HVAC Guide Specifications
Indoor Packaged Water-Cooled UnitConstant Volume Application
SizeRange:
5 to 20 Tons
Carrier Model Number:
50BRN
Part 1 — General
1.01 SYSTEM DESCRIPTION
Indoor vertical water-cooled packaged cooling unitutilizing a hermetic scroll compressor(s) for coolingduty.
1.02 QUALITY ASSURANCE
A. Units shall be rated in accordance with ARI Standard210/240 or 360.
B. Unit shall be designed to conform to ANSI/ASHRAE 15, latest revision safety code, and ULStandard 1995, and shall be UL listed under bothAmerican and Canadian Standards.
C. Insulation and adhesive shall meet NFPA90A requirements for flame spread and smokegeneration.
1.03 DELIVERY, STORAGE AND HANDLING
Units shall be stored and handled according to manufacturer’srecommendations.
Part 2 — Products
2.01 EQUIPMENT
A. General:
Factory-assembled, single-piece, water-cooled coolingunit consisting of scroll refrigerant compressor(s), fan section with belt drive centrifugal fan(s)and motor, coil section with direct expansion coiland drain pan, water-cooled compact brazed platecondenser, factory wiring, piping and controls, anda system charge of refrigerant (R-22) included. Unitmay be used with or without ductwork.
B. Unit Cabinet:
1. Cabinet shall be constructed of zinc surfacealloyed steel with a baked enamel finish. Unitshall be capable of withstanding ASTM B117500-hour salt spray test.
2. Cabinet shall be fully insulated. Evaporator sectionshall have a full metal liner and condensersection shall have full sound attenuating insulation.Units shall be capable of withstanding ARIinsulating efficiency test at minimum airflowwithout cabinet sweating.
3. Unit drain pan shall have positive slope to thedrain to prevent standing water in pan.
4. Panels for servicing shall be easily removableusing a single wrench size.
5. Return grilles on all units except sizes 016 and024.
C. Fan Section:
1. Fan shall be double inlet, centrifugal wheel withforward curved blades, designed for continuousoperation. Fan wheel and scroll shall beconstructed of steel with corrosion resistant finish,and statically and dynamically balanced.
2. Fan shall be belt drive with an adjustable pitchmotor pulley, with permanently lubricated, ballbearingtype bearings.
3. Fan shall be easily field convertible from verticalto horizontal discharge.
D. Compressor:
Hermetic scroll compressors, internally protectedwith high pressure relief. Compressors shall be factoryrubber shock mounted with internal springvibration isolators.
E. Coil:
1. Evaporator coil shall have aluminum plate finsmechanically bonded to seamless copper tubeswith all joints brazed. Tube sheet openings shallbe swaged to prevent tube wear.
2. Direct expansion coil shall be designed andtested in accordance with ANSI/ASHRAE 15,latest revision safety code.
3. Coil and drain pan shall be accessible throughservice access panels for cleaning.
F. Filter:
Filter frame shall be installed upstream of the coolingcoil, to take a 1-in. thick cleanable or disposabletype commercially available filter. Disposable filterswill be supplied with the unit.
G. Condenser:
Condenser shall be single pass, water-cooled, ANSItype 316, stainless steel brazed plate constructionand shall provide positive subcooling of liquidrefrigerant. Condenser shall have a maximum workingwater side pressure of 400 psig. An independentcondenser shall be provided for each refrigerantcircuit.
H. Operating Characteristics:
Unit shall be capable of providing a constant volumeof conditioned air at a specified static pressurewithin the unit’s normal operating range. Air dischargeto be horizontally free blow, or verticallythrough ductwork as shown on contract drawings.Unit shall have single-stage cooling capacity control(sizes 006,008) or 2-stage capacity control (sizes012-024). Unit sizes 012-016 shall have 2 independentrefrigerant circuits. Size 024 shall have 3 independentrefrigerant circuits.
I. Controls and Safeties:
Unit shall have one of the following control systems:
1. Unit-mounted thermostat mounted in the unitreturn air. Unit shall be furnished with a factory-mountedfan control switch to control fan operationand turn off the unit.
2. Room-mounted thermostat shall be mounted inthe conditioned space. Thermostat shall beeither electromechanical or electronic type.Thermostat subbase shall control fan operationand be capable of turning unit on and off.
3. Room-mounted thermostat with communicatingcapability. This thermostat shall operate likethe standard room-mounted thermostat andshall provide the additional benefit of being ableto communicate with building systems to facilitateunit operation and control.In addition, units shall have the following factory-installedsafeties: high and low-pressure switches,overtemperature, current lockout, and inherentautomatic fan motor overload.
J. Electrical Requirements:
All electrical wiring shall enter the unit cabinet at asingle location. Control circuit is 24-v, suitable forpowering a field-supplied 24-v thermostat.
K. Refrigerant Components:
Refrigerant circuit components include thermalexpansion valve(s), filter drier(s), and charging servicevalve(s).
L. Special Features:
1. Air Discharge Plenum:
Plenum shall be provided to permit free-blowhorizontal air distribution with movable vanes toadjust airflow in horizontal and vertical direction.Plenum is field-installed and shall be fullyinsulated.
2. Heating Coil:
Field-installed steam coil shall be one row, orhot water coil will be 2 rows with copper tubealuminum spiral fins and a galvanized steel casing.Fins shall be bonded to tubes by mechanicalexpansion. Coil to be leak tested at 350 psigair pressure submerged in water and chargedwith dry air. Coil shall mount internal to theunit.
3. Thermostats:
A complete line of thermostats shall beavailable to meet any application controlrequirements.
4. Rear Return Filter Box:
A rear return filter box is available for unit sizes006 to 014 to provide side access filter rackwhen air is through rear return connection.