27Packaged Heat Pump UnitsConstant Volume ApplicationHVAC Guide SpecificationsSize Range: 2 to 5 Tons, Nominal CoolingCarrier Model Number: 50JZPart 1—GeneralSYSTEM DESCRIPTIONOutdoor rooftop or ground mounted, heat pump unitutilizing a hermetic compressor for heating and cool-ing duty and optional electric heating. Unit shall dis-charge supply air vertically or horizontally as shownon contract drawings. Outdoor fan/coil section shallhave a draw-thru design with vertical discharge forminimum sound levels.QUALITY ASSURANCEA. Unit shall be rated in accordance with ARI Standards210/240-94 and 270-95.B. Unit shall be designed in accordance with UL Standard1995.C. Unit shall be manufactured in a facility registered toISO 9001 manufacturing quality standard.D. Unit shall be UL listed and c-UL certified as a totalpackage 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 HANDLINGUnit shall be stored and handled per manufacturer’srecommendations.Part 2 — ProductsEQUIPMENTA. General:Factory-assembled, single-piece, heat pump unit. Con-tained within the enclosure shall be all factory wiring,piping, controls, refrigerant charge (R-410A), and spe-cial 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 hrs of salt spray.2. Normal service shall be through a single removablecabinet panel.3. The unit shall be constructed on a rust proof basep-an that has an externally trapped, integrated slopeddrain pan.4. Indoor fan compartment top surface shall be insulat-ed with a minimum 1/2-in. thick, flexible fiberglassinsulation, 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-rigidfoil-faced board capable of being wiped clean. Alu-minum foil-faced fiberglass insulation shall be usedin the entire indoor air cavity section.5. Unit shall have a field-supplied condensate trap.C. Fans:1. The indoor fan shall be 3-speed, direct-drive, asshown on equipment drawings.2. Fan wheel shall be made from steel, and shall bedouble-inlet type with forward curved blades withcorrosion resistant finish. Fan wheel shall be dy-namically balanced.3. Outdoor fan shall be direct drive propeller type withaluminum blades riveted to corrosion resistant steelspiders, be dynamically balanced, and discharge airvertically.D. Compressor:1. Fully hermetic compressors with factory-installedvibration isolation.2. Scroll compressors shall be standard on all units.E. Coils:Indoor and outdoor coils shall have aluminum platefins mechanically bonded to seamless copper tubeswith all joints brazed. (Copper/copper and vinyl-coat-ed construction available as option.) Tube sheet open-ings shall be belled to prevent tube wear.F. Refrigerant Metering Device:Refrigerant metering device shall be of the single bodyfixed orifice feed type.G. Filters:Filter section shall consist of field-installed, throw-away, 1-in. thick fiberglass filters of commerciallyavailable 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.3. Unit shall provide High and Low/Loss-of-ChargePressure Safety Protection.I. Operating Characteristics:1. Unit shall be capable of starting and running at125°F ambient outdoor temperature, exceedingmaximum load criteria of ARI Standard 240-94.2. Compressor with standard controls shall be capable ofoperation down to 40° F ambient outdoor temperaturein cooling and -10°F in heating.3. Unit shall be provided with 30 or 60-sec fan timedelay after the thermostat is satisfied.J. Electrical Requirements:All unit power wiring shall enter the unit cabinet at asingle location.K. Motors:1. Compressor motors shall be of the refrigerant-cooled type with line-break thermal and currentoverload protection.Guide specifications