27
Packaged Heat Pumps
Constant Volume Application
HVAC Guide Specifications
Size Range: 2 to 5 Tons, Nominal Cooling
Carrier Model Number: 50JX
Part 1—General
SYSTEM DESCRIPTION
Outdoor packaged air to air heat pump unit utilizing a
hermetic compressor for cooling duty and optional elec-
tric heating. Unit shall discharge supply air vertically or
horizontally as shown on contract drawings. Outdoor
fan/coil section shall have a draw-thru design with ver-
tical discharge for minimum sound levels.
QUALITY ASSURANCE
A. Unit shall be rated in accordance with ARI Standards
210/240-94 and 270-95.
B. Unit shall be designed in accordance with UL Standard
1995.
C. Unit shall be manufactured in a facility registered to
ISO 9001 manufacturing quality standard.
D. Unit shall be UL listed and c-UL certified as a total
package for safety requirements.
E. Roof curb shall be designed to conform to NRCA Stan-
dards.
F. Insulation and adhesives shall meet NFPA 90A re-
quirements for flame spread and smoke generation.
G. Cabinet insulation shall meet ASHRAE Standard 62P.
DELIVERY, STORAGE AND HANDLING
Unit shall be stored and handled per manufacturer’s
recommendations.
Part 2 — Products
EQUIPMENT
A. General:
Factory-assembled, single-piece, heat pump unit. Con-
tained within the 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 phosphated,
zinc-coated, pre-painted steel capable of withstand-
ing 500 hours of salt spray.
2. Normal service shall be through a single removable
cabinet panel.
3. The unit shall be constructed on a rust proof unit
base that has an externally trapped, integrated
sloped drain.
4. Indoor fan compartment top surface shall be insulat-
ed with a minimum 1/2-in. thick, flexible fiberglass
insulation, coated on the air side and retained by ad-
hesive and mechanical means. The indoor wall sec-
tions will be insulated with a minimum semi-rigid
foil-faced board capable of being wiped clean. Alu-
minum foil-faced fiberglass insulation shall be used
in the entire indoor air cavity section.
5. Unit shall have a field-supplied condensate trap.
6. Metal Insulated Duct Covers for side discharge will
be standard on all sizes.
7. Unit Insulation conforms to ASHRAE 62P.
C. Fans:
1. The indoor fan shall be 3-speed, direct-drive, as
shown on equipment drawings.
2. Fan wheel shall be made from steel and shall be
double-inlet type with forward curved blades with
corrosion resistant finish. Fan wheel shall be dy-
namically balanced.
3. Outdoor fan shall be direct drive propeller type with
aluminum blades riveted to corrosion resistant steel
spiders, be dynamically balanced, and discharge air
vertically.
D. Compressor:
1. Fully hermetic compressors with factory-installed
vibration isolation.
2. Scroll compressors shall be standard on all units.
3. Compressor Protection:
Defrost control shall protect compressor by pre-
venting “short cycling.”
E. Coils:
Indoor and outdoor coils shall have aluminum plate
fins mechanically bonded to seamless copper tubes
with all joints brazed. (Copper/copper and vinyl-
coated construction available as option.) Tube sheet
openings shall be belled to prevent tube wear.
F. Refrigerant Metering Device:
Refrigerant metering device shall be of the fixed ori-
fice feed type.
G. Filters:
Filter section shall consist of field-installed, throw-
away, 1-in. thick fiberglass filters of commercially
available sizes.
H. Controls and Safeties:
1. Unit controls shall be complete with a self-
contained, low voltage control circuit.
2. Units shall incorporate an internal compressor pro-
tector that provides reset capability.
I. Operating Characteristics:
1. Unit shall be capable of starting and running at
125°F ambient outdoor temperature per maximum
load criteria of ARI Standard 240-94.
2. Compressor with standard controls shall be capa-
ble of operation down to 40°F ambient outdoor
temperature in cooling mode.
3. Unit shall be provided with 60-second fan time de-
lay after the thermostat is satisfied.
J. Electrical Requirements:
All unit power wiring shall enter the unit cabinet at a
single location.
K. Motors:
1. Compressor motors shall be of the refrigerant-
cooled type with line-break thermal and current
overload protection.
Guide specifications
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