SERI/STR-253-2531 

UC Category: 59a 

DE85000541 

Survey of Failure Modes from 

122 Residential Solar 

Water Heaters 

ESG, Inc. 

Atlanta, Georgia 

October 1984 

Prepared under Subcontract No. HK-3-03128-1 

SERI Technical Monitor: Charles Kutscher 

Solar Energy Research Institute 

A Division of Midwest Research Institute 

1617 Cole Boulevard 

Golden, Colorado 80401 

Prepared for the 

U.S. Department of Energy 

Contract No. DE-AC02-83CH10093 
FOREWORD 

Thi s report was prepared under the overall sponsorshi p of 

the Office of Solar Heat Technologies of the U. S. 

Department of Energy . We would like to acknowledge the 

excellent cooperation of the individual homeowners and the 

many industry dealers who participated in the effort which 

also involved a field monitoring program conducted over an 

extended period of time . At ESG, Inc., special recognition 

is due William M. Jones, S. M. Blanchard, and the entire 

Data Analysis staff . At SERI, Charles F. Kutscher provided 

program guidance for the effort . 

ESG, Inc . 1 984 

Approved for 

Solar Energy Research Institute 

ohn P. Thornton, Manager 

Thermal Systems and Engineering Branch 

Solar Heat Research Division 

iii 
INTRODUCTION 

The Department of Energy I s nat i ona 1 solar Active Heat i ng and Cool i ng (MAC ) 

Program funds research to develop a technical base for the private sector to 

develop affordable, reliable solar technologies to replace non-renewable 

energy resources. The Systems Effectiveness Research (SER ) program is a subelement of the overall AHAC Program that is specifically concerned with the 

reliability and operational performance of MAC systems, components, and 

materials. As part of the SER program, SERI funded ESG, Inc., to study reliability problems in their residential domestic hot water field test program. 

This report contains the results of a detailed survey of operating systems 

aimed at determining which specific reliability problems occurred and their 

frequency of occurrence. To gather this information, questionnaires were sent 

to both homeowners and installers covering 122 systems. Results were categori zed accord i ng to problem severi ty , 1 ocat i on, system type, 1 ength of system 

operation, and time of the year. 

This study indicated that approximately 47% of the systems had at least one 

reliability problem over a two-year period. Flat-plate collector and storage 

systems were found to be hi gh ly re 1 i ab 1 e, and most causes of improper system 

operat ion could be traced to i nsta 11 at ion problems. Ora i ndown systems were 

the least reliable system type largely because of the failure of draindown 

valves, while drainback designs had the greatest reliability. Differential 

controllers were responsible for the largest number of failures that resulted 

in a repair cost in excess of $50 to the homeowner. 

Thi s report was reviewed by C. Kutscher, R. Farri ngton, G. Jorgensen, and 

w. Short, all of SERI. 

iv 
I. 

II. 

T ABLE OF CONTENTS 

BACKGROUND AND OBJECTIVES . ... ..... .......................... . 1 

DEVELOPMENT OF S URVEY . ... ............. ..... .... ............. . 2 

- Homeowner Survey Forms Package . . . ... ....................... 2 

- Installer Survey Forms Package . ... ........... .............. 3 

- Survey Responses........ ......... .......................... 4 

I I I. CATEGORIES FOR DATA REDUCT ION AND ANALySIS . ...... ............. 6 

- Initial Discussion •••••••• �................................ 6 

- Categories of System Problem Areas .... ...... .............. . 6 

IV . EFFECTS OF PROBLEMS ON HOMEOWNER . ..... ........................ 10 

V. REPORTED CAUSES OF SYSTEM PROBLEM AREAS . .................. .... 11 

- Initial Discussion...... ............. ...... ......... . ...... 11 

- Installation Related Problems . ......... . ..... .............. 11 

- Controller Related Problems • • ••• •••. •••••• •••••••••• ••••.•• 13 

- Sensor Related Problems . . .................................. 13 

V I. OPERAT IONAL TIME WHEN PROBLEMS OCCURRED . .... .... ...... ... ..... 14 

- System Operational Periods ........ ........ . . ............... 14 

- Seasonal Variations . . . ............ ......... ........ ....... . 15 

V II. CONCLUSIONS ... ...... ..... . . ............................... .... 16 

APPENDIX A - PROGRAM PARTICIPAN TS SURVEY FORMS PACKAGE ••••• •••• ••••• A-1 

- Homeowner Survey Forms Package • • ••••••••••••••••••••••••..• A-2 

- Installer Survey Forms Package .� ••• ••••• • • ••••••••••••••••• A-9 

APPENDIX B - INSTALLER FIELD EXPER IENCES S URVEY RES ULTS .••••••• ••••• B-1 

v 
Ie BACKGROUND AND OBJECTIVES 

In mid 1 981 , the U. S. Department of Energy began a program for monitoring 

the performance of a number of residential solar hot water systems in the 

southeastern Uni ted States. Thi s program was i ni ti ated through the Southern 

Solar Energy Center and later continued by ESG, Inc . During this effort 

perfonnance data were collected on over 160 systems with emphasis on answering 

basic questions concerning the overall efficiency and cost effectiveness of the 

systems. 

However, it became obvious that a considerable body of information was 

also available concerning the reliability and maintainability (R&M) of these 

systems . This resulted not only because of the direct data collection process 

which involved the homeowners, but because of the very substantial involvement 

of the industry installers who participated in the program. Thus, a 

suppl emental effort was conducted wi th sponsorshi p through the Sol ar Energy 

Research Insti tute of the U. S. Department of Energy to coll ect and analyze 

the data related to R&M. This covered direct survey of the participants and 

industry members i nvol ved in the performance moni tori ng program. The survey 

and the resulting data are presented herein. 

The overall objective of the survey was to gather detailed information 

concerning system operational reliability and maintainability. Information 

concerning failure modes, operational problems, installer experiences, user 

comments, etc. was accumulated for analysis purposes. 

The major objectives of the survey were as follows: 

1) To determi ne the major areas where system probl em areas occurred 

during the monitoring period. 

2) To determine the degree that prevalent problem areas differ for 

specific system types, components, geographic locations, etc. 

1 
3) To gather sufficient and detailed information on system R&M problem 

areas so as to categorize identified problem areas with a high 

level of confidence. 

4) To gather secondary information, related to homeowner and installer 

experience, etc., from the program participants. 

I Ie DEVELOPMENT OF S URVEY 

ESG placed a cons i derab 1 e amount 0 f importance on the development of an 

effective means for gathering the R&M data from the field test systems . It 

was considered imperative to develop a survey format which would gather 

factual information concerning failure modes while not appearing overwhelming 

. to participants in the magnitude of requested information. 

Two groups of program parti cipants were surveyed . The groups were the 

installer participants and the homeowner participants . Specialized surveys 

were developed and di stributed by mail to each group. The survey forms were 

pri marily desi gned to i dent; fy and gather data on probl ems whi ch occurred 

during the performance monitoring periods . As mentioned, secondary data were 

also gathered on use patterns of the homeowners and the overall R&M 

experiences of the installers. 

Homeowner Survey Forms Package 

The homeowner survey package was di stri buted to 143 homeowners . The 

total survey package is found in Appendix A. As shown, the survey package 

had two parts, Data Form A and Data Form B. 

Form A was totally concerned with identifying and gathering detailed 

i nformati on on system fai lure modes and other R&M probl ems . The major 

areas addressed by Form A were the following: 

1) What were the system problems? 

2) How were the problems noticed? 

3) What maintenance was performed? 

2 
4) What components were replaced? 

5) What were the known causes of the problems? 

6) What were the costs of problems to the homeowner? 

Each homeowner was requested to compl ete one Data Form A for each 

problem that was realized by their system. Included in the data package 

was the homeowner's latest Monthly Summary Report (MSR). The MSR is a 

performance report which includes a list of problems reported during the 

field test program. The 1 ist was provided to help the homeowner review 

the events and· dates relating to system problems. Of course, the 

homeowner was asked to include any problems not listed on the MSR. 

Data Form B for the homeowner parti ci pants was desi gned to gather 

general information on the interaction of the homeowners with their solar 

water heater. Thi s secondary i nformati on became useful to the analysi s 

efforts because homeowners coul d be categori zed accordi ng to hot water 

usage profiles and general attitudes toward their system. 

Al so i ncl uded wi th the forms package was a cover 1 etter and an 

example listing of system R&M problem areas. The cover letter included 

i nformati on concerni ng the importance of the survey effort as well as 

directions to the homeowner for properly completing the forms package. 

The example 1 isting of system R&M problem areas aided the homeowner in 

identifying types of system problems. 

Installer Survey Forms Package 

The install er survey forms package al so had two parts, Data Form A 

and Data Form B. Thirty-six installers were distributed the forms 

package, see Appendix A. The installer's Data Form A was very similiar to 

the homeowner's Data Form A. Installers were requested to complete a Data 

Form A for each problem encountered by their monitored systems. 

3 
Data Fonn B was uti 1 i zed to gather data on the total fi el d 

experiences of the installers. 

system components and related 

Included in Data Form B was a listing of 

problem areas . The installers were 

requested to rank the system components and problem areas in the order of 

frequency of occurrence. This information allowed for comparisons of the 

problem areas identified at the monitored sites versus overall problem 

areas from total installer experiences. The second section of Data Fonn B 

was designed to gather additional information on failure modes and the 

time span associated with problem occurrences. Also, installers were 

requested to provi de comments concerni ng R&M experi ences wi th specifi c 

system components. 

Appendix B of this report presents additional results from the 

instal1er1s survey forms . It is extremely interesting to compare the 

resul ts from the fi el d test survey wi th the resul ts from the survey on 

overall installer field experience. The conclusions derived from the 

surveys appear s imil ar and one offers· verifi cati on as to the accuracy of 

the other. 

Survey Responses 

As mentioned, the survey forms were distributed to the two groups of 

program participants: installers and homeowners. ESG distributed the 

fonns to both participant groups in order to maximize the possibility of 

receiving at least one response on each monitored site from one or the 

other group. Table 1 shows the locations of the homeowner participants 

and the correspond; n9 number of responses and percentage of compl eted 

survey forms returned to ESG. Tabl e 1 al so shows the install er 1 ocati ons 

and the corresponding number of responses. 

Ouri ng the system performance moni tori ng phase of the test program 

over 1 60 solar water heaters were instrumented for data collection at onn 

time or another. The numb.er of homeowner participants avail able during 

the period the survey was conducted was 1 43. Some of the major reasons 

for the reduced number were as follows: 

4 
1 ) Homeowner moved 

2) Homeowner deceased 

3) Homeowner's lack of participation 

ESG distributed a total of thirty-six survey forms to the installer 

participants . The response rate of the survey for the installers (33%) 

was significantly lower than the homeowner response rate (73%). Again, 

the reasons for this situation were varied . However, the two major 

reasons were: 

1) Installer out of business 

2) Installer didn't have time to participate 

Numerous attempts were made to increase the program participant 

response rate . These efforts i ncl uded personal telephone contacts and 

follow-up letter correspondence . The majority of the initial 

non-responses were sent the survey forms again . 

ESG combined the homeowner and installer responses to identify the 

total number of system locations where at least one detailed survey form 

response was received . Table 1 provides information on the number of 

. respondents and thei r 1 ocati ons . A si gnifi cant response rate (85%) was 

recorded. 

It was encouragi ng to note the 1 evel of detail and the amounts of 

verifiable information gathered during the survey . The level of knowledge 

displayed by the individual homeowners was particularly noteworthy . Thus, 

a high level of confidence exists on the validity of the data . By design, 

there were numerous situations where both the homeowner and installer 

responded for the same system problem . In an overwhelming majority of 

these cases, the homeowner and installer responses were identical and 

identification of the problem area, the cause of the system problem, the 

required maintenance, and the costs associated for repairs were verified . 

5 
III . CATEGORIES FOR DATA RED UCTION AND ANALYSIS 

Initial Discussion 

The remaining sections of this report are primarily concerned with 

the presentation of the data and major findings derived from the survey . 

A majority of the information is presented in tabulation format to allow 

the reader easy reference . Findings of major importance or significance 

are addressed in the text . 

Categories of System Problem Areas 

Of the 1 4 3 solar water heater sites available for data gathering 

duri ng the survey, i nformati on was gathered on 1 22 systems or 85% of 

total. A breakdown of the system types and locations is given on 

Table 2. There were a total of 83 solar-related problem areas identified 

during the survey . These problem areas occurred on 57 of the 1 22 solar 

water heater systems which is 47% of the total sample . 

As shown in Table 2, five solar water heater system designs are 

listed. The system types are categorized in terms associated with freeze 

protecti on. II Reci rcul ati onll refers to system desi gn types whi ch prevent 

freeze damage by recirculating heated water from the storage tank through 

the exposed pi pi ng network when freezi ng condi ti ons exi st . "Drai nback II 

are the systems designed to prevent freeze damage by draining the water in 

the pi pi ng network to a reservoi r tank whenever the ci rcul ati ng pump is 

shut off. "Closed Loop" are the system types which have a glycol based 

ant i freeze so 1 ut i on added to the water in the pi pi ng network to prevent 

freezing. The closed loop systems also include systems which utilize 

silicone oils as the collector-to-storage heat transfer fluid. "Draindown" 

refers to system types which util ize an automatic draindown valve which is 

activated during freezing conditions. This valve allows water to drain 

from exposed piping and discharge from the system by gravity flow. The 

final system type listed in Table 2 is the manual freeze system type. This 

design type represents the systems which require "manual" operation of a 

valve in order to drain water from exposed piping when freezing conditions 

are anticipated. 

6 
In orde r to u nderstand the vari ous area s of system operati onal 

probl ems , the s urvey R&M data were categori zed accord i ng to frequency of 

occurrence . The reported system probl em areas were di vi ded i nto two kinds 

of probl ems . Type I probl em areas were cons; dered maj or probl em areas and 

were further defi ned a s : 1) any probl em resul ti ng i n a maj or system 

component re pl acement s uch as control l ers , pumps , draindown val ves , etc . , 

2) a ny probl em resul ti ng in out-of-pocket money in excess of $ 50.00 for 

the h omeowner, or 3) a ny probl em resul ti ng in freeze damage. The 

i mportant consi derati on in separati ng system probl em a reas i nto Type I or 

Type II was whether a probl em a rea represented a potenti al for si gn i fi cant 

cost to the homeowner . Type II probl em areas were defi ned as a ny "other " 

re ported probl ems n ot i nc l uded as Type I probl em areas . Two frequent 

kinds of Type II probl em areas were seY'vi ce cal ls to repai r a l eaki ng 

fi tti ng a nd repl acement of mi nor system components such as ai r vents or 

PIT val ves. There were a total of th i rty-two Type I and fi fty-one Type II 

probl em areas. 

Tabl e 3 d i splays the breakdown of the se probl em areas. A very 

i mportant i tem gi ven in Tabl e 3 is the row l abel ed IIn umber of probl ems per 

re porti ng sys tem ." These val ues a re c al cul ated by dividi ng the number of 

reported probl em areas for a given system des i gn type by the r . .Imber of 

re porti ng systems for the same type . Fo r i nstance , the recircul ati on type 

sys tem desi gn s reported a total of twenty -seven system prob1 em a reas. 

From Tabl e 2, the total number of reporti ng reci rc ul ati on systems is 

forty -six. Therefore , the total number of probl ems per reporti ng system 

for recircul a ti on type system is . 59. Tabl e 3 shows th is further d i vi ded 

i nto Type I and Type II probl ems (. 20 + .39). As noted , the reci rcul ati on 

sys tems experi e nced n i ne Type I probl em a reas and ei ghteen Type II 

probl ems wh i ch equal s twenty-seven tot31 probl em areas. The drai ndown 

sys tems h ave a total val ue of 1.50 (.83 + .67) wh i ch is rel ati vely high in 

compari son to other system types. ( NOTE: Because of the rel ati vely l arge 

n umber of probl em a reas with drai ndown sys tems , data in the remaining 

secti ons of th is report is someti mes presented wi th the drai ndown systems 

separated from the total popul ati on . ) 

7 
Referri ng to Tabl e 3, i n stal l ati on rel ated probl ems represented the 

category wi th the most frequent occurrences . Thi rty-six percent of a l l 

reported probl ems were in th is category. Instal l ati on rel ated probl ems 

i ncl uded n ot only the actual workmansh i p at the i nstal l ati on but al so 

probl ems as soc i ated wi th materi al and component spec i ficati on and system 

desi gn . It is bel i eved th at a majori ty of ttie reported system probl ems 

cou1 d have been total ly avoi ded if the system i nstall er and/or desi gner 

had b een more "careful " wi th system i nstal l ati on or better i nformed on 

materi al properti es and proper appl i cati ons . 

For exampl e, one i ns tal l er u tili zed a polybutyl ene pi pi ng sys tem on 

the col l ector supply and return l i nes for al l fi ve cf hi s mon i tored 

systems . The pi pi ng was not properly supported and hi gher than normal 

operati onal temperatures caused the pi pi ng to deform at the unsuppo rted 

sections . Th is resul ted in water remai ning in the col l ector pipi ng 

network duri ng freezi ng condi ti ons. One -by -one the pi pi ng systems fa iled 

and were repl aced . On e c oul d c onc l ude that pl asti C pi pe shoul d not be 

speci fied where potenti ally high temperatures are l i kel y , such as on the 

col l ector pi pi ng system . Th i s probl em was wi thout questi on , an 

i nstal l ati on related probl em because the materi al spec i fi ed probably 

s houl d not h ave been i nstal l ed. 

The next s ; ng1 e mos t frequent probl ern area wa s concerned wi th the 

di fferenti al temperature control l ers . One of the maj or repo rted causes of 

c ontrol l er fai l ures was due to l i gh tni ng . Many of the control l ers 

utilized had no i nternal circui t protec tion a gai nst h i gh surges caused by 

a nearby l i gh tni ng strike . ( ESG is only reporti ng the cause of the 

fai l ure i ndi ctated in the survey foms by the parti ci pants. It coul d very 

wel l be true that control l er fail ures a re only bel i eved to be caused by 

el ectrical stoms . In any case , it is obvi ous that al l con trol l ers shoul d 

be protected from external power s urges .) 

Drai ndown systems were pl agued wi th a greater than average n umber of 

system probl ems . The dra;ndown val ves utili zed wi th these system types 

caused a wi de assortment of operati onal probl ems . The val ve fai l ure s were 

8 
preval ent to the degree that thi s probl em area warranted a separate system 

probl em cate gory. Fi el d responses from i nstal l ers i ndicate that there is 

littl e con fi dence in the conti nuous, troub l e -free o perati on of thi s 

val ve . As i ndicated in the survey data gathered, dra i ndown probl em 

systems were 33% of the total number of problem systems while onl y 15% of 

the total number of reporti ng systems . 

Referri ng a gai n to Tabl e 3, another probl em category wi th a 

s i gn i fi cant n umber of occurrences was the category l abel ed lI other.1I This 

category wa s desi 9nated to i ncl ude probl em a reas of either l ower frequency 

of o ccurrence or problem a reas cons i dered to be l ower in i mportance . The 

fol l owi ng is a l i sti ng of the types of probl em areas i ncl uded in the 

"o ther" cate gory. 

1 - Pressure/temperature val ve l eak i ng 

2. Check val ve fau l ty 

3. Ai r vent mal functi oni ng 

4. Val ve seal l eak i ng 

5. Gl ycol added 

6. Leak at si ght gl ass 

7. Drai nback reservoi r tank 1 eaking 

The probl em category i'l Tabl e 3 l i s ted as "corrosi onll refers to 

probl ems whi ch devel oped d ue to sedi ment bui l dup in tanks or in the pi pi ng 

network . Corrosi on wa s the onl y probl em area whi ch was determi ned to be 

geographical ly excl usi ve . Al l of the corrosi on rel ated probl ems were 

experi enced by systems l ocated in the Jacksonvi lle, Fl ori da area . 

IIGl azi n gll refers to probl ems rel ated to the gl ass or pl astic covers 

for the co 11 ector panel s. There were three i ns tances of gl azi n9 

probl ems . Two of these were due to the fadi ng of the polyester fi bergl ass 

mate ri al utili zed as gl azi ng. There was only one i nstance of gl ass 

breakage out of an approximate total of over 200 col l ectors operati ng for 

an average of 2.5 years. 

9 
IV. EFFECTS OF PROBLEMS ON HOMEOWNER 

On e of the most one-s i ded responses from the homeowner survey was 

concerned wi th atti tude . ESG asked the i ndi vi dual homeowners whether or not 

they were "gl ad " they purch ased a sol ar water heater . An overwhel mi ng 92% of 

the homeowners responded "yes II wi th the maj or reason bei ng "dol l ar sav; ngs . 

II 

The second most recorded reason for l i k i ng thei r sol ar water heater purchase 

was due to the 1 a rge amounts of hot water ava i l abl e. It was somewhat 

s urpri si ng to discover h omeowners wi th rel ati vely l ow performi ng sys tems 

remaini ng pleased wi th thei r sol ar sys tem purchase . In the majori ty of the 

"yes" responses , th e homeowners were enthusi asti c in thei r expres sion of 

posi ti ve opi nions toward sol ar energy. 

Of th e 83 system probl em areas i denti fied in the survey , twel ve resul ted 

in out-of-pocket expendi tures for ten homeowners. The average cost per probl em 

to the homeowner was $105.00. As it was, al l but one of the homeowners remai ned 

"gl ad" they purchased thei r system. The onl y homeowner in thi s group who was 

di s sati sfied with the purchase spent a total of $674 in repairs. Without 

, i ncl uding thi s parti cul ar homeowner, the average cost per reported probl em to 

the homeowner was $78. 

The ten systems i denti fied above were in operation for an average of 3.3 

years . The fol l owi ng is a lis t of the probl em areas whi ch resul ted in a cost 

to the homeowner . 

Probl em Area Average Co st # of Occurrences 

Con trol l er repl aced $ 65 3 

Pump repl aced 244 3 

Sensor repl aced 48 1 

Ai r vent repl aced 20 1 

Gl azi ng repl aced 30 1 

Gl ycol added 74 1 

Pump seal s repl aced 99 1 

Freeze damage repai red 1 75 1 

10 
v. REPORTED CAUSES OF SYSTEM PROBL EM AREAS 

Ini ti al Di scussi on 

In th is s ec ti on of the report the causes of the maj or probl em rel ated 

categori es , l i s ted in previ ous secti on s, a re addressed . In many cases , 

there a re probl ems where the "actualll causes of the c omponent fa i l ures are 

unknown. For i nsta nce , when a control l er fai l ed, the specific cause of 

th e fai l ure may only be determi ned duri ng an ac tual physi cal i ns pecti on of 

the unit. Phys i cal component i nspec ti on is beyond the scope of th is work 

e ffort . Th erefore , data is presented as it wa s recei ved by ESG , and 

component fa i l u re can onl y be di scussed in terms of the frequency of 

occurrence in most i nstances . 

Instal l ati on Rel ated Probl ems 

Of the 83 reported system probl ems , 30 a re rel ated to i ns tal l ati on . 

The i nstal l ati on rel ated probl em category i ncludes the areas of actual 

o n-s i te workmanshi p, materi al and equi pment specifi cati ons, and system 

desi gn. If a probl em is a d i rect resul t of i nadequac i es in any of these 

areas , it is desi gnated as an i nstal l ati on or i nstal ler rel ated probl em . 

Actual on-si te workmanshi p probl ems accounted for 16 of the 30 

i nstal l ati on rel ated probl ems . Th e fol l owi ng is a l i sti ng of the reported 

workmanship probl ems. 

Workmanship Probl ems 

1) Sensor l ocated in wrong pl ace 

2) Pi pes not properly sl oped 

3) Leak s where pipes enter roof 

4) Leak at p i pe fi tti ngs 

5) Col l ector supply and return 

p i pi ng reversed 

6) Solder in p i pe 

11 

# of Occurrences 

5 

4 

3 

2 

1 

1 
Materi al and equi pment speci fi cati ons are of maj or i mportance to the 

tro ubl efree o perati on of sol ar water heaters . At times , i nstal l ers may 

attempt to "cut corners" and i nstal l equi pment and utilize materi al s that 

are not desi gned for the a ppl i cati on . One maj or area of i mproper materi al 

spec i fi cati on is roo f pi pi ng i nsul ati on. At this stage of i ndus try 

devel opment, it is conunon k nowl edge that el astomeri c i nsul ati on systems 

requ i re protecti on from ul traviol et de gradati on. However, four i ns ta nces 

were recorded where the pi pes were n ot properly protected and shri nkage 

and ul timate fai l ure of the i nsul ati on system occurred . 

Eq ual ly apparent in the probl em area of materi al spec; fi cati ons is 

the mi suse of pl asti cs in sol ar systems . There is wi thout questi on a 

n umber of pl asti c resin systems wh i ch are desi gned to mai ntain thermal and 

mechani cal properti es for sol ar system appl i cati ons . In two separate 

c ases , h owever , i nstal l ers sel ec ted the wrong appl i cati on for pl astics 

wh i ch resul ted in si x systems reporti ng probl ems . The two cases i nvol ved 

th e u se of pl asti c tubi ng for sight gl asses a nd the second , and much more 

consequenti al , wa s the use of pol ybutyl ene pi pi ng as the col l ector suppl y 

a nd re turn 1 i nes . As was previously di scu s sed , polybutyl ene wi ll not 

mai ntai n mechani cal properti es above 2300F and shoul d not be uti l i zed 

where there is a potenti al for these temperatures . 

The l ast a rea where materi al and equ i pment speci fi cati ons were 

i nadequate is concerned with pump spec i fi cati ons . Two cases were reported 

where cast i ron bodi ed circul ati ng pumps were utili zed in open or vented 

systems . Th ese situati ons re sul ted in eventual repl acement of both pumps , 

where one pump actual ly became corroded to the poi nt where it sei zed u p . 

The l ast probl em area in the i nstal l ati on rel ated probl em category 

deal s wi th system desi gn . Th is area seems to be of only mi nor 

sign i fi cance to o perati onal downti mes . Two i nstances were reported where 

check valves were omi tted from the ori gi nal system desi gn resul ti ng in an 

excessive heat l oss due to thennosi phoni ng from the storage tank. These 

situati ons coul d well be considered a workmanshi p probl em area, however, 

there were i ndi c ati ons with one of the systems that thi s situation was a 

system desi gn rel ated probl em area. 

12 
It is di ffi cul t wi th this type of data col l ecti on to i denti fy other 

system desi gn probl ems , especi al ly those rel ati ng to l ow system 

performance effici enci es. As previ ously menti oned , the fiel d test pro gram 

was desi gned to gather performance data a nd therefore performance 

hi stori es do exi st. Howeve r , the re woul d be a need to gather data by site 

visi ts on the l ower performi ng systems in order to accurately i denti fy l ow 

performers whi ch resul t from poor system desi gn. 

Co ntrol l er Re l ated Probl ems 

There were el even control l er fai l ures reported duri ng the survey of 

the 1 22 sol ar water heaters. The actual and speci fi c causes of the 

fai l u res of di fferenti al temperatu re control l ers are_ unk nown . As 

menti oned , in o rder to dete rmi ne actual cause , the con trol l ers woul d have 

to have been phy si cal ly i n spected . Si nce thi s was not a part of the 

proj ect I s scope of work , it was not done and the reports on the causes 

must be taken at face val ue . Undoubtedly, the maj ori ty of the fai l ed 

control l ers were returned to the manufacturer for i nspecti on . 

Se nsor Rel ated Probl ems 

Two of the most frequent means that a homeowner i denti fi es a sys tem 

probl em area a re when he/she noti ces the pump runni ng at ni ght or not 

runn i ng duri ng sunny days . Us ual ly when these symptoms are noticed , the 

con trol 1 er or one of the control sensors is at faul t. Sensor rel ated 

probl ems accounted for 1 0% of the total number of reported system probl ems 

and al l of these probl ems were detected by one or the other symptom . 

Every sensor probl em reported was remedi ed by re pl acement of at l east one 

control sensor. 

As with the control l er rel ated probl ems , it is d i fficul t to determi ne 

"actua l" cause of sensor fa i l ure . A sensor fai l ure du ri ng freezi ng 

condi ti ons can be extremely costly for drai ndown and reci rcul ati on type 

systems. It i s obvi ous that homeowners shoul d mai ntai n a "watchful eye" 

on their system in order to quickly detect sensor mal functi on . 

13 
VI. OPERAT IONAL T IME WHE N PROBL EMS OCCURRED 

System Operati ona.l Peri ods 

Informati on was gathered concerni ng the time when probl ems occurred 

in rel ati on to the i nstal l ati on date. Table 4 and Tabl e 5 show the 

n umbers of probl ems whi ch occurred over time fol l owi ng the ori gi nal 

i nstal l ati on date . The data are accumul ated in ti me b l ocks of s i x mcnth s 

durati on . Th is presentati on of data permi ts the compari sons over a time 

frame up to 30 month s, or greater . 

The majori ty of th e data were gathered duri ng the fi rst and second 

year of operati on ; however , there were a number of systems where R&M data 

were gathered duri ng the th i rd, fourth , and greater years of operati on . 

In order to emphasi ze the si gni fi cance of the n umerou s probl ems 

experi enced by the draindown type systems , tt �se system types were 

separated from the total popul ati on in Tabl e 4. As di scussed in an 

earl i er secti on , the probl em areas were al so d i vi ded i nto Type I and Type 

II probl ems in Tabl e 4 and Tab le 5. 

As shown in Tabl e 4, a n umber of i nteresti ng observati ons can be 

made. . The important val ues to note are the val ues in the rows desi gnated 

as lithe n umber of probl em areas per system II shown in Tabl e 4. These 

val ues equate the rel ati ve number of probl ems to the number of systems 

re porti ng duri ng the speci fic peri ods of system operati on . Tne number of 

report; ng systems decreases greatl y after the 24th mon th of operati on , 

therefore , d ata presented after th at time is of l ess s i gni fi cance . The 

drai ndown type systems do not have any operati onal hi stori es after the 

second year . Fi gure 1 depi cts the data gi ven in Tabl e 4 wi th the Type I 

and Type II probl ems total ed . 

Tabl e 4 shows that the rec i rcul ati on , drai nback , 

manual freeze type systen 5 appear to experi ence Type 

d uri ng earl y system o perati on . These sys tem types 

c l osed l oop , and 

II probl em a reas 

al so appear to 

experi ence an i ncreasi ng number of Type I probl em area s in rel ati on to the 

14 
number of reporti ng systems duri ng l ater operati onal peri od s. Conversely, 

the drai ndown type systems experi enced Type I probl ems in rel atively 

s i gni ficant n umbers duri ng early operati onal peri ods. Data is not 

a vai l abl e for o perati onal peri ods beyond two years for dra i ndown systems. 

Tabl e 5 shows the operati onal time peri ods· when parti cul ar categori es 

of probl ems occur. The probl em categori es a re divi ded i nto two groups . 

Group A i ncl udes the reci rcul ati on, drai nback, cl osed l oop, and manual 

freeze system types . Group B i ncl udes the drai ndown systems only. 

Referri ng to Tabl e 5, it appears that a majori ty of these Type II probl em 

a reas a re concerned with i nstal l ati on rel a ted prob1 ems and mi nor system 

component fai l ures such as PIT val ves and a i r vents . As the system 

o perati onal time i ncreases beyond two years, Type II probl ems decrease 

accordi ngly and the more seri ous Type I probl ems begi n to i ncrease in 

n umber per reporting system . The maj ori ty of control l er and pump fa i l ures 

occur a fter the fi rst year of system operati o n . The drai ndown systems 

e xperi enced fai l ures of the val ves earl y in system l i fe for a s peci fi c 

reason. These draindown val ve fai l ures u sual ly occurred duri ng the fi rst 

wi nter season , whi ch was u sual ly in the fi rst six months of operati on . 

Seasonal Vari ati ons 

Thi s secti on of the report is concerned wi th examl nl ng seasonal 

rel ationsh i ps between sys tem types and probl em area s. The 83 reported 

system probl em a reas were tabul ated by the season of the year in whi ch 

they occurred . Tabl e 6 and Fi gure 2 show the seasonal vari ati ons in the 

n umber of probl em areas according to the va ri ous system types . Tabl e 6 

presents the data by Type I and Type II probl ems as di scussed earl ier. 

Fi gure 2 shows the combi ned total s. Tabl e 7 di spl ays the i ndivi dual 

probl em area categori es and the correspondi ng number of probl ems on a 

seasonal basis. 

Accordi ng to Tabl e 6, the drai nback and cl osed l oop type systems seem 

to have their greatest number of probl ems in the summer season whi le th.e 

reci rcul ati on a nd drai ndown type system have the i r greatest number of 

operati onal probl ems in the winter season . It is i nteresti ng to note that 

the spri ng season displ ays the fewest n umber of system probl em a reas . 

15 
A greater number of the total problem areas occur during the winter 

season. One reason for thi s situati on is due to the col der and, at times, 

freezing temperatures experienced by solar water heaters during this 

season ; nine systems recorded freeze damage. Installation related problem 

areas, such as the piping system installation, most readily became a Type 

I problem duri ng the wi nter season due to freeze damage . As shown in 

Table 7, every problem area had the greatest number of occurrences in the 

winter season except the sensor related problems . Sensor related problems 

seemed to be most frequent duri ng summer and spri ng seasons . Other data 

show that the higher than normal operating temperatures in the collector 

subsystems in the summer months appear to cause a higher rate of sensor 

fail ures . 

VII. CONCLUS IONS 

Overall, the survey was considered particularly useful since it provided 

some of the first data on a reasonable number of state-of-the-art systems over 

a time period which exceeded 24 months . The data is presented in a manner 

whi ch may be hel pful in determi ni n9 the areas where conti nui ng indust ry and 

government research efforts may be helpful . Some of the key observati ons 

which may be made are as follows: 

1. Of the 1 22 solar water heater systems which provided reliability and 

maintainability data, 57 systems reported at least one problem area . 

This results in an impressive 65 solar water heater systems which 

operated without any R&M problems for a period of approximately two 

years . 

2. The flat plate collector and storage subsystems are highly reliable 

parts of residential solar water heater systems . 

3. Installation related problems are the most frequent cause of improper 

system operation. In all probability, this type of problem should 

decrease as existing installers learn from their mistakes and new 

i nsta 11 ers, hopefully, wi 11 also benefi t from the grow; ng base of 

experience. 

16 
4. Drai ndown type sol ar water heaters i nstal l ed in the program from mi d 

1 981 to early 1 982 experi enced a rel ati vely h i gh number of 

operati on al probl ems wi th fai l u re of the drai ndown val ve as the most 

preval ent cause . Approximately 9 out of 10 dra i ndown systems appear 

to have Type I system operati onal probl ems. 

5. The maj ori ty of system probl ems occur duri ng the wi nter season. 

6. The di fferenti al temperatu re control l ers were responsibl e for the 

greatest number of Type I probl em area s. Nearby l i ghtni ng stri kes 

appear to be a signi ficant cause of control l er fai l u re . Type I 

probl em a reas are defi ned as a probl em area : ( l ) requl rlng a maj or 

system component repl acement , (2) resul ti ng in out of pocket money 

from the homeowner in excess of $50 .00, or (3) re sul ti ng in freeze 

damage . 

7. .There is actua l ly only a sl i ght di fference in the total number of 

probl ems between the fi rst year and second yea r of system operati on 

when the dra i ndown systems are not i nc l uded in the te st popul ati on. 

Type II p robl em a reas a re more frequent duri ng early system operati on. 

8. The dra i nback type sol ar water heater is the l east l i kely system type 

to have a Type I probl em. 

9. An overwhel mi ng maj ori ty of homeowners are " gl ad" they purchased a 

sol ar water heater even though a number of system p robl ems were 

experi enc ed . 

17 
# of # of 

Queried Responding Queried Responding Installer Homeowner or 

Location Homeowners Homeowners Installers Installers S�stems Installer S�stems % Return 

1. Florida 84 62 20 8 38 72 86% 

2. North Ca ro 1 i na 9 7 3 0 0 7 78% 

3. Virginia 14 6 3 2 9 12 86% 

4. Georgia 7 6 2 1 4 7 10()'f, 

.. 

(X) 

5. South Carolina 5 5 1 0 0 5 10()'f, I j 

6. Alabama 14 12 3 1 8 13 93% .1 

7. Texas 9 5 3 0 0 5 56% 

i8. Kentucky 1 1 1 0 0 1 10()'f, 

, 

TOTALS 143 104 36 12 59 122 85% 

TABLE I. NUMBER AND LOCATIONS OF RESPONDING PROGRAM PARTICIPANTS 
..... 

1.0 

SYSTEM TYPES 

STATES 

Cl osed Manual 

Recir. Drai ndown Dra i nback Loop Freeze Totals 

1. F l ori da 44 10 13 1 '4 72 

2. North Ca rol i na 0 0 0 7 0 7 

, 

3. Vi rgi nia 0 3 0 9 0 12 

4. Georgia 0 2 1 4 0 7 

5. South Ca rol i na 2 0 0 3 0 5 

6. Al abama 0 0 9 4 0 13 

7. Texas 0 3 1 1 0 5 

8. Kentucky 0 0 0 1 0 1 

�---

Tota l s 46 18 24 30 4 122 

------ ----- ------- --�--�-.--.----.. - _ .. -- --

_ .. _-- - --- --

-- --- ------

TABLE 2. LOCATIONS OF REPORTING SYSTEMS ACCORDING TO SYSTEM TYPE 
N 

o 

PROBLEM CATEGORY 

Installation 

Controllers 

Pumps 

Sensors 

Draindown Valves 

Corrosion 

Glazing 

Other 

Total 

'1, of Total 

If of Problems3 

per Reporting 

System 

----

-----

Recirculation 

11 I I2 

3 4 

3 

2 

1 3 

N/A N/A 

3 

2 

6 

9 18 

33% 

.20 . 39 

-- -----

Draindown 

I II 

2 7 

5 

1 

1 

7 

1 

3 

15 12 

33% 

.83 .67 

SYSTEM TYPE 

Drainback 

I II 

1 6 

1 

N/A N/A 

1 

4 

2 11 

16% 

• Oil .46 

Closed Loop Manua 1 Freeze Totals � of Total 

I I I I II I II I & II/Total 

2 5 8 22 36'1; 

2 1 11 13� 

4 5� 

3 1 7 10'& 

.-. 

N/A tl/A N/A N/A 7 m 

4 5� 

3 U 

1 2 1 15 19\ 

5 10 1 32 51 --

18% 1% -- 1O<n 

.17 .33 .25 0 .26 . 42 --

Notes : l)Denotes Type I probl em area s as defined as any problem resul ting in any one of the fo l l owing : (a)repl acement of major sys tem component; (b)out of pocket cost to homeowner in exces s of $50; or (c)freeze damage . 

2)Denotes Type II pro bl em area s as defined as any probl em not designated as Type I pro bl em . 

3)See explanation in text . 

TABLE 3. NUMBER OF PROBLEM AREAS FOR SYSTEM TYPES ACCORDING TO PROBLEM CATEGORIES 
MONTHS OF OPERATION 

0-6 7-12 13-18 19-24 25-30 31 .. TOTAlS 

SYSTEM 

TYPE 

11 1I2 I II I II 

Reci rcul ation 1 4 1 3 2 3 

prai nback 1 6 1 2 

losed Loop . 4 2 5 

�anua 1 Freeze 

�ubtotals 2 14 1 4 4 10 

If of Systems 49 76 77 

II of Problems 

Per System .04 .29 .01 .05 . 05 .13 

praindown 9 3 2 6 3 3 

# Draindown 

Systems 12 16 16 

# of Problems 

Per DO System .75 .25 .13 .38 .19 .19 

Total # of 

Prob 1 ems 11 17 3 10 7 13 

1# of Reporting 

f:>ystems 61 . 92 93 

�ota1 # of 

Prob 1 ems Per .18 .28 .03 .11 .08 .14 

�ystem 

NOTES: 1) See Note 1, Tabl e 3 

2) See Note 2, Table 3 

I II I II I II I 

1 2 3 4 3 9 

1 1 1 2 

1 1 2 5 

1 1 

1 4 2 4 7 3 17 

68 28 26 

.01 .06 .07 .14 .27 .12 

1 15 

13 2 

.08 I 

2 4 2 4 7 3 32 

i 

81 I 30 26 

.02 .05 .07 .13 .27 .12 

TABLE 4. NUMBER OF PROBLEM AREAS FOR SYSTEM OPERATIONAL 

TIMES ACCORDING TO SYSTEM TYPE 

21 

II 

18 

11 

10 

39 

12 

51 
MONTHS OF OPERATION 

0-6 7-12 13-18 19-24 25-30 31. TOTALS 

PROBLEM 

CATEGORY GROUP 

1

1 Il2 1 

A3 2 7 

INSTALLATION 

84 1 3 

A 

CONTROLLER 

B 3 1 

A 1 

PUMP 

B 

A 2 

SENSORS 

B 

A 

DRAINDOWN 

VALVES 

B 5 1 

A 

CORROSION 

B 

A 1 

GLAZING 

B 

A 4 

OTHER 

B 

A 2 14 1 

TOTALS 

8 9 3 2 

Notes : I ) See Note 1, Table 3. 

2 ) See Note 2, Table 3. 

II 1 II I II I II I II I 

2 1 4 2 1 2 6 

2 1 2 2 

2 4 6 

1 5 

1 1 3 

1 1 

1 3 1 1 

1 

1 7 

1 3 

1 

1 

1 3 1 1 1 2 1 

2 1 

4 4 10 1 4 2 4 7 3 17 

6 3 3 1 15 

3 ) Group A includes recirc ulation, drainback, clo sed loop, .and 

manual freeze sys tem types. 

4 ) Group B includes draindown systems only . 

TABLE 5. NUMBER OF PROBLEM AREAS FOR SYSTEM OPERATIONAL 

TIMES ACCORDING TO PROBLEM CATEGORIES 

22 

II 

15 

7 

6 

1 

4 

2 

1 

12 

3 

39 

12 
I'\) 

w 

SPRING 

1

1 I l

2 

Red rcu1 ati on 2 4 

Draindown - 4 

Drainback - -

Closed Lo op 1 3 

Manua 1 Freeze - -

Total s 3 11 

'1 of Total s 9% 22'1 

Notes: l)See Note 1, Tabl e 3. 

2)See Note 2, Tabl e 3. 

SUMMER 

I II 

1 4 

2 1 

1 5 

1 4 

- -

5 14 

1 6% 27% 

FALL W I NTER TOTALS 

I II I II I II 

2 5 4 5 9 18 

3 1 10 6 15 12 

- 4 1 2 2 11 

2 1 1 2 5 10 

- - 1 - 1 -

7 11 17 15 32 51 

2 2'1 2 2'1 5 3'1 29'1 - -

TABLE 6. SEASONAL VARIATIONS IN NUMBER OF PROBLEM AREAS 

ACCORDING TO SYSTEM TYPE 
I'\) 

� 

! 

PROBLEM AREA SPR I NG SUMMER FALL WINTER TOTALS 

Instal l ation .. 5?(]7%)* 

.:'�;,::" . 

8 (27%) 7 (23%) 

Control l er 2 (1 8%) 2 (1 8%) 3 (27%) 

Pump 1 (25%) 1 (25%) 1 (25%) 

Sensor 3 (38%) 3 (38%) 1 ( 1 3%) 

Dra i ndown Va l ves o (0%) o (0%) 1 (1 4%) 

Corrosion o (0%) o (0%) 2 (50%) 

Gl azi ng o (0%) o (0%) 1 (33%) 

Other 3 (1 9%) 4 (25%) 3 (1 9%) 

TOTALS 14 (1 7%) 19 (23%) 18 (22%) 

--_._- -_._. --

---.-.----

* � % of Total 

.. 

-" .. � . 

10 (33%) 

4 (36%) 

1 (25%) 

1 (1 3%) 

6 (86%) 

2 (50%) 

2 (67%) 

6 ( 58%) 

32 (39%) 

30 

11 

4 

8 

7 

4 

3 

16 

83 

TABLE 7, SEASONAL VARIATIONS IN NUMBER OF PROBLEM AREAS 

ACCORDING TO PROBLEM CATEGORY 

._-

! 
I'\) 

0'1 

IHIR. 

1 

OOIItiACK 

r7111 

Q.OSED UJF 

� 

OOIIOlIIN 

-

1.1 

1.8 

8.9 

8.8 

8.7 

8.6 

8.5 

8.4 

8.3 

8.2 

8.1 

8.B 

PR(B..EMS/R£roUlt«; SYSTEMS 

BT06 7 TO 12 13 TO 18 19 TO 24 

IOfTH5 IF lFERA TI� 

Notes: l)See expl anation in text concerning reduced number of working 

draindown systems. 

2)See discussion in text concerning number of probl em areas 

after two years of operation, see al so Tabl e 5. 

FIGURE 1. PROBLEMS PER REPORTING SYSTEMS FOR VARIOUS 

SYSTEM TYPES OVER TIME 
N 

0'1 

NUMBER OF PROBlEM. AREAS 

18 

RECIRC. � 

16 

14 

mAINDOWN 

12 rlill 

mAINBAO< 1S 

f\2YYj 8 

a.OSED LOOP 6 f7II7m 4 

MAN. FREEZE 

2 

B 

SPRING SUMMER FALL WINTER 

SEASONS 

FIGURE 2. SEASONAL VARIATION IN NUMBER OF PROBLEM AREAS ACCORDING TO 

SYSTEM TYPE 
APPEND IX A 

PROGRAM PART I C I PANTS SU RVEY FORM S PACKAG E : 

- Excerpt from Lette r to Al l Homeowners 

- Da ta Form A ( Homeowner ) 

� Data Form B ( Homeowne r) 

- Excerp t from Le tter to Al l Insta l l ers 

- Data Form A ( Instal l e r) 

- Da ta Form B ( Instal l er) 

A-l 
Si te Code --'-

Exce rpt from Letter to Al l Homeowners: 

We woul d 1 i ke to now ask you and your fami ly for an additi onal e ffort in 

providi ng us i n fonnatio n concerni ng the rel iabi lity and user experi e nces you 

have had wi th your moni tored system . At the same time, we wil l send a l etter 

to your system i nstal l er for addi ti onal i nfonnation on his sol ar systems being 

moni tored under the program , i ncl uding your system . 

We woul d greatl y apprec i ate your ai d in compl eti ng two types of data fonns 

whi ch a re encl osed . The II All Da ta Form is direc tl y concerned wi th the speci fic 

probl em areas your system has experi enced in the monitori ng program . Our 

objec ti ve is to col l ect data on each of the probl ems wh i ch were encountered . 

Thi s wi ll be useful in gui di ng future research pro grams. I might hasten to 

add. we do see the overa 11 performance of the moni tored systems as quite 

good . Hope ful ly, your i nputs wi ll hel p mak e even better components avai l abl e 

in the future . 

A package of the II All Da ta Forms is e ncl osed a l ong wi th your 1 atest Monthly 

Summary Report . We ask that you compl ete a separate IIA" Data Form for each 

probl em noted on the summary . We have noted wi th a red l i ne each instance 

where there appeared to be a probl em . Al so , if you k now of other probl ems 

wh i ch a re n ot l i sted on the performance summary , pl ease compl ete an addi ti onal 

questi onnam on each such probl em . Fortunatel y, there a re not too many of 

these events so your job shoul d not be di ffi cul t. We do recogni ze th at you 

wi ll have to II sea rch your memory" to provi de ful l detai l s. Pl ease do the best 

you can to recal l each event. If you think that I c an hel p by expl aining any 

of the coding on the perfonnance sheet , please c all. Encl osed with the IIAII 

data form is a re ference sheet enti tl ed II Exampl es of System Probl em Areas. 1I 

Pl ease revi ew th is sheet pri or to compl eti ng the forms in order to fami l i arize 

yoursel f wi th the probl em a reas of concern . 

After compl eti on of your group of IIAII Data Fonns , pl ease compl ete the 1

1

8 II 

Da ta Form whi ch provi des general i nformati on concerni ng the i mpac t of your 

system on your da ily l i vi ng patterns . We bel i eve that your experi ence is 

extremel y val uabl e for assess; ng the most i mportant areas concerni ng fi el d 

operati on and system rel i abili ty. As you k now , fiel d expe ri ence is where this 

type of data can best be gathered . Th is form is sel f-expl anatory and does not 

requi re any reference to the perfonnance mon i tori ng data . 

A -2 
The addi ti onal data to be furni shed by you and your family wi ll only be 

utili zed as part of the stati sti cal data . Your answers wi ll be i denti fied by 

your si te code number. The data gathered wi ll only be summarized and wi ll not 

be reported indi vi dual ly, or i denti fied , in any way to anyone . 

Let me know if you have any questi ons or comments concern i ng the program 

or th is addi ti onal effort . Encl osed is a prepaid e nvel ope for returni ng the 

compl eted forms. You r cooperati on and assi stance i� greatl y appreci ated . 

(Le tter c onti nues wi th cl osi ng statement and expression of thank s--si gned by 

W. M. Jones, ESG Program Manager .) 

Enc l osures : 

Data Form A 

Da ta Form B 

A-3 
DATA FORM A: REVIEW OF PROBLEMS WITH YOUR MON I TORED SYSTEM 

Introducti on 

Re fer to th e Monthly SUl'l1ary sheet on your mon i tored system wh i ch is 

prov i ded separately. On thi s sheet , any i denti fi ed probl em is marked wi th a 

red 1 i ne wh i ch usual ly k eys to the date of the occurrence . Uti l i ze the 

encl osed l i st enti tl ed " Exampl es of System Probl em Areas" as a reference. 

Pl ease compl ete a separate questi onna; re for each probl em usi n9 the date 

to di fferenti ate between two or more probl ems of you r system . If you know of 

a probl em not i denti fi ed on the Month ly Summary sheet, pl ease i dentify lt and 

use the approxi mate date . 

Tel ephone ESG , Inc . at (404) 457-8790 if you h ave any questions . Ask for 

Will iam M. Jones . 

Items as Foll ows : 

1. Homeowner Name 

Locati on (Ci ty and State) 

2. Si te Code ( from Mo nthly Summary Sheet ) 

3. Ap proxi mate Date of Probl em 

( from Summary Sheet or other sources) 

4. Descri be the probl em wi th your system , i . e . , what were the symptoms? 

5. How did you k now the problem existed? 

6. Descri be the correc ti ve mai ntenance performed on-si te. 

7. Name a ny system c omponents that were repl aced . 

A -4 
8. Indi cate th e cause of th e system or componen t probl em. 

9. What was the cost to you for repair or repl acement? 

10. Was th e repai r or repl acement cost covered under any warranty? 

11. Di d th e i ni ti al fa i l ure c ause other probl ems wi th th is system? 

If yes , pl ease descri be . 

1 2. Addi ti onal comments ( use e xtra sheet if necessary ). 

A-5 
EXAMPLES OF SYSTEM PROBL EM AREAS 

The fol l owi ng is a l i st of areas where you r system coul d have experi ence d 

probl ems . Pl ease revi ew th is l i st pri or to c ompl eti ng the data forms encl osed . 

A. Control l er: 

- Pump n ot running at a l l 

- Pump runn i ng at ni ght or when su n not avai l abl e 

- Pump runn ing at al l times 

- Improper cal i brati on ( reduce d effi c i ency eve n though system 

may operate ) 

B. Sensors : 

C. Tank.s : 

D. Pump : 

- De fecti ve sensor 

- Faul ty wi ri ng 

- Improper sensor pl acement 

- Leak. i ng tank (sol ar or c onventi onal ) 

- Corrosi on or sedimen t bu i l dup 

- El ectric el ement in tank burned out 

- Thermosta t setti ng i ndi cati ng wrong temperatu re 

- Pump fai l ure (col l ector l oop or h eat exchanger l oop ) 

- Pump Cavi tati ng (Ai rl ock ) 

Eo Col l ectors : 

- Condensati on on transparent cover 

- Leak i n g pi pe in col l ector 

- Broken gl ass c over 

- Faded gl ass or pl asti c cover 

- Col l ector support struc ture probl em 

F. Pi pi ng: 

- Leaking p i pe on roof 

- Leak i n g pi pe i n -house 

- Pi pi ng materi al deteri orated ( pl asti c pipe) 

- Pi pi ng i nsul ati on degraded on roo f ( shrunk or fel l off ) 

- Scal e or corrosi on b ui l dup in p i pes 

G. Freeze Damage: 

- Sa gging p i pes trapped water on roof ( i mproper drai nage ) 

- Control s fai l ed causi ng freeze damage 

- Dra i ndown val ve fa i l ure 

- Anti freeze sol uti on i neffecti ve 

H. Other System E1 ements : 

- Heat exch anger corrosi on or scal e b uildup 

- Leaki n g hea t exchanger 

- Drai ndown v al ve fai l ure 

- Drai ndown valv e 1 eak i ng (seal s) 

- Vacuum b reaker fai l ure 

- Ai r ven t fai l ure 

- Temperi ng val ve defecti ve 

- Pressure /temperature rel ief val ve fai l ure 

- Shadi ng probl ems 

- Water l eak at parti cular components or l ocati ons 

A-6 
DATA FORM B: USER I NFORMATION 

Homeowner Name Ci ty State 

Si te Co de 

In troducti on 

Th i s i s i ntended to draw on your experi ences as a homeowner wi th an 

i nstal l ed sol ar water heater in order to better u nderstand h ow your sys tem is 

performing a nd h ow you h ave b een usi ng the system . Pl ease be as i nformati ve 

as possi bl e in compl eti ng this form. 

Sec ti on 1 - General System Informati on 

1. Approximatel y when was your sol ar system i nstal l ed? 

2. Pl ease i ndicate the storage tank thermosta t setti ng and any seasona l 

changes you mi gh t make d uri ng the year. 

Tank Thermosta t Setti ngs 

Actual Tank Temperatu re (OF ) Setti ng 

or 

H i -Medi um- Low Setti ng 

Al l Year Wi nter Sununer 

3. How does your sol ar system 's tank thermostat setti ng compa re to your 

previ ous conventi onal tank thermosta t setti ng pri or to your sol ar system 

i nstal l ati on? (Check o ne) --

l owe r; h i gher; th e same . 

4. Pl ease check [ ] the a ppropri ate i tem concerni ng how your backup el ectri c 

el ement in you r tank is operated . 

--Power to e l ement on year round a nd . never ch anged . --Power to el emen t is cortrol l ed seasonal l y . 

Power to e l ement c ontroll ed by timer. -- Power to el emen t is control l ed manual ly and turned on whe n , 

-- no h ot water ; 

--before baths, c l othes washing, d i shwashing , etc . , onl y 

__ 

every so o ften, no parti cul ar time 

other, expl ai n 

5. Du ri ng the f i rst year of o perati on for your resi denti al sol ar hot water 

system , what was the number of fol l ow-u p service cal ls by the i nstal l er to 

your h ouse? __ _ 

6. Of these return visi ts by the i nstal l er, what is the n umber of ti mes when 

you bel i eved there was a probl em , but the i nstal l er expl a i ned that there 

actual ly was no probl em? --

A-7 
Sec t; on I I - General Informati on 

1. Pl ease check [ ] your typi ca 1 time of day hot water use. 

Morni ng Afternoon 

No Spec ; al 

Even i ng Time of Day 

- Cl othes Washing 

- Di shwash i ng 

- Shower/Baths 

2. Do you b el i eve you use th e most hot water duri ng the __ morni ng ; --afternoon ; evening. (Check one i tem ) 

3. Does your fami ly do the major hot water usages , such as cl othes wash i ngs , 

onl y on days when there was very good sunsh i ne? ( Yes or No ) __ _ 

4. Have you ch anged the time of day you use hot water as a resul t of your 

sol ar hot wate r system purchase? ( Yes or No ) Expl ai n bri efly. 

5. Are you gl ad you bough t a sol ar water h eater? 

Section III - Addi tiona l In formati on 

Pl ease expl ai n. 

1. --What is your house the rmosta t setti ng? (OF) summer ; 

wi nter ; fal l a nd spr i ng. --

2. In the 1 as t four years , has your fami ly , ( check where appropri ate ) --

added storm wi ndows --

a dded weatherstri ppi ng or recaul ked wi ndows and/or doors 

added i nsul ati on to house 

3. Homeowner c omments. 

A -8 
Instal l er Code --

Excerpt from Letter to Al l Ins tal l ers : 

We wou l d l i ke to now ask you and your c ompany for an addi ti onal effort in 

provi di ng us i·nformati on concerni ng th e rel i ab i l i ty experi ence you have had in 

general a nd wi th the moni tored systems in parti cul ar. At the same time , we 

wi ll send a l etter aski ng the i ndivi dual homeowners for i nformati on on a ny 

i mpac t the sol ar system h as h ad on thei r dai ly l i ving patterns or the way in 

whi ch they have dec i ded to use thei r sys tems to gai n the most benefi t for 

th emsel ves. We wi ll al so a ttempt to obtain the homeowner 's c omments on 

overal l system operation and any probl ems ; howeve r, we do not anti c i pate that 

the h omeowner i nputs wi ll provide deta i l ed i nformation . 

We wou l d greatl y appreci ate you r aid in compl eti ng two types of data forms 

wh i ch are encl osed . The II A" Data Form is di rectl y concerned wi th the systems 

wh i ch have been in the moni tori ng program . Ou r objecti ve is to col l ect data 

on e ach of the probl ems which were encountered . Th is wi ll be useful in 

gu idi ng future research programs . I mi ght hasten to add , we do see the 

overal l performance of the moni tored systems as qui te good . Hopeful l y , your 

i nputs wi ll hel p mak e even better components avai l ab l e in the future . 

A package of the II A" Da ta Forms is encl osed a l ong wi th Monthly Summary 

sheets from you r mon i tored systems . We ask that you compl �'te a separate "A" 

Da ta Fo rm for each probl em noted on the summari es . We have noted wi th a red 

l i ne eac h i nstance where there appeared to be a probl em . Al so , if you k now of 

other probl ems wh i ch are not l i sted on a performance summary , pl ease compl ete 

an addi ti onal questi onnaire on each such problem. Fortunately , there are not 

too many of these events so your job shoul d not be d i ffi cul t. We do recogni ze 

that you may have to refer to you r own servi ce records or otherwi se "sea rch 

your memory" to provi de ful l detai l s. Pl ease do the best you can to recal l 

each event. If you th i nk that I can hel p by expl a i ni ng any of the coding on 

the performance s heet , pl ease c all. 

After compl eti on of your group of II A" Data Forms , pl ease compl ete the liB II 

Data Form wh ich provi des general i nformati on rel ated to rel i abi lity probl ems 

in the fiel d . We bel i eve that your fi el d experi ence wi th al l of your 

i nstal l ed equi pment is extremely val uabl e for assessi ng the most i mportant 

areas concerning mai ntenance and rel i ab ility. As you k now , fi el d experi ence 

is where system rel i abi l i ty characteri s tics can best be gathered . Th is form 

is sel f-expl anatory a nd does not requi re a ny reference to the performance 

mon i tori ng data . 

A -9 
The addi tional data to be furni shed by you and you r company wi ll only be 

utili zed as part of the stati sti cal data . 

( Fol l owed by closi ng cOlrments a nd expression of a pprec i ati on for the fi rm ' s 

assl stanc e--si gned by Wi lli am M. Jones , Program Manager .) 

Enc l osures: 

Data Form A 

Da ta Form B 

A-10 
DATA FORM A: REVIEW OF PROBLEMS W ITH MON ITORED SYSTEMS 

In troducti on 

Re fer to the Monthly Summary sheets on your moni tored sites whi ch are 

provi ded separately. On these sheets , a ny i denti fied probl em is marked wi th a 

re d l i ne whi ch u sual ly k eys to the date of the occurrence . 

Pl ease compl ete a separate questi onnai re for each probl em usi ng the date 

to differenti ate between two or more probl ems at one site. If you know of a 

robl em not i denti fied on the Monthl y Summa r s heet , l ease i denti f it and 

use t e approxl mate date . 

Tel ephone ESG , - Inc . at ( 404 ) 457-8790 if you have any questi ons . Ask for 

Wi l l i am M. Jones . 

Items as Fol l ows : 

1 • In s ta 11 e r Na me 

Loc ati on ( Ci ty and State ) 

2. Si te Co de ( from Monthly Summary Sheets ) 

3. Ap proximate Date of Probl em 

( from Summary Sheet or other s ources) 

4. Descri be the probl em wi th thi s system , i . e . , what were the symptoms? 

5. How d i d th e h omeowner k now the prob l em exi sted? 

6. Descri be the correcti ve mai ntenance performed on-si te. 

7. Name a ny system components that were repl aced . 

A-l l 
8. Indi cate the cause of the system or component probl em. 

9. Wh at was the cost to the h omeowner for repai r ' or repl acement? 

1 0 . Was the repai r or repl acement cost covered under any warranty? 

11. Di d the i ni ti al fai l ure c ause other probl ems wi th th is system? 

If yes, pl ease descri be . 

1 2. Ad diti onal comments (use � xtra sheet if necessa ry). 

A-1 2 
Insta 11 er Name 

Introducti on 

DATA FORM B: GENERAL SYSTEM FIELD PERFORMA NCE 

Th is is i ntended to u ti l i ze your fiel d exper:-i ence as a key i nsta l l er ir 

your area to obtai n an overview of the most i mpo rtant rel i ab ili ty ana 

mai ntai nabi lity a reas experi enced duri ng the past two years. Pl ease draw on 

you r experi ence wi th al l of you r resi denti al sol ar wate r heater i nsta l l ati on s 

to provi de the ranki ngs a nd other i nformati on requested bel ow. 

Sect; on 1 .Ranki ng and Identi fi cat; on of Probl em Areas Most Frequentl y 

Encoun�ered in the Fi el d 

Step 1: There a re eight categori es l i sted bel ow wh ich represent the areas 

where resi denti al sol ar water heater probl ems occu r. Careful ly 

revi ew these ei gh t c ategori es i denti fi ed by the 1 etters A through H. 

In the box provi ded next to each category , rank the categori es wi th 

the n umbers 1 to 8 wi th the rank of 1 as the most frequent probl em 

area . 

Step 2: After the eight categori es are ranked , pl ease revi ew the i tems or 

characteri sti cs l i sted wi thi n each catego ry. Ci rcl e the two most 

frequent i tems wi thi n each of the e i ght ranked categori es. 

A. 

RANK 

Control l er: (ci rcl e 2 of the fol l owi ng) 

- Pump not runni ng at a l l 

o 

B. 

RANK 

o 

C. 

RANK 

o 

- Pump runni ng at ni ght or when su n not avai l abl e 

- Pump runni ng at al l times 

- Imprope r cal i brati on (reduced effi c i ency even though system 

may operate ) 

Other 

Sensors: (ci rcl e 2 of the fol l owi ng ) 

- De fecti ve 'sensor 

- Faul ty wi ri ng 

- Improper sensor pl acement 

- Other 

Ta nks: (ci rcle 2 of the fol l owi ng) 

- Leak i ng tank (sol ar or conventi ona l ) 

- Co rrosi on or sedi ment bui l dup 

- El ectri c el ement in tank burned out 

- Thermostat setti ng i ndi cati ng wrong temperatu re 

- Other 

A-1 3 
D. 

RANK 

D 

E. 

RANK 

D 

F. 

RANK 

D 

G. 

RANK D 

H. 

Pump: (ci rcl e 2 of the fol l owi ng ) 

- Pump fa i l ure ( col l ector l oop or heat exchanger l oop ) 

- Pump Cavi tati ng (Ai rlock ) 

- Other 

Col l ectors: (ci rc l e 2 of the fol l owi ng ) 

- Co ndensati on on transparent cover 

- Leaki ng pipe in col l ector 

- Broken gl ass cover 

- Fade d gl ass or pl asti c cover 

- Co l l ec tor support structure probl em 

- Other 

Pi pi ng: (circle 2 of the fol l owi ng ) 

- Leaki ng pi pe on roo f 

- Le aking pipe i n-house 

- Pi ping mate ri al deteri orated (pl asti c pi pe ) 

- Pi pi ng i nsul ati on degraded on roof (shrunk or fel l off ) 

- Scal e or corrosi on bui l dup in p i pes 

- Other 

Freeze Damage: (circle 2 of the fol l owi ng ) 

- Saggi ng pi pes trappe d wate r on roo f ( i mproper drai nage ) 

- Co ntrols fai l ed c ausi ng freeze damage 

- Drai ndown val ve fai l ure 

- An ti freeze sol uti on i neffecti ve 

- Other 

Other System El ements: (c i rcle 2 of the fol l owi ng ) 

- Heat exchanger corrosi on or sca l e bui l dup 

, 

- Le aki ng h eat exchanger 

- Drai ndown val ve fai l ure 

- Drai ndown v al ve l eaki ng ( seal s) 

- Vacuum breaker fai l ure 

- Ai r vent fa i l ure 

- Temperi ng val ve defecti ve 

- Pressure/temperature rel ief val ve fai l ure 

- Shadi ng probl ems 

- Water l eak at parti cul ar c omponents or l ocati ons 

- Other 

A-1 4 
Secti on I I General System Pe rfonnance Infonnati on 

Pl ease compl ete the fol l owi ng: 

1. Pl ease i ndi cate the appropri ate percentages of the causes of system 

rel i ability probl ems encountered in the fi el d wi th resi denti al sol a r hot 

water systems. 

---, 

% component fai l ures or mal functi on 

-- 

% i nstal l ati on probl ems , i . e . , sensor l ocati on , pi pi ng , etc . 

poor system desi gn 

1 00 % 

2. P1 ease i ndi cate the a ppropri ate percentages when resi denti al system 

rel i ability probl ems general ly occu r. __

 %, duri ng first week of operati on 

-- 

% duri ng second to fourth week of operati on 

duri ng second to si xth month of operati on 

___ --

% duri ng seventh month to one year of operati on 

____ __

 

-,% duri ng second year of operati on 

% afte r second year of operati on 

1 00 % 

3. Wh at are the major reasons the l isted resi denti al system components e i ther 

faile d or mal functi one d in the fiel d? 

- Pumps ______

__________________________ ____ __ 

- Control s 

--

- Pi pi ng ____________ _____________ ______ _____________ _ 

- Ta nks 

--

- Other Major Components ( i .e. , He at Exchangers, Drai ndown Val ves , etc.) 

Pl ease Li st 

--

A-1 5 
4. Duri ng the fi rst yea r of operati on for a resi denti al sol ar hot water 

system , what is the a verage number of fol l ow-up servi ce cal ls to that 

si te ? 

5. Of these return vi si ts , what is the number of ti mes when the homeowner 

bel i eved there was a probl em , but there actual ly was no probl em? 

6. Instal l er Comments 

A-1 6 
APPENDIX B 

INSTALLER FIELD EXPERIENCES SURVEY RESULTS 

As part of the i nstal l er s urvey forms package , a secti on was i ncl uded to 

gather i nformati on on the overal l fiel d experi ence of the i nstal l ers . ESG 

requested that each i nstal l er c ompl ete this secti on and base the answers on 

his company 's experi ences wi th residenti al sol ar water heaters over the past 

two years . ESG provi ded the i n stal l ers wi th a l i st of ei ght system components 

and probl em - area s categori es and requested that they rank the categori es 

a ccording to frequency of occurrence . The eight categori es are l i s ted in 

Appendi x A on the Instal l er Data Form B. 

As shown in Appendi x A, each of the ei gh t categori es had a n umber of 

subcategori es wh i ch characteri zed a preval ent prob1 em area. The i n stal l ers 

were requested to rank the pr.ob1 em or component category one through ei ght, 

wi th one bei ng the mos t frequent. The two most frequent subcate gori es were to 

be circled by the i nstall ers . Tabl e B�l shows the average val ues for each 

ranked category. Al so shown in Table B-1 are · the two most frequent 

subcategori es a nd the respec ti ve n umber of i nstal l ers whi ch i denti fi ed th is 

subcategory as mos t frequent. 

Th ere were a total of twel ve i nsta l l ers who responded to th is survey. 

Seven i nstal l ers were l ocated in Fl ori da. The remai ni ng fi ve i nstal l ers were 

l ocated as fol l ows : Vi rgi ni a - 3; Georg ia - 1; Al abama - 1. The maj ori ty of 

th e respondi n g i nstal l ers have been in the sol ar i ndustry for over five years 

and , o f. c ourse, none fewer than 2.0 years in busi ness. 

As shown in Tabl e B-1 , the two system components most 1 i kely to have 

probl ems a re control l ers a nd sensors . Control l ers are the most troubl esome 

c omponent. The two most frequent causes of control l er mal func ti on is 

re portedly due to manufacturers ' ci rcui t board defects or power surges 

infl i c ted on the control l er by nearby l i gh tning s trikes . 

B-1 
The most rel i abl e components of the sys tems are reported to be the 

col l ector a nd storage s ubsys tems . The most frequent probl em wi th the s torage 

subsystem is i denti fi ed as the el ectri c el ement burning out. This is actual ly 

a non-sol ar probl em area . Th e col l ector system is i ndi cated as the 1 east 

probl em pl a gued system component. The i nstal l ers reported that when a 

col l ector probl em is real i zed it ;s u sual ly conden'sati on on the gl azi ng or a 

faded pl asti c gl azi ng cover . 

The i nstal l ers I overal l fi el d experi ences c oncerni ng systems operati onal 

rel i ab i lity and ma i ntainabi l i ty is cl osel y al i gned wi th the resul ts from the 

R&M survey of the fiel d test systems . It is encouraging to note the 

similari ty of resul ts and amounts of veri fiabl e data gathered . A compari son 

- o f resul ts from b oth s urveys i ndi cates the fol l owi ng s imi l ari ti es : 

1) The col l ector and storage subsystems are th e two mos t rel i abl e system 

components . 

2) Control l er and sensor mal functions a re two of the most 

frequen t system R&M probl em areas . 

3 ) Drai ndown val ve fai l ures are preval ent causes of system probl ems and 

freeze damage . 

4) Nearby l i gh tni ng s tri kes cause a si gn i fi cant number of control l er 

fa i l ures. 

As menti oned , twel ve i n stal l ers responded to the survey concern i ng an 

overvi ew of thei r respecti ve fi el d experi ences wi th resi denti al sol ar water 

heaters. Th e fol l owi ng are four sel ected questi ons and resul ts from the 

survey forms . The resul ts a re averaged val ue s. 

B-2 
1. Pl ease i ndi cate the appropri ate percentage of the causes of sys tem 

rel i abi l i ty probl ems e ncountered in the fi el d wi th resi denti al sol ar 

hot water systems . 

76 % componen t fai l ures or mal functi ons 

22 % i nstal l ati on probl em i . e . , sensor l ocation , pi pi ng, etc . 

2 % poor system desi gn 

2. Pl ease i ndi cate the appropri ate percentages when resi denti al system 

re1 i abi l i ty prob1 ems general ly occur. 

60 % duri ng fi rst week of o perati on 

5 % duri ng second to fourth week of operati on 

5 % duri ng s econd to s i xth month of operati on 

7 % duri ng seventh month to one yea r of operati on 

8 % duri ng second year of o perati on 

16 % after second yea r of operati on 

3. Duri ng the fi rst year of operati on for a resi denti al sol ar hot water 

system , what is the average number of fol l owu p service cal l s to that 

s i te? 

An swer: 0.9 site visi ts/year 

4. Of these return vi si ts, what is the number of times when the 

homeowner bel i eved there wa s a probl em , but there actual ly was no 

probl em? 

An swer: 37% of the time 

B -3 
PROBLEM 

CATEGORY 

Co ntrol 1 ers 

Sensors 

Oth er System 

El ements 

Freeze Damage 

Pumps 

Pi pi n9 

Tank s 

Col l ectors 

AVERAGE* 

RANK 

2.5 

3.7 

4.0 

4.5 

4.5 

4.9 

5 .0 

6.7 

SUBCATEGORY - two most 

frequent events wi thin each 

probl em category 

- Pump runni ng at night 

- Pump runni ng at al l times 

- De fecti ve sensors 

- Faul ty wi ri ng 

- PIT val ve fai l ure 

Ai r Vent fai l ure 

- Drai ndown val ve fai l ure 

- Saggi ng pi pes 

- Pump c avi tati ng (ai rl ock ) 

- Pump fai 1 ure 

- In sul ati on degradati on 

- El ec tri c el ement fai l u re 

- Thermostat setti ng i ncorrect 

- Conden sati on on gl ass cover 

- Faded gl ass or pl asti c cover 

# of Instal l ers 

Concurri ng ( 1 2 

possi bl e) 

6 

6 

9 

4 

7 

4 

4 

4 

7 

6 

10 

8 

4 

4 

4 

* Average rank is based on a total of 12 i nstal l er rank i n g re sponse s. A 

probl em category is given a ranki ng between 1 a nd 8, with 1 i nd i cati ng the 

most frequent probl em . 

TABLE B-1 . RESULTS FROM I NSTALLER F I ELD EXPERI ENCE SURVEY 

B-4 
STR -2531 

SELECTED DISTRIBUTION LIST 

J ohn Avery 

Los Al amos Nati onal Laboratory 

MS K-573 

P . O. Box 1663 

Los Al amos, NM 87545 

Donal d Bowden 

Sol ar Unl i mi ted, I nc. 

No . 37 Trayl or Isl and 

Huntsvi lle , AL 3�801· 

Kirk Col l i er, Ph .D. 

Col lier Engi neeri ng 

Rt. 2, Box 240 

Cave Creek , AZ 85331 

James Col l ner , Di rector 

Research and Engi neeri ng 

Ameri can Sol ar Ki ng 

P . O. Box 7399 

Waco , TX 767 10 

Jonathan Ben Costa 

Paci fic Gas and El ectri c Co . 

77 Beal e Street 

San Franci sco , CA 94106 

Brad Davis, Vice P resi dent 

Nat'l . Assn . of Sol ar Contractors 

Marc Engi neeri ng Corporati on 

2712 Burgandy Dri ve 

Ci nnami nson, NJ 08077 

Mr. Robert A. Di ehl 

Energy Servi ces 

Bal ti more Gas and El ectri c 

P . O. Box 1475 

Bal timore , MD 21203 

Robert D. Di kkers 

Nati onal Bureau of Standards 

Technol ogy B-148 

Washi ngton , DC 20234 

Webb Farber 

U.S . Sol ar Corporati on 

P.O. Drawer K 

Hampton , FL 32044 

J oe Fri ssora 

Sunmaster Corp . 

35 W. Wi lli am Street 

Corni ng , NY 14830 

Ed Gray 

JRB Associ ates 

8400 W. Park Dri ve 

McLean , VA 22102 

Sal ly Hooks 

Marketi ng Department 

Long Isl and Li ghti ng Company 

250 Ol d Country Road 

Mi neol a, NY 1 1501 

Peter Jacobs 

Novan Energy, I nc. 

1630 N. 63rd St . 

Boul der, CO 80301 

Wi 11 i am M. Jones 

Energy Systems Group 

ESG , Inc . 

223 1 Peri meter Park , Sui te 11 

Atl anta , GA 30341 

Susumu Karak i , 

Sol ar Appl i cati ons Laboratory 

Sol ar House No. 2 

Col orado State Uni versi ty 

Ft. Collins, CO 80523 

Paul W. Kendal l 

Vi tro Laboratori es 

14000 Georgi a Avenue 

Si l ver Spri ng, MD 20910 

Wi lli am J. Kennish 

Vice P resi dent 

TP I, Inc . 

5010 Sunnysi de Avenue , Sui te 301 

Bel tsvi l l e, MD 20705 

J ohn Long 

Tennessee Val l ey Authori ty 

400 Commerce Avenue , SW 

Knoxvi l l e, TN 37902 
Pamel a S. McKeever 

Publ ic Servi ce Co . of N. Mex . 

Al varado Square 

Al buquerque , NM 87 158 

Jack Meeker 

8 Gerri ty Street 

Wi l mi ngton , MA 01887 

Stan Moore 

Los Al amos Nati onal Laboratory 

MS K-571 

P.O. Box 1663 

Los Al amos, NM 87545 

Davi d S. Odegard 

Northern Energy Corporati on 

470 Atl anta Avenue 

Boston , MA 02210 

Andrew J. Parker 

Executi ve Vice Presi dent 

Muel l er Associ ates , Inc . 

1900 Sul phur Spri ng Road 

Bal timore , MD 21227 

Paul J. Pek rul 

Rockwel l ETEC 

P.O . Box 1449 

Canoga Park , CA 91304 

Gary Purcel l 

El ectri c Power Research Insti tute 

3412 Hi l l view Avenue 

Pal o Al to , CA 94303 

Ri chard Ri ttl emann 

Burt , Hi l l, Kosar, 

Ri ttl eman Associ ates 

400 Morgan Center 

Butl er, PA 16001 

Sherry Rossi 

Vi tro Laboratori es 

14000 Georgi a Avenue 

Si l ver Spri ng, MD 20910 

Wi l l i am W. Schertz 

Argonne Nati onal Laboratory 

9700 South Cass Avenue 

Argonne, IL 60439 

Ri chard Si l bergl i tt, Ph .D. 

DHR, Inc . 

6858 Ol d Domi ni on Dri ve 

McLean, VA 22101 

Robert Spears 

STR-2531 

Devel opment Proj ect Di rector 

Reynol ds Products a�d Process 

Devel opment Laboratory 

P . O. Box 27003 

Richmon d, VA 2326 1 

Bi ll Stoney 

RCA Astro El ectroni cs 

P . O. Box 800 

Pri ncton , NJ 08540 

Burt Swerdl i ng 

Proj ect Engi neer 

Grumman Energy Systems, Inc . 

445 Broadhol l ow Road 

Mel vi lle , NY 17747 

Byron Wi nn, Ph .D. 

Mechani cal Engi neeri ng Department 

Col orado State Uni versi ty 

Ft. Col lins, CO 80523 

t4arvin Yarosh 

Fl ori da Sol ar Energy Center 

300 State Road 40 1 

Cape Canaveral , FL 32920 

Sol ar Energy Research I nsti tute 

Crai g Chri stensen 

Robert Farri ngton 

Lawrence Fl owers 

Ronal d J udkoff 

Al l an Lewandowsk i 

Lawrence M. Murphy 

Wal ter Short 
Document Control 1 1. SERI Report No. 1 2. NTIS Accession No. 

Page SERI/STR- 253-253l 

4. Title and Subtitle 

S u rvey of System Operati onal Fa i l ure Modes from 1 22 

Res i denti al Sol ar Wa ter Heater Systems Over a Period 

of Approx i mately Two Years 

7. Author(s) 

Charl es Kutscher 

9. Performing Organization Name and Address 

ESG , Inc . 

Atl anta , Georgia 

12. Sponsoring Organization Name

. 

and Address 

Sol ar Energy Research · I nsti tute 

1 617 Col e Boul evard 

Gol den , Col orado 80401 

15. Supplementary Notes 

Techn i cal Monitor : Charl es Kutscher 

1 6. Abstract ( Limit: 200 words) 

3. Recipient's Accession No. 

5. Publication Date 

October 1 984 

6. 

8. Performing Organization Rept. No. 

10. Project/Task/Work Unit No. 

7 526.10 

11. Contract (C) or Grant (G) No. 

(C) H K-3-03l 28- l 

(G) 

1 3. Type of Report & Period Covered 

Techni cal Report 

14. 

Th is report descri bes the resu l ts of a survey on the operation of .acti ve sol ar 

heati ng and cool i ng systems and thei r components . Questionai res were sent to 

h omeowners and i nstal l ers , coveri ng 1 22 systems . Resul ts were categori zed 

according to probl em severi ty, l ocatiDn , system type , l ength of system operati on , 

and time of the yea r. Approx i ma tely 47% of the systems had at l east one 

rel iabi l i ty probl em over a two-year peri od . Fl at-pl ate col l ector and storage 

systems were highly rel i able. Improper operation of these components was 

a ttri buted to i n sta l l ation probl ems . Dra i nback des i gns al so had the greatest 

rel i ab ility; draindown systems were the l east rel i abl e, l argely because of the 

fa i l u re of dra i ndown val ves . D i fferenti al control l ers caused the l argest number 

of fa i l ures that resul ted in a repa ir cost in excess of $50 to the homeowner . 

17. Document Analysis 

a. Descriptors Effici ency ; Fa i l u res ; Performance ; Rel i ab i l i ty; Res i dential Sector ; 

Sol ar Water Heaters ; Sol ar Water Heati n g ; Surveys 

b. Identifiers/Open-Ended Terms 

c. UC Categories 

59a 

1 8. Availability Statement 

Nati onal Techn i cal Info rmation Servi ce 

u.S. Department of Commerce 

5285 Port Royal Road 

Spri ngfi el d, Virgi nia 221 61 

Form No. 0069 (3-25-82) 

1 9. No. of Pages 

56 

20. Price 

A04