A111D2 4BbMn

Results and Test

Plan for Differential Temperature

Controllers Used in Solar Energy

Systems

NBS

PUBLICATIONS

J. Greenberg

NATL INST OF STANDARDS & TECH R.I.C.

All 10243641

9

Greenberg, J/Inltlal test results and te QC100 .U56 NO.86-3346 V1986 C.1 NBS-PUB- Initial Test

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Gaithersburg, Maryland 20899

April 1986

-QC

irtment of Energy

Solar Heat Technologies

dings Technology Division

>n, DC 20585

C- 2

100

- U 5 6

86-3346

1986

NBSIR 86-3346

INITIAL TEST RESULTS AND TEST

PLAN FOR DIFFERENTIAL TEMPERATURE

CONTROLLERS USED IN SOLAR ENERGY

SYSTEMS

J. Greenberg

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Gaithersburg, Maryland 20899

April 1986

Prepared for U.S. Department of Energy

Office of Solar Heat Technologies

Solar Buildings Technology Division

Washington, DC 20585

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

NBS RESEARCH INFORMATION CENTER

w -7 O' <?'

PREFACE

SOLAR BUILDINGS RESEARCH AND DEVELOPMENT PROGRAM

In keeping with the national energy policy goal of fostering an adequate

supply of energy at a reasonable cost, the United States Department of

Energy (DOE) supports a variety of programs to promote a balanced and mixed

energy resource system. The mission of the DOE Solar Buildings Research

and Development Program is to support this goal, by providing for the

development of solar technology alternatives for the buildings sector. It

is the goal of the Program to establish a proven technology base to allow

industry to develop solar products and designs for buildings which are economically competitive and can contribute significantly to building

energy supplies nationally. Toward this end, the program sponsors research

activities related to increasing the efficiency, reducing the cost, and

improving the long term durability of passive and active solar systems for

building water and space heating, cooling, and daylighting applications.

These activities are conducted in four major areas: Advanced Passive Solar

Materials Research, Collector Technology Research, Cooling Systems

Research, and Systems Analysis and Applications Research.

The research effort which is described herein falls under Systems Analysis

and Applications Research; an area which encompasses experimental testing,

analysis, and evaluation of solar heating, cooling, and daylighting systems

for residential and non-re sidential buildings. Specifically, this report

documents the initial efforts in developing test procedures for determining

the functional performance of differential controllers used in solar energy

systems in order to mitigate solar control system reliability problems

which have been identified as a major source of failure. It in anticipated

that these procedures will serve as a starting point in the development of

a rational consensus standard for solar controllers.

iii
DISCLAIMER

This report is intended to be an initial effort in developing test

procedures for determining the functional performance of differential

temperature controllers used in solar energy systems. As such, the

controllers tested were used to evaluate the adequacy and completeness of

the test procedures under development and not to judge the performance of

the controllers tested for any specific application. Although the units

tested were not identified by manufacturer, inclusion of a given unit in

this report in no case implies a recommendation or endorsement by the

National Bureau of Standards, and the presentation should not be construed

as a certification that any unit would provide the indicated performance.

Similarly, the omission of a unit does not imply that its capabilities are more or less than those of the included units.

iv
ACKNOWLEDGEMENTS

The author wishes to gratefully acknowledge the contribution of

Steven Facchina for very efficiently and professionally conducting the

tests described herein and to Dianna Mills for her untiring efforts in

preparing and reviewing this document for publication. The author also

wishes to express his appreciation to the following for reviewing the

overall test plan contained in the Appendix: P. Richard Rittelmann, Burt

Hill Kosar Rittlemann Associates; Rob B. Farrington, Solar Energy Research

Institute; T. T. Bradshaw, Vitro Corporation; Andrew J. Parker, Jr.,

Mueller Associates, Incorporated; Pete Jacobs, Novan Energy, Inc.; P. J. Pekrul, Rockwell International; and Edward R. Durlak, Naval Civil

Engineering Laboratory. This program was sponsored by Solar Buildings

Technology Division; Office of Solar Heat Technologies, D.S. Department of

Energy and the efforts of Robert Hassett in providing guidance and support

is also acknowledged.

v

TABLE OF CONTENTS

SECTION TITLE £A£E.

I. INTRODUCTION 1

II. SCOPE OF CONTROLLER TESTS 3

General.. 3

Test Plan Implementation * 4

Test Fixture Used 5 Units Tested 8

III. TEST PROCEDURE, DEVELOPMENT 13

General 13

FUNCTIONAL TESTS - (AMBIENT) 14

TEST 1 - BASELINE FUNCTIONAL TEST (DELTA

T "ON" AND "OFF") 14

Purpose 14

Test Conditions 14

Procedure 16

Results 17

Conclusions........ 23

TEST 2 - RECIRCULATING FREEZE PROTECTION 23

Purpose 23

Test Conditions 23

Procedure 25

Results. 26

Conclusions 32

TEST 3 - CONTROLLER RESPONSE TO SENSOR

TOLERANCE (DELTA T "ON" AND "OFF") 32

Purpose 32

Test Conditions 32

Procedure 36

Results 37

Conclusions 46

TEST 4 - CONTROLLER RESPONSE TO SENSOR

TOLERANCE (RECIRCULATING FREEZE

PROTECTION) 47

Purpose 47

Test Conditions 47

Procedure 48

Results 49

Conclusions 60

vii
TABLE OF CONTENTS (CONTINUED)

SECTION TITLE PAGE

TEST 5 - STORAGE HIGH TEMPERATURE LIMIT 61

Purpose 61

Test Conditions 61

Procedure 63

Results... 64

Conclusions 66

TEST 6 - RECIRCULATING FREEZE PROTECTION

USING AUXILIARY SENSOR 66

Purpose. 66

Test Conditions 66

Procedure 68

Results 69

Conclusions 72

TEST 7 - PUMP "OFF" BELOW 80 °F 72

Purpose 72

Test Conditions 72

Procedure 74

Results 74

Conclusions... 76

SENSITIVITY TO LINE VOLTAGE FLUCTUATION - (AMBIENT) 76

TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE

FLUCTUATION (DELTA T "ON" AND "OFF") 76

Purpose 76

Test Conditions 76

Procedure..... 77

Results 78

Conclusions 85

TEST 9 - CONTROLLER RESPONSE TO LINE VOLTAGE

FLUCTUATION (RECIRCULATING FREEZE PROTECTION).. 85

Purpose 85

Test Conditions 85

Procedure 86

Results 86

Conclusions 92

IV. GENERAL CONCLUSIONS 93

V. REFERENCES 96

APPENDIX A- i

viil
LIST OF TABLES

TABLE TITLE PAGE

1 BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF": UNIT IA. . . 18

2 BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"): UNIT IB... 19

3 BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"): UNIT IC... 20

4 BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"): UNIT Ila.. 21

5 BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"): UNIT lib.. 22

6 RECIRCULATING FREEZE PROTECTION: UNIT IA 27

7 RECIRCULATING FREEZE PROTECTION: UNIT IB 28

8 RECIRCULATING FREEZE PROTECTION: UNIT IC 29

9 RECIRCULATING FREEZE PROTECTION: UNIT Ila 30

10 RECIRCULATING FREEZE PROTECTION: UNIT lib 31

11 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE +0 .5 °F/COLLECTOR -0.5°F:

UNITS IA, IB, AND IC 38

12 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE -0 .5 °F/COLLECTOR +0.5°F:

UNITS IA, IB, AND IC 3 9

13 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE +1 .0 °F/COLLECTOR -1.0 °F:

UNITS IA, IB, AND IC 40

14 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE -1 .0 °F/COLLECTOR +1.0°F:

UNITS IA, IB, AND IC 41

15 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE +0 .5 °F/ COLLECTOR -0.5 °F:

UNIT Ila, lib 42

16 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE -0 . 5 °F/COLLECTOR +0.5 °F:

UNIT Ila, lib 43

17 CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE +1 .0 °F/COLLECTOR -1.0°F:

UNIT Ila, lib 44

ix
18

19

20

21

22

23

24

25

26

27

28

29

30

45

50

51

52

53

54

55

56

57

58

59

65

70

LIST OF TABLES (CONTINUED)

TITLE

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF"); STORAGE -1 .0 °F/ COLLECTOR +1.0°F:

UNIT Ha, lib

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

+0.5 °F/ COLLECTOR -0.5 °F: UNITS IA, IB, AND IC....

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

-0.5 °F/ COLLECTOR +0.5°F: UNITS IA, IB, AND IC....

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

+1.0 °F/ COLLECTOR -1.0 °F: UNITS IA, IB, AND IC....

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

-1.0 °F/ COLLECTOR +1.0°F: UNITS IA, IB, AND IC....

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

+0 . 5 °F/ COLLECTOR -0 .5 °F: UNIT Ha, lib

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

-0.5 °F/ COLLECTOR +0.5°F: UNIT Ha, lib

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

+1 . 0 °F/ COLLECTOR -1.0°F: UNIT Ha, lib

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); STORAGE

-1 . 0 °F / COLLECTOR +1.0°F: UNIT Ha, lib

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); CHANGES

IN VALUE FROM BASELINE: UNIT IA

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION); CHANGES

IN VALUE FROM BASELINE: UNIT Ha

CONTROLLER RESPONSE TO STORAGE HIGH TEMPERATURE

LIMIT: UNITS IA, IB AND IC; Ha, lib

CONTROLLER RESPONSE USING AUXILIARY SENSOR INPUT

(DELTA T "ON" AND "OFF"): UNITS IA, IB, AND IC...

x
TABLE

31

32

33

34

35

36

37

38

39

40

LIST OF TABLES (CONTINUED)

TITLE PASS.

CONTROLLER RESPONSE USING AUXILIARY SENSOR INPUT

(RECIRCULATING FREEZE PROTECTION): UNITS LA, IB,

AND IC 71

PUMP "OFF" BELOW 80 °F: UNIT Ha, lib 75

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF"); 90 VAC: UNITS IA,

IB, AND IC 80

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF"); 130 VAC: UNITS IA,

IB, AND IC 81

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF"); 90 VAC: UNIT Ha,

lib 82

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF"); 130 VAC: UNIT Ha,

lib 83

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION); 90 VAC:

UNITS IA, IB, AND IC 88

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION); 130 VAC:

UNITS IA, IB, AND IC 89

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION); 90 VAC:

UNIT Ha, lib 90

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION); 130 VAC:

UNIT Ha, lib 91

xi
LIST OF FIGURES

FIGURE TITLE EASE.

1 CONTROLLER TEST FIXTURE 6

2 TEMPERATURE/ RESISTANCE TABLE 9

3 SUMMARY OF CONTROLLER FEATURES FOR UNITS TESTED 12

4 MODIFIED TEMPERATURE/ RES I STANCE TABLE 34

5 OPERATING CHARACTERISTICS AT VARYING VOLTAGES

(DELTA T "ON” AND "OFF": UNIT Ha 84

xii
I INTRODUCTION

From the inception of the Department of Energy (DOE) active solar heating

and cooling program, control system reliability problems have been

identified as a major source of failure. Although the sensor elements of

the control systems have contributed to a number of these failures and

operational problems [1], recent reports by the Solar Energy Research

Institute (SERI) [2, 3] include extensive literature reviews that indicate

the controllers themselves are a source of failure. Another SERI report

[4] covering the results of a detailed survey of 122 operational

residential solar water heater systems concludes: "Differential Controllers

were responsible for the largest number of failures that resulted in repair

cost in excess of $50 to the home owner." In addition, the results of

tests conducted on controllers by SERI [3] concludes: "These tests reveal

current problems with ... controller accuracy, heat and humidity effects,

long-term electronics, failure to meet specifications, poor instructions,

and incorrect color-coding of wires."

In a related effort under the DOE Systems Effectiveness Research Program,

two meetings were held at the National Bureau of Standards (NBS) in August

1983 to develop research priorities for improving the effectiveness of

active solar hot water and space conditioning systems. The meetings were attended by solar industry representatives (manufacturers, contractors,

architects and engineers) as well as government representatives. The

recommended research priorities developed by this group was documented in a

recently published NBS report [5] and cited control systems as the highest

ranked research area that is appropriate for Federal Government support.

Included in the solar controls research area is a recommended objective for

1
a DOE-sponsored controls research program including the development of

standard test methods and evaluation procedures for assessing the

performance of controller hardware and controller interfaces.

Specifically, the report states: "These [SERI] tests are important to the

control ler manufacturers. However, the tests should be expanded to include

more controller types and additional environmental conditions. A review

committee, comprised of manufacturers and DOE/SERI/NBS personnel, should be

formed to provide advice regarding the tests to be performed."

In view of the above, this report documents the initial efforts in

developing test procedures for determining the functional performance of

differential temperature controllers used in solar energy systems.

Included in this report is an overall test plan outline that has been sent

to individuals at Government laboratories, controller manufacturers, and

others having interests in differential temperature controllers. The

overall test plan incorporating comments received is included in the

Appendix. In addition, the body of this report contains the results of an

initial effort to develop test procedures to evaluate the functional

characteristics and controller response to line voltage fluctuation at

normal room ambient conditions for non-ad justab le controllers. For each

test, the purpose is stated and the test condition, procedures, results,

and conclusions detailed.

It is anticipated that these test procedures will serve as a starting point

in the development of a rational consensus standard for solar controllers.

2
II. SCOPE OF CONTROLLER TESTS

Gaaejal

The overall planning for the test procedure development for differential

temperature controllers envisioned the testing of a broad range of

controllers procured from a number of sources. One end of this broad

spectrum included the most basic controllers of the non-display, nonad justable type while the other end included those controllers equipped

with a host of optional modes, displays, settings, etc. Because of funding

limitations, the scope for this initial effort was confined to testing

those units that could provide a solid, though limited test base, that

later could be expanded. Consequently, the units selected were the basic

non-ad jus tab le, non-display type controllers although these units featured

a limited number of adjustable options and other functions which were also

evaluated

Four units were selected for testing; three identical controllers procured

from a single manufacturer and a single, similar type unit procured from a

second source. The three units were chosen in order to assess whether the

test procedures could characterize the performance differences between

identical units from a single manufacturer with the single, similar unit

chosen to assess the difference in performance between controllers procured

from separate sources. Initially, tests were intended to be limited to

only characterizing the controller's functional response under the nominal

controller operating conditions of 70 °F and the nominal power input of 115

VAC at 60 Hertz. Because the test fixture was designed with a feature that

allowed the controller's input voltage to be easily adjusted, additional

3
tests were conducted to determine the controller's response to line voltage

fluctuation.

Test Plan Implementation

The testing of differential temperature controllers described in this

report is an initial step in implementing the overall test plan included in

the Appendix. Although the overall test plan provides a comprehensive

array of proposed tests covering all aspects of controller performance

under a variety of environmental conditions, the tests described herein

correspond specifically to the following tests outlined in the overall

plan:

FUNCTIONAL TESTS - (AMBIENT)

Non-ad jus table Unit

delta T "ON"

delta T "OFF"

Storage High Temperature Limit

Recirculating Freeze Protection

Other Features

Adjustable Unit

Storage High Temperature Limit

Other Features

SENSITIVITY TO LINE VOLTAGE FLUCTUATION - (AMBIENT)

Non-ad justab le Unit

delta T "ON"

delta T "OFF"

Recirculating Freeze Protection

4
The three identical units procured from a single manufacturer included the

optional feature for providing an auxiliary input for RECIRCULATING FREEZE

PROTECTION. Separate tests were conducted to determine the controller's

response under these conditions as an implicit requirement of the overall

test plan. In addition, the single unit procured from a second source was

provided with a PUMP "OFF1

' BELOW 80 °F option. Although this is an uncommon

controller option and was not identified specifically in the overall test

plan, this feature was also tested and the results included in this report.

Additional tests were conducted to characterize the controller's response

to the manufacturing tolerances associated with the sensor. These include

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND "OFF") and

CONTROL RESPONSE TO SENSOR TOLERANCE (RECIRCULATING FREEZE PROTECTION).

These tests are intended to reconcile the behavior of actual sensors

installed in operating solar systems with the simulated sensors used to

conduct the controller tests and to form a strong basis for interfacing

sensor performance with controller performance.

Test Fixture Used

To facilitate controller testing, a test fixture was constructed as shown

schematically in Figure 1. Power was obtained from an ordinary laboratory

branch circuit electrical receptacle and fed through a variac and a power

switch to the controller being tested. For testing under ambient voltage

conditions, the variac was held at a constant 115 VAC at 60 Hertz with the

parallel voltmeter confirming the input voltage. For tests conducted to

determine the controller's SENSITIVITY TO LINE VOLTAGE FLUCTUATION, the

variac was adjusted to provide the power input at the desired higher or

5
CONTROLLER

TEST

FIXTURE

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3: 3 2^

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6

DECADE

RESISTANCE

BOX
lower voltage. For example, the variac was set and held at 90 VAC and

later at 130 VAC for the voltage tests described later in this report. The

controller's pump output was simulated by an electric light bulb which gave

a very positive indication of controller relay activation. A thermometer

indicated controller ambient temperature.

The differential temperature controller to be tested was wired as shown in

Figure 1 following the manufacturer's instructions. A large amount of

slack was left in the power wiring between the controller and both the

power switch and electric bulb to facilitate the installation and removal

of the controllers. The excess slack was placed in the back of the test

fixture by threading it through holes drilled in the vertical board of the

test fixture (not shown in Fig. 1). The sensor leads were connected to the

controller as recommended by the manufacturer and fixed to a terminal strip

on the test fixture. Generally, only four terminals are used; two for the

storage sensor and two for the collector sensor. However, provision was

made on the terminal strip to accommodate additional sensor leads since

some controllers have operating options which require additional sensor

inputs.

The controller temperature inputs were simulated using accurately

calibrated decade resistance boxes. These resistances correspond to

thermistor operating temperatures. A typical temperature/res is tance table

is shown in Figure 2. Although these decade boxes were used to simulate

thermistor sensors, the most common type of sensor currently in use in

solar applications, the test fixture can be used for different sensor types

as well. For example, a decade resistance box can also be used to simulate

7
a resistance temperature detector (RTD) sensor and perhaps an accurate

voltage source to simulate a thermocouple sensor.

The use of simulated temperature inputs to the controller greatly expedited

the tests. Although the tests could conceptually be conducted using actual

thermistors, the effort involved would be highly impractical considering

the large number of test points involved. For example, if implemented for

a delta T "ON" test, the actual storage thermistor would have to be placed

in a temperature bath and stabilized to some fixed temperature. The

collector sensor would be located in another temperature bath and the

temperature of this bath slowly raised until the controller "ON" circuit is

activated, and the bath actuating temperature accurately recorded. Because

of measurement uncertainties, this very time consuming procedure may have

to be repeated several times to get a representative reading just for one delta T "ON" point. The simulated sensor procedure for a delta T "ON"

test, on the other hand, requires a known resistance to be set on the

storage simulator decade resistance box and the knobs on the collector

simulator decade resistance box turned until the delta T "ON" function is

activated. The resistance is read and converted into a temperature. The

controller triggering point using this method has proven to be very

repeatable with each individual delta T "ON" measurement being accomplished

in less than a minute.

Units Tested

For the initial tests, the differential temperature controllers selected

were generally non-ad justab le units with no display function. Some of th.

units, however, had certain adjustable features and these were also

8
Figure 2

TEMPERATURE/RESISTANCE TABLE

10,000 ohm THERMISTOR AT 77 °F

°F Ohms °F Ohms °F Ohms F Ohms

32.0 32660 78.0 9760 123.0 3526 168.0 1453

33.0 31748 79.0 9526 124.0 3453 169.0 1427

34.0 30864 80.0 9299 125.0 3381 170.0 1401

35.0 30008 81.0 9078 126.0 3311 171.0 1376

36.0 29178 82.0 8862 127.0 3243 172.0 1351

37.0 28375 83.0 8653 128.0 3176 173.0 1326

38.0 27596 84.0 8449 129.0 3111 174.0 1303

39.0 26840 85.0 8250 130.0 3048 175.0 1279

40.0 26109 86.0 8057 131.0 2986 176.0 1256

41.0 25400 87.0 7869 132.0 2925 177.0 1234

42.0 24711 88.0 7685 133.0 2866 178.0 1212

43.0 24045 89.0 7507 134.0 2808 179.0 1191

44.0 23399 90.0 7333 135.0 2751 180.0 1170

45.0 22771 91.0 7164 136.0 2696 181.0 1149

46.0 22162 92.0 6999 137.0 2642 182.0 1129

47.0 21572 93.0 6839 138.0 2589 183.0 1109

48.0 21000 94.0 6683 139.0 2538 184.0 1090

49.0 20444 95.0 6531 140.0 2488 185.0 1071

50.0 19906 96.0 6382 141.0 2438 186.0 1052

51.0 193 82 97.0 6238 142.0 2390 187.0 1034

52.0 18875 98.0 6097 143.0 2343 188.0 1016

53.0 18382 99.0 5960 144.0 2297 189.0 999

54.0 17904 100.0 5827 145.0 2253 190.0 982

55.0 17440 101.0 5696 146.0 2209 191.0 965

56.0 16990 102.0 5570 147.0 2166 192.0 948

57.0 16552 103.0 5446 148.0 2124 193.0 932

58.0 16127 104.0 5325 149.0 2083 194.0 916

59.0 15715 105.0 5208 150.0 2043 195.0 901

60.0 15314 106.0 5093 151.0 2003 196.0 886

61.0 14925 107.0 4981 152.0 1965 197.0 871

62.0 14547 108.0 4873 153.0 1928 198.0 856

63.0 14180 109.0 4767 154.0 1891 199.0 842

64.0 13823 110.0 4663 155.0 1855 200.0 828

65.0 13476 111.0 4562 156.0 1820 201.0 814

66.0 13139 112.0 4463 157.0 1786 202.0 800

67.0 12812 113.0 4367 158.0 1752 203.0 787

68.0 12494 114.0 4274 159.0 1719 204.0 774

69.0 12185 115.0 4182 160.0 1687 205.0 761

70.0 11884 116.0 4093 161.0 1656 206.0 749

71.0 11592 117.0 4006 162.0 1625 207.0 737

72.0 11308 118.0 3921 163.0 1595 208.0 725

73.0 11031 119.0 3838 164.0 1565 209.0 713

74.0 10763 120.0 3757 165.0 1536 210.0 701

75.0 10502 121.0 3678 166.0 1508 211.0 690

76.0 10248 122.0 3601 167.0 1481 212.0 697

77.0 10000

9
evaluated as part of the test procedures. In total, four units were tested

for functional evaluation and sensitivity to line voltage fluctuation.

Three of the four units were identical models procured from a single

manufacturer and the fourth controller, of a similar type, was procured

from a second source.

The three identical units are designated units IA, IB, and IC throughout

this report. They each have a fixed delta T "ON" of 20 °F and a delta T

"OFF" of 5 °F (designated hereinafter as 20/5). As an option, the

controller can be wired for recirculating freeze protection by either using

the collector sensor as the freeze indicating element, or through the use

of a separate freeze sensor. In the recirculating freeze protection mode,

the indicating element would cause the circulating pump to be activated

when the temperature falls to approximately 40 °F and deactivated when the

temperature rises to approximately 44°F. In addition, these differential

temperature controllers have infinitely adjustable storage high temperature

limits that can be set by rotating a trimpot knob on the circuit board to

the desired setting between 105°F and 212°F. In operation, the circulating

pump is deactivated when the storage tank temperature exceeds the high

temperature limit setting. These controllers have a single relay output

and operate at a nominal line voltage of 115 VAC at 60 Hertz. Also, no

temperature display is provided.

The single controller procured from a second manufacturer is similar to the

three identical units described above. The key distinguishing feature

of this unit permits the user to change the controller differential

temperature range by pressing a rocker switch located internal ly on th.

10
printed circuit board. With the switch in one position, the delta T "ON"

is fixed at 18°F and the delta T "OFF" fixed at 5 °F (designated hereinafter

as 18/5). With the switch in the other position, the delta T "ON*' is fixed

at 9°F and the delta T "OFF" fixed at 4°F (similarly designated hereafter

as 9/4). Although a single unit, test sequences were conducted separately

for the 18/5 mode and the 9/4 mode. These tests are designated throughout

this report as Ha and lib, respectively. This unit can be operated in the

recirculating freeze protection mode only by using the collector sensor as

the freeze indicator. (It should be noted that for both types of units,

additional thermistors or "snap" switches are recommended for installation

in the collector circuit for added freeze protection.) Other features of

this unit allow for a printed circuit board switch setting of the storage

high temperature limit to either OFF, 180 °F, or 160°F and an option that

provides PUMP "OFF" BELOW 80 °F. When this option is selected by moving an

internal switch, the pump will not turn on when the collector sensor

temperature is below 80 °F. This feature prevents water circulation at

night after a large amount of hot water has been consumed or when a reverse

thermosyphon effect would normally cause the pump to turn on. Enabling the

recirculating freeze protection mode, however, overrides this option. This

controller also has a single relay output, operates at a nominal line

voltage of 115 VAC at 60 Hertz, and has no temperature display.

The features describe above for the units tested are tabulated in

Figure 3.

1
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OF

CONTROLLER

FEATURES

FOR

UNITS

TESTED

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12

(5)

Freeze

Protection

Enabling

Switch

Overrides

this

Function
Ill TEST PROCEDURE DEVELOPMENT

General

This section documents the specific tests conducted on the differential

temperature controllers described in Section II. The following is included

for each test: (1) the purpose of the test; (2) the test conditions and

other detailed information concerning the tests or the units tested; (3)

the test procedures used; (4) the test results; and (5) the conclusions

reached concerning the adequacy of the procedure used. Shown below is a

complete listing of all tests conducted.

TEST NAME UNIT

NO.

FUNCTIONAL TESTS - (AMBIENT)

1 BASELINE FUNCTIONAL TEST (DELTA T "ON"

AND "OFF")

IA; IB; IC; Ila.IIb

2 RECIRCULATING FREEZE PROTECTION IA; IB; IC; Ila, lib

3 CONTROLLER RESPONSE TO SENSOR TOLERANCE

(DELTA T "ON" AND "OFF")

IA; IB; IC; Ila , lib

4 CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION)

IA; IB; IC; Ila , lib

5 STORAGE HIGH TEMPERATURE LIMIT IA; IB; IC; Ila.IIb

6 RECIRCULATING FREEZE PROTECTION USING

AUXILIARY SENSOR

IA; IB; IC

7 PUMP "OFF" BELOW 80 °F Ha , lib

SENSITIVITY TO LINE VOLTAGE FLUCTUATION - (AMBIENT)

8 CONTROLLER RESPONSE TO LINE VOLTAGE

FLUCTUATION (DELTA T "ON" AND "OFF")

IA; IB; IC; Ila , lib

9 CONTROLLER RESPONSE TO LINE VOLTAGE IA; IB; IC; Ila , lib

FLUCTUATION (RECIRCULATING FREEZE

PROTECTION)

Although the tests were performed using simulated thermistor input to the

controller and the test procedures written for simulated thermistor input,

13
with little modification the procedures would apply to other types of

sensor inputs* Although the test procedures indicated result from the

testing of units that are largely of the non-adjustab le, non-display type,

with some minor modification the test procedures are probably valid for

units with adjustable options and display features as well. This should be

confirmed, however, through actual testing of such units. In addition, the

data collected during these tests will form the basis for evaluating the

controller when data from tests run at extreme ambient conditions are

compared and analyzed.

FUNCTIONAL TESTS-C AMBIENT)

THE FOLLOWING TESTS WERE CONDUCTED TO EVALUATE THE CONTROLLER'S FUNCTIONAL

CHARACTERISTICS. THE TESTS WERE CONDUCTED AT AMBIENT CONDITIONS OF

APPROXIMATELY 70 °F WITH POWER SUPPLIED AT 115 VAC AT 60 HERTZ.

TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF")

Purpose

This test is intended to serve as a baseline to characterize the overall

delta T "ON" and "OFF" response of the differential temperature controller

over a broad range of input signals and as a reference for analyzing other

test results.

Test Conditions

This test is performed using the nominal temperature/resis tance table for

the sensors provided or recommended for use with the controller. (This

table is shown in Figure 2.) Delta T "ON" and "OFF" tests are conducted at

5 °F intervals over the expected operating range using resistance decade

14
boxes to simulate operating temperatures* The tests are performed at

ambient conditions and with power being supplied at nominal line voltage.

Other functional features such as STORAGE HIGH TEMPERATURE LIMIT, PUMP

"OFF" BELOW 80 °F, etc. are generally switched off, not connected, or

otherwise made inoperable. (Tests of these features are described in

subsequent sections of this report.)

Specifically, for the three identical units tested (IA, IB, and IC) , the

adjustable STORAGE HIGH TEMPERATURE LIMIT was set to "OFF" and the single

fixed delta T "ON" and "OFF" (20/5) tested as described below. For the

other unit tested, both the adjustable STORAGE HIGH TEMPERATURE LIMIT and

the PUMP "OFF" BELOW 80 °F features were switched to "OFF". Because the

unit contains a switch selectable option for operating at 18/5 or 9/4,

separate delta T "ON" and "OFF" tests were run at each setting (Tests Ila

and lib). Tests on all units were conducted at a room ambient of

approximately 70 °F* and an input voltage of 115 VAC at 60 Hertz.

In addition, baseline tests for all units were conducted with the storage

simulator fixed and the collector simulator varied until the tested

switching function was activated or deactivated. The tests were conducted

with the simulated storage sensor set at 60 °F and raised in increments of

5 °F until the upper limit of 210 °F was reached. These values were selected

since water inlet temperatures generally do not range much lower than 60 °F

and storage temperatures are rarely allowed to reach boiling temperatures.

All temperatures in this report are expressed in degrees Fahrenheit as

it is common practice in the solar controller industry to generally

use English units for temperature/resis tance tables, delta T values,

and physical controller markings and settings.
The test results were found to be consistently repeatable (±2 ohms) and,

consequently, each delta T "ON*' and "OFF" test was conducted only once.

Procedure

1. All tests are conducted using the nominal temperature/ res is tance

table provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Set the storage and collector sensor simulated temperatures

(resistance) to correspond to the lowest storage temperature to be

tested

3. Increase the collector sensor simulated temperature (by decreasing the

resistance) until the pump output is activated and record the

resistance corresponding to the delta T "ON" temperature.

4. Decrease the collector sensor simulated temperature (by increasing the

resistance) until the pump output is deactivated and record the

resistance corresponding to the delta T "OFF" temperature.

5. Repeat step 2 after increasing the simulated storage temperature by

5°F (by decreasing the resistance).

6. Repeat steps 3 and 4.

7. Continue this procedure until the storage and collector simulated

temperatures (resistance) correspond to the highest temperature to be

tested

8. Convert the recorded resistances to operating temperatures using the

nominal temperature/resis tanc e table appropriate for the simulated

sensor.

16
9. Controllers designed with the option to select more than a single

fixed delta T "ON" and "OFF" shall be tested separately at each

discrete switch setting.

Results

The delta T "ON" and "OFF" response for the three identical units tested

are shown for Units IA, IB, and IC in Tables 1, 2, and 3, respectively.

The manufacturer's literature for these controllers specify a controller

delta T "ON" accuracy of 20°±2.5°F. As can be seen, the tests indicated

all controllers operated within the specification over an operating range

of 60° through 210°F with the exception of controller IB which was

activated at a delta T "ON" of 17.2°F when the storage temperature was

fixed at 60 °F. All three of the controllers (IA, IB, and IC) were seen to

operate out of manufacturer's delta T "OFF" specification (5° + 2.5 °F) at

the high storage temperature settings.

The delta T "ON" and "OFF" response for the second unit tested is shown in

Table 4 and 5. Table 4 represents the response when the unit is set in the

18/5 mode (Ha) and Table 5 for the 9/4 sett ing (lib). Since no accuracy

range was specified for this unit, for purposes of this report the accuracy

specified for the first three units tested (IA, IB, and IC) was used.

Under this assumed accuracy condition, it is noted that the unit procured

from the second manufacturer operated within the tolerance indicated for

both settings (Ha and lib) in the delta T "ON" and "OFF" mode over the

entire range tested.
TABLE 1

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF")

UNIT IA

Storage

Delta T ON Delta T CFF

Temp Outside In Outside Outside In Outside

Setting Collector Spec. Spec.* Spec. Collector Spec. Spec .* Spec

Temp. (Low)

20°F

(High) Temp. (Low)

5*F

(High)

•F °F <17.5°F ±2.5°F >22.5°F °F <2.5*F ±2.5*F >7.5°F

60 77.8 17.8 65.8 5.8

65 83.0 18.0 70.9 5.9

70 88.2 18.2 75.9 5.9

75 93.4 18.4 80.9 5.9

80 98.8 18.8 85.9 5.9

85 104.0 19.0 90.8 5.8

90 109.3 19.3 95.7 5.7

95 114.5 19.5 101.0 6.0

100 119.8 19.8 106.0 6.0

105 125.0 20.0 111.0 6.0

110 130.3 20.3 116.0 6.0

115 135.5 20.5 121.0 6.0

120 140.7 20.7 126.0 6.0

125 145.9 20.9 130.9 5.9

130 151.0 21.0 135.8 5.8

135 156.2 21.2 140.8 5.8

140 161.2 21.2 145.7 5.7

145 166.2 21.2 150.5 5.5

150 171.2 21.2 155.3 5.3

155 176.6 21.6 160.2 5.2

160 181.6 21.6 164.9 4.9

165 186.7 21.6 169.5 4.5

170 191.6 21.6 174.2 4.2

175 196.6 21.6 179.1 4.1

180 201.5 21.5 183.6 3.6

185 206.5 21.5 188.3 3.3

190 211.5 21.5 192.9 2.9

195 216.4 21.4 197.5 2.5

200 221.2 21.2 202.0 2.0

205 226.1 21.1 206.6 1.6

210 230.8 20.8 211.0 1.0

Accuracy specified by manufacturer - Delta T ON 20*F + 2.5°F

Delta T CFF 5°F 2.5*F

18
TABLE 2

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF")

UNIT IB

Storage

Temp

Delta T ON Delta T OFF

Outside In Outside Outside In Outside

Setting Collector

Temp*

Spec • (Low)Spec.* Spec.

(High)

Collector

Temp.

Spec.

(Low)

Spec.* Spec

(High)

20°F 5 °F

°F °F <17.5°F ±2.5°F >22.5°F ®F <2.5°F ±2.5°F >7.5°F

60 77.2 17.2 65.4 5.4

65 82.4 17.5 70.4 5.4

70 87.7 17.7 75.5 5.5

75 92.8 17.8 80.5 5.5

80 98.2 18.2 85.4 5.4

85 103.4 18.4 90.4 5.4

90 108.6 18.6 95.3 5.3

95 113.9 18.9 100.6 5.6

100 119.1 19.1 105.5 5.5

105 124.4 19.4 110.5 5.5

110 129.6 19.6 115.5 5.5

115 134.8 19.8 120.5 5.5

120 140.0 20.0 125.5 5.5

125 145.2 20.2 130.4 5.4

130 150.3 20.3 135.3 5.3-

135 155.5 20.5 140.3 5.3

140 160.5 20.5 145.2 5.2

145 165.5 20.5 150.0 5.0

150 170.5 20.5 154.8 4.8

155 175.5 20.5 159.7 4.7

160 180.9 20.9 164.4 4.4

165 185.9 20.9 169.0 4.0

170 190.8 20.8 173.6 3.6

175 195.8 20.8 178.6 3.6

180 200.7 20.7 183.1 3.1

185 205.7 20.7 187.8 2.7

190 210.7 20.7 192.4 2.4

195 215.6 20.6 196.9 1.9

200 220.4 20.4 201.4 1.4

205 225.1 20.1 206.0 1.0

210 230.0 20.0 210.4 0.4

Accuracy specified by manufacturer - Delta T ON 20°F + 2.5°F

Delta T CFF 5°F ± 2.5°F

19
TABLE 3

BASELINE FUNCTIONAL TEST (DELTA T "ON” AND "CFF")

UNIT IC

Storage

Delta T ON Delta T CFF

Temp Outside In Outside Outside In Outside

Setting Collector Spec . Spec.* Spec. Collector Spec. Spec .* Spec

Temp. (Low) (High) Temp. (Low) (High)

20 °F 5*F

°F °F <17.5*F ±2.5°F >22.5°F °F <2.5°F ±2.5*F >7.5 °F

60 77.8 17.8 65.9 5.9

65 83.1 18.1 70.9 5.9

70 88.3 18.3 76.0 6.0

75 93.5 18.5 81.0 6.0

80 98.9 18.9 86.0 6.0

85 104.1 19.1 90.9 5.9

90 109.3 19.3 95.8 5.8

95 114.6- 19.6 101.1 6.1

100 119.8 19.8 106.1 6.1

105 125.1 20.1 111.1 6.1

110 130.3 20.3 116.1 6.1

115 135.6 20.6 121.1 6.1

120 140.8 20.8 126.1 6.1

125 146.0 21.0 131.0 6.0

130 151.1 21.1 136.0 6.0

135 156.3 21.3 140.9 5.9

140 161.3 21.3 145.8 5.8

145 166.3 21.3 150.6 5.6

150 171.3 21.3 155.4 5.4

155 176.7 21.7 160.3 5.3

160 181.7 21.7 165.0 5.0

165 186.7 21.7 169.7 4.7

170 191.7 21.7 174.3 4.3

175 196.7 21.7 179.2 4.2

180 201.7 21.7 183.8 3.8

185 206.7 21.7 188.4 3.4

190 211.7 21.7 193.1 3.1

195 216.6 21.6 197.6 2.6

200 221.4 21.4 202.2 2.2

205 226.2 21.2 206.7 1.7

210 230.9 20.9 211.1 1.1

Accuracy specified by manufacturer - Delta T ON 20*F 2.5*F

Delta T CFF 5°F ± 2.5*F

20
TABLE 4

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF")

UNIT I la

Delta T ON Delta T OFF

Temp Outside In Outside Outside In Outside

Setting Collector Spec. Spec .* Spec. Collector Spec. Spec.* Spec

Temp. (Low) (High) Temp. (Low) (High)

18°F 5°F

•f °F <15.5°F ±2.5°F >20.5°F °F <2.5°F ±2.5°F >7.5°F

60 75.8 15.8 65.9 5.9

65 80.1 15.9 70.9 5.9

70 86.0 16.0 75.9 5.9

75 91.1 16.1 80.9 5.9

80 96.4 16.4 85.9 5.9

85 101.5 16.5 90.8 5.8

90 106.5 16.5 95.7 5.7

95 111.6 16.6 100.9 5.9

100 116.8 16.8 105.9 5.9

105 121.9 16.9 110.8 5.8

110 127.0 17.0 115.8 5.8

115 132.2 17.2 120.9 5.9

120 137.4 17.4 126.1 6.1

125 142.6 17.6 131.2 6.2

130 147.8 17.8 136.2 6.2

135 153.0 18.0 141.3 6.3

140 158.1 18.1 146.4 6.4

145 163.1 18.1 151.4 6.4

150 168.2 18.2 156.5 6.5

155 173.2 18.2 161.5 6.5

160 178.6 18.6 166.5 6.5

165 183.6 18.6 171.5 6.5

170 188.7 18.7 176.7 6.7

175 193.8 18.8 181.7 6.7

180 198.8 18.8 186.7 6.7

185 203.9 18.9 191.7 6.7

190 209.0 19.0 196.9 6.9

- 195 214.0 19.0 202.0 7.0

200 219.0 19.0 207.1 7.1

205 224.1 19.1 212.2 7.2

210 229.0 19.0 217.3 7.3

* Delta T ON 18°F

Delta T OFF 5°F

Accuracy not specified by manufacturer

21
TABLE 5

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "CFF")

UNIT lib

Storage

Delta T ON Delta T CFF

Temp. Outside In Outside Outside In Outside

Setting Collector Spec • Spec.* Spec. Collector Spec. Spec.* Spec • Temp. (Low) (High) Temp. (Low) (High)

9°F 4*F

*F °F <6.5*F ±2.5*F >11.5*F •f <1.5°F ±2.5*F >6.5°F

60 68.5 8.5 65.0 5.0

65 73.5 8.5 70.0 5.0

70 78.5 8.5 75.0 5.0

75 83.5 - 8.5 80.0 5.0

80 88.5

* 8.5 85.0 5.0

85 93.4 8.4 89.9 4.9

90 98.6 8.6 94.8 4.8

95 103.6 8.6 100.0 5.0

100 108.5 8.5 104.9 4.9

105 113.5 8.5 109.9 4.9

110 118.6 8.6 114.9 4.9

115 123.7 8.7 120.0 5.0

120 128.7 8.7 125.0 5.0

125 133.8 8.8 130.1 5.1

130 138.9 8.9 135.2 5.2

135 143.9 8.9 140.3 5.3

140 149.0 9.0 145.4 5.4

145 153.9 8.9 150.4 5.4

150 158.9 8.9 155.4 5.4

155 163.9 8.9 160.4 5.4

160 168.8 8.8 165.4 5.4

165 173.6 8.6 170.3 5.3

170 178.9 8.9 175.3 5.3

175 183.7 8.7 180.6 5.6

180 188.6 8.6 185.6 5.6

185 193.5 8.5 190.7 5.7

190 198.5 8.5 195.7 5.7

195 203.3 8.3 200.8 5.8

200 208.2 8.2 205.8 5.8

205 213.2 8.2 211.0 6.0

210 218.0 8.0 216.1 6.1

* Delta T ON 9°F

Delta T OFF 4°F

Accuracy not specified by manufacturer

22
Conclusions

From the above, it appears that the test procedure indicated does

characterize the delta T "ON" and "OFF" response at ambient and nominal

line voltage conditions. Further, given a controller operating tolerance,

the unit can be evaluated with respect to its adherence to the

specifications provided or assumed.

TEST 2 - RECIRCULATING FREEZE PROTECTION

Eurposa

This test is intended to evaluate the controller's ability to provide

recirculating freeze protection if provided as a controller feature or

option.

Test Conditions

For convenience, this test is performed in conjunction with TEST 1 -

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF") although it may be

performed separately. This test is conducted to simulate conditions of

falling outside temperatures, as determined by the collector sensor, and to

establish the temperature at which the circulating pump will be activated

to provides fluid recirculation in the collector loop to prevent freezing.

When the outside temperature rises and no longer presents a freeze threat,

the temperature which deactivates the circulating pump is also determined.

These pump activation and deactivation points (controlled by the collector

sensor) are measured at varying storage settings and use simulated

temperature inputs (resistances) as established by the appropriate sensor

temperature/resistance table.

23
Since each test is conducted at a fixed storage temperature, it is

convenient to collect the recirculating freeze data in conjunction with

TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF") which is also

conducted at fixed storage temperatures. In effect, after the simulated

collector temperature is lowered to determine the delta T "OFF" condition,

the simulated collector temperature is then lowered further until the

recirculating freeze protection activates the pump and the activating

resistance is noted and recorded. The simulated collector temperature is

then raised until the pump output is again deactivated.

Data points were taken with fixed storage temperature increments of 5°F in

the range between 60 °F and 210 °F corresponding to the points used for TEST

1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"). Because of the

small changes noted in the recirculating freeze protection activation and

deactivation temperatures (see Tables 6 through 10), data taken at 20 °F

storage temperature increments over the entire range would have been

adequate. All tests are performed at ambient conditions with power being

supplied at nominal line voltage.

It should be noted that the tests conducted above used the collector sensor

as the input to the controller freeze protection function. As described

earlier (see SECTION II), the three identical units (LA, IB, and IC) also

had provision for freeze protection activation using an auxiliary sensor.

(This feature was not provided in unit Ila and lib.) The test procedure

for this additional feature is described under TEST 6 - REC I RCULAT I I.'G

FREEZE PROTECTION USING AUXILIARY SENSOR.
Procedure

1. All tests are conducted using the nominal temperature/resistance

table provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Set the storage and collector sensor simulated temperatures

(resistance) to correspond to the lowest storage temperature used in

conducting TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF").

3. Decrease the collector simulated temperature (by increasing the

resistance) until the pump output is activated and record the

resistance corresponding to the recirculating freeze protection "ON"

temperature.

4. Increase the collector sensor simulator (by decreasing the resistance)

until the pump output is deactivated and record the resistance

corresponding to the recirculating freeze protection "OFF"

temperature.

5. Repeat step 2 after increasing the simulated storage temperature by

20 °F (by decreasing the resistance).

6. Repeat steps 3 and 4.

7. Continue this procedure over the storage temperature range used in

conducting TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF").

8. Convert the recorded resistances to operating temperatures using the

nominal temperature/resis tance table appropriate for the simulated

sensor.

9. This test may be conducted in conjunction with TEST 1 - BASELINE

FUNCTIONAL TEST (DELTA T "ON" AND "OFF") by continuing to lower the

simulated collector temperature (after the delta T "OFF" deactivates

the circulating pump) until the simulated temperature is reached where

25
the circulating pump output is again activated by the recirculating

freeze protection circuit. The simulated temperature is again raised

(by decreasing the resistance) until the recirculating freeze

protection is deactivated as described in step 4. Although TEST 1 -

BASELINE FUNCTIONAL TEST (DELTA T

H 0N" AND "OFF") is conducted at 5 °F

storage temperature setting intervals, data for TEST 2 - RECIRCULATING

FREEZE PROTECTION generally need not be taken at intervals less than

20 °F.

Results

The results of the recirculating freeze protection tests conducted on three

identical units from a single manufacturer (Units LA, IB, and IC) are shown

in Tables 6, 7, and 8 respectively. The recirculating freeze protection

tests conducted on the single unit procured from a second manufacturer were

conducted once with the unit in the 18/5 mode and a second time with the

unit set in the 9/4 mode. These are indicated as tests Ila and lib,

respectively, and the results shown in Tables 9 and 10.

For Units IA, IB, and IC, the manufacturer's specifications indicated a

freeze protection "ON" value of 40° + 2 °F and a freeze protection "OFF"

value of 44° ± 2 °F. As can be noted from Tables 6, 7, and 8, all three

units provided recirculating freeze protection "ON" within specification

and were out-of-specification on the high side for the recirculating freeze

protection "OFF" function. The unit procured from the second manufacturer

fell within the ranges indicated in the Ila mode and was out-ofspecification in the lib mode for the higher storage temperature settings.

However, the tolerance range specified by this manufacturer was unclear ind

26
Table 6

RECIRCULATING FREEZE PROTECTION* - UNIT IA

Storage

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Setting Outside In Outside Outside In Outside

Spec* Spec •** Spec. Spec. Spec ,** Spec.

(Low) (High) (Low) (High)

•f <38°F 40°±2°F >42*F <42 °F 44°+2°F >46*F

60 40.5 54.1

65 40.4 53.9

70 40.3 53.7

75 40.3 53.5

80 40.3 53.3

85 40.3 53.2

90 - 40.3 52.9

95 40.3 52.7

100 40.3 52.5

105 40.3 52.3

110 40.3 52.1

115 40.2 51.8

120 40.2 51.6

125 40.2 51.4

130 40.2 51.2

135 40.2 51.0

140 40.2 V 50.8

145 40.2 50.6

150 40.2 50.4

155 40.2 - 50.2

160 40.2 50.1

165 40.2 49.9

170 40.2 49.7

175 40.2 49.6

180 40.2 49.5

185 40.2 49.3

190 40.2 49.2

195 40.2 49.1

200 40.2 49.0

205 40.2 48.9

210 40.2 48.8

* Test run concurrently with TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON" AND "OFF") ** Accuracy specified by manufacturer - Freeze protection ON - 40® +2®F

Freeze protection OFF - 44* +2°F

27 .
Table 7

RECIRCULATING FREEZE PROTECTION* - UNIT IB

Storage

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Setting Outside In Outside Outside In Outside

Spec. Spec .** Spec. Spec. Spec •** Spec . (Low) (High) (Low) (High)

®F <38°F 40 # +2 °F >42°F <42 ®F 44 °±2 °F >46 °F

60 39.9 50.2

65 39.9 49.3

70 39.9 49.3

75 39.9 49.0

80 39.9 48.7

85 39.9 48.4

90 39.9 48.3

95 39.9 48.1

100 39.9 47.9

105 39.9 47.8

110 39.9 47.6

115 39.8 47.5

120 39.8 47.4

125 39.8 47.3

130 39.8 47.3

135 39.8 47.2

140 39.8 47.1

145 39.8 47.1

150 39.8 47.1

155 39.8 47.1

160 39.8 46.9

165 39.8 46.9

170 39.8 46.9

175 39.8 46.8

180 39.8 46.8

185 39.8 46.8

190 39.8 46.8

195 39.8 46.8

200 39.8 46.7

205 39.8 46.7

210 39.8 46.7

* Test run concurrently with TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON" AND "OFF") ** Accuracy specified by manufacturer - Freeze protection ON - 40* +2*F

Freeze protection OFF - 44* +2*F

28
Table 8

RECIRCULATING FREEZE PROTECTION* - UNIT IC

Storage

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Temp

Setting Outside In Outside Outside In Outside

Spec. Spec .** Spec. Spec. Spec .** Spec.

(Low) (High) (Low) (High)

*F <38°F 40 #±2°F >42°F <42 °F 44*±2*F >46 *F

60 39.8 50.2

65 39.8 49.8

70 39.8 49.4

75 39.8 49.1

80 39.8 48.8

85 39.8 48.5

90 39.8 48.3

95 39.7 48.1

100 39.7 47.9

105 39.7 47.8

110 39.7 47.7

115 39.7 47.6

120 39.7 47.4

125 39.7 47.4

130 39.7 47.3

135 39.7 47.2

140 39.7 47.1

145 39.7 47.1

150 39.7 47.1

155 39.7 47.0

160 39.7 46.9

165 39.7 46.9

170 39.7 46.9

175 39.7 46.8

180 39.7 46.8

185 39.7 46.8

190 39.7 46.8

195 39.7 46.8

200 39.7 46.7

205 39.7 46.7

210 39.7 46.7

* Test run concurrently with TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON'’ AND "OFF")

** Accuracy specified by manufacturer - Freete protection ON - 40* +2*F

Freese protection OFF - 44* ^2°F

29
Table 9

RECIRCULATING FREEZE PROTECTION* - UNIT Ha

Storage

Fr eeze Protection ON

'Collector Temp)

Freeze Protection OFF

(Collector Temp)

Setting Outside In Outside Outside In Outside

Spec* Spec.** Spec. Spec. Spec .** Spec . (Low) (High) (Low) (High)

°F <38°F 40 # +2°F >42 °F <42 °F 44 *±2 °F >46 °F

60 41.7 45.8

65 41.7 45.7

70 49.8 45.5

75 I 41.8 45.5

80 41.8 45.4

85 41.9 45.3

90 41.9 45.3

95 41.9 45.2

100

* 41.9 45.2

105 42.0 45.1

110 42.0 45.1

115 42.0 45.1

120 42.0 45.0

125 42.0 45.0

130 42.0 45.0

135 42.0 44.9

140 42.0 44.9

145 42.0 44.9

150 42.0 44.9

155 42.0 44.9

160 42.0 44.9

165 42.0 44.9

170 42.0 44.9

175 42.0 44.9

180 42.0 44.9

185 42.0 44.9

190 42.0 44.9

195 42.0 44.9

200 42.0 44.8

205 42.0 44.8

210 42.0 44.8

* Test run concurrently with TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON" AND "OFF") ** Accuracy assumed the same as Units IA, IB, and IC.

30
Table 10

RECIRCULATING FREEZE PROTECTION* - UNIT lib

Storage

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

lemp

Setting Outside In Outside Outside In Outside

• Spec* Spec.** Spec. Spec. Spec .** Spec.

(Low) (High) (Low) (High)

°F <38°F 40 #±2°F >42 °F <42 °F 44 # +2 °F >46 °F

60 41.7 45.7

65 41.7 45.6

70 41.8 45.5

75 41.8 45.5

80 41.8 45.4

85 41.9 45.3

90 41.9 45.2

95 41.9 45.2

100 41.9 45.1

105 42.0 45.1

110 42.0 45.1

115 42.0 45.0

120 42.0 45.0

125 42.0 45.0

130 42.0 45.0

135 42.0 44.9

140 42.0 44.9

145 42.0 44.9

150 42.0 44.9

155 42.0 44,9

160 42.0 44.9

165 42.1 44.9

170 42.1 44.9

175 42.1 44.9

180 42.1 44.9

185 42.1 44.9

190 42.1 44.9

195 - 42.1 44.8

200 42.1 44.8

205 42.1 44.8

210 42.1 44.8

* Test run concurrently with TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON" AND "OFF")

** Accuracy assumed the same as Units IA, IB, and IC.

31
for purposes of this reports are assumed to be the same as for units IA,

IB, and IC.

Conclusions

From the above it appears that the test procedures adequately indicate the

response of the controller to recirculating freeze protection inputs over

the operating range of the controller. However, for units without

definitive specifications from the manufacturer, no statement can be made

regarding the verification of the manufacturer's claims regarding this

feature.

TEST 3 - CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND "OFF")

Purpose

This test is intended to evaluate the controller's delta T "ON" and "OFF"

response to the tolerance extremes characteristic of the sensor types

specified for use with the controller.

Test Conditions

Tests directly using the nominal temperature/ res is tance table values

provided by the sensor manufacturer have been described under TEST 1 -

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"). These tests were

conducted as if every sensor provided by the manufacturer exactly exhibited

these temperature/ resistance characteristics. In reality, the sensor

tolerances may be ±0.5°F; +1.0°F; some other values, or unspecified.

For the controllers tested, a review of the literature provided with each

controller or obtained separately from the controller manufacturer showed

that the nominal temperature/res is tance table specified for the designated

32
sensors were all equivalent. However, the manufacturer of the three

identical units tested (IA, IB, and IC) provided no sensor tolerances and

the sensor specifications for the second type unit tested (Ila, lib) were

inconsistent in that a tolerance of ±0.5 °F was specified in one piece of

information literature and a tolerance of +0.6 °F in another. (It should be

noted that as an adjunct activity, informal orientation tests conducted on

ten identical sensors shipped with the controllers used for the tests

described in this report exhibited a temperature tolerance spread greater

than +1.0°F. The data for these tests are not included in this report).

Sensor tolerance tests are important in fully understanding the

controller's response in an operational environment. By installing sensors

with a tolerance of +0.5°F in a solar system, the controller would respond

differently from the nominal response characterized under TEST 1 - BASELINE

FUNCTIONAL TEST (DELTA T "ON" AND "OFF") if a high reading sensor (nominal

+0.5°F) were used as the collector sensor and a low reading sensor (nominal

-0.5 °F) used as the storage sensor. A different response would also be

expected if these sensors were reversed in the system; i.e., the high

reading sensor (nominal +0.5°F) used as the storage sensor and the low

reading sensor (nominal -0.5 °F) as the collector sensor.

The tests to assess the controller's response to sensor tolerances were

conducted by constructing a number of modified temperature/ res is tance

tables based on the nominal temperature/resis tance table provided. Since

no consistent sensor tolerance data were indicated by the controller

manufacturer, a tolerance of +0.5 °F and a tolerance of +1.0 °F was used for

the modified tables. These assumed tolerance values were not important

since the primary purpose of this test was to develop an assessment

33
Figure 4

MODIFIED TEMPERATURE/RESISTANCE TABLE

PARTIAL TABLE (32°F - 75°F)

Temp . Nominal Nominal Ncm inal* Nominal Nominal

Minus Minus Plus Plus

°F 1 .0 °F 0.5 °F 0.5°F 1.0°F

32 31748** 32205 32660 33115 —

33 30864 31307 31748 32204 32660

34 30008 30437 30864 31306 31748

35 29178 29594 30008 3 0436 30864

36 28375 28777 29178 29593 30008

37 275% 27986 283 7 5 28776 29178

38 26840 27219 275% 27985 283 75

39 26109 26475 26840 27218 27596

40 25400 257 5 5 26109 26474 26840

41 24711 25056 25400 25754 26109

42 24045 243 7 9 24711 25055 25400

43 23399 23723 24045 24378 24711

44 22771 23086 23399 23722 24045

45 22162 22 467 22771 23085 23399

46 21572 21868 22162 2 2466 22771

47 21000 21287 21572 21867 22162

48 20444 20723 21000 21286 21572

49 19906 20176 20444 20722 21000

50 19382 19645 19906 20175 20444

51 18875 19129 19382 19644 19906

52 18382 18629 18875 19128 193 82

53 17904 18144 18382 18628 18875

54 17440 17673 17904 18143 18382

55 16990 17216 17440 17672 17904

56 16552 16772 16990 17215 17440

57 16127 16340 16552 16771 16990

58 15715 15922 16127 16339 • 16552

59 15314 15515 15715 15921 16127

60 14925 15120 15314 15514 15715

61 14547 14737 14925 15119 15314

62 14180 14364 14547 14736 14925

63 13823 14002 14180 143 6 3 14547

64 13476 13650 13823 14001 14180

65 13139 13308 13476 13649 13823

66 12812 12976 13139 13307 1347 6 67 12494 12654 12812 12975 13139

68 12185 12340 12494 12653 12812

69 11884 12035 12185 12339 12494

70 11592 11739 11884 12034 12185

71 11308 11451 11592 11738 1 1884

72 11031 11170 11308 11450 11592

73 10763 10898 11031 11169 11308

74 10502 10633 10763 10897 11031

75 10248 10376 10502 10632 10763

* See Figure 2 ** All value 8 in ohms

34
methodology and was not to evaluate any specific controller. The resulting

modified t emp e r a t ur e / r e s i s t anc e table along with the nominal

temperature/ res is tance values are shown in Fig. 4. The modified sensor

resistance is shown for tolerances of +1.0 °F, +0.5 °F; -0.5 °F, and -1.0 °F.

The tests conducted were basically the same tests described under TEST 1 -

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF") except the nominal

temperature/resistance values were not used. Instead, the controller's

response to the sensor tolerance was evaluated by using the appropriately

modified temperature/res is tance tables. The first tests assumed a sensor

tolerance of ±0.5°F, with a high reading sensor (+0.5°F) providing the

storage temperature input and a low reading sensor (-0.5 °F) providing the

collector temperature input. The high reading (+0.5 °F) simulated storage

temperature was taken from the +0.5 °F modified temperature/resistance table

and fixed as the storage input. After increasing the simulated collector

temperature to the point where the delta T "ON" was activated, the

resistance reading was converted to a delta T "ON" temperature using the

-0.5°F modified temperature/ resistance table. The simulated temperature

resistance was decreased until a delta T "OFF" resisrance was recorded and

converted to a delta T "OFF" temperature also using the -0.5 °F modified

temperature/res is tance table. This test was then rerun using the low

reading value (-0.5°F) from the modified temperature/res is tance table as

the fixed storage input. The delta T "ON" and "OFF" collector resistance

reading were converted to corresponding temperatures by using the +0.5 °F

modified temperature resistance tables. The two tests were then repeated

using the appropriately modified ±1.0 °F temperature/res is tance tables.
The tests were conducted at an ambient room temperature of approximately

70°F and at a nominal line voltage of 115 VAC at 60 Hertz. Data points

taken at 20 °F intervals starting at 60 °F were deemed sufficient to

characterize the CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND

"OFF")* especially if analyzed in conjunction with the 5°F interval data

used in establishing the controller's response in conducting TEST 1 -

BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF").

Procedure

1. Using both the nominal temperature/ resistance table and the tolerance

limits provided by the controller manufacturer for the sensors

recommended for use with his controller, construct modified nominalplus-tolerance and nominal-minus-tolerance temperature/resistance

tables.

2. Follow the procedure detailed for TEST 1 - BASELINE FUNCTIONAL TEST

(DELTA T "ON" AND "OFF") using the nominal-plus-tolerance table for

the storage input resistance and the nominal-minus-tolerance table for

the collector temperature output.

3. Repeat step 2 using the nominal-minus-tolerance table resistance for

the storage input and the nomina 1 -p 1 us-to 1 eranc e table for the

collector temperature output.

4. Repeat the tests described above after increasing the simulated

storage temperature by 20 °F increments instead of the 5 °F increments

specified under TEST 1 - BASELINE FUNCTIONAL TEST (DELTA "ON" AND

"OFF") .

36
Results

The results of the test for CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA

T "ON" AND "OFF") are shown in Tables 11 through 18. For units IA, IB, and

IC, Table 11 indicates the test results with the simulated storage sensor

set at nominal +0.5 °F and the collector resistances converted to activation

points (for both delta T "ON" or "OFF") at nominal -0.5 °F. Table 12

represents the same data with the simulated storage sensor at nominal -

0.5 °F and the collector at nominal +0.5 °F. Tables 13 and 14 are for

conditions with simulated sensors at +1.0 °F tolerances. When comparing

these results with the data from TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON" AND "OFF"), Tables 1, 2, and 3, the degradation of controller response

with increasing sensor tolerances becomes apparent. Where each of the

units (IA, IB, IC) responded within the +2.5 °F controller specification in

the delta T "ON" mode in the baseline test, the response was moderately

out-of-specification for the +0.5 °F tolerance, and increasingly out-ofspecification for the +1.0°F tolerance. In the delta T "OFF" mode, each of

the units (IA, IB, and IC) were out-of-specification for the baseline test

at the high storage temperature settings (Tables 1, 2, and 3). For the

condition where the storage simulator is set at nominal +1.0 °F and the

collector deactivation temperature determined at nominal -1.0 °F (Table 13),

the delta T "OFF" response is driven further out-of-specification with Unit

IB exhibiting a negative response at a storage setting of 200 °F. The

significance of this negative response is that the solar unit would be

dissipating heat instead of collecting heat under this set of conditions.

In simulating a reversal of the ±1.0 °F tolerance sensors (Fig. 14), for

units IA, IB, and IC, the delta T "OFF" is out-of-specification on the high

side in two units ( IA and IC). This operational condition, over a broad

37
TABLE 11

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND "CFF")

STORAGE +0. 5

°F /COLLECTOR - 0.5 °F

UNIT IA, IB, IC

Storage

Delta T ON Delta ' r OFF

Temp Outside In Outside Outside In Outside

Unit Setting Collector Spec. Spec .* Spec. Collector Spec

Spec .* Spec

Temp • (Low) (High) Temp(Low) (High)

20 °F 5°F

°F °F <17.5°F ±2.5°F >22.5°F °F <2.5°F ±2.5°F >7 .5 "F

60 76.8 16.8 64.8 4.8

80 97.8 17.8 84.9 4.9

100 118.8 18.8 105.0 5.0

IA 120 139.7 19.7 125.0 5.0

20/5 140 160.3 20.3 144.7 4.7

160 180.6 20.6 164.0 4.0

180 200.6 20.6 182.8 2.8

200 220.0 20.0 201.1 1.1

60 76.3 16.3 64.4 4.4

80 97.2 17.2 84.5 4.5

100 118.1 18.1 104.6 4.6

IB 120 139.0 19.0 124.5 4.5

20/5 140 159.6 19.6 144.2 4.2

160 179.9 19.9 163.4 3.4

180 199.8 19.8 182.2 2.2

200 219.3 19.3 200.5 0.5

60 76.9 16.9 64.9 4.9

80 97.9 17.9 85.0 5.0

100 118.8 18.8 105.1 5.1

IC 120 139.8 19.8 125.1 5.1

20/5 140 160.4 . 20.4 144.8 4.8

160 180.8 20.8 164.1 4.1

180 200.7 20.7 183.0 3.0

200 220.2 20.2 201.3 1.3

* Accuracy specified by manufacturer - Delta T ON 20*F + 2.5*F

Delta T OFF 5°F + 2.5°F

38
TABLE 12

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND "OFF")

STORAGE -0.5 °F /COLLECTOR +0.5°F

UNIT IA, IB, IC

Unit

Storage

Temp

Setting

°F

. Delta T ON Delta 1: OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<17.5°F

In

Spec.*

20 °F

+2.5°F

Outside

Spec.

(High)

>22.5°F

Collector

Temp.

°F

Outside

Spec.

(Low)

<2.5°F

In

Spec .*

5 °F

+2 . 5 °F

Outside

Spec

(High)

>7 .5 °F

60 78.8 18.8 66.8 6.8

80 99.8 19.8 86.9 6.9

100 120.8 20.8 107.0 7.0

IA 120 141.7 21.7 126.9 6.9

20/5 140 162.2 22.2 146.6 6.6

160 182.6 22.6 165.8 5.8

180 202.5 22.5 184.6 4.6

200 221.7 21.7 202.8 2.8

60 78.3 18.3 66.4 6.4

80 99.3 19.3 86.5 6.5

100 120.2 20.2 106.5 6.5

IB 120 141.0 21.0 126.5 6.5

20/5 140 161.5 21.5 146.1 6.1

160 181.8 21.8 165.3 5.3

180 201.6 21.6 184.1 4.1

200 220.7 20.7 202.2 2.2

60 78.9 18.9 66.9 6.9

80 99.9 19.9 87.0 7.0

100 120.9 20.9 107.1 7.1

IC 120 141.8 21.8 127.0 7.0

20/5 140 162.3 22.3 146.7 6.7

160 182.7 22.7 166.0 6.0

180 202.1 22.1 184.8 4.8

200 221.8 21.8 203.0 3.0

* Accuracy specified by manufacturer - Delta T ON 20°F + 2.5°F

Delta T OFF 5°F ± 2.5°F

39
TABLE 13

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND "OFF")

STORAGE +1.0 °F /COLLECTOR -1.0 °F

UNIT IA, IB, IC

Unit

Storage

Temp

Setting

°F

Delt a T ON Delta ' [ OFF

Collector

Temp.

°F

Outside

Spec.

(Lov)

<17.5°F

In

Spec.*

20°F

±2.5°F

Outside

Spec.

(High)

>22.5°F

Collector

Temp.

°F

Outside

Spec

(Low)

<2.5°F

In

Spec .*

5*^

+2 . 5 °F

Outside

Spec

(High)

>7 . 5 °F

60 75.8 15.8 63.8 3.8

80 97.0 17.0 83.9 3.9

100 117.9 • 17.9 104.2 4.2

IA 120 139.9 18.9 124.2 4.2

20/5 140 159.4 19.4 143.9 3.9

160 179.7 19.7 163.1 3.1

180 199.5 19.5 181.8 1.8

200 218.7 18.7 200.0 0.0

60 75.2 15.2 63.4 3.4

80 96.4 16.4 83.5 3.5

100 117.3 17.3 103.8 3.8

IB 120 138.2 18.2 123.7 3.7

20/5 140 158.7 18.7 143.4 3.4

160 178.9 18.9 162.6 2.6

180 198.7 18.7 181.2 1.2

200 218.0 18.0 199.5 -0.5

60 75.9 15.9 63.9 3.9

80 97.1 17.1 84.0 4.0

100 118.0 18.0 104.3 4.3

IC 120 139.0 19.0 124.3 4.3

20/5 140 159.6 19.6 144.0 4.0

160 179.8 19.8 163.3 3.3

180 199.7 19.7 182.0 2.0

200 219.1 19.1 200.2 0.2

* Accuracy specified by manufacturer - Delta T ON 20**? +, 2.5*F

Delta T OFF 5°F + 2.5**F

40
TABLE 14

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON1

' AND "CFF")

STORAGE -1.0 °F /COLLECTOR +1.0 °F

UNIT IA, IB, IC

Unit

Storage

Temp

Setting

°F

Delt a T ON Delta r OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<17.5°F

In

Spec.*

20°F

+2.5°F

Outside

Spec.

(High)

>22.5°F

Collector

Temp.

°F

Outside

Spec . (Low)

<2.5°F

In

Spec .*

5°F

±2.5°F

Outside

Spec . (High)

>7.5 °F

60 79.9 19.9 67.9 7.9

80 100.9 20.9 87.9 7.9

100 121.8 21.8 108.0 8.0

IA 120 142.8 22.8 128.0 8.0

20/5 140 163.3 23.3 147.6 7.6

160 183.6 23.6 166.8 6.8

180 203.5 23.5 185.6 5.6

200 222.8 22.8 203.8 3.8

60 79.3 19.3 67.4 7.4

80 100.3 20.3 87.5 7.5

100 121.2 21.2 107.5 7.5

IB 120 142.1 22.1 127.5 7.5

20/5 140 162.6 22.6 147.1 7.1

160 182.9 22.9 166.3 6.3

180 202.7 22.7 185.1 5.1

200 221.9 21.9 203.3 3.3

60 80.0 20.0 67.9 7.9

80 100.9 20.9 88.0 8.0

100 121.9 21.9 108.1 8.1

IC 120 142.9 22.9 128.1 8.1

20/5 140 163.4 23.4 147.8 7.8

160 183.8 23.8 166.9 6.9

180 203.6 23.6 185.8 5.8

200 222.9 22.9 204.0 4.0

* Accuracy specified by manufacturer - Delta T ON 20°F ± 2.5°F

Delta T OFF 5°F + 2.5°F

41
TABLE 15

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON1

' AND "OFF")

STORAGE +0. 5°F /COLLECTOR -0.5°F

UNIT Ila

Unit

Storage

Temp

Setting

°F

Delta T ON Delta ' [ OFF

Collector

Temp.

8F

Outside

Spec.

(Low)

<15.5°F

In

Spec .*

1 8°F

±2.5°F

Outside

Spec.

(High)

>20.5°F

Col lector

Temp

°F

Outside

Spec

(Low)

<2.5°?

In

Spec .*

5°F

+2. 5 °F

Outside

Spec

( High)

> 7 . 5 °F

60 74.8 14.8 64.9 4.9

80 95.1 15.1 85.0 5.0

100 115.7 15.7 104.9 4.9

Ila 120 136.4 16.4 125.1 5.1

18/5 140 157.1 17.1 145.4 5.4

160 177.6 17.6 165.5 5.5

180 197.9 17.9 185.9 5.9

200 217.8 17.8 206.1 6.1

UNIT lib

Unit

Storage

Temp

Setting

°F

Delta T ON Delta 1C OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<6.5°F

In

Spec.**

9°F

+2.5°F

Outside

Spec . (High)

>11.5°F

Col lector

Temp

°F

Outside

Spec

(Low)

<1.5°F

In

Spec .**

4*F

2. 5 *F

Ou t tid

Spec

(High)

> 6 . 5 *F

60 68.1 8.1 64.0 4.0

80 87.6 7.6 84.0 4.0

100 107.5 7.5 103.9 3.9

lib 120 127.8 7.8 124.0 4.0

9/4 140 148.0 8.0 144.3 4.3

160 167.8 7.8 164.4 4.4

180 187.7 7.7 184.7 4.7

200 207.2 7.2 204.8 *> •

00

* DELTA T ON 1 8 °F /DELTA T CFF 5^

** DELTA T ON 9°F/Delta T OFF 4°F

Accuracy not specified by manufacturer

42
TABLE 16

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON” AND "OFF")

STORAGE -0. 5°F /COLLECTOR +0.5°F

UNIT Ha

i

Unit

Storage

Temp

Setting

°F

Delta T ON Delta r OFF

Collector

Temp.

°F

Outside

Spec • (Low)

<15. 5°F

In

Spec .*

18°F

±2.5°F

Outside

Spec

(High)

>20. 5°F

Collector

Temp .

°F

Outside

Spec

(Low)

<2.5°F

In

Spec .*

5°F

+2 . 5 °F

Outside

Spec

(High)

> 7 . 5 °F

60 76.8 16.8 67.0 7.0

80 97.4 17.4 86.9 6.9

100 117.7 17.7 106.8 6.8

Ha 120 138.5 18.5 127.0 7.0

18/5 140 159.0 19.0 147.4 7.4

160 179.5 19.5 167.4 7.4

180 199.7 19.7 187.8 7.8

200 219.5 19.5 207.9 7.9

UNIT lib

Unit

Storage

Temp

Setting

°F

Delta T ON Delta 'C OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<6.5°F

In

Spec.**

9°F

±2.5°F

Outside

Spec.

(High)

>11.5°P

Collector

Temp.

°F

Outside

Spec • (Low)

<1.5°F

In

Spec .**

4°F

+2.5°F

Outside

Spec.

(High)

>6.5°F

60 69.6 9.6 66.1 6.1

80 89.5 9.5 86.0 6.0

100 109.6 9.6 105.9 5.9

lib 120 129.8 9.8 126.0 6.0

9/4 140 150.0 10.0 146.3 6.3

160 169.7 9.7 166.3 6.3

180 189.6 9.6 186.5 6.5

200 209.0 9.0 206.5 6.5

* DELTA T ON 18*^ /DELTA T OFF 5°F

** DELTA T ON 9°F/Delta T OFF 4°F

Accuracy not specified by manufacturer

43
TABLE 17

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON" AND "OFF")

STORAGE +1.0 °F /COLLECTOR -1.0 °F

UNIT Ha

Unit

Storage

Temp

Setting

°F

Delta T ON Delta r OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<15.5°F

In

Spec .*

1 8°F

+2. 5°F

Outside

Spec.

(High)

>20.5°F

Collector

Temp.

°F

Outside

Spec .

( Low)

<2. 5 °F

In

Spec .*

5°F

+2 . 5 °F

Outside

Spec

( High)

>7 . 5 °F

60 73.8 13.8 63.9 3.9

80 94.1 14.1 84.0 4.0

100 114.9 14.9 104.1 4.1

I la 120 135.6 15.6 124.2 4.2

18/5 140 156.3 16.3 144.5 4.5

160 176.6 16.6 164.6 4.6

180 196.8 16.8 184.7 4.7

200 216.8 16.8 204.9 4.9

UNIT lib

Unit

Storage

Temp

Setting

°F

Delta T ON Delta r OFF

Collector

Temp.

°F

Outside

Spec

(Low)

<6.5°F

In

Spec.**

9°F

±2.5°F

Outside

Spec . (High)

>1 1 . 5°F

Col lector

Temp

°F

Outside

Spec • (Low)

<1.5^

In

Spec .**

4°F

2.5°F

Outside

Spec

( High)

> 6 . 5 *F

60 66.5 6.5 63.1 3.1

80 86.6 6.6 83.1 3.1

100 106.8 6.8 103.2 3.2

lib 120 127.0 7.0 123.2 3.2

9/4 140 147.1 7.1 143.5 3.5

160 167.0 7.0 163.6 3.6

180 186.7 6.7 183.7 3.7

200 206.2 6.2 203.7 3.7

**

DELTA T ON 18°F /DELTA T OFF 5°F

DELTA T ON 9 °F /Delta T OFF 4°F

Accuracy not specified by manufacturer

44
TABLE 18

CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T "ON” AND "OFF")

STORAGE -1.0 °F /COLLECTOR +1.0 °F

UNIT Ila

I

Unit

Storage

Temp

Setting

°F

* Delta T ON Delta ' C OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<15.5°F

In

Spec.*

1 8°F

±2.5°F

Outside

Spec.

(High)

>20.5°F

Col lector

Temp •

°F

Outside

Spec

(Low)

<2.5°F

In

Spec .*

5°F

+2 . 5 °F

Outside

Spec

(High)

>7.5 °F

60 77.9 17.9 67.9 7.9

80 98.5 18.5 87.9 7.9

100 118.8 18.8 107.8 7.8

Ila 120 139.5 19.5 128.1 8.1

18/5 140 160.1 20.1 148.4 8.4

160 180.7 20.7 168.5 8.5

180 200.8 20.8 188.9 8.9

200 220.6 20.6 209.0 9.0

UNIT lib

Unit

Storage

Temp

Setting

°F

Delta T ON Delta ' C OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<6.5°F

In

Spec.**

9°F

+2.5°F

Outside

Spec.

(High)

>11.5°F

Collector

Temp •

°F

Outside

Spec.

(Low)

<1.5°F

In

Spec.**

4°F

+2.5°F

Outside

Spec

(High)

>6.5°F

60 70.6 10.6 67.1 7.1

80 90.5 10.5 87.0 7.0

100 110.6 10.6 106.9 6.9

lib 120 130.8 10.8 127.0 7.0

9/4 140 151.0 11.0 147.3 7.3

160 170.7 10.7 167.3 7.3

180 190.7 10.7 187.7 7.7

200 210.0 10.0 207.8 7.8

* DELTA T ON 1 8°F/DELTA T CFF 5°F

** DELTA T ON 9°F/Delta T OFF 4°F

Accuracy not specified by manufacturer

45
temperature range, would turn off the solar unit too soon, negating the

opportunity to add heat to storage.

The test results for TEST 3 - CONTROLLER RESPONSE TO SENSOR TOLERANCE

(DELTA T "ON" AND "OFF") for the single unit procured from a second

manufacturer (Ila and lib) and operating in the 18/5 and 9/4 modes are

shown in tables 15 through 18. As noted, the baseline tests for this unit

(Table 4 and 5), show that for each case the controller falls within the

+2.5 °F controller tolerance assumed. This response is for both the delta T

"ON” and the delta T "OFF" function using the nominal

temperature/res is tance tables. For the simulated storage sensor set at

nominal +0.5 °F and the collector resistance converted to delta T "ON"

activation points at nominal -0.5°F (Table 15), Unit Ila is out-ofspecification at low storage temperature settings. The delta T "OFF"

function remains within specification. In simulating a reversal of the

+0.5°F tolerance sensors (Table 16), the delta T "OFF" for Unit Ila is

outside-of-specif ication at high storage temperature settings while the

other tests showed the controller to operate within specification. The

results for the +1.0 °F tolerance sensors are shown in Tables 17 and 18.

Conclusions

As can be noted from the results, the controller's delta T "ON" and "OFF"

response is a function of the sensor tolerance and that the tests described

above accurately characterize this response. The effects of controller

response using other sensors having different characteristics can also bo

determined using the test concept described above. However, no meaningful

evaluation can be made unless the manufacturer provides the control lor

46
delta T "ON" and "OFF" tolerance along with the tolerances which can be

expected from the sensors to be used with that controller. Although beyond

the scope of this report* an accurate measurement of sensor tolerances must

be independently made if any confidence is to be given to the controller

test results.

TEST 4 - CONTROLLER RESPONSE TO SENSOR TOLERANCE (RECIRCULATING FREEZE

PROTECTION)

Purpose

If provided as a controller feature or option, this test is intended to

evaluate the controller's recirculating freeze protection response to the

tolerance extremes that are characteristic of the sensor types specified

for use with the controller.

Test Conditions

This test was conducted in a manner similar to the tests described under

TEST 2 - RECIRCULATING FREEZE PROTECTION. For convenience, these tests

may also be conducted in conjunction with TEST 3 - CONTROLLER RESPONSE TO

SENSOR TOLERANCE (DELTA T "ON" AND "OFF") or separately. Where TEST 2 -

RECIRCULATING FREEZE PROTECTION uses the nominal temperature/ resis tance

tables to simulate temperature inputs and to convert resistance readings to

temperature activation responses, these tests use the modified nominalplus-tolerance and nominal-minus-tolerance temperature/ res is tance tables

developed for TEST 3 - CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T

"ON" AND "OFF").

47
The tests were conducted with fixed storage temperature increments of 20 °F

in the range between 60°F and 210°F corresponding to the points used for

TEST 3 - CONTROLLER RESPONSE TO SENSOR TOLERANCE (DELTA T '’ON" AND "OFF").

The tests were first conducted with an assumed sensor tolerance of ±0.5 °F,

with a high reading sensor simulator (+0.5 °F) providing the fixed storage

temperature input and a simulated low reading collector sensor (-0.5 °F)

providing the activating element for the recirculating freeze protection

option. Then the tests were conducted with the low reading sensor

simulator (-0.5 °F) providing the fixed storage temperature input and a

simulated low reading collector sensor (+0.5°F) providing the activating

element for the recirculating freeze protection option. The two tests were

repeated using the appropriately modified +1.0 °F temperature/ resistance

tables

The tests were conducted on each of the three identical controllers (IA,

IB» and IC) and conducted separately for each delta T "ON" and "OFF" option

(Ila and lib) for the single controller procured from a second source. The

tests were conducted at an ambient room temperature of approximately 70 °F

and at a nominal line voltage of 115 VAC at 60 Hertz.

Pr.p.cg.duEfi

1. Use the modified nominal-plus-tolerance and the nomina 1 -minustolerance temperature/ resistance tables used for TEST 3 - CONTROLLER

RESPONSE TO SENSOR TOLERANCE (DELTA T "ON1

' AND "OFF").

2. Follow the procedure detailed for TEST 2 - RECIRCULATING FREEZE

PROTECTION using the nominal-plus-tolerance for the storage input

resistance and the nominal-minus-resistance tolerance to convert the

48
simulated collector resistance to pump activation/deactivation

temperatures

3. Repeat step 2 after increasing the simulated storage temperature by

20 °F (by decreasing the resistance).

4. Repeat step 2 using the nominal-minus-tolerance for the storage input

resistance and the nominal-plus-tolerance to convert the simulated

collector resistance to pump activation/deactivation temperatures.

5. This test may be conducted in conjunction with TEST 3 - CONTROLLER

RESPONSE TO SENSOR TOLERANCE (DELTA "ON" AND "OFF") by continuing to

lower the simulated collector temperature (after the delta T "OFF"

circuit deactivates the circulating pump) until the simulated

temperature is reached where the circulating pump output is again

activated by the recirculating freezer protection circuit. The

simulated temperature is again raised (by decreasing the resistance)

until the recirculating freezer protection is deactivated.

Results

The results of the controller response to the effects of sensor tolerance

on the recirculating freeze protection function for three identical units

procured from a single manufacturer (Units IA, IB, and IC) are shown in

Tables 19 and 20 for the +Q.5 °F tolerance sensors and Table 21 and 22 for

the ±1.0 °F tolerance sensors. The results of the same tests on a single

unit procured from a second source, once in the 18/5 mode and a second time

in the 9/4 mode (ila and lib), are shown in Tables 23 through 26.

For Units IA, IB, and IC, the controllers responded to the tolerance tests

in almost the same manner as the tests using the nominal

49
Table 19

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE +0. 5 °F /COLLECTOR -0.5°F

UNITS IA, IB, IC

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec*

(Low)

<38°F

In

Spec •**

40 °+2 °F

Outside

Spec.

(High)

>42 °F

Outside

Spec . (Low)

<42 °F

In

Spec .**

44 °+2 °F

Outside

Spec

(High)

>46 °F

60 39.9 53.6

80 39.9 52.9

100 39.9 52.1

IA 120 39.8 51.2

20/5 140 39.8 50.4

160 39.8 49.6

180 39.8 49.0

200 39.8 48.6

60 39.5 49.7

80 39.4 48.3

100 39.4 47.5

IB 120 39.4 47.0

20/5 140 39.4 46.7

160 39.4 46.5

180 39.4 46.4

200 39.4 46.3

60 39.4 49.8

80 39.4 48.4

100 39.3 47.5

IC 120 39.3 47.0

20/5 140 39.3 46.7

160 39.3 46.5

180 39.3 46.4

200 39.3 46.3

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON" AND "OFF")

** Accuracy specified by manufacturer - Freeze protection ON - 40* +2 *F Freeze protection OFF - 44* ,+2*F

50
CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE -0.5 °F /COLLECTOR +0.5°F

UNITS IA, IB, IC

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec.

(Low)

<38°F

In

Spec.**

40°±2°F

Outside

Spec.

(High)

>42 °F

Outside

Spec.

(Low)

<42 °F

In

Spec .**

44°+2°F

Outside

Spec

(High)

>46 °F

60 40.9 54.6

80 40.9 53.9

100 40.9 53.1

IA 120 40.8 52.2

20/5 140 40.8 51.3

160 40.8 50.6

! 180 40.8 50.0

200 40.8 49.5

60 40.5 50.7

80 40.4 49.3

100 40.4 48.5

IB 120 40.4 48.0

20/5 140 40.4 47.7

160 40.4 47.5

180 40.4 47.4

200 40.4 47.3

60 40.4 50.8

80 40.4 49.4

1 100 40.3 48.5

IC 120 40.3 48.0

20/5 140 40.3 47.7

160 40.3 47.5

i 180 40.3 47.4

200 40.3 47.3

! * Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON” AND "OFF")

** Accuracy specified by manufacturer - Freeze protection ON - 40° +2°F

Freeze protection OFF - 44° .+2

0F
Table 21

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE +1.0°F/COLLECTOR -1.0 °F

UNITS IA, IB, IC

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec

(Low)

<38°F

In

Spec .**

40 °±2 °F

Outside

Spec.

(High)

>42 °F

Outside

Spec.

(Low)

<42 °F

In

Spec.**

44 °+2 °F

Outside

Spec

(High)

>46 °F

60 39.4 53.2

80 39.4 52.5

100 39.4 51.6

IA 120 39.3 50.7

20/5 140 39.3 49.9

160 39.3 49.2

180 39.3 48.6

200 39.3 48.0

60 39.0 49.2

80 38.9 47.8

100 38.9 46.9

IB 120 38.9 46.5

20/5 140 38.9 46.2

160 38.9 46.0

180 38.9 45.9

200 38.9 45.8

60 38.9 49.3

80 38.8 47.8

100 38.8 47.0

IC 120 38.8 46.5

20/5 140 38.8 46.2

160 38.8 46.0

180 38.7 45.9

200 38.7 45.8

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON" AND "CPF") ** Accuracy specified by manufacturer - Freeze protection ON - 40° ±2 °T Freeze protection OFF - 44° .+2*F

52
Table 22

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE -1 »0°F /COLLECTOR +1.0 °F

UNITS IA, IB, IC

Freeze Protection ON Freeze Protection OFF

Storage (Collector Temp) (Collector Temp)

Unit Temp

Setting Outside In Outside Outside In Outside

Spec. Spec .** Spec. Spec. Spec .** Spec

(Low) (High) (Low) (High)

°F <38°F 40 °±2 °F >42°F <42°F 44°±2°F > 46 °F

60 41.4 55.1

80 41.4 54.4

100 41.4 53.5

IA 120 41.3 52.7

20/5 140 41.3 51.8

160 41.3 51.1

180 41.3 50.5

200 41.3 50.1

60 41.0 51.2

80 40.9 49.8

100 40.9 49.0

IB 120 40.9 48.5

20/5 140 40.9 48.2

160 40.9 48.0

180 40.9 47.9

200 40.9 47.8

60 40.9 51.3

80 40.9 49.9

100 40.8 49.0

IC 120 40.8 48.5

20/5 140 40.8 48.2

160 40.8 48.0

180 40.8 47.9

200 40.8 47.1

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON" AND "OFF")

** Accuracy specified by manufacturer - Freeze protection ON - 40° +2°F

Freeze protection OFF - 44° +2°F

53
Table 23

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE +0. 5 °F/ COLLECTOR -0.5^

UNITS Ila, lib

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec*

(Low)

<38°F

In

Spec .**

40 °+2 °F

Outside

Spec.

(High)

>42°F

Outside

Spec . (Low)

<42 °F

In

Spec.**

44 0 +2°F

Outside

Spec

(High)

>46 °F

60 41.3 45.3

80 41.4 44.9

100 41.5 44.7

Ila 120 41.6 44.6

18/5 140 41.6 44.5

160

* 41.6 44.5

180 41.6 44.4

200 41.6 44.4

60 41.2 45.3

80 41.4 45.0

100 41.5 44.7

lib 120 41.6 44.6

9/4 140 41.6 44.5

160 41.6 44.5

180 41.6 44.4

200 41.6 44.4

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON" AND "OFF")

** Accuracy assumed the same as Units IA, IB, and IC.

54
Table 24

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE -0. 5 °F/ COLLECTOR +0.5°F

UNITS Ila, lib

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec.

(Low)

<38°F

In

Spec .**

40°±2*F

Outside

Spec.

(High)

>42°F

Outside

Spec.

(Low)

<42°F

In

Spec .**

44°±2°F

Outside

Spec • (High)

> 46 °F

60 42.3 46.3

80 42.4 45.9

100 42.5 45.7

Ila 120 42.6 45.6

18/5 140 42.6 45.5

160 42.6 45.5

180 42.6 45.4

200 42.6 45.4

60 42.3 46.3

80 42.4 45.9

100 42.5 45.7

lib 120 42.6 45.6

9/4 140 42.6 45.5

160 42.6 45.5

180 42.6 45.4

200 42.6 45.4

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON" AND "OFF")

** Accuracy assumed the same as Units IA, IB, and IC.

55
Table 25

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE +1.0 °F/ COLLECTOR -1.0 °F

UNITS Ila, lib

Freeze Protection ON Freeze Protection OFF

Storage (Collector Temp) (Collector Temp)

TT« «? «= unit Temp

Setting Outside In Outside Outside In Outside

Spec. Spec .** Spec

Spec. Spec .** Spec

(Low) (High) (Low) (High)

°F <38°F 40 °±2 °F >42°F <42 °F 44°+2®F >46 °F

60 40.8 44.8

80 40.9 44.5

100 41.0 44.2

Ila 120 41.1 44.1

18/5 140 41.1 44.0

160 41.1 44.0

180 41.1 43.9

200 41.1 43.9

60 40.8 44.8

80 40.9 44.5

100 41.0 44.2

lib 120 41.1 44.1

9/4 140 41.1 44.0

160 41.1 44.0

180 41.1 43.9

200 41.1 43.9

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON1' AND "CFF")

** Accuracy assumed the same as Units IA, IB, and IC.

56
Table 26

CONTROLLER RESPONSE TO SENSOR TOLERANCE* (RECIRCULATING FREEZE PROTECTION)

STORAGE -1.0 °F/COLLECTOR +1.0 °F

UNITS Ila, lib

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec.

( Low)

<38°F

In

Spec .**

40°±2°F

Outside

Spec.

(High)

>42°F

Outside

Spec.

(Low)

<42 °F

In

Spec .**

44 °+2 °F

Outside

Spec

(High)

>46 °F

60 42.8 46.8

80 42.9 46.4

100 43.0 46.2

Ha 120 43.1 46.1

18/5 140 43,1 46.1

160 43.1 46.0

180 43.1 45.9

200 43.1 45.9

60 42.7 46.8

80 42.9 46.4

100 43.0 46.2

lib 120 43.1 46.1

9/4 140 43.1 46.0

160 43.1 46.0

180 43.1 45.9

200 43.1 45.9

* Test run concurrently with CONTROLLER RESPONSE TO SENSOR SENSITIVITY

(DELTA T "ON" AND "OFF")

** Accuracy assumed the same as Units IA, IB, and IC.

57
TABLE 27

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION)

CHANGES IN VALUE FROM BASELINE

UNIT IA

RECIRCULATING FREEZE PROTECTION "ON"

Collector Tolerance

Temp. Nominal Nominal Nominal Change Change Nominal Nominal Chang e Change

Setting Minus Plus (3)-(2) (4) -(2) Minus Plus ( 7 ) —( 2) (8) -(2)

(1) (2)

.

w

O 0.5°F

(4) (5) (6)

1.0°F

(7)

1.0 °F

(8) (9) (10)

60 40.5 39.9 40.9 -0.6 0.4 39.4 41.4 -1.1 0.9

80 40.3 39.9 40.9 -0.4 0.6 39.4 41.4 -0.9 1.1

100 40.3 39.9 40.9 -0.4 0.6 39.4 41.4 -0.9 1.1

120 40.2 39.8 40.8 -0.4 0.6 39.3 41.3 -0.9 1.1

140 40.2 39.8 40.8 -0.4 0.6 39.3 41.3 -0.9 1.1

160 40.2 39.8 40.8 -0.4 0.6 39.3 41.3 -0.9 1.1

180 40.2 39.8 40.8 -0.4 0.6 39.3 41.3 -0.9 1.1

200 40.2 39.8 40.8 -0.4 0.6 39.3 41.3 -0.9 1.1

RECIRCULATING FREEZE PROTECTION "OFF"

60 54.1 53.6 54.6 -0.5 0.5 53.2 55.1 -0.9 1.0

80 53.3 52.9 53.9 -0.4 0.6 52.5 54.4 -0.8 1.1

100 52.5 52.1 53.1 -0.4 0.6 51.6 53.5 -0.9 1.0

120 51.6 51.2 52.2 —0.4 0.6 50.7 52.7 -0.9 1.1

140 50.8 50.4 51.3 -0.4 0.5 49.9 51.8 -0.9 1.0

160 50.1 49.6 50.6 -0.5 0.5 49.2 51.1 -0.9 1.0

180 49.5 49.0 50.0 -0.5 0.5 48.6 50.5 -0.9 1.0

200 49.0 48.6 49.5 -0.4 0.5 48.0 50.1 -1.0 1.1

(1) Storage temperature resistance determined from appropriately modified tolerance

table i.e. simulated storage temperature set at nominal-plus 0.5*F for nominalminus 0.5 °F controller readings.

(2) Data from Table 6

(3) Data from Table 19

(A) Data from Table 20

(7) Data from Table 21

(8) Data from Table 22

58
TABLE 28

CONTROLLER RESPONSE TO SENSOR TOLERANCE

(RECIRCULATING FREEZE PROTECTION)

CHANGES IN VALUE FROM BASELINE

UNIT Ha

RECIRCULATING FREEZE PROTECTION "ON”

Collector Tolerance

Temp. Nominal Nominal Nominal Change Change Nominal Nominal Change Chang e Setting Minus Plus (3)-<2) (4) -(2) Minus Plus ( 7 ) —( 2) (8) -(2)

0.5°F 0.5°F 1 .0 °F 1.0°F

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)

60 41.7 41.3 42.3 -0.4 0.6 40.8 42.8 -0.9 1.1

80 41.8 41.4 42.4 -0.4 0.6 40.9 42.9 -0.9 1.1

100 41.9 41.5 42.5 -0.4 0.6 41.0 43.0 -0.9 1.1

120 42.0 41.6 42.6 -0.4 0.6 41.1 43.1 -0.9 1.1

140 42.0 41.6 42.6 -0.4 0.6 41.1 43.1 -0.9 1.1

160 42.0 41.6 42.6 -0.4 0.6 41.1 43.1 -0.9 1.1

180 42.0 41.6 42.6 -0.4 0.6 41.1 43.1 -0.9 1.1

200 42.0 41.6 42.6 -0.4 0.6 41.1 43.1 -0.9 1.1

RECIRCULATING FREEZE PROTECTION "OFF”

60 45.8 45.3 46.3 -0.5 0.5 44.8 46.8 -1.0 1.0

80 45.4 44.9 45.9 -0.5 0.4 44.5 46.4 -0.9 1.0

100 45.2 44.7 45.7 -0.5 0.5 44.2 46.2 -1.0 1.0

120 45.0 44.6 45.6 -0.4 0.6 44.1 46.1 -0.9 1.1

140 44.9 44.5 45.5 -0.4 0.6 44.0 46.1 -0.9 1.2

160 44.9 44.5 45.5 -0.4 0.6 44.0 46.0 -0.9 1.1

180 44.9 44.4 45.4 -0.5 0.6 43.9 45.9 -1.0 1.0

200 44.8 44.4 45.4 -0.4 0.6 43.9 45.9 -0.9 1.1

(1) Storage temperature resistance determined from appropriately modified tolerance

table i.e. simulated storage temperature set at nominal-plus 0.5°F for nominalminus 0.5°F controller readings.

(2) Data from Table 9

(3) Data from Table 23

(4) Data from Table 24

(7) Data from Table 25

(8) Data from Table 26

59
temperature/ res is tance tables. All units in each recirculating freeze

protection "ON" test were within the accuracy specified by the

manufacturer. They also were all out-of-specification for the

recirculating freeze protection "OFF" tests except for units IB and IC

which shifted to in-specification values at 160, 180, and 200 °F when the

simulated storage temperature was at nominal-plus 1.0°F and the simulated

collector temperature at nominal-minus 1.0 °F. The tolerance test results

on units Ha and lib, however, varied to a greater degree from the nominal

temperature/resistance tests.

When the test results for the tolerance tests are compared to the nominal

tests and the changes noted, a consistent pattern evolves. Only two sets

of results are shown (Table 27 for unit IA and Table 28 for unit Ila) as

the results for the other units would display similar patterns. As can be

noted from Tables 27 and 28, the changes from nominal approximately

correspond to the tolerance of the collector sensor. This is not

surprising since the collector sensor is the controlling element which

determines the activation and deactivation of the circulating pump.

Conclusions

Because the collector sensor controls the activation and deactivation of

the recirculating freeze protection function, it seems that the behavior of

the controller in this mode can be predicted by adding the collector

tolerance to the results of the tests that use the nominal

temperature/resistance tables. If the nominal tests show that the

controller is activated or deactivated near the center of the ColiriBCI

range and the sensor tolerance limits are narrow, the resulting responses

60
for both high and low tolerance sensors will probably be within

specification. If the nominal tests show that the controller response to

recirculating freeze protection is at the borderline of the specified

controller tolerance] the collector sensor tolerances should drive the

controller out of tolerance for either the high or low tolerance collector

sensor test and closer to the nominal results with the complimentary

tolerance test. If there is any doubt about the controller response

predictability of the analytical method, a single test may be conducted on

the first unit tested and the analytical method used for all subsequent

units of the same type collector. Since the tests are not difficult to

run, especially if conducted in conjunction with TEST 3 - CONTROLLER

RESPONSE TO SENSOR TOLERANCE (DELTA T "ON” AND "OFF"), the evaluation

approach that requires the testing of each unit is a reasonable

alternative.

TEST 5 - STORAGE HIGH TEMPERATURE LIMIT

Purpose

This test is intended to evaluate the controller's storage high temperature

limit response, if provided as a controller feature or option.

Xest Conditions

The storage high limit temperature limit function is intended to protect

the storage tank liquid from reaching high temperatures by cutting-off the

circulating pump when the liquid in the tank reaches a predetermined

temperature. This temperature is set on the three units procured from a single manufacturer (units IA, IB, and IC) by rotating a trimpot knob on

the circuit board until a molded-in arrow on the knob points to the desired

temperature. Temperatures specifically indicated are 105, 120, 140, 180,

61
and 212°F (High Limit Out). Temperature settings between these markings

are made by positioning the arrow on the knob to the approximate setting.

Tests were only conducted with the arrow pointing to one of the discretely

marked setting noted above. The unit procured from a second manufacturer

is adjusted by a series of rocker switches mounted on the controller's

circuit board with setting options of 160 °F, 180 °F, or "OFF". Tests were

conducted at the two storage high temperature limit settings in both the

18/5 mode and in the 9/4 mode (Ila and lib). It should be noted that for

all tests (except this STORAGE HIGH TEMPERATURE LIMIT test) the high limit

option is set to the "OFF" position.

Since this function deactivates the circulating pump, the controller's

simulated operation at the start of this test must be such that the pump is

in the activated mode in order to observe the change. Also, the tests must

be conducted so that the simulated temperatures chosen are not in the range

whereby the pump output is deactivated by a different controller function

such as DELTA T "OFF". The tests are conducted by setting the simulated

storage temperature below the storage high limit test temperature setting

and the simulated collector temperature at the storage high limit test

temperature plus 1.5 times the DELTA T "ON" specified for the controller.

For example, if the storage high limit to be tested is 160 °F and the

controller delta T "ON" is 20°F, the simulated storage sensor is set below

160 °F and the simulated collector temperature at 190 °F (storage high limit

test temperature [160°F] plus delta T "ON" for the controller [20°F] times

1.5 [30°F]). This large delta T will cause the pump output to be

activated. The simulated storage temperature is then raised until the pump

output is deactivated then lowered until the pump output is reactivated.

62
It should be noted that if the simulated collector temperature were set too

low, say 165°F, and the delta T "OFF" for the controller is 5°F, any delta

T "OFF" function deactivating the pump output might be mistaken for the

storage high temperature limit output.

Tests on all units were conducted at an ambient room temperature of

approximately 70 °F and at a nominal line voltage of 115 VAC at 60 Hertz.

Procedure

1. All tests are conducted using the nominal temperature/resistance

tables provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Set the storage sensor simulated temperature at approximately 10 °F

lower than the storage high temperature limit to be tested.

3. Set the collector sensor at a simulated storage temperature calculated

by adding the storage high temperature limit to be tested to 1.5 times

the delta T for the collector.

4. Increase the storage simulated temperature (by decreasing the

resistance) until the pump output is deactivated and record the

resistance corresponding to the storage high temperature limit

deactivation temperature.

5. Decrease the storage simulated temperature (by increasing the

resistance) until the pump output is again activated and record the

resistance corresponding to the storage high temperature limit

reactivation temperature.

6. For units with infinitely adjustable storage high limit temperature

* controls, conduct the initial test at the lowest storage high

63
temperature limit setting as described in steps 2, 3, and 4 above and

each subsequent test at the next higher discrete temperature marking

but not less than every 10°F. Continue testing until a representative

number of tests are performed over the entire range of storage high

temperature limits.

7. For units with discretely settable storage high temperature limits,

test each unit as described in steps 2, 3, and 4 above for each

discrete setting.

8. Convert the recorded resistances to operating temperatures using the

nominal temperature/resistance tables appropriate for the simulated

sensor.

Results

The controllers' response to TEST 5 - STORAGE HIGH TEMPERATURE LIMIT is

shown in Table 29. The specifications for units IA, IB, and IC call for a

±2 °F tolerance for this function. The literature for the unit procured

from a second source (Ila, lib) provide no tolerance limits and, for

purposes of this report, a tolerance of ±2 °F for this unit was assumed. As

can be observed from Table 29, the three identical units procured from a

single manufacturer were generally outside-of-specification for the storage

high temperature limit function (except for the storage high temperature

"OFF" for some of the lower temperature settings for units IA and IC). The

unit procured from a second source was also outside-of-specification for

storage high temperature (PUMP "OFF") but within the assumed specification

for storage high temperature (PUMP "ON") in both the 18/5 and 9/4 mode (II.i

and lib)

64
Table 29

CONTROLLER RESPONSE TO STORAGE HIGH TEMPERATURE LIMIT

UNITS IA, IB, IC; Ila, I lb

Unit

Storage

High

Temp

Limit

Setting

Storage High Temperature

(Pump OFF)

Storage High Temperature

(Pump ON)

Outside

Spec.

(Low)

Setting

<-2°F

In

Spec .*

Setting

±2°F

Outside

Spec

(High)

Setting

>+2°F

Outside

Spec

(Low)

Setting

<-2°F

In

Spec .*

Setting

+2°F

Outside

Spec

(High)

Setting

>+2°F

105 103.9 101.7

IA 120 119.1 115.7

20/5 140 135.8 132.2

180 171.7 163.0

105 101.0 98.8

IB 120 113.3 111.1

20/5 140 130.3 127.9

180 167.9 165.3

105 103.9 101.7

IC 120 116.8 r 114.6

20/5 140 135.8 133.9

180 166.2 163.9

Ila 160 163.8 160.9

18/5 180 184.4 181.5

lib 160 163.8 160.8

9/4 180 184.4 181.7

* Accuracy specified by manufacturer for units IA, IB, and IC is +2°F.

Accuracy not specified for unit Ila, lib - Assumed to be the same as units IA, IB, and IC.

65
Conclusions.

The tests conducted seem to characterize the CONTROLLER RESPONSE TO STORAGE

HIGH TEMPERATURE LIMIT in a reasonable manner. It should be noted that had

the tolerance limits been specified for a wider range (say ±5°F) the units

would have been said to respond better. Since the accuracy of this

function on overall controller operation is not as critical as other

functions (such as delta T "ON" and "OFF"), a controller specification with

different tolerances for each function may be more appropriate instead of a

single controller tolerance for all functions.

TEST 6 - RECIRCULATING FREEZE PROTECTION USING AUXILIARY SENSOR

Purpose

If provided as a special control feature or option, this test is to

evaluate the controller's recirculating freeze protection response using an

auxiliary sensor to control this function. As a by-product of this test

the effect of the auxiliary sensor on the controller's delta T "ON" and

"OFF" response is also evaluated.

Test Conditions

The three identical units procured from a single manufacturer (units IA,

IB, and IC) were provided with the option for using an auxiliary sensor to

activate the recirculating freeze protection feature by moving a jumper

connector on the input to the controller. This feature was not provided on

the controller procured from a second source (unit Ila, 1 1 b ) ; therefore,

this test does not apply to this controller. Tests for units which use the

collector sensor to activate the controllers recirculating freeze

protection function are described under TEST 2 - RECIRCULATING FREEZE

PROTECTION.

66
This test simulates a solar system containing a controller and three

sensors* One sensor determines the storage tank temperature; another the

collector temperature; and the third, the auxiliary sensor, measures the

outdoor ambient conditions. As such, three simulated inputs (decade

resistance boxes) are used. The tests are started by setting each

simulated temperature at a storage test temperature. The simulated

collector temperature is then elevated until the delta T "ON" function is

activated, and then lowered until the delta T "OFF" signal deactivates the

pump output. The delta T "ON11 and "OFF" points are recorded to assess the

effects of the auxiliary recirculating freeze protection sensor circuit, if

any, on the operation of the controller.

The simulated collector temperature is then lowered to the nominal

recirculating freeze protection activation temperature and fixed at this

point to approximate the operating temperature of the collector at

recirculating freeze protection activation by the auxiliary sensor. The

simulated temperature of the auxiliary recirculating freeze protection

sensor is then lowered until the sensor activates the pump output and the

operating point recorded. The simulated temperature is then increased

until the pump output is deactivated and the simulated deactivation

temperature recorded.

The tests are conducted using the nominal temperature/resis tance table and

repeated at storage settings of 20 °F intervals. Tolerance tests are generally not warranted since the controller's response to a variety of

67
changing conditions have been conducted earlier and the controller's

characteristics are generally known by the time this test is performed.

TEST 6 - RECIRCULATING FREEZE PROTECTION USING AUXILIARY SENSOR was

conducted at an ambient temperature of approximately 70 °F with power

supplied at 115 VAC at 60 Hertz.

\ Procedure

1. All tests are conducted using the nominal temperature/ resis tance

table provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Set all the simulated temperatures (resistance) for the storage,

collector, and auxiliary inputs to correspond to the lowest storage

temperature used in conducting the BASELINE FUNCTIONAL TESTS (DELTA T

"ON" AND "OFF").

3. Increase the collector sensor simulated temperature (by decreasing the

resistance) until the pump output is activated and record the

resistance corresponding to the delta T "ON" temperature.

4. Decrease the collector sensor simulated temperature (by increasing the

resistance) until thr pump output is deactivated and record the

resistance corresponding to the delta T "OFF" temperature.

5. Decrease the simulated collector sensor temperature (by increasing the

resistance) to a setting corresponding to the nominal recirculating

freeze protection temperature.

6. Decrease the simulated auxiliary recirculating freeze protection

sensor (by increasing the resistance) until the pump output is

activated and record the resistance corresponding to the rec i rc u 1 a t in,,

freeze protection "ON" temperature.

6 8
7. Increase the simulated auxiliary recirculating freeze protection

sensor (by decreasing the resistance) until the pump output is

deactivated and record the resistance corresponding to the

recirculating freeze protection "OFF" temperature.

8. Repeat step 2 after increasing the simulated storage, collector, and

auxiliary temperatures by 20 °F (by decreasing the resistance).

9. Repeat steps 3 through 7.

10. Continue this procedure over the storage temperature range used in

conducting TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF").

11. Convert the recorded resistances to operating temperatures using the

nominal temperature/resistance table appropriate for the simulated

sensor.

Results

The results of tests for units IA, IB, and IC characterizing the CONTROLLER

RESPONSE USING AUXILIARY SENSOR INPUT (DELTA T "ON" AND "OFF") are shown in

Table 30. If these test results are compared to the results obtained for

TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF"), it will be

noted that the controller's response in both tests are almost identical

(see Table 1). In fact, they do not vary at all for the delta T "ON" tests

and vary only slightly (a few tenths of a °F, at most), at the higher

storage temperature settings. Effectively, this means that for these

controllers, the delta T "ON" and "OFF" function is virtually unchanged

over the controller's overall operating range by the presence of the

auxiliary recirculating freeze protection sensor in the circuit.

The controller's response to recirculating freeze protection using the

69
TABLE 30

CONTROLLER RESPONSE USING AUXILIARY SENSOR INPUT (DELTA T "ON" AND "OFF")

UNIT IA, IB, IC

Delta T ON Delta T OFF

Storage

Temp Outside In Outside Outside In Outside

Unit Setting Collector Spec. Spec .* Spec. Col lector Spec

Spec .* Spec

Temp. (Low)

20 °F

(High) Temp . (Low)

5°F

(High)

°F °F <17.5°F +2.5°F >22.5°F °F < 2. 5 °F +2 . 5 °F >7.5 °F

60 77.8 17.8 65.8 5.8

80 98.8 18.8 85.9 5.9

100 119.8 19.8 106.0 6.0

IA 120 140.7 20.7 126.0 6.0

20/5 140 161.2 21.2 145.7 5.7

160 181.6 21.6 165.0 5.0

180 201.5 21.5 183.9 3.9

200 221.2 21.2 202.3 2.3

60 77.2 17.2 65.4 5.4

80 98.2 18.2 85.4 5.4

100 119.1 19.1 105.6 5.6

IB 120 140.0 20.0 125.5 5.5

20/5 140 160.5 20.5 145.2 5.2

160 180.9 /20.9 164.5 4.5

180 200.7 20.7 183.3 3.3

200 220.4 20.4 201.7 1.7

60 77.8 17.8 65.9 5.9

80 98.9 18.9 86.0 6.0

100 119.8 19.8 106.1 6.1

IC 120 140.8 20.8 126.1 6.1

20/5 140 161.3 21.3 145.9 5.9

160 181.7 21.7 165.1 5.1

180 201.7 21.7 184.0 4.0

200 221.4 21.4 202.4 2.4

* Accuracy specified by manufacturer - Delta T ON 20°F 2.5®F

Delta T OFF 5°F ± 2.5°F

70
Table 31

CONTROLLER RESPONSE USING AUXILIARY SENSOR INPUT* (RECIRCULATING FREEZE PROTECTION)

UNITS IA, IB, IC

Freeze Protection ON Freeze Protection OFF

Storage (Auxiliary Sensor Temp) (Auxiliary Sensor Temp)

Unit Temp

Setting Outside In Outside Outside In Outside

Spec* Spec*** Spec. Spec. Spec .** Spec

(Low) (High) (Low) (High)

®F <38°F 40 °+2 °F >42 °F <42°F 44 °+2 “F >46°F

60 38.6 46.3

80 39.4 46.0

100 39.9 45.8

IA 120 40.2 45.7

20/5 140 40.4 45.7

160 40.5 45.6

180 40.6 45.6

200 40.6 45.6

60 38.5 45.8

80 39.3 45.6

100 39.7 45.4

IB 120 40.0 45.3

20/5 140 40.2 45.3

160 40.3 45.3

180 40.4 45.2

200 40.4 45.2

60 38.5 46.1

80 39.3 45.7

100 39.8 45.6

IC 120 40.0 45.5

20/5 140 40.2 45.4

160 40.3 45.4

180 40.4 45.4

200 40.4 45.4

* Test run concurrently with CONTROLLER RESPONSE USING AUXILIARY SENSOR INPUT

(DELTA T "ON" AND " OFF")

** Accuracy specified by manufacturer - Freeze protection ON - 40° ±2°F

Freeze protection OFF - 44° +2°F

71
auxiliary sensor for the input is shown in Table 31. Each tested unit

operated within the specified tolerance except units IA and IC which was

out-of-specification for the 60 °F storage setting. This is contrasted to

the results obtained for units IA, IB and IC when the collector sensor was

used for TEST 2 - RECIRCULATING FREEZE PROTECTION (Tables 6,7, and 8).

These tables indicate that the Freeze Protection "OFF" function was greatly

out-of-specification for all units. The test results show that for these

specific units, the controller operation using the auxiliary sensor for

recirculating freeze protection is a more desirable mode than using the

collector sensor for this function.

Conclusions.

This test appears to adequately indicate the response of the controller to

recirculating freeze protection when using an auxiliary sensor to activate

this function. It also provides the data to assess the effects, if any, of

the presence of the auxiliary sensor on the delta T "ON" and "OFF"

function.

TEST 7 - PUMP "OFF" BELOW 80 °F

Purpose

If provided as a special control feature or option, this test is intended

to evaluate the controller's PUMP "OFF" BELOW 80 °F function.

Test Conditions

The single controller tested (Unit Ila, lib) was equipped with a PUMP "OFF"

BELOW 80 °F option that is set by a rocker switch on the printed circuit

board. Setting this switch prevents the pump from being activated when the

72
collector is below 80 °F. This feature prevents water circulation at night

after a large amount of water has been consumed or when a reverse

thermosyphon effect would normally cause the pump to turn on. Setting the

recirculating freeze protection switch, however, overrides this option.

The test was performed twice; once with the controller in the 18/5 mode

(Ila) and the second time with the controller in the 9/4 mode (lib). Units

IA, IB, and IC did not have the PUMP "OFF" BELOW 80 °F feature.

The test must be conducted with the pump output activated and care must be

taken to assure that the PUMP "OFF" BELOW 80 °F function is the pump

deactivation stimulus rather than some other functional input such as DELTA

T "OFF". In this regard, the test is conducted with the simulated storage

and collector temperature at 60 °F and the simulated collector temperature

raised to approximately 90 °F. Since the delta T "ON" in the 18/5 mode

(Ila) and in 9/4 mode (lib) is well exceeded with the simuulated collector

temperature at 90 °F and the simulated storage temperature at 60 °F, the pump

output is in an activated state. The simulated collector temperature is

then lowered until the PUMP "OFF" BELOW 80 °F function deactivates the pump

output and the deactivation point recorded. The simulated temperature is

then raised until the pump is again activated and that operating point also

recorded. Since the pump deactivated near 80 °F, it can be assumed that the

PUMP "OFF" BELOW 80 °F function deactivated the pump output and not the

controller's delta T "OFF" circuit. This is because with the simulated

storage temperature set at 60 °F, the delta T "OFF" for the controller in

the 18/5 mode (Ila) would be near 65°F and in the 9/4 mode (lib) near 64°F

and not in the 80 °F range.

73
The PUMP "OFF" BELOW 80 °F tests were conducted at an ambient temperature of

approximately 70 °F with power supplied at 115 VAC at 60 Hertz.

Procedure

1. All tests are conducted using the nominal temperature/resistance

table provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Set the simulated temperature (resistance) for the storage and

collector inputs to 60 °F

3. Increase the collector simulated temperature (by decreasing the

resistance) to a value corresponding to 90 °F, activating the pump

output

4. Decrease the collector simulated temperature (by increasing the

resistance) until the pump output is deactivated and record the

resistance corresponding to the PUMP "OFF" BELOW 80 °F temperature.

5. Increase the collector simulated temperature (by increasing the

resistance) until the pump output is activated and record the

resistance

6. Convert the recorded resistance to operating temperatures using the

nominal temperature/resistance table appropriate for the simulated

sensor.

Results

The PUMP "OFF" BELOW 80 °F test results are shown in Table 32. Since no

tolerance limits were provided for this function, a controller tolerance of

±2 °F were assumed for purposes of this report. The unit was within thi.s

specification in both the 18/5 mode (Ha) and the 9/4 mode (lib). Sincr

this function is not critical to the basic operation of the controller,

74
TABLE 32

PUMP "OFF" BELOW 80 °F

UNIT I la, lib

Pump Output ' ’OFF" Pump Output "ON"

Unit Outside

Spec

(Low)

In

Spec

Outside

Spec

(High)

Outside

Spec

(Low)

In

Spec

Outside

Spec

(High)

<78°F 80 ®+2 °F

'' >82 °F <78°F 80°±2°F >82 °F

I la 18/5 78.9 81.5

lib 9/A 78.9 81.5

75
(such as the delta T "ON" and "OFF" function), perhaps an assignment by the

manufacturer of a tolerance of +5°F may be appropriate.

Conclusions

This test appears to adequately indicate the response of the controller to

the optional PUMP "OFF" BELOW 80 °F function.

SENSITIVITY TO LINE VOLTAGE FLUCTUATION - (AMBIENT)

THE FOLLOWING TESTS WERE CONDUCTED TO EVALUATE THE CONTROLLER'S SENSITIVITY

TO LINE VOLTAGE FLUCTUATION. WITH THE COMPLETION OF THE CONTROLLER'S

FUNCTIONAL TESTS DESCRIBED EARLIER, THE CONTROLLER'S RESPONSE UNDER A

VARIETY OF INPUTS ARE CHARACTERIZED. AS SUCH, IT IS LIKELY THAT ONLY THE

TWO TESTS DESCRIBED BELOW ARE NEEDED TO EVALUATE THE CONTROLLER'S RESPONSE

TO VARIABLE LINE VOLTAGES. THE TESTS WERE CONDUCTED AT AMBIENT CONDITIONS

OF APPROXIMATELY 70 °F.

TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON" AND

OFF)

Purpose?

This test is intended to characterize the controller's delta T "ON" and

"OFF" response to line voltage fluctuation.

lest Conditions

Where TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF") was run

with the input voltage at a nominal 115 VAC at 60 Hertz, these tests are

conducted with the electrical input to the controller at both the low and

high voltage limits specified by the manufacturer. To accomplish this, thr

power input to the controller was supplied through a variac and th.'

76
indicated voltage on the variac confirmed by a separate voltmeter (see Fig.

1). Because the specification for voltage input limits were inconsistent

in the manufacturer's literature, for purposes of this report the tests

were conducted at 90 VAC and later repeated at 130 VAC.

This test is identical to TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON"

AND "OFF") except that data are collected at sensor storage increments of

20 °F instead of 5°F. This increment is sufficient to compare the

controller's line voltage characteristics when used in conjunction with the

more detailed baseline test. Tests were conducted on the three identical

controllers procured from a single manufacturer (units IA, IB, and IC).

Tests were also conducted on the single unit procured from a second source;

once in the 18/5 mode (Ila) and once in the 9/4 mode (lib).

All tests were conducted at an ambient room temperature of approximately

70 °F.

Procedure

1. All tests are conducted using the nominal temperature/ res is tance

table provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Using a variac, or other adjustable voltage device, provide input

power to the controller at the specified low voltage tolerance and

maintain this voltage throughout the test.

3. Set the storage and collector sensor simulated temperatures

(resistance) to correspond to the lowest storage temperature used in

conducting TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF").

77
4 Conduct TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF") by following the procedure detailed for TEST

1 - BASELINE FUNCTIONAL TEST (DELTA T "ON" AND "OFF") except the

storage temperature increments are increased by 20 °F instead of 5 °F.

5. Repeat steps 2 through 4 after resetting the variac or other

adjustable voltage device to the manufacturer's high voltage tolerance

specification.

Results

The results for TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF") are shown in Tables 33 through 36. Table 33 and

34 indicate the test results for units IA, IB, and IC at 90 VAC and 130 VAC

respectively. Tables 35 and 36 indicate the tests result for the single

unit procured from a second source and tested in the 18/5 mode (Ila) and

the 9/4 mode (lib) at 90 VAC and 130 VAC.

The data for TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF") for the three identical units tested (IA, IB, and

IC) at both 90 VAC and 130 VAC (Tables 33 and 34) were compared to the data

collected for these units under TEST 1 - BASELINE FUNCTIONAL TEST (DELTA T

"ON" AND "OFF") at a nominal operating voltage of 115 VAC (Tables 1, 2, and

3). The response of all the controllers were generally identical for all

voltages over the entire range of tested storage temperature settings with

a few delta T readings not corresponding by a few tenths of a degree.

Where the units were out-of-specification in the baseline tests, they were

also out-of-specification in the line voltage fluctuation tests and it c.in

be reasonably assessed that these units are not voltage sensitive over the
voltage range tested at room ambient conditions of approximately 70 °F.

A similar comparison made for unit Ila and lib indicate different results.

In comparing the data for TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE

FLUCTUATION (DELTA T "ON" AND "OFF") at 90 VAC and 130 VAC (Tables 35 and

36) with baseline data conducted at 115 VAC (Tables 4 and 5), it can be

noted that the controller response in the delta T "ON" mode is rather

consistent at all voltages. However, the controller's response in the

delta T "OFF" mode shows a significant difference at the higher storage

temperature tests at 90 VAC. For illustration and ease of analysis, these

data are plotted in Figure 5 for the unit operating in. the 18/5 mode (Ila).

For a controller operating tolerance of ±2.5 °F, it can be seen that the

nominal controller operation is within the ±2.5 °F tolerance for the delta T

"ON" function over the entire operating range for all voltages between 90

VAC and 130 VAC with little variation for the different voltages. For the

delta T "OFF" function, the controller goes out-of-specification at a

storage setting of approximately 165°F when operated at 130 VAC. Although

not plotted, an inspection of the data reveals that the controller exhibits

similar delta T "ON" and "OFF" characteristics when operated in the 9/4

mode (lib).

The above discussion brings to light that no measure of acceptable

performance due strictly to voltage variation is indicated. In effect, if

the controller responds exactly the same when operated at the test voltage,

we can say that the controller is not sensitive to line voltage

fluctuation. If there are different responses to the test voltages,

however, the means of expressing and quantifying these differences is not
TABLE 33

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON” AND "OFF")

90 VAC

UNIT IA, IB, IC

Delta T ON Delta T OFF

Storage

Temp Outside In Outside Outside In Outside

Unit Setting Collector Spec. Spec.* Spec

Collector SpecSpec .* Spec

Temp. (Low) (High) Temp

(Low) (High)

20°F 5 °F °F °F <17.5°F +2.5°F >22.5°F °F < 2. 5 °F ±2.5°F >7.5^

60 77.8 17.8 65.8 5.8

80 98.8 18.8 85.9 5.9

100 119.8 19.8 106.0 6.0

IA 120 140.7 20.7 126.0 6.0

20/5 140 161.2 21.2 145.6 5.6

160 181.6 21.6 164.8 4.8

180 201.6 21.6 183.6 3.9

200 221.2 21.2 201.9 1.9

60 77.2 17.2 65.4 5.4

80 98.2 18.2 85.4 5.4

100 119.1 19.1 105.6 5.6

IB 120 140.1 20.1 125.5 5.5

20/5 140 160.5 20.5 145.2 5.2

160 180.9 20.9 164.4 4.4

180 200.7 20.7 183.3 3.1

200 220.4 20.4 201.4 1.4

60 77.8 17.8 65.8 5.8

80 98.9 18.9 85.9 5.9

100 119.8 19.8 106.1 6.1

IC 120 140.8 20.8 126.0 6.0

20/5 140 161.3 21.3 145.7 5.7

160 181.7 21.7 164.9 4.9

180 201.7 21.7 183.7 3.7

200 221.4 21.4 202.0 2.0

Accuracy specified by manufacturer - Delta T ON 20*^

Delta T OFF 5°F

± 2.5 ®F ± 2. 5 °F

80
TABLE 34

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON" AND "CFF")

130 VAC

UNIT IA, IB, IC

Unit

Storage

Temp

Setting

°F

Delta T ON Delta T OFF

Collector

Temp.

°F

Outside

Spec •

( Low)

<17.5°F

In

Spec .*

20°F

+2.5°F

Outside

Spec.

(High)

>22.5°F

Collector

Temp •

°F

Outside

Spec

(Low)

<2.5°F

In

Spec .*

5°F

±2.5°F

Outside

Spec

(High)

>7 . 5 °F

60 77.8 17.8 65.8 5.8

80 98.8 18.8 85.9 5.9

100 119.8 19.8 106.0 6.0

IA 120 140.7 20.7 126.0 6.0

20/5 140 161.3 21.3 145.7 5.7

160 181.6 21.6 164.9 4.9

180 - 201.6 21.6 183.7 3.7

200 221.2 21.2 202.0 2.0

60 77.2 17.2 65.4 5.4

80 98.2 / 18.2 85.4 5.4

100 119.1 19.1 105.5 5.5

IB 120 140.0 20.0 125.5 5.5

20/5 140 160.5 20.5 145.2 5.2

160 180.9 20.9 164.4 4.4

180 200.7 20.7 183.1 3.1

200 220.3 20.3 201.4 1.4

60 77.8 17.8 65.9 5.9

80 98.9 18.9 86.0 6.0

100 119.8 19.8 106.1 6.1

IC 120 140.8 20.8 126.1 6.1

20/5 140 161.3 21.3 145.8 5.8

160 181.7 21.7 165.0 5.0

180 201.7 21.7 183.8 3.8

200 221.4 21.4 202.2 2.2

* Accuracy specified by manufacturer - Delta T ON 20°F + 2.5°F

Delta T OFF 5°F + 2.5°F

81
TABLE 35

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON” AND "OFF")

90 VAC

UNIT Ha

Storage

Delta T ON Delta 1 OFF

Temp Outside In Outside Outside In Outside

Unit Setting Collector Spec. Spec .* Spec • Collector Spec

Spec .* Spec

Temp. (Low) (High) Temp

(Low) (High)

1 8°F 5 °F °F °F <15.5°F +2.5°F >20.5°F °F < 2. 5 °F ±2.5°F >7.5^

60 75.7 15.7 66.1 6.1

80 96.4 16.4 86.1 6.1

100 116.7 16.7 106.2 6.2

I la 120 137.4 17.4 126.5 6.5

18/5 140 158.1 18.1 147.0 7.0

160 178.5 18.5 167.2 7.2

180 198.8 18.8 187.9 7.9

200 218.9 18.9 208.7 8.7

UNIT lib

Unit

Storage

Temp

Setting

°F

Delta T ON Delta ' r OFF

Collector

Temp.

°F

Outside

Spec • (Low)

<6.5 °F

In

Spec .**

9®F

+2.5°F

Outside

Spec.

(High)

>11.5°F

Collector

Temp

°F

Outside

Spec . (Low)

<1.5*F

In

Spec .**

4°F

2. 5 °F

Outside

Spec

(High)

> 6 . 5 *F

60 68.4 8.4 65.3 5.3

80 88.5 8.5 85.3 5.3

100 108.5 8.5 105.3 5.3

lib 120 128.7 8.7 125.5 5.5

9/4 140 148.9 8.9 146.0 6.0

160 168.8 8.8 166.3 6.3

180 188.6 8.6 186.9 6.9

200 208.2 8.2 207.6 7.6

* DELTA T ON 1 8°F/DELTA T CFF 5°F

** DELTA T ON 9°F/Delta T OFF 4°F

Accuracy not specified by manufacturer

82
TABLE 36

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON" AND "OFF")

130 VAC

UNIT I la

Unit

Storage

Temp

Setting

°F

Delta T ON Delta T OFF

Collector

Temp.

°F

Outside

Spec.

(Low)

<15.5°F

In

Spec.*

18°F

±2.5°F

Outside

Spec.

(High)

>20.5°F

Collector

Temp.

°F

Outside

Spec.

(Low)

<2.5°F

In

Spec .*

5®P

+2 . 5 °F

Outside

Spec

(High)

>7 . 5 °F

60 75.7 15.7 65.8 5.8

80 96.4 16.4 85.8 5.8

100 116.7 16.7 105.8 5.8

Ila 120 137.4 17.4 125.9 5.9

18/5 140 158.0 18.0 146.2 6.2

160 178.5 18.5 166.3 6.3

180 198.8 18.8 186.5 6.5

200 219.0 19.0 206.6 6.6

UNIT lib

Unit

Storage

Temp

Setting

°F

Delta T ON Delta T OFF

Collector

Temp.

°F

Outside

Spec • (Low)

<6.5 °F

In

Spec.**

9°F

±2.5°F

Outside

Spec.

(High)

>11.5°F

Collector

Temp •

°F

Outside

Spec.

(Low)

<1.5°F

In

Spec .**

4°F

±2.5°F

Outside

Spec

(High)

>6.5°F

60 68.4 8.4 65.0 5.0

80 88.5 8.5 84.9 4.9

100 108.5 8.5 104.8 4.8

lib 120 128.7 8.7 124.9 4.9

9/4 140 148.9 8.9 145.2 5.2

160 168.8 8.8 165.2 5.2

180 188.6 8.6 185.2 5.2

200 208.2 8.2 205.3 5.3

* DELTA T ON 1 8 °F /DELTA T OFF 5°F

I ** DELTA T ON 9 °F /Delta T OFF 4°F

Accuracy not specified by manufacturer

83
Figure 5

OPERATING

CHARACTER

ISTICS

AT

VAR

YING

VOLTAGES

(DELTA T

"ON"

AND "

OFF")

UNIT

Ila

84

STORA6E

TEMP

(*F)
presently available.

Conclusions

Data collected using the test procedures described in this section, when

analyzed in conjunction with baseline data seem to adequately characterize

the CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON" AND

"OFF"). It is recommended, however, that methods which quantify response

differences be studied to establish the most appropriate means for

expressing these differences.

TEST 9 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (RECIRCULATING

FREEZE PROTECTION)

Purpose

This test is intended to characterize the controller's recirculating

freeze protection response to line voltage fluctuation.

Test Conditions

This test is conducted in a manner identical to the tests described under

TEST 2 - RECIRCULATING FREEZE PROTECTION with data taken at 20 °F storage

increments. Where TEST 2 - RECIRCULATING FREEZE PROTECTION was conducted

with the controller operating at its nominal input voltage of 115 VAC,

these tests are run with the electrical input to the controller at both the

low and high voltage limits specified by the manufacturer. For purposes of

this report, the variac supplying the power input to the controller was

first set and maintained at 90 VAC and the RECIRCULATING FREEZE PROTECTION

tests conducted. The variac was then reset to 130 VAC and the tests rerun.

A separate voltmeter was used to verify the input voltage and the tests

were conducted at a room ambient temperature of approximately 70 °F.

85
Separate tests were conducted using the three identical controllers (units

IA, IB, and IC) and in the 18/5 mode (Ha) and the 9/4 mode (lib) using the

single controller procured from a second source.

As described under TEST 2 - RECIRCULATING FREEZE PROTECTION, this test may

be conducted separately or, for convenience, may be conducted in

conjunction with TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF").

Procedure

1. All tests are conducted using the nominal temperature/res is tance

table provided by the controller manufacturer for the sensors

recommended for use with his controller.

2. Using a variac or another adjustable voltage device, provide input

power to the controller at the specified low voltage tolerance and

maintain this voltage throughout the test.

3. Conduct TEST 9 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION) following the procedure detailed for

TEST 2 - RECIRCULATING FREEZE PROTECTION.

4. Repeat step 3 after resetting the variac or other adjustable voltage

device to the manufacturer's high voltage tolerance specification.

Results

The data for TEST 9 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION) are shown in Tables 37 through 40.

Tables 37 and 38 present the test data for identical units IA, IB, ami IC

86
at 90 VAC and 130 VAC respectively. Tables 39 and 40 show the test data

for the single unit procured from a second source and tested in the 18/5

mode (Ha) and the 9/4 mode (lib) at 90 VAC and 130 VAC.

The data for TEST 9 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(RECIRCULATING FREEZE PROTECTION) for the three identical units tested (LA,

IB, and IC) at both 90 VAC and 130 VAC (Tables 37 and 38) were compared to

the data from TEST 2 - RECIRCULATING FREEZE PROTECTION conducted for these

units at a nominal operating voltage of 115 VAC (Tables 6, 7, and 8).

Although through an oversight, no data were collected for unit IB operating

at 130 VAC, an inspection of the data collected for the other tests reveals

that the activation temperature (PUMP "ON*') varies no more than 0.3 °F for

all tested operating voltages. The temperature variation for the PUMP

"OFF” signal is greater and the difference is especially apparent during

the 90 VAC tests.

A similar comparison was made for unit Ila and lib. The TEST 9 -

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (RECIRCULATING FREEZE

PROTECTION) data at 90 VAC and 130 VAC (Tables 39 and 40) and the baseline

TEST 2 - RECIRCULATING FREEZE PROTECTION data (Table 9 and 10) show a

response variance of no more than 0.1 °F at all operating voltages.

Although no definition for expressing accuracy has been established (see

TEST 8 - CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON” AND

"OFF"), the results indicate that the unit in each operating mode (Ila and

lib) is very insensitive to line voltage for RECIRCULATING FREEZE

PROTECTION in the 90 VAC to 130 VAC range. The same unit did not perform

as well in the RESPONSE TO LINE VOLTAGE FLUCTUATION (DELTA T "ON" AND

87
CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION* (RECIRCULATING FREEZE PROTECTION)

90 VAC

UNITS IA, IB, IC

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec*

(Low)

<38°F

In

Spec***

40 °±2 °F

Outside

Spec.

(High)

>42°F

Outside

Spec.

(Low)

<42 °F

In

Spec .**

44°+2°F

Outside

Spec

(High)

>46 *F

60 40.2 54.4

80 40.2 53.7

100 40.2 52.8

IA 120 40.2 51.9

20/5 140 40.2 51.1

160 40.2 50.4

180 40.1 49.8

200 40.1 49.3

60 39.8 53.2

80 39.8 52.5

100 39.8 51.7

IB 120 39.8 50.9

20/5 140 39.8 50.1

160 39.8 49.4

180 39.7 48.8

200 39.7 48.4

60 39.8 50.5

80 39.7 49.0

100 39.7 48.2

IC 120 39.7 47.7

20/5 140 39.6 47.3

160 39.6 47.1

180 39.6 47.0

200 39.6 46.9

* Test run concurrently with CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF")

** Accuracy specified by manufacturer - Freeze protection ON - AO* ±2 °T Freeze protection OFF - 44° ,+2*F
CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION* (RECIRCULATING FREEZE PROTECTION)

130 VAC

UNITS IA, IB, IC

r~

Freeze Protection ON Freeze Protection OFF

Storage (Collector Temp) (Collector Temp)

Unit Temp

Setting Outside In Outside Outside In Outside

Spec. Spec.** Spec. Spec. Spec .** Spec.

(Low) (High) (Low) (High)

°F <38°F 40°+2°F >42°F <42 °F 44 °+2 °F >46 °F

60 40.3 53.9

80 40.3 53.2

100 40.3 52.4

IA 120 40.3 51.5

20/5 140 40.3 50.7

160 40.2 50.0

180 40.2 49.4

200 40.2 48.9

60

80

100

IB 120 NO DATA COLLECTED

20/5 140

160

180

200

60 39.8 50.1

80 39.8 48.7

100 39.8 47.8

IC 120 39.8 47.4

20/5 140 39.7 47.1

160 39.7 46.9

180 39.7 46.7

200 39.7 46.6

Test run concurrently with CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF") ** Accuracy specified by manufacturer - Freeze protection

Freeze protection

ON - 40° ±2°F

OFF - 44° +2°F

89
Table 39

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION* (RECIRCULATING FREEZE PROTECTION)

90 VAC

UNITS Ha, lib

Freeze Protection ON Freeze Protection OFF

Storage (Collector Temp) (Collector Temp)

Unit Temp

Setting Outside In Outside Outside In Outside

Spec. Spec.** Spec. Spec. Spec .** Spec

(Low) (High) (Low) (High)

°F <38°F 40°±2°F >42 °F <42 °F 44 °+2 °F >46 ®F

60 41.7 45.6

80 41.8 45.2

100 41.9 45.0

Ha 120 42.0 44.9

18/5 140 42.0 44.8

160 42.0 44.8

180 42.1 44.8

200 42.1 44.7

60 41.7 45.6

80 41.8 45.2

100 41.9 45.0

lib 120 42.0 44.9

9/45 140 42.0 44.8

160 42.0 44.8

180 42.1 44.7

200 42.1 44.7

* Test run concurrently with CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON” AND "OFF")

** Accuracy assumed the same as Units IA, IB, and IC.

90
Table 40

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION* (RECIRCULATING FREEZE PROTECTION)

130 VAC

UNITS Ila, lib

Unit

Storage

Temp

Setting

°F

Freeze Protection ON

(Collector Temp)

Freeze Protection OFF

(Collector Temp)

Outside

Spec*

(Low)

<38°F

In

Spec.**

40 °+2 °F

Outside

Spec.

(High)

>42°F

Outside

Spec.

(Low)

<42 °F

In

Spec .**

44 °+2 °F

Outside

Spec

(High)

>46 °F

60 41.7 45.8

80 41.8 45.4

100 41.9 45.2

Ha 120 42.0 45.0

18/5 140 42.0 45.0

160 42.1 44.9

180 42.1 44.9

200 42.1 44.9

60 41.}. 45.8

80 41.8 45.4

100 41.9 45.2

lib 120 42.0 45.0

9/45 140 42.0 45.0

160 42.0 44.9

180 42.1 44.9

200 42.1 44.9

* Test run concurrently with CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION

(DELTA T "ON" AND "OFF")

** Accuracy assumed the same as Units IA, IB, and IC.

91
"OFF") especially in the highest temperatures at 90 VAC. However, these

results are not inconsistent in that TEST 2 - RECIRCULATING FREEZE

PROTECTION characterizes the controller's response at relatively low

collector operating temperatures although the storage set point was varied

over the entire temperature range.

gflaclusioas

Data collected at specified voltage limits using the test procedures

described in this section, when analyzed with comparable data collected at

the control nominal operating voltage, seem to adequately characterize the

CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION (RECIRCULATING FREEZE

PROTECTION). The lack of an appropriate means to express the degree of

difference in test results, as described in TEST 8 - CONTROLLER RESPONSE TO

LINE VOLTAGE FLUCTUATION (DELTA T "ON" AND "OFF") also applies to these

tests

92
IV. GENERAL CONCLUSIONS

In reviewing the overall results of the tests conducted, it appears that

the controller's response at ambient conditions can be reasonably

characterized using the tests described herein. This is especially true

sinces the controllers response to various inputs is observed to vary

gradually with no abrupt changes, breaks, transitions, or spikes. The

adequacy of these tests can only be evaluated through the additional

testing of a broader spectrum of controller types and also must be

evaluated in a context of the complete test package including the

additional tests to be developed as outlined in the overall test plan.

(See Appendix.) However, the tests detailed above should form a solid

basis for controller evaluation. In addition, the use of decade resistance

boxes proved to be an effective method for testing controller performance.

Specifically, for units tested using the accuracies specified or assumed,

the following conclusions are offered after reviewing the test data:

1. All units tested failed to meet all specified or assumed

specifications

2. In the DELTA T "ON" AND "OFF" mode, the single unit tested in both the

18/5 and 9/4 option (Ila, lib) performed better than any of the three

identical units tested (IA, IB, IC). Of the three identical units

tested, the IB unit was the least accurate.

3. In the RECIRCULATING FREEZE PROTECTION mode. Units IA, IB, and IC were

all outside-of-specif ication for freeze protection "OFF". Unit Ila

was in specification for this function while Unit lib was slightly

out-of-specification at the high temperature settings for freeze

protection "ON".

93
4. All units tested were out-of-specification in varying amounts when

tested for CONTROLLER RESPONSE TO SENSOR TOLERANCE for both DELTA T

"ON" AND "OFF" and RECIRCULATING FREEZE PROTECTION.

5. All units performed poorly in the CONTROLLER RESPONSE TO STORAGE HIGH

TEMPERATURE LIMIT except Unit Ila, lib which was in-specification for

STORAGE HIGH TEMPERATURE (PUMP ON).

6. When Units IA, IB, and IC were operated with an auxiliary sensor to

detect freeze conditions, the DELTA T "ON" AND "OFF" functions changed

little, however, the RECIRCULATING FREEZE PROTECTION response shifted

from completely out-of-specification for freeze protection "OFF" to

in-specification for most storage temperature settings.

7. The PUMP "OFF" BELOW 80 °F function performed in-specification for Unit

Ila, lib.

8. For line voltage range tested, Units IA, IB, and IC were not sensitive

to line voltage variation; however. Unit Ila, lib drifted out-ofspecification at low operating voltages for higher storage temperature

settings in the DELTA T "ON" AND "OFF" mode.

It should be noted that the conclusions listed above would vary if

different specification limits were used. In this regard, it is emphasized

that a complete specification description be provided for each type of

controller so that the results can be adequately interpreted. Also, it is

suggested that the specification vary with function with a tighter

specification prescribed for the important DELTA T "ON" AND "OFF" function

and perhaps a less stringent specification for the secondary features such

as PUMP "OFF" BELOW 80 °F. In addition, the sensor tolerance range should

be integrated with the controller's tolerance range to assure adequ.it.'

94
function over all ranges of operation for all sensors regardless of

location within the solar energy system. Finally, some means to express

differences in CONTROLLER RESPONSE TO LINE VOLTAGE FLUCTUATION needs to be

developed

95
V. REFERENCES

[1] An Analysis of the Effects of Active Solar Energy Sensor Degradation

on Solar Performance; R.B. Farrington and W. Short; SERl/TR-253-21 85;

Solar Energy Research Institute; July 1984.

[2] A Summary and Assessment of Historical Reliability and Maintainability

Data for Solar Hot Water and Space Conditioning Systems; G.J.

Jorgensen; SERI/TR-253-2120; Solar Energy Research Institute, May

1984.

[3] Evaluation and Laboratory Testing of Solar Domestic Hot Water Control

Systems; R.B. Farrington and D. Myers; SERI/TR-254-1 805; Solar Energy

Research Institute; February 1983.

[4] Survey of Failure Modes from 122 Residential Solar Water Heaters;

Prepared by ESG, Inc., Atlanta Georgia for SERI; SERI/ STR-253 -253 1 ;

Solar Energy Research Institute; October 1984.

[5] Research Priorities for Improving the Effectiveness of Active Solar

Hot Water and Space Conditioning Systems; NBSIR 84-2980; R. Dikkers,

W.J. Kennish, C.B. Winn, and W. Huston; National Bureau of Standards;

December 1984.

96
APPENDIX
A previous version of this Test Plan, which constitutes the Appendix of

this document, was distributed to approximately 30 individuals for review

and comment. These individuals encompass a broad spectrum of the solar

energy community and include controller manufacturers, solar system

integrators, universities, national laboratories, government agencies, and

others with interests in solar energy systems. The Test Plan has been

updated to reflect comments received and generally incorporates experience

gained by the testing results reported in this document.

A-ii
TEST PLAN

FOR

DIFFERENTIAL TEMPERATURE CONTROLLERS

USED IN

SOLAR ENERGY SYSTEMS

A-ii i
TABLE OF CONTENTS

Page

TEST PLAN FOR DIFFERENTIAL TEMPERATUE CONTROLLERS USED IN

SOLAR ENERGY SYSTEMS A-iii

1. GENERAL A-l

2. PRE-TEST INSPECTION... A-10

3. FUNCTIONAL TESTS - (AMBIENT) A-10

4. CONTROLLER DISPLAY TESTS - (AMBIENT) A-16

5. INPUT RESISTANCE TO ELECTROMAGNETIC INTERFERENCE

(EMI) TESTS - (AMBIENT) A-18

6. ELECTROMAGNETIC INTERFERENCE (EMI) RADIATION

TESTS - (AMBIENT) A-20

7. SENSITIVITY TO LINE VOLTAGE FLUCTUATION - ( AMBIENT) . .A-21

8. SENSITIVITY TO HIGH VOLTAGE SURGE - (AMBIENT) A-22

9. VIBRATION TESTS - (AMBIENT) A-23

10. STABILITY WITH CHANGING INDOOR ENVIRONMENTAL

CONDITIONS A-24

11. OUTDOOR ENVIRONMENTAL TESTS A-26

12. POST-TEST INSPECTIONS A-27

REFERENCES A-29

FIGURE 1 - RANGE OF CONTROLLER SPECIFICATIONS A-30

A-iv
TEST PLAN FOR DIFFERENTIAL TEMPERATURE CONTROLLERS.

USED IN SOLAR ENERGY SYSTEMS

1

.0

GENERAL

1.1 Nomenclature

1.1.1 The term "controller" as used herein is intended to

mean differential temperature controller (DTC) used in

active solar energy systems.

1 .2 Scope

1 . 2.1

1 . 2.2

The tests identified herein are intended to provide a

recognized test method to verify, or to form the basis

for, the manufacturer's statements contained in his

specification literature regarding controller

performance including such statements addressing

accuracy, stability, environmental application, etc.

Sensors intended for use with the controller are

considered part of this scope only to the extent that

they constitute the input signals which cause the

controller to activate or deactivate.

1.2.3 These tests are generally not intended to predict the

effects of component aging or long term repeated

cycling on controller performance.

1.2.4 These tests are g enera 1 1

y

not intended to be safety

tests evaluating such hazairds as potential fo r fire.

high tempera ture injury. electrical shock, short

A-l
circuit, etc. Safety tests are covered in the

Underwriter's Laboratory (UL) Standards for Safety

[1, 2, 3] and the Canadian Standards Association (CSA)

Safety Standard [4]. Some portions of these safety

tests, however, may be incorporated in the performance

test procedures if they fall within the scope of 1.2.1

above.

1.2.5 The tests identified herein are intended to cover all

controller features, except as described below in

1.2.6. Tests when conducted would be controller

specific with the individual controller functions and

configuration determining tests to be included or

omitted. Definitive features, ranges, tolerances, etc.

not included in the manufacturer's specification

literature generally would not be tested. However, an

alternative to this approach is to test each control ler

feature and compare the results to a default

(predetermined) level if no specification data are

provided .

1.2.6 The tests identified herein are intended to cover

differential temperature controllers including

controllers which also incorporate other features

commonly used to control active solar energy systems

and designated herein as "on/off" controllers. Omitted

from this preliminary scope are proportional

controllers, complex programmable controllers designed

for large solar installations, and those controllers

A-2
performing such functions intended to monitor d irec

solar insolation associated with solar tracking

systems. (Note: Test procedures for proportional

controllers could be added to the scope of this program

or could be developed subsequently).

1.3 Identification of Features to be Tested

1.3.1 A review has been conducted to characterize those types

of controllers currently being marketed and to identify

features available and performance parameters

specified. These data were abstracted from the 1984

Energy Products Specification Guide [5] and a summary

for forty-five (45) controllers is shown in Fig. 1

(page A-30). The summary includes thirty-six (36)

"on/ off" controllers and nine proportional controllers

detailing the property identified, the number of

controllers specifying the property, and the overall

range of extremes for that property. Where the extreme

ranges specified are atypical, a more representative

range is included. These ranges will be referenced

below under each specific test procedure to assure that

when a definitive test procedure is developed the

procedure is adequate in range to accommodate units

being marketed.

1 .4 Sensor Interface

1.4.1 Although the thrust of these functional test procedures

is focused on the solar controller, the control system

A-3
is not complete without the sensing devices which

provide the input signals to allow the controller to

determine when to start or stop the circulating pump,

activate a freeze protection strategy, or protect the

system from excessive temperature. These sensors are

the "front-end" of the control system and must

interface precisely with the controller for effective

operation. The types of sensors available for

temperature input to the controller are: Resistance

Temperature Detectors (RTDs) , Thermistors,

Thermocouples, and Integrated Circuit Temperature

Sensors. Each is described below, however, the RTDs

and the Thermistors are presently the most commonly

used devices for solar control application.

4.1.1 Resistance Temperature Detectors (RTDs) - These

devices typically use platinum, copper, or nickel

wire; increase in resistance with increased

temperature; and generally have a linear

r e s i s t a n c e / t e m p e r a t u r e curve for solar

application. A typical platinum RTD with a 100 ohm

nominal resistance may vary as much as 20 ohms

over its operating range [6].

4.1.2 Thermistors - These devices are generally composed

of sintered particles of metal oxides bound

between two conductive surfaces; decrease in

resistance with increased temperature; have a nonlinear resis tance/ temperature curve; have a high

A-4
internal resistance (1,000 - 35,000 ohms); and

often experience a change in resistance over time

if improperly used [6]. Two common thermistor

types used in solar applications are (1) the 3K

thermistor (3000 ohms at 77 °F [25 °C]) and (2) the

10K thermistor (10,000 ohms at 77 °F [25 °C]).

1.4. 1.3 Thermocouples - These devices are formed by

welding, soldering, or pressing together two

dissimilar metals and require a reference junction

of known temperature for operation; provide an increasing voltage output with increasing

temperature; and can be considered to have a

linear temperature/voltage curve within the solar

application range. A typical thermocouple output

is measured in milli-volts [6].

1.4. 1.4 Integrated Circuit Temperature Sensors - These

devices are integrated circuit chips often in a configuration resembling a transistor; have an

output proportional to the temperature measured;

are generally linear but require additional

electronic components for operation [6].

.4.2 Since the operation of the controller depends on the

input signals received from the sensors, there are several strategies that can be used for controller

testing. One consists of system tests which use the

actual sensing devices for input while others consist

of using a simulated input to activate the controller.

A-5
Each is discussed below.

«4.2»1 Controller Tests Using Sensor Input - These tests

are performed using the sensor provided or

recommended by the manufacturer. The controller's

function would be activated by inserting each

sensor in a controlled temperature liquid bath or

oven. Each functional point tested would require

changing the bath or oven temperature and allowing

the sensor to stabilize at the new temperature.

Tests using this method were performed by Wyle

Laboratories [7] who reported the test method

unusable because of the difficulty in gradually

changing temperatures to activate the controller

functions. These changing temperatures require

precise temperature and power controls on the

baths and despite these controls, there were

problems with temperature gradients and

differences in thermal mass of the sensors and the

calibrated temperature measuring device. The time

required to measure each data point was also

reported as excessive since the temperature of the

bath had to be changed very slowly.

In addition to the above consideration, the tests,

if successful, would only be valid for that

specific sensor/controller combination. If after

installation a sensor failed and an exact

replacement were unavilable, a new sensor with

A-6
different characteristics could trigger the

controller at uncertain activation temperatures.

Also, if aging tests are needed and later

developed for the s ens or/ c on t ro 1 1 er system, the

aging and drift of the sensors should be separated

so as not to obscure the aging effects of the

controller components themselves. Finally, there

would be little impetus for the industry to

produce interchangeable sensors and controllers to

provide the user with maximum flexibility

regarding product application and costs.

.4.2.2 Controller Tests Using Simulated Input - As a

substitute procedure for testing controllers, Wyle

Laboratories used decade resistance substitution

boxes to simulate the sensors [7]. This method

was also used by SERI in their evaluation of Solar

Domestic Hot Water Control Systems [8] and they

reported that they obtained good repeatability and

were able to perform their experiments in a

fraction of the time that would have been required

using the controller's associated sensors and a

temperature bath or oven. However, the test

repeatability should be studied to determine the

criteria for determining the number of times the

parameters should be varied for statistical

conf idence

A-7
Since this method essentially separates the

controller performance from that of the sensor,

some methodology must be used to determine the

res is tor/ temperature curve to be used in

controller testing. Effectively, three

alternatives are available: (1) test the

associated sensors separately in a temperature

bath or oven and develop specific

resistance/ temperature curves for use with each

individual controller; (2) use the specific

resistance/ temperature curves provided by the

sensor manufacturer, or (3) develop a suitable

standardized resistance/ temperature curve for each

type of sensor (3K, 10K, RTD, etc.).

Of the three alternatives identified above, the

approach using the standardized resistance/ temperature curve seems most attractive. Using such a

method would simplify controller testing and could

provide the basis for an independent standard for

sensor performance. Lacking such a standard, a

correlation methodology would need to be developed

to interface the sensor which did not fol low the

"standard" resis tance/ temperature curve.

1.5 Accuracy Representation

1.5.1 As summarized in Fig. 1 the representation of

controller tolerance varied considerably. A sampling

A

is listed below:
(a) ±2.5 °F

(b) ±2 °F over range

(c) ±0.4°F over a 0° to 70 °F range

(d) 10 mV/°F

(e) ±2%

(f) line voltage variation of 10% results in a ±1/2 °F

differential change

(g) ±2 °F "on"; - 0.5° to +1.0 °F "off"

These representations of controller tolerance could be

very confusing or misleading to the purchaser of this

type of equipment. The development of test procedures

for controllers can provide an opportunity to also

standardize the tolerance representation so that tested

controllers could be characterized by specification in

an consistent manner. A representation of controller

tolerance could provide a tight tolerance where

required; i.e., differential control of ±1 °F over a

30 °F to 150 °F range, and perhaps a lesser requirement

for the high limit cut-off; i.e., (180° ±5°F). Also, a

specific tolerance based on degrees (i.e. +2 °F) would

seem to be more desirable than a tolerance based on percent (i.e. ±2%) to avoid changing functional

characteristics over a large operating range.

.6 The test procedures identified in the following sections are generally described in sequence order so that the potentially

destructive tests are performed last. A more definitive sequence

Awill be developed after additional experience is gained and the

test procedures refined.

2.0 PRE-TEST INSPECTION

2.1 Purpose - To inspect the unit to be tested for obvious flaws or deficiency in quality which will prevent the unit from

functioning and to form a baseline for post-test inspections.

2.1.1 Each controller should be inspected prior to testing to

note the physical condition of the unit. This

procedure was proposed by both Wyle [7] and SERI [8] to

detect such manufacturing or design defects as cracks,

abnormal bends, signs of corrosion, mislabled wires,

poorly mounted components, etc. The results of such

visual inspection should be documented as an aid to

characterizing the cause of subsequent failures and as

the basis for evaluating any changes to the controller

components resulting from the tests performed.

3.0 FUNCTIONAL TESTS - (AMBIENT)

3.1 Purpose - To test controller output functions as a response to

specified input signals at varying parameters with the controller

operating at ambient conditions.

3.1.1 Non-ad justab le Unit - These tests would be performed on

controllers that are factory set and not intended to be

field adjusted by the installer or user. If some

controller functions are fixed and some adjustable, the

fixed functions shall be tested as specified below and

the adjustable functions as described in 3.1.2. (Note:

A-10
Test ranges indicated below are tentative and are based

on the ranges shown in Fig. 1. Definitive test ranges

will be developed, as appropriate, along with the

development of the specific test procedure.)

3. 1.1.1 Delta T "on" - This test shall be conducted by

holding one sensor at a fixed temperature and

varying the temperature of the other sensor until

the controller delta T "on" output device (relay

or switch) is activated. This test must be

repeated over the operating range specified by the

manufacturer at increments which will provide the

data to characterize the controller's delta T "on"

response. The form of the test might be as

follows: Using a decade resistance substitution

box, simulate and fix the storage temperature

sensor and vary the collector sensor resistance

until the output device is activated. Repeat with

the storage simulated temperature varied at fixed

intervals. The delta T "on" test range might be

8°F to 20 °F (see Fig. 1) and the simulated storage

temperature varied from 60 °F to 200 °F.

3. 1.1. 2 Delta T "off" - This test shall be conducted by

holding one sensor at a fixed temperature and

varying the temperature of the other sensor until

the controller delta T "off" output device (relay

or switch) is deactivated. This test must be

repeated over the operating range specified by the

A-l 1
manufacturer at increments which will provide data

to characterize the controller's delta T "off"

response. This test might be conducted in

conjunction with the delta T "on" tests (3. 1.1.1)

with the collector sensor resistance simulated by

the decade resistance substitution box varied

until the output device is deactivated. The delta

T "off" test range might be 3 °F to 5 °F (see Fig.

1 ).

3.1. 1.3 High Limit - This test shall be conducted by

increasing the simulated temperature input to the

high temperature sensor until the high limit

output device is activated. The simulated

temperature input would then be decreased until

the output device is deactivated to determine the

"deadband" of the device. In some controllers,

the high temperature limit is activated by the

collector sensor which is a component of the delta

T "on" and "off" sensing system while in other

controllers an independent bimetallic thermal

switch is used [9]. The form of the test for all

sensors except the bimetallic switch might be as

follows: Using a decade resistance substitution

box, simulate the high limit sensor and increment

the equivalent resistance until the controller is

activated (or deactivated, depending on controller

output configuration). Repeat, decreasing the

simulated temperature input in incremental steps

A- 12
until the controller is deactivated (or

activated). The test range for the high limit

function might be 160°F to 212°F (see Fig. 1).

3. 1.1. 4 Low Limit (Freeze Protection) - This test shall be

conducted by decreasing the simulated temperature

input to the low limit (or freeze protection)

sensors or thermal switches until the low limit

output device is activated; and increasing the

simulated temperature input until the device is

deactivated. The form of the test would be

similar to that described for the high limit test

in 3.1.1.3. The test range for the low limit

function might be in the 40 °F - 45 °F range (see

Fig. 1).

3. 1.1. 5 Other Features (Non-Ad justab le) - Tests shall be

developed to evaluate other features specified in

the manufacturer's literature. Such features may

include time delay options, pump "off" below 80 °F,

etc. If appropriate, the operation of this

feature will be evaluated to assess any changes to

primary controller functions.

3.1.2 Adjustable Unit - These tests would be performed on

controllers that are designed to be adjustable in the

field by the installer or the user. Depending on

controller design, the adjustments may be made over the

adjustment range through the use of an adjustable

potentiometer, incremental switch, or by resistor

A- 13
substitution. If some controller functions are adjustable and some fixed, the adjustable functions

shall be tested as specified below and the fixed

functions as specified in 3.1.1.

3. 1.2.1 Delta T "on" - These tests shall be conducted as

described in 3. 1.1.1 for the non-ad j us tab 1 e unit

except they shall be repeated for various settings

over the adjustment range. If the adjustable

component is a variable potentiometer, tests might

be run with the lowest delta T "on" setting and

repeated for a number of increments over the

adjustable range. If the adjustable component is

a step switch or replaceable resistor, tests might

be run at each switch setting or resistor

replacement over the specified operating range.

In addition, the delta T "off" tests and high and

low limit tests may have to be repeated to assess

the effect, if any, of changing the variable delta

T "on" function on the other controller functions.

Typical test ranges for the adjustable delta T

"on" might be 9°F to 20 °F (see Fig. 1). If

appropriate, this test may be repeated for other

adjustable feature settings to determine the

effects of these varying settings on the delta T

"on" operation.

3. 1.2. 2 Delta T "off" - These tests shall be conducted as

described in 3.1.1.2 except they shall be repeated

A- 14
for various settings over the adjustment range as

described in 3. 1.2.1. In addition, the delta T

"on" tests and high and low limit tests may have

to be repeated to assess the effect, if any, of

changing the variable delta T "off" function on

the other controller functions. Typical test

ranges for the adjustable delta T "off" might be

1 °F to 5 °F (see Fig. 1). If appropriate, this

test may be repeated for other adjustable feature

settings to determine the affects of these varying

settings on the delta T "off" operation.

3. 1.2. 3 High Limit - These tests shall be conducted as

described in 3.1. 1.3 except they shall be repeated

for various settings over the adjustment range.

To characterize the high limit on/off activation

points of the controllers, the adjustable

controller element will be set at its lowest

temperature setting, the simulated temperature

input increased until the controller output is

activated, then decreased until deactivated. The

test would be repeated by incrementally raising

the high limit setting. The test range for the

adjustable high limit function might be 160 °F to

212 °F (see Fig. 1).

3. 1.2. 4 Low Limit (Freeze Protection) - These tests shall

be conducted as described in 3. 1.1. 3 except they

shall be repeated for various settings over the

A-l 5
adjustment range to characterize the low limit

(freeze protection) on/off activation points of

the controller. The adjustable controller element

will be set at its highest temperature setting,

the simulated temperature input decreased until

the controller output is activated, then increased

until deactivated. The test would be repeated by

incrementally lowering the low limit (freeze

protection) setting. This test may be performed

in conjunction with the delta T "on" and "off"

test.

3. 1.2. 5 Other Features (Adjustable) - Tests shall be

developed to evaluate other features specified in

the manufacturer's literature. Such features may

include time delay options, pump "off" below 80°F,

etc. If appropriate, the operation of this

feature will be evaluated over its entire

adjustable range to assess and changes to primary

controller functions.

4.0

CONTROLLER DISPLAY TESTS - (AMBIENT)

4.1

Purpose - To test controllers equipped with display readouts to

determine the accuracy of indicated display to measured

temperature (or delta temperature) and to test the operational

characteristics of controllers equipped with switchable

functional controls.

4.1.1 Of the controllers reviewed, 16 were equipped with a

variety of displays and functional controls integral to

A- 16
the controller and five others included features that

allowed the display to be indicated on a unit that was

hard-wired remotely from the controller (see Fig. 1).

The displays included digital temperature readouts and

delta T indications; analog meter readings; functional

operational lights; and, operational selector mode

switches. These tests are included because the

assumption must be made that the installer or user will

depend on the accuracy of the indicated reading for

assessing operational conditions.

4.1.2 The controller display tests shall generally be

conducted, on controllers so equipped, concurrently

with the functional tests described above in 3.0. In

effect, the simulated sensor input setting required to

activate the controller output device (relay or solid

state switch) should register on the display output in

a manner consistent with the stated accuracy of the

readout. In addition, if the display is intended to

continually indicate (or indicate on demand) a sensor

temperature (or a delta temperature), the simulated

sensor resistance should cause a correspondingly

accurate temperature indication on the display.

Because display configurations are unique to individual

manufacturer's controllers, general provisions and

guidelines may be required.

4.1.3 Individual or special tests of functional indicating

lights or operational selector mode switches may not be

A-17
necessary, if, in performing the functional tests

described in 3.0 these display modes or switch settings

are intrinsic to the tests being performed and can be

observed during the conduct of the performance tests. 5.0

INPUT RESISTANCE TO ELECTROMAGNETIC INTERFERENCE (EMI) TEST- (AMBIENT)

5.1

Purpose - To test the controller's response to Electromagnetic

Interference (EMI) picked-up by the sensor leads causing unwanted

controller activation.

5.1.1 Electronic signals emitted from power sources, motors,

communication equipment, etc. can induce "noise"

signals in the sensor leads causing unwanted controller

activation. This is especially true if the sensor

leads exceed 100 ft. although shorter leads under

certain conditions can also exhibit this property. The

term Electromagnetic Interference (EMI) will be used

herein to describe this effect as present usage favors

this more general EMI term in place of the older Radio

Frequency Interference (RFI) term [10].

5.1.2 Current practice for installing sensor leads can reduce

the effects of EMI on the controller. This includes

twisting the sensor leads together at approximately one

twist per inch, using shielded and grounded cable,

routing of wires away from EMI sources such as power

lines and motors, and, when necessary to cross power

lines, by running the sensor leads over the power lines

at right angles. Test procedures will not be developed

A-l 8
to verify the effectiveness of these techniques since

they are external to the controller unit itself.

5.1.3 The thrust of this test procedure will be focused on

controller units that specify that they have intrinsic

EMI protection through internal EMI filtering or other

special circuitry. Tests could be conducted using

various length sensor leads and varying sensor

resistance simulations. Line-voltage (115V) power

lines could be run in parallel with and in close

proximity to the sensor leads and any unwanted

controller output monitored. Other tests might include

an arc discharge or an unfiltered motor operating in

close proximity to the sensor leads. It should be

noted that little research has been documented in the

EMI area as applied to differential controllers used in

solar energy systems.

5.1.4 The tests proposed herein for EMI relates solely to the

susceptibility of the controller to EMI input through

the sensor leads. This should not be confused with EMI

signals produced by the controller itself which would

affect other electronic devices near the controller

such as radios, televisions, or communication

equipment. These signals are produced by certain

proportional controllers and others using electrical

switching devices (as opposed to mechanical relay

switching devices) as part of the controller circuitry.

A-l 9
6.0

ELECTROMAGNETIC INTERFERENCE (EMI) RADIATION TESTS - (AMBIENT)

6.1

Purpose - To test the generation of Electromagnetic Interference

(EMI) produced by the controller.

6.1.1 The controller's electronic circuits under certain

circumstances can produce Electromagnetic Interference

(EMI) which may be transmitted to radio, television,

telephone, and other such devices to cause a noise,

buzz, distortion or other unwanted signal change. Of

particular concern are those controllers that use solid

state switching which can produce EMI if operated in

the delayed firing (phase angle) switching modes (9,

11]. The development of a test procedure for EMI

Radiation Tests will require further study.

6.1.2 This test may be required only for proportional

controllers, however, other on/off controllers may also

emit EMI radiation if their power supplies or other

electrical circuits are not desigped properly. If,

after laboratory study, EMI Radiation is found not to

be a problem with on/off controllers, this test

requirement would be dropped. Never-the-less , if the

scope of this effort is expanded to include

proportional controllers, an EMI Radiation test

procedure, at least for proportional controllers,

should be developed.

A-20
7.0

SENSITIVITY TO LINE VOLTAGE FLUCTUATION - (AMBIENT)

7.1

Purpose - To test the controller's operational stability during

line voltage fluctution conditions.

7.1.1 Differential controllers currently being produced use

solid state circuitry for their power supplies, logic

circuits, amplifiers, etc. These solid state circuits

are sensitive to input voltage changes unless

compensated for by additional stabilizing circuitry.

This test would verify the controller response at

varying input voltage conditions. The test range for

line voltage fluctuation might be 105 to 130 VAC; and

210 to 260 VAC (see Fig. 1). Controllers having the

capability for multi- voltage operation would be tested

in each voltage range.

7.1.2 The controller would be connected to a regulated

adjustable power source. The power source would be

adjusted for the maximum voltage specified for the

controller under test and the following tests

conducted

a. Functional Tests as described in 3.0 including:

1. Delta T "on"

2. Delta T "off"

3. High Limit

4. Low Limit

b. Controller Display Tests as described in section

4.0.

A-21
The power supply shall then be readjusted for the

minimum voltage specified for the controller and the

7.1.3 above tests repeated.

All other tests, described herein, shall be conducted

with the controller being supplied from the locally

available commercial power source.

8.0

SENSITIVITY TO HIGH-VOLTAGE SURGE - (AMBIENT)

8.1

Purpose - To test the controller's susceptibility to damage

induced by high-voltage surges or spikes.

8.1.1 The test procedures would be based on UL 873 [3],

Section 38, Dielectric Voltage Withstand, with

modifications to make the test directly applicable to

differential controllers.

8.1.2 Controllers tested for sensitivity to high-voltage

surge shall be visually inspected for physical changes

as described in 12.0.

8.1.3 After the sensitivity to high-voltage surge test is

conducted and the unit visually inspected, the

controller shall be retested at ambient by conducting

all the functional tests described herein in 3.0 and

4.0 to determine any operational changes resulting from

the high-voltage surge test.

8.1.4 The above tests would not be performed if the

manufacturer makes no comment in his specifications

A-22
regarding his unit's capability to withstand highvoltage surges. 9.0

VIBRATION 9.1 TESTS - (AMBIENT)

Purpose - To test the ability of the controller, if designed to

be pump mounted, to operate under vibrational stress conditions.

9.1.1 Of the controllers reviewed, five controller

9 specifications indicated that they are designed to be

mounted on pumps, valves, or storage tanks (see Fig.

1). These tests address pump mounted controllers and

their ability to operate under vibrational test

conditions. SERI, [8] reported that they conducted

research to determine the actual spectral distribution

of vibrational energy and the total vibrational energy

generated in the operation of actual pumps used in

solar applications. The results were used to test a

controller using a simulation of the operational pump

vibration using a laboratory shaker as the exciter.

SERI concluded that the tested controller continued to

operate without failure or significant deviation in

performance. However, no firm conclusions could be

drawn without additional testing over a longer period

of time to accumulate more data and experience.

9.1 .2 Test procedures will be deve loped using the SERI

experience as a s tar t in g point. Because of the

c omp 1 ex i ty of ttlis type of test pr oc edure and the

relatively small number of pump mounted control lers

marketed, this section may be developed after the

A-23
completion of the remainder of the controller test

procedure and added at a future date.

9.1.3 Controllers subjected to vibration testing shall be

visually inspected for physical changes as described in

12 . 0 .

9.1.4 After the vibration tests are conducted and the unit

visually inspected, the controller shall be retested at

ambient by conducting all the functional tests

described herein in 3.0 and 4.0 to determine any

operational changes resulting from the vibrational

tests

10.0

STABILITY WITH CHANGING INDOOR ENVIRONMENTAL CONDITIONS

10.1

Purpose - To test the controller's operational stability over the

range of indoor environmental temperatures and humidities

specified by the manufacturer.

10.1.1

Controller tests performed at ambient temperature will

be repeated at the specified high and low ambient

temperature using an appropriate environmental chamber.

Humidity tests will also be conducted concurrently at

the relative humidity extremes specified. If humidity

extremes are not specified, tests will be conducted at

a default predetermined relative humidity condition.

Temperature and humidity tests may also be conducted at

intermediate points between the extremes specified, if

appropriate. The test range for ambient temperature

A-24
and humidity might be 32 °F to 120 °F at a range of 5 to

95% relative humidity (see Fig. 1).

10.1.2 The controller shall be placed in the appropriate

environmental chamber and exposed to the test

temperature and humidity. A "soaking" period may be

required to allow the controller to stabilize at the

test condition before beginning the functional tests.

Controllers tested by SERI [8] were environmentally

"soaked" for at least 72 hours while Wyle [7] used a

seven day (168 hour) soak period. Wyle also subjected

controllers to a ten cycle extreme temperature

preconditioning before environmental testing.

10.1.3 With the controller in the environmental chamber and

environmentally stabilized, the following tests shall

be conducted.

a. Functional Tests as described in 3.0 including:

1. Delta T "on"

2. Delta T "off"

3 . High Limit

4. Low Limit

b. Controller Display Tests as described in 4.0.

10.1.4 In addition, consideration shall be given to conducting

the following tests under high and low ambient

temperature and humidity if operational experience or general testing shows that controller sensitivity is

degraded during extreme indoor environmental

conditions

A-25
a. Sensitivity to Line Voltage Fluctuation as described in 7 .0.

b. Sensitivity to High-Voltage Surge as described in

8 . 0 .

10.1.5 After all of the environmental tests are completed, the

controller shall be allowed to return to ambient

conditions and stabilize and be free from any

accumulated moisture resulting from the high humidity

tests. (In their environmental testing report, Wyle [7]

provides for a 24 hr. stability period.) The

controller is then retested at ambient by conducting

all the tests described herein in 3.0 and 4.0 to

determine any operational changes resulting from these

environmental tests.

10.1.6 Controllers tested for stability with changing indoor

environmental conditions shall be visually inspected

for physical changes as described in 12.0.

11.0

OUTDOOR ENVIRONMENTAL TESTS

11.1

Purpose - To test those controllers that are intended for uses

under environmental conditions, other than indoor ambient, as

specified by the manufacturer.

11.1.1

Fig. 1 indicates four controllers designed for

extraordinary environmental conditions including: rain

tight, water tight, and water proof construction.

These environmental operating conditions would have to

be defined carefully before an adequate test procedure

A-26
is developed. Several tests have been identified and

others will have to be researched to develop

appropriate test procedures applicable to solar

differential controllers.

11.1.2 Tests identified include Rain Tests (UL 429 [12]) and

Salt Spray (Fog) Testing (ANSI/ASTM B 117-73 [13]). If

existing test methods cannot be adopted or are

inadequate for the purposes intended, new test methods

may have to be developed. Other outdoor environmental

tests might include dust, ice, and extreme high and low

outdoor temperature tests similar to the high and low

indoor temperature environmental tests described in

10.0. Consideration shall also be given to conducting

the outdoor and indoor high and low temperature tests

concurrently if the specified ranges are compatible.

11.1.2 After outdoor environment testing, the controller units

shall be visually inspected for physical changes as described in 12.0 and retested at ambient for

functional operation as described in 3.0 and 4.0.

12.0

POST-TEST INSPECTIONS

12.1

Purpose - To inspect the controller after a severe, potentially

damaging test to determine any permanent damage to the controller

and to aid in assessing future controller performance.

12.1.1

A post-test visual inspection shall be made of the

controller to determine changes in component condition

such as cracks or corrosion, which would adversely

A-27
effect the long term operation of the controller. This

inspection would use the information documented during

the Pre-Test Inspection (2.0) as a baseline for

comparison. It should be noted that this assessment of

long term operation is not meant to be a definitive

determination of the long term controller reliability

or operational life expectation.

12.1.2 Post-test visual inspection shall be performed after

the following tests are complete.

a. Sensitivity to Line Voltage (7.0)

b. Sensitivity to High Voltage Surge (8.0)

c. Vibration Tests (9.0)

d. Stability With Changing Indoor Environmental

Conditions (10.0)

e. Outdoor Environmental Test (11.0)

A-28
REFERENCES

[1] Underwriters Laboratory - Standard for Safety; UL 353; Limit Controls.

[2] Underwriters Laboratory - Standard for Safety; UL 508; Industrial

Control Equipment.

[3] Underwriters Laboratory - Standard for Safety; UL 873; Temperature

Indicating and Regulating Equipment.

[4] Canadian Standards Association; CSA Standard C22.2 No. 24-1981;

Temperature Indicating and Regulating Equipment.

[5] Energy Products Specification Guide - Conservation, Solar, Wind and

Photovoltaics; 1984; SolarVision, Inc.; Solar Age Magazine.

[6] NBS Building Science Series 153; Calibration of Temperature

Measurement Systems Installed in Buildings; C.W. Hurley and

J.F. Schooley; National Bureau of Standards; January 1984.

[7] Reliability and Performance Evaluation of Temperature Differential

Controllers; G.T. Meares and R. Barber; Wyle Laboratories Study

Conducted for the National Bureau of Standards; April 30, 1981.

[8] Evaluation and Laboratory Testing of Solar Domestic Hot Water Control

Systems; R.B. Farrington and D. Myers; SERI/TR-254-1 805; Solar Energy

Research Institute; February 1983.

[9] Differential Controls for Domestic Hot Water Systems; The Solar

Controls Book; Section 21; J. Klima; Solar Training Publications;

Lakewood, CO; 1982.

[10] Noise Reduction Techniques in Electronic Systems; H.W. Ott; John Wiley

and Sons; 1 976.

[11] National Electrical Manufacturers Association (NEMA); Standard 11-11-

1976.

[12] Underwriters Laboratory - Standard for Safety; UL 429; Electrically

Operated Valves.

[13] American National Standard/American Society for Testing Materials;

ANSI/ASTM B117-73 (Reapproved 1979); Standard Method of Salt Spray

(Fog) Testing.

A-2 9
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A- 31
PROPORTIONAL

CONTROLLER

!

OVERALL

MNGE

[TYPICAL.

RANGE]

117

-

120

VAC

220

VAC

24

VAC

2.5

-

40

Watts

[2.5

- 7

Watts]

60

Hz

50/60

Hz

Relay

Solid

State

<r

i PO

120

VAC

24

VAC 3-8

Amps

Domestic

hot

water

Space

heat

(air)

Space

heat

(liquid)

Pool/SPA

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A-32
UBS.114A (REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 86-3346

2. Performing Organ. Report No. 3. Publication Date

April 1986

4. TITLE AND SUBTITLE

INITIAL TEST RESULTS AND TEST PLAN FOR DIFFERENTIAL TEMPERATURE CONTROLLERS

USED IN SOLAR ENERGY SYSTEMS

5. AUTHOR(S)

Joseph Greenberg

6. PERFORMING ORGANIZATION (If joint or other than NBS, see instructions)

national bureau of standards

department of commerce

WASHINGTON, D.C. 20234

7.

Contract/Grant No. DE-AI01-76PR06010

8.

Type of Report & Period Covered

Final

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City, State, ZIP) U. S. Department of Energy

Office of Solar Heat Technologies

Solar Buildings Technology Division

Washington, DC 20585

10.

SUPPLEMENTARY NOTES

| | Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

The initial test results and procedures used to conduct tests on differential

temperature controllers used in solar energy systems are discussed. These

tests were performed on generally non-adj us table, non-display units and include

the following functional tests conducted at ambient conditions: delta T "on"

and "off"; recirculating freeze protection with and without auxiliary sensor;

controller response to sensor sensitivity; storage high temperature limit; and

pump "off" below 80 C. Controller sensitivity to line voltage variation tests

were also conducted at ambient conditions and include: delta T "on" and "off"

and recirculating freeze protection. The controller test fixture is also

described along with the recommended use of decade resistance boxes to simulate

thermistor inputs. An overall test plan is also included as an appendix to the

report.

14 KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

Differential temperature controllers; functional tests; sensors; solar energy;

test plan; test procedures; thermistors; voltage fluctuation tests

13. availability

Unlimited

For Official Distribution. Do Not Release to NTIS

[^] Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

[X] Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

144

15. Price

$ 16.95

USCOMM-OC 8043-P80