ANSI- ARI 430-99

4100 N. FAIRFAX DR., STE. 200 ! ARLINGTON, VIRGINIA 22203

ANSI/ARIStandard 430-1999

1999

STANDARD for

CENTRALSTATION AIR-HANDLINGUNITS

4100 N. FAIRFAX DR., STE. 200 ! ARLINGTON, VIRGINIA 22203

Price $15.00 (M) $30.00 (NM) Copyright 1999, by Air-Conditioning and Refrigeration InstitutePrinted in U.S.A. Registered United States Patent and Trademark Office

IMPORTANT

SAFETY RECOMMENDATIONS

It is strongly recommended that the product be designed, constructed, assembled and installed in accordance withnationally recognized safety requirements appropriate for products covered by this standard.

ARI, as a manufacturers' trade association, uses its best efforts to develop standards employing state-of-the-art andaccepted industry practices. However, ARI does not certify or guarantee safety of any products, components orsystems designed, tested, rated, installed or operated in accordance with these standards or that any testsconducted under its standards will be non-hazardous or free from risk.

ARI CERTIFICATION PROGRAM PROVISIONS

Scope of the Certification Program

The Certification Program includes all sizes of central station air-handling units as defined in Section 2.

Certified Ratings

The following Certification Program ratings are verified by test:

1. Fan Speed, rpm [rev/s]2. Brake Horsepower, bhp [W]

Note:

This standard supersedes ARI Standard 430-99.

TABLE OF CONTENTS

SECTION PAGE

Section 1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 3. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Section 4. Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Section 5. Test Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Section 6. Rating Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Section 7. Minimum Data Requirements for Published Ratings . . . . . . . . . . . . . . . . . . . . . . . 7

Section 8. Marking and Nameplate Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Section 9. Voluntary Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

FIGURES

Figure 1. Blow-Through Central Station Air-Handling Unit . . . . . . . . . . . . . . . . . . . . . . . . 2

Figure 2. Draw-Through Central Station Air-Handling Unit . . . . . . . . . . . . . . . . . . . . . . . . 2

Figure 3. Multiple Fan Outlet Test Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 4. Dimensions for Inlet Vane Proportionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 5. Draw-Through Unit With Air Flow Direction Change . . . . . . . . . . . . . . . . . . . . . 6

Figure 6. Fan and Unit Characteristics - Fan Rated and Unit Tested . . . . . . . . . . . . . . . . . 8

Figure 7. Fan and Unit Characteristics - Fan Rated and Unit Calculated . . . . . . . . . . . . . . 9

APPENDICES

Appendix A. References - Normative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Appendix B. References - Informative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Appendix C. Criteria for Proportionality - Informative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

FIGURES FOR APPENDICES

Figure C1. Dimensions Used for Proportionality Equations . . . . . . . . . . . . . . . . . . . . . . . . . 14

ANSI/ARI STANDARD 430-1999

1

CENTRAL STATION AIR-HANDLING UNITS

Section 1. Purpose

1.1 Purpose. The purpose of this standard is to establishfor central station air-handling units: definitions;classifications; requirements for testing and rating; minimumdata requirements for published ratings; marking andnameplate data; and conformance conditions.

1.1.1 Intent. This standard is intended for theguidance of the industry, including manufacturers,engineers, installers, contractors, and users.

1.1.2 Review and Amendment. This standard issubject to review and amendment as technologyadvances.

Section 2. Scope

2.1 Scope. This standard applies to central station air-handling units, as defined in Section 3.

2.2 Exclusions.

2.2.1 This standard does not apply to forced-circulation, free-delivery air-coolers for refrigeration,which are covered in ARI Standard 420.

2.2.2 This standard does not apply to unit heatersintended for free delivery of heated air or to room fan-coil air-conditioners as defined in ARI Standard 440.

2.2.3 This standard does not apply to units havingdirect expansion coils which are incorporated by themanufacturer in a matched split system air-conditioneror as otherwise defined in the product scope definitionof the ARI Unitary Small Equipment and Unitary LargeEquipment Sections and covered in ARI Standard210/240 or in ARI Standard 340/360.

2.2.4 This standard does not apply to unitventilators as defined in ARI Standard 840.

2.2.5 This standard does not apply to ratings forplenum (plug) and axial fans.

Section 3. Definitions

3.1 Definitions. All terms in this document will follow thestandard industry definitions in the current edition ofASHRAE Terminology of Heating, Ventilation, AirConditioning and Refrigeration unless otherwise definedin this section.

3.2 Central Station Air-Handling Unit. A factory-madeencased assembly consisting of a fan or fans and othernecessary equipment to perform one or more of thefunctions of circulating, cleaning, heating, cooling,humidifying, dehumidifying and mixing of air; and shall notcontain a source of cooling or heating other than gas orelectric heat. This device is capable of use with duct workhaving a total static resistance of at least 0.5 in. H2O [0.12kPa].

3.2.1 Blow-Through Central Station Air-HandlingUnit (see Figure 1). A unit containing a fan that doesnot have a ducted fan outlet.

3.2.2 Draw-Through Central Station Air-HandlingUnit (see Figure 2). A unit that has a ducted fan outlet.

3.2.3 Fan. An impeller and any other items, such ashousings and inlet vanes that are an integral part of theimpeller and/or housing that affect the basicperformance characteristics of the fan.

3.2.4 Unit Appurtenances . Equipment added forp urposes of control, isolation, safety, static pressureregain, wear, etc. Such appurtenances include coils,filters, dampers, air-mixers, sprays, eliminators, etc.

3.3 Published Rating. A statement of the assignedvalues of those performance characteristics, under statedrating conditions, by which a unit may be chosen to fit itsapplication. These values apply to all units of like nominalsize and type (identification) produced by the samemanufacturer. As used herein, the term "published rating"includes the rating of all performance characteristics shownon the unit or published in specifications, advertising orother literature controlled by the manufacturer at statedrating conditions.


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Figure 1. Blow-Through Central Station Air-Handling Unit

Figure 2. Draw-Through Central Station Air-Handling Unit


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3.3.1 Standard Rating. A rating based on testsperformed at Standard Rating Conditions.

3.3.2 Application Rating. A rating based on testsperformed at Application Rating Condit ions (other thanStandard Rating Conditions).

3.4 Rating Conditions. Any set of operating conditionsunder which a single level of performance results, and whichcauses only that level of performance to occur.

3.4.1 Standard Rating Conditions. Ratingconditions used as the basis of comparison forperformance characteristics.

3.5 "Shall," "Should," "Recommended" or "It IsRecommended." "Shall," "should," "recommended" or "itis recommended" shall be interpreted as follows:

3.5.1 Shall. Where "shall" or "shall not" is used fora provision specified, that provision is mandatory ifcompliance with the standard is claimed.

3.5.2 Should, Recommended or It is Recommended."Should," "recommended" or "it is recommended" isused to indicate provisions which are not mandatorybut which are desirable as good practice.

3.6 Standard Air. Air weighing 0.075 lb/ft3 [1.2 kg/m3]which approximates dry air at 70.0F [21.1C] and at abarometric pressure of 29.92 in. Hg [101.1 kPa].

Section 4. Classifications

4.1 Methods of Classification. Central station air-handling units may be classified according to the following:

A. Unit Type

1. Blow-through2. Draw-through

B. Application Type

1. Indoor2. Outdoor

Section 5. Test Requirements

5.1 Testing Requirements. All Standard Ratings shall beverified by tests conducted in accordance withANSI/ASHRAE Standard 51/AMCA Standard 210, except asmodified by 5.1.1.3.

5.1.1 Arrangements for Testing.

5.1.1.1 Single Outlet Draw-Through Units.Single outlet draw-through units shall be tested inaccordance with ANSI/ASHRAE Standard51/AMCA Standard 210.

5.1.1.2 Multiple Outlet Draw-Through Units.Multiple outlet draw-through units shall be testedas in 5.1.1.1 with each fan outlet ducted as shownin Figure 3 to the air flow measuring device.Individual fan outlet duct friction losses shall notbe included.

5.1.1.3 Blow-Through Units. Blow-throughunits shall be tested in accordance withANSI/ASHRAE Standard 51/AMCA Standard 210,except when an outlet chamber with multiplenozzles within the chamber is used. The testchamber cross-sectional area may be sized so thatthe maximum air velocity shall not exceed 400 fpm[2 m/s]. The test chamber height and width shallbe at least 5% greater than the respective heightand width of the duct connection at the testchamber. Duct area at the test chamber connectionplane cannot exceed the duct area at the unitconnection plane.

5.2 Description of Test Unit. This standard permits theomission of all appurtenances in the test unit except the coilsection, where used. Units to be tested shall contain thelargest cataloged face area coil for that size and arrangement(where applicable). The coil, fan sheave, and largestinternally mounted fan motor shall be mounted in their mostrestrictive cataloged location relative to the fan with the coilhaving a pressure drop of at least 0.075 in. H2O [0.019 kPa]at 500 fpm [2.54 m/s] coil face velocity with Standard Air.The coil shall be de-energized and the unit operatingwithout coil by-pass. In the case of a blow-through heating-cooling unit with multiple discharge path, all but the coolingcoil position shall be blocked and the unit tested withhorizontal air discharge. The pressure drop of the coilsshall have been determined in accordance with ARIStandard 410.

5.3 Extension of Test Data. Test data may be extended toother units in accordance with the provisions of 5.3.1, 5.3.2and 5.3.3.


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Figure 4. Dimensions for Inlet Vane Proportionality

Figure 3. Multiple Fan Outlet Test Configuration


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5.3.1 Application of Fan Laws to Units with InletVanes. Units with inlet vanes may be rated one of threeways: 1) using the fan laws as described by 5.3.2 forproportional units with proportional fans and inletvanes; 2) using the fan laws as described in 5.3.3 forp roportional units with nonproportional fans and inletvanes; or 3) using the fan laws by applying theappropriate inlet vane derate factors to units withoutinlet vanes rated per Sections 5.3.2 or 5.3.3 when theinlet vanes of the test unit are proportional to the inletvanes of the rated units. (Since all requirements forproportionality of cabinets, fan impellers, and housingare satisfied by provisions in either 5.3.2 or 5.3.3without inlet vanes, rated units with inlet vanes derivedby inlet vane derate factors must only meet inlet vaneproportionality criteria.)

Inlet vanes are considered to be proportional when theinlet vanes shall result in net air flow areas not less than92.5% of those derived from exact proportionality (asdefined in Section 5.3.2) when located within 0.5impeller diameter from the fan inlet. The test unit mustbe tested with vanes in the wide open position asspecified by the manufacturer. Vane shaft angle, 2,(with respect to fan shaft centerline) and the number ofvane blades for the rated unit must be the same as forthe test unit (see Figure 4). When evaluatinggeometrical proportionality of inlet vanes, the distancebetween vane and impeller (defined as dimensionsbetween impeller inlet plane and the closest point ofvanes with the vanes at wide open position, as set bythe manufacturer) and the distance bet ween cabinetside and fan inlet shall be considered.

The method of rating one unit with inlet vanes from thetest of another is described in Sections 5.3.3.1 through5.3.3.7.

5.3.2 Application of Fan Laws to ProportionalUnits with Proportional Fans. Test data may beextended by use of the fan laws to units containingfans, geometrically proportional fan cabinets andimpellers (see Appendix C). The fan impeller diameterof the unit to be calculated shall not be less than 65%of the fan impeller diameter of the test unit.

Fans are considered to be proportional when:

a. Impeller width, housing development radii,and housing width are proportional within 1.5%.

b. Fan housing outlet area is proportionalwithin 3%.

Fan cabinets are considered to be proportional when:

a. The clearance between the cabinet and thenearest fan housing are proportional orgreater.

b. The clearance between adjacent fanhousings, as measured parallel to the fanshaft, are proportional or greater.

c. The fan cabinet inlet and the fan cabinetoutlet air flow cross sectional areas are notless than 92.5% of the respectivegeometrically proportionate values.

d. Arrangement and location of int ernalbearings and their supports, inlet vanes,motors and drives, shall result in net airflow areas not less than 92.5% of thosederived from exact proportionality whenlocated within 0.5 impeller diameter of thefan inlet.

The basis for proportionality in every case shall be therespective impeller diameters; linear dimensions shallbe proportional to the diameter, and areas shall beproportional to the square of the diameter.

Single fan units may be rated from the test of a multiplefan unit provided that the units are otherwiseproportional and that the clearance between fans on themultiple fan unit is not more than twice theproportionate clearance between the cabinet and thefan housing on a single fan unit. In no case, shall theratings of a multiple fan unit from tests of a single fanunit be accepted. Air flow and fan shaft power areconsidered to be proportional to the number of fans.

Draw-through units which have a change in air-flowdirection between the coil and the fan (F igure 5) may berated from tests of units which do not have this flowdirection change (Figure 2) provided the plenumcausing the air direction change be considered anappurtenance and the effect of its application addedto those of other appurtenances as provided in 6.1.1There is no distinction in rating between a verticaldischarge and a horizontal discharge blow-throughunit.

The effects of proportions of bolts, nuts, rivets, etc.,shall be considered to be negligible.


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Figure 5. Draw-Through Unit With Air FlowDirection Change

5.3.3 Application of Fan Laws to ProportionalUnits with Non-Proportional Fans. The requirementsfor proportional fan impellers and scrolls set forth in5.3.2 are waived when all fans which are notgeometrically proportional are rated as fans alone (asdefined in 3.1) on the basis of tests performed inaccordance with ANSI/ASHRAE Standard 51/AMCAStandard 210. This applies only to fans of the sameblade design. Backward inclined fan impellers are notconsidered to be the same design as airfoil impellers.All other requirements of 5.3.2 shall be met.

The method of rating one unit from the test of anotheris as follows:

5.3.3.1 Using the rating performance curve ofthe fan alone (with or without inlet vanes) or unit

(without inlet vanes), create non-dimensionalperformance curves including percentage wide-open cfm, percentage blocked tight static pressureand percentage wide-open horsepower (see Figure6).

5.3.3.2 To derive the rating performance curvefor the test unit without coil, add the test unit staticpressure data to the static resistance of the dry coilas determined in accordance with ARI Standard410 (see Figure 6).

5.3.3.3 Superimpose on Figure 6 the unit ratingperformance curve (with or without inlet vanes) asderived under 5.3.3.2 at the same rpm [rev/s],expressing the values in percentages of wide-opencfm [m3/s], blocked tight static pressure and wide-


7

open horsepower of the fan alone (with or withoutinlet vanes) or unit (without inlet vanes) (seeFigure 6).

5.3.3.4 For the unit which is to be rated, but nottested use the rating performance curve of the fanalone (with or without inlet vanes) or unit (withoutinlet vanes) and plot percentages of wide open cfm[m3/s], blocked tight static pressure and wide-openhorsepower in the same way as for the solid linecurve in Figure 6 (see Figure 7).

5.3.3.5 Adjust the curves in Figure 7 by theperformance corrections between pairs of curvesas indicated in Figure 6. The resultant curves arethe calculated performance ratings for the unit nottested, expressed in percentages of performance ofthe fan alone (with or without inlet vanes) or unit(without inlet vanes) (see dashed lines in Figure 7).

5.3.3.6 To determine the actual ratingperformance values for the specific unit, multiplythe percentage values by the wide open cfm,blocked tight static pressure and wide openhorsepower of the specific unit's fan alone (with orwithout inlet vanes) or specific unit (without inletvanes) at the same rpm [rev/s] as in Figure 6performance curves.

5.3.3.7 The same procedure as for 5.3.3.6 appliesto multiple fan units, except that the cfm andhorsepower values for the fan alone (with orwithout inlet vanes) are multiplied by the numberof fans before applying to the unit, with therestrictions shown in the second paragraph of5.3.2. Single fan units may be rated from the testsof multiple fan units, but multiple fan units shallnot be rated from tests of single fan units.

Section 6. Rating Requirements

6.1 Air-Handling Ratings. Published air-handling ratingsshall be expressed in terms of the air quantity, scfm [m3/s];static pressure, in. H2O [kPa]; fan speed, rpm [rev/s]; and thepower required at the fan shaft, brake horsepower, bhp [W]based on the procedures outlined in 5.2 and 5.3 of thisstandard.

6.1.1 Effect of Appurtenances. The air-handlingratings referred to in 6.1, while based on tests with coilin place, represent the performance of the fan sectionalone without coil. Thus, as appurtenances such ascoils, filters, dampers, air-mixers, sprays, eliminators,etc., are added to the unit, their effects must be takeninto account in order to establish the overallperformance of the combined unit.

6.1.1.1 The manufacturer shall provide thenecessary published data and procedures wherebythe effects of the appurtenances offered may betaken into account. These effects shall be stated interms of pressure drop, in. H2O [kPa] measuredacross the appurtenance over the range of airquantities for which the unit is rated.

6.2 Air-Handling Tolerances. To comply with thisstandard, published air-handling ratings shall be such thatany unit shall produce its rated volume and pressure withrpm not exceeding the published rated rpm by more than 5%and brake horsepower, bhp [W] not exceeding the publishedrated brake horsepower, bhp [W] by more than 7.5%.

Section 7. Minimum Data Requirements forPublished Ratings

7.1 Minimum Data Requirements for Published Ratings.Wherever application ratings are published, they shallinclude a statement of the conditions at which the ratingsapply and be accompanied by the pertinent StandardRating(s), clearly designated as such. The followinginformation shall be published for all Standard Ratings.

a. Static Pressure, in. H2O [kPa]b. Air flow, cfm [m3/s]c. Fan speed, rpm [rev/s]d. Brake horsepower, bhp [W]


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Section 8. Marking and Nameplate Data

8.1 Marking and Nameplate Data. As a minimum thenameplate shall display the manufacturer's name and modeldesignation.

Recommended nameplate voltages for 60 Hertz systems shallinclude one or more of the utilization voltages shown inTable 1 of ARI Standard 110. Recommended nameplatevoltages for 50 Hertz systems shall include one or more ofthe utilization voltages shown in Table 1 of IEC StandardPublication 38.

Section 9. Voluntary Conformance

9.1 Conformance. While conformance with this standardis voluntary, conformance shall not be claimed or implied forproducts or equipment within its Purpose (Section 1) andScope (Section 2) unless such claims meet all of therequirements of the Standard.


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APPENDIX A. REFERENCES - NORMATIVEA1 Listed here are all standards, handbooks and otherpublications essential to the formation and implementationof the standards. All references in this appendix areconsidered as part of the standard.

A1.1 ANSI/AMCA Standard 210-1997, LaboratoryMethods of Testing Fans for Rating, 1997, andANSI/ASHRAE Standard 51, Laboratory Methods ofTesting Fans for Ratings, 1985 (a single combinedstandard), American National Standards Institute/AirMovement and Control Association, Inc., 11 West 42ndStreet, New York, NY 10036, U.S.A./ 30 West UniversityDrive, Arlington Heights, IL 60004, U.S.A./AmericanNational Standards Institute/American Society ofHeating, Refrigerating, and Air-Conditioning Engineers,Inc., 11 West 42nd Street, New York, NY 10036,U.S.A./1791 Tullie Circle N.E., Atlanta, GA 30329,U.S.A. A1.2 A R I S t a n d a r d 4 1 0 - 1 9 9 1 , Forced-Circulation Air-Cooling and Air-Heating Coils, 1991,4301 North Fairfax Drive, Suite 425, Arlington, VA22203, U.S.A.

A1.3 ARI Standard 110-1997, Air-Conditioning andRefrigerating Equipment Nameplate Voltages , 1997,Air-Conditioning and Refrigeration Institute, 4301 NorthFairfax Drive, Suite 425, Arlington, VA 22203, U.S.A.

A1.4 ASHRAE Terminology of Heating, Ventilation,Air-Conditioning and Refrigeration, 1991, SecondEdition, American Society of Heating, Refrigerating andAir-Conditioning Engineers, Inc., 1791 Tullie Circle N.E.,Atlanta, GA 30329, U.S.A.

A1.5 IEC Standard Publication 38, IEC StandardVoltages , 1983, International ElectrotechnicalCommission, 3, rue de Varembe, P.O. Box 131, 1211Geneva 20, Switzerland.

APPENDIX B. REFERENCES - INFORMATIVE

B1 Listed here are standards, handbooks and otherpublications which may provide useful information andbackground but are not considered essential. References inthis appendix are not considered part of the standard.

B1.1 ANSI/ARI Standard 210/240-1994, Unitary Air-Conditioning and Air-Source Heat Pump Equipment,1994, American National Standards Institute/Air-Conditioning and Refrigeration Institute, 11 West 42ndStreet, New York, NY 10036, U.S.A./4301 North FairfaxDrive, Suite 425, Arlington, VA 22203, U.S.A.

B1.2 ARI Standard 340/360-1993, Commercial andIndustrial Unitary Air-Conditioning and Heat PumpEquipment, 1993, Air-Conditioning and RefrigerationInstitute, 4301 North Fairfax Drive, Suite 425, Arlington,VA 22203, U.S.A.

B1.3 ARI Standard 420-1994, Unit Coolers forRefrigeration, 1994, Air-Conditioning and RefrigerationInstitute, 4301 North Fairfax Drive, Suite 425, Arlington,VA 22203, U.S.A.

B1.4 ARI Standard 440-1998, Room Fan Coils, 1998,Air-Conditioning and Refrigeration Institute, 4301 NorthFairfax Drive, Suite 425, Arlington, VA 22203, U.S.A.

B1.5 ARI Standard 840-1998, Unit Ventilators, 1998,Air-Conditioning and Refrigeration Institute, 4301 NorthFairfax Drive, Suite 425, Arlington, VA 22203, U.S.A.


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APPENDIX C. CRITERIA FOR PROPORTIONALITY -INFORMATIVE

C1 This appendix sets forth procedures and equations thatshould be used to determine the proportionalityrequirements of central station air handling units as definedby this standard.

C2 Basis of Proportionality.

C2.1 The following denotes the type of centralstation unit being rated:

C2.1.1 . t refers to a unit with tested performancerating.

C2.1.2. c refers to a unit with calculatedperformance rating.

C2.2 Proportional linear dimensions (See Figure C1)are determined using the following generic equation:

This ratio of the wheel diameters shall not be less than0.65.

C2.3 Proportional areas (See Figure C1) aredetermined using the following generic equation:

C3 Cabinet Proportionality.

C3.1 Linear dimensions C, D, E1, E2, G (See FigureC1).

C3.1.1

C3.1.2

C3.1.3

C3.1.4

C3.1.5

C3.1.6 The ratio of these distances shall beproportional within 1.5 percent.

C3.2 Areas.

C3.2.1 Fan Cabinet Air Inlet.

C3.2.2 Fan Cabinet Air Outlet.

C3.2.3 The ratio of these areas shall beproportional within 3 percent.

C4 Fan Proportionality.

C4.1 Proportional Linear Dimensions.

C4.1.1 Fan Wheel Width.

C4.1.2Fan Outlet Width.


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C4.1.3 Fan Housing Radii.

C4.1.4 The ratio of these radii shall beproportional within 1.5 percent.

C4.2 Proportional Areas.

C4.2.1 Fan Outlet Area.

C4.2.2 The ratio of these areas shall beproportional within 3 percent.


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S and T are inside dimensions of the cabinet outlet. R min and R max are measured from the center of the shaft.

Figure C1. Dimensions Used for Proportionality Equations

ANSI- ARI 430-99

Documents

ansiari standard

unit characteristics

rating requirements

fan speed

certification program

freedelivery aircoolers

air flow direction change

minimum data requirements