AlllOS 10ED77

NBSIR 80-2002

Method of Testing, Rating and

Estimating the Heating Seasonal

Performance of Heat Pumps

Walter H. Parken, George E. Kelly, and

David A. Didion

Building Thermal and Service Systems Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, D.C. 20234

April 1980

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

! 80-2002

1 1980

lUnONAlf or 0TAin>AftD8

htBSABt

NOV 2 4 1980

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NBSIR 80-2002

METHOD OF TESTING, RATING AND

ESTIMATING THE HEATING SEASONAL " ^ PERFORMANCE OF HEAT PUMPS / ^

Walter H. Parken, George E. Kelly, and

David A. Didion

Building Thermal and Service Systems Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

U.S. Department of Commerce

Washington, D.C. 20234

April 1980

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity. Technology, and Innovation

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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ABSTEIACT

Test and rating procedures are presented for electrically-driven residential

air-to-air heat pumps operating in the heating mode. The procedures are designed to include the effects of part-load (cyclic) operation, variations

in outdoor temperature, and frost formation on the heating performance.

Using the test procedure results, a calculation procedure is presented for

estimating the heating seasonal performance (HSPF) and cost of operation

of residential heat pump units.

Key Words: Central air conditioners; central heating equipment; heat pumps;

heating seasonal performance; residential heating; seasonal performance; test method.

iii
TABLE OF CONTENTS

Page

LIST OF TABLES AND FIGURES vi

NOMENCLATURE vii

1. SCOPE AND PURPOSE 1

1.1 DEVELOPMENT OF TEST PROCEDURES 1

2. RECOMMENDED TESTING AND RATING REQUIREMENTS 3

2.1 INTRODUCTION 3

2.2 REQUIREMENTS FOR HEAT PUMPS WITH SINGLE-SPEED CONtPRESSORS

,

TWO- SPEED COMPRESSOR, TWO COMPRESSORS AND COMPRESSORS

INCORPORATING CYLINDER UNLOADING 4

2.2.1 General Test Condition Requirements for all Tests .. 6

2.2.2 High Temperature Test Conditions at 47°F (8.3°C) or 62°F (16.7°C) 6

2.2.3 Cyclic Performance Test Conditions 7 2.2.4 Frost Accumulation Test Conditions 7 2.2.5 Low Temperature Test Conditions 7

3. HEAT PUMP HEATING PERFORMANCE TEST PROCEDURES 8

3.1 INTRODUCTION 8

3.2 STEADY-STATE HIGH TEMPERATURE TEST PROCEDURE AT OUTDOOR

TEMPERATURES OF 47°F (8.3°C) OR 62°F (16.7°C) 9 3.2.1 Available Test Methods 9 3.2.2 Air Flow Rate, Instrumentation and Data

to be Recorded 10

3.2.3 Test Preparation and Performance 11

3.2.4 Test Tolerances 12

3.2.5 Data Analysis and Results 12

3.3 CYCLIC PERFORMANCE TEST PROCEDURE 13

3.3.1 Available Test Methods 13

3.3.2 Air Flow Rate, Instrumentation and Data

to be Recorded 13

3.3.3 Test Preparation and Performance 13

3.3.4 Test Tolerances 14

3.3.5 Data Analysis and Results 14

3.4 FROST ACCUMULATION TEST PROCEDURE 16

3.4.1 Available Test Methods 16

3.4.2 Air Flow Rate, Instrumentation and Data to

be Recorded 16

3.4.3 Test Preparation and Performance 17

3.4.4 Test Tolerances 17

3.4.5 Data Analysis and Results 18

3.5 LOW TEMPERATURE TEST PROCEDURE 19

iv
TABLE OF CONTENTS (cont.)

Page

3.5.1 Available Test Methods 19

3.5.2 Instrumentation and Data to be Recorded 19

3.5.3 Test Preparation and Performance 19

3.5.4 Test Tolerances 20

3.5.5 Data Analysis and Results 20

4. CALCULATION OF THE HEATING SEASONAL PERFORMANCE FACTOR (HSPF)

AND SEASONAL COST OF OPERATION 20

4.1 INTRODUCTION 20

4.2 CALCULATING THE HSPF AND SEASONAL OPERATING COST FOR

HEAT PUMPS WITH SINGLE-SPEED COMPRESSORS 21

4.3 CALCULATING THE HSPF AND SEASONAL OPERATING COST FOR

HEAT PUMPS WITH TWO-SPEED COMPRESSOR OR TWO COMPRESSORS,

OR COMPRESSORS INCORPORATING CYLINDER UNLOADING 25

APPENDIX A: SAMPLE CALCULATIONS FOR A SINGLE-SPEED COMPRESSOR

HEAT PUMP 39

APPENDIX B: SAMPLE CALCULATIONS FOR A TWO- SPEED COMPRESSOR

HEAT PUMP 46

V
LIST OF TABLES AND FIGURES

Page

Table 1 SUMMARY OF TEST REQUIREMENTS 31

Table 2 STEADY-STATE HIGH TEMPERATURE AND LOW TEMPERATURE TEST

TOLERANCES 32

Table 3 TEST TOLERANCES FOR THE ON-PERIOD PORTION OF CYCLIC

PERFORMANCE TESTS 33

Table 4 TEST TOLERANCES FOR FROST ACCUMULATION TESTS 34

Table 5 MAJOR CLIMATIC REGIONS IN THE CONTINENTAL U.S.A 35

Table 6 STANDARDIZED DESIGN HEATING REQUIREMENTS (kBtu/h) 36

Table 7 EXAMPLE OF INFORMATION WHICH WOULD ASSIST A CONSUMER

IN PURCHASING A HEATING APPLIANCE 37

Figure 1 HEATING LOAD HOURS (HLH) FOR THE UNITED STATES 38

Table Al SAMPLE DATA REQUIRED TO CALCULATE THE HSPF FOR A

SINGLE-SPEED HEAT PUMP 4 3

Table A2 SAMPLE WORKSHEET USED TO EVALUATE THE HSPF AND THE

SEASONAL COST OF OPERATION FOR A SINGLE-SPEED

COMPRESSOR HEAT PUMP 44

Table A3 HSPF VALUES FOR THE EXAMPLE SINGLE-SPEED COMPRESSOR

HEAT PUMP 45

Table B1 SAMPLE DATA REQUIRED TO EVALUATE THE HSPF FOR A

TWO-SPEED COMPRESSOR HEAT PUMP 53

Table B2 EXA>-IPLE WORKSHEET FOR EVALUATING THE HSPF AND SEASONAL

COST OF OPERATION FOR A TWO-SPEED HEAT PUMP 54

Figure B1 SAMPLE BUILDING LOAD AND TWO-SPEED HEAT PUMP

PERFORMANCE CURVES 55

Vi
NOMENCLATURE

BL(Tj) building heating load at an outdoor temperature Tj, (kBtu/h)

C factor equal to 0.77 used to improve agreement between

calculated and measured building loads.

degradation factor used to characterize the degradation in

cyclic performance; defined by equation 3.3.

COP coefficient of performance, defined as the net heating done

over a specified period of time divided by the total electrical

energy input over the same time interval.

^pa specific heat of air-water mixture per pound of dry air,

(Btu/lb ®F).

DHR design heating requirement, defined by equations (4.2), (4.3)

and Table 6, (kBtu/h).

t(Tj) total electrical power input to a heat pump at an outdoor

temperature T^, (kW).

eNtj) total electrical power input to a heat pump at low speed

(single-compressor operation or one cylinder loaded) k=l

,

or at high speed (two-compressor operation or all cylinders loaded) k=2, at a representative outdoor temperature

Tj, (kW).

total electrical power input to a heat pump operating in a steady-state mode at an outdoor temperature, T^, (kW).

^DEF total electrical energy usage of a heat pump divided by the

defrost test time. The defrost test time starts at a defrost

termination and ends at the next defrost termination, (kW).

^CYC total electrical energy usage of a heat pump used in one complete on-off cycle during a cyclic test including any

adjustments for fan energy usage, (kWh).

E(Tj)

N

the ratio of the total electrical energy usage of a heat pump

in temperature bin j to the total number of temperature bin

hours in the heating season, (kW).

HLF heating load factor; defined as the ratio of the cyclic heating

done over a complete cyclic test period consisting of an "off"

and an "on" period to the steady-state heating that would have

been done over the same period of time. See equation 3.4 for

basic definition.

HLH heating load hours, presented in Table 5 and Figure 1 and

equation 4.1, (h).

vil
asPF heating seasonal performance factor for heat pumps evaluated by

equations (4.4) or (4.13).

j outdoor dry bulb temperature bin number, (e.g.: 1, 2, 3,... n.

)

N total number of hours in the heating season, N = n ., (h).

j

j

"j

N

t* Vi fractional number of hours in the j temperature bin.

total number of hours in the j temperature bin, (h).

PLF,

PLF(X)

part load factor, defined as the ratio of the cyclic COP to the

steady-state COP. See equation 4.9 for basic definition.

Q(Tj)

qNtj)

heating capacity at an outdoor temperature Tj, (kBtu/h).

heating capacity at either low speed (or single compressor

operation or all cylinders loaded) k=l, or high speed (two com- pressor operation or all cylinders loaded) k=2, (kBtu/h).

steady-state heating capacity at an outdoor temperature X.,

(kBtu/h)

%EF the ratio of the net heating done during frosting to the total

defrost cycle time starting at defrost termination and ending at

the next defrost termination, (kBtu/h).

^DEF the net heating done over a complete defrost cycle; defined by

equation 3.5, (kBtu).

^CYC the net cyclic heating during a cyclic test, including any

adjustment for fan energy, (kBtu).

RH(Tj)

N

the ratio of supplementary resistance heat required at an outdoor temperature T- to the total number of hours in the

heating season, (kW).

representative outdoor dry-bulb temperature for temperature

bin j, (°F). See Table 5.

^OD 97 1/2%-outdoor design temperature for a particular geographical

region, (°F).

”^OFF outdoor temperature at which the heat pump compressor is

automatically turned off, (°F).

”^ON

outdoor temperature at which the heat pump compressor is

automatically turned on after having been off, (°F).

viii
Tal(') dry-bulb temperature of the air entering the indoor portion of

a heat pump, (“F).

Ta2<>^) dry-bulb temperature of the air leaving the indoor portion of

a heat pump, (°F).

t time, (h).

^ON

1 Vn

duration of time the eompressor is on in one on-off eyele, (h).

speeifie volume of air-water vapor mixture, at the dry-bulb

temperature, humidity ratio, and pressure measured at the

nozzle, (ft^/lb).

indoor air flow rate at the dry-bulb temperature, humidity ratio

and pressure existing at the nozzle during the test, (CFM).

Wn humidity ratio, (lb. of moisture/lb. of dry air)

X, X(Tj), load factor at an outdoor dry bulb temperature, T.. See equation

4.8 for basic definition.

r defined by equations 3.2 and 3.6, (®F-hr).

fi (T.),

6"(T^)

heat pump low temperature compressor cut-off factor. See equations

4.7, 4.19, 4.33, respectively.

Z

j indicates summation over all applicable temperature bins.

eye

SUPERSCRIPTS AND SUBSCRIPTS

cyclic

DEF frost-defrost

j temperature bin number, see Table 5.

k mode of operation for two-speed compressor, two compressor heat

pumps, or cylinder unloading heat pumps. Low speed or single

compressor operation or one cyclinder loaded is designated as k=l while high speed or dual compressor operation or all cylinders loaded is designated as k=2

ss steady-state.

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1. SCOPE AND PURPOSE

The recommended test and rating procedures are Intended to be applied to

electrically driven single phase air-to-air heat pumps, which have cooling

capacities (at test A-type conditions (NBSIR 77-1271)) of 65,000 Btu/h

(19.045 kW) or less. For electrically driven heat pumps which supply a heating only function, the procedures apply for those units having capacities of 70,000 Btu/h (20.510 kW) or less (at the 47“F (8.3°C) High Temperature Test conditions (see section 2.2.2)). They do not apply to water

source heat pumps or hybrid systems which supplement the heat pump output

by burning fossil fuel. For two speed compressor units, units with two

compressors, or units incorporating compressor cylinder unloading, the

cooling and heating capacities referred to above are the capacities

obtained with the heat pump operating on the high compressor speed or with

both compressors in operation, or with all cylinders in operation.

The purpose of the recommended test and rating requirements are generally,

to provide performance information from which a heat pump unit may be properly sized to a heating load, to provide information from which a consumer

may estimate his or her heating costs and to provide information from which

seasonal energy efficiency and operating cost comparisons can be made

between heat pump models and between different types of heating systems.

1.1 DEVELOPMENT OF TEST PROCEDURES

The test procedures presented herein have been developed within the framework that the tests should not be unduly burdensome for the manufacturer

to perform and should yield accurate and repeatable results. The results are to be applied to a heating seasonal performance calculation and to

provide sizing information for residential heating loads. The test procedures should result in a fair and accurate comparison between units having

different design features. The recommended test procedures have been

adapted from the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standard 37-69 entitled "Methods of Testing for

Rating Unitary Air Conditioning and Heat Pump Equipment" and from a NBS

report entitled "Method of Testing, Rating and Estimating the Seasonal

Performance of Central Air Conditioners and Heat Pumps Operating in the

Cooling Mode", NBSIR 77-1271. This latter report formed the basis for the

test procedure for residential central air conditioning equipment published

in the Federal Register Vol. 42, No. 227, November 25, 1977.

A steady-state test at 47®F (8.3“C) is required and is the same as the ARI

(Air Conditioning and Refrigeration Institute) Standard 240-76 high temperature test. In addition, in order to account for the performance degradation due to the unit cycling on and off, a cycling test is also specified

at the same ambient condition. The percent on-time for the test was chosen

to be 20% which resulted in a cycling rate of approximately 2 cph, an on- period of 6 minutes and an off-period of 24 minutes. In lieu of performing

this cycling test, a manufacturer may use an assigned degradation factor of

Cp = 0.25.

1
For two-speed compressor units, units with two compressors, or units incorporating cylinder unloading, a steady-state test at 62°F (16.7°C) is also

required in order to evaluate the units' performance at this temperature

when cycling on and off at low compressor speed, with a single compressor

in operation, or with a cylinder unloaded.

A frost accumulation test is included and conducted at an outdoor temperature of 35°F (1.7°C) and a relative humidity of approximately 80%. These

conditions are commonly found throughout the country and are also conditions

which can result in large accumulations of frost. At this condition, the

unit is to be tested for a complete defrost cycle, starting and ending at a defrost termination. By testing for a complete defrost cycle, instead of a minimum fixed time interval, units containing a particular frost sensing

control will not be favored over other systems except as they affect the

energy efficiency. For the defrost test, the recommended procedures provide

for a tighter control on the outdoor relative humidity during the heating

period than required by the ASHRAE standard, since it has been determined

from laboratory tests that (depending on the method of defrost initiation)

the performance of some units is related to the outdoor relative huraidity.

Nevertheless, the test should not be significantly more difficult to perform

than the defrost test currently required in the ASHRAE Standard, since test

room tolerances have been relaxed during defrost and for a short time after

the defrosting process is completed.

Because little is known about tht effects of part-load operation on a heat

pump's performance when the unit is operating at conditions which are likely to result in frost build-up, the recommended calculation procedures,

described in section 4, account for the effect of frost formation and

defrosting at outdoor temperatures ranging from 17°F (-8.3°C) to below

45°F (7.2°C) and for the effect of part-load operation for building loads

less than the heat pump capacity. While the separate handling of these

two effects is not rigorously correct, it appears to be a fair and reasonably accurate approach to employ until additional research is carried out

to clarify the interactive nature of these effects.

A low temperature test, similar to the ARI Standard 240-76 low temperature

test condition is also required. Although frost may form on the outdoor

coll the effect on most units' performance at this low temperature condition is not large. Seasonal performance calculations have been made

including and excluding the typical reduction in performance at these low

temperatures due to frost. Comparison of the results indicates that the

accompanying drop in performance which appears in the frost accumulation

test at 35°F (1.7“C) and extrapolated up to 45°F (7 .2°C) tends to couipensate for the exclusion of the performance drop due to frost at the low

temperature. As a result, the effect of omitting a full frost accumulation test at this low temperature has only a small effect on the seasonal

performance. The recommended procedures therefore require a steady-state

test conducted for a duration of 1/2 hour. By not requiring a longer

frost accumulation test (e.g., 3 hours), the test procedures also do not

unfairly favor some units with demand defrost systems which may not

defrost until there is a severe degradation in their performance. Sucli

2
units would tend to be adversely affected by a variety of weather conditions

not accounted for in the proposed test and calculation procedures (such as freezing rain, snow, drifting snow, high winds) which occur in many climatic

regions. While the type of defrost control design, and its reliability and

performance under the above described weather conditions can significantly

affect the seasonal performance of a heat pump, there does not, at the present time, appear to be any easy way of fairly distinguishing between the

performance of different defrost systems at low outdoor temperatures. " Additional research is needed to clarify the important parameters and to develop

defrost test procedures which will encourage manufacturers to install more effective defrost initiation systems.

2. RECOMMENDED TESTING AND RATING REQUIREMENTS

2.1 INTRODUCTION

The heat pump test operating conditions described in Section 2.2.1 through

2.2.5 reflect the various modes of operation a heat pump may commonly

encounter. These operating points were also chosen so as to be able to

estimate the heating seasonal performance with a minimum amount of testing.

Since properly sized heat pumps will cycle on and off to meet small heating

loads, a cycling test is included at an outdoor temperature of 47°F (8.3°C).

The percent on-time for the test was chosen to be 20% in order to maximize

the part-load degradation that would be measured and thereby minimize the

associated experimental error. In order to limit temperature swings inside

the house, it is common practice to design thermostats so that they cause

the unit to cycle at approximately 3 cph at a 50 percent on-time. This

results in a cycling rate of approximately 2 cph at a percent-on-time of

20 percent, which corresponds to cycling period of 30 minutes. The on and

off-times for the cycling test were therefore chosen to be 6 minutes and

24 minutes, respectively.

The results of the cycling tests are used in conjunction with High Temperature Test results to determine a degradation factor.

1. COP^y^(47)

COPss(47)

1 - HLF.

This factor is then used in the performance calculations described in Section 4. Laboratory tests have shown that this degradation factor tends

to be independent of outdoor temperature and, for the purposes of estimating a unit's seasonal performance, may be considered constant over the

range of heating load factors typically encountered in the field.

Manufacturers are given the option of either performing the cyclic test or accepting an assigned degradation factor of = 0.25. It was felt that

this option was necessary in order to accommodate the small manufacturer

3
which might not have test facilities capable of performing the cycling test

within the tolerances required for accuracy.

The steady-state high temperature test at 47°F (8.3°C) and the steady-state

low temperature test at 17°F (-8.3°C) provide the data necessary to define

the instantaneous steady-state capacity and power curves. For outdoor

temperatures equal to or below 17°F (-8.3°C) and outdoor temperatures equal

to or greater than 45°F (7.2°C) the steady-state performance of the unit is

assumed to be identical to that predicted by these performance curves.

Accumulation of frost on the outdoor coil can result in a significant change

in performance over non-frosting conditions. Moreover, frost buildup occurs

in a range of outdoor temperatures and relative humidities for which many

regions of the country can expect many hours of operation. Hence, frost

build-up can have a significant influence on the heating seasonal performance.

To account for this, a frost accumulation test is included and conducted at an outdoor temperature of 35“F (1.7°C) and relative humidity of approximately

80%. The degradation in performance is expected to be significant at this

temperature and relative humidity and the results of this test and the low

temperature test are used to predict the heat pump’s performance under frosting conditions for outdoor temperatures greater than 17°F (-8.3°C) and less

than 45°F (7.2°C). The outdoor relative humidity of 80% was determined to

be an average value commonly occurring in most regions of the country which

have a significant number of hours at outdoor temperatures of 35°F (1.7°C).

The average was determined by weighting the relative humidity found in the

5°F temperature bins occurring between 27°F (-2.7®C) and 37°F (2.8°C)* by

the number of hours in each bin and the number of heat pumps sold. The

results were calculated for 50 regions throughout the continental United

States and averaged.

2 .2 REQUIREMENTS FOR HEAT PUMPS WITH SINGLE-SPEED COMPRESSORS, TWO-SPEED

COMPRESSOR, TWO COMPRESSORS AND COMPRESSORS INCORPORATING CYLINDER

UNLOADING

Heat pumps with single-speed compressors shall be subjected to the following tests, described in Sections 2.2.2 through 2.2.5, respectively:

High Temperature Test at 47°F (8.3°C),

Cyclic Test,

Frost Accumulation Test, and

Low Temperature Test.

As an alternative to performing the cycling test for single speed units,

a degradation factor, Cj^, shall be applied whose value shall be 0.25.

Facility Design and Construction Engineering Weather Data, AFM 88-8

Chapter 6, TM5-785, NAVFAC P-89., Depts of the Air Force, the Army, and

the Navy, Washington, D.C., 1967.

4
Heat pumps with two-speed compressors or two compressors or cylinder

unloading shall be subjected to the following tests, described in Section 2.2.2, 2.2.4 and 2.2.5, respectively:

High Temperature Test at 47°F (8.3°C),

Frost Accumulation Test, and

Low Temperature Test,

with the unit operating on the high compressor speed or with both compressors in operation, or with both cylinders loaded (activated). In addition,

the following tests, described in Section 2.2.2 and 2.2.3, shall be con- ducted :

High Temperature Test at 62°F (16.7°C),

High Temperature Test at 47°F (8.3°C),

Cyclic Test at 47“F (8.3°C),

with the unit operating on the low compressor speed or with the compressor

which normally operates at low loads (high outdoor temperatures), or with

the cylinder that normally operates at low loads (cylinder unloading).

Two-speed compressor, two-compressor, or cylinder-unloading heat pumps, for

which the normal mode of operation requires cycling "on" and "off" of the

compressor at high speed, or simultaneous cycling on and off of both com- pressors or simultaneous cycling on and off of both cylinders, shall also

be subjected to the Cyclic Test at 47®F (8.3°C) described in Section 2.2.3,

with the unit operating on the high compressor speed or with both compressors in operation, or with both cylinders loaded.

An additional requirement for a heat pump with a two-speed coaqjressor or with two compressors or cylinder unloading applies if the unit is designed

to operate on low compressor speed or with a single compressor or a cylinder unloaded at outdoor temperatures below 40“F (4.4°C). If the unit's

low capacity performance at and below 40“F (4.4°C) is needed to calculate

its seasonal performance as specified in Section 4.3, then it shall be subjected to the following additional tests described in Section 2.2.4 and

2.2.5, respectively:

Frost Accumulation Test, and

Low Temperature Test,

with the unit operating on the low compressor speed or with the compressor

which normally operates at low loads or the cylinder which normally operates at low loads (high outdoor temperatures).

In lieu of performing cyclic tests as described in the above requirements, an assigned degradation factor of Cq^~^=0.25 shall be applied for low com- pressor speed (single compressor operation, or one cylinder loaded). Similarly, if a cyclic test is required at high compressor speed (two-compressor

operation, or all cylinders loaded) an assigned degradation factor of = 0.25 shall be used in lieu of performing the cyclic test.

5
2.2.1 General Test Condition Requirements for All Tests

All tests shall be conducted at the indoor-side air quantities specified in

Sections 5. 1.4. 3 and 5. 1.4. 6 and Table 2 of ARI Standard 240-76. Additional sections of this ARI Standard which apply to all tests are:

Voltage and Frequency - Section 5. 1.4.

2

Outdoor-Side Air Quantity - Section 5. 1.4.

4

Requirements for Separated Assemblies - Section 5. 1.4. 5.

For split-system heat pumps, the condenser-evaporator-coil combinations

selected for testing and rating shall be the combination likely to have the

largest volume of retail sales.

For split-system heat pumps, if the indoor portion of the unit is designed

for either horizontal flow or vertical upflow operations, it shall be tested

in the vertical-upflow position.

The equipment under test shall be Installed according to the requirements

of Section 11.2 of ASHRAE Standard 37-69 and Section 5. 1.4. 5 of ARI Standard 240-76. Briefly, this requires that the unit be installed according to

manufacturer's instructions, and with at least 25 feet (7.6 m) of interconnecting tubing (for split systems), no change in external resistance to

air flow to account for barometric changes should be made; pressure gages

should be installed with short lengths of small-diameter tubing; the unit

is to be charged in accordance with the manufacturer's recommended

procedures

.

In all tests, the specified dry-bulb temperature entering the outdoor portion of the unit also applies to the air temperature surrounding the outdoor portion of the unit. Similarly, models where portions are intended to

be installed indoors shall have the air temperature surrounding that portion of the unit the same as the indoor air temperature. Table 1 summarizes the test condition requirements for the different tests.

2.2.2 High Temperature Test Conditions at 47°F (8,3®C) or 62®F (16.7“C)

The steady-state test at 47“F (8.3°C) shall be conducted at an outdoor drybulb temperature of 47°F (8.3°C) and an outdoor wet-bulb temperature of

43"F (6.1°C). The steady-state test at 62®F (16.7“C) shall be conducted

at an outdoor dry-bulb temperature of 62°F (16.7“C) and an outdoor wet-bulb

temperature of 56.5°F (13.6°C). For both tests, the dry-bulb air temperature entering and surrounding the indoor portion of the unit shall be 70°F

(21.1°C) and a maximum wet-bulb temperature of 60°F (15.6°C).

Both tests shall be conducted according to the test procedures outlined in

Section 3.2 for the high temperature steady-state tests. The duration

shall be for a minimum of 1/2 hour. If the unit accumulates frost then the

test shall be preceded by a defrost and tested according to the procedures

outlined in Section 3.2.

6
2.2.3 Cyclic Performance Test Conditions

The cyclic performance test at 47°F (8.3®C) shall be performed immediately

following the High Temperature Test at 47®F (8.3“C). The high temperature

performance test results and the cyclic test results are used together to

find the performance degradation resulting from cyclic operation. The drybulb temperature and wet-bulb temperature of the air entering the outdoor

portion of the unit shall be the same as the high temperature test and the

temperature of the air entering and surrounding the indoor portion shall

also be the same as the high temperature test (70°F (21.1°C) dry-bulb, 60°F

(15.6“C) maximum wet-bulb). The cyclic performance test is conducted according to the test procedures outlined in Section 3.3.

During the cyclic test, the indoor fan shall cycle "on" and "off" as the

compressor cycles "on" and "off", except that the indoor fan cycling times

may be delayed due to controls that are normally installed with the unit.

The compressor cycling times shall be 6 minutes "on" and 24 minutes "off".

As an alternative to performing the cycling tests, a degradation factor, Cj^,

shall be applied whose value shall be 0.25. However, if this alternative is

chosen the high-temperature steady-state test is still required.

2.2.4 Frost Accumulation Test Conditions

The dry-bulb temperature and dew-point temperature of the air entering the

outdoor portion of the unit shall be 35°F (1.7“C) and 30®F (-1.1°C) respectively. The indoor dry-bulb temperature shall be 70°F (21.1°C) and the

maximum indoor wet-bulb shall be 60°F (15.6°C).

Briefly, the frost accumulation test procedures require that the unit undergo

a defrost prior to the actual test. The test then begins at defrost termination and ends at the next defrost termination. Defrost termination occurs when the controls normally Installed within the unit are actuated to cause it

to change from defrost operation to normal heating operation. During the

test, auxiliary resistance heaters shall not be employed during either the

heating or defrost portion of the test.

2.2.5 Low Temperature Test Conditions

The low temperature test shall be conducted at a dry-bulb temperature entering the outdoor portion of the unit of 17°F (-8.3“C) and a wet-bulb temperature of 15.0°F (-9.4°C). The air entering the indoor portion of the unit

shall have a dry-bulb temperature of 70°F (21.1‘*C) and maximum wet-bulb

temperature of 60®F (15.6°C). The test shall be conducted according to the

procedures outlined in Section 3.5.

7
3. HEAT PUMP HEATING PERFORMANCE TEST PROCEDURES

3 . 1 INTRODUCTION

The following steady-state test procedures have been adapted largely from

ASHRAE Standard 37-69. The cyclic performance test procedures have been

adapted from a report entitled "Method of Testing, Rating and Estimating

the Seasonal Performance of Central Air Conditioners and Heat Pumps Operating in the Cooling Mode," NBSIR 77-1271.

The test procedures are categorized as follows:

Steady-State Test Procedure at Outdoor Temperatures

of 47“F (8.3°C) or 62°F (16.7°C) - Section 3.2

Cyclic Performance Test - Section 3.3

Frost Accumulation Test - Section 3.4

Low Temperature Test - Section 3.5

The tests are designed to determine the performance of the unit under conditions of typical use, as well as to establish a performance curve from which

the heating seasonal performance and cost of operation may be determined.

The high temperature test and cyclic performance test are conducted to determine the steady-state and cyclic performance that would typically occur at

high outdoor temperatures.

At temperatures below 45°F (7.2°C), units generally experience a degradation

in performance due to accumulation of frost on the outdoor coil. The frost

accumulation test at 35°F (1.7°C) is designed to account for this effect.

The duration of the test is for a complete cycle from defrost termination

to defrost termination or for a period of time equal to twelve hours, whichever is less. The maximum test time is made long enough so that virtually

all units will be tested for a complete defrost cycle, thereby preventing the

test from favoring one type of defrost control over another.

The low temperature test at 17®F (-8.3°C) is a compromise between establishing a "reasonably accurate" value for the performance and the possible great

expense needed to establish a "true" value. The test Itself is a steady-state

test which lasts for a minimum of 1/2 hour. While frost may accumulate and

affect the performance over a much longer period, the period of time between

defrosts for some units could extend well beyond 12 hours. Other units, however, may have control systems which require them to defrost every 90 minutes.

Both of these defrost control strategies will generally have a small effect

on the heating seasonal performance when the more accurate determination of

performance is obtained by testing from the end of one defrost cycle to the

end of the next defrost cycle. Since the effect on the heating seasonal

performance of neglecting frost formation at low outdoor terapertures has been

calculated to be, in most cases, small and because the effect of requiring

a test from the end of one defrost to the end of the next defrost cycle would

8
place an unfair test burden on some units, a short test period has been

selected in order to obtain the unit's performance under essentially frost

free conditions.

3.2 STEADY-STATE HIGH TEMPERATURE TEST PROCEDURE AT OUTDOOR TEMPERATURES

OF 47"F (8.3^C) OR 62°F (le.?""^

3.2.1 Available Test Methods

Listed below and in the ASHRAE Standard 37-69 are the recommended test

methods for conducting steady-state tests.

i) Air Enthalpy Method - Indoor Side

ii) Air Enthalpy Method - Outdoor Side

iii) Compressor Calibration Method

iv) Volatile Refrigerant Flow Method.

The Air Enthalpy Method - Indoor Side shall be used for all tests. In

addition, one other method chosen from the above list shall simultaneously

be employed as a check on the Air Enthalpy Method - Indoor Side. The

steady-state capacities, as measured by the two methods and calculated

according to the procedures outlined in ASHRAE Standard 37-69, shall agree

within 6 percent in order to constitute a valid test. The results of the

Air Enthalpy Method - Indoor Side shall, however, be the only results

reported and utilized in the heating seasonal performance calculations of

Section 4. Three-piece units and units containing the compressor located

with the indoor section and separately ventilated shall not use a test

method (such as the calorimeter air enthalpy method) which includes com- pressor heat rejection in the determination of heating capacity.

Requirements to be followed in employing the various test methods listed

above as suitable for checking the results of the indoor side air enthalpy

method are given in the ASHRAE Standard 37-69 under the following Sections

subject to the above condition on compressors located Indoors and separately ventilated.

Volatile Refrigerant Flow Method - Sections 5.1 - 5.3 and

5.5

Compressor Calibration Method - Sections 4.1, 4.2.1

(except that only 4 sets of readings are required)

4. 2. 2-4. 2. 6, 4.3, 4.4 and 4.6

Outdoor Air Enthalpy Method - Section 3.1 (except

3.1.3e), 3.2 - 3.5, 3.6.1 (except that the preliminary

and actual tests shall be a minimum of 30 minutes),

3.6.3, 3.7.3, 3.8.2, 3.8.3.

9
3.2.2 Air Flow Rate, Instrumentation and Data to be Recorded

Air Flow Rate. The indoor air flow rate shall be determined as described in

Sections 7.1 through 7.4 of ASHRAE Standard 37-69. In general, this requires

the construction of an air receiving chamber and discharge chamber separated

by a partition in which one or more nozzles are located. The receiving chamber is connected to the indoor air discharge side of the test specimen

through a short plenum. The exhaust side of the air flow rate measuring

device contains an exhaust fan with some means to vary its capacity to obtain

the desired external resistance to air flow rate. The exhaust side is then

left open to the test room or is ducted through a conditioning apparatus and

then back to the test specimen inlet.

The static pressures across the nozzle(s), the velocity pressure and static

pressure measurements measured at the nozzle throat shall be measured with

manometers which will result in errors which are no greater than + 1% of

reading and having a minimum scale division not exceeding 2.0% of the reading. Static pressure and temperature measurements must be taken at the nozzle throat in order to obtain air density. The area(s) of the nozzle(s)

shall be determined by measuring their diameter within an error no greater

than + 0.2% in four places approximately 45 degrees apart, around the nozzle

in each of two places through the nozzle throat, one at the outlets and the

others in the straight section near the radius.

Electrical Measurements . The energy usage of the indoor fan shall be mea- sured with a watt-hour meter which will result in an error which is no greater

than + .5 percent of the quantity measured. Likewise, the energy usage of

the compressor, outdoor fan and all other equipment components (including

controls, crankcase heater, transformers, etc.) shall be measured with a watt-hour meter of the same accuracy.

Indoor-Air Entering and Discharge Temperatures . Measurements of the air temperature entering and leaving the indoor coil or the difference between these

two shall be made in accordance with the requirements of ASHRAE Standard 41

Part 1. These temperatures shall be continuously recorded with instrumentation having a total system accuracy within + .3°F (+ .17°C) and a response

time of 2.5 seconds or less. Response time is defined as the time required

for the instrumentation to obtain 63% of the final steady-state temperature

difference when subjected to a step-change in temperature of 15°F (8.3°C)

or more. Temperature measurements are to be made upstream of the static

pressure tap on the inlet and downstream of the static pressure taps on

the outlet.

Indoor-Side and Outdoor-Side Ambient Conditions . The indoor-side dry-bulb

temperature and outdoor-side dry-bulb temperature shall be continuously

recorded with instrumentation which will result in an error no greater than + .3“F (+ .17°C). In addition, the outdoor wet-bulb temperature or some other suitable measurement from which the test condition wet-bulb temperature

may be derived shall be continuously recorded.

10
Static Pressure Measurements in Ducts . Static pressure measurements in the

ducts and across the unit shall be made in accordance with Section 8 of ASHRAE

Standard 37-69 using a manometer which will result in an error no greater than

+ 0.01 Inches of water (+ 2.5Pa).

Additional Instrumentation and Data Acquisition . All other data not continuously recorded shall be recorded in 10 minute intervals. Additional requirements for instrumentation and data acquisition are listed in Sections 10.1 and

10.2 and Table II of ASHRAE Standard 37-69. Requirements for the volatile

refrigerant flow method are listed in Section 5.2.1, 5.2.2, 5.2.3 of the above

standard. For the compressor calibration method the requirements are found in

Sections 4.2.2 through 4.2.6 of the ASHRAE Standard. Requirements for instrumentation for the Air Enthalpy Method - Outdoor Side are the same as for the

Air Enthalpy Method - Indoor Side.

3.2.3 Test Preparation and Performance

Test chamber requirements are the same as given in Section 11.1 of the ASHRAE

Standard 37-69. When the outdoor air enthalpy method is used the outdoor

chamber must not Interfere with the normal air circulating pattern during the

preliminary test. It is necessary to determine and adjust for system resistance when the outdoor air measuring apparatus is attached to the outdoor

portion of the unit.

The test room apparatus and test specimens must be operated for at least one hour with at least 1/2 hour at equilibrium and at the specified test conditions prior to starting the test. The steady-state test shall then be con- ducted for a minimum of 1/2 hour with intermittant data being recorded at

10-minute intervals. For all units, especially those having controls which

periodically cause the unit to operate in a defrost mode, attention should

be given to prevent defrost during the steady-state test. Units vj'hich have

undergone a defrost should operate in the heating mode for at least 10 minutes after defrost termination prior to the start of the test.

The Air Enthalpy Method - Indoor Side shall be used along with one other

test method listed in Section 3.2 conducted simultaneously. When the outdoor air enthalpy method is used as a second test, then a preliminary test

must be conducted for a minimum of 30 minutes with 4 or more sets of data

recorded at 10-minute intervals. All remaining requirements of Section 3.6.1

in the ASHRAE Standard 37-69 shall then apply in conducting the preliminary

test for the outdoor air enthalpy method.

For some units, at the ambient condition of the test, frost may accumulate

on the outdoor coil. If the supply air temperature or the difference between

the supply air temperature and the Indoor air entering temperature has

decreased by more than 1.5°F (.83“C) at the end of the test, then the unit

shall be defrosted and the steady-state test restarted. Only the results

of this second steady-state test shall be reported and used in the heating

seasonal performance calculation described in Section 4. Alternatively, the

unit may first be defrosted and the steady-state test then conducted. Prior

to beginning the steady-state test, a unit shall operate in the heating mode

11
for at least 10 minutes after defrost termination to establish equilibrium

conditions for the unit and the room reconditioning apparatus. The steadystate test may begin only when the test unit and room conditions are within

the test condition tolerances specified in Table 2.

3.2.4 Test Tolerances

All steady-state tests shall be conducted within the tolerances specified in

Table 2. Variation greater than those given in the Table shall invalidate

the test. The heating capacity results by the indoor air enthalpy method

shall agree within 6 percent of the value determined by any other simultaneously conducted capacity test in order for this test to be valid.

3.2.5 Data Analysis and Results

The results of the steady-state tests shall include:

1) Heating capacity, Qgg(47) or (^Btu/h)

2) Electrical power input to all components, ^^^(47) or Egg(62, (kW)

3) Indoor air flow rate (SCFM) and external resistance to

indoor air flow (inches of water)

4) Outdoor dry-bulb temperature, outdoor wet-bulb temperature

and indoor dry-bulb temperature, (°F)

5) Data to be recorded as specified in Table 11 of ASHRAE

Standard 37-69.

Only the capacity results obtained by the indoor air enthalpy method shall be

reported and used in the calculation procedure described in Section 4. The

formulae to be used in calculating the heating capacity, and the indoor air

flowrate are presented in Sections 3.8.1 and 7.4 of ASHRAE Standard 37-69.

The coefficient of performance obtained for the High Temperature Test, COP,

(47) or COP (62), is the ratio of the heating capacity in kBtu/h to the

product of 3.413 and the sum of the power inputs to the indoor fan in kW

and the power inputs to the remaining equipment components (including aux- iliary power for crankcase heaters, controls, transformers, etc.) in kW.

ss

Units not having an indoor fan as part of the model tested shall add 1.250

kBtu/h per 1000 SCFM (0.78 watts per dm^/s) of Indoor air handled to the

measured capacity to obtain the total heating capacity, 0 (47) or Q ,(62),

and add 0.365 kW per 1000 SCFM (0.78 watts per dm ^/s) of indoor air handled

to the measured power to obtain the total power input, ^^^(47),

to the unit.

or

12
3.3 CYCLIC PERFORMANCE TEST PROCEDURE

3.3.1 Available Test Methods

The cyclic performance test must be carried out immediately following the

steady-state High Temperature Performance Test. This is necessary since the

results of both tests must be used to determine the part-load degradation

factor, Cp, described in Section 3.3.5. The test method for measuring the

capacity during the cyclic operation shall be the indoor air enthalpy method.

No additional simultaneously conducted test method need be employed since the

cycling of the unit tends to invalidate the results. Instead, it is assumed

that the test setup and instrumentation has been proven accurate by the

requirement that the capacities measured by the two test methods, simultaneously employed in the Steady-State High Temperature Test, agree within 6 percent.

3.3.2 Air Flow Rate, Instrumentation and Data to be Recorded

The air flow rate during the on-period of the cyclic test shall be the same (agreement within + 1%) as the air flow rate measured during the previously

conducted High Temperature Test. Data to be recorded and instrumentation

requirements are identical to the requirements of Section 3.2 for steadystate High Temperature Test, where applicable. The instrumentation required

to continuously record the air temperature entering and leaving the indoor

portion of the unit or the difference between these two temperatures shall

have a response time of 2.5 seconds or less. (Response time is defined as the time required for the instrumentation to attain 63% of the final steadystate temperature difference when subjected to a step change in temperature

difference of 15°F or more.) The electrical energy usage of the indoor fan

and the energy usage of the remaining equipment components shall be recorded

with watt-hour meters.

3.3.3 Test Preparation and Performance

The test rooms and equipment installation requirements are identical to the

Steady-State High Temperature Test procedures described in Section 3.2.3. It

is suggested, however, that electric resistance heaters be installed in the

outdoor chamber and indoor chamber where applicable, in order to reduce the

fluctuating heating and cooling loads imposed on the room reconditioning

equipment by the cycling of the test equipment. The indoor-side heater

should be approximately the same capacity as the heating capacity of the

equipment under test. The capacity of the outdoor-side heater should be

approximately equal to the product of the total power input and the quantity

obtained by subtracting unity from the heat pump's COP at 47°F (8.3°C).

The Cylic Performance Test shall follow the Steady-State High Temperature

Performance test, conducted according to the procedures described in Section 3.2. At the conclusion of the High Temperature Test, the unit shall

be cycled "off" and "on", using the "off" and "on" time periods specified

in Section 2.2.3, until steadily repeating ambient conditions are achieved

for both the Indoor and outdoor test chambers, but for not less than two

13
complete "off" /"on" cycles. Without a break in the cycling pattern, the

unit shall be operated through an additional "off"/"on" cycle, during which

the required test data shall be recorded. During the last cycle, which

is referred to as the test cycle, the indoor and outdoor test room ambient

conditions shall remain within the tolerances specified in Table 3.

During the cyclic tests the indoor fan shall cycle "on" and "off" as the

compressor cycles "on" and "off" except that the indoor fan cycling times

may be delayed due to controls that are normally installed with the unit.

The test installation shall be designed such that there will be no airflow

through the Indoor unit due to natural or forced convection while the indoor

fan is "off" by Installing dampers located upstream and downstream of the

indoor portion of the unit.

If, during the preliminary phase of the steady state test the unit underwent

a defrost cycle (either automatic or manually induced) to rid the outdoor

coil of any accumulated frost, then prior to starting the process described

above of cycling the unit "off" and "on" it should be made to undergo a defrost. After defrost is completed and before starting the cycling process

the unit shall be operated continuously in the heating mode for at least

10 minutes to assure that equilibrium conditions have again been established

for the unit and the room conditioning apparatus. Cycling of the unit may

begin when the test unit and room conditions are within the steady-state

test condition tolerances specified in Table 2. For all units, especially

those having controls which periodically cause the unit to operate in a defrost mode, attention should be given to prevent defrost after the cycling

process has begun.

During the off-period portion of the cyclic heating test at 47®F (8.3°C) the

refrigerant switch-over valve shall remain in the heating mode unless the

controls normally supplied with the units are designed to reverse it, in

which case the controls shall operate the valve.

3.3.4 Test Tolerances

The test condition tolerances and test operating tolerances for the on-period

portion of the test cycle are specified in Table 3. Note that the test con- dition requirements in Sections 2.2.2 and 2.2.3 and the test condition toler- ance requirements in Table 2 and 3 require that the average outdoor dry-bulb

temperature measured for the steady-state test and the average outdoor drybulb temperature for the on-period portion of the cyclic test shall be between

46.5®F (8.06°C) and 47.5“F (8.61°C). Similarly, the average indoor dry-bulb

temperatures for the High Temperature Test and the on-period portion of the

Cyclic Test shall be between 69.5°F (20.83°C) and 70.5°F (21.39°C). Variations exceeding any specified test tolerance shall invalidate the test results.

3.3.5 Data Analysis and Results

The actual heating done during the test cycle, in kBtu, shall be determined using the following equation: ^

14
r

1 1000

(3.1)

where

Qcyc(^^) ~ 60

v;(l

^

+ W^)

•/

(time, indoor fan off)

- Tal(0] dt

(time, indoor fan on)

(3.2)

and ^ is the flow rate during the on-period calculated in accordance with

Section 7.4 of ASHRAE Standard 37-69.

For heat pump units tested without an indoor fan, the value determined

above for Qpy«(^7) shall be Increased by a quantity of heat equal to the

product of 1.250 kBtu/h per 1000 SCFM (0.78 watts per dm3/s), the length

of the on-period of the test cycle in hours, and the flow rate of indoor

air circulated in units of 1000 SCFM.

The total energy usage, E^, shall be the sum of the energy usage required

for air circulation during the test cycle and the energy used by the

remaining equipment components (including controls, crankcase heaters,

transformers, etc.) during the test cycle. Units not having an indoor fan

as part of the model tested, shall set the energy required for indoor air

circulation equal to the quantity given by the product of 0.365 kW per

1000 SCFM (0.78 watts per dm^/s), the length of the on-period of the test

cycle in hours, and the rate of indoor air circulated in units of 1000

SCFM.

The cyclic coefficient of performance, COP^ (47) shall be the ratio of the

total heating done in kBtu to the product or 3.413 and the total energy

usage, in kW, when the total heating done and total energy usage have been

adjusted as described above. The cyclic degradation factor shall be calculated as follows:

1 - C0Pcyc(^7)

C0P33(47)

HLF (3.3)

where

HLF Qcyc<^7)

Qss(47) X (tQj^ + ^off)

(3.4)

and Q (47) and COPg^ (47) are the steady-state capacity (kBtu/h) and

coefficient of performance respectively, determined from the Steady-State

High Temperature Performance Test conducted at an outdoor temperature of

47°F (8.3°C) and t^ and t off "on" and "off" times, respectively,

in hours. The degradation coefficient, C^, shall be reported to the nearest .02.

15
3.4 FROST ACCUMULATION TEST PROCEDURE

3.4.1 Available Test Methods

The performance of the unit shall be evaluated using the Air Enthalpy MethodIndoor Side. No other test method need be simultaneously employed, since

the non-steady conditions encountered with equipment undergoing defrost tend

to invalidate the results. In order to assure the accuracy of the instrumentation, the Frost Accumulation Test shall take place after the High Temperature Test has been performed. The requirement that the capacity, as measured

by two simultaneously conducted test methods during the High Temperature Test,

shall agree within 6% is considered proof that test setup and instrumentation

are functioning properly. During the period of time between conducting the

High Temperature Test and the Frost Accumulation Test, modifications shall be

limited to those necessary to conduct the tests and which will have no effect

on the accuracy and precision of the instrumentation.

3.4.2 Air Flow Rate, Instrumentation and Data to be Recorded

The air flow rate shall be the same (agreement within + 1%) as the air flow

rate measured during the previously conducted High Temperature Test. The

instrumentation and data to be recorded shall be identical to the applicable

requirements for the High Temperature Test specified in Section 3.3.2.

The temperature of the air leaving the indoor portion of the unit or the

temperature difference between the entering and leaving air shall be mea- sured in accordance with the requirements outlined in Section 3.2.2. As

mentioned previously, the response time of the above temperature measuring

instruments shall be 2.5 seconds or less when subjected to a step-change in

temperature difference of 15°F or more.

The indoor-side dry-bulb temperature and outdoor-side dry-bulb temperature

shall be continuously recorded with instrumentation having a total system

uncertainty within + 0.3°F (+ 0.17°C). In addition, the outdoor dew point

temperature shall be continuously measured or be determined from other con- tinuously recording instrumentation with an error which is no greater than + 0.5°F (0.28°C). All other data shall be recorded at 10-mlnute intervals

during the heating cycle, except as noted below during defrost.

Defrost initiation, termination and complete test cycle time (from defrost

termination to defrost termination) shall be recorded. Defrost initiation

is defined as the actuation (either automatic or manual) of the controls

normally installed with the unit which cause it to alter its normal heating

operation in order to eliminate possible accumulations of frost on the outdoor coil. Similarly, defrost termination occurs when the controls normally installed within the unit are actuated to change from defrost operation

to normal heating operation. Provisions should be made so that instrumentation is capable of recording the cooling done during defrost as well as the total electrical energy usage during defrost. These data and the continuously recorded data mentioned above need be the only data obtained during

defrost

.

16 V
3. A. 3 Test Preparation and Performance

The test rooms and equipment installation requirements are identical to the

steady-state High Temperature Test procedures described in Section 3.2.3.

The equipment shall be operated according to the manufacturer's recommendation for normal residential use. The defrost controls shall be set at the

normal settings which most typify those encountered in region IV of the

U.S.A. (see Table 5 and Figure 1).

The test room reconditioning equipment and the unit under test shall be

operated for at least 1/2 hour prior to the start of a "preliminary" test

period. The preliminary test period and the test period itself are to be

conducted within the test tolerances given in Section 3.4.4. In some cases,

described below, the preliminary defrost cycle may be manually induced; however, it is important that the normally operating controls govern the defrost

termination in all cases.

For units containing defrost controls which are likely to cause defrost at

Intervals less than one hour when the unit is operating at the required

test conditions, the preliminary test period shall start at the termination

of a defrost cycle which occurs automatically and shall end at the termination of the next automatically occurring defrost cycle. The test period

then begins at the latter defrost termination and ends at the termination

of the next automatically occurring defrost cycle.

For units containing defrost controls which are likely to cause defrost at

intervals exceeding one hour when operating at the required test condition,

the preliminary test period consists of "heating-only" preliminary operation for at least one hour, after which a defrost may be manually or automatically induced. The test period then begins at the termination of this

defrost cycle and ends at the termination of the next automatically occurring defrost cycle. If the unit has not undergone a defrost after 12 hours,

then the test shall be concluded and the results calculated for this 12-hour

period.

For those units which turn the indoor fan off during defrost, the indoor

supply duct shall be blocked during all defrost cycles to prevent natural

or forced convection through the indoor unit. During defrost, auxiliary

resistance heaters which may be normally installed with the unit shall be

prevented from operating.

3.4.4 Test Tolerances

Test condition and test operating tolerances for frost accumulation tests are specified in Table 4. Test Operating Tolerances During Heating applies

when the heat pump is in the heating mode, except for the first 5 minutes

after the termination of a defrost cycle. Test Operating Tolerance During

Defrost applies during a defrost cycle and during the first 5 minutes after

defrost termination when the heat pump is operating in the heating mode. In

determining whether the Test Condition Tolerances are met, only the heating

portion of the test period shall be used in calculating the average values.

17
Variations exceeding the tolerances presented in Table 4 shall invalidate

the test.

3.4.5 Data Analysis and Results

The results to be reported for the Frost Accumulation Test are:

1) Net heating capacity, Qjjgp(35), (kBtu/h)

2) Net electrical power to all components, £^^^(35), (kW)

3) Indoor air flow (SCFM) and external resistance to indoor air flow,

(inches of water)

4) Outdoor dry-bulb temperature, outdoor dew-point temperature and

indoor dry-bulb temperature, (°F)

5) Data to be recorded as specified in Table II of ASHRAE Standard

37-69.

The net heating, QQgj,(35) in kBtu done during the test period shall be

obtained using the equation;

Qt,„( 35) ^ ^

^pa r 1 (3.5)

(.1 + Wj^) 1000

(time, next defrost termination)

where r = j

[T^2 ~ ^al

(time, defrost termination)

The flowrate, in CFM shall be the average of the air flowrates calculated at four or more time intervals throughout the heating phase of the test

using the equations in Section 7.4 of ASHRAE Standard 37-69.

For units tested without indoor fans, the value determined above for Qj^gp(35)

shall be increased by a quantity of heat equal to the product o f 1.250 xBtu/h

per 1000 SCFM (0.78 watts per dm^/s), the length of time in hours during the

Frost Accumulation Test that there was indoor air circulating, and the average flow rate of indoor air circulated in units of 1000 SCFM.

The net heating capacity ,’ (35), is the total net heating done over the

test period (including any credit for the Indoor fan heat) divided by the

total length of the test period, in hours.

The total energy usage, (35) shall be the sum of the energy usage

required for indoor-air circulation during the test period and the energy

used by the remaining equipment components (including controls, crankcase

heaters, transformers, etc.) during the ‘test period. Units not having an

18
indoor fan as part of the model tested, shall set the energy required for

indoor air circulation equal to the quantity given by the product of 0.365

kW per 1000 SCFM (0.78 watts per dm^/s), the length of time in hours during

the Frost Accumulation Test that there was indoor air circulating, and the

average flow rate of indoor air circulated in units of 1000 SCFM.

The net electrical power to all components is the total energy usage

for the test period (including the energy to the indoor fan) divided by the

total length of the test period, in hours.

3.5 LOW TEMPERATURE TEST PROCEDURE

3.5.1

Available Test Methods

The Air Enthalpy Method-Indoor Side shall be used as the primary test method

and the results from only this method used in reporting results. One other

test method, chosen from the list in Section 3.2.1, shall be used simultaneously. The capacity results calculated from the two simultaneously conducted

tests must agree within 6% in order to constitute a valid test. The requirements and applicability of the test methods are described in Section 3.2.1.

When the air-enthalpy method is employed for the outdoor side tests, it is

important to determine whether attachment of an air flow measuring device

affects the performance. A preliminary test shall be conducted according to

the requirements specified in Section 3.6 of ASHRAE Standard 37-69, except

that the test duration shall be 1/2 hour and only four sets of readings are

required. In addition, the preliminary test shall start shortly after a defrost termination (either induced manually or occurring automatically) in

a manner similar to that described in Section 3.2.3 for the High Temperature

Test.

3.5.2 Instrumentation and Data to be Recorded

Where applicable, instrumentation and data to be recorded are identical to

the High Temperature Test described in Section 3.2. Intermittently acquired

data shall be recorded at 10-minute intervals.

3.5.3 Test Preparation and Performance

Where applicable, the Steady-State High Temperature Test test preparation

and performance requirements shall also be used in the Low Temperature Test,

except where noted below. The test room and reconditioning equipment shall

first be operated in a steady-state manner for at least one half hour at

equilibrium and at the specified test conditions. The unit shall then undergo a defrost, either automatic or manually induced. It is important, however,

that the unit terminate the defrost sequence by the action of its own defrost

controls. At a time no earlier than 10 minutes after defrost teraunation, the

test shall start. The test duration is one half hour. For all units, especially those having controls which periodically cause the unit to operate in

a defrost mode, attention should be given to prevent defrost during the onehalf hour test period.

19
3.5.4 Test Tolerances

During the test period for the Low Temperature Test, the operating conditions shall be within the tolerances specified in Table 2.

3.5.5 Data Analysis and Results

Data analysis and results are the same as those described for the SteadyState High Temperature Test in Section 3.2.5. The heating capacity and

indoor air flow rate are calculated using the appropriate equations presented in Sections 3.8.1 and 7.4 of ASHRAE Standard 37-69. Units tested

without indoor fans shall have 1.250 kBtu/h per 1000 SCFM (0.78 watts per

dm^/s) of indoor air handled added to their measured capacity to obtain their

total heating capacity, Qgg(17), and shall have 0.365 kW per 1000 SCFM (0.78

watts per dm-^/s) of indoor air handled added to their measured power to

obtain their total power input, ^^^(17). The total power input includes power

to the indoor fan and all remaining equipment components (including controls,

crankcase heaters, transformers, etc.)

4. CALCULATION OF THE HEATING SEASONAL PERFORMANCE FACTOR (HSPF) AND

SEASONAL COST OF OPERATION

4.1 INTRODUCTION

The heating seasonal performance factor, HSPF, and seasonal operating cost of

a heat pump are strongly dependent upon the climatic region in which the

heat pump operates, the type of heat pump system employed (e.g., single-speed

or variable-speed compressor, whether the compressor operates at all temperatures or is turned off and on at certain temperatures, etc.), and the heating

requirement of the building relative to the unit's capacity at different

outdoor temperatures. Because of these factors, it is recommended that the

HSPF and seasonal cost of operation of a heat pump be calculated between

the ranges of the maximum and minimum "design heating requirement" in each

major climatic region of the country using the temperature bin method. A

"design heating requirement" is the heating requirement that must be met by

the heat pump system at the 97-1/2 percent outdoor design temperature. In

addition, a consumer purchasing a heat pump which provides both heating and

cooling should be reminded to select a cooling capacity which will satisfy

his home's cooling requirements and maintain a comfortable Indoor level of

relative humidity .

The heating load hours (HLH) for a specific geographical region are determined by using the following expression:

HLH 24 X D-D (4.1)

where D-D and T^^ are the number of degree-days and outdoor temperature

("F) respectively for the region. The number of heating load hours was computed for many regions of the country, resulting in the plot presented

20
in Figure 1 . Standard values of the number of heating load hours and the

outdoor design temperatures were developed and are presented in Table 5.

The general procedure for estimating the seasonal operating cost of heat

pumps is to first calculate the heating seasonal performance factor (HSPF)

for the heat pump for the desired geographical region. The seasonal heating required is next determined and is equal to the product of the number

of heating load hours (HLH) for the region, the design heating requirement

(DHR) and a correction factor equal to 0.77. The correction factor, based

on experience, improves the agreement between calculated and measured

building loads. The seasonal operating cost is then determined by the

product of the seasonal heating required and the fuel (electricity) cost

divided by the HSPF. This calculation has the advantage of allowing direct

comparison of the seasonal operating cost of heat pumps and furnaces, since

the latter is calculated in a similar manner.*

4.2 CALCULATING THE HSPF AND SEASONAL OPERATING COST FOR HEAT PUMPS WITH

SINGLE-SPEED COMPRESSORS

Table 5 lists six major U.S. climatic regions and their associated heating

load hours, outdoor design temperatures, and fractional hours in each

temperature bin. Figure 1 is a map of heating load hours (HLH) for the

continental United States that may be used to locate these six regions.

The minimum and maximum design heating requirements of a residence in which

a heat pump is likely to be installed will depend upon the climatic region

and the capacity of the unit. They may be obtained for each of these six

climatic regions by using the following equations:

minimum design

heating requirement

for regions I, II, III,

IV, and VI

(4.2)

Oss(^^)» region V

and

maximum design

heating requirement

2 Qss(^7),

60

for regions I, II, III,

and IV

(4.3)

2.2^Ss(^^)» region V

* Recommended Testing and Calculation Procedures for Determining the

Seasonal Performance of Residential Central Furnaces and Boilers;

Kelly, Chi, Kuklewicz; NBSIR 78-1543, National Bureau of Standards,

Oct. 1978.

21
and rounding the results off to the nearest standardized design heating

requirement given in Table 6. In the above equations, is the outdoor

design temperature given in Table 5 for each major climatic region and

Qss(^7) is the heat pump capacity measured during the high temperature

performance test at 47°F.

For each climatic region and for all standardized design heating requirements (see Table 6) ranging from the minimum to the maximum design heating

requirements for the region, the heating seasonal performance factor, iiSPF

and seasonal operating cost of a heat pump shall be determined using:

HSPF

T "-i ^ ^ BL(T.)

J N j

(3.413)

\z ^

U N

X(T.)

PLF(X)

6(Tj) E(Tj) + 3

RH(T

fT

> (4.4)

and

Seasonal (HLH) (C) (Design Heating Requirement) (Cost per KWH in $*s).

Operating = ——— (4.5)

Cost (3.413)(HSPF)

where

j = 1, 2, 3, , n corresponds to the j temperature bin

n = total number of non-zero temperature bins in the climatic region

Tj = 67 - 5j is the representative temperature of the bln, „(°F)

L = indicates the quantity following the symbol is to be summed over

j all temperature bins , RH(Tj)

N

supplementary resistance heat term at temperature Tj required in

those cases where the heat pump automatically turns off (T-j^ToN^ or when it is needed to meet the balance of the building heatxng

requirements, (kW)

l_ 1. is the number of hours in the j temperature bin divided by

N = nj and is referred to as the "fractional hours in ^ temperature bln"

HLH = is the number of heating load hours for the region as given in

Table 5, (h)

22
DHR = is the design heating requirement (kBtu/h)

3.413 = is a conversion factor which converts kilowatt hours to kBtu

Tqjj = is the outdoor design temperature given in Table 5 for each

major climatic region, (“F)

C = 0.77 is an experience factor which tends to improve the agreement between calculated and measured building loads*

BL(Tj) = building load at temperature Tj, (kBtu/h)

fi(Tj) = heat pump low temperature cut-out factor

X(Tj) = heat pump heating load factor

PLF(X) = heat pump part-load factor

The quantities BL(T.), *S(T.), X(T-), PLF(X) and are defined by the

following equations: J J

(C)(DHR) (4.6)

«(Tj) =

X(T.) =

PLF(X) =

^ 0 ;

V

BL(Tj)

Q(Tj)

1

Q(T.)

Tj < Tqff

/ -J

* "^OFF ^ Tj < Ton

(3.413)(E(Tj))

Q<^j>

(3.413)(E(Tj))

Q(T.)

Tj ^ Ton —

(3.413)(E(Tj))

0(Tj) > BL(Tj)

^(Tj) < BL(Tj)

1 - Cp(l - X(TO)

< 1

> 1

> 1

(4.7)

(4.8)

(4.9)

ibid.

23
(4.10)

RH(T.)

^ — [BL(ip - Q(T.) X(T.) 6(Tj)]"^

jrm

where

OFF

'ON

= the outdoor temperature that the compressor is automatically

shut off (If no such temperature exists, T. is always greater

than T_ and , (°F) OFF

the outdoor temperature that the compressor is automatically

turned on (if applicable) if designed for low temperature

automatic shut-off, (°F)

= degradation factor determined as described in section 3.3.5.

In using the above equation to calculate HSPF , the heat pump capacity in

kBtu/hr, Q, and the power in kW, fi, shall be obtained as follows:

Q(Tj) =

E(Tj) .

Qssd?) +

30

i 3~

Qss( 17) +

~ ~ 17°F < Tj < '^5°F

(Egg(47) - E SS

18

(|7))(Tj - 17)

30

(Epgp(35) - Egg(17))(Tj - 17)

18

-

45°F or Tj < 17'

(4.12)

17°F < T. < 45®F

where and E^^(47), Q (35), and E|^p.^(35), and Qgg(17) and £^^(17)

are the capacities ^?n kBtu/Sr^ and powers ^fn kW) measured during the high

temperature test, the frost accumulation test, and the low temperature

test, respectively. For units not incorporating an indoor fan as part of

the model, the above measured capacities and power inputs are to be adjusted

as described in Sections 3.2.5, 3.3.5, 3.4.5, 3.5.5. The above measured

power Inputs include indoor fan power, compressor and outdoor fan power to

all other remaining equipment power svich as controls, crankcase heaters,

transformers, etc. It should be noted that if the above definition of

0(Tj) and E(Tj) result in the quantity Q(T j) less than unity for a (3.413)(E(Tj)

temperature T., then the value of 6 (T^ used in the above HSPF calculation

is equal to zero at this particular temperature T.. This is done to avoid

the possibility that any errors. Introduced by th^ straight line extrapolation of the measured capacities and power inputs to low outdoor temperature,

could cause the heat pump to have a COP which is less than unity.

24
Appendix A presents example calculations for the heating seasonal performance

factors and seasonal operating costs corresponding to the range between

maximum and minimum design heating requirements for one of the six regions,

specified in Table 5. It is recommended that all seasonal operating cost

figures be rounded off to the nearest five dollars and the information be

arranged in a form similar to Table 7 to assist the consumer in selecting the

most cost-effective heating appliance for his residence.

If a single HSPF and a single seasonal operating cost figure is required for

labeling purposes, it is recommeded that the HSPF corresponding to Region IV

and the standardized design heating requirement nearest the capacity measured

during the high temperature performance test, <^ 53 (^ 7 ), be used and that the

operating cost be based upon this HSPF and on a value of HLH equal to 2080.

It must be pointed out, however, that the use of a single HSPF and a single

operating cost figure, without a breakdown by region or design heating

requirement, will mislead the consumer . A heat pump which is the best performing unit in one climatic region will not necessarily be the best performer

in another climatic region. In addition, since the performance of a heat

pump is so dependent upon the climatic region and the design load, a fair and

accurate comparison with electric and fuel-fired furnaces or boilers is

impossible without a breakdown similar to the one given in Appendix A.

4.3 CALCULATING THE HSPF AND SEASONAL OPERATING COST FOR HEAT PUMPS WITH TWOSPEED COMPRESSOR OR TWO COMPRESSORS, OR COMPRESSORS INCORPORATING

CYLINDER UNLOADING

The minimum and maximum design heating requirements of a residence in which

a heat pump is likely to be installed shall be determined for the six climatic regions listed in Table 5 using the same procedure outlined in Section

4.2 for units with single-speed compressors. The only difference is that

^Ss'^ '(47) (which is the capacity measured in the high temperature performance test at 47°F (+8.3°C) with the unit operating at the high compressor

speed or with both compressors in operation or with all cylinders in operation) shall be used in place of ^ 53 ( 47 ) in equations 4.2 and 4 . 3 .

For each climatic region and for design heating requirements ranging from

both the minimum and maximum design heating requirements for each region,

the heating seasonal performance factor, HSPF, and seasonal operating cost

of a heat pump shall be determined using:

HSPF =

(3.413)

Z ^1

j ir^L(T.)

Z E(Tj) ^

RH(T.)

j N j N

(4.13)

25
and

Seasonal

Operating

Cost

(HLH) (C) (Design Heating Requirement) (Cost per kWh in $'s)

(3.413)(HSPF)

where T . 3'. n

J 3.413, BL(Tj), C, j, have been previously defined.

(4.14)

The terms PLf’^ PLF^ are consistent with the

N

definition for single-speed heat pumps and are expanded to include highspeed or two-compressor operation or both cylinders in operation (k=2) or low-speed or single-compressor operation or a cylinder unloaded (k=l).

These terms along with the term (denoting the heat pump electrical

N

energy usage in the temperature bin divided by the total number of bin

hours) are evaluated according to the four possible cases of heat pump

operation denoted below.

CASE I

*k=l BL(T.) Q (T-); and the unit is operating at low compressor speed or with

a single compressor or with a cylinder unloaded, i.e., k=l, for which the

building heating load, BL(Tj) is less than or equal to the heating capacity,

(^k-l(Tj).

E(Tj)

_ Ek'l(Tj) xk=l(Tp «'(Tp n,

T ’ tr

n

BL(T^[1 - e'(T.)]

N 3.4i3i

(4.15)

(4.16)

k=l BL(T.)

^ <Tj) = l(Tj)

PLF^ ^ = 1 - c^^ (1 - X’: ) k=l k=l

6’(Tj) =

0

1/2

1

Tj 1 Tqpp

^OFF ^ - ^ON

(4.17)

(4.18)

(4.19)

26
CASE II

^k-l(T

) < bL(T.) < Q^~^(Tj); and the unit is alternating between high-speed

or two-compressor operation or with both cylinders loaded (k=2) and low-speed

or single-compressor operation or a cylinder unloaded (k=l) to satisfy the

building heating load at temperature

E(T.)

_ [gk-l(T^)xk-l(Tj) + E’^"2(Tj) X^ ^(Tj)] 6’(Tj)

N

^

(4.20)

RH(Tj) ^ BL(Tj)[l - 6'(T.)]

_ (4.21)

N 3.413

V-1 _ Q^=2(t^) - BL(Tj)

qk=2(Tp _ Qk=l(xj)

^(Tj) (4.22)

= 1 - X^"^(Tj) (4.23)

1

0 ; Tj <. Tqpp

«S’(Tj) =

1 1/2 ; Tqpp - '^ON (4.24)

CASE III

0

~ (T-) < BL(T.) < and the unit is cycling on and off at high

compressor speed or cycling both compressors on and off simultaneously, or both cylinders cycling on and off simultaneously, (k=2) in order to satisfy

the building heating load at temperature T

^k=2,

N

PLFk=2 ( 4 . 25 )

RH(T.)

N

BL(Tj)[l - 6'(T^]

3.413 ( 4 . 26)

xk=2(T^) = BL(Tj)

Q^"^(Tj)

( 4 . 27 )

27
PLF^“^ = 1 - C (4.28) ^

2 (1 _ ^(T.))

6*(Tj) =

0 ;

1/2 ;

1 ;

'OFF

1 ^OFF

< Tj <

Tj > Ton

(4.29)

CASE IV

BL(T.) ^ Q^~^(T^); and the unit operates continuously at high compressor

speed or with both compressors in continuous operation or with both cylinders loaded (k=2) in order to satisfy the building heating load at temperature Tj.

E(T ) -2

E^"^(Tj) ^(Tj) 6"(Tj) ^

(4.30)

n. RH(T^)

^ [BL(Tj) - Qk=2(Tj) xk=2(T^) 6"(Xj)] ^

N 3.413

(4.31)

X^"^(Tj) = 1.0

r 0 ; Tj < Toff

Qk=2(T ) (3.413)(E’^"^Tj))

< 1

j ; Toff < Tj < Ton ^^d — > i (3.413)(E’^"2(Tj))

nk=2

V

' ’ Tj > Ton

(T.)

(3.413)(E’^"^(Tj))

> 1

(4.32)

In each of the above cases, the heating capacity in kBtu/h, ^Tj) and

• k

.

the power input in kW, E (T.), corresponding to low speed, single com- pressor operation, or unloaded cylinder (k=l) and high speed, two com- pressors in operation, or all cylinders loaded (k=2) , shall be calculated

(when required) as follows:

28
^SS 15

Q^ \xj) =^^1*^-1 Q^-M17) .

,.k=l

ssvl?)) (T. - 17 ) 18

Ak=l,.,^ . <Qss^( 47) - C\l7» (T. - 17)

V. SS 30,

T > 40°F (4.34a)

J -

17°F < T. < 40°F (4.34b)

- 3

Tj < 17°F (4.34c)

•k=2, X - Qss^(17)) (T. - 17)

'Q*^ ^(17) + J ; T. > 45°F or

SS 30

Ak=2,,,, . (QdEf(35) - (17)) (T, - 17)

‘^SS 18

'±

3 -

T. < 17°F

3 -

17°F < T. < 45°F

3

(4.34d)

(4.34e)

^Fk=l,/..^ . (^8^(62) - Es^(^7)) (T. - 47)

SS 15

l(Tj) fk=ln 7 ^ . (EdEf( 35) - Es;\l7)) (T; - 17)

SS 18

^k=ln7^ . (^sr(^7) - 4^(17)) (Ti - 17)

V SS 30

T. > 40°F

3 -

17°F < T. < 40

- 3

T. < 17°F

3

(4.35a)

(4.35b)

(4.35c)

E^~2(Tj)

^k=2,,7^ . (^Sr(^7) - E^;^17)) (T. - 17)

SS 30

^k=2n7'» + (^DEf(^^^ ^SS (17)) (T^ - 17)

SS 18

T. > 45°F or (4.35d)

3 -

T. < 17°F

3 -

17°F < T. < 45°F (4.35e)

k k k k k k

where 033 ( 62 ) and Egg(62), ^ 33 ( 47 ) and Egg(47), Qdef( 35) and Ep£p(35),

k k

and ^33 ( 17 ) and Egg(17) are the capacities (in kBtu/hr) and power (in kW)

measured during the high temperature tests at 62°F, the high temperature

tests at 47*’F, the frost accumulation tests, and the low temperature tests,

respectively. For units not incorporating an indoor fan as part of the

model the above measured capacities and power inputs are to be adjusted as described in Sections 3.2.5, 3.3.5, 3.4.5, 3.5.5. The above measured power

inputs include indoor fan power, compressor and outdoor fan power and power

29
to all other remaining equipment components such as controls, crankcase

heaters, transformers, etc. It should be noted that if these definitions of

«k ok=2/T' \ Q*'^(Tj) and E (Tj) result in the quantity ^

(3.413)(e‘^"2(Tt))

being less than

unity for a temperature T., then the value of 6"(T.) used in the above HSPF

calculation is set equal to zero at this particular temperature T.. This

avoids the possibility of having a COP for the heat pump at an outdoor temperature T. which is less than unity because of any errors introduced by the

straight line extrapolation of the measured capacities and power inputs to

low outdoor temperatures.

In the four cases described above, and Tqjj are, respectively, the outdoor temperatures at which compressor operation automatically stops and automatically starts. If no such temperatures exists, then T. is always greater

than Tqjj and Tq^j,. The quantity is the part-load degradation factor

for the unit cycling at high compressor speed or with both compressors simultaneously cycling or both cylinders simultaneously cycling (if applicable) and

is the part-load degradation factor for unit cycling at low compressor

speed or with the single compressor or single cylinder that normally operates

at low heating loads (high outdoor temperatures).

Appendix B presents an example to aid in calculating the heating seasonal performance factors and seasonal operating costs for a range of design heating

requirements from the minimum to the maximum (standardized according to the

values given in table 6) for one of the regions specified in Table 5. It is

recommended that all seasonal operating cost figures be rounded off to the

nearest five dollars and the information be presented in a form similar to

Table 7 to assist the consumer in selecting the most cost-effective heating

appliance for his residence.

If a single HSPF and a single seasonal operating cost figure is required for

labeling purposes, it is recommended that the HSPF corresponding to Region

IV and the standardized design heating requirement nearest the capacity, Q^“

(47), (measured during the high temperature performance test at 47"F with

the unit operating at the high compressor speed or with both compressors in

operation or both cylinders in operation) be used. The operating cost shall

then be based upon this HSPF and a value of HLH equal to 2080. It should

be pointed out, however, that the use of a single HSPF and a single operating

cost for heat pumps with two speed compressors or two compressor speeds or cylinder unloading compressors has the same draw backs as those discussed in

section 4.2 for units with single-speed compressors.

30
Table 1.

Suinniary

of

Test

Requirements

bO CO a Qi •H »-l a 3

•H '3

(0 (U U U

l-i

O CO 'd' CM • • • Oi (X| • CO CO CO

CO

a 4J O CO •H (U +J H O3 O

c/5 4J

CO iJ

O 3 CO '3- <o

4J (U CM • • • a • CM CM CM

a 00 (u CM • • • o a >-i • CM CM CM

•H *H *H CM

•U 3 3 A

A o -H cr A 1 ( rH

(U n) (u 1-H • • • V3 4-1 Pi • CM CM CM u CM • • • OJ 4-1 • CM CM CM

CLi CO CM

(U H

<4-4

<4-1 3 o m O 1 CM •H 3 • •H O 3 3 3 (U 0 iH 4J o 4J II 3 3

•H 3 4J

4J CM

Q 3 a CO ^ O 3 1 •H 1 3 O Ss

>1

O 3 3 33 o •3 3

CO 3 3 i 4J 3

(V 3 •HM 3 4J

Q 4J 0 COO CO

Cfl

M

vO

b

m• b CO vO CO

O lO 0 sf m 'Cf CO f-H

II II II II II E9 e b kl « s s 5 Q O CO H H H H H O 3 A A A •f -o o ^1 CM c- m 4.) *H Mt o vO CO i-H 3 4-' II II II II II O -H OQ PQ 33 33 PQ 73 Q Q Q Q Q 3 T T H H H ou 3O 3 •H U .-1 CM 4-1 3 3 3 (H

4-) 3 3 t—1 3 3 O O 3 4-1 h •H -H 0 3 3 4J 4J 3 M

0-

a cx 3 3

4J 0 o o CJ &>

CO 3 <J 0

<U

H o 3 H •H 4-1 H X r—1 U

W)

O

O

•H »-l

O

33 CD

b i-J • • • • f-H CM CO

31
Table 2 . Steady-State High Temperature and Low Temperature Test Tolerances

Indoor dry-bulb, ®F

Entering

Leaving

Indoor wet-bulb, “F

Entering

Leaving

Outdoor dry-bulb, “F

Entering

Leaving

Outdoor wet-bulb, “F

Entering

Leaving

Test Operating*

Tolerance

Test Condition**

Tolerance

2.0 0.5

2.0

1.0

1.0

2.0 0.5

2.0

1.0 0.3

1.0

External resistance to air

flow, inches of water .05 .02

Electrical voltage, % 2.0

* Test Operating Tolerance is the maximum permissible variation of any measurement. When expressed as a percentage, the maximum allowable variation is the

specified percentage of the average value.

** Test Condition Tolerance is the maximum permissible variation of the average

value of the measurement from the standard or desired test condition.

32
Table 3 Test Tolerances for the On-Period Portion of Cyclic Performance Tests

Test Operating Tolerances* Test Condition

(Applies after the 1st 30 Tolerance** sec. after compressor

start-up)

Indoor dry-bulb, ®F

Entering

Leaving

Indoor wet-bulb, ®F

Entering

Leaving

Outdoor dry-bulb, “F

Entering

Leaving

Outdoor wet-bulb, ®F

Entering

Leaving

External resistance to air-flow,

inches of water

2.0

1.0

2.0

2.0

.05

Electrical voltage, % 2.0

0.5

0.5

1.0

.02

* Test Operating Tolerance is the maximum permissible variation of any measurement. When expressed as a percentage, the maximum allowable variation is

the specified percentage of the average value.

** Test Condition Tolerance is the maximum permissible variation of the average

value of the measurement from the standard or desired test condition.

33
Table 4. Test Tolerances for Frost Accumulation Tests

* Testing Operating Tolerance Test Condition Tolerance

During Heating During Defrost (Heating Portion Only)

Indoor dry-bulb, “F

^ 4r Entering 2.0 4.0 0.5

Leaving

Indoor wet-bulb, “F

Entering 1.0

Leaving

Outdoor dry-bulb, °F

Entering 2.0 10.0 1.0

Leaving

Outdoor dew-point, °F

Entering 1.5 0.7

Leaving

External resistance to

air-flow, inches of water .05 .02

Electrical voltage, % 2.0

t Test Operating Tolerance is the maximum permissable variation of any

measurement. When expressed as a percentage, the maximum allowable

variation is the specified percentage of the average value. Test

Operating Tolerance During Heating applies when the heat pump is in

the heating mode, except for the first 5 minutes after termination of

a defrost cycle. Test Operating Tolerance During Defrost applies

during a defrost cycle and during the first 5 minutes after the termination of a defrost cycle when the heat pump is operating in the

heating mode.

Test Condition Tolerance is the maximum permissable variation of the

average value of the measurement from the standard or desired test

condition. Test Condition Tolerance applies only when the heat pump

is operating in the heating mode.

Not applicable during defrost if the indoor fan is off. j

34
Table 5. Major Climatic Regions In The Continental U.S.A

Region I II III IV V VI

Heating Load Hours, HLH 750 1250 1750 2250 2750 2750*

Outdoor Design Temperature,

Tqp for the region 37 27 17 5 -10 30

Fractional Hours:

Bin // 1

H

o

j = 1 62 .291 .215 .153 .132 .106 .113

2 57 .239 .189 .142 .111 .092 .206

3 52 .194 .163 .138 .103 .086 .215

4 47 .129 .143 .137 .093 .076 .204

5 U2 .081 .112 .135 .100 .078 .141

6 37 .041 .088 .118 .109 .087 .076

7 32 .019 .056 .092 .126 .102 .034

8 27 .005 .024 .047 .087 .094 .008

9 22 .001 .008 .021 .055 .074 .003

10 17 0 .002 .009 .036 .055 0

11 12 0 0 .005 .026 .047 0

12 7 0 0 .002 .013 .038 0

13 2 0 0 .001 .006 .029 0

14 -3 0 0 0 .002 .018 0

15 -8 0 0 0 .001 .010 0

16 -13 0 0 0 0 .005 0

17 -18 0 0 0 0 .002 0

18 -23 0 0 0 0 .001 0

In Pacific Coast Region

35
5

10

15

20

6. Standardized Design Heating Requirements (kBtu/h)

!

25 50 90

30 60 100

35 70 110

40 80 130

36
Table 7. Example of Information Which Would Assist A

Consumer in Purchasing A Heating Appliance

Cooling Capacity at 95“F = * * * * (if applicable)

Heating Capacity at 47“F = 36,000 Btu/h

Design

Heating Cost of Fuel ($/kWh)

Requirement

Region (kBtu/h) HSPF .02 . .04 .06 .08 .1

I (750 HLH)15

20

25

30

35

il

(1250 HLH)

25

30

35

40

50

III

(1750 HLH)

30

35

40

50

60

IV*

(2250 HLH)

35

40

50

60

70

V*

(2750 HLH)

35

40

50

60

70

80

VI*

(2750 HLH in

Pacific Coast

Region)

20

25

30

35

40

Manufacturers should be given the option of stating that "This heat pump

is not recommended for use in this region" or some equivalent phrase.

37
2500

38

This

map

is

reasonably

accurate

for

most

parts

of

the

United

States

but

is

necessarily

highly

generalized,

and

consequently

not

too

accurate

in

mountainous

regions

partcularfy

in

the

Rockies
APPENDIX A

Sample Calculations for a Single-Speed Compressor Heat Pump

The following sample calculation for a single-speed compressor heat pump

Illustrates the type of experimental data required and the use of the tables

in calculating the HSPF and seasonal cost of operation for different regions

of the country. The performance data and mode of operation has been contrived to illustrate the calculation procedure and is not meant to be representative of typical or desired operational characteristics.

The experimental data required in the recommended test procedures is presented in Table A1 for the fictitious single-speed compressor heat pump.

It is assumed that the manufacturer has chosen to exercise the option of

using a value of 0.25 for the degradation factor, C^. (It should be noted

that in lieu of employing an assigned value of Cjj the manufacturer has the

option of performing the cyclic performance test described in section 3.3.)

The heat pump is designed to stop operation at an outdoor temperature, T^^p

equal to 5®F. It is assumed that the heat pump will start operating when

the temperature Increases to a value of Tq.^ equal to 12“F. During the time

the heat pump is not operating or not providing sufficient heating capacity

to meet the building heating load, supplementary electric resistance heaters

will supply the balance of the heating requirements.

Table A2 is a sample worksheet used to evaluate the HSPF and seasonal cost

of operation. The HSPF and operating cost is to be evaluated for a geographic location encompassed by Region V (see Table 5 and Figure 1). The

heating load hours, HLH, and outdoor design temperature, T^^, obtained from

Table 5 are 2750 hours and -10®F, respectively.

The HSPF and seasonal cost of operation are to be calculated for the geographic region for a minimum design heating requirement, DHR^^^. This minimum

value corresponds to the smallest design building load that a particular

heat pump is likely to encounter in most practical applications. Equation

4.2 along with the capacity data from Table A1 is used to calculate a DHR^^^

of 50 (kBtu/h) when standardized to the values presented in Table 6.

Columns (a) and (b) of the sample worksheet. Table A2 , contain fixed numbers

representing the temperature bln number, j, and the corresponding representative outdoor temperature, T. in *F. The fractional bin hours, are obtained for Region V from the data presented in Table 5. N

In the following outline, examples are given to illustrate the use of the

equations employed to fill in the remaining columns of the worksheet in

Table A2 and arriving at a value of the HSPF and seasonal cost of operation.

Column d ; Building Load

The building load is calculated for each representative outdoor temperature,

Tj, by equation 4.6.

39
Example:

BL(42) =

Tj = 42“F

65 - T. 65 - T

(C)(DHR)

OD

65 - 42 (.77)(50)

65 + 10

= 11.807 (kBtu/h)

Columns (e) and (f): Capacity and Power Input

The heat pump capacity Q(T.) and power input, E(T-) are determined from

equations (4.11) and (4.12;, respectively, and the experimental data presented in Table A1

.

Example ; T^ = 52°F

Q(52) = Q(17) +

[Qss( 47) - Qgg(17)](52 - 17)

30

[48.00 - 30.001(52-17)

= 30.00 + = 51.00 (kBtu/h)

30

Example : Tj = 37“F

Q(37) = Q(17) +

[Qdef(35) - Qsr(17)](37 - 17)

'SS

18

(36.00 - 30.00)(37 - 17)

= 30.00 + = 36.67 (kBtu/h)

Column g: Heating Load Factor

The heating load factor, X(Tp, is evaluated by equation (4.8) using the

values from columns (d) and (e);

Example ; T^ = 27“F

X(27) _ BL(27) _ 19.505

qTIT) 33.33

.585

Column (h): Part Load Factor

The part-load factor PLF(X) is evaluated by applying equation (4.9), the

data from Table A1 , and values from column (g).

40
Example ; = 47“F

PLF(X) = 1 - Cjj(l - X(Tj))

= 1 - 0.25 [1 - .193] = .798

Column (i); Low Temperature Compressor Cut-Out Factor

The low-temperature compressor cut-out factor, 5(T.), is evaluated for

each representative outdoor temperature T. by equation 4.7 and the

Tqpp = 5°F, = 12'F. ^

Example ;

6(17) = 1

Example ;

6(12) = ^

Tj = 17“F

Tj = 12®F

Example ; = 2°F

6 ( 2 ) = 0

Column (j); Heat Pump Electrical Energy Input

The heat pump electrical energy input for each temperature bin, j, is

represented by the terms within the first summation sign in the denominator

of equation (4.4), rewritten here for convenience:

ti. X(T^) 6(Tj)E(Tj)

F" plf(x)

Using Table A2, the above expression may be evaluated as follows:

(Col. j) = (Col. c)(Col. g)(Col. l)(Col. f)

(Col. h)

Example : T^ = 12“F

(Col. j) = ilPA?.) a)(0-5)(4-290) , .1008

Column k: Supplementary Resistance Heat

The supplementary resistance heat, ^^(Tj)

^ evaluated by using

equation 4.10. N

41
Example ; = 12“F

RH(12) _ [BL(12) - Q(12) X(12) 6(12)] "j

N 3.413 N

_ [27.205 - (27.00)(1)(0.5)] (.047) ^

Column 1: Heating Load

The heating load at each temperature bin, j, is represented by the term

within the summation sign in the numerator of equation 4.4, written as ^

BL(Tj).

Example ; Tj = 12°F

(Col. 1) = (Col. c)(Col. d) = (.047)(27.205) = 1.2786 [kBtu/h]

Equation (4.4) is evaluated for the HSPF by summing the values in columns

(j)> (k), and (4) of Table A2

.

Thus:

HSPF

The seasonal operating cost is evaluated by using equation 4.5. As indicated

also in Table A2 and by assuming a cost of electricity to be $.04/kW, the

seasonal operating cost is approximately $780.

The HSPF and operating cost for the geographic Region V has been calculated in

the above example for a minimum design heating requirement, DHR , . In order

to determine the range of seasonal performance and operating cos^^values for

the unit within the same Region V, the above HSPF and cost calculation sequence

should be repeated using the maximum design heating requirement, DHR . The

quantity DHR is calculated by equation 4.3 and rounded to the nearest value

appearing in"^able 6. The same calculation sequence is then used for determining

the HSPF’s and operating costs for all the standardized design heating requirements appearing in Table 6 which fall between these maximum and minimum design

heating requirements.

ZjCol.

3.413 [ j

j + J

Col. k]

15.219

3.413 [1.7519 + 1.0522]

= 1.59

Continuing with the present example, the maximum standard design heating

requirement for this unit was found from equation (4.3) and Table 6 to equal

110 (kBtu/h). The HSPF and seasonal operating cost for this value of the

42
DHR was calculated, using the procedure first described in generating Table

A2 and is equal to 1.49 and $1830., respectively. The values for the HSPF

for this example heat pump in Region V are presented in Table A3. The calculation procedure is repeated to generate the HSPF's and seasonal operating

costs between the maximum and minimum values. The calculation procedure

should also be repeated for each of the climatic regions specified in Table 5.

Table A1 . Sample Data Required to Calculate the HSPF

for a Single-Speed Heat Pump

0ss(^ 7“F), kBtu/h 48.00

(5i3ef( 35"F), kBtu/h 36.00

QggCl/^F), kBtu/h 30.00

Ess( 47“F), kW 5.023

4.732

Egg(17®F), kW 4.395

Degradation Factor, Cj^ 0.25

T ®F 12.

T “F ^0FF» ' 5.

43
Table

A2

.

Sample

Worksheet

Used

to

Evaluate

the

HSPF

and

the

Seasonal

Cost

of

Operation

for

a

Single-Speed

Compressor

Heat

Pump

(0

(P) (H/n:ia^)

‘pBoi 3 ut:}B3h

eire/((T) (3)

(9)-(P))(3)Um)

XjB^uama-fddng

(H)/(J)

(T)(3)(o)J (m)

‘ :jndui ASjaua

•Data duma 3Ban

C ('X)9

(X)ild

00 C , Ci)x

to XJOH

CM 00 a\ CM ON <f 00 m CO vO CO 00 CO CM CM CM X*-\ ro <r» CM o O cn CO m 00 p^ 00 o UO UO C3N 1 O O CM ITI CM CO ro m CO CO CM p^ o 00 uo • CO m CTi CM 00 vO CO CM ON vO CO CM O o CM CO

• S.-X

r^CTNOO'-ioor^OCNi

oof^'0‘'0’0'oomfn

ooo^t^ooomc^J<-^

r-(l—(CS^rHOOO

CM

CMm

o

o o o o O o o O O o o CM

• s—/

rTMl

II CM vO 00 CO CO 00 o CM NO 00 00 uo ON + O p*^ CO CM uo rH o o ON iJ CM C3N 'd- ON v£» 00 uo o o PV uo ON ON 05 O o o O CM CM CM CM rH o o o o o o o ps. o

CM CM

r-^ '^'^OOOOOO X tcj l-l f-l Li CO (Ua

ON CO 00 00 NO uo o uo NO 00 C3N CM CJN CM uo • ps* 00 00 oo 00 CJN ON CO r-H

r^^i-(cnQOCM-^mr>»i—

t

CNf^f^CT'OCTN00®CT'tM OOi—li-HCOCO'O’lAvOOO

CL|

Cl, w

n

CO

COco

05

CO0) CO

o

00

<J>

c_>00

C3

N

* u

(M^)

‘('x)3

(q/n^g^)

‘(^X)0

(q/n:>aq)

‘ ( ^X) la

‘sanoH uxg

XBUox:iDBaa

r^CM00C0r0O5'^CMCT\mOvOi-tvOCMP^CM00

coc>^cMCMvo^o^N.aoooo'0^oooo^^^^^^c^

cncMr-HOoor^vom'0-cocMr-c0050or'-'Om

mioiiriio-4‘'0‘'a-st>3->0’'a''<fsfcnfncncnco

0000 f0 r>. 0 <nr^000000000 oooofo^oocn^ooooooooo

f—

4

00 00 NO uo CO pH o sf pH 00 uo CM ON NO

uo uo uo si- CO CO CO CO CO CO CM CM CM pH pH pH O NO CO ON rs CM ON uo CM 00 uO pH 00 St pH 't o o

II

'3- o r*^ CO O CO o CO o rs CO O rs CO o Cs uo 0) UO P-4 NO CM 00 CO ON uo o NO CM rs CO ON o NO pH > p^ Li CM 3

NO CJN '3- NO CJN CM 'J- ON CM «o rs o CM uo LI pH t—4 r-H rH CM CM CM CM CO CO CO sr sr St to

Ll NO CM NO NO 00 CM 'J- uo 00 ON 00 O uo CM pH

<ua

o CJN 00 p^ rs 00 O CJN P^ uo sr CO CM i-H o o o It II a

r-H O o o O o ^4 O O o o O O o o o o o (U

c Uo)

i’X ‘aan^aaadmax

aAtaeauasaadag

cMr^cMr^cMr^cMr^cMf-^

vo'Oim«^-<rfOcocMcM<-i

CM r>.

p

‘ ;iaqmnjij ufg •—^cMrO'0lo^or^ooo^o^—icmcO'O’iovo

o0

I—

1

M a > a •H

«k 00 X

> •H ig A CO s

> <u 00 CO M CO a r-l CM Ll

1 1 M 3 U

O o M ,33 o M

«« TJ o M 03 Ll M CO 3 a

rs c» •1 O o 3

»—1 M i-J 0

rH •H 00 3 c

ti c 3 •H o •H o s •H Ll •H OO to 00

(U (U (U

pel 33 o3 44

Design

Heating

Requirement

=

50

(kBtu/h)
Table A3 . HSPF Values

Heat Pump

for the Example Single-Speed Compressor

Capacity at 47“ F = 48(kBtu/h)

ilEGION DHR

(kBtu/h)

HSPF SEASONAL OPEEIATING

COST ($)*

(based on $.04/kWh)

V 110 1.49 1830.

HLH = 2750 100 1.52 1635.

90 1.55 1440.

80 1.58 1225.

70 1.60 1085.

60 1.60 930.

50 1.59 780.

Operating costs in this example have been rounded off to the

nearest $5.

45
Appendix B

Sample Calculations for a Two-Speed Compressor Heat Pump

The following sample calculation illustrates the type of experimental data

required and the use of the tables provided in order to calculate the HSPF

and seasonal cost of operation for a two-speed heat pump installed in

Region IV.

The experimental data required to calculate the HSPF for a fictitious twospeed heat pump is presented in Table Bl. The data and mode of operation

are for illustrative purposes only and are not meant to represent typical or desired performance characteristics. It is assumed that capacity, Q (T.)

and power, E^(T.) at the high speed (k=2) and low speed (k=l) were determined from the previously described test procedures at outdoor temperatures of 17“F (-8.3“C), 35“F (1.7°C), and 47"F (8.3“C). In addition, a steady-state test was conducted at the low (k=l) compressor speed at an outdoor temperature of 62°F (16.7°C). It is further assumed that the unit

in this example is designed to cycle on and off only at the low compressor

speed (k=l), and that a cyclic test was performed at an outdoor temperature

of 47®F with the unit operating at low speed. (In lieu of conducting the

cycling test, a degradation factor of equal to 0.25 could have been

used.) In this example, the unit shall be designed to operate at outdoor

temperature below -23®F so that the compressor cut-out temperature T^p^,,

and compressor cut-in temperature T^^^ are not applicable.

Figure Bl is a graph of the high speed (k=2) and low speed (k=l) capacity

of the two-speed unit versus outdoor temperature. The curves were generated from the example data in Table Bl and from equations 4.34a through

4.34e. Also shown in this figure is a hypothetical building load curve,

which will be discussed later. The purpose of the Figure is to illustrate,

for this particular unit and building load configuration, the various heat

pump operating regions that occur for each temperature bln. Case I operation occurs at relatively high outdoor temperatures where the unit cycles

on and off at low compressor speed (k=l) to meet the small building heating

loads. At lower temperatures, the building load is greater than the lowspeed capacity but less than the high-speed (k=2) capacity. The unit is

designed to run continuously by cycling between the low and high compressor

speeds to satisfy the building load. This mode of operation is designated

by the region labeled Case II.

Case IV operation occurs at still lower outdoor temperatures where the

building load exceeds the high speed (k=2) capacity and supplementary electric resistance heat is required to supply the balance of the heating

requirements

.

Table B2 and the following outline are used to evaluate the HSPF and

seasonal cost of operation for this example two-speed unit.

46
From Table 5 the number of heating load hours, HLH, Is 2250 and the outdoor

design temperature, Tqjj, is 5“F for Region IV. The HSPF shall be calculated

for a minimum design heating requirement. equation 4.2 and the

high-speed capacity test results for Qgg (47), is calculated to be 70

kBtu/h , when rounded to the nearest standardized value appearing in Table 6

.

Column a and b; Temperature Bln Number, j, and Representative Outdoor

Temperature

.

T . —

J

The values are fixed for all calculations.

Column c: Fractional Bin Hours

The fractional number of hours in each temperature bin is determined for

Region IV from Table 5.

Column (d); Building Load

BL(T.) is determined for each representative outdoor temperature from

equation 4.6.

Example ; T^ = 57®F

BL(57) = (.77)(70)

= 7.187 (kBtu/h)

Columns (e), (f), (g), (h); High Speed (k=2) and Low Speed (k=l)

Capacity, (^^(Tj), and Power Input, E^(Tj)

The low speed capacity and power input, Q^“^(TJ, E^'“^(T.), (columns (e) and

(g)) for each representative outdoor temperature T. are determined from

equations 4.34a, b, c, and 4.35a, b, c, and the experimental data presented

in Table Bl

.

Example ; T^ = 57“F

.k=l .k=l

$‘-'(57) . {!^=\47) [Iss -Qss (^^)I (57 - 47)

= 30.00 + (10)

15

= 38.00 (kBtu/h)

47
Example : Tj = 32®F

.k=l .k=l “ QSS

Q (32) = Qgg (17) + (32 - 17)

, [22.00 - 17.00]

= 17.00 +

^ ^(15)

18

= 21.17 (kBtu/h)

Example : Tj = 12“F

.k=l_, .k=l,

Q (12) = C]gg (17) + (12 - 17)

30

= 17.00^

- ^^•QQj

(-5)

30

= 14.83 (kBtu/h)

.k=2 .k=2 The high speed capacity, Q power input E (columns (f) and (h),

respectively) are determined for each respective outdoor'^temperature, T . by

equations 4.34 d, e and 4.35 d, e.

^

Example ; = 57“F

.k=2_, .k=2,

,k=2 .k=2 t^SS “ ^SS

0 (57) =

(5gg (17) + (57 - 17)

30

[65.00 - 42.00],,^,

= 42.00 + ^(40)

30

Example

;

^32 )

= 72.67 (kBtu/h)

Tj = 32“F

•k=2 ^ , .k=2,

.k=2 IQdEF^^^^ “ ^SS

ft (17) + (32 - 17)

18

42.00 ^ L^:^.lil:^(i5)

18

= 48.67 (kBtu/h)

48
Column (i): Applicable Case

A two-speed heat pump will operate in four possible cases, depending on the

unit design and on a comparison of the building load, BL(Tj), relative to

the low and high speed capacities, Q^(Tj), at each representative outdoor

temperature, T.. The four possible modes are described in Section 4.3.

The equation to be used for evaluating the quantities in each of the subsequent columns (j) thorugh (p) will depend on which of the four cases is

applicable for that temperature bin. Figure B1 illustrates the applicable

cases for this particular sample problem.

Example ; Tj = 57®F

BL(57) = 7.187 (kBtu/h)

Q^"^(57) = 38.00 (kBtu/h)

The low speed capacity is greater than the building load, and the unit is

cycling on and off at low speed. The applicable equations for subsequent

calculations are found under Case I.

Example ; Tj = 32°F

BL(32) = 29.645 (kBtu/h)

Q^"^(32) = 21.17 (kBtu/h)

^k=2(32) ^ 48.67 (kBtu/h)

Since BL(32) is less than Q^^^(32) but larger than Q^‘“^(32) and cycles

between high speed and low speed, the equation to be used for subsequent

calculations are found under Case II.

Example ; Tj = 12°F

BL(12) = 47.612 (kBtu/h)

(^•^=2(12) , 38^17 (kBtu/h)

The equation found under Case IV should be used in subsequent calculation

since BL(12) is larger than (^^“^(12) and supplementary resistance heat is

required to meet the balance of the building heating requirements.

49
Columns (j) through (p): Applicable Case I

Example ; Tj = 57®F

6» (57) = 1.0

X^~^(57) = |L(57)

q‘^"^(57)

= = 0.189

38.00

PLFk=l k=l

’d 1 - Cn ^(1 - ^(T.))

= 1 - 0.2 (1 - 0.189) = 0.838

E(57) ^ E^^^(57) X^"^(57) 6»(57) ^ ^ PLF^“^ ^

= (3.028)O189)(l) (.111) = 0.0758 (kW)

• o3o

RH(57) ^ BL(57) fl - 6'(57)]

~N W~

= (111)(7.187)[1 -

IJ ^ 0 (^^^)

.3 • ^ X

Example ; Tj = 42“F

6’(42) = 1.0

X^“^(42) ^ BL(42)

q'^"^(42)

PLF^ ^

E(42)

N

= = 0.795

26.00

1.0 - Cn ^ (1 - X*^ ^(42))

1 - .20 (1-.795) = 0.959

E*^"^(42) X^~^(42) 6 '(42) "j

PLFk=l

50
= (2»881)(0.795)(1.0) (.^oO) = 0.2388 (kW)

.959

RH(42) = BL(42)[1 - 6 '(42)]

N N 3.413

_ (1.00)(20.662)[1 - 1] = n /l,u^

374T3 ^ ^

Coltunns (j) through (p): Applicable Case II

Example ;

6'(32) = 1.0

Tj = 32"F

X^“^(32) ^ Q^~^(32) - BL(32)

Q^"2(32) - Q^"^(32)

= 29.6^ .0.692

48.67 - 21.17

xk=2(32) ^ I _ x^"^(32)

= 1 - 0.692 = 0.308

E(32) ^ .Ak=l k=l

N

' ;k=2. rk=2, (32) X*^^^(32) + E*^"^(32)X'^"^(32)] 6 '(32)

= [(2.803)(0.692) + (6 .163) (0.308) ] (1) ( .126)

= 0.4836 (kW)

RH(32) ^ BL(32)[1 - 6'(32)] ^ ^ N N jTzrn

Columns (k) through (p); Applicable Case IV

Example : Tj = 7“F

6"(7) = 1.0

X^=2(7) =1,0

E(7) ^ X*^=2(7) g..(7) nj

N N

= (4.486)(1)(1)(.013) = .0583 (kW)

RH(Tj)

^ [BL(7) - Q^"^(7) X^"^(7) 6"(7)]

N 3.413 IT

51
= [52.103 - 34.33 (1)(1)] , 0

. 3. 3.413

Q.Uij;

= 0.0677 (kW)

Column (q); Building Heating Requirements for the Temperature Bin

Col. (q) = (Col. d) X (Col. c)

Example : Tj = 57“F

BL(57) p. = (7.187)(.lll)

N

= .7978 (kBtu/h)

The sum of the terms in column (o), in (kW), represents the ratio of the total heat pump electrical energy usage, E(T.), over the heating season to the

total number of hours in all the temperature bins, N. The sum of the values

in column (p), in (kW), represent the ratio of the total amount of supplemental resistance heating, RH(T.), to the total number of temperature bin hours,

N. The ratio of the total building heating requirements to the total number

of temperature bin hours, N, is determined from the sum of the terms in col- umn (q), in (kBtu/h).

The HSPF is then evaluated as indicated in Table B2 or equivalently, by equation 4.13. The HSPF for this example two-speed heat pump in Region IV with

a minimum standard DHR is shown in the Table to be 2.29. The seasonal cost

of operation for a two-speed heat pump is calculated using equation 4.14.

Performing the operations Indicated in the Table and assuming a cost of electricity of $.04 /kWh results in a seasonal operating cost of approximately

$620.

The HSPF and seasonal operating cost of this example two-speed heat pump

should be re-calculated for the same region (Region IV) with the heat pump

installed in a house having the maximum standard design heating requirement,

DHR^^. In calculating DHR^^ ^ , equation 4.3 should be used, rounding off to

the values closest to those appearing in Table 6 . The HSPF values and annual

operating costs between DHR^^^ and should then be calculated to determine the HSPF values and annual operating costs obtained between UliR and

52
Table B1 . Sample Data Required to Evaluate the HSPF

for a Two-Speed Compressor Heat Pump

k=l k=2

Q^(62“F), kBtu/h 42.00 -(2)-

Q^(47“F), kBtu/h 30.00 65.00

Q*^(35'*F), kBtu/h 22.00 50.00

0^(17 “F), kBtu/h 17.00 42.00

E*^(62"F), kW 3.077 -(2)-

£^(47 “F), kW 2.930 7.054

£*^(35 “F), kW 2.865 6.370

£^(17'*F), kW 2.491 5.128

r K

Degradation Factor, ^D .20 -(3)-

-(!)-

Tqff* -(!)-

(1) Unit does not contain a low ambient temperature compressor cut-out

(2) Test not required

(3) Depending on the unit's operation, a value of may be required.

This may be obtained by either a high speed cyclic test or, optionally, using a pre-assimed value of 0.25. In the example illustrated

in Appendix B, no value is required.

53
Table B2. Example Worksheet for Evaluating the HSPF and Seasonal Cost of Operation for a Two-Speed Heat Pump

(a) (b) (c) (d) (e) (f) (g) (h) (1) (j) (k) (1) (m) (n) (o) (P) (q)

3

OX £ 5

1 62 .132 2.695 42.00 76.50 3.077 8.017 I 1 .064 NA .812 NA^ .0320 0 .3557

2 57 .111 7.187 38.00 72.67 3.028 7.696 I 1 .189 NA .838 NA^ .0758 0 . 7970

3 52 .103 11.678 34.00 68.83 2.979 7.375 I 1 .344 NA .869 NA^ .1215 0 1.202b

4 47 .093 16.170 30.00 65.00 2.930 7.054 I 1 .539 NA .908 NA^ .1618 0 1 .5038

5 42 .100 20.662 26.00 53.11 2.881 6.853 1 1 .795 NA .959 NA^ .2388 0 2.06b2

6 37 .109 25.153 22.56 50.89 2.907 6.508 II 1 .909 .091 NA^ NA^ .3526 0 2.7417

7 32 .126 29.645 21.17 48.67 2.803 6.163 II 1 .692 .308 NA^ NA^ .4836 0 3.7353

8 27 .087 34.137 19.78 46.44 2.699 5.818 II 1 .462 .538 NA^ NA^ .3808 0 2.9699

9 22 .055 38.628 18.39 44.22 2.595 5.473 II 1 .217 .783 NA^ NA^ .2667 0 2.1246

10 17 .036 43.120 17.00 42.00 2.491 5.128 IV 1 NA*- 1.0 NA^ NA^ .1846 .0118 1.5523

11 12 .026 47.612 14.83 38.17 2.418 4.807 IV 1 NA^ 1.0 NA^ NA^ .1250 .0719 1.2379

12 7 .013 52.103 12.67 34.33 2.345 4.486 IV 1 NA^ 1.0 NA^ NA^ .0583 .0677 .6773

13 2 .006 56.595 10.50 30.50 2.272 4.165 IV 1 NA^ 1.0 NA*- NA^ .0250 .0459 .3396

14 -3 .002 61.087 8.33 26.67 2.198 3.844 IV 1 NA^ 1.0 NA^ NA^ .0077 .0202 .1222

15 -8 .001 65.578 22.83 _ 3.523 IV 1 NA^ 1.0 NA^ NA^ .0035 .0125 . Ot>36

16 -13 0 70.070 _ 19.00 _ 3.202 IV 1 naI 1.0 NA^ NA^ u 0 U

17 -18 0 74.562 15.17 2.881 IV 1 NA^ 1.0 na'- NA^ 0 0 U

18 -23 0 79.053 _ 11.33 2.560 IV 1 naI 1.0 NA^ NA^ 0 0 U TOTALS 2.5177 .2300 21.4928

Region (I,,11,111, IV,V,VI) IV HSPF “ ZCol. (q) 3.413 ( ECol • (o) + r Col. (P)l Heating Load Hours, (HLH) 2250 (hrs)

Regional Outdoor Design Temperature, (T„„) 5 (°F) _ 21.A928 . 2.29 3.413 [2.5177 + .2300]

' MlnlniuiQ or Maxlmuio

Design Heating Requirement, (DHR) 70 (RBtu/h)

Seasonal

. Operating _ (HLH)(DHR)(C)($/kWh) . (2250) (7Q)( . 77 )

( .04

)

HA means "not appropriate" Cost 3.413 HSPF (3.413) (2 .29) - $620.

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55
NBS-I14A (REV. s-78) r U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 80-2002

4. TITLE AND SUBTITLE

METHOD OF TESTING, RATING AND ESTIMATING THE HEATING SEASONf

PERFORMANCE OF HEAT PUMPS

5. Publication Date L April 1980

7. AUTHOR(S)

Dr. Walter H. Darken, Jr., Dr. George E. Kelly, and —David A.

Didion

8. Performing Organ. Report No. NBSIR 80-2002

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, DC 20234

11. Contract/Grant No.

12. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS rsrreer. City, srate, ZIP)

Department of Energy

Washington, D. C. 20585

13. Type of Report & Period Covered

15. SUPPLEMENTARY NOTES

I I Document describes a computer program; SF-185, FIPS Softwrare Summary, is attached.

16. ABSTRACT (A 200-word or leas factual aunmtary of moat aignificant information, Jf document includes a significant bibliography or

literature aurvey, mention it here,)

Test and rating procedures are presented for electrically-driven residential air-toair heat pumps operating in the heating mode. The procedures are designed to include

the effects of part-load (cyclic) operation, variations in outdoor temperature^ and

frost formation on the heating performance. Using the test procedure results, a calculation procedure is presented for estimating the heating seasonal performance

(HSPF) and cost of operation of residential heat pump units.

17, KEY WORDS (six to twelve entries; alphabetical order; capitalize only the firat letter of the first key word unleaa a proper name;

separated by semicolona)

Central air conditioners; central heating equipment; heat pumps; heating seasonal

performance; rating procedure; residential heating; searonal performance; test method

18. AVAILABILITY [XI Unlimited

I I For Official Distribution. Do Not Release to NTIS

I Order From Sup. of Doc., U.S. Government Printing Office, Washington, DC

20402, SD Stock No. SN003-003-

Order From National Technical Information Service (NTIS), Springfield, VA, 22161

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF

PRINTED PAGES

64

22. Price

$7.00

USCOMM-DC