.. 

1987 

STANDARD for 

,1I1.l'; 

• III • 

AIR-CONDITIONING 

& REFRIGERATION 

I NSmUTE 

C. J 

.OBSOLETE 

COMMERCIAL AND 

INDUSTRIAL 

UNITARY 

AIR-CONDITIONING 

CONDENSING UNITS 

I Standard 365 I 

1501 WILSON BOULEVARD. ARLINGTON, VIRGINIA 22209 
. ' 

SECTION 

RETURN TO 

KEH-UBRARY 

TCPC/E6-13 

T ABLE OF CONTEN I oJ 

PAGE 

1. Purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1 

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

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

4. Classification ............................................................................. 1 

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

6. Performance Requirements ................................................................. 5 

7. Safety Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 

8. Conformance ............................................................................. 5 

Appendix A "Method and Example of Calculating Integrated Part Load Valves (IPLV) ..................... 6 

Prtcen.oo 

~IIIU.S.A. 

NOTE: 

This standard supersedes ARI Standard 365-85 

.!! r.;; C COPYRIGHT 1987, by Air-Conditioning and Refrigeration Institute 

_ •• ,. Registered United States Patent and Trademark Office 
:~ 0 1\'\ to 

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OBSOlETE ('" -I 

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I 

-----------------~._;_---- AR I STAN DA R 0 365-87 

COMMERCIAL AND INDU TRIAL UNITARY 

AIR-CONDITIONING CONDENSING UNITS 

Section 1_ Purpose 

1.1 Purpose. The purpose of this standard is to establish for commercial and industrial air-conditioning condensing units: definitions and classifications; requirements for testing and rating; specifications, literature 

and advertising requirements, performance requirements; safety recommendations and conformance conditions. 

1.1.1 This standard is intended for guidance of the 

industry, including manufacturers, distributors, installers, contractors, and consumers. 

1.2 Review and Amendment. This standard-is subject to 

review and amendment as the art of the industry advances. 

Section 2. Scope 

2.1 Scope. This standard applies to factory-made commercial and industrial unitary air-conditioning condensing units defined in Section 3. 

2.1.1 Energy Source. This standard applies only to 

electrically-driven, mechanical compression type 

condensing units. 

2.2 Exclusions. This standard does not apply to condensing units with capacities less than 135,000 Btuh [40 

kW]. It also does not apply to the testing and rating of 

condensing units for refrigeration purposes, as defined 

in ARI Standard 520. 

Section 3. Definitions 

3.1 Commercial ~nd Industrial Unitary AirConditioning Condensing Unit. A commercial and industrial unitary air-conditioning condensing unit is a 

factory-made assembly of refrigerating components designed to compress and liquefy a specific refrigerant. It 

consists of one or more refrigerant compressors, refrigerant condensers, condenser fans and motors (where 

used) and factory-supplied accessories. 

3.2 Published Rating. A statement of the assigned 

values of those performance characteristics, under 

stated rating conditions, by which a unit may be chosen 

to fit its application. These values apply to all units of like 

nominal size and type (identification) produced by the 

same manufacturer. As used here in, the term "published rating" includes the rating of all performance 

characteristics shown on the air-conditioner components or published in specifications, advertising, or other 

literature controlled by the manufacturer, at stated rating conditions. - -

3.2.1 Standard Rating. _A rating based on tests 

performed at Standard Rating Conditions. 

3.2.2 Application Rating. A rating based on tests 

performed at application rating conditions (other 

than Standard Rating Conditions). 

3.3 Rating Conditions. Any set of operating conditionsunder which a single level of performance results, and 

which causes only that level of performance to occur. 

3.3.1 Sta';dard Rating Conditions. Rating conditions used as the basis of comparison of performance characteristics. 

3.4 Energy Efficiency Ratio (EER). A ratio calculated 

by dividing the condensing unit cooling capacity in 

thousands of Btu per hour (Mbh) by the condensing unit 

power input in kilowatts (kW) at Standard Rating Conditions, expressed as Btuh/Watt. 

3.5 Integrated Part Load Value (IP LV). A single number part load efficiency figure of merit calculated per 

the method described in 5.2.2. 

3.6 "Shall", "Should", "Recommended", or "It Is Recommended". "Shall", "should", "recommended", or 

"it is recommended" shall be interpreted as follows: 

3.6.1 Shall. Where "shall" or "shall not" is used 

for a provision specified, that provision is mandatory if compliance with the standard is claimed. 

3.6.2 Should, Recommended, or It Is Recommended. "Should", "recommended" or "it is recommended" is used to indicate provisions which 

are not mandatory but which are desirable as good 

practice. 

Section 4. Classification 

4.1 Classification. Normally, equipment covered within 

the scope of this standard may be classified as follows: 

Types of Commercial and Industrial 

Air-Conditioning Condensing Units 

ARI Heat 

Designation Type Rejection Arrangement 

Condensing RCU-A Air 

ICOMPI Unit RCU-E Evaporative COND 

RCU-W Water 

1 

PROPERTY OF U S GOVERNMENT 
A R I STA N DA R D 365-8 7 ------A/;~. -J/t....-----------------

Section 5. Testing and Rating Requirements 

5.1 Stalldard RCllillgs. Standard Ratings of condensing 

units shall be established at the Standard Rating Conditions shown in 5.1.3. All Standard Ratings shall be 

verified bv tests conducted in accordance with the 

ASH RAE' Standard MC'fhods of Testillg for Ratillg Positin! Displar:emelll Condensillg Ullits (American Society 

of Heating. Refrigerating. and Air-Conditioning Engineers. Inc. Standard 14-80) and with the test methods 

and procedures as described in this standard. An alternate method of verification may be used by tests conducted in accordance with ANSI/ASHRAE "37-1978 

Methods of Testillg for Ratillg Unitary Air-Conditioning 

and Heat Pump £quipmelll provided th~t the saturated 

suction temperature and actual suction"vapor temperature is determined from this procedure. 

Standard Cooling Capacities shall be, that obtained 

under Standard Rating Conditions. Pow~r input shall be 

the total power input to the compressor(s) and fanes) 

plus controls and other items included as part of the 

condensing unit. 

5.1.1 Values of Standard Capacity Ratings. These 

ratings shall be expressed only in terms of 

thousands of Btu per hour (Mbh) [kW] in multiples 

of 2 Mbh [0.6 kW] for units with standard ratings 

of 400 Mbh [117 kWJ and under. For units with 

standard ratings of over ~OO Mbh [117 kW]. the 

ratings shall be expressed in multiples of 5 Mbh 

[1.5 kWJ. 

5.1.2 Values of Standard Efficiency Ratings. Energy Efficiency Ratios (EER) in Btuhlwatt and 

Integrated Part Load Values (IPLV) shall be expressed in multiples to the nearest 0.1. 

5.1.3 Standard Ruting Conditions. The conditions 

of test for Standard Rating for condensing units 

shall include the following: 

5.1.3.1 Stalldard --- Rating Temperatures. Standard Capacity Ratings and corresponding power 

input shall be determined at the following temperature conditions as shown in Table 1. 

5.1.3.2 Single Number Rating. Where single 

number ratings are required the reported values shall be determined by averaging the results of the following tests from Table 1: 

For all units 

Refrigerant Entering condensing Unit 

Saturated suction temperature 50F [lO°C] and 

40F [4.4°C] 

Actual suction temperature 65F [18.3°C] and 

55F [12.8°C] 

Air-cooled and Evaporatively-cooled units 

Air entering and surrounding unit 

Water-cooled units 

95F [35°C] D.B. 

75F [23.9°C] W.B.· 

Entering water temperature 85F[29.4°C] 

Leaving water temperature 95F[35°C] 

5.1.3.3 Voltage and Frequency. Recommended nameplate voltages for 60 Hertz systems are one or more of the following utilization voltages: 200, 230, 460, 575. 

"Required for Evaporatively-cooled units. 

Table 1. Standard Rating Conditions 

Air- and Evaporatively-Cooled Condensing Units 

Air Entering and Surrounding Unit ( I) Refrigerant Entering Condensing Unit 

Dry Bulb (2) Wet Bulb Saturateu Suction Temp. Actual Suction Temp. 

F ·C F ·C F ·C F ·C 

95 35 75 23.9 50 10 6~ Ill.] 

95 35 75 23.9 40 4.'; 55 12.8 : 

HO 26.7 67 19.4 50 III 65 18.3 

80 26.7 67 19.4 40 -1 .4 . 55 12.8 

Water-Cooled Condensing Units .. 

Water Temperature 

Entering Leaving 

F ·C F ·C 

85 29.4 95 35 51l 10 65 18.3 

H5 29.4 95 35 40 4.4 55 12.8 

75 23.9 same flow rate SO 10 65 18.3 

75 23.9 as above 40 4.4 55 12.8 

NOTES: (I) The liquid temperature and pressure leaving the condensing unit shall be reponed by the manufacturer 

in his ratings. 

(2) Required for evaporatively-cooled condensing units only. 

2 
----------------------------------------------__ ARI 

Standard Rating tests shall be performed at the 

nameplate rated voltage and frequency. 

For condensing units with dual nameplate voltage ratings. Standard Rating tests shall be performed at both voltages. or at the lower of the 

two voltages, if only a single Standard Rating is 

to be published. 

5.1.3.4 Condenser Air Quantity. All Standard 

Ratings for condensing u.nits sha!l be d~termined at the condenser aIr quantIty specIfied 

by the manufacturer where th~ fa~ dz:ive is adjustable; or where the fan dnve IS dIrect-connected, they shall be determined at the condensing unit when operated with all of the 

resistance elements as associated with inlet louvres and any duct work and attachments considered by the manufacturer as normal installation practice. Once established, the 

condenser air circuit of the condensing unit 

shall remain unchanged throughout all tests 

prescribed herein, except as altered by automatic controls. 

5.2 Part-Load Rating. Condensing units which are capable of capacity reduction shall be rated at 100% and 

at each step of capcity reduction provided by the condensing unit as published by the manufacturer. These 

rating points shall be used to calculate the IPL V (see 

5.2.2). 

5.2.1 Part Load Rating Conditions. The conditions of test for part load rating are the same for 

the Standard Ratings (See 5.1) except for the following: 

5.2.1.1 Part Load Rating Temperatures. 

For all units 

Refrigerant Entering Condensing Unit 

Saturated suction temperature 50F[100] 

Actual suction temperature 65F[18.3°C] 

For air-cooled units 

Air temperature entering and surrounding unit 

of unit. ............... 80 F [26.7°C] dry blub 

(and 67 F [19.4°C] wet bulb when condensate 

is rejected into the air stream) 

For evaporatively-cooled units 

Air temperature entering and surrounding unit 

of unit ................ 80 F [26.7°C] dry bulb 

67 F [19.4°C] wet bulb 

For water-cooled units 

Water temperature entering 

condenser .................. ~ .... 75F [23.9°C] 

Water flow rate (Same as Standard Rating 

Conditions) 

5.2.1.2 The capacity reduction means may be 

adjusted to obtain the specified step of unloading. No manual adjustment of condenser air' 

quantities from those of the Standard Rating 

Conditions shall be made. However. automatic 

adjustment of condenser air quantities by condensing unit function is permissible. 

5.2.2 Integrated Part Load Value (IPLV). For. 

equipment covered by this standard. the IPL V (in 

EER) shall be calculated as follows: 

a. Determine the capacity and EER at the conditions specified in 5.2 

b. Determine the part-load factor (PLF) from 

Figure 1 "Part-Load Factor Curve" at each 

rating point (see Example in Appendix B). 

c. Use the following equation to calculate 

IPLV: 

(

EER + EER.) IPL V = (PLF1 - PLF2) 1 2 -

(

EER2 + EERJ) + (PLF1 - PLFJ ) 2 

+ ..... . .. . 

(

EERn _ 1 + EERn) + (PLFn _ 1 - PLFn ) 2 

+ (PLF,,)(EER,,) 

where: PLF = Part-Load Factor determined from 

Figure 1 

n = Total number of capacity steps 

Subscript 1 = 100% capacity and EER at 

part-load rating conditions 

Subscript 2; 3 etc. = specific capacity and 

EER at part-load 

steps per 5.2 

5.3 Publication of Ratings. Wherever application ratings are published or printed, they s~all include, or ~e 

accompanied by, the Standard RatlOg clearly ~c:slgnated as such, including a statement of the condItIons 

at which the ratings apply. 

5.3.1 Capacity Designations. The capacity. designations used in published specifications, literature or advertising, controlled by the manufacturer shall be expressed only in Mbh [kW] at the 

Standard Rating Conditions specified in 5.1.3 and. 

in the terms described in 5.1.1 and 5.1.2 Horsepower, tons or other units shall not be used as 

capacity designations. 

5.4 Tolerances. To comply with this stand~rd, published cooling capacity ratings and energy effiCIency r~tings shall be based on data obtained in accorda~ce W1~h 

this section. and shall be such that any prod,!ctlon urnt. 

when tested. will meet or exceed these ratIngs exc~pt 

for an allowance to cover testing and man'!factunng 

variations; the amount of allowance to be mmus 5 per 

cent. 

3 
~ , 

ARI STANDARD 365-87 ; 

U 

PART LOAD FACTOR CURVE 

1.0 

,/ I--""'" 

0.9 / 

/ 

0.8 

I 

0.7 I 

I 

L2 0.6 

, -l 

a.. J a:: 

f2 0.5 I ~ I u: 

0 I 0.4 

~ -l I ~ 

a:: 0.3 / ~ 1/ 

0.2 j 

'/ 

0.1 / ~ V 

-' V 

0 

0 20 40 60 80 100 

PERCENT OF FULL-LOAD CAPACITY AT 

PART-LOAD CONDITIONS 

Note: Curve is Based on Following Equation: 

PLF = AO + (AI x Q) + (A2 X Q2) + (A3 X Q3) + (A4 X Q4) + (AS X Q5) + (A6 X Q6) 

where: PLF = Part-Load Factor 

Q = Percent of full-load capacity at part-load rating 

conditions. 

AO = -0.12773917 X 10-6 

Al = -0.27648713 x 10-3 

. A2 = 0.50672449 x 10-3 

A3 = -0.25966636 X 10- 4 

A4 = 0.69875354 x 10-6 

. AS = -0.76859712 X 10- 8 

A6 = 0.28918272 x 10- 10 

FIGURE 1 

4 
________________________ ARI STANDARD 365-87 

Section 6. Performance Requirements 

6.1 Performance Requirements. To comply with this 

standard, commercial and industrial unitary air~ 

conditioning condensing units shall be designed and 

produced in accordance with the provisions of this section in such a manner that any production unit will meet 

the appropriate requirements detailed herein. 

6.2 Maximum Operating Conditions Test. Commercial 

and industrial unitary air-conditioning condensing units 

shall be designed and produced to pass the following 

maximum operating conditions tests. For multi-capacity 

units. this test shall be conducted with unit control set for 

maximum capacity. 

6.2.1 Temperature Conditions. 

For aI/units 

Air temperature surrounding unit 115 F [46.1°C] 

dry bulb· 

Refrigerant Entering Condensing Unit 

Saturated suction temperature ... 50 F [1 DoC] 

Actual suction temperature .... 65 F [IS.3°C] 

For water-cooled units 

Water temperature entering 

condenser ................... 90 F [32.2°C] 

Water temperature leaving 

condenser .................. 100 F [37.8°C] 

For air-cooled units 

Outside air 

temperature ........ 115 F [46. 1°C] dry bulb 

(and 75 F [23.9°C] wet bulb when condensate is 

rejected to the condenser air stream) at the 

standard condenser air quantity specified and 

stated by the manufacturer. 

For evaporatively~cooled units 

Outside air 

temperature ........ 100 F [37.S0C) dry bulb 

SO F [26.7°C] wet bulb 

Make-up water temperature . . ... 90 F [32.3°C] 

6.2.2 Voltages. 

6.2.2.1 Tests shall be run at 90 per cent and 110 

per cent of the unit's nameplate rated voltage at 

·For units or portions thereor intended to be installed only indoors. 

this temperature may be reduced to 9S F [3soq dry bulb. 

the unit's service connection and at rated frequency. or at a lower than 90 per cent minimum 

or a higher than 110 per cent maximum voltage. 

if listed on the nameplate. 

6.2.3 Procedure. 

6.2.3.1 The condensing unit shall be operated 

continuously for two hours at. t.he temperature 

conditions and voltage(s) specified. 

6.2.3.2 All power to the condensing unit shall 

be cut off for a period sufficient to cause the 

compressor to stop (not to exceed five seconds) 

and then restored. 

6.2.4 Requiremellls. 

6.2.4.1 During both entire tests, the condensing 

unit shall operate without failure of any of its 

parts. 

6.2.4.2 The unit shall resume continuous operation within one hour of restoration of power 

and shall then operate continuously for one 

hour. Operation and resetting of safety devices 

prior to establishment of continuous operation is 

permitted. 

6.2.4.3 Units with water-cooled condensers 

shall be capable of operation under these 

maximum conditions at a water-pressure drop 

not to exceed 15 psi [103.4 kPa], measured 

across the unit. 

6.3 Tolerances. The conditions for the tests outlined in 

6.2 are average values subject to tolerances of :t 1.0 F 

[:to.56°C] for air wet~bulb and dry-bulb temperature, 

and :t 1.0 per cent of the reading for voltages. 

Section 7. Safety Recommendations 

7.1 Safety- It is strongly recommended that the product be designed, constructed, assembled and installed 

in accordance with nationally recognized safety stan~ 

dards and codes, appropriate for the product covered 

by this standard. 

Section 8. Conformance 

8.1 Conformance. While conformance with this stan~ 

dard is voluntary, conformance shall not be claimed or 

implied for products or equipment within its Purpose 

(Section 1) or Scope (Section 2) unless such claims meet 

all of the requirements of the Standard. 

5 
ARI STANDARD 365-87 ________________________________________________ _ 

APPENDIX A 

METHOD AND EXAMPLE OF 

CALCULATING INTEGRATED PART LOAD VALUES 

(IPLV) 

Section A1. Purpose and Scope 

Al.I Purpose. 

A.I.I.I This appendix shows example calculations 

for determining Integrated Part Load Values 

(IPLV). 

AI.2 Scope. 

A.I.2.1 This appendix is for equipment covered 

by this standard. 

Section A3. Calculation Example for a Four 

Capacity Step System 

A3.1 Unit Performance Data & Sample Calculation. 

A3.1.1 Assume equipment has four capacity steps 

as follows: 

• 100% (full load) 

• 7S% of full load 

• SO% of full load' 

• 25% of full load 

A3.1.2 Obtain part load factors from Figure 1 (see 

Figure Al Example). 

Section A2. Equations and Definitions of Terms 

,Al.I General Equation. 

A3.1.3 Obtain EER at each capacity step per S.2. 

A3.1.4 Calculate IPL V using the general equation 

with: 

n=4 

PLF1 = 1.0 

PLF2 = 0.9 

PLF3 = 0.4 

PLF4 = 0.1 

EERI = 8.9 

EER2 = 7.7 

EER3 = 7.1 

EER4 = S.O IPLV = (PLF1 - PLF2

) (EERI ; EER2) 

+ (PLF2 - PLFJ

) (EER2 ; EERJ) 

+ ........ . 

+ (PLF - PLF) (EERn _ 1 + EERn) n-l n 2 

+ (PLFn)(EERn) 

, Where: PLF = Part-Load Factor determined from 

Figure 1 

6 

n = Total number of capacity steps 

Subscript 1 = 100% capacity and EER at 

part-load rating conditions 

Subscript 2; 3, etc. = specific capacity steps 

per S.2. 

Enter the above values in the general equation, (A2.1). 

IPLV = (1.0_0.9)(8.9 ; 7.7) 

+ (0.9-0.4)e.7 ; 7.1) 

)(7.1 +S.O) + (0.4-0.1 2 + (0.1 xS.O) 

= (0.1 x 8.3) + (O.S x 7.4) 

+ (0.3 x 6.0) + 0.5 

= 0.83 + 3.70 + 1.80 + 0.5 

IPLV = 6.8 

To further illustrate the calculation process see Figure A2 Example. 
________________________ ARI STANDARD 365-87 

1.0 

0.9 

0.8 

0.7 

LL 

...J 0.6 ~ 

a: 

~ 0.5 

u.: ~ 

CJ 0.4 

C5 

...J 

~ 0.3 

~ 

0.2 

0.1 

0 ~ 

0 

PART LOAD FACTOR CURVE 

- - ./ 

/ 

, ... I 

/ 

I 

I 

I 

I 

I 

I 

'I - j 

/ 

/ 

J 

/ 

/ ~ ~ 

;/ ~, 

20 40 60 80 

PERCENT OF FULL-LOAD CAPACITY AT 

PART-LOAD CONDITIONS 

".,-

100 

Note: Curve is Based on Following Equation: 

PLF = AO + (AI xQ)+(A2x Q2)+ (A3x Q3)+(A4x Q4)+(A5XQS)+(A6xQ6) 

where: PLF = Part-Load Factor 

Q = Percent of full-load capacity at part-load rating 

conditions. 

AO = -0.12773917 X 10- 6 

Al = - 0.27648713 X 10-3 

A2 == 0.50672449 x 10-3 

A3 = -0.25966636 x 10-"' 

A4 = 0.69875354 x 10- 6 

A5 = -0.76859712 x 10- 8 

A6 = 0.28918272 x 10- 10 

FIGURE A1 EXAMPLE 

7 
ARI STANDARD 365-87 _______________________ _ 

FIGURE A-2 EXAMPLE 

IPLV CALCULATION 

Using information from A3.1.i; A3.1.2 and A3.1.3 

Capacity Mfrs. Net % Full PLP Mfrs.Part Avg. Part PLFDiff. 

Step Cap. (Tons) Load Cap.2 LoadEER LoadEER 

(For R Only) 

1 50.0 100% 1.0 8.!r 

= 8.3 (1.0-0.9)=0.1 

2 37.5 75% 0.9 7.7 

= 7.4 (0.9-0.4) =0.5 

3 25.0 50% 0.4 7.1 

= 6.0 (0.4-0.1) =0.3 

4 12.5 25% 0.1 S.O 

= 5.01 (0.1-0.0)=0.1 

- 0% 0.0 -

NOTES 

Avg. EER x PLF Diff. = 

8.3 x 0.1 = 

7.4 x 0.5 = 

6.0 x 0.3 = 

5.01 x 0.1 = 

Single number IPL V 

"Rounded to 

IFor the range between 0% capacity and the last capacity step, use EER of the last capacity step for the average EER. 

2"Jbe 100% capacity and EER are to be determined at the part-load rating conditions. 

3Part-Ioad factor from Figure AI. 

8 

Weighted 

Avg. 

0.83 

3.70 

1.80 

0.50 

6.83" 

'6.8 

•