OBSOLETE

C.’

1985

TO

KEHI

TCPCIRM 0 AREA

STANDARD for

GROUND

WATER-SOURCE

NEAT PUMPS

I Standard 325

AIR-CONDITIONING AND

1501 WILSON BOULEVARD

REFRIGERATION INSTITUTE

. ARLINGTON, VIRGINIA 22209

I I’.j) L..’
OBSOLETE

TC I

TABLE OF CONTENTS

PART 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. Safety Recominendation 6

Section 8. Conformance 6

PROPERTY OF U.S. GOVERNE’ T
ARI STANDARD 325-85

GROUND WATER-SOURCE HEAT PUMPS

Section 1. Purpose

1.1 Purpose. The purpose of this standard is to estab

lish, for ground water-source heat pumps: definitions

and classification; requirements for testing and rating;

specifications, literature and advertising requirements;

performance requirements; safety requirements; and

conformance conditions.

1.1.1 This standard is intended for the guidance of

the industry, including manufacturers, distributors,

consultants, contractors, and consumers

1.2 Review and Amendment. This standard is subject to

review and amendment as the art of the industry ad

vances.

Section 2. Scope

2.1 Scope. This standard applies to factory-made resi

dential, commercial, and industrial ground water-source

heat pumps, as defined in 3.1.

2.1.1 Energy Source. This standard applies only to

electrically-driven, mechanical compression type

systems.

2.2 Exclusions. This standard does not apply to the

rating and testing of individual assemblies for separate

use.

2.2.1 This standard does not apply to water-source

heat pumps as defined in ART Standard 320.

Section 3. Definitions

3.1 Ground Water-Source Heat Pump. A ground

water-source heat pump consists of one or more

factory-made assemblies which normally include an in

door conditioning coil with air moving means, compres

sor(s) and refrigerant-to-water heat exchanger(s), in

cluding means to provide a heating function and may

include a cooling function. When such equipment is

provided in more than one assembly, the separated as

semblies shall be designed to be used together, and the

requirements ofrating outlined in the standard are based

upon the use of matched assemblies.

3.1.1 Functions. Ground water-source heat pumps

shall provide the function of heating with controlled

temperature, and may include the functions of aircooling, air-circulating, air-cleaning, dehumidifying

or humidifying.

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 oflike

nominal size and type (identification) produced by the

same manufacturer. As used herein, the term “published

rating” includes the rating of all performance charac

teristics shown on the heat pump or published in specifi

cations, advertising, or other literature controlled by the

manufacturer, at stated rating conditions.

3.2.1 Standard Rating. A rating based on tests per

formed 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 conditions

under which a single level of performance results, and

which causes only that level of performance to occur.

3.3.1 Standard Rating Conditions. Rating condi

tions used as the basis of comparison of perfor

mance characteristics.

3.4 Energy Efficiency Ratio (EER). A ratio calculated

by dividing the cooling capacity in Btuh by the power

input in watts at any given set of rating conditions, ex

pressed in Btuh per watt (Btuh/watt).

3.4.1 Standard Energy Efficiency Ratio. A ratio

calculated from the capacity and power input values

obtained at Standard Rating Conditions.

3.5 Coefficient of Performance (COP). A ratio calcu

lated by dividing the total heating capacity provided by

the refrigeration system including circulating fan heat

but excluding supplementary resistance heat, (Btuh) by

the total electrical input (watts) x 3.412. [A ratio calcu

lated for both cooling and heating capacities by dividing

capacity in watts by power input in watts.]

3.5.1 Standard Coefficient ofPerformance. A ratio

calculated from the capacity and power input ob

tained in accordance with 3.5 at Standard Rating

Heating Conditions.

3.6 “Shall”, “Should”, “Recommended”, or “It is Rec

ommended”. “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 manda

tory if compliance with the standard is claimed.

3.6.2 Should, Recommended, or It is Recom

mended. “Should”, “recommended”, or “it is rec

ommended” is used to indicate provisions which are

not mandatory but which are desirable as good

practice.

1
ARI STANDARD 325-85.

Section 4. Classification

4.1 Classification. Normally, ground water-source heat

pumps within the scope ofthis standard may be classified

as shown in Table 1.

Section 5. Testing and Rating Requirements

5.1 Standard Rating. Standard ratings shall be estab

lished at the Standard Rating Conditions specified in

5.1.4. All standard ratings shall be verified by tests con

ducted in accordance with the ASHRAE Standard

Methods ofTesting for Rating Unitary Air-Conditioning

and Heat Pump Equipment (American Society. of Heat

ing, Refrigerating and Air-Conditioning Engineers, Inc.

Standard 37-78), and with the test methods and proce

dures as described in this standard.

Standard Ratings relating to cooling or heating

capacities shall be net values, including the effects of

circulating-fan heat, but not including supplementary

heat. Power input shall be the total power input to the

compressor(s) and fan(s), plus controls and other items

included as part of the model number(s).

Standard Ratings of units which do not have indoor

air-circulating fans furnished as part of the model, i.e.,

split system with indoor coil alone (see Table 1), shall be

established by subtracting from the total cooling capac

ity 1,250 Btuh/1000 cfm [0.78 watts perils], and by

adding the same amount to the heating capacity. Total

power input for both heating and cooling shall be in

creased by 365 watts/1000 cfm [0.78 watts per Us] of

indoor air handled.

5.1.1 Values of Standard Capacity Ratings. These

ratings shall be expressed only in terms of Btu per

hour (Btuh) [watts] in multiples of:

Capacities

(Btuh) [W]

Less than 20,000 [5,9001

20,000-37,800 [5,900-11,000]

38,000-64,500 [11,100-18,900]

65,000 and above [19,000

and above]

5.1.2 Values ofPressure Drop Ratings. Water flow

rate(s) and pressure drop(s) shall be determined at

each Standard Rating Condition specified in 5.1.4.

Water pressure drop through the unit for the rated

standard flow rate(s) shall be expressed in multiples

of 0.5 pounds per sq in (psi [3.5 kPa]. Waterfiow

rate(s) shall be expressed in gallons per minute [L’s]

in multiples of 0.1 gpm to 10 gpm and 0.5 gpm for

over 10 gpm [0.01 Us tà I Us and 0.05 Us over 1

Us]. Units supplied with water control valve shall be

tested with the valve wide open.

5.1.3 Values ofStandard Energy Efficiency Ratios

or Coefficients of Performance. Standard ratios of

energy efficiency for cooling, whenever published,

shall be expressed in multiples of the nearest 0.1

Btuhlwatt [cooling COP in multiples of 0.11; stan

dard coefficients of performance for heating,

whenever published, shall be expressed in multiples

of the nearest 0.1.

In calculating EER’s or COP’s, a penalty for the

water pump effect shall be added to the measured

power input and determined as follows:

PP =WF [(PPB x P) + 65)

where PP = total pumping penalty, in watts [‘NJ

WF = water flow rate, in gallons per minute

[L/s]

PPB = basic pumping penalty (Table 2), in

watts/gpm per .P in psi [watts/(Us)

per P in kPa]

= unit water pressure drop, in psi [kPa]

65 [1030] = constant, in watts per gpm

[watts per L/s] based on 50

ft [15.24 m] external head

Example: At rated flow of 10 gpm [0.631 Us],

from Table 2

PPB = 2.69 watts/gpm per P in psi

[watts/(L/s) per P in kPa]

With water coil pressure drop = 10 psi

[68.9 kPa]

PP 10 [(2.69 x 10) + 65] = 919

watts [919 watts]

5.1.4 Standard Rating Conditions. The conditions

of test for Standard Ratings shall include the follow

ing:

Multiples

(Btuh) [W]

100 [30]

200 [60]

500 [160]

1000 [300]

.

Table 1. Classification of Ground

Water-Source Heat Pumps

Types of Ground Water.Source Heat Pumps

+ARI Type

Designation Heating Heating *Arrangement

and Cooling Only

Single Package HSP.GW HOSP-GW FAN COMP1

EVAP CONDI

Split System HRCU- HORCU- FAN COMP

• GW-CB GW-CB IEVAP COND

Split System with HRCU- HORCU- COMP

No Indoor Fan GW-C GW-C IEVAPI COND

+A suffix of “-O”following any of the above classifications indicates

equipment not intended for use with field-installed duct systems (See

5.1.4.5). -

Denotes cooling mode function.

S

2
ARt STANDARD 325-85

Table 2. Basic Pumping Penalty PPB vs. WF

WF

(Watts/gpm [ Watts/(LIs)

(gallons per per P per

minute) (Usl in psi) in kPaJ

1 - 4.0 0.063 - 0.252 5.00 11.50

4.1 - 7.9 0.258 - 0.498 3.88 8.92

8.0- 12.9 0.504 - 0.750 2.69 6.19

12.0 - 15.9 0.757 - 1.002 2.32 5.34

16.0- 19.9 1.010- 1.254 2.14 4.92

20.0 and above 1.262 and above 2.02 4.65

5.1.4.1 Standard Rating Temperatures.

a. Cooling (High Temperature) (Not required

for heating-only units)

Air temperature entering indoor portion of

unit 80F[26.7°Cj dry bulb,

67F[19.4°C] wet bulb

Air temperature surrounding

unit 80F[26.7°CJ dry bulb

Water temperature entering refrigerant-towater heat exchanger 70F[21.1°C}

Water flow rate as specified

by manufacturer

b. Cooling (Low Temperature) (Not required

for heating-only units)

Air temperature entering indoor portion of

unit 80F[26.7°CJ dry bulb,

67F[19.4°C] wet bulb

Air temperature surrounding

unit 80F[26.7°C] dry bulb

Water temperature entering refrigerant-towater heat exchanger 50F[10°CJ

Water flow rate as specified

by manufacturer

c. Heating (High Temperature)

Air temperature entering indoor portion of

unit 70F[21.1°CJ dry bulb,

60F[15.6°C] wet bulb, max.

Air temperature surrounding

unit 70F[21.1°Cj dry bulb

Water temperature entering refrigerant-towater heat exchanger 70F[21.1°C}

Water. flow rate as specified

by manufacturer

d. Heating (Low Temperature)

Air temperature entering indoor portion of

unit 70F[21.1°Cj dry bulb,

60F{15.6°C] wet bulb, max.

Air temperature surrounding

unit 70F[21.1°Cj dry bulb

Water temperature entering refrigerant-towater heat exchanger 50F[10°Cj

Water flow rate as specified

by manufacturer

5.1.4.2 Electrical Conditions. Recommended

nameplate voltages for 60 Hertz systems are one

or more of the utilization voltages shown in Table

1 of ARI Standard 110 for Air-Conditioning and

Refrigerating Equipment Nameplate Voltages.

Standard Rating tests shall be performed at the

nameplate rated voltage(s) and frequency.

For heat pumps with dual nameplate voltage ra

tings, Standard Rating Tests shall be performed

at both voltages, or at the lower of the two vol

tages, if only a single Standard Rating is to be

published.

5.1.4.3 Indoor-Side Air Quantity. All Standard

Ratings shall be determined at an indoor-side air

quantity, delivered against at least the minimum

external resistance required by 5.1.4.5, as out

lined below. All air quantities shall be expressed

as cfm [L/sJ of standard air (density 0.075 lb per

cu ft [1.2 kg!m 31).

a. Heat pumps shall be rated at the indoor-side

air quantity delivered when operating against

the minimum external resistance specified in

5.1.4.5 or at a lower indoor-side air quantity,

if so specified by manufacturer.

b. Heat pumps which do not incorporate an in

door fan, but are rated in combination with a

device employing a fan shall be rated as de

scribed under a. above. For heat pumps of this

class which are rated for general use to be

applied to a variety of heating plants, the in

door-side air quantity shall be as specified by

the manufacturer in his standard ratings, or

the air quantity obtained through the indoor

coil assembly when the pressure drop across

the indoor coil assembly and the recom

mended enclosures and attachment means is

not greater than 0.30 inches of water [74.7

Pa], whichever is less.

Indoor-side air quantities as referred to herein

apply to the air quantity experienced when the

unit is cooling and dehumidifying under the Stan

dard High Temperature Rating Cooling Condi

tions specified in this section. Heating-only units

shall use the air quantity experienced when the

unit is operating under the Standard High Tern

perature Heating’ Rating Conditions. This air

quantity, except as noted in 6.3, shall be em

ployed in all other tests prescribed herein without

regard to resulting external static pressure.

5.1.4.4 Requirements for Separated Assemblies.

All Standard Ratings for heat pumps in which the

outdoor section is separated from the indoor sec

tion, as in Type HRCU (shown in Section 4), shall

be determined with at least 25 feet [7.62 nil of

3
ARI STANDARD 325-85.

interconnection tubing on each line, of the size

recommended by the manufacturer. Such heat

pumps in which the interconnection tubing is fur

nished as an integral part of the machine not

recommended for cutting to length shall be tested

with the complete length of tubing furnished, or

with 25 feet [7.62 m] of tubing, whichever is

greater. The line sizes, insulation, and details of

installation shall be in accordance with the manu

facturer’s published recommendations.

5.1.4.5 Minimum External Resistances. Indoor

air-moving equipment intended for use with field

installed duct systems shall be designed to oper

ate against, and tested at not less than, the

minimum external resistance shown in Table 3

when delivering the rated capacity and air quan

tity specified in 5.1.4.3. Indoor air-moving

equipment not intended for use with field in

stalled duct systems shall be tested at 0 in. water

[0 Pa] external pressure.

In interpreting this requirement, it is understood

that the most restrictive filters, supplementary

heating coils, and other equipment recom

mended as optional parts of the heat pump be in

place and that the net external resistances

specified above are available for the external duct

system.

5.2 Part-Load Rating. Heat pumps which are capable of

capacity control shall be rated at each step of capacity

reduction provided by the heat pump, and allowed by

the controls.

5.2.1 Part-Load Rating Conditions (Cooling and

Heating). The conditions of test for part-load rat

ings are the same as for the Standard Ratings (see

5.1). The capacity reduction means may be ad

justed to obtain the specified step of unloading.

Automatic adjustment of water flow rate by sys

tern function is permissible.

5.3 Application Ratings. Ratings at conditions of air or

water temperature or air or water quantity other than

those specified in 5.1.4 and 5.2.1, may be published as

application ratings, and shall be based on data deter

mined by the methods prescribed in 5.1.

5.4 Publication of Ratings. Wherever application ra

tings are published or printed, they shall include, or be

accompanied by, the Standard Capacity Ratings and

their Standard Energy Efficiency Ratios or Coefficients

of Performance, clearly designated as such, including a

statement of the conditions at which the ratings apply.

5.4.1 Capacity Designation. The capacity designa

tion used in published specifications, literature or

advertising, controlled by the manufacturer, for

heat pumps rated under this standard, are to be

Table 3. Minimum External Resistance

Minimum

External

Standard Cooling Capacity Ratings Resistance

(Inches of

(Thousands of Btuh) [kWJ Water) [Pa]

Up thru 28.8 Up thru 8.4 0.10 24.9

29 thru 42.5 8.5 thru 12.5 0.15 37.4

43 thru 70 12.6 thru 20.5 0.20 49.8

71 thru 105 20.8 thru 30.8 0.25 62.3

106 thru 134 31.1 thru 39.3 0.30 74.7

135 thru 210 39.6 thru 61.6 0.35 87.2

211 thru 280 61.7 thru 82.1 0.40 99.6

281 thru 350 82.2 thru 102.6 0.45 112.1

351 thru 400 102.7 thru 117.2 0.55 137.0

401 thru 500 1 17.3 thru 146.6 0.65 161.9

501 and over 146.7 and over 0.75 186.8

expressed only in Btuh [watts] at the Standard Ra

ting Conditions specified in 5.1.4 and in the terms

described in 5.1.1 through 5.1.3. Horsepower, tons

or other units shall not be used as capacity designa

tions.

5.5 Tolerances. To comply with this standard, pub

lished cooling capacity ratings, heating capacity ratings,

ratios of energy efficiency for cooling, and coefficients of

performance for heating, shall be based on data obtained

in accordance with the provisions of this section, and

shall be such that any production unit, when tested, will

meet or exceed these ratings except for an allowance to

cover testing variations; the amount of allowance to be

minus 5 percent.

Section 6. Performance Requirements

6.1 Performance Requirements. To comply with this

standard, ground water-source heat pumps shall be de

signed and produced in accordance with the provisions

of this section in such a manner that any production unit

will meet the requirements detailed herein.

6.2 Maximum Operating Conditions Test. Ground

water-source heat pumps shall be designed and pro

duced to pass the following maximum operating condi

tions test with an indoor side coil air quantity as deter

mined under 5.1.4.3:

6.2.1 Temperature Conditions.

6.2.1.1 Cooling (Not required for heating-only

units)

Air temperature surrounding

unit 80 F [26.7°C] dry bulb

Air temperature entering indoor portion

of unit 80 F [26.7°C] dry bulb,

67 F [19.4°C] wet bulb

Water temperature entering refrigerant

to-water heat exchanger 75 F [23.9°C]

0

I

C
ARI STANDARD 325-85

Water flow rate . ...Maintained at 90 percent

of flow rate specified

in high temperature cooling

test of 5.1.4.la

6.2.1.2 Heating.

Air temperature entering indoor

portion of unit 70 F [21.1°C] dry bulb

Air temperature surrounding

unit 70F[21.1°C]drybulb

Water temperature entering refrigerantto-water heat exchanger 75 F [23.9°C]

Water flow rate .. . Maintained at 110 percent

of flow rate specified

in high temperature heating

test of 5.1.4.lc

6.2.2 Voltages. Tests shall be run at the Range A

minimum utilization voltage from ARI Standard

110, Table 1, based upon the unit’s nameplate

rated voltage(s). This voltage shall be supplied at

the unit’s service connection and at rated fre

quency.

6.2.3 Procedure. The heat pump shall be operated

for one hour at the temperature conditions and

voltage specified.

6.2.4 Requirements. The heat pump shall operate

continuously without interruption for any reason

for one hour.

6.3 Voltage Tolerance Test. Ground water-source heat

pumps shall be designed and produced to pass the fol

lowing voltage tolerance test with a cooling coil air quan

thy as determined under 5.1.4.3.

6.3.1 Temperature Conditions. Temperature con

ditions shall be maintained as shown in 5.1.4. la (or in 5.1.4.lc for heating-only units).

6.3.2 Voltages.

6.3.2.1 Tests shall be run at the Range B

minimum and maximum utilization voltages

from ART Standard 110, Table 1, based upon the unit’s nameplate rated voltage(s). These vol

tages shall be supplied at the unit’s service con

nection and at rated frequency. A lower or a

higher voltage shall be used, if listed on the

nameplate.

6.3.2.2 The power supplied to the heat pump

shall be adjusted just prior to the shut down

period (See 6.3.3.2) so that the resulting voltage

at the unit’s service connection is 86 percent of

nameplate rated voltage when the compressor is

on locked rotor. For the purpose of this stan

dard, the compressor nameplate locked-rotor

amperes may be used to determine this voltage.

The proper value of no-load voltage which will

give the specified voltage at locked-rotor condi

tions should be determined prior to the test.

The locked-rotor current value of any motor

shall be measured as follows:

a. All hermetic compressor motors shall be

tested as a compressor assembly.

b. The motor winding temperature shall not

exceed 77 F [25°C] when the voltage is

applied.

c. The current reading shall be taken within

four seconds after the voltage is applied.

If the test is repeated, the motor winding

shall be allowed to cool to 77 F [25°C] or

lower before the current is reapplied.

d. The voltage at the unit service connec

tion, at the time the current reading is

taken, shall be the manufacturer’s name

plate rated voltage.

e. The locked-rotor current shall be mea

sured with an ammeter, with the rotor

actually locked.

6.3.2.3 Within one minute after the heat pump has resumed continuous operation (see 6.3.4.3),

the voltage shall be restored to the values

specified in 6.3.2.1.

6.3.3 Procedure.

6.3.3.1 The heat pump shall be operated for

one hour at the temperature conditions and vol

tage(s) specified.

6.3.3.2 All power to the heat pump shall be cut

off for a period sufficient to cause the compres

sor to stop (not to exceed five seconds) and then

restored.

6.3.4 Requirements.

6.3.4.1 During both entire tests, the heat pump

shall operate without failure of any of its parts.

6.3.4.2 The heat pump shall operate continu

ously without interruption for any reason for the

one hour period preceding the power interrup

tion.

6.3.4.3 The unit shall resume continuous oper

ation within two hours of restoration of power

and shall then operate continuously for one half

hour. Operation and resetting of safety devices

priorto establishment of continuous operation is

permitted.

6.4 Low-Temperature Operation Test (Heating).

Ground water-source heat pumps shall be designed and

produced to pass the following low-temperature opera

tion test when operating with initial air quantities as

determined in 5.1.4.3.

5
ARI STANDARD 325-85

6.4.1 Temperature Conditions.

Air temperature entering and surrounding in

door portion of unit .. 60 F [15.6°C) dry bulb

Water temperature entering refrigerantto-water heat exchanger 45 F [7.2°C]

Water flow rate Maintained at 90 percent

of flow rate specified

in low temperature heating

test of 5.1.4.ld

6.4.2 Procedure. The test shall be continuous with

the unit on the heating mode, for not less than four

hours after establishment of the specified tempera

ture conditions.

6.4.3 Requirements. During the entire test, the

heat pump shall operate without damage to the

equipment.

6.5 Insulation Efficiency Test (Cooling) (Not required

for heating-only units). Ground water-source heat

pumps shall be designed and produced to pass the fol

lowing insulation efficiency test when operating with air

quantities as determined in 5.1.4.3 with controls, fans,

dampers and grilles set to produce the maximum ten

dency to sweat, provided such settings are not contrary

to the manufacturer’s instructions to the user.

6.5.1 Temperature Conditions.

Air temperature entering and surrounding in

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

75 F [23.9°C] wet bulb

Water temperature entering refrigerantto-water heat exchanger 50 F [10°C]

Water flow rate Maintained same as in

flow rate specified in low

temperature cooling test of 5.1.4.lb

6.5.2 Procedure. After establishment of the

specified temperature conditions, the unit shall be

operated continuously for a period of four hours.

6.5.3 Requirements. During the test, no con

densed water shall drip, run or blow off from the

unit casing.

6.6 Tolerances. The conditions for the tests outlined in

6.2, 6.3, 6.4 and 6.5 are average values subject to toler

ances of ± 1.0 F [±0.56°C] for air wet bulb and dry bulb

temperatures, ±0.5 F [±0.28°C) for water temperatures

and ±1.0 percent of the reading for voltages.

Section 7. Safety Recommendations

7.1 Refrigerating System. It is strongly recommended

that the refrigerating system be designed, constructed,

and assembled so as to be in accordance with the

ANSI/ASHRAE 15-1978 Safety Code for Mechanical

Refrigeration (American Society of Heating, Refrigera

ting and Air-Conditioning Engineers, Inc.)

7.2 Product Safety. It is strongly recommended that

ground water-source heat pumps for use with duct sys

tems be designed, constructed and assembled so as to

meet the safety requirements of UL Standard for Heat

Pumps (Underwriters’ Laboratories, Inc. Standard 559,

February 1983). It is strongly recommended that freedelivery ground water-source heat pumps be designed,

constructed and assembled so as to meet the safety re

quirements of UL Standard for Air Conditioners, Room

(Underwriters’ Laboratories, Inc. Standard 484, 1982).

Section 8. Voluntary Conformance

8.1 Conformance. Conformance with this standard

shall not be claimed or implied for ground water-source

heat pumps coming within the scope of this standard

unless the heat pumps for which such claims are made

meet all the performance, safety and rating require

ments specified herein.

.

6