320-98

4301 NORTH FAIRFAX DRIVE ! ARLINGTON, VIRGINIA 22203

Standard 320

1998

STANDARD for

WATER-SOURCEHEAT PUMPS

Price $10.00 (M) $20.00 (NM) ©Copyright 1998, 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 tests conductedunder its standards will be non-hazardous or free from risk.

ARI CERTIFICATION PROGRAM PROVISIONS

Scope of the Certification Program

The certification program includes water-source heat pumps that are electrically driven, mechanicalcompression type systems as defined in the standard and included in this program.

Equipment Covered: This program applies only to water-source heat pumps, rated below 135,000Btu/h [40 kW] at ARI Standard Rating Conditions (Cooling).

Exclusion: This certification program does not apply to the rating and testing of individualassemblies, such as condensing units or coils, for separate use.

Certified Ratings

The following certification program ratings are verified by test:

1. Cooling Capacity, Btu/h [W]2. EER, Btu/w•h [W/W]3. Heating Capacity, Btu/h [W]4. COP, W/W

Note:

This standard supersedes ARI Standard 320-93.

TABLE OF CONTENTS

SECTION PAGE

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

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

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

Section 4. Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Section 5. Testing and Rating Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Section 6. Performance Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Section 7. Marking and Nameplate Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Section 8. Voluntary Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

TABLES

Table 1. Classification of Water-Source Heat Pumps . . . . . . . . . . . . . . . . . . . . . . . . . 2

Table 2. Minimum External Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

APPENDICES

Appendix A. References - Normative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Appendix B. References - Informative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

ARI STANDARD 320-1998

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WATER-SOURCE HEAT PUMPS

Section 1. Purpose

1.1 Purpose. The purpose of this standard is to establish Rating Heating Conditions.for water-source heat pumps: definitions and classifications;requirements for testing and rating; performancerequirements; marking and nameplate data; andconformance conditions.

1.1.1 This standard is intended for the guidance ofthe 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 factory-maderesidential, commercial and industrial water-source heatpumps, as defined in Section 3.

2.1.1 Energy Source. This standard applies only toelectrically-driven, mechanical compression typesystems.

2.1.2 Alternative Applications. Equipment designedfor rating under this standard may not be suitable foralternative applications covered in related ARIStandards 325 and 330.

2.2 Exclusions. This standard does not apply to individual rating conditions.assemblies for separate use.

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, Air-Conditioning and Refrigeration unless otherwise defined inthis section.

3.2 Coefficient of Performance (COP). A ratio of theheating capacity in watts [W], excluding supplementaryresistance heat, to the power input in watts [W] at any givenset of rating conditions expressed in watts/watt [W/W].(The international community uses the term EER asequivalent to cooling COP.)

3.2.1 Standard Coefficient of Performance. A ratioof the capacity to power input obtained at Standard

3.3 Cooling Capacity. The total heat-removal capacity isthe sum of the sensible and latent heat-removal capacitiesexpressed in Btu/h [W].

3.3.1 Sensible Heat. Heat associated with a changein dry-bulb temperature.

3.3.2 Latent Heat. The change of enthalpy during achange of state. It occurs with no change in dry-bulbtemperature.

3.4 Energy Efficiency Ratio (EER). A ratio of the coolingcapacity in Btu/h [W] to the power input in watts [W] at anygiven set of rating conditions, expressed in Btu/W•h [W/W].

3.4.1 Standard Energy Efficiency Ratio. A ratio ofthe capacity to power input values obtained at StandardRating Conditions.

3.5 Published Rating. A statement of the assigned valuesof those performance characteristics, under stated ratingconditions, 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 heat pump or published in specifications, advertisingor other literature controlled by the manufacturer, at stated

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

3.5.2 Application Rating. A rating based on testsperformed at application rating conditions (other thanStandard Rating Conditions).

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

3.6.1 Standard Rating Conditions. Rating conditionsused as the basis of comparison of performancecharacteristics.

3.7 “Shall,” “Should,” “Recommended” or “It IsRecommended.” “Shall,” “should,” “recommended” or “itis recommended” shall be interpreted as follows:


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Table 1. Classification of Water-SourceHeat Pumps

Types of Water-Source Heat Pumps

DesignationARIType Arrangement*

Single Package(Ducted)

HSP-W FAN COMPEVAP COND

Split System(Ducted)

HRCU-W FAN COMPEVAP COND

Single Package(Free Delivery)

HSP-W-O FAN COMPEVAP COND

Split System(Free Delivery)

HRCU-W-O FAN COMPEVAP COND

Denotes cooling mode function.*

3.7.1 Shall. Where “shall” or “shall not” is used fora provision specified, that provision is mandatory ifcompliance with the standard is claimed. 4.1 Classification. Normally, water-source heat pumps

3.7.2 Should, Recommended or It Is Recommended.“Should,” “recommended” or “it is recommended” isused to indicate provisions which are not mandatory butwhich are desirable as good practice.

3.8 Standard Air. Air weighing 0.075 lb/ft [1.2 kg/m3 3

which approximates dry air at 70EF [21.1EC] and at abarometric pressure of 29.92 inches of mercury [101.1 kPa].

3.9 Water-Source Heat Pump. A water-source heat pumpis typically one of multiple units using fluid circulated in acommon piping loop as a heat source/heat sink. Thetemperature of the loop fluid is usually mechanicallycontrolled within a moderate temperature range of 60EF to90EF [15.5E C to 32.2EC]. The heat pump consists of one ormore factory-made assemblies which normally include anindoor conditioning coil with air moving means,compressor(s) and refrigerant-to-water heat exchanger(s),including means to provide both cooling and heating orcooling only functions. When such equipment is providedin more than one assembly, the separated assemblies shall bedesigned to be used together, and the requirements of ratingoutlined in the standard are based upon the use of matchedassemblies.

3.9.1 Functions. Water-source heat pumps shallprovide the function of air-circulating and cooling andheating with controlled temperature, and may includethe functions of water heating, air-cleaning,dehumidifying or humidifying.

Models could be designated as “cooling only” units asan option of a water-source heat pump and need notinclude the heating function provided the following aremet:

a. The components of the air-conditioningrefrigerant system (cooling system) aresubstantially the same as the correspondingheat pump system.

b. Switches, thermostats and/or other controls ofelectrical components required for the reversecycle heating mode can be altered or deleted asrequired to provide cooling only.

c. All other chassis components, fans, motors,pumps, housings, etc., must be substantially thesame between both versions.

Section 4. Classification

within the scope of this standard may be classified as shownin Table 1.

Section 5. Testing and Rating Requirements

5.1 Standard Rating. Standard ratings shall be establishedat the Standard Rating Conditions specified in 5.1.3. Allstandard ratings shall be verified by tests conducted inaccordance with ASHRAE Standard 37, and with the testmethods and procedures as described in this standard exceptthat the total cooling and heating capacity shall be theaverage of the Air-Enthalpy Method and the Water CoilMethod.

Standard Ratings relating to cooling or heating capacitiesshall be net values, including the effects of circulating-fanheat, but not including supplementary heat. Standard InputRatings shall be the total power input to the compressor(s)and fan(s), plus controls and other items included as part ofthe model number(s).

5.1.1 Values of Standard Capacity Ratings. Theseratings shall be expressed in Btu/h [W] in multiples of100 Btu/h [10 W].

5.1.2 Values of Standard Energy Efficiency Ratio orCoefficients of Performance. Standard ratios of energyefficiency for cooling, whenever published shall beexpressed in multiples of the nearest 0.1 Btu/W•h[cooling COP in multiples of 0.1] standard coefficientsof performance for heating whenever published shall beexpressed in multiples of the nearest 0.1.


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5.1.3 Standard Rating Conditions. The conditionsof test for Standard Ratings shall include thefollowing:

5.1.3.1 Standard Rating Temperatures.

a. Cooling.

Air temperature entering indoor portion of unit............80EF [26.7EC] dry bulb 67EF [19.4EC] wet bulbAir temperature surrounding

unit.................80EF [26.7EC] dry bulbWater temperature entering

refrigerant-to-waterheat exchanger..............85EF [29.4EC]

Water temperature leavingrefrigerant-to-waterheat exchanger..............95EF [35.0EC]

b. Heating (not required for cooling onlymodels).

Air temperature entering indoor portion of unit............70EF [21.1EC] dry bulb 60EF [15.6EC] wet bulb, max.Air temperature surrounding

unit.................70EF [21.1EC] dry bulbWater temperature entering

refrigerant-to-waterheat exchanger..............70EF [21.1EC]

Water flow rate..............as determined inStandard RatingCooling Test

5.1.3.2 Electrical Conditions. Standard Ratingtests shall be performed at the nameplate ratedvoltage(s) and frequency.

For heat pumps with dual nameplate voltageratings, Standard Rating tests shall be performedat both voltages, or at the lower of the twovoltages, if only a single Standard Rating is to bepublished.

5.1.3.3 Indoor-Side Air Quantity. All StandardRatings shall be determined at an indoor-side airquantity, delivered against at least the minimumexternal resistance required by 5.1.3.5 as outlinedin Table 2. All air quantities shall be expressed ascfm [m /s] of Standard Air (density 0.075 lb per3

cu ft [1.2 kg/m ]).3

a. Heat pumps shall be rated at the indoor-side air quantity delivered whenoperating against the minimum externalresistance specified in 5.1.3.5 or at alower indoor-side air quantity, if sospecified by manufacturer.

Indoor-side air quantities as referred to hereinapply to the air quantity experienced when theunit is cooling and dehumidifying under theStandard Rating Cooling Conditions specified inthis section. This air quantity, except as noted in6.3, shall be employed in all other tests prescribedherein without regard to resulting external staticpressure, or if so specified by the manufacturer theair quantity employed in all of the tests shall bethat achieved at the external resistance employedin Standard Rating Cooling test.

5.1.3.4 Requirements for Separated Assemblies.All Standard Ratings for heat pumps in which theoutdoor section is separated from the indoorsection, as in Type HRCU (shown in Section 4),shall be determined with at least 25 ft. [7.62 m] ofinterconnection tubing on each line, of the sizerecommended by the manufacturer. Such heatpumps in which the interconnection tubing isfurnished as an integral part of the machine notrecommended for cutting to length shall be testedwith the complete length of tubing furnished, orwith 25 ft. [7.62 m] of tubing, whichever isgreater. The line sizes, insulation and details ofinstallation shall be in accordance with themanufacturer's published recommendations.

5.1.3.5 Minimum External Resistances. Indoorair-moving equipment intended for use with fieldinstalled duct systems shall be designed to operateagainst, and tested at not less than, the minimumexternal resistance shown in Table 2 whendelivering the rated capacity and air quantityspecified in 5.1.3.3. Indoor air-moving equipmentnot intended for use with field installed ductsystems shall be tested at 0 in. of H O [0 kPa]2

external pressure.

In interpreting this requirement, it is understoodthat the most restrictive filters, supplementaryheating coils and other equipment recommendedas optional parts of the heat pump be in place andthat the next external resistances specified inTable 2 above are available for the external ductsystem.


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Table 2. Minimum External Resistance

Standard CoolingCapacity Ratings

MinimumExternal

Resistance

Btu/h x 1000 [kw]

In.of

H O2 [kPa]

Up thru 28.929 thru 42.943 thru 70.9

71 thru 105.9106 thru 134.9135 thru 210.9211 thru 280.9281 thru 350.9351 thru 400.9401 thru 500.9501 and over

Up thru 8.48.5 thru 12.512.6 thru 20.720.8 thru 31.031.1 thru 39.539.6 thru 61.761.8 thru 82.2

82.3 thru 102.8102.9 thru 117.4117.5 thru 146.7146.8 and over

0.100.150.200.250.300.350.400.450.550.650.75

0.0250.0370.0500.0620.0750.0870.1000.1120.1370.1620.187

5.2 Part-Load Rating. Heat pumps which are capable ofcapacity control shall be rated at each step of capacityreduction provided by the heat pump and allowed by thecontrols.

5.2.1 Part-Load Rating Conditions. The conditionsof test for part-load ratings are the same as for theStandard Ratings (see 5.1) except for the following:

5.2.1.1 Part-Load Rating Temperatures(Cooling).

Air temperature entering indoor portionof unit..........................80EF [26.7EC] dry bulb

67EF [19.4EC] wet bulbWater temperature entering refrigerant-

to-water heat exchanger.............75EF [23.9EC]Water flow rate............as determined in Standard

Rating Cooling Test

5.2.1.2 Part-Load Rating Temperatures(Heating—not required for cooling only models).

Air temperature entering indoor portionof unit........................70EF [21.1EC] dry bulb

60EF [15.6EC] wet bulb max.Air temperature surrounding

unit...............................70EF [21.1EC] dry bulbWater temperature entering refrigerant-

to-water heat exchanger.............75EF [23.9EC]Water flow rate............as determined in Standard

Rating Cooling Test

5.2.1.3 The capacity reduction means may beadjusted to obtain the specified step of unloading.No manual adjustment of indoor air quantitiesfrom those of standard rating conditions shall bemade. Automatic adjustment of the quantities bysystem function, however, is permissible.

5.3 Application Ratings. Ratings at conditions ofair/water temperature or air/water quantity other than thosespecified in 5.1.3 and 5.2.1, may be published asapplication ratings, and shall be based on data determinedby the methods prescribed in 5.1.

5.4 Publication of Ratings. Wherever application ratingsare published or printed, they shall include, or beaccompanied by, the Standard Capacity Ratings plus thePart-Load Rating (where applicable), and theircorresponding power inputs, clearly designated as such,including a statement of the conditions at which the ratingsapply.

5.4.1 Capacity Designation. The capacitydesignation used in published specifications, literatureor advertising, controlled by the manufacturer, for heatpumps rated under this standard, are to be expressedonly in Btu/h [W] at the Standard Rating Conditionsspecified in 5.1.3 plus Part-Load Rating Conditionsspecified in 5.2.1 and in the terms described in 5.1.1through 5.1.2. Horsepower, tons or other units shallnot be used as capacity designations.

5.5 Tolerances. To comply with this standard publishedcooling capacity ratings, heating capacity ratings, ratios ofenergy efficiency for cooling and coefficients ofperformance for heating shall be based on data obtained inaccordance with the provisions of this section, and shall besuch that any production unit, when tested, will meet orexceed these ratings except for an allowance to covertesting and manufacturing variations: the amount ofallowance to be minus 5 percent.

Section 6. Performance Requirements

6.1 Performance Requirements. To comply with thisstandard, water-source heat pumps shall be designed andproduced in accordance with the provisions of this sectionin such a manner that any production unit will meet therequirements detailed herein.

6.2 Maximum Operating Conditions Test. Water-sourceheat pumps shall be designed and produced to pass thefollowing maximum operating conditions test with anindoor-side coil air quantity as determined under 5.1.3.3:


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6.2.1 Temperature Conditions. 6.2.2.4 Single phase dual voltage units whose

6.2.1.1 Cooling.

Air temperature surrounding unit...............95EF [35.0EC] dry bulbAir temperature entering indoor portion of unit...........95EF [35.0EC] dry bulb

71EF [21.7EC] wet bulb 6.2.3 Procedure.Water temperature entering refrigerant-to-water heat exchanger...............95EF [35EC]Water flow rate............maintained same as in 5.1.3.1

6.2.1.2 Heating (not required for cooling onlymodels).

Air temperature enteringindoor portionof unit..........80EF [26.7EC] dry bulb

Air temperature surroundingunit...............80EF [26.7EC] dry bulb

Water temperature enteringrefrigerant-to-waterheat exchanger............90EF [32.3EC]

Water flow rate............maintained sameas in 5.1.3.1

6.2.2 Voltages.

6.2.2.1 Tests shall be run at 90 percent and110 percent of the unit's nameplate rated voltageat the unit's service connection and at ratedfrequency, or at a lower than 90 percent minimumor a higher than 110 percent maximum voltage iflisted on the nameplate.

6.2.2.2 The power supplied to the heat pumpshall be adjusted just prior to the shut down period(see 6.2.3.2) so that the resulting voltage at theunit's service connection is 86 percent ofnameplate rated voltage when the compressor ison locked rotor. (For those dual voltage units sospecified on their specification sheets for aminimum voltage 5 percent below the lower ratedvoltage, this locked-rotor voltage setting shall be91 percent of the lower rated voltage.)

6.2.2.3 Within one minute after the heat pumphas resumed continuous operation (see 6.2.4.3),the voltage shall be restored to the values specifiedin 6.2.2.1.

lower voltage is 208V, which specify on theirspecification sheets a minimum voltage to beapplied at the unit service connection for themaximum operating conditions test, shall betested at the lower of this minimum voltage or198V in accordance with 6.2.2.1, 6.2.2.2 and6.2.2.3.

6.2.3.1 The heat pump shall be operated for twohours at the temperature conditions and voltage(s)specified.

6.2.3.2 All power to the heat pump shall be cutoff for a period sufficient to cause the compressorto stop (not to exceed five seconds) and thenrestored.

6.2.4 Requirements.

6.2.4.1 During both entire tests, the heat pumpshall operate without failure of any of its parts.

6.2.4.2 The heat pump shall operatecontinuously without interruption for any reasonfor the two-hour period preceding the powerinterruption.

6.2.4.3 The unit shall resume continuousoperation within two hours of restoration of powerand shall then operate continuously for one hour.Operation and resetting of safety devices prior toestablishment of continuous operation ispermitted.

6.3 Low-Temperature Operation Test (Cooling). Water-source heat pumps shall be designed and produced to passthe following low-temperature operation test whenoperating with initial air quantities as determined in 5.1.3.3and with controls and dampers set to produce the maximumtendency to frost or ice the evaporator, provided suchsettings are not contrary to the manufacturer's instructionsto the user:

6.3.1 Temperature Conditions.

Air temperature entering indoor portionof unit....................67EF [19.4EC] dry bulb


to-water heat exchanger.......65EF [18.3EC]Water flow rate..................... maintained same

as in 5.1.3.1


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6.3.2 Procedure. The test shall be continuous with 6.4.2 Procedure. After establishment of thethe unit on the cooling mode, for not less than four specified temperature conditions, the unit shall behours after establishment of the specified temperature operated continuously for a period of four hours.conditions. The unit will be permitted to operate underthe control of a limit device, if provided.

6.3.3 Requirements.

6.3.3.1 During the entire test, the heat pumpshall operate without damage to the equipment.

6.3.3.2 During the entire test, the air quantityshall not drop more than 25 percent from thatdetermined under the Standard Rating CoolingTest.

6.3.3.3 During the test, and during the ±1.0 percent of the reading for voltages.defrosting period after the completion of the test,all ice or meltage must be caught and removed bythe drain provisions. Section 7. Marking and Nameplate Data

6.3.3.4 For a dual voltage unit, unit shall 7.1 Nameplate Data. The nameplate shall display theoperate continuously at the lower voltage. manufacturer's name, model designation, and electrical

6.4 Insulation Efficiency Test (Cooling). Water-sourceheat pumps shall be designed and produced to pass thefollowing insulation efficiency test when operating with airquantities as determined in 5.1.3.3 with controls, fans,dampers and grilles set to produce the maximum tendencyto sweat, provided such settings are not contrary to themanufacturer's instructions to the user.

6.4.1 Temperature Conditions.

Air temperature entering andsurrounding indoorportion of unit.......80EF [26.7EC] dry bulb


to-water heat exchanger.......80EF [26.7EC]Water flow rate.....................maintained same

as in 5.1.3.1

6.4.3 Requirements.

6.4.3.1 During the test, no condensed watershall drop, run or blow off from the unit casing.

6.4.3.2 For a dual voltage unit, unit shalloperate continuously at the lower voltage.

6.5 Tolerances. The conditions for the tests outlined in6.2, 6.3 and 6.4 are average values subject to tolerances of±1.0EF [±0.6EC] for air wet bulb and dry bulbtemperatures, ±0.5EF [±0.3EC] for water temperatures and

characteristics.

Recommended nameplate voltages for 60 Hertz systemsshall include one or more of the equipment nameplatevoltage ratings shown in Table 1 of ARI Standard 110.Recommended nameplate voltages for 50 Hertz systemsshall include one or more of the utilization voltages shownin Table 1 of IEC Standard Publicaton 38.

Section 8. Voluntary Conformance

8.1 Conformance. While conformance with this standardis voluntary, conformance shall not be claimed or impliedfor products or equipment within its Purpose (Section 1) orScope (Section 2) unless such claims meet all of therequirements of the standard.


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APPENDIX A. REFERENCES - NORMATIVE

A1 Listed here are all standards, handbooks and other A1.3 ASHRAE Terminology of Heating, Ventilation,publications essential to the formation and implementation Air-Conditioning and Refrigerating, American Societyof the standards. All references in this appendix are of Heating, Refrigerating and Air-Conditioningconsidered as part of the standard. Engineers, Inc., 1791 Tullie Circle N.E., Atlanta, GA

A1.1 ARI Standard 110-97, Air-Conditioning andRefrigerating Equipment Nameplate Voltages, 1997, A1.4 IEC Standard Publication 38, IEC StandardAir-Conditioning and Refrigeration Institute, 4301 Voltages, 1983, International ElectrotechnicalNorth Fairfax Drive, Suite 425, Arlington, VA 22203, Commission, 3, rue de Varembe, P.O. Box 131, 1211U.S.A. Geneva 20, Switzerland.

A1.2 ASHRAE Standard 37-1988, Methods ofTesting Unitary Air-Conditioning and Heat PumpEquipment, 1988, American Society of Heating,Refrigerating and Air-Conditioning Engineers, Inc.,1791 Tullie Circle N.E., Atlanta, GA 30329, U.S.A.

30329, U.S.A.

APPENDIX B. REFERENCES - INFORMATIVE

B1. Listed here are standards, handbooks and other B1.2 ARI Standard 330-98, Ground-Source Closed-publications which may provide useful information and Loop Heat Pumps, 1998, Air-Conditioning andbackground but are not considered essential. References in Refrigeration Institute, 4301 North Fairfax Drive, Suitethis appendix are not considered part of the standard. 425, Arlington, VA 22203, U.S.A.

B1.1 ARI Standard 325-98, Ground Water-SourceHeat Pumps, 1998, Air-Conditioning and RefrigerationInstitute, 4301 North Fairfax Drive, Suite 425,Arlington, VA 22203, U.S.A.

320-98

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