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Research Information Center

Flame Roll-Out Study for GasE“~4r;S

Fired Water Heaters

James Y. Kao

Donald B. Ward

George E. Kelly

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Building Environment Division

Gaithersburg, Maryland 20899

March 1988

Stimulating America's Progress 1913-1988

Sponsored by:

U.S. Consumer Product Safety Commission

Washington, DC 20207

NBSIR 88-3724

FLAME ROLL-OUT STUDY FOR GAS

FIRED WATER HEATERS

James Y. Kao

Donald B. Ward

George E. Kelly

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Building Technology

Building Environment Division

Gaithersburg, Maryland 20899

March 1988

Sponsored by:

U.S. Consumer Product Safety Commission

Washington, DC 20207

U.S. DEPARTMENT OF COMMERCE, C. William Verity, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

ABSTRACT

Five gas-fired water heaters (four natural gas and one LP gas) were tested

in laboratory with simulated home conditions to evaluate their flame

roll-out characteristics. Simulated variables were flue blockage, space

pressure depression, access door status (in-place and not in-place) , and

other related factors. Test results were compared with those based on the

proposed ANSI test method. The testing concludes that, in addition to

flue blockage, pressure depression and door status are major factors in

inducing heater flame roll-out; that poor draft hood performance contributes

to the likelihood of flame roll-out; that the proposed ANSI test method

should add a temperature criterion for determining flame roll-out; that

the proposed ANSI blocked flue test appears to be adequate for units equipped

with thermal spill switches located at their access doors area. For units

not equipped with these particular type of safety devices, the following

concerns were identified: 1) Water heaters which pass the proposed ANSI

test, with the access doors in place and without the need for additional

safety devices, may not pass such a test if the doors were left off, and

2) units which use devices other than thermal switches to detect blocked

flues, may pass the proposed ANSI test and still produce dangerous flames

and heat outside of their jackets under certain conditions. Recommendations

are made that CPSC and the ANSI sub-committee on water heaters consider

also requiring the interlocking of access doors with water heater operation,

the use of temperature sensing as a means of detecting flame roll-out, and

the use of improved draft hood designs and draft hood performance testing

to reduce the chances of flame roll-out.

Key Words

Flame roll-out; gas fired water heater; gas water heater;

safety; water heater; water heater test

iii
ACKNOWLEDGEMENTS

This study was sponsored by the U.S. Consumer Product Safety Commission

(CPSC) . The CPSC project manager is Donald Switzer. The authors also

wish to thank Thomas (Rocky) Somers and Antonio Crespo for their assistance

in conducting experiments.

iv
TABLE OF CONTENTS

Page

ABSTRACT iii

ACKNOWLEDGEMENTS iv

LIST OF TABLES vii

LIST OF FIGURES viii

SI CONVERSION FACTORS xi

1. INTRODUCTION 1

2. CONCLUSIONS AND RECOMMENDATIONS 4

3. TEST HEATERS AND TEST APPARATUS 7

3.1 Test Heaters 7

3.2 Test Chamber and Facility 8

3.3 Instrumentation 9

4. TESTS AND TEST PROCEDURES 12

4.1 Definition of Flame Roll-out 12

4.2 Chamber Depression Test 12

4.3 Access Door Status 14

4.4 Flue Blockage Test 14

4.5 Burner Cyclic Test 15

4.6 Thermal Vent Damper Test 15

4.7 General Test Conditions 16

4.8 Test Procedures 17

4.8.1 Burner Cyclic Test 17

4.8.2 Chamber Pressure Depression and Flue

Blockage Test 18

v
Page

5. TEST RESULTS AND DISCUSSION 19

5.1 Data Presentation of Test Results 19

5.2 Stack Flow 20

5.3 Heater 1 Results 20

5.4 Heater 2 Results 23

5.5 Heater 3 Results 25

5.6 Heater 4 Results 28

5.7 Heater 5 Results..... 30

5.8 Summary of Test Results 32

5.8.1 Flue Inversion and Flame Roll-out 32

5.8.2 Flame Roll-out Temperature 35

5.8.3 Comparison with Proposed ANSI Test

Method 39

REFERENCES 42

vi
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5

6

7

8

9

10

11

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13

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31

32

33

34

LIST OF TABLES

Test water heaters

Air temperature at heater door, control, and

base for heater 1 with access doors in-place

under pressure depression tests

Air temperature at heater door, control, and

base for heater 1 with access doors not

in-place under pressure depression tests

Air temperature at heater door, control, and

base for heater 2 with access doors in-place

under pressure depression tests

Air temperature at heater door, control, and

base for heater 2 with access doors not

in-place under pressure depression tests

Air temperature at heater door, control, and

base for heater 3 with access doors in-place

under pressure depression tests

Air temperature at heater door, control, and

base for heater 3 with access doors not

in-place under pressure depression tests

Air temperature at heater door, control, and

base for heater 4 with access doors in-place

under pressure depression tests

Air temperature at heater door, control, and

base for heater 4 with access doors not

in-place under pressure depression tests

Air temperature at heater door, control, and

base for heater 5 with access doors in-place

under pressure depression tests

Air temperature at heater door, control, and

base for heater 5 with access doors not

in-place under pressure depression tests

Flame roll-out occurrences for cyclic tests...

Flame roll-out occurrences for pressure

depression tests

vii
Page

Table 14 Results of pressure depression tests using

a criterion of 250°F outside the access

doors for hot gas spillage 36,37

Table 15 Comparison of proposed ANSI test and

pressure depression test results 41

viii
LIST OF FIGURES

Page

Figure 1 Schematic diagram showing sensor locations

for temperature, pressure, and gas

concentration 43

Figure 2 Cyclic test, access doors in-place

-- Heater no. 1 44,45

Figure 3 Cyclic test, access doors off

-- Heater no. 1 46,47

Figure 4 Pressure test, access doors in-piace,

no flue blockage -- Heater no. 1 48,49

Figure 5 Pressure test, access doors in-place,

20% flue blockage -- Heater no. 1 50,51

Figure 6 Pressure test, access doors in-place,

60% flue blockage -- Heater no. 1 52,53

Figure 7 Pressure test, access doors in-place,

100% flue blockage -- Heater no. 1 54,55

Figure 8 Pressure test, access doors off, no flue blockage -- Heater no. 1 56,57

Figure 9 Pressure test, access doors off,

20% flue blockage -- Heater no. 1 58,59

Figure 10 Pressure test, access .doors off,

60% flue blockage -- Heater no. 1 60,61

Figure 11 Pressure test, access doors off,

100% flue blockage -- Heater no. 1 62,63

Figure 12 Cyclic test, access doors in-place

-- Heater no. 2 64,65

Figure 13 Cyclic test, access doors off

-- Heater no. 2 66,67

Figure 14 Pressure test, access doors in-place,

no flue blockage -- Heater no. 2 68,69

Figure 15 Pressure test, access doors in-place,

20% flue blockage -- Heater no. 2 70,71

Figure 16 Pressure test, access doors in-place,

60% flue blockage -- Heater no. 2 72,73

ix
Page

Figure 17 Pressure test, access doors in-place,

100% flue blockage -- Heater no. 2 74,75

Figure 18 Pressure test, access doors off, no flue blockage -- Heater no. 2 76,77

Figure 19 Pressure test, access doors off,

20% flue blockage -- Heater no. 2 78,79

Figure 20 Cyclic test, access doors in-place

-- Heater no. 3 80,81

Figure 21 Cyclic test, access doors off

-- Heater no. 3 82,83

Figure 22 Pressure test, access doors in-place,

no flue blockage -- Heater no. 3 84,85

Figure 23 Pressure test, access doors in-place,

20% flue blockage -- Heater no. 3 86,87

Figure 24 Pressure test, access doors in-place,

60% flue blockage -- Heater no. 3 88,89

Figure 25 Pressure test, access doors in-place,

100% flue blockage -- Heater no. 3 90,91

Figure 26 Pressure test, access doors off, no flue blockage -- Heater no. 3 92,93

Figure 27 Pressure test, access doors off,

20% flue blockage -- Heater no. 3 94,95

Figure 28 Pressure test, access doors off,

60% flue blockage -- Heater no. 3 96,97

Figure 29 Pressure test, access doors off,

100% flue blockage -- Heater no. 3 98,99

Figure 30 Cyclic test, access doors in-place

-- Heater no. 4 100,101

Figure 31 Cyclic test, access doors off

-- Heater no. 4 102,103

Figure 32 Pressure test, access doors in-place,

no flue blockage -- Heater no. 4 104,105

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Page

Figure 33 Pressure test, access doors in-place,

20% flue blockage -- Heater no. 4 106,107

Figure 34 Pressure test, access doors in-place,

60% flue blockage -- Heater no. 4 108,109

Figure 35 Pressure test, access doors in-place,

100% flue blockage -- Heater no. 4 110,111

Figure 36 Pressure test, access doors off, no flue blockage -- Heater no. 4 112,113

Figure 37 Pressure test, access doors off,

20% flue blockage -- Heater no. 4 114,115

Figure 38 Pressure test, access doors off,

60% flue blockage -- Heater no. 4 116,117

Figure 39 Pressure test, access doors off,

100% flue blockage -- Heater no. 4 118,119

Figure 40 Cyclic test, access doors in-place,

no flue blockage -- Heater no. 5 120,121

Figure 41 Cyclic test, access doors in-place,

60% flue blockage -- Heater no. 5 122,123

* Figure 42 Cyclic test, access doors off, no flue blockage -- Heater no. 5 124,125

Figure 43 Cyclic test, access doors off,

60% flue blockage -- Heater no. 5 126,127

Figure 44 Pressure test, access doors in-place,

no flue blockage -- Heater no. 5 128,129

Figure 45 Pressure test, access doors in-place,

20% flue blockage -- Heater no. 5 130,131

Figure 46 Pressure test, access doors in-place,

60% flue blockage -- Heater no. 5 132,133

Figure 47 Pressure test, access doors in-place,

100% flue blockage -- Heater no. 5 134,135

Figure 48 Pressure test, access doors off, no flue blockage -- Heater no. 5 136,137

xi
Page

Figure 49 Pressure test, access doors off,

20% flue blockage -- Heater no. 5 138,139

Figure 50 Pressure test, access doors off,

60% flue blockage -- Heater no. 5 140,141

Figure 51 Pressure test, access doors off,

100% flue blockage -- Heater no. 5 142,143

xii
SI CONVERSION FACTORS

MULTIPLY BY TO OBTAIN

Btu 1.055 kJ

Btu/h 0.293 W

°F °C = ( °F - 32)/l .

ft 0.3048 m

inch 25.4 mm

inch of water (60°F) 249 Pa

xm

1 . INTRODUCTION

According to data gathered by the U.S. Consumer Product Safety Commission

(CPSC) , during the year 1983 there were an estimated 9400 fires in the

United States involving gas fired residential water heaters resulting in

an estimated 1060 injuries and 60 deaths [1]. Like any heat producing

appliance, fire safety issues are of concern in the correct design,

installation, and use of gas fired water heaters. These include clearances

from appliances and exhaust vents to surrounding combustibles, protection

of combustible flooring beneath the appliance, and appropriate venting of

the exhaust.

One significant fire hazard pattern identified by CPSC is the ignition of

combustible materials stored near the heaters. Under certain known failure

conditions, flames or hot combustion products from a water heater can

spill from the combustion chamber and ignite nearby materials [1],

Although good housekeeping may reduce the chance of fires, the CPSC

believed that water heaters needed to be examined for possible malfunctions

due to adverse operating conditions in order to prevent flames and hot

combustion products from exiting at undesirable locations.

To this end, CPSC funded the Calspan Corporation in September of 1984 to

test water heaters under atmospheric pressure with the flues constricted

to various degrees in order to confirm the occurrence of flame roll-out at

the access doors [2] . The study indicated that when the flue area reduction

was 60% and higher, the air temperature at the access doors reached over

1
250°F with the pilot access doors in place. The study also investigated

means to prevent possible ignitions of combustible materials stored near

water heaters and suggested that thermally operated spill switches would

appear to substantially reduce the potential hazard due to spillage under

the conditions tested in the study.

Subsequently, the Water Heater Subcommittee of the American National

Standards Institute (ANSI) issued a proposed change to the standard for

gas water heaters of inputs not greater than 75,000 Btu per hour (ANSI

Standard Z21.10.1) [3]. The proposed standard revisions [4] require that

water heaters be tested with progressively blocked flue outlets. An

initial blockage of 20% of the flue area is increased at 20% increments

until the entire flue area is blocked. The proposed revisions requires

that water heaters must not issue flames outside the face of their jackets

during the tests, and they must operate normally after the tests. A

safety shutoff means would have to be provided to shut off gas to the

water heater for any unit which could not pass this blocked flue test

without such a device.

In the fall of 1986, CPSC contracted with the National Bureau of Standards

(NBS) to do further tests on gas water heaters. This study was limited to

a examination of flame roll-out and spillage from the access door and the

bottom of typical residential water heaters. The contract required that

flame roll-out and combustion chamber spillage characteristics of water

heaters be tested in the laboratory using five CPSC-supplied heaters.

CPSC specifically identified access doors status (in-place or not in-place)

2
and house pressure variations caused by exhaust fans, clothes dryers, and

the like as the main factors to be studied. NBS was also required to

compare and evaluate the test results against the results of the same

water heaters tested under the proposed revisions to the ANSI standard in

order to try to identify possible deficiencies in the proposed ANSI

standard revisions.

3
2. CONCLUSIONS AND RECOMMENDATIONS

Extensive laboratory tests were conducted to establish the flame roll-out

behavior of the five water heaters. Based on the five water heaters

tested, the following conclusions and recommendation are presented:

a. In the laboratory tests, pressure depression is a major factor in

water heater flame roll-out. Depressurization can cause flame roll-out

and reversal of flow in the flue, and can accelerate flame roll-out under

flue blockage conditions. Sustained flame roll-out occurred frequently,

with no flue blockage or partial flue blockage, when negative pressure was

applied to the test chamber. Test chamber pressures ranging from -0.05"

to -0.25" water column (w.c.) produced flame roll-outs frequently. This

pressure range is believed to be within the range of pressure variations

possible in residential homes.

b. During cyclic tests, no sustained flame roll-out was observed for

the natural gas water heaters. With access doors in-place and without

pressure depression during the cyclic tests, the LP-gas heater did not

have flame roll-out when the flue was partially blocked. However,

sustained flame roll-out occurred during pressure-depression cyclic tests

for the LP-gas heater, regardless of door status. The proposed ANSI test

method does not require cyclic tests, and consequently, would not have

detected the flame roll-out observed with the LP-gas heater.

c. Sometimes, flame roll-out was difficult to detect visually during

4
the laboratory tests. The proposed ANSI test method should specifying a temperature level outside the jacket in determining flame roll-out.

d. Closing the inner and outer access doors (throughout this report,

the term access doors mean both the inner and outer access doors) properly

is an important factor affecting flame roll-out. Without the access doors

in-place, the temperature outside the jacket exceeded 250 F in the

majority of the tests with flue blockage and pressure depression. Based

on this criterion, all five heaters would be fire hazards, even though

four heaters would likely pass the proposed ANSI test with the access

doors in-place. Because of this, it is recommended that the CPSC and the

ANSI subcommittee on water heater standards consider requiring an interlocking

device or other means to assure proper access door closure during heater

operation and a method to test for proper operation of the interlocking device.

e. The design of water heater components, such as combustion chamber,

heat exchanger turbulator, and draft hood, plays an important roll in flame

roll-out. The performance of the latter was found to be particularly

important during the pressure depression tests. As a result, it is

recommended that the CPSC and the ANSI subcommittee on water heaters

considering requiring heater manufacturers to strengthen draft hood

performance in order to reduce the possibility of flame roll-out caused by

negative pressure induced flue reversal. A test procedure to test the

effectiveness of draft hoods in preventing flow reversal of the flue gas

should also be considered as possible revisions to the proposed ANSI water

heater standard and the ANSI draft hood standard (American National

5
Standard for Draft Hoods, ANSI Z21.12) [5].

f. Consideration should also be given by the CPSC and the ANSI water

heater subcommittee to requiring the use of thermal devices (as opposed to

other types, such as pressure devices, etc.) for detecting flame roll-out.

Coupling this requirement with door interlocking devices, improved draft

hoods, and the ANSI flue blocked tests, is likely to provide greater

protection against the occurrence of flame roll-out than what is provided

by the current revisions to the ANSI standard.

6
3. TEST HEATERS AND TEST APPARATUS

3.1 Test Heaters

The five test heaters were selected and supplied by CPSC. These heaters

were considered by CPSC to be representative of those available on the

market, but consists of only a small fraction of the total number of

models being sold. In addition, since each model tested was different, no statistical inferences can be made for that model. As a result, the

testing conducted by NBS is not to be interpreted as a statistically valid

quality control analysis but rather as a study to provide CPSC with general

information which would be useful in their efforts to reduce water heater

accidents

The water heater capacities, dimensions, and fuel data are shown in table 1.

Table 1 Test Water Heaters

HEATER NO. 1 2 3 4 5 NAMEPLATE

INPUT, Btu/h 30,000 40,000 40,000 35,000 34,000

STORAGE

CAPACITY, GAL 30 29 40 40 40

OVERALL

HEIGHT, INCH 56 59 59.5 48 47.5

OUTSIDE DIA.

INCH 18.5 16 17 20.25 20

GAS TYPE NATURAL NATURAL NATURAL NATURAL LPG

7
The construction of the heat exchanger turbulators of these heaters varied

considerably in their arrangements and shapes. The draft hoods of heaters

1, 2, 4, and 5 were of similar configuration -- stamped metal with

openings at the top around the periphery and a flat metal blockage at the

center. The draft hood of heater 3 was of a different construction. It

was shaped with a concave bottom facing downward. The inner access doors

of the heaters were similar although some could be closed tighter than

others. The outer access doors differed considerably, but all had fairly

large openings for gas and thermocouple tube access. The outer access

door of heater 1 was flush with the heater outer surfaces and could be

closed tightly. Heaters 2, 4, and 5 had doors that extended outside the

outer surfaces with their tops and bottoms open. The access door of

heater 3 was flush with the jacket except at gas tubes where the top and

bottom of the outer door was open. Control thermocouple and pilot light

arrangements and locations were somewhat different among the heaters.

3.2 Test Chamber and Facility

A metal cabinet approximately 4-feet wide, 4-feet deep, and 7-feet high

was fabricated as the test chamber. It was placed in a test laboratory

which was air-conditioned to maintain a nominal temperature of 70 F. The

test chamber had gasketed double doors on both sides for access and

safety. A plexiglass observation port facing the heater access doors was

used to observe flame roll-out. Two adjustable openings were provided on

the back wall of the chamber for combustion air intake. The test chamber

had a double floor approximately 6 inches from the laboratory floor. The

space between the double floors was connected to the inlet side of an

8
exhaust fan. A variable-speed fan control was used to maintain desired

negative pressure levels in the chamber. Air openings from the laboratory

to the test chamber and from the test chamber to the double floor space

had baffles and distributing plates to evenly distribute air flow within

the chamber. A three-inch diameter, 5-foot high vent pipe penetrated the

test chamber roof, venting the combustion products to the test laboratory.

Heater control valves were protected with thermal shields to prevent them

from being damaged by high temperature.

3.3 Instrumentation

Figure 1 depicts the temperature, pressure, and combustion gas sensor

locations. Depending on the anticipated temperature, Type T

(copper-constantan) and Type K ( chrome 1-alumel) thermocouples were used to

sense the temperatures at the following locations: upper part of water

storage tank, lower part of water storage tank at the same elevation as

the heater temperature control sensor, upper part of flue about 6 inches

below flue top, lower part of flue at the flue bottom, adjacent to pilot

thermocouple, inside vent stack, below draft hood in the path of relief

air (referred to as "draft hood" sensor in this report), test chamber,

four sensors evenly located on the heater outside jacket approximately 1/2

inch above access door ("door" sensor), on the gas supply tube below the

heater control valve ("control" sensor), and one each on both sides of the

heater base. These temperature sensors not only provided heater operating

data, they also assisted in providing flame roll-out and other event

indications. The sensors in the stack and below the draft diverter would

indicate when the stack flow was inverted. The sensors in the flue would

9
indicate when the flue flow was reversed. The sensors above access doors,

at control, and at heater base were used to detect flame roll-out and

combustion air spillage. The sensor beside the pilot thermocouple could

indicate condition of the burner flame as well as the extinguishing of

burner and pilot. Mainly due to the difference in pilot arrangement among

heaters, the temperature of this sensor had considerable variations.

A pressure sensing probe was located in the test chamber at approximately

the same height as the burner to detect chamber pressure during pressure

depression tests. A differential pressure cell with one probe located in

the flue bottom and the other probe located in the test chamber provided

the draft readings of the flue just above the combustion chamber.

Electrical signals for both chamber pressure and flue draft were fed into

electronic manometers for data transmission. It should be noted that the

flue draft data presented in this study should only be viewed as relative

values for the particular heater tested, since air turbulence caused by

combustion and poor air flow conditions (at entrance and exit of pressure

instrumentation) inherently prevented ideal draft data collection.

Combustion gas samples were continuously drawn from the top of the flue.

An infrared gas analyzer was used to monitor and record the carbon

monoxide and carbon dioxide concentration of the combustion products.

These gas concentration levels could indicate when flue flow inversion

occurred. However, during some flue blockage tests, the carbon monoxide

level of the combustion products exceeded the instrumentation range

because of low combustion air supply.

10
All temperature, pressure, and combustion gas data discussed above were

fed into a data logger at 30-second intervals and were concurrentlytransmitted to a micro-computer for recording and analysis.

The carbon monoxide and carbon dioxide levels of the test chamber,

barometric pressure, and the voltage output of the heater pilot thermocouple

were also monitored during the tests. However, they were not part of the

automatic data acquisition system.

11
4. TESTS AND TEST PROCEDURES

4.1 Definition of Flame Roll-out

Flame roll-out is a term generally used to represent hot air or flames

escaping from the lower part of a water heater. In the proposed revisions

to the ANSI standard for gas water heaters, flame roll-out is described as "flames issue outside the face of the jacket" of a water heater. In this

study, flame roll-out is defined as either visible flames issued outside

the face of the jacket or hot combustion products spilled out from the

lower part of a heater. Due to the difficulty in observing the presence

of flames outside the face of the heater jackets, this study uses an air

temperature of 250 F outside the access doors as a criterion for flame

roll-out. This 250 F is the spill switch setpoint recommended by the CPSC

staff [6] as a result of the Calspan study [2] and was chosen only as an

indication of hot gas spillage from the heater. It should not be interpreted

as an NBS recommended criterion for alleviating the hazard of ignition of

combustibles adjacent to water heaters.

4.2 Chamber Pressure Depression Test

The degree of negative pressure inside a house depends on the sources

which create the negative pressure and the tightness of the house. The

sources often found include air exhaust appliances such as clothes dryers

and exhaust fans, heating appliances such as furnaces and water boilers,

and fireplaces. An air circulation fan of a hot air furnace, depending on

the furnace location and the air distribution system arrangement of the

house, may also create negative pressure in the furnace room or other

12
areas of the house. Even hot water heaters themselves may contribute

negative pressure in houses. Outside weather conditions also influence

house pressure. Prevailing wind, terrain effect, and outside air temperature

may all contribute to pressure differences within a house. The recent

emphasis to make houses tighter for energy conservation purposes further

exasperates the problem of house pressure depression.

House pressure depression may overcome the stack draft of heating

appliances and spill combustion products into the home. When substantial

pressure depression exists, the stacks themselves become an air infiltration

route. The in-rush of air through the stacks may enter heat exchangers of

water heaters and alter the normal operations of the heaters. Large-scale

field surveys on house pressure variations which take all these factors

into account are difficult to perform and costly and are not available at

present. However, previous research projects of limited scope indicated

that substantial negative house pressure existed. A survey conducted in

Canada [7] revealed that some houses had pressure depressions over 0.07"

water column. A study [8] combining exhaust fan, clothes dryer, furnace,

and fireplace air requirements and air infiltration data from tests done

by others showed theoretically, that indoor pressure depression might

reach 0.27" water column for a well-sealed single family detached house.

Evidently, a large range of pressure depression may be present in most of

the residential housing stock when all relevant factors are combined.

Based on these studies [7,8], it was determined that a peak negative

pressure of 0.2 to 0.25" water column should be created for the laboratory

tests in this investigation. Pressure steps of 0.05" water column were

13
employed to cover the entire pressure range from neutral to the peak

negative pressure.

4.3 Access Door Status

Preliminary tests on a water heater previously tested by NBS (referred to

as the NBS heater in this report) similar to the five CPSC test heaters,

confirmed that the access door status (in-place or not in-place) made

substantial difference in flame roll-out behavior of the heater. Although

water heater manufacturers post notices to home owners to replace doors

after servicing, the Calspan study [2] concluded that "these doors might

be expected to be improperly installed or not installed at all in a large

number of actual residences" due to the difficulty of properly placing

them. Therefore, all tests in this study were conducted both with the access

doors (both inner and outer doors) in-place and not in-place on all the

heaters

4.4 Flue Blockage Test

The proposed ANSI test procedure requires that water heaters be tested

with flues blocked at 20% increments from 0% to 100% blockage with the

ambient pressure maintained at neutral. During this study the flue

outlets were blocked at 0%, 20%, 60%, and 100%. The intermediate blockage

at 40% and 80% were not used because preliminary tests of this investigation

and the Calspan study showed that above 60% blockage the temperature of

hot air spillage increased substantially. The flue blockage tests were

performed with these four blockages combined with different pressure

levels of test chamber ranging from neutral up to negative 0.25" water

14
column as described previously.

4.5 Burner Cyclic Test

As stated previously, when a house is under negative pressure, the in-rush

of air through the water heater stack may enter the heat exchanger of the

heater in spite of the draft hood. This is especially true when the

burner of the heater is not in operation. The temperature in the flue at

the heat exchanger baffle may at times be lower than the hot water

temperature in the storage tank. When the thermostat of the heater calls

for heat, it may take some time for the flue to establish a draft, during

which time spillage is likely to occur. Therefore, cyclic tests were

performed at various negative chamber pressures up to 0.2" water column to

evaluate flame roll-out during burner startup. During each cyclic test, the

storage water was heated to the test temperature of approximately 140 F

and the heat exchanger temperature was allowed to stabilize. Then hot

water was drawn to start the burner. This simulated a burner startup

during morning usage (heavy demand after extended standby)

4.6 Thermal Vent Damper Test

During the preliminary test on the NBS heater, the vent stack of the test

facility was blocked to simulate a failed thermal vent damper. Blocking

of the stack also simulated a thermal vent damper not responding to burner

ignition when severe house negative pressure prevented the damper from

coming in contact with hot combustion air of the water heater. Test data

indicated that the failed damper did not appear to contribute to flame

roll-out. The damper actually worked as a baffle to prevent air from

15
entering the test chamber. Therefore, the thermal vent damper test was

not incorporated in tests of the five CPSC supplied heaters.

4.7 General Test Conditions

Before a heater was installed for test, the air turbulator of the heat

exchanger was removed and observed visually for carbon deposits and

general conditions. This examination was also conducted after the heater

tests were completed. There was no noticeable increase in carbon deposits

caused by the tests. After heater installation, the thermostat setting

was adjusted to maintain a cutoff temperature of approximately 140 F. The

gas inlet pressure was adjusted as recommended by the heater manufacturer.

For natural gas heaters (no. 1 through 4) the gas pressure was 4.5 or

5" water column. Heating values during the tests varied between 1025 and

1070 Btu per cubic foot. Heater no. 5 was tested with propane gas

(heating value 2558 Btu per cubic foot) and the inlet pressure was

adjusted to 11" water column. The combustion air openings of the test

chamber were adjusted so that when the burners of the heaters were on and

the chamber doors were closed, no noticeable change in the the concentration

of carbon monoxide and carbon dioxide of the flue gas were observed.

Then, the burner control was turned on to run a full thermostatic cycle.

The purpose of this test was to make certain that all heater settings and

operations and the data acquisition system were working properly. One

full thermostatic cycle usually took longer than 24 hours.

There were no major modifications to the heaters, except for minor changes

for installation of testing instrumentation. The anode rods of some

16
heaters were removed to facilitate the installation of water temperature

sensors . Plastic drain valves of some heaters were replaced with metal valves .

4.8 Test Procedures

Each heater was tested according to the following sequences:

4.8.1 Burner Cyclic Test

Cyclic tests were performed in two series -- with access door in-place and

removed. In each series, the chamber pressure was initially set at

neutral and tests repeated at -0.05" water column steps until the pressure

reached -0.2" water column. All heaters were tested without flue blockage

and 10 cyclic tests were conducted for each heater. Since the burner of

heater 5 continued to burn after flue flow was inverted at -0.2" water

column, tests for this heater were repeated with 60% flue blockage. In

each cyclic test, the following procedures were followed:

a. Performed tests with access doors in-place, then with doors off.

b. Burner control was turned on to heat the water to the set temperature.

c. After burner was cut off by the thermostat, a 30-minute wait was

allowed to stabilize the heat exchanger temperature.

d. Test chamber pressure was adjusted to the desired level.

e. Waited 5 minutes to stabilize heater conditions.

f. Discharged hot water to ignite burner.

g. Let burner run for five minutes, then terminated the test.

h. If sustained flame roll-out occurred, tests would be repeated with

60% flue blockage. This was done for heater 5 only, with the flue

17
blocking being done after step c above.

4.8.2 Chamber Pressure Depression and Flue Blockage Test

Tests were first conducted with access doors in-place, then with doors

off. The following procedures were followed during each test:

a. Burner control was turned on to heat the water to the set temperature.

b. Adjusted water valve to maintain the burner on during the test.

c. Blockage installed on top of flue outlet. Blocking flue is part

of the proposed ANSI test procedure.

d. Let heater run for 5 minutes to stabilize all conditions.

e. Set chamber pressure as desired for test, starting from neutral.

f. Continued to run heater for 5 minutes.

g. Decreased chamber pressure one step (0.05" water column) and

repeated steps e and f above until chamber pressure reached

-0.25" water column.

h. If the burner extinguished during any test (not caused by water

temperature control) , lower chamber pressure tests in the same

series (same door status and flue blockage) were not done.

i. If fire rolled out during any stage of the pressure level tests or

there was danger of damaging the heater, the test was terminated

by either returning chamber pressure to neutral or turning off the

gas control valve.

18
J

5. TEST RESULTS AND DISCUSSION

5.1 Data Presentation of Test Results

Test data are presented in figures 2 through 52. Each figure shows the

results of a series of tests and consists of 6 sub-figures. Sub-figure (1)

shows the chamber pressure depression and the flue draft. The chamber

depression is presented in positive values for easy comparison. The flue

draft is expressed as 10 times the test data. As explained in the

instrumentation section, it is not appropriate to compare flue draft among

heaters. Major events which happened during the test such as the status

of the burner, stack inversion, and flue inversion are also indicated in

sub -figure (1) . Sub -figure (2) shows the four temperature readings of the

sensor located outside and above the access door openings. Sub-figure (3)

depicts the temperature outside the access door below the control valve,

and at the left and the right sides of the heater base. Sub-figure (4)

gives the temperatures at the flue top, flue bottom, and at the pilot

light. Although the flue top temperature may be affected sometimes by

downward airflow from the stack during chamber pressure depression tests,

it does assist in determining the flue flow direction. Since the pilot

light and control thermocouple arrangement of different heaters may be

quite different, large variations of temperature readings at pilot lights

may be found on different heaters. Sub-figure (5) shows temperatures

inside the stack and at the air relief opening of the draft hood.

Sub- figure (6) provides carbon dioxide readings at the flue top and can be

used to confirm flue flow inversion.

19
Since flame roll-out is a basic concern of this study, tables 2 through 11

shows the maximum temperatures recorded at heater doors, below control

valves, and at heater bases. The maximum door temperature is the highest

temperature of the four door sensors during the test period.

5.2 Stack flow.

The flow direction of the stack reversed when the chamber pressure was

dropped to -0.05" water column. Since the drafts of the vent stack during

the tests of the five heaters varied within a very small range, regardless

of the door status and the extent of flue blockage, stack flow reversing

occurred for all tests below 0.05" water column pressure depression.

5.3 Heater 1 results.

a. Cyclic Test

For both doors in-place and doors not in-place tests (figures 2 and 3),

the burner was ignited and then burned normally at neutral and -0.05" water

column chamber pressure. While the chamber pressure was at -0.1" water

column and lower, the burner self -extinguished in about 5 to 7 seconds

after it was ignited and rolled out. Readings of the control thermocouple

indicated that the fire extinguishing was not caused by the shutting off

of gas valves. Hot air spilled out momentarily from the access door

opening when the burner was ignited with access doors off. However, none

of the door, control, and heater base temperatures reached 150 F.

20
b. Chamber Pressure Depression Test

With access doors in-place, flue flow inversions or flame roll-out

occurred at -0.15” water column depression with no flue blockage, and at

-0.1" water column with 20% and 60% blockage (figures 4, 5, and 6).

Sub-figure (1) indicate that the flue draft was decreased by either flue

blockage or chamber pressure drops. When flue inversion occurred, the

burner extinguished in less than 5 seconds, probably caused by flow

stagnation and lack of combustion air in the combustion chamber. With

fairly tight access doors, the door temperature did not change greatly.

The temperature sensors at the control and at the heater base registered a sudden jump, although they never exceeded 150 F. Table 2 gives the door,

control, and heater base temperatures of the tests.

With access doors off (figures 8, 9, and 10), flue flow inversion or flame

roll-out occurred at -0.15", -0.2", and -0.05" water column with 0%, 20%,

and 60% blockage, respectively. The burner extinguished 5 to 15 seconds

after the flue flow inverted. Hot gas spilled out from the door opening

when flue blockage or lower chamber pressure was applied. Two door

temperature sensors registered over 300 F at times.

When the flue opening was totally blocked (figures 7 and 11), flame

roll-out occurred regardless of door status, although small notches at the

flue top (notches on the flue to accept air turbulator) kept a very small

amount of combustion product flowing upward in the flue. There was no substantial temperature change at the door, control, or heater base when

access doors were in place (see table 2)

21
Table 2 Air temperature at heater door, control, and base

for heater 1 with access doors in-place

under pressure depression tests

Flue

blockage

Test

chamber

pressure

in. w. c

Maximum

at

door

°F

Maximum

at

control

°F

Maximum

at

base

°F

0% neutral 86.,9 81.,0 80.,8

-0.05 95,.2 84.,0 85.,6

-0.1 97.,0 83.,7 88,,9

-0.15 108..9 97.,9 143..1

20% neutral 97,.0 82.,9 87,.4

-0.05 101,,5 85..3 91,.6

-0.1 110,.5 97..5 125,.1

60% neutral 103..3 83,.5 91,.4

-0.05 106,.7 84,,9 94,.1 -0.1 110,,5 94,.8 126,,0

100% neutral 270,.7 143,.6 110,.5

Table 3 Air temperature at heater door, control, and bas

for heater 1 with access doors not in-place

under pressure depression tests

Test Maximum Maximum Maximum

Flue chamber at at at

blockage pressure door control base

in.w.c. °F °F °F

0% neutral 138.7 86.7 96.4

-0.05 155.8 91.9 99.3

-0.1 202.1 110.3 103.3

-0.15 230.9 119.8 106.3

20% neutral 144.5 79.9 90.0

-0.05 184.8 86.9 94.3

-0.1 236.7 102.0 99.51

-0.15 342.1 114.1 102.7

-0.2 315.3 125.2 105.6

60% neutral 272.8 85.5 97.3

-0.05 317.8 106.2 99.7

-0.1 334.6 113.9 101.8

100% neutral 660.7 89.6 99.3

22
However, one door temperature sensor reached over 600 F when access doors

were off (see table 3) . The burner did not extinguish during these two

tests until the gas valve was manually turned off.

5.4 Heater 2 Results

a. Cyclic Test

The results for heater 2 were similar to those for heater 1, although the

hot air spillage outside the heater was much more severe (figures 12 and

13). The flue inverted at -0.15 and -0.2" water column chamber pressure.

When flue inversion occurred at -0.15" water column and with access doors

off, the temperature momentarily reached approximately 400 F at the door

opening and above 300 F at the control. It took 6 to 14 seconds for the

burner to extinguish after ignition.

b. Chamber Pressure Depression Test

With access doors in-place, flue inversion or flame roll-out occurred at

-0.25" water column chamber pressure with no flue blockage, at -0.2" water

column with 20% blockage, and at -0.1" water column with 60% blockage

(figures 14, 15, and 16). The maximum air temperature at door sensors

(table 4) was close to 1000 F and at control sensor was close to 800 F.

At 100% flue blockage (figure 17) , fire rolled out from access doors

raising door temperature to over 450 F, although test data indicated that

the flue flow was not inverted. Flames were visible during all blockage

tests except for 100% blockage.

23
Table 4 Air temperature at heater door, control, and base

for heater 2 with access doors in-place

under pressure depression tests

Flue

blockage

Test

chamber

pressure

in. w. c

Maximum

at

door

° F

Maximum

at

control

° F

Maximum

at

base

° F

0% neutral 158.4 109.9 92.7

-0.05 169.3 118.4 100.4

-0.1 170.1 147.4 102.2

-0.15 177.1 164.8 110.7

-0.2 264.6 229.5 116.1

-0.25 912.2 276.1 119.8

20% neutral 179.1 127.0 108.7

-0.05 182.8 142.2 110.5

-0.1 183.0 157.3 110.7

-0.15 221.0 178.2 116.2

-0.2 994.6 771.3 125.1

60% neutral 210.6 137.1 114.1

-0.05 206.4 163.8 113.7

-0.1 662.9 381.9 149.0

100% neutral 466.0 208.0 103.3

Table 5 Air temperature at heater door, control, and bas

for heater 2 with access doors not in-place

under pressure depression tests

Test Maximum Maximum Maximum

Flue chamber at at at

blockage pressure door control base

in.w.c. °F °F °F

0% neutral 322.3 176.9 104.5

-0.05 294.4 181.8 110.1

-0.1 280.9 147.9 113.0

-0.15 277.7 114.8 116.4

-0.2 741.9 930.9 126.0

-0.25 914.7 779.2 128.1

20% neutral 344.5 184.1 114.3

-0.05 327.4 185.5 115.9

-0.1 280.0 165.2 117.5

-0.15 349.5 141.6 121.8

-0.2 932.2 882.3 132.8

60%

100 %

24

(not tested)

(not tested)
With access doors not in-place, flow inverted or flame rolled out at

-0.2" water column for both no flue blockage and 20% blockage (figures 18

and 19). Flames could be seen outside access doors during both tests.

The temperature at the door registered over 900°F (table 5). Tests for

this heater were stopped after 20% blockage test. The heater control

valve was damaged and rendered useless by high temperature, even though

thermal shields were provided during the tests.

Inversions of flue flow at times were not definite. When the flue outlet

was partially blocked and the test chamber was under negative pressure,

the direction of flue flow appeared to become unstable. This was evidenced

by erratic flue temperature and carbon dioxide concentration at the

measurement points, as well as temperatures at door and control. However,

high air temperature at the door and other points, and visible flames

outside the heater assured flame roll-out. Unlike heater 1, the burner

fire did not extinguish after flue inversion. The burner was manually

turned off at the end of each test in order to protect the heater and

control from being damaged.

5.5 Heater 3 Results

a. Cyclic Test

There was no flame roll-out during cyclic tests with the doors in-place

(figure 20). With doors not in-place (figure 21), the temperature

momentarily reached over 320°F at -0.05" water column and over 270°F at

-0.1" water column. The burner kept on burning after ignition until it was

25
turned off manually at all test pressure levels. At the time of ignition

hot air spilled out from the access doors momentarily.

b. Chamber Pressure Depression Test

There was no flue inversion or flame roll-out during pressure depression

tests, except at 100% flue blockage with access doors off, when flames

were visibly seen outside of the heater jacket (figures 22 through 29).

With access doors in-place, the highest door temperature recorded in all

blockages was just under 250°F (table 6). With doors off, it reached

492°F at 100% flue blockages (table 7). It was interesting to note that

Table 6 Air temperature at heater door, control, and b,

for heater 3 with access doors in-pl ace

under pressure depression tests

Test Maximum Maximum Maximum

Flue chamber at at at

blockage pressure door control base

in. w. c°F °F °F

0% neutral 187.2 107.7 96.9

-0.05 178.2 104.4 96.6

-0.1 178.9 100.9 94.1

-0.15 156.7 95.5 93.0

-0.2 139.5 94.5 92.3

-0.25 137.1 93.7 91.6

20% neutral 200.3 112.5 97.2

-0.05 200.7 108.3 97.9

-0.1 200.7 105.1 95.2

-0.15 196.0 105.1 93.4

-0.2 152.1 96.8 93.0

-0.25 143.1 95.7 92.8

60% neutral 249.9 120.6 97.2

-0.05 244.9 119.8 95.2

-0.1 248.5 112.5 95.2

-0.15 240.1 111.2 95.4

-0.2 235.9 108.5 95.0

-0.25 235.9 105.4 95.0

100% neutral 213.3 131.7 84.2

26
Table 7 Air temperature at heater door, control, and base

for heater 3 with access doors not in-place

under pressure depression tests

Flue

blockage

Test

chamber

pressure

in. w. c

Maximum

at

door

°F

Maximum

at

control

°F

Maximum

at

base

°F

0% neutral 307..8 128. 7 95.,9

-0.05 317..7 129. 6 95.,9

-0.1 292.,3 125. 6 93.,4

-0.15 270.,1 122. 2 93.,0

-0.2 241..0 110.,8 92.,1

-0.25 183.,0 103.,5 91.,9

20% neutral 332..4 134.,1 95.,4

-0.05 363,.4 134.,2 95..5 -0.1 330.,8 131.,5 94.,1

-0.15 306,.7 126.,5 93..6 -0.2 257..0 113.,0 92.,8

-0.25 208,.4 107.,2 93..6

60% neutral 472..8 210.,2 98,,6

-0.05 471..6 207..3 96..3 -0.1 463,.3 214.,0 95..5 -0.15 424,.6 216.,9 94..6

-0.2 417..4 178.,0 94,.8

-0.25 395..1 160.,3 94,,1

100% neutral 491..9 533.,1 93..2

this heater showed lower temperatures at the door and control when higher

depression was applied.

At 100% flue blockage, the burner extinguished in less than 5 seconds

after the blockage was placed during the doors in-place test (figure 25)

When the doors were off (figure 29) , flames rolled out as soon as the

blockage was applied. The burner was turned off manually.

27
5 . 6 Heater 4 Results

a. Cyclic Test

This heater behaved much like heater 3 during cyclic tests (figures 30 and

31). When doors were off, 310°F hot air spilled momentarily over the door

opening at the time of burner ignition,

b. Chamber Pressure Depression Test

No flue inversion or flame roll-out occurred at 0% and 20% blockage in

both doors status (figures 32, 33, 36, and 37). Flue inversion took place

at 60% blockage and flames were visible outside the access door. With the

Table 8 Air temperature at heater door, control, and base

for heater 4 with access doors in-place

under pressure depression tests

Test Maximum Maximum Maximum

Flue chamber at at at

blockage pressure

in . w : c

door

° F

control

°F

base

° F

0% neutral 166. 3 109,.9 89,.1

-0.05 170,.6 108,,0 88,.7

-0.1 159.,6 110,.8 88,.2

-0.15 160,.9 112,.5 87,.3

-0.2 157.,5 116,.2 87,.6

-0.25 151,.7 115,.3 88,.5

20% neutral 175.,3 114 .6 88..9

-0.05 167..7 113,.0 88,.7

-0.1 168.,1 115,.9 87,.8

-0.15 168..6 117,.5 87,.6

-0.2 163.,6 117,.0 88,.2

-0.25 161..2 118..4 88,.9

60% neutral 180..1 117 .5 81,,1

-0.05 189,,9 120.,2 85,.5

-0.1 190. 9 132..4 86,.7

-0.15 206..2 150,,6 OO .4

-0.2 567,,9 558,.7 oo ,4

-0.25 974.,7 955,,8 88..0

100% neutral 259.,7 168..1 84..6

28
doors in place, inversion occurred at -0.2" water column (figure 34).

Without doors it occurred at -0.25" water column (figure 38). At 100%

flue blockage, fire rolled out when blockage was applied (figures 35 and

39). In all flame roll-out and flue inversion cases, the burner was

manually turned off. Tables 8 and 9 show the maximum temperature

recorded during doors in-place and not in-place tests. The temperature at

door and control reached above 950°F (60% blockage and -0.25" water

column) with doors in-place while it was about 400°F (100% blockage and

neutral pressure) with doors not in-place.

Table 9 Air temperature at heater door, control, and base

for heater 4 with access doors not in-place

under pressure depression tests

Flue

blockage

Test

chamber

pressure

in . w . c .

Maximum

at

door

°F

Maximum

at

control

°F

Maximum

at

base

° F

0% neutral 374..5 163,,2 92.,3

-0.05 395..6 166,,3 92..7 -0.1 383..2 158..4 91..8

-0.15 355..8 114..8 92..8

-0.2 357..3 110..5 92..7 -0.25 343,.9 109..6 92..8

20% neutral 364,,1 177..1 93..0

-0.05 372,.9 176..0 93..6

-0.1 373,.5 174,.6 93..9

-0.15 393,.4 129.,6 95..0

-0.2 424,.8 126,.5 94..6

-0.25 407,.7 134..6 94,.1

60% neutral 342..5 231..8 86..0

-0.05 316..2 247..5 90..1 -0.1 407..7 236,.3 91..6 -0.15 395..8 219..9 92..8 -0.2 376..9 168,.1 93..9

-0.25 355..1 142..9 92..7

100% neutral 399,.7 265..3 86..5

29
5 . 7 Heater 5 Results

a. Cyclic Test

Heater 5 was a LP-gas heater. It behaved differently during cyclic tests

from the other heaters in that flames rolled out continuously at certain

pressure depressions without flue blockage (figures 40 and 42). Therefore,

60% flue blockage tests were added to the cyclic tests (figures 41 and

43). Without flue blockage, door temperature exceeded 250°F at -0.2" water

column chamber pressure with doors in-place and at all pressure levels

with doors not in-place. With 60% blockage, flame rolled out and continued

to roll out at lesser pressure depression. Roll-out occurred at -0.15"

and -0.2" water column when access doors were in-place and at 0", -0.15",

and -0.2" water column when doors were off.

b. Chamber Pressure Depression Test

With access doors in place, flame roll-out did not appear without flue

blockage (figure 44). Roll-out occurred at all blockages even when

pressure depression was not applied (figures 45, 46, and 47). However, in

all occasions the burner extinguished within 30 seconds after flames

rolled out. With access doors off and 20% blockage (figure 49) , flames

rolled out intermittently at -0.15" and -0.2" water column chamber pressure

until the pressure was raised back to -0.05" water column when the burner

was extinguished by suffocation. At 60% and 100% blockage (figures 50 and

51), with the doors off, the burner fire extinguished within 42 seconds of

flame roll-out. The thermocouple output of the heater control was

monitored during the tests. No burner self-extinguishing was caused by

30
the heater control action. Tables 10 (doors in-place) and 11 (doors not

in-place) list the maximum temperature registered at the door, control,

and base of the heater for pressure depression tests.

Table 10 Air temperature at heater door, control, and base

for heater 5 with access doors in-place

under pressure depression tests

Flue

blockage

Test

chamber

pressure

in. w. c

Maximum

at

door

°F

Maximum

at

control

°F

Maximum

at

base

°F

0% neutral 146.8 107.4 93.2

-0.05 144.1 103.8 90.9

-0.1 136.2 102.4 92.1

-0.15 138.4 102.7 93.2

-0.2 151.5 104.9 93.2

-0.25 193.5 138.6 93.6

20% neutral 159.4 102.6 92.1

-0.05 146.5 103.6 90.3

-0.1 153.5 111.9 92.5

-0.15 218.7 150.8 95.5

-0.2 238.5 207.5 134.2

60% neutral 199.2 113.4 85.6

-0.05 356.0 203.9 85.6

-0.1 455.0 320.0 109.9

100% neutral 330.4 253.4 84.6

31
Table 11 Air temperature at heater door, control, and base

for heater 5 with access doors not in-place

under pressure depression tests

Test Maximum Maximum Maximum

Flue chamber at at at

blockage pressure door control base

in.w.c. °F °F ° F

0% neutral 349.7 197.6 96.1

-0.05 320.9 195.3 95.9

-0.1 340.3 185.7 96.3

-0.15 368.2 180.3 95.2

-0.2 404.2 139.3 95.0

-0.25 424.0 129.2 93.7

20% neutral 315.0 172.6 84.2

-0.05 388.2 318.6 145.8

-0.1 393.8 251.4 150.3

-0.15 350.2 215.2 152.2

-0.2 337.8 161.8 151.2

60% neutral 443.5 209.3 89.4

-0.05 514.9 303.3 93.9

-0.1 498.7 351.1 100.8

100% neutral 657.0 539.2 91.0

5.8 Summary of Test Results

5.8.1 Flue Inversion and Flame Roll-out

Tables 12 and 13 summarize the flue inversion and flame roll-out occasions

for the five water heaters. These tables show the levels of flue blockage

and chamber pressure depression when flame roll-out occurred. They also

indicate if the burner was self -extinguishing after flame roll-out

occurred, because a fire burning continuously after roll-out is considered

more dangerous than one which is self-extinguishing by suffocation. Also

shown is whether visible flames were observed during tests. However,

observation of flames may not be a reliable indication of flame roll-out,

since flame roll-out is sometimes intermittent and also may not be visible.

32
Table 12 Flame roll-out occurrences for cyclic tests

Doors in Place Doors Off

Heater

no

Flue

inversion

or flame

roll-out

Burner

selfextinct

(burner

Visible

flames

Flue Burner Visible

inversion self- flames

extinct

(burner

or flame

roll-out

(% block.

- in.w.c.

pressure)

on-time

seconds)

(% block.

- in.w.c.

pressure)

on-time

seconds)

1 0% - 0.1" Y (5) N 0% - 0.1" Y (7) N

0% - 0.15" Y (5) N 0% - 0.15" Y (5) N

0% - 0.2" Y (5) N 0% - 0.2" Y (6) N

2 0% - 0.15" Y (12) N 0% - 0.15" Y (14) Y

0% - 0.2" Y (6) N 0% - 0.2" Y (8) Y

3 (no r-o) N N 0% - 0.05" N N * 0% - 0.1" N N

4 (no r-o) N N 0% - 0" N N 'k 0% - 0.05" N N 'k 0% - 0.15" N N 'k 0% - 0.2" N N ~k

5 0% - 0.15" Y (6) N 0% - 0.1" Y (41) Y

0% - 0.2" N N 0% - 0.15" N Y

0% - 0.2" N Y

60% - 0" N Y

60% - 0.05" Y «5) Y 60% - 0.05" Y (32) Y

60% - 0.1" Y (46) Y 60% - 0.1" Y (71) Y

60% - 0.15" N N 60% - 0.15" N N

60% - 0.2" N N 60% - 0.2" N N

Y = yes

N = no

* = Temperature exceeded 250°F momentarily at access doors

the moment of burner ignition

Table 13 clearly indicates that the combination of flue blockage and

pressure depression accelerated flue inversion and flame roll-out. When

more flue blockage was applied, less pressure depression was needed to

33
induce flame roll-out. In several cases, only -0.1" water column pressure

was enough to have flame roll-out when heater flues were blocked 20 or

60%. Therefore, pressure depression is an important factor in flame

roll-out. With a few exceptions, door status (in-place or not in-place) also

Table 13 Flame roll-out occurrences for pressure depression tests

Doors in Place Doors Off

Heater Flue

no. inversion

or flame

roll-out

(% block.

- in.w.c.

pressure)

Burner Visible

self- flames

extinct

(burner

on-time

seconds)

Flue

inversion

or flame

roll-out

(% block.

- in.w.c.

pressure)

Burner Visible

self- flames

extinct

(burner

on-time

seconds)

0% - 0.15" Y «5) N 0% - 0.15" Y (15) Y

20% - 0.1" Y «5) N 20% - 0.1" Y (15) Y

60% - 0.1" Y «5) N 60% - 0.1" Y (5) Y

100% - 0" Y (90) N 100% - 0" Y

0% - 0.25" N Y 0% - 0.2" N Y

20% - 0.2" N Y 20% - 0.2" N Y

60% - 0.1" N Y

100% - 0" N N

0% (no r-o) N N 0% - 0" N N

20% (no r-o) N N 20% - 0" N N

60% (no r-o) N N 60% - 0" N N

100% (no r-o) Y «5) N 100% - 0" N Y

0% (no r-o) N N 0% - 0" N N

20% (no r-o) N N 20% - 0" N N

60% - 0.2" N Y 60% - 0.25" N Y

100% - 0" N N 100% - 0" N Y

0% (no r-o) N N 0% - 0" N N

20% - 0" Y (20) N 20% - 0.15" N Y

60% - 0" Y (30) Y 60% - 0.1" Y (42) Y

100% - 0" Y «5) Y 100% - 0" Y «5) Y

Y = yes

N = no

34
influenced flame roll-out greatly. It took less pressure depression to

induce flame roll-out or flames rolled out for longer periods of time

before extinguishing with access doors not in-place than with doors in-place.

Comparing cyclic tests with pure pressure depression tests for the same

heater and flue blockage, a majority of cases showed that flame roll-out

occurred at less pressure depression under cyclic conditions than under

pure depression conditions. However, with the exception of heater 5,

burners all extinguished within a short time after ignition during cyclic

tests

5.8.2 Flame Roll-out and Hot Air Spillage

Tables 2 through 11 show that hot air spillage from the heater base does

not appear to be a significant problem. It is also clear that, except for

a very few instances, the temperature of hot air spillage and flame

roll-out were much more severe with access doors not in-place than with

them in-place. Table 14 tabulates the results of all pressure depression

tests with and without the access doors in place. A measured temperature

outside the access doors of 250°F or higher is indicated by a "Y" in the

appropriate column. With doors in-place, heater 1 exceeded 250°F at 100%

flue blockage, heater 3 did not exceed this criterion under any of the

test conditions. With doors off, heater 1 failed this criterion when

flue blockage was at 20% and over. The other heaters failed in all flue

blockage tests including no blockage cases. Heaters 1 and 3 had less

flame roll-out than the other heaters and heater 2 had flame roll-out more

severe than the others

35
Table 14 Results of pressure depression tests

using a criterion of 250°F outside the access doors

for hot gas spillage

Flue Chamber

blockage Pressure

(%) (in.w.c.)

Doors

in-place

Doors

off

0 neutral N N

-0.05 N N

-0.1 N N

-0.15 N N

20 neutral N N

-0.05 N N

-0.1 N N

-0.15 N Y

-0.2 N Y

60 neutral N Y

-0.05 N Y

-0.1 N Y

100 neutral Y Y

0 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 Y Y

-0.25 Y Y

20 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 Y Y

60 neutral N (not tested)

-0.05 N (not tested)

-0.1 Y (not tested)

100 neutral Y (not tested)

0 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

-0.25 N N

20 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

-0.25 N N

Symbols: Y = over 250°F

N = not over 250°F

36
Table 14 Results of pressure depression tests

using a criterion of 250°F outside the access doors

for hot gas spillage (continued)

Heater Flue Chamber Doors Doors

blockage

(%)

Pressure

(in. w. c .

in-place o:

60 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

-0.25 N Y

100 neutral N Y

0 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

-0.25 N Y

20 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

-0.25 N Y

60 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 Y Y

-0.25 Y Y

100 neutral Y Y

0 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

-0.25 N Y

20 neutral N Y

-0.05 N Y

-0.1 N Y

-0.15 N Y

-0.2 N Y

60 neutral N Y

-0.05 Y Y

-0.1 Y Y

100 neutral Y Y

Symbols: Y = over 250°F

N = not over 250 °F

37
Flame roll-out results at neutral chamber pressure are of particular interest,

since these test conditions satisfied the test requirements of the proposed

revisions to the ANSI standard. With doors in-place, the door or control

temperature of heaters 1, 2, 4, and 5 exceeded 250°F only when 100 % flue-blockage were applied. However, when the access doors were removed,

16 of the 18 neutral pressure cases in table 14 exceeded this temperature

limit. More discussion of these results and the proposed ANSI test method

is given in the next section.

Although the investigation of how water heater construction effect flame

roll-out is beyond the scope of this study, no-blockage tests were

performed under chamber pressure depression on heater 3 with the draft

hood from heater 2. Quite contrasting results were observed. As described

previously, heater 3 had the least tendency for flame roll-out and its

draft hood appeared to be substantially better constructed than the draft

hoods of the other four heaters. With access doors off and with its own

draft hood, the flame was not observed outside the access door until 100%

flue blockage was applied (see table 13 and discussion in paragraph 5.4).

However, with heater 2's draft hood in place on heater 3, flame roll-out

was clearly observed during pressure depression tests even without any

blockage. This experiment demonstrated that draft hood design affected

stack downdraft and water heater performance substantially. Both the ANSI

standards on water heaters [3] and draft hoods [5] require that "draft

hood shall not extinguish the main burner flames nor cause them to flash

back, lift, float, burn outside the water heater", when a total downdraft

pressure ranging from zero to 0.05" water column is imposed at the outlet

38
of the draft hood. It was quite clear from the tests that one draft hood

resisted downdrafts of more than 0.05" water column much better than other

draft hoods

5.8.3 Comparison with Proposed ANSI Test Method

The proposed ANSI test procedure requires that the heater be tested under

neutral pressure and its flue be blocked at 20% increments until it is

entirely blocked off. At no time during this test shall flames issue

outside the face of the jacket. If a unit can not meet this requirement,

a safety device must be provided to cut off gas to the burner during the

blockage test. The proposed standard revisions do not specify the kind of

devices to be used. Presumably, the water heater manufacturers may use

temperature, pressure, or other means to sense flue blockage and activate

the gas cut off action.

None of the heaters tested in this study were equipped with safety devices

to conform to the proposed standard revisions, and thus no conclusion can

be made as to whether the inclusion of such safety devices would allow for

the compliance of these heaters with the proposed revisions to the ANSI

standard. However, for the heaters tested, comparisons of the proposed

ANSI test method (flue blockage without pressure depression) with the tests

performed in this study, combination of flue blockage, pressure depression,

and door status, may be made*.

* Under the chamber pressure depression test of this study, the

proposed ANSI test method was actually performed when various flue

blockages were applied with neutral chamber pressure.

39
Although the proposed ANSI test procedures do not specifically state

whether the access doors are in-place or not in-place during tests,

judging from other required tests in the gas water heater standard (ANSI

Z21.10.1), it was presumed that all tests are intended to be conducted

with doors in-place. Based on this assumption and a criterion of 250°F

hot air spillage temperature being a indication of flame roll-out, table

15 was constructed to compare the results of the proposed ANSI test method

(flue blockage only) and other tests conducted in this study. All

heaters, except heater 5, satisfied the ANSI proposed requirements for no visible flame roll-out and would not need for additional safety devices.

However, if 250°F air temperature outside the access doors is also added

as a criterion of flame roll-out, then only heater 3 did not have flame

roll-out. Heater 3 also satisfied the above temperature criterion for no

flame roll-out during the combined flue blockage/pressure depression tests

with access doors in-place. However, it failed the pressure depression tests

with the doors off. Thus, in order to protect home owners who leave the

water heater access doors open, the CPSC and the ANSI water heater

standards subcommittee should consider requiring that either water heaters

be provided with a means to assure that the access doors are closed properly

during operation (e.g. interlocking devices) and/or the units be tested

both with doors in-place and doors removed. The former requirement should

be considered by CPSC and the ANSI subcommittee in combination with a possible

additional requirement that water heaters be also equipped with piezoelectric

ignition systems in order to alleviate the necessity of opening the access

doors by the home owners to light the burners.

40
Table 15 Comparison of proposed ANSI test and

pressure depression test results

Heater

no

Combination flue blockage

Flue blockage only and pressure depression

ANSI method & 250°F

ANSI

method

ANSI method

and 250 °F

Doors in- Doors not

place in-place

1 no roll-out roll-out

2 no roll-out roll-out

roll-out roll-out

roll-out roll-out

no roll-out roll-out

roll-out roll-out

roll-out roll-out

3

no roll-out no roll-out

4 no roll-out roll-out

5 roll-out roll-out

In addition, it has also been demonstrated that flame roll-out can occur

either under negative pressure or at partial flue blockage with negative

pressure. Not knowing the kind of safety devices heater manufacturers

will provide to satisfy the proposed ANSI revisions, these devices may

well satisfy the blocked flue tests under neutral pressure, yet fail to

work properly under depressurization conditions or situations combining

partial flue blockage and depressurization.

41
REFERENCES

1. Interagency Agreement between the National Bureau of Standards and

the U.S. Consumer Product Safety Commission on Flame Roll-out Test for Gas

Fired Water Heaters, (September, 1986).

2. Adams, D.E., and Morphy, C.C., "Testing of Gas Fired Water Heaters

and Water Heater Combination Control Valves", Calspan Corporation,

(September, 1985).

3. American National Standard Institute, Inc., "American National

Standard for Gas Water Heaters, Volume I, Automatic Storage Water Heaters

With Inputs of 75,000 Btu Per Hour or Less", Secretariat American Gas

Association, ANSI Z21.10.1, (1984).

4. American National Standard Institute, Inc., "Draft text for review

and comment on Proposed Revisions to American National Standard for Gas

Water Heaters, Volume I, Storage Water Heaters with Input Ratings of

75,000 Btu Per Hour or Less", (January, 1987)

5. American National Standard Institute, Inc., "American National

Standard for Draft Hoods", Secretariat American Gas Association, ANSI

Z21.12, (1981).

6. Switzer, D., "Final Report on ES Water Heater Contract", U.S.

Consumer Product Safety Commission, (September, 1985).

7. Moffatt, S., "Backdrafting Woes" , Progressive Builder, (December, 1986).

8. TRW Energy Systems Group, "Combustion Guidelines for Single and

Multifamily Dwellings", American Gas Association, (1980).

42
TEMPERATURE:

T1 - vent stack

T2 — dra-ft hood

T3 — flue top

T4 - flue bottom

Test

*P3

chamber

Figure 1 Schematic diagram showing sensor locations for

temperature, pressure, and gas concentration

43
TEWPERAUiRE,

F

TEMPERATURE,

F

FRESSURE,

INCH

W.C.

Figure 2 Cyclic test, access doors in-place — Heater no

44
TEMPERATURE AT FLUE eSc PILOT LIGHT

(3) TEMPERATURE AT STACK &

DRAFT MOOD

BE

<L> eo_H

£

&ocvj OC_P

O 20 AO SO 30

Tl ME, MINUTE

Figure 2 Cyclic test, access doors in place Heater no. 1

45
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

£ 1 > OF AM BER PRESSURE Sc FLU E DRAr

1 30 £ 3 > TEMP. AT COMTROU Sc HEATER BOTTOM

a CONTROL TIME. MIMUTE BOTTOM U

SO

Figure 3 Cyclic test, access doors off — Heater no. 1

46
C02

COJCEMTRAUQN,

PER

CE>JT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands.)

1 .2

<A> TEM PERATU RE AT FLUE eSc PILOT LIGHT

O 20

FLUE TOP

-4-0 TIME, MINUTE FLUE BOT

SO SO

P I LOT

(5> TEMPERATURE AT STACK <3c DRAFT HOOD

bTACK TIME. Ml MUTE DRAFT HOOD

O 20 AO SO SO

TIME. Ml MUTE

Figure 3 Cyclic test, access doors off — Heater no- 1

47

A
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

< 1 > CHAMBER PRESSURE <24 FLUE: DRAFT

700

600

500

400

300

2 0 0

1 OO

o

O A B 12 1© 20 24- 20

time. minute

1 -+- 2 o 3 A

<2> TEM RE RATU R E AT AGO ESS DOOR

1 50

1 AO

1 30

1 20

1 1 O

1 OO

90

SO

70

SO

50

Figure 4 Pressure test, access doors in—place, no flue blockage — Heater no. 1

(,3) TEM R _ AT OO NT ROI <Sc HEATER BOTTOM

TIME. MINUTE

a CONTROL -+- BOTTOM L_ BOTTOM R

43
CD2

CONCEPTION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

C-O TEMPERATURE AT FLUE «5c PILOT LIGHT

Figure 4 Pressure test, access doors in place, no -flue blockage — Heater no. 1

49
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

CHAM BER PRESSURE: «&c FLU E DRAFT

1 30

1 -4-0

1 30

1 20

1 1 O

1 OO

30

©O

70

SO

50

Figure 5 Pressure test, access doors in—place, 20% -flue blockage — Heater no. 1

(3 } TEN/1 R. AT CONTROL <£c M EATER BOTTOM

TIME. Ml MUTE

a CONTROL •+ BOTTOM L ^ BOTTOM R

50
<A> TEM PERATU RE AT EL.LJE «Sc PILOT LIGHT

a

£

<S> TEMPERATU R E AT STACK «Sc DRAFT MOOD

STACK MINUTE DRAFT HOOD

3o

CtL LlJ Q_

§f=

lD§c

t-vi QO

Figure 5 Pressure test, — Heater

access doors in place,

no- 1 20% flue blockage

51
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

iWCH

W.(

(2) TEMPERATURE AT AC CESS D O Q R

1 SO

1 AC

1 30

1 CO

TIC

1 OO

90

ao

TO

so

£50

o A a 1 C 1© 20 24 26

TIME, MINUTE „

a CONTROL. BOTTOM L BOTTOM R

Figure 6 Pressure test, access doors in—place, 6071 -flue blockage — Heater no. 1

(3> TEM R - AT CONTROL 3c HEATER BOTTOM

52
CD2

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Ttousonds)

Figure 6 Pressure test, — Heater

access doors in place,

no. 1 60X flue blockage

53
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

a. a

< 1 > CHAMBER PRESSU RE <Sc FLUE DRAFT

0.3 —

0.2 - -BLOCKAGE IN PLACE

FLAME ROLL-OUT

CHAMBER RRESS. C~

TIME. MINUTE FLUE DRAFT X TO

TIME. MINUTE

o CONTROL- BOTTOM U o BOTTOM R

Figure 7 Pressure test, access — Heater no- i doors in—place, 1007. t i ue

54
(sptjosnoi.il)

'luTiW'in

JWTi

i

'iviniuvn.iiMii

imt\

'j:ij,

hiniiw\iiKmm'\

7^

CA> TEMPERATURE AT FLUE Sc PILOT l_!OMT

(5) TEM PERATU RE AT STACK Sc D RAFT MOOD

r igure 7 Pressure test, access doors in place, 1007- -flue blockage — Heater no- 1

55
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

TIME* MINUTE a CHAMBER PRESS* < — >

•+ FLUE DRAFT X 1 O

TIME, MINUTE

cd CONTROL -+- BOTTOM l_ ^ BOTTOM R

Figure 8 Pressure test, — Heater

access doors o-f-f , no. 1 no flue blockage

56
C02

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

( TEMPERATURE: AT FLUE <Sc pilot light

TEMPERATURE AT STACK c3c DRART MOOD

Figure 8 Pressure test, access doors off, no flue blockage — Heater no. 1

57
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE.

INCH

W.C.

1 so

1 -4-0

1 30

1 OO

1 1 O

1 OO

SO

BO

TO

BO

2-0

Figure 9 Pressure test, access doors o-f-f , 207. -flue blockage — Heater no. 1

(3) TEMP. AT CONTROL Sc HEATER BOTTOM

TIME. MINUTE

a CONTROL -+- BOTTOM l_ o BOTTOM R

58
C02 C

ONCEIsfTRATlON

,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

< -O TEMPERATURE AT FLUE <Sc PILOT LIGHT

TIME, Ml MUTE a FLUE TOR -+ FLUE BOT o Rl

(3) TEMPERATURE AT STACK DRAFT HOOD

STACK Ml MUTE

D RAPT HOOD

T 3

1 A

T 3

1 O

1 T

1 O

5

S

7

S

5

A

3

2

1o

Figure 9 Pressure test, access doors off, 20% -flue blockage — Heater no- 1

(6) COO AT TOP OF FLUE PIPE

TIME, MIMUTE

59
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

IMCH

W.C.

Cl'j CHAMBER PRESSURE! Sc FLU E DRAFT

<3) TEMP. AT OOMTROL- Sc. HEATER BOTTOM

Figure 10 Pressure test, access doors off, 607. flue blockage — Heater no. 1
C02

CONCENTRATION.

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

<a> temperature: at flue Sc pilot light

<S5> TEMPERATURE AT 5TAC K Sc. drart mood

STACK Ml MUTE DRAFT HOOD

Figure 10 Pressure test, access doors off, 60“/. flue blockage — Heater no. 1

61
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

TIMET, MINUTE

a CONTROL BOTTOM L. BOTTOM R

Figure 11 Pressure test, access doors o-f-f , 1007. flue blockage — Heater no. 1

62
es o &«£

§c_-> sa_S’5

u3

S-2 ec_j

2 1 S

TIME. MINUTE

Figure 11 Pressure test, access doors off, 100% flue blockage — Heater no. 1

63
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C,

<3> TEMP. AT OO NTRQL &. M EATER BOTTOM

Figure 12 Cyclic test, access doors in-place — Heater no.

64
<A> TEMPERATURE AT FLUE <3c PILOT LIGHT

C±J

<LA etc

Li_l D_5f=a

<LA

c~-J OC_>

O 2 0 AO SO SO

TIME. MINUTE

Figure 12 Cyclic test, access doors in place — Heater no. 2

65
TEMPERATURE,

F

TEMPERATURE,

F

FRESSURE,

INCH

W.C.

Figure 13 Cyclic test, access doors off — Heater no. 2

66
CrZ t=>

-=z: o-j Pn o

9sjS. a—

TEM F? E: RATU RE AT FLUE &z PILOT LIGHT

i±3

CJ> cc

Li_i a.

gS

CVJ CO

C_?

20 AO

MINUTE

Figure 13 Cyclic test, access doors off — Heater no. 2

67
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

a. a

< 1 } OHAW BCR PRESSURE: =Sl: FLU E DRAFT

0.3

0.2

O. 1

o — a. i — 0.2

O A B 12 1© 20 24- 26

Tl ME, MINUTE o CHAMBER PRESS. ( — >

-+- FLUE DRAFT X 10

C 2 } TEMPERATURE AT ACCESS DOOR

O.S

O.Q

O.T' 0.6

O.S

O.A

0.3

a.

O. 1 O A e 12 1© 20 2 A 28

TIME. MIMUTE

1 A-2 O 3 A. A

: STACK INVERTED FLUE INVERTED

?*P3Bg»ac»e<B<BC

i 1 1 1 1 1 1— 1 1 1 1 1 1 r

<3> TEMP. AT CONTROL. <Sc HEATER BOTTOM

TIME. MINUTE

a CONTROL a- BOTTOM L *> BOTTOM R

Figure 14 Pressure test, access doors in-place, no flue blockage — Heater no. 2

68
0)2

CCNCENTRAT10N,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thou&ondsj

C-O TEM PERATU F»E AT f-L_l_JE £c PILOT LIGHT

TIME. MINUTE

o STACK + DRAFT HOOD

Figure 14 Pressure test, access doors in place, no -flue blockage — Heater no. 2

69
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

(Thousands')

TIME, (VI I mute: CHAMBER PRESS. < — > FLUE DRAFT X IQ

C 2> TEMRERATURE AT ACCESS DOOR

<3 > TEM F* . AT CONTROL &c HEATER BOTTOM

TIME, MINUTE

a CONTROL BOTTOM L BOTTOM R

Figure 15 Pressure test, access doors in—place, 20V- -flue blockage — Heater no. 2

70
temperature: AT FLUE &z pilot light

TIME, Ml MUTE

o FLUE TOP -+ FLUE SOT o PILOT

<S> TEMPERATURE AT STACK Sc DRAFT MOOD

GO

cj> cnLU

CL. s

n

£5

cvi OO

Figure 15 Pressure test, access doors in place, 20V. -flue blockage — Heater no- 2

71
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

( 1 ) CHAMBER PRE^IURE FLUE DRAF r —-BLOCKAGE IN PLACE : FLUE INVERTED

0.2 - STACK INVERTED—

—BURNER DOWN MANUALLY

O. 1 -

i—»—•—i—»-

1 POBg-CHCK-} E3 O' B"E3E3g>t3g30EaP

r

•Q&fetBea

— 0.1 -

o

a CHAMBER PRESS. C — >

1 2

Tl Mt

T

1 s MINUTE

20 2A

FLUE DRAFT X 10

<2> temperature: at ago ess door

<3> TEMP. AT CONTROL Sc HEATER BOTTOM

Figure i6 Pressure test, access doors in-place, 607. flue blockage — Heater no. 2

72
1 . 4- (A> TEMPERATURE AT ELUE <Sc PILOT LIGHT

LI co QL -s

co S o

£

R

li- es

<'5> TEMPERATURE AT STACK <Sc ORART HOOD

C3 U>sCL

so

rxl OC_3

Figure 16 Pressure test, access doors in place, 60% -flue blockagi — Heater no. 2

73
<1> CHAMBER PRESSURE «Sc FLU E DRAFT

C>

3BP LC

)£

&

&

g

<3> TEMP. AT CO NT RQI cS<: HEATER BOTTOM

£

g

CONTROL TIME. MINUTE BOTTOM L. BOTTOM R

Figure 17 Pressure test, access doors in—place, 100% -flue blockage — Heater no. 2

74
C02

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

-\ .A

<]A> TEMPERATU RE AT FLUE <&: PILOT LIGHT

1 2 1 6 20

FLUE TOP TIME. MINUTE FLUE BOT

2-4-PI 2©

1 3

1 A

1 3

1 2

1 1

1 O

sa7

S

5

A

3

To

Figure 17 Pressure test, access doors in place, 1007. -flue blockage — Heater no. 2

(6) 002 AT TOP OF" FLUE PIPE

75
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

*.(

(Thousands)

(Thousands)

< 2 > TEMPERATURE AT ACC ESS DOOR

Figure 18 Pressure test, access doors off, no flue blockage — Heater no. 2

- - 7A
C02

CONCENTRATION,

PER

CENT

TEMPERATl'RE,

F

TEMPERATURE,

F

Figure 18 Pressure test, access doors oft, no flue blockage — Heater no- 2

77
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

(Hiousondsj

( 1 ) CHAMBER PRESSURE! FLUE DRAFT

Figure 19 Pressure test, access doors off, 2.QV. -flue blockage — Heater no. 2

78
C02

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

C-4-> TEMPERATURE AT FLUE «Sc PILOT LIGHT

Figure 19 Pressure test, access doors of -f , 20V. flue blockage — Heater no. 2

79
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

Figure 20 Cyclic test, access doors in-place — Heater no. 3

80
g= s

S I “=(!= cs w

20

FLUE TOP TIME, Ml mute: FLUE SOT pilot

£

g

Q_lS

t±3

CJ> Q£LU

Q_

a

io

Figure 20 Cyclic test., access doors in place — Heater no. 3

81
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

Figure 21 Cyclic test, access doors off — Heater no. 3

82
O 20 -4-0 SO 30

a FLUE TOP TIME, MINUTE FLUE BOT o P I LOT

£±3

CJ> es

a_

Figure 21 Cyclic test, access doors off Heater no- 3

83
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

!_ — I 1 1 1 O 2 0 *4-0 so

time:, minute

q CHAMBER PRESS. C. — > FLUE DRAFT X in

O 20 AO oO

TIME, Ml MUTE

o CONTROL BOTTOM t_ » BOTTOM R

Figure 22 Pressure test, access doors in-place, no flue blockage — Heater no- 3

84
002

CCMEITf

RATION,

PER

CENT

TEMPERATURE.

F

TEMPERATURE,

F

(a> temperature: AT FLUE <Si pilot liomt

O 2 0 AO *=>’-) TIME, Ml MUTE

a STACK + DRAFT HOOD

(6) COO AT TOP OF" FLU E PIPE

Figure 22 Pressure test, access doors in place, no -flue blockage — Heater no- 3

85
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

(1) CHAMBER PRESSURE Sc FLU E DRAFT

TIME. MINUTE

a CONTROL- BOTTOM l_ o BOTTOM R

Figure 23 Pressure test, access doors in—place, 207. flue blockage — Heater no. 3

86
5= §

c_> S

Q_

2

lD

TIME. MINUTE

Figure 23 Pressure test, access doors in place, 20% flue blockage — Heater no- 3

87
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

< 1 } CHAMBER PRESSURE; <3c. El_UE DRAFT

TIME. MINUTE

o CONTROL BOTTOM L. o BOTTOM R

Figure ^.4 Pressure test, access doors in—place, 60V. flue blockage — Heater no. 3

88
C02

COt'JCENTRAnOT'J,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(ThouBondsJ

1 . s

<A> tem peratu RE AT FLUE «Sc pilot light

1 .5 -=

1 -A — 1.3-

1 * 2 -

1*1 -

1 - 0*9 - 0*3

0*T

o.s - 0.5 -

O

20 AO 0 O

FLUE TOP TIME, MINUTE FLUE BOT PILOT

O 2 0 AO fc=Lj TIME. MINU TE

Figure 24 Pressure test, access doors in place, 607. flue blockage — Heater no. 3

89
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

( 1 } C MAN/1 QER PRESSURE <£c ELUE DRAFT

C) TEMPERATURE AT ACCESS DOOR

Figure 25 access

T

Pressure test, — Heater no

90

doors in—place. 100/C flue blockage
a®

£3

CdLU

Q_

s

r--j c_>

O 20 *4-0 60

TIME, MINUTE

Figure 25 Pressure test, access doors in place, — Heater no- 3

100X -flue blockage

91
a. -4-

<; 1 > CHAMBER PRESSURE F~L_U E DRAFT

&

0.33 - 0*3 - a .23 -

< STACK INVERTED

STACK REVERTED >

ct: g

£

<3> TEMP. AT OO NTROL «3c HEATER BOTTOM

£

£

CONTROL TIME. MINUTE BOTTOM L B OTTO M R

Figure 26 Pressure test, access doors o-f-f , no -flue blockage — Heater no. 3

92
<5> TEM PERATU RE ACT STACK Sc DRAFT MOOD

cj> So_

i=

S

r-J

!_J U-'

O 20 -4-0 SO

TIME, Ml MUTE

Figure 26 Pressure test, access doors o-ff — Heater no- 3

no -flue blockage

93
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

< 1 > CHAMBER PRESSURE «3c RUUE DRAFT

(2) TEMPERATURE AT ACCESS OOOR

TEMP. AT CO NTR O I <Sc HEATER BOTTOM

TIME. MINUTE

o CONTROL BOTTOM L o BOTTOM R

Figure 27 Pressure test, access doors of f , 207. flue blockage — Heater no. 3

94
£

Fp

time:, minute

a STACK DRAFT HOOD

time:, minute

t x ijui c

95
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

. -4- < T j CHAMBER P RES SURE! «3c FLUE DRAFT

TIMET. MINUTE

a CONTROL. h- BOTTOM L o BOTTOM R

Figure 28 Pressure test, access, doors of -f , 60V. flue blockage — Heater no. 3

96
CQ2

CONCENTRATION.

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

TEM P1 E RATU RE AT FLUE PILOT L.IGMT

Figure 28 Pressure test, access doors off, 60% flue blockage — Heater no. 3

97
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

a.-+ <1> CHAW BER PRESSURE Sc FLU E DRAF

O.J5 - 0.3 - 0.25 - 0.2 - 0 . T S -

< -BLOCKAGE IN PLACE

FLAME ROLL-OUT

o .os - 0 -VVH-—

20

CHAMBER PRESS. ( — > TIME. MIMUTE

-1-0 FLUE DRAFT X.IO

(3> TEMP. AT OO NTROI <&z M EATER BOTTOM

TIME, MIMUTE

a CONTROL -+• BOTTOM U a BOTTOM R

Figure 29 Pressure test, access doors o-f-f , 100’X. -flue blockage — Heater no. 3

98
C02

COCEMfWIGN,

PER

CE>JT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

<.'55> TEMPERATURE AT STACK DRAFT H QO O

TIME, MINUTE

Figure 29 Pressure test, access doors off, 1007. -flue blockage — Heater no. 3

99
TEMPERATURE,

F

TEWPERATI.IRE.

F

PRESSURE,

INCH

W.C,

< 1 } OMAN/1 BER PRESSURE &c. FT U E DRAFT

Figure oQ Cyclic test, access doors in—place — Heater no. 4

100
£

l3 v

£c_> QCLU

Q_s

80

cvj 01

CS) 002 AT TOR OF" FLUE RIRE

Figure 3u Cyclic test, access doors in place — Heater no. 4

101
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

< 1 > CHAMBER PRESSURE FLUE DRAFT

Figure 31 Cyclic test, access doors o-f-f — Heater no. 4

102
CO2

CONCENTRATION,

PER

CEJ'JT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

O 2D 40 50 SO

TIME, minute:

Figure 31 Cyclic test, access doors o-f-f — Heater no. 4

103
TEMPERATURE.

F

TEMPERATURE,

F

FRE55URE,

INCH

W.C.

Q--4-

( 1 ) CHAMBER PRESSURE: &c. FLUE PR^FT

0-3S3 - 0-3 -

< STACK INVERTED STACK REVERTED >

TIME, Ml MUTE

a CONTROL -+ BOTTOM L o BOTTOM R

Figure 32 Pressure test, access doors in-place, — Heater no- 4

no flue blockage

104
C02

CONCENIWION,

PER

CEJMT

TEMPERATURE,

F

TEMPERATURE,

F

(Thcusonds)

Figure 32 Pressure test, access doors in place, no flue blockage — Heater no. 4

105
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

IfCH

W.C.

(‘T> CHAMBER PRESSURE FLU E DRAFT

( 2 > TEMPERATURE AT ACOESS EQOR

TIME. MINUTE <=> CONTROL BOTTOM L. o BOTTOM R

Figure 33 Pressure test, access doors in-place, 2. 07. flue blockage — Heater no. 4

106
C02

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

TIN/IE. MINUTE

Figure 33 Pressure test, access doors in — Heater no. 4

place, 2. 0"/. -flue blockage

107
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

(Thousands)

(Thousands!

a. a

< 1 } CHAMBER PRESSURE: FLU E DRAFT

<S> TEMPERATURE AT ACCESS DOOR

(3 ) TEMP. AT CONTROL. =Sc M EATER BOTTOM

TIME. MINUTE a CONTROL. + BOTTOM U o BOTTOM R

Figure 34 Pressure test, access doors in-place, 607. -flue blockage — Heater no. 4

108
-=r oo £ §

9=£=

e

£±3 c_> oc

LlJ a_

fc; s

Figure 34 Pressure test — Heater

? access doors in place,

no. 4

607. flue blockage

109
TEMPERATURE,

F

TEMPERATURE,

F

FRE5SURE,

INCH

W.C.

O 20 *4-0 6Q

TIME, MINUTE n CHAMBER PRESS. C~ > FLUE DRAFT X . 1 O

time, mi mute

a CONTROL- •+• BOTTOM L_ o BOTTOM R

Figure 35 Pressure test, access doors in—place, 1007. -flue blockage —- Heater no. 4

110
:Q2

concentration,

per

cent

TEMPERATURE,

F

TEMPERATURE,

f

(Thousands)

R

i

TEMPERATURE AT FLUE Sc. PILOT LIGHT

Figure 35 Pressure test, access doors in place, 1007. -flue blockage — Heater no. 4

111
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

( 3 > TEW R . AT CONTROL. Sc M EATER BOTTOM

TIME. MINUTE CONTROL. -+- BOTTOM l_ o. BOTTOM R

Figure 36 Pressure test, access doors o-f -f , no flue blockage — Heater no. 4

112
(A} TEMPERATURE AT FLUE <Sc PILOT LIGHT

TIME, MINUTE

a FLUE TOR FLUE BOT o PILOT

sL>

OC

U_l a_

«5

<o

Figure 36 Pressure test, access doors o-f-f — , Heater no. 4

no -flue blockage

113
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

<; 1 > CHAMBER PRESSURE! Sc FLUE DRAFT


 temperature: at access cdoor

TIME. MINUTE

a CONTROL. + BOTTOM L o BOTTOM R

Figure 37 Pressure test, access doors off , 20% -flue blockage — Heater no. 4

i

114
.1

< 3 > TEMPERATl_l R EE AT STACK <3c DRAFT H OO O

QC

s

Q_a

STAOK MINUTE

DRAFT- HOOD

Figure 37 Pressure test., access doors o-f-f

— Heater no. 4

207. -flue blockage

115
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.(

0 .-4- < 1 } CHAMBER PRESSURE «Sc F~I_U El DRAFT

TIME. MINUTE

a CONTROL + BOTTOM l_ o BOTTOM R

Figure 3B Pressure test, access — Heater no. 4

doors off, 60'/. flue blockage

116
O 20 -4.0 SO

TIME, MINUTE

a STACK DRAFT HOOD

Figure 38 Pressure test, access doors o-f-f , 60V. flue blockage — Heater no- 4

117
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

O 20 -4-0 SO

TIME. MINUTE a CHAMBER PRESS- ( — > a- FLUE DRAFT X 1 C>

TIME. M I M U TE

a CONTROL -t- BOTTOM i_ -=» BOTTOM R

Figure 39 Pressure test, access doors of -f , lOO^L -flue blockage — Heater no. 4

118
C02

COJCENTRAnOfi

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands’)

2. T (a> temperature: at flue «&= pilot light

Figure 39 Pressure test, access doors o-f-f , 100% -flue blockage — Heater no. 4

119
TEMPERATURE,

F

TEMPERATURE,

F

FRESSURE,

INCH

W.C.

; 1 } CHAMBER PRESSURE FLUE DRAFT

CHAMBER PRESS. }

TIME, Ml MUTE

-t- FLUE DR-F . i O

Tl ME, MINUTE

a CONTROL +• BOTTOM U ^ BOTTOM R

Figure 40 Cyclic test, access doors — Heater no. 5

i n—pi ace

,

no -flue blockage

120
coz

ccncentrTM,

per

cmr

temperature,

f

temperature,

f

(Thousands)

<A> TEM P1 E RATU R E AT FLUE Sc PILOT LIGHT

<S> TEM PERATU RE AT STACK Sc DRAFT MOOD

20 AO

TIME, Ml MUTE

SO

igure 40 Cyclic test, access door — Heater no, 5

in pi =ce

no 1 1 ijp b 1 oc kaqe

121
TEMPERATURE,

F

.

TEMPERfflURE,

F

PRESSURE,

INCH

W.C.

0.22 { 1 2> CHAMBER PRESSURE <Sc FLUE DRAFT

<2> TEMPERATURE AT ACCESS DOOR 300

450

400

350

300

230

200

1 30

1 oo

TIME, MINUTE

n 1 -+- 2 o 3 a A

TIME, MINUTE a CONTROL -+- BOTTOM L_ ^ BOTTOM R

Figure 41 Cyclic test, access doors in—place, 60% -flue blockage — Heater no. 5

122
CD2

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

E

(thousands)

(A> TEMPERATURE AT FLUE .Sc PILOT LIGHT

<3> TEMPERATURE: AT STACK ul DRAFT HOOD

TIME, MINUTE

a STACK DRAFT HOOD

O 2 0 AO SO SO

TIME, Ml MUTE

figure 41 ,yci i c test, access doors in

Heater no= 3

P i ace ,£> b 1 oc kaoe

123
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

(1) C-HAM BEF? PRESSURE &l EUU E DRAFT

CO TEMPERATURE AT ACCESS CO OR

Tl ME, MINUTE a CONTROL BOTTOM U BOTTOM! R

Figure 4a Cyclic test, access doors oft, no -flue blockage — Heater no. 5

124
COZ

CCtJCENTRATlON,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

CA> TEMPERATURE AT FLUE Sc PILOT LIGHT

(5) TEMPERATURE AT STACK DRAFT H OO D

STACK M I MUTE DRAFT HOOD

O 20 AO «=> LJ a'O

Fig Ltr e 42 Uyc I i

•_0St , 5CCS55 door

Heater no, Fi 5 Ot “;Q f 1 B b I DC k a. s

125
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W,

TIME. MINUTE

a CHAMBER PRESS. C — > FLUE DRAFT X .TO

<2> TEMPERATURE AT ACCESS D O O R

TIME, Ml MUTE c= CONTROL -i- BOTTOM L_ o BOTTOM R

Figure 43 Cyclic test, access doors off, 607. flue blockage —- Heater no. 5

126
C02

CONCENTRATION,

PER

CQ*JT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousands)

C-4-y temperature: AT FLUE .Sc pilot light

< 5 ) TEMPERATURE AT STACK <2c DRART MOOD

O 20 AO 60 Su

TIME, Ml MUTE

Figure 4-3 Cyclic test., access doors o-Ff . 60% -flue blockage — Heater no. 5

127
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

TEMPERATURE AT AC CESS EQOR

TEMP- AT OOMTROL «Sc HEATER BOTTOM

time;, minute <= CONTROL. -+• BOTTOM l_ o- BOTTOM R

Figure 44 Pressure test, access doors in—place, no -flue blockage — Heater no- 5

128
C02

CONCENTRATION,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(TTioij

Bonds)

i .-<+ TEMPERATURE T FLUE =3c PILOT LIGHT

1.3 — 1.2-

1.1 - ^ 1 -

Lul' ai' 11 °*® H

Go -1 o.s - 0.7 - o.e -

a. s -

0.-4- - 0.3 —

1

1 1 1 1 O U O *4-0 S U

TIME. Ml MUTE a FLUE TOR + FLUE BOT

iqure 44 ssure test — i-i pa + ptaccess doors in pi bce

no

129

j
0

< 1 } CHAMBER PRESSURE «3c FLU E DRAFT

TEMPERATURE AT ACCESS DOOR

TI ME. MINUTE CONTROL -+- BOTTOM L o BOTTOM R

Figure

Heater no,

130
COZ

COCEMTRATIGN,

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Tlio-usonds)

C-4-> TEMPERATURE AT FLUE .3c PILOT LIGHT

(5) TEMPERATURE: AT STACK <3c D RAF T HOOD

lours 4b 'ressure test, access dears in clace — Heater no = 5

i u bl g c k a •p

131
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

( 1 ) CHAMBER PRESSURE &c FLU E DRAFT

<2> TEMPERATURE AT AOCD ESS DOOR

O A 0 12 IS 20 2 A 20

TIME, M I N U TE

a CONTROL -+- BOTTOM L *> BOTTOM R

Figure 46 Pressure test, access doors in—place, 60V. flue blockage — Heater no. 5

132
C02

C0CENTRAT10N,

PER

CEJJT

TEMPERATURE,

F

TEMPERATURE,

F

CFhoueands’j

< A-'j TEMPERATL) RE AT FLUE <Sc PILOT LIGHT

TIME, MINUTE

a STACK -+ D RAFT HOOD

0 test

access door — Heater no, 5

s in Discs ue d

133
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

ITCH

W.C.

Clj C HAM E3 E R PRESSURE: FLUE DRAFT

TIME, MINUTE

a CONTROL BOTTOM l_ -2- BOTTOM R

Figure 47 Pressure test, access doors in—place, 100% flue blockage — Heater no- 5

134
CDZ

CCWCENTRAT10N.

PER

CENT

TEMPERATURE,

F

TEMPERATURE,

F

(Thousonds)

TEMPERATURE AT FLUE «Se PILOT LIGHT

('5> TEMPERATURE AT STACK ,3c DRAFT MQOO

r i gure 4-7 Hressiire test = access doors in pises, 100% 1 1 us blockays — Hester no. 5

135
( 1 > CHAMBER PRESSURE: &c. EUUE O RAFT

<2> TEMPERATURE AT AC O E S S COOR

(3) TEMP. AT CONTROL =Sc M EATER BOTTOM

TIN/IE, MINUTE

a CONTROL. a BOTTOM l_ ^ BOTTOM R

Figure 48 Pressure test, access doors off, — Heater no. 5

no flue blockage

136
DC -S P § Sr oj £S S

)

TEMPERATURE AT EL_UE cSc PILOT LIGHT

T5} TEMPERATURE AT STACK &z DRART HOOD

I X~ P ^H-f- esEure test. , access door — Heater no. 5

T i US b p

137
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

<

-! > CHAM BER PRESSURE: <3c FLU E DRAFT

C2) TEMPERATURE AT ACCESS OOOR

TIME, MINUTE

<=> CONTROL. + BOTTOM L <=> BOTTOM R

Figure 49 Pressure test, access doors o-f f , 20% flue blockage — Heater no. 5

138
ifcf-g'

C -4- j> TEMPERATURE AT FLUE Sc PILOT LIGHT

£

§Cl. 3

O id TAOK. TIME, Ml MUTE DRAFT HOOD

4:

<L>

LUA

s

i qure 49 55ur0 tist , access doers o- 1US hi oc K S. r? p

10dilE‘ n Cm u

139
TEMPERATURE,

F

TEMPERATURE,

F

PRESSURE,

INCH

W.C.

TIME, MINUTE

<= CONTROL -+- BOTTOM i_ o BOTTOM F?

Figure 50 Pressure test — Heater

access doors off,

no. 5

60% flue blockage

140
<=• mr 01

(A-'j TEM P ERATU RE AT FLUE Sc PILOT LIGHT

<S> TEMPERATURE AT STACK Sc DRART HOOD

c_? sCLUJ

i-igure 50 Pressure test — Heater

access doors a-f-f , do/: ue i OC K <5 p

141
TEMPERATURE,

F

TEMPERATURE,

F

FPfSSURE,

INCH

W.C

C 1 > OMAM BER pressure:

TIME. Ml MUTE

a CONTROL BOTTOM U o> BOTTOM R

Figure 51 Pressure test — Heater

access doors

no . 5

off , 100% flue blockage

142
C02

CONCENTRATION,

PER

CE>JT

TEMPERATURE,

F

TEMPERATURE,

F

5=51 Pres s test, access doors g++

Heater no. 5

i J U A

143
NBS-114A (REV. 2-80

U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 8 8-3724

2. Performing Organ. Report No. 3. Publication Date

MARCH 1988

4. TITLE AND SUBTITLE

Flame Roll-Out Study for Gas Fired Water Heaters

5. AUTHOR(S)

James Y. Kao, Donald B. Ward, George E. Kelly

6. PERFORMING ORGANIZATION (If joint or other than N BS, see in struction s) national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

U.S. Consumer Product Safety Commission

5401 Westbard Avenue

Washington, DC 20207

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

bi bl iography or literature survey, mention it here)

Five gas-fired water heaters (four natural gas and one LP gas) were tested in laboratory

with simulated home conditions to evaluate their flame roll-out characteristics.

Simulated variables were flue blockage, space pressure depression, access door status

(in-place and not in-place), and other related factors. Test results were compared with

those based on the proposed ANSI test method. The testing concludes that, in addition

to flue blockage, pressure depression and door status are major factors in inducing

heater flame roll-out; that poor draft hood performance contributes to the likelihood of

flame roll-out; that the proposed ANSI test method should add a temperature criterion

for determining flame roll-out; that the proposed ANSI blocked flue test appears to be

adequate for units equipped with thermal spill switches located at their access doors area. For units not equipped with these particular type of safety devices, the following

concerns were identified: 1) Water heaters which pass the proposed ANSI test, with the

access doors in place and without the need for additional safety devices, may not pass

such a test if the doors were left off, and 2) units which use devices other than

thermal switches to detect blocked flues, may pass the proposed ANSI test and still

produce dangerous flames and heat outside of their jackets under certain conditions.

Recommendations are made that CPSC and the ANSI sub-committee on water heaters consider

also requiring the interlocking of access doors with water heater operation, the use of

temperature sensing as a means of detecting flame roll-out, and the use of improved

draft hood designs and draft hood performance testing to reduce the chances of flame

roll-out

.

12.

KEY WORDS (Six to twelve entries ; alphabetical order; capitalize only proper names; and separate key words by semicolon s) flame roll-out; gas fired water heater; gas water heater; safety; water heater;

water heater test.

13. AVAILABILITY

KKl Uni imited

| | For Official Distribution. Do Not Release to NTIS

| Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

|y 1 Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

157

15. Price

$18.55

USCOMM-DC S043-P80


NBSIR 88-3725

Evaluation of a Copy Prevention Method

for Digital Audio Tape Systems

National

Engineering

Laboratory

February

1988

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The front cover illustrates the effect of the copy-protection encoder on a segment of Barbra Streisand singing "Somewhere." The upper color spectrograph

corresponds to the original recording; the dark streak through the otherwise

identical lower spectrograph shows where spectral components have been removed

by the encoder. In these spectrographs, the vertical axis corresponds to

frequency, increasing from 0 Hz at the bottom to 5000 Hz at the top. The

horizontal axis indicates time. Relative signal level is indicated by color,

as shown in the color bar below, where white corresponds to the highest signal

levels and black to the lowest levels.

RELATIVE LEVEL, dB

-90 -80 -70 -60 -50 -40 -30 -20 -10 0