steel spiders, be dy-
namically balanced, and discharge air vertically
upwards and horizontally.
D. Compressor:
1. Fully hermetic compressor with factory-installed vi-
bration isolation.
2. Rotary compressors shall be standard on unit
size 018. Reciprocating compressors shall be stand-
ard on unit sizes 024-042. Scroll compressors shall
be standard on unit sizes 048 and 060.
E. Coils:
Evaporator and condenser coils shall have aluminum
plate fins mechanically bonded to seamless copper
tubes with all joints brazed. Tube sheet openings shall
be belled to prevent tube wear.
F. Heating Section:
1. Induced-draft combustion type with energy saving
direct spark ignition system and redundant main
gas valve.
2. Induced-draft motors shall be provided with solid-
state hall effects sensor to ensure adequate airflow
for combustion.
3. The heat exchangers shall be constructed of alu-
minized steel for corrosion resistance.
4. Burners shall be of the in-shot type constructed of
aluminum coated steel.
5. Integrated gas control board shall provide control
of heating and simplify troubleshooting through
its built-in diagnostic function. The IGC shall pro-
vide timed control of indoor-fan functioning and
burner ignition. A light-emitting diode (LED) shall
provide diagnostic information. The IGC board
shall also contain anti-short cycle protection for
gas heat operation.
6. All gas piping and electric power shall enter the
unit cabinet at a single location.
G. Refrigerant Components:
Refrigerant components shall be of the Acutrol™ feed
system type.
H. Controls:
Unit shall be complete with self-contained low-voltage
control circuit.
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