Guide specifications, System Description

Guide specifications

Indoor Self-Contained Air-Cooled Unit Constant Volume Application

HVAC Guide Specifications

Size Range: 5 to 20 Tons

Carrier Model Number: 50XCA

Part 1 — General

1.01SYSTEM DESCRIPTION

Indoor packaged vertical air-cooled cooling unit using hermetic scroll compressors and built-in con- denser fan for cooling duty. Unit shall discharge sup- ply air vertically or horizontally and condenser air horizontally as shown on contract drawings.

1.02QUALITY ASSURANCE

A.Units shall be rated in accordance with AHRI Stan- dard 340/360, latest edition, as appropriate.

B.Unit shall be designed to conform to ANSI/ ASHRAE 15, latest revision safety code, and UL Standard 1995, and shall be UL listed under both American and Canadian Standards.

C.Unit shall be built in an ISO 9001:2000 certified manufacturing facility and shall be fully run-tested.

D.Insulation, adhesive, and liner system shall meet NFPA 90A requirements for flame spread and smoke generation.

1.03 DELIVERY, STORAGE, AND HANDLING

Units shall be stored and handled according to man- ufacturer’s recommendations.

Part 2 — Products

2.01EQUIPMENT

A.General:

Factory-assembled, single-piece, air-cooled cooling unit. Unit shall consist of scroll refrigerant compres- sor(s), indoor fan section with belt drive centrifugal fans and motor, evaporator coil section with direct expansion coil and drain pan, air-cooled condenser fan section with belt drive centrifugal fans and motor, factory wiring, piping and controls, and a system charge of refrigerant (R-410A). Unit may be used with or without return ductwork.

B.Unit Cabinet:

1.Cabinet shall be constructed of minimum 18 gage zinc surface alloyed steel with a baked enamel finish. Unit shall be capable of with- standing ASTM B117 500-hour salt spray test.

2.Cabinet shall be fully insulated.

3.Unit drain pan shall have positive double slope to the drain to prevent standing water in pan.

4.Panels for servicing shall be easily removable.

C.Evaporator Fan Section:

1.Fans shall be double inlet, centrifugal wheel with forward curved blades designed for contin- uous operation. Fan wheel and scroll shall be constructed of steel with corrosion resistant fin- ish, and statically and dynamically balanced.

2.Fan shall be belt drive with an adjustable pitch motor pulley and fixed pitch fan pulley, with permanently lubricated ball-bearing type bear- ings. Units larger than 12 tons use pillow block bearings.

3.Motor shall be 3-phase high-efficiency NEMA frame TEFC (totally enclosed fan cooled) of the same voltage as the compressor(s). Motor shall have permanently lubricated ball bearings.

D.Compressor:

Hermetic scroll compressors shall be internally pro- tected with high pressure relief. Compressors shall be factory rubber shock mounted with internal spring vibration isolators.

E.Coils:

1.Evaporator and condenser coil shall have alumi- num plate fins mechanically bonded to seamless copper tubes with all joints brazed. Tube sheet openings shall be swaged to prevent tube wear. Coils shall be face split design.

2.Direct expansion coil shall be designed and tested in accordance with ANSI/ASHRAE 15, latest revision safety code.

3.Coil and drain pan shall be accessible through service access panels for cleaning.

F.Filter:

Filter frame shall be installed upstream of the cool- ing coil, designed to take a 1-in. or 2-in. thick clean- able or disposable type commercially available filter. Filters shall be accessible from either side of the unit and filter rack shall be usable with ducted or free return. Disposable filters will be supplied with the unit.

G.Condenser:

2.Fan shall be belt drive with an adjustable pitch motor pulley and fixed pitch fan pulley, with permanently lubricated, ball-bearing type bear- ings. Units larger than 12 tons use pillow block bearings.

3.Motor shall be 3-phase high-efficiency NEMA frame TEFC (totally enclosed fan cooled) of the same voltage as the compressor(s). Motor shall have permanently lubricated ball bearings.

H.Operating Characteristics:

Unit shall be capable of providing a constant volume of conditioned air at a specified static pressure within the unit’s normal operating range. Unit shall have dual-stage cooling capacity control on all units sizes 12 to 24. Each compressor shall be on an independent refrigerant circuit. Unit shall be capable of starting and operating at up to 115 F outdoor