NATIONAL BUREAU OF STANDARDS REPORT

6129

CAPACITY TESTS OF TWO WESTINGHOUSE HEAT PUMPS

MODELS 23 RHP AND 33 RHP

by

Joseph C. Davis

Paul R. Achenbach

Report to

Myrtle Beach Air Force Base

Myrtle Beach., South Carolina

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 5901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods

for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials,

devices, and structures; advisory services to Government Agencies on scientific and technical

problems; invention and development of devices to serve special needs of the Government; and the

development of standard practices, codes, and specifications. The work includes basic and applied

research, development, engineering, instrumentation, testing,, evaluation, calibration services, and

various consultation and information services. A major portion of the Bureau’s work is performed

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inside of the back cover.

Reports and Publications

The results of the Bureau’s work take the form of either actual equipment and devices or published papers and reports. Reports are issued to the sponsoring agency of a particular project

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Information on the Bureau’s publications can be found in NBS Circular 460, Publications of

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Inquiries regarding the Bureau’s reports should be addressed to the Office of Technical Information, National Bureau of Standards, Washington 25, D. C.
NATIONAL BUREAU OF STANDARDS REPORT

NB$ PROJECT MBS REPORT

1000-30-4830 August 26 , 1958 6129

CAPACITY TESTS OF TWO WESTINGHOUSE HEAT PUMPS

MODELS 23 RHP AND 33 RHP

by

Joseph C. Davis

Paul R. Achenbach

Air Conditioning, Heating, and Refrigeration Section

Building Technology Division

to

Myrtle Beach Air Force Base

Myrtle Beach, South Carolina

IMPORTANT WOTICIE WATIQKA5. BUREAU I .Intended for use. wjt.hl Vadditional ewaiUatio

Slating 'of" this Report,

the Office of the JJIrec however, by the Gowei

to reproduce additlom

Approved for public release by the

Director of the National Institute of

Standards and Technology (NISTI

on October 9, 2015.

*y i't progress accounting documents

s Is formally published It Is subjected

luting, reproduction, or open-literature

permission It obtained In writing from

0. Ci Such permission Is not needed,

Iflcaliy prepared If that agency wishes

<NBS>

0. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
/

-
CAPACITY TESTS OF TWO WESTINGHOUSE HEAT PUMPS

MODELS 23 RHP AND 33 RHP

by

Joseph C. Davis and Paul R. Achenbach

ABSTRACT

At the request of Captain John. F. Burket, Jr., Contracting

Officer, Myrtle Beach Air Force Base, South Carolina, cooling

and heating capacity tests were made of two Westinghouse airto-air heat pumps. Models 23 RHP and 33 RHP. Before the tests

began interpretation of contract specification requirements

with regard to capacity values and conditions for testing were

agreed upon at a meeting held on April 8 , 1958, at Columbia,

South Carolina between representatives of the United States

Air Force, Westinghouse Corporation, and the National Bureau

of Standards. The tests, except for minor deviations, were

made under procedures and conditions specified by the American

Society of Refrigerating Engineers Standard No. 16-56. Results

of the tests showed compressor cooling capacities to be

21,000 and 33^900 Btu/hr and compressor heating capacities to

be 14,700 and 20,700 Btu/hr for the 23 RHP and 33 RHP models,

respectively. Thus the cooling capacity of the Model 23 RHP

was slightly less than required on type C and N houses only

and the cooling capacity of the Model 33 RHP exceeded the

requirements on all types of houses for which it was to be

used. The heating capacity of the Model 23 RHP unit ranged

from 1700 to 10,000 Btu/hr less than required and that of the

Model 33 RHP ranged from 38 OO to 6800 Btu/hr less than

required for the different house types in the project. Tests

on the supplementary resistance heaters for the 23 RHP showed

6.42 KW or 21,911 Btu/hr, and for the 33 RHP, 6.49 KW or

22,150 Btu/hr. These values are in excess of those called for

by specifications. The required resistance heating capacities

range from 8000 to 12,000 Btu/hr for the several type homes

in the Myrtle Beach project. During both specification

heating tests, modulation of the expansion valve occurred, and

in the case of the 33 RHP the modulation caused the flowmeter

to stop several times during the test run, making it impossible

to check the psychrometric measurements by the flowmeter measurement

Tests on both heat pumps were made at other "state” conditions

than those called for by the specifications, but only those

made on the 23 RHP are reported here, since those on the 33 RHP

were not part of the test request from USAF.

1 . INTRODUCTION

In accordance with a request from Captain John F. Burket, Jr.,

Contracting Officer, Myrtle Beach Air Force Base, South Carolina,

by letter dated April 9, 1958, tests were made to determine the

heating and cooling capacity of two Westinghouse heat pumps.

Models 23 RHP and 33 RHP. The interpretation of the specification

requirements with regard to capacity values and the -design conditions for testing were agreed upon at a meeting held on

April 8, 1958, at Columbia, South Carolina, between representatives of the United States Air Force, Westinghouse Corporation,

and the National Bureau of Standards. Each type house under

construction at Myrtle Beach Air Force Base had specific requirements for cooling and heating, based upon loads calculated by

the Air Force. The capacity values agreed upon and the conditions

for testing are listed below.

SPECIFICATION CAPACITY VALUES

FOR 23 RHP HEAT PUMP

Compressor Compressor

For Calculated Cooling Calculated Supplementary Heating

Housing Heat per Heat Heat Resistance per Heat

Unit Gain Pump Loss Heating Pump

(Btu/hr

)

(Btu/hr) (Btu/hr) ( Btu/hr

J

(Btu/hr)

A 19.650 19.650 24,400 8,000 16,400

B 19.650 19.650 25,400 9,000 16,400

C 22,314 22,314 30,700 6,000 24,700

M* 36.700 18.350 47,500 7,000 16,750

N* 43.250 21,625 57,200 11,000 17,600

* 2 heat pumps per house.

- 2 -

S PEC IPI CATION CAPACITY VALUES

FOR 33 RHP HEAT PUMP

Compressor Compressor

For

Housing

Unit

Calculated

Heat

Gain

Cooling

per Heat

Pump

Calculated

Heat

Loss

Supplementary

Resistance

Heating

Heating

per Heat

Pump

(Btu/hr ) (Btu/hr) (Btu/hr) (Btu/hr ) (Btu/hr)

D 26,300 26,300 30,000 5,500 24,500

F 26,300 26,300 33,700 8,000 25,700

G 29,700 29,700 37,500 11,000 26,500

H 29,700 29,700 30,000 5,500 24,500

I 29,700 29,700 33,900 8,000 25,900

J 33 ,240 33,240 39,500 12,000 27,500

K 33,240 33,240 36,000 10,000 26,000

CONDITIONS FOR TESTING 23 RHP AND 33 RHP HEAT PUMPS

Design Test Conditions Cooling Heating

Outdoor dry bulb temperature 95 °F 20° F

Outdoor wet bulb temperature 80°F (51. ^RH)

Indoor dry bulb temperature 80°F 70° F

Indoor wet bulb temperature 67 °F (50/ RH)

In the NBS test facility it would have been difficult to control humidity in the air section simulating outdoor air.

Because of this and because humidity effects on the outdoor coil

during the cooling cycle have negligible effect on capacity for

a dry coil, no effort was made to control this atmospheric condition .

It was agreed at the meeting at Columbia, South Carolina,

that all tests would be performed with the indoor blower delivering

800 CFM of conditioned air for the 23 RHP, and 1200 CFM for the

33 RHPo Static pressure at the outlet of the indoor unit was

not specified.

-3

2. DESCRIPTION OF TEST SPECIMEN

The models 23 RHP and 33 RHP heat pumps are known as ’’split

type” or "remote type” heat pumps in which one section of the

apparatus is placed outdoors and the other inside the home at a

suitable place for delivering conditioned air. The two sections

will be designated hereinafter as the outside unit and the Indoor

unit

.

During the cooling cycle, the coil of the indoor unit served

as an evaporator, absorbing heat; and during the heating cycle,

as a condenser, rejecting heat. This operational change was

accomplished by means of a change in direction of circulation of

the refrigerant through the system, using a thermostatically controlled solenoid in a four-way valve. During the tests the

solenoid was controlled by a manually operated switch to preclude

shifting from cooling to heating and vice versa. Thermostatic

expansion valves were used as the liquid refrigerant flow control

device in both the indoor and outdoor units with check valves to

bypass each when not needed. Following the new ASRE refrigerant

designations, the refrigerant in the RHP 23 was R-12 and in the

RHP 33 was R-22. A heat exchanger between the liquid line and

the suction line dcwn stream from the four-way valve served to subcool the liquid refrigerant before being pumped to the expansion

valve

.

A schematic diagram of the heat pump system and auxiliary

test instrumentation Is shown in figure 1. A list of line sizes

between the indoor and outdoor units for the two heat pumps is

shown below. Both liquid and vapor lines were about 30 ft.

23 RHP 33 RHP

1. Liquid line except for flowmeter manifold (in.) 3/8 OD 3/8 OD

2. Lines in manifold (in.

)

1/2 OD 1/2 OD

3. Vapor line (in.) 7/8 OD 7/8 OD

INDOOR UNIT

The indoor unit consisted essentially of a coil (used as

an evaporator during cooling), a blower for circulating conditioned air through the duct system of the home, a motor for

powering the blower, an expansion valve, a check valve, and two

supplementary resistance heaters. A short description of the

above components and of other smaller components is given below:

-4-

Coil, 23 RHP . Four rows of l/2-in. OD copper tubing, 14 tubes

each row, 1 1/4 in. apart - center to center. Ten aluminum

fins per in. of tube length. Dimension of coil assembly:

17 1/2 in. high, 17 1/2 in. wide, 5 1/2 in. deep.

Coil, 33 RHP . Four rows of l/2-in. OD copper tubing, 14 tubes

each row, 1 1/4 in. apart - center to center. Ten aluminum

fins per in. of tube length. Dimension of coil assembly:

17 1/2 in. high, 25 in. wide, 5 1/2 in. deep.

Blower, 23 RHP . Lau Mfg. Co., Centrifugal, 7-in. pulley, 10 in.

wide, 10 in. -diameter

.

Blower, 33 RHP . Lau Mfg., Co., Centrifugal, 7-in. pulley, 12 in.

wide, 11 -in. -diameter

.

Blower Motor (both heat pumps ) . Single-phase, type FH, continuous

operation. Westinghouse 1/3 HP, 60 cycles, 1725 RPM. Frame

56, service factor 1.35. Temperature rise 40°C. Code L.

230 volts, 2.45 amperes. Thermoguard thermal protective

device, type A. Requires oiling. Adjustable pulley, 3 1/4 in.

for 23 RHP and 3 3/4 in. for 33 RHP.

Expansion valve, 23 RHP . Non-adjustable, thermostatic type, Sporlan,

3/6-in. OD., sweat, type NSFE, charge G 2-ton F12. External

equalizer, 1/4-in. OD line, and charged thermal bulb.

Expansion valve, 33 RHP . Non-ad justable, thermostatic type,

Sporlan, 3/3 -in. OD, sweat, type NSVE, 3 1/2 G 3-ton F-22.

External equalizer, 1/4-in. OD line, and charged thermal

bulb

.

Check Valve (both heat pumps ). Kerotest, 3/8-in. OD, sweat.

Pressure activated.

Resistance Heaters . Two coil-type heaters in parallel which cut

in simultaneously when temperature in home reaches a certain

value below thermostat setting, or when the heat pump is on

a defrost cycle. On defrost the air supply to the home is

cooled for a short interval by the indoor coil. The coil

assembly includes 2 thermal safety cut-offs to prevent overheating in case of fan failure. Name plate information:

235 V, 60 cycles, 1 phase, 6.6 KW. (information given later

in this report shows that each coil dissipated about 3.2 KW

at 230 volts of test.)

-5-

Drier, RHP 23 « Sporlan Catch-all, Type 1635.

Drier, RHP 33 . Sporlan Catch-all, Type C 163-

Filter, RHP 23. One, spunglass type. Dust-stop Mfg., 20 In. high,

25 in. wide, 1 in. thick, throwaway type.

Filters, RHP 33 . Two, mounted in same plane, glasfloss type, 16

in. high, 20 in„ wide and 1 in. thick, throwaway type.

Insulation, RHP 23 ° One in. of glass fiber, completely foil

covered

Insulation, RHP 33 . One in. of glass fiber, partially foil

covered.

Description of lines inside indoor unit, both heat pumps . Liquid

line, 3/8-in. Oltj vapor line 7/8-1n. OD. Header line 7/8-

in. OD. Four distributor lines, each 3/l6-in. OD. All

lines brazed with Sil-Fos.

Housing dimensions, indoor unit, 23 RHP . Twenty-three in. high,

36 in. wide, 25 1/2 in. deep. Wall thickness 1/32 in.

Housing dimensions, indoor unit, 33 RHP . Rwenty three in. high,

3o in,, wide, 34 in, deep. Wall thickness 1/32 in.

Nameplate covering entire indoor unit, RHP 23 . F12. Type

RHP23F, Style 493D450G07., Ser. Cl 066 . Test pressure 400 lb.

Nameplate covering entire indoor unit, RHP 33 . F22. Type RHP

33F. Sytle 493U451G07, test pressure 400 lb

.

Figure 2 shows the indoor unit ready for test inside of

its enclosure.

OUTDOOR UNIT

The outdoor unit consisted essentially of a coil (used as

an evaporator during heating), a blower, a motor to drive the

blower, a hermetically-sealed motor-compressor, an expansion

valve, a check valve, a four-way valve, and a heat exchanger in

the liquid line to provide subcooling to the liquid before

being pumped to the expansion valve. These components and

others are described below.

-6 -

Coll, 23 RHP . Three rows of l/2-in„ OD copper tubing, 18 tubes

each row, 1 1/4 in. apart - center to center. Ten aluminum

fins per in. of tube length. Dimensions of coil assembly:

22 1/2 in. high, 28 in. wide, 3 3/4 in. deep 0

Coil, 33 RHP . Three rows of l/2-in. OD copper tubing, 28 tubes per

row, 1 1/4 in. apart - center to center. Ten aluminum fins

per in. of tube length. Dimension of coil assembly: 35 in.

high, 28 in. wide, 3 3/4 in. thick.

Blower 23 RHP . Preslock. Twelve in. dia., 12 in. wide. Pulley

8 in. dia.

Blower, 33 RHP . Preslock„ Fourteen-in. dia., 12 in. wide.

Pulley, S’ in. dia.

Blower Motor, 23 RHP . Westinghouse AC, single-phase, type FH, cont.

operation, 1725 rpm, 60 cycle, 230 volts., 2.45 amp., 1/3

HP. Service factor, 1.35. Thermoguard Mfg. thermal protection. Frame 56. Ser. No. MD Code L, 40°C rise, requires

oiling. Adjust, pulley 3 1/4 in. dia.

Blower Motor, 33 RHP „ Westinghouse AC, single phase, type F, cont.

operation, 1725 npm, 60 cycle, 230 volts, 3.3 amp., 1/2 HP.

Service factor 1.25. Thermoguard Mfg. Co. thermal protection. Frame O56. Ser. No. ND Code G, 40°C rise. Requires

oiling. 3 3/4 in. dia., adjust, pulley.

Motor Compre ssor, 23_RHP. Westinghouse, type CLS21, #492D962G01,

230 V, air cooled, full load amp 0 , 16. L. R. amp. 55. Ser.

No. BC2802. Pressure test, 250 lbs. Spring mounted. F-12.

Motor Compressor, 33 RHP. Westinghouse type CLS, S#492D903G01,

230 V, air cooled, full load amp., 26.1, L. R„ amp., 88.

1750 rpm. Spring mounted. F-22.

Expansion Valve, 23 RHP . Non-adjust., thermostatic, Sporlan,

3/8 -in'. OD, sweat , NSFE 2 Z, low temp. type--suction temp.

0° to -40°, F-12. External equalizer, l/4-in. OD line, and

charged thermal bulb. Line strainer before valve.

Expansion Valve, 33 RHP . Non-adjust., thermostatic, Sporlan, 3/8-

in. OD sweat, Y84NRVE 2 1/2 Z, low temp, t ype--suction temp.

0° to -40°, F-22. External equalizer, l/4-in. OD line, and

charged thermal bulb„ Line strainer before valve.

Check Valve, both heat pumps . Kerotest 3/8-in. OD, sweat,

pressure-activated.

7

-

Four-Way Valve, both heat pumps . Westinghouse . Solenoid operated

on low voltage.

Other Components . Both heat pumps have a muffler In the discharge line to minimize compressor noises in the home,

and the heat exchanger in the suction line described previously. -

Controls (a) Defrost switch for heating cycle . At low temperatures and when the outdoor atmosphere is humid, the

outdoor unit coil gradually becomes frost covered. To

defrost the coil the solenoid of the four-way valve is

actuated by a pressure sensing device and the refrigerant

flow is reversed so that the outdoor coil rejects heat

(becomes a condenser) and the frost is melted. Concurrently the outdoor fan is cut off and the supplementary

electric heaters of the indoor unit are placed into operation to warm up the conditioned air in the home which during

the brief period of defrosting is cooled by the indoor

coil

.

The device actuating the solenoid of the four-way valve is

a diaphragm which senses the difference between atmospheric

pressure and outdoor blower suction pressure. This

actuates a defrost relay. (b) The defrost limit switch

operates on a preselected high value of head pressure

after defrost, causing reactivation of the solenoid, change

in direction of the refrigerant flow and return to normal

operation. This switch ’'limits” the head pressure.

( c ) A thermally actuated device on the discharge line from

the compressor stops the compressor' when there Is low

refrigeration, mechanical failure or any situation where the

compressor temperature becomes excessive. This control is

manually reset in the outdoor unit and is manufactured by

Thermo-guard. (d) A Hi-low pressure switch opens either

when suction pressure is too low or head pressure too high

to stop operation of the compressor when there is an

obstruction in a line. Reset manually in home at thermostat* (e) Mild weather control on heating cycle . During

mild weather with satisfactory indoor temperature of about

70°F and an outdoor temperature of about 6^°

,

the outdoor

fan is turned on and off by this control to prevent overheating of the conditioned air and excessive head pressure

-8 -

Which would eventually cut off the compressor. The cycle

is actuated and the fan cut off by a head pressure above a

given threshold. During this period, while the fan is

inoperative and with the compressor still operating, both

head pressure and suction pressure decrease until a point

is reached where the fan comes back into operation and the

cycle is repeated,, (f) The electrical overload switches

on compressors and motors mentioned previously are reset

manually at the thermostat inside the home.

Insulation, both units . One in. of glass fiber top and back of

compressor compartment. Access doors both have the same

thickness of insulation. No foil.

Description of lines inside of outdoor unit, both heat pumps . Discharge line from compressor to four-way valve, 5/8 in. OD.

Suction line from compressor to four-way valve, 7/8 in. OD.

Liquid line from coil, 3/8 in. OD. Line from four-way valve

to coil, 7/8 in. OD. Vapor line inside of unit, 7/8 in. OD.

Header line, 7/8 in. OD for 23 RHP and 1 3/8 in. OD for 33

RHP„ Four distributor lines, 1/4 in. OD. All lines brazed

with Sil Fos.

Housing, outdoor unit, 23 RHP . Thirty-nine in. high, 36 in.

wide, 29 in. deep. Thickness l/l6 in.

Housing, outdoor unit, 33 RHP . Thirty-nine and one half in.

high, 36 in. wide, 29 in . deep. Wall thickness 1/16 in.

Nameplate covering entire heat pump, 23 RHP. F-12. Type RHP

23 Ho Style 493D461G01. Ser. BC 6889 . AS RE rating,

cooling 22,000. Heating 23., 100 to 15*000 Btu.

Nameplate covering entire heat pump, 33 RHP . F-22. Type 33R

Style 493R470G01, Ser. DC6296* A'S'RE rating, cooling 36,000

Btu, heating 37., 000 to 25., 000 Btu. (Representatives of the

Westinghouse Corporation informed the National Bureau of

Standards that the 25*000 Btu rating was placed on the nameplate in error. This rating representing capacity expected

from the compressor for heating at an outdoor temperature

of 20°, should have been 22,500 Btu.)

-9-

Figure 3 shows the outdoor unit with test equipment. Note

the five-in-one thermocouple system and the thermostat used for

controlling outdoor conditions during the test.

3, METHODS OP TESTING

Except for minor deviations,, the heat pump was tested

under the conditions described in ASRE Testing and Rating

Standard No. 16-56. Figure 4 shows the enclosure housing the

indoor unit and the 33-in. square test duct attached to the

outlet side of the unit- This duct housed the nozzle used for

measuring air circulation rate and the instruments for measuring

temperature and humidity of the outlet air. Because the nozzle,

mixing baffles, and screen introduced considerable resistance

in the outlet duct, an auxiliary blower powered by a one-HP

motor was provided at the downstream end of the 33-in. duct.

Adjustment of external static resistance when such adjustment

was necessary was made by a wooden slide-type damper at the

outlet of the auxiliary blower. The auxiliary blower, return

air heaters, and humidifier are shown in figure 5-

ASRE Standard 16-56 requires that two independent measuring

methods be used during the test, each as a check on the other.

One method, known as the psychrometric method, involved measuring

the mass-flow of air through the indoor unit and the change in

enthalpy of the air across the unit. The other method involved

determination of the flow of refrigerant through the indoor coil

and the change in enthalpy of the refrigerant across the indoor

coil. A correction to the total enthalpy change of the refrigerant is necessary, either by adding or subtracting the heat

equivalent of the electrical energy supplied to the indoor

blower motor depending on whether the heating or cooling cycle

is in use before comparing it with the result of the psychrometric method. Values obtained by the two methods should not

differ by more than six percent.

Mass flow of air in the psychrometric method was obtained

by measuring humidity and temperature conditions of the air

entering the long-radius nozzle and the static pressure drop

across the nozzle. Enthalpy change of the air was determined by

measuring temperature, humidity, and barometric pressure of the

air entering the indoor unit, and in the duct immediately after

it left the unit.

- 10-

For both heat pumps the volume air flow rate was set by

adjusting the blower pulley before the test with the compressor

inoperative and with the indoor blower forcing dry air over the

indoor coil. Thereafter the damper at the outlet to the auxiliary

blower remained unchanged

„

Flow of refrigerant was measured by means of a flowmeter

in the liquid line of the system--a Potter Electronic type with

an impeller which generated an electrical pulse on each revolution. A Potter counter coupled to the flowmeter served to translate the pulses into gal-unit time. By knowing temperature of

the liquid in the line, the flow was eohverted to mass flow.

Enthalpy change was determined by temperature and pressure

measurements at the inlet and outlet of the indoor coil. For

accurate measurement of capacity by the refrigerant flow method

it was imperative that there be no gas bubbles in the liquid

refrigerant as it passed through the meter, and that the liquid

refrigerant all be evaporated in the coil.

It was possible to maintain "state” conditions for both

cooling and heating with the use of a test structure having two

controlled temperatures.

During both tests, power consumed by the indoor blower,

outdoor fan, and compressor was read from separate watthour

meters. Simultaneous readings were made of currents and voltages.

The various meters, together with the other instruments for

measuring temperature and humidity, are shown in figure 6.

In each heat pump test, the following "state" conditions

for the indoor and outdoor air were maintained during the cooling

cycle in accordance with contract specifications:

95 °F DB outdoors

80°F DB inside

67°B WB inside (50 percent relative humidity)

For the heating test, the following "state" conditions for

the indoor and outdoor air were maintained in accordance with

the contract specifications:

20°F DB outdoors

70°F DB indoors

- 11 -

The same refrigerant charge was used for the cooling test

as for the heating test. For the 23 RHP the Westinghouse representative and the NBS project leader agreed to set this charge

for optimum capacity on the cooling cycle. This charge

remained constant during a number of subsequent cooling and

heating tests at "state” conditions other than those specified

inthe contract specifications and was still the same for the

test at 20° outdoors and 70° indoors. When this cold temperature was reached, however, bubbles appeared in the sight glass

of the liquid line indicating a shortage of refrigerant.

Although the test was completed, the Westinghouse representative

thereupon requested the addition of another pound of refrigerant

and both the specification heating and cooling tests were

repeated. The additional tests at other "state” points were not

repeated but the significance of the shortage of one pound of

refrigerant on the values obtained will be discussed in paragraphs following.

In light of this experience the representative and the NBS

project leader agreed to set up the charge for the 33 RHP on

the heating cycle at 20°F, with the charge remaining constant

through the cooling test.

Surveillance of charge was always made with the heat pump

on cooling and with the outdoor temperature at 95 °F, the indoor

temperature at 80°F, and the indoor relative humidity at 50 percent. Checks were made for pressures, refrigerant vapor and

liquid temperatures, superheating, subcooling, flowmeter count,

and change in air temperature across the indoor coil. During

both heating tests after the correct charge was made, the outdoor temperature was raised to 95°F as soon as possible and

these check points determined.

The tests on the RHP 23 with a refrigerant shortage of

one lb were made at the six "state" conditions for cooling and

three "state" conditions for heating shown below.

Cooling Heating

Outdoor Temp Indoor Temp Indoor RH Outdoor Temp Indoor Temp

105 °F 80 °F 50 % 50 °F 70 °F

95 80 50 35 70

85 80 50 20 70

75 80 50

95 75 50

85 75 50

- 12 -

The tests at other than specification design conditions were

made in conformance with a request from the USAF for information

in addition to that required by specification.

Due to a shortage of time and the need for curtailing

expense,, only the two specification tests were performed on the

RHP 33 under the USAF test request. Other tests at the ’'state”

points indicated below were performed at the expense

of NBS when it was not too time consuming and too expensive

to perform them. These "state" points are indicated below.

Outdoor Temp.

Cooling

Indoor Temp. Indoor RH

Heating

Outdoor Temp. Indoor Temp.

105 °F 80 °F 50 % 50 °F 70 °F

85 80 50 35 70

The results of the observations at these points are not

reported, but are available for use by USAF, and the Westinghouse Corporation with the permission of USAF.

Before each test run, a minimum of one hour steady-state

conditions was held before the data were considered valid.

During most test runs, readings were taken every ten minutes

for at least one hour. In each case, except the cases noted

below, the hour representing the steadiest conditions was used

for evaluating performance. In the specification cooling test

for the 33 RHP, the best two hours were used. In the specification heating test for the 23 RHP, due to cycling of the

expansion valve, readings were taken every five minutes, and

data covering a period of 55 minutes were used. In the specification heating test for the 33 RHP, readings were taken every

ten minutes and data covering a two-hour period were used.

-13-

4. TEST RESULTS

A. 23 RHP, Cooling Test

ASRE Standard 16-56 requires that values obtained by the

psychrometric and flowmeter methods be averaged to obtain the

rated capacity of the heat pump. The results obtained by the

two measuring methods during the cooling test, and the total

rated cooling capacity of the model 23 RHP are shown below.

This capacity, it will be noted, includes a correction for

deviation of barometric pressure from standard barometric

pressure. This is in accordance with ASRE 16-56, which allows

an increase of 0.8 percent of capacity for each inch of barometer

reading below 29.92 in. of Hg during the cooling test.

Summary of Cooling Capacity Values (Btu/hr)

Test Rounded

Value Value

By psychrometric method 21,060

By flowmeter method 20,800

Average 20,930

Allowance for deviation of barometric

pressure from normal 50

Total 20,980 21,000

Following is a summary of the averages of the more significant data during the cooling test.

Psychrometric Method

Temperatures (°P)

At inlet to enclosure around indoor unit

At outlet of indoor unit in duct

Temperature difference across indoor

coil

At inlet to outdoor unit

80.0

61.7

18.3

95.0

-l4-

Relative humidities ($)

At inlet to enclosure around indoor unit

At outlet of indoor unit in duct

Static pressure across nozzle (in. of H2O)

Volume air flow at nozzle (cfm)

Mass air flow at nozzle (lb dry air/hr)

Barometric pressure (in. of Hg)

Diameter of nozzle (in.)

Nozzle coefficient

Static pressure at indoor blower outlet

( In> ofk -ft 2

0)

Flowmeter Method

Temperatures ( °F)

In vapor line leaving coil of indoor unit

In liquid line entering coil of indoor unit

Superheat at indoor coil outlet

Subcooling at indoor coil inlet

In discharge line of compressor

In suction line of compressor

Pressures (psig)

Compressor discharge

In liquid line entering coil of indoor unit

In vapor line leaving coil of indoor unit

In suction line of compressor

Difference in pressure across flowmeter was

negligible.

Potter meter count for 10 minutes

* Refrigerant flow, gal/min = Count for one

50.0

82.3

• 555

788

3581

20.57

7.009

.987

.023

53.7

102.7

10.0

15.2

209.2

83.8

I63o0

155.0

40.5

39.2

220.7*

minute x 100

3365.5

-15-

Motor power consumption (Watts)

Indoor blower 264

Outdoor blower 346

Compressor 2481

Total 3091

Coefficient of performance 1.99

Motor voltages (Volts)

Indoor blower 230.6

Outdoor blower 230.6

Compressor 230.6

Motor currents (Amperes)

Indoor blower 2.34

Outdoor blower 2.32

Compressor 12.35

B. 23 RHP, Volume Air Flow

When the volume air flow from the blower of the indoor unit

was set by pulley adjustment before the cooling test without the

compressor running and at an indoor temperature of about 75 °F;

the following results were obtained.

Volume air flow at nozzle (cfm) 806

Static pressure at indoor blower outlet

(In. of H20) 0.08

No subsequent pulley adjustment or damper adjustment affecting

static pressure was made during the cooling and heating tests on

the 23 RHP.

- 16 -

C. 23 RHP, Heating Test

The heating test performed in accordance with the procedures described in ASHE Standard 16-56, except for minor

deviations, gave the following results. The ASRE standard

allows an increase of 2.0 percent of capacity for each inch of

deviation below standard barometric pressure for the heating

condition.

Summary of Heating Capacity Values (Btu/hr)

Test Rounded

Value Value

By psychrometric method 14,580

By flowmeter method 14,590

Average 14,585

Correction for deviation of barometric pressure

during test from standard barometric

pressure 80

14,665 14,700

Following is a summary of the averages of the more significant data observed during the heating test.

Psychrometric Method

Temperatures ( °F)

At inlet to enclosure around indoor unit 69.8 DB

At outlet of indoor unit in duct 87 . 1 DB

Temperature difference across indoor coil 17 .

3

At inlet to outdoor coil 20.5 DB

Relative humidity of Indoor air in duct ($) 12.3

Static pressure across nozzle (in. of HgO) O .56

-17

Volume air flow at nozzle (cfm) 807

Mass air flow at nozzle (lb dry air/hr) 3496.3

Barometric pressure (in. of Hg) 29.65

Diameter of nozzle (in.) 7.009

Nozzle coefficient . 987

Static pressure at indoor blower outlet .080

(In. of H

20)

Flowmeter Method

Temperatures ( °F)

In vapor line entering coil of indoor unit 154.0

In liquid line leaving coil of indoor unit 89.5

Superheating at vapor line entering coil of

indoor unit 56.9

Subcooling at liquid line leaving coil of

indoor unit 7.0

Pressures (psig)

Compressor discharge 115

In vapor line entering coil of indoor unit 114

In liquid line leaving coil of indoor unit 114

In liquid line leaving flowmeter 108

Pressure difference across flowmeter 6.0

(Suction pressure not observed.)

Potter meter count for 10 minutes 561*

* Refrigerant flow, gal/min = Count for 1 minute x 100

18133.8

- 18 -

Motor power consumption (Wattsi)

Indoor blower

Outdoor blower

Compressor

255

426

1728

Total 2409

Coefficient of performance 1.79

Motor voltages (Volts)

Indoor blower

Outdoor blower

Compressor

229.1

229.8

229.8

Motor currents (Amperes

)

Indoor blower

Outdoor blower

Compressor

2.31

2 06 O

8.55

Power dissipated by supplementary resistance

heaters (KW) a. 3

b. 3

D. 23 RHP, Other Tests

As discussed previously, when the heating test at the 20°

outdoor temperature was completed, another pound of refrigerant

was added to the system and another heating test-run made at

the same outdoor temperature. It was found that capacity

increased by 700 Btu/hr with the extra lb, and the second run

was used as the specification test. With the same refrigerant

charge, another cooling test was performed and here again an

increase of 700 Btu/hr occurred. This cooling test also served

as the specification test. The results for both heating and

cooling reported above on thp 23 RHP heat pump were those

observed after adding the pound of refrigerant.

Before the two final specification tests were performed,

the total of six cooling tests and three heating tests were performed with the original low charge. Two of these, one for

cooling and one for heating, were at design conditions.

-19-

The results of these tests with low refrigerant are shown

graphically in figure 7 for the six cooling tests* and in

figure 8 for the three heating tests.

E. 33 RHP* Cooling Test

The cooling test for the 33 RHP gave the following results.

Summary of Cooling Capacity Values (Btu/hr)

Test Rounded

Value Value

By psychrometric method 34,960

By flowmeter method 32*610

Average 33,785

Correction for deviation of barometric pressure from standard

barometric pressure 70

33,855 33,900

Following is a summary of the more significant data

observed during the cooling test.

Psychrometric Method

Temperatures ( °F)

At inlet to enclosure around indoor unit 79.8 DB

At outlet of indoor unit in duct 59.8 DB

Temperature difference across indoor coil 20.0 DB

At inlet to outdoor unit 94.8 DB

Relative Humidities {%)

At inlet to enclosure around indoor unit 49.-4

At outlet of indoor unit in duct 84.5

- 20-

Static pressure across nozzle (in. of H2 0)

Volume air flow at nozzle (cfm)

Mass air flow at nozzle (lb of dry air/hr)

Barometric pressure (in. of Hg)

Diameter of nozzle (in.)

Nozzle coefficient

Static pressure In Indoor blower outlet

('In. of H^O)

Flowmeter Method

Temperatures ( °F)

In vapor line leaving coll of indoor unit

In liquid line entering coil of indoor unit

Superheating in vapor line leaving coil of

indoor unit

Subcooling in liquid line entering coil of

Indoor unit

In compressor discharge line

In suction line of compressor

Pressures (psig)

Compressor discharge

In liquid line before flowmeter

In liquid line entering coil of indoor unit

Pressure difference across flowmeter

In vapor line leaving coil of Indoor unit

Potter meter count for ten minutes

Motor power consumption (Watts)

Indoor blower

Outdoor blower

Compressor

Total

* Refrigerant flow, gal/min = Count for one minute

3365.5

1.24

1179

5325

29.65

7.009

.99

- 0.01

54.3

103.8

11.4

11.8

245.5

85.3

267

251

249

2

73.9

297.8*

358

564

4206

5128

100

- 21 -

Coefficlent of performance

Motor voltages (Volts)

1.94

Indoor blower

Outdoor blower

Compressor

230.1

230.0

230.0

Motor current (Amperes)

Indoor blower

Outdoor blower

Compressor

2.58

3.51

20.21

F. 33 RHP, Volume Air Flow

When the volume air flow from the blower of the Indoor unit

was set by pulley adjustment before the heating test with the

compressor running and at an indoor temperature of about 75 °F,

the following results were obtained. (The heating test was performed before the cooling test on the 33 RHP.

)

Volume air flow at nozzle (cfm) 1206

Static pressure at indoor blower outlet

(In. of H

2 0) 0.07

No subsequent pulley adjustment or damper adjustment affecting

static pressure was made during the cooling and heating tests on

the 33 RHP.

G. 33 RHP, Heating Test

The heating test for the 33 RHP gave the following results.

Summary of Heating Capacity Values (Btu/hr)

Test Rounded

Value Value

By psychrometric method 20,610

Correction for deviation of barometric

pressure from standard barometric

pressure

.

110

20,720 20,700

- 22 -

Because modulation of the expansion valve caused the flowmeter to stop intermittently, it was impossible to make a

capacity calculation based upon refrigerant flow.

Following is a summary of the more significant data observed

during the heating test.

Psychrometric Method

Temperatures ( °F)

At inlet to enclosure around indoor unit 69*7 DB

At outlet of indoor unit in duct 85.8 DB

Temperature difference across indoor coil 16. 1 DB

At inlet to outdoor unit 19*9 DB

Relative humidity of indoor air in duct {%) 10.2

Static pressure across nozzle (in. of H2O) 1.28

Volume air flow at nozzle (cfm) 1220

Mass air flow at nozzle (Lb of dry air/hr) 5303*5

Barometric pressure (in. of Hg) 29.56

Diameter of nozzle (in.) 7.009

Nozzle coefficient . 99

Static pressure at indoor blower inlet (in. of H2 O) 0.070

Other temperatures ( °F

)

In vapor line entering coil of indoor unit 199.0

In liquid line leaving coil of indoor unit 85.4

Superheat in vapor line entering coil of indoor

unit 107.4

Subcooling in liquid line leaving coil of

indoor unit 6.6

In compressor discharge line 234.1

In compressor suction line 49.1
:
-23-

Pressures (psig)

In compressor discharge line 179

In vapor line entering coil of indoor unit 177

In liquid line leaving coil of indoor unit 177

In liquid line beyond flowmeter 172

Difference in pressure across flowmeter 5

In suction line of compressor 30

Motor power consumption ( Wat t s

)

Indoor blower 331

Outdoor blower 678

Compressor 2608

Total 3617

Coefficient of performance 1 . 68

Motor voltages (Volts)

Indoor blower 230.1

Outdoor blower 230.2

Compressor 230.3

Motor current (Amperes)

Indoor blower 2* 45

Outdoor blower 3.99

Compressor 12.84

Power dissipated by supplementary resistance

7Teaters (tcW)' a. 3.25

b. 3.24

H. Comparison of 23 RHP operation at 230 volts and 220 volts

Following a test run on the 23 RHP for cooling,, the voltage

on all three motors of the system was reduced to 220 volts.

This voltage was maintained for 40 minutes. During this 40-

minute period, little change In the important temperature,

pressure, and refrigerant flow values was noted, indicating

that capacity on the heat pump should be about the same at

-24-

220 volts as at 230 volts. An Increase In compressor current

drain was noted, but the change in power was not significant.

A comparison of data with the system operating at 230 volts

and operating at 220 volts is shown below. Each set of data

represents 40 minutes. Readings were taken every ten minutes.

Outside temperature was 95°.» inside temperature 80° and inside

relative humidity 50 percent. One pound of refrigerant had been

added before this test.

Temperatures ( °F)

230 volts 220 volts

At inlet to enclosure around

indoor unit

At outlet of indoor unit in duct

Temperature difference across

indoor coil

In vapor line leaving coil of

indoor unit

In liquid line entering coil

of indoor unit

Potter meter count for 10 minutes

Pressures (psig)

In vapor line leaving coil of indoor

unit

In liquid line entering coil of

indoor unit

In suction line of compressor

Power consumption (Watts

)

Indoor blower 40 min.

Outdoor blower 40 min.

Compressor 40 min.

80.1

62.2

80.2

62.2

17 °9 18.0

54.6 54.6

101.9 101.9

222.*5 221.-5

4o„ 6 40.6

154.2

38.1

153.0

38.1

174

229

1714

167

223

1706

Total 2117 2096

-25-

Motor voltages (Volts) 230 volts 220 volts

Indoor blower

Outdoor blower

Compressor

229-6

230.0

229.6

219.0

219.-4

219.2

Motor current (Amperes)

Indoor blower

Outdoor blower

Compressor

2.37

2.33

12.46

2.23

2.30

12.87

Static pressure across nozzle .055 .055

5. DISCUSSION OP TEST RESULTS

Starting with the pulley adjustment on the indoor blower

motor, without the compressor running, it was found during the

cooling tests that the static pressure at the blower outlet

became very low in one case and slightly negative in another.

This phenomenon was the result of a change of air density and

an interaction of the characteristics of the indoor unit blower

and auxiliary blower. At the conclusion of the cooling test

RHP 33* it was demonstrated that the pulley of the indoor

blower could be further adjusted to deliver the required amount

of air against an external static pressure of 0.10 of H2O or

greater, such as might occur in a duct system of a house.

This operation also required adjustment of the slide damper

on the auxiliary blower. There was no significant rise in

blower motor current.

To determine the amount of oil traveling through the lines

with the refrigerant and the effect of this oil on the flowmeter registration, the refrigerant was sampled after the tests

on both heat pumps. The refrigerant, taken from the line

while the heat pump was operating, was discharged into special

flasks pre-cooled by dry ice, and then allowed to evaporate

slowly as the ice melted, leaving a residue of oil. or the

23 RHP the percentage of oil to refrigerant was 0.50 by volume,

whereas for the 33 RHP the percentage was 2.0 by volume.

-26-

Throughout the cooling test on the 33 RHP, a pressure difference of 16 psi existed between the compressor discharge and

the liquid line entering the coil of the indoor unit as

measured by calibrated pressure gages. This difference was

estimated to be six psi greater than would normally be caused

by the four-way valve, the outdoor distributors, coil, check

valve, etc. Of this, about two lb was brought about by the

pressure drop across the flowmeter-manifold system. It was

estimated that the excessive pressure drop of six lbs, whatever

its cause, could cause a loss in capacity of not greater than

300 Btu/hr, and was consequently not considered serious enough

by the Westinghouse representative to cause alterations and a

retest. Throughout the same tests the needle of the gage

measuring the pressure of the liquid going to the coil of the

indoor unit, jumped to a high reading and returned instantly

to the normal reading. This occurrence was repeated at undetermined intervals of two to ten minutes. The phenomenon was not

occasioned by the gage.

Through the heating tests on the 33 RHP, the expansion

valve fluctuated between two extremes of position with a corresponding fluctuation in vapor temperature at the coil outlet

and temperature of the conditioned air from the Indoor unit.

The refrigerant flow varied to such an extent that the flowmeter

stopped a number of times during the run. Some cycling was

expected by the Westinghouse Company at an outdoor temperature

of 20°, and was considered a design problem that needed further

attention. The representative was somewhat surprised however,

when he learned that the cycling occurred to a smaller degree

at 35°R and 50°P. The stoppage of the flowmeter during the

20° test run obviated the possibility of a flowmeter calculation,

and only a psychrometric value is reported. The flowmeter

capacity value Sr the test at 50° outdoors, was about six percent lower than the psychrometric value.

After both heating tests, an analysis of the effect of the

expansion valve cycling on the distribution of temperature

values was made. For example, it was possible for a wave function

during a period to be heavily weighted in favor of high temperature values, and a simple averaging of temperatures could not be

used. In the analysis of the 33 RHP readings were made of the

temperature of the vapor at the Inlet to the indoor coil every

three seconds for 180 seconds, and four complete almost sinusoidal

cycles were obtained, indicating that there was an even distribution and the simple averaging process could be used. The same

result was obtained for the 23 RHP.
*

‘

U .

'
-27-

Immediately preceding the taking of data on the 20° test

run, the outdoor unit was defrosted. Halfway through the run,

the unit frosted slightly, although the average suction pressure during the test period showed little decrease as evidence

of capacity loss. The run was continued, however, rather than

defrosting and losing conditions. The 23 RHP did not frost

during the test.

All pressure readings where the line to the gage held

liquid, were corrected for altitude difference between the gage

and the point in the system where the pressure indication was

desired.
.

,• .
INDOOR

UNIT

OUTDOOR

UNIT

FIGURE

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U. s. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of the National Bureau of Standards at its headquarters in Washington,

D. C., and its major laboratories in Boulder, Colo., is suggested in the following listing of the

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