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NBSIR 84-2969

Evaluation of Thimble > Chimney

Connector (Wall Pass-Through)

Systems for Solid Fuel Burning

Appliances

Joseph J. Loftus

Richard D. Peacock

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

November 1984

Prepared for: Consumer Product Safety Commission

Bethesda, MD 20016

and

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4-2969

1934

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S. Department of Energy

ishington, DC 20545

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NBSIR 84-2969 6rC.

EVALUATION OF THIMBLE - CHIMNEY

CONNECTOR (WALL PASS-THROUGH) “ ' SYSTEMS FOR SOLID FUEL BURNING

APPLIANCES /

Joseph J. Loftus

Richard D. Peacock

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Gaithersburg, MD 20899

November 1984

Prepared for: Consumer Product Safety Commission

Bethesda, MD 20016

and

U.S. Department of Energy

Washingotn, DC 20545

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

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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TABLE OF CONTENTS

Page

LIST OF TABLES iv

LIST OF FIGURES v

Abstract 1

1. INTRODUCTION 2

2. BACKGROUND 3

3. LIMITING SAFE TEMPERATURES ON COMBUSTIBLE SURFACES 4

4. TEST APPARATUS AND PROCEDURES 5

5. WALL THIMBLE SYSTEM 6

6. TEST RESULTS 7

7. DISCUSSION 8

7.1 Falling Thimble Systems 8

7.2 Systems Passing 538°C (1000°F) Exposures 8

7.3 Systems Passing 593°C (1100®F) Exposures 9

7.4 Systems Passing 649*C (1200*’F) Exposure Tests 10

7.5 Effect of Sheet Metal Liners on Surface Temperature

Rise 10

8. CONCLUSIONS 11

9. RECOMMENDATIONS 13

10. REFERENCES 14

- 111-
LIST OF TABLES

liSfTable 1. Seventeen wall thimbles tested 16

Table 2. Thimble test results 17

Table 3. Chimney Connector Systems and Clearances from Room Wall

Combustibles for Residential Heating Appliances 18,

19 , 20

-Iv-
LIST OF FIGURES

Page

Figure 1. Appliance Construction Details for Gas Fired Stove

Used in Thimble Tests 21

Figure 2. Thimble (Wall Pass Through) Testing Apparatus 22

Figure 3. Thermocouple Locations on Wood Studs and Headers for

Thimble (Wall Pass Through) Tests 23

Figure 4. Square (Sheet Metal) Thimble - Ventilated

Combustibles in Contact with Thimble 24

Figure 4(A). Square (Sheet Metal) Thimble - Ventilated

Combustibles in Contact with Thimble 25

Figure 5. Chimney Connector - Through a Wall

Combustibles at Various Distances from Connector 26

Figure 5(A). Chimney Connector

Combustibles at Various Distances 27

Figure 6. Sheet Metal Thimble - One Air Channel

Combustibles - Metal Lined - 76 mm (3 in) From Thimble ... 28

Figure 6(A). One Air Channel Thimble

Combustibles with Metal Liners 29

Figure 7. Sheet Metal Thimble - Two Air Channel

Combustibles - Metal Lined - 76 mm (3 in) From Thimble ... 30

Figure 7(A). Two Air Channel Thimble

Combustibles with Metal Liners 31

Figure 8. Two Air Channel Thimbles - 76 mm (3 in) Glass Fiber

Insulation Combustibles with Metal Liners 32

Figure 8(A). Two Air Channel Thimble - 76 mm (3 in) Glass Fiber

Insulation Combustibles with Metal Liners 33

Figure 9. Sheet Metal Thimble - Two Air Channels

Combustibles - Metal Lined - 152 mm (6 in) from Thimble .. 34

Figure 9(A). Two Air Channel Thimble - 152 mm (6 in) Air Space to

Combustibles with Metal Liners

Figure 10. Two Air Channel Thimble - 152 mm (6 in) Glass Fiber

Insulation Combustibles with Metal Liners 36

Figure 10(A). Two Air Channel Thimble - 152 mm (6 in) Glass Fiber

Insulation Combustibles with Metal Liners 37

-V-
Figure 11. Brick Masonry Patch - 216 mn (8 in) Brick Separation to

Combustibles 38

Figure 11(A). Brick Masonry Patch - Separation 216 mm (8 In) to

Combustibles in contact with Bricks 39

Figure 12. Brick Masonry Patch - 305 mm (12 in) Brick Separation

to Combustibles 40

Figure 12(A). Brick Masonry Patch - Separation 305 mm (12 in) to

Combustibles in contact with Brick 41

Figure 13. Chimney Connector Through a Wall

Combustibles (457 mm) from Connector 42

Figure 13(A). Chimney Connector - 457 mm (18 in) Air Space to

Combustibles 43

Figure 14 . Chimney Connector Through a Wall

Combustibles Protected by a Metal Sleeve and 229 mm (9 in)

Air Space 44

Figure 14(A). Chimney Connector - 229 mm (9 in) Air Space to

Combustibles Protected by a Metal Sleeve 45

Figure 15. Chimney Masonry Block - Combustibles

Contact Block 46

Figure 15(A). Chimney Masonry Block - 38 mm (1.5 in) Air Space Between

Block and Connector - Combustibles in Contact with

Block 47

Figure 16. Commercial Chimney Section - Two Air Channels

Combustibles 51 mm from Section 48

Figure 16(A). Two Air Channel Thimble - 51 mn (2 in) Air Space to

Combustibles with No Protection 49

Figure 17. Commercial Chimney Section - Insulated Channel (25 mm)

Combustibles 51 mm (2 in) from Section 50

Figure 17(A). Commercial Insulated Chimney Section 152 mm (6 in) ID

Combustibles Unprotected - Air Space 51 mm 51

Figure 18. Commercial Chimney Section - Insulated Channel (25 mm)

(1 in) Section ID (203 mm) (8 in) Combustibles 51 mm from

Section 32

Figure 18(A). Conmercial Insulated Chimney Section 203 mm (6 in) ID

Combustibles Unprotected - Air Space 51 mm (2 in) 53

Figure 19. Sheet Metal Thimble - Two Air Channels

Combustibles 51 mm (2 in) from Thimble 34

-Vi-
Figure 19(A). Two Air Channel (Sheet Metal) Thimble - 51 mm (2 in)

Air Space to Combustibles with No Protection 55

Figure 20. Commercial Chimney Section Insulated Channel 25 mm - Combustibles 229 mm from Section 56

Figure 20(A). Commercial Chimney Section - Insulated Channel 25 mm - Combustibles 229 mm from Section 57

Figure 21. Effect of Sheet Metal Liner on Surface Temperature

of Combustibles - Thimble System No. 6 58

Figure 22. Effect of Sheet Metal Liner on Surface Temperature

of Combustibles - Thimble System No. 5 59

-vll-

EVALUATION OF THIMBLE - CHIMNEY CONNECTOR

(WALL PASS-THROUGH) SYSTEMS FOR SOLID FUEL BURNING APPLIANCES

Joseph J. Loftus

Richard D. Peacock

Abstract

This report is part of an ongoing project at the

National Bureau of Standards (NBS) to evaluate the fire

safety of solid fuel burning appliance installations in

residential homes and buildings. Previous work included

evaluations of different protection devices designed to

shield room walls and ceilings from the effects of

radiant energy from hot appliance and chimney connector

pipe surfaces, the objective being to determine which

systems would help maintain surface temperatures on

combustibles within code recommended temperature levels.

For this segment a total of 17 different thimblechimney connector (wall pass-through) systems connected

to chimney connector pipes from a stove were evaluated

for their ability to provide thermal protection for

combustibles (wood studs and headers, etc.) in room

walls

Flue gases passing through the thimbles were

monitored over a range of 538 to 649"C (1000 to 1200°F)

and temperature rise measurements were made on the

surfaces of the combustibles located in proximity to the

- 1 -
thimbles. Code acceptable temperature rise values were

found for 9 of the 17 thimble systems tested at the 538 ®C

(1000“F) exposure, for 6 thimbles at 593®C (1100“F) and

for 4 thimbles at 649®C (1200®F).

Keywords: ceilings, chimneys, fire codes, fire

protection, fire tests. Interior finishes, radiant

energy, residential buildings, stoves, walls.

1. INTRODUCTION

The Consumer Product Safety Commission and the Department of Energy have

sponsored research at the Center for Fire Research in the National Bureau of

Standards to investigate fire hazard problems associated with the use of solid

fuel burning appliances (stoves) in one- and two- family homes and other

residential occupancies.

Scenarios leading to house fires are all too predictable, i.e.: the

consumer (1) failed to provide for code recommended clearances or air space

between stove surfaces and room walls, (2) failed to observe recommended

clearances between chimney connector pipes and room walls and/or ceilings, or

(3) cut a hole through a room wall to allow for passage of a thimble (wall

pass-through) or chimney connector pipe to a chimney but failed to allow for

sufficient clearances between combustibles in the room wall and the exhaust

piping system. In some cases, the consumer may even compound the hazard by

"framing out" the pass-through with wood studs and headers.

-2-
Scenarios no. 1 and 2 above were reproduced in the Center for Fire

Research laboratories and evaluations were made of the relation and effects of

clearances and radiant energy from hot stove surfaces and chimney connectors

on unprotected and protected room walls and ceilings [1,2]^. Briefly, these

reports cite a number of different protection systems that were found useful

in helping to reduce thermal effects on exposed surfaces of the room members.

Particularly effective were those systems which used a sheet metal plate or

two sheet metal plates with an insulative layer between them mounted in front

of a wall or ceiling and separated from the room surface by a 25 mm (1 in) air

space.

This report relates the results of reproducing scenario no. 3 in the

laboratory and making evaluations of the effects of clearances and radiant

energy from hot thimble systems on the surface temperature of combustibles in

room walls. Clearly, systems found to offer thermal protection to the

combustibles would help to reduce ignitions leading to house fires. Injury,

and significant property damage.

2 . BACKGROUND

Recent fire statistics [3] show an alarming increase in the number of

house fires in the United States related to wood heating. In 1978 there were

68,000 fires with an estimated dollar loss of $134 million, while in 1981 the

number totaled 130,000 fires with a loss of $265 million. This marked

increase is attributed to the growing installation and use of wood burning

stoves in homes throughout the United States and the fact that most homes are

made of combustible construction.

^Numbers in brackets refer to references given at the end of this report.

-3 -
Wood framing in close proximity to hot wall pass-through systems is

highly susceptible to Ignition because flue gases passing through thimbles can

easily develop temperatures in excess of 593®C (1100®F) [4] and because the

ignition temperature of wood is approximately 200®C (392®F). The constant

heating of wood over a long period of time also presents a hazard problem

because wood may undergo chemical changes resulting in a lowered ignition

temperature [5,6]. MacLean [7,8] reports charring of wood samples at temperatures as low as 93®C (200®F) and concludes that wood should not be exposed to

temperatures appreciably higher than 66 °C (150“F) for long periods. There

have been numerous documented fires involving the ignition of wood members

near low pressure steam pipes [9] suggesting that wood exposed to long term

low level heating should not be exposed to temperatures higher than 100“C

(212°F). Based on this evidence, building and fire codes recommend that wood

should not be exposed to temperatures higher than 100®C (212® F) and that wood

framing around Interior chimneys be separated from the chimney by an air space

of at least 51 mm (2 in) [4].

3. LIMITING SAFE TEMPERATURES ON COMBUSTIBLE SURFACES

Limiting safe temperatures on combustible surfaces in proximity to

thimble (wall pass-throughs) leading to chimneys are based on the following

Underwriters Laboratories Listings for heat producing appliances and methods

for setting clearances between appliances and combustible surfaces.

• maximum temperature rise of 65®C (117®F) above room temperature

on exposed combustible surfaces; and

-4 -
• maximum temperature rise of 50 ®C (90 °F) above room temperature

on unexposed combustible surfaces, such as beneath or behind a

shield.

The 50°C (90°F) temperature rise limitation for unexposed combustible

surfaces was used for the thimble evaluation tests.

4. TEST APPARATUS AND PROCEDURES

Figure 1 shows the mock-up gas fired stove used for the testing program.

The fire box used with the stove consisted of a radiant panel made of porous

refractory material mounted in a cast iron frame which allows for the combustion of gas on its surface. Natural gas mixed with air from a blower was used

as fuel for the stove. Venting for the stove was provided by a 152 mm (6 in)

diameter chimney connector pipe system (figure 2) which entered the wall

thimbles at a location approximately 1.32 m (52 in) from the floor. The stove

was positioned 915 mm (36 in) away from the test room wall for all tests. A

chromel alumel (24 gauge, 0.5 mm, 0.020 in) thermocouple was used to measure

flue gas temperatures. It was positioned inside the chimney connector pipe at

its center and at a point where the wall thimble and connector pipe were

joined approximately 89 mm (3.5 in) from the room walls. Figure 3 shows the

location of 12 (evenly spaced) 24 gauge chromel alumel thermocouples attached

to the exposed or protected surfaces of the combustibles (wood studs and

headers) located in the room wall and in proximity to the thimble or wall

pass-through. Gas flows to the stove were monitored so that the stove surface

temperatures were maintained at 350, 400, and 450®C (662, 752 and 842®F). At

these temperatures, flue gases exiting through the connector plpe-thlrable

-5 -
systems generated temperatures in the pipe of 538, 593, and 649®C (1000, 1100,

and 1200®F).

5. WALL THIMBLE SYSTEMS

Table 1 lists and describes the 17 different thimble (wall pass-through)

systems evaluated in this test series. Shown are the system number, type, the

number of air channels used in a thimble, the air space or clearance between

the thimble and combustibles, and whether a sheet metal liner was used to

cover the exposed surfaces of the combustibles. Sketches of the thimble

systems are shown in figures 4 to 20. The tubular sheet metal thimbles used

for system nos. 3 to 7 were fabricated by the Center for Fire Research while

the tubular metal thimbles used in system nos. 13 to 17 were commercially

available, listed chimney sections. The square sheet metal thimble (no. 1)

also was constructed by the Center, as were the brick masonry patches used for

system nos. 8 and 9. The chimney masonry block (no. 12) was a factory made

item. An examination of table 1 shows that the same tubular (2 air channel)

thimble was used for system nos. 5, 6, and 7. Nos. 5 and 7 used glass fiber

insulation between the thimble and combustible surfaces. In the case of

no. 5, the insulation thickness was 76 mm (3 in) and, in no. 7 it was 152 mm

(6 in). System no. 6 utilized an air separation of 152 mm (6 in) between the

surfaces. Sheet metal liners (28 gauge, 0.38 mm, 0.015 in) were used to cover

surfaces of combustible for tests with thimble system nos. 3 to 7.

-6-
6. TEST RESULTS

Figures 4A to 20A show plots of surface temperature rise (®C) for each of

12 different thermocouple locations on the combustible surfaces. The highest

values are shown for locations 6 and 7 directly above the hot thimble and

(except for 4A the square thimble plot) the lowest for locations 2 and 11

beneath (and farthest away) from the thimble. Peak values can be attributed

to the convection of buoyant gases In the case of air separation between the

combustible and thimble and to conduction of heat In those cases where solid

material such as brick patches separated the thimble from the combustible

material. In every case, plots for the air separation systems show cyclic

temperature rise patterns. Vertically mounted combustibles (to each side of

the thimbles) registered almost median temperature rise values at locations 3,

4, 9 and 10. While the vertical members separated from the thimble by the

brick patches showed surface temperatures only slightly less than the peak

temperatures recorded for the horizontal combustible headers located above the

thimbles.

1. Wall pass-through systems failing all of the exposure

temperature tests were: Nos. 1, 2, 3, 4, 12, 13, 14, and 16.

2. Wall pass-through systems passing 538°C (1000°F) tests were:

Nos. 5, 6, 7, 8, 9, 10, 11, 15, and 17.

3. Wall pass-through systems passing 593°C (1100®F) tests were:

Nos. 7, 9, 10, 11, 15, and 17.

-7 -
4. Wall pass-through systems passing 649°C (1200°F) tests were:

Nos. 7, 9, 10, and 17,

7. DISCUSSION

7.1 Failing Wall Pass Through Systems

Wall pass-through system nos. 1, 2, 3, 4, 12, 13, 14 and 16 failed all

exposure tests due to a lack of sufficient air space (clearance) or insulation

between the thimble and combustible surfaces in the room walls. In the case

of no. 1, the combustibles were in direct contact with the sheet metal

thimble. For system no. 2, a chimney connector pipe passed through a wall at

76 mm (3 in) clearance to the combustibles. In no. 12, a chimney connector

passed through a chimney masonry block with provision for 38 mm (1.5 in) air

clearance between the pipe and the block. Tubular system nos. 3 and 4 had one

and two air channels, respectively; but the 76 mm (3 in) clearance between the

thimbles and combustibles was not enough to provide adequate thermal protection for the combustibles. System nos. 13 and 14 were commercial chimney

sections with two air channels and one Insulated channel, respectively. Each

failed tests at 51 mm (2 in) clearances, as did no. 16, a sheet metal (two air

channel) system at the same clearance.

7.2 Systems Passing 538“C (1000®F) Exposure Tests

Passing systems were nos. 5, 6, 7, 8, 9, 10, 11, 15 and 17. As

previously described, system nos. 5, 6, and 7 used the same two air channel

thimble for each test. No. 5 had a 76 mm (3 in) thick layer of glass fiber

-8-
insulation between the thimble and combustible surfaces. No. 6 used 152 mm

(6 In) air space and no, 7 had the benefit of 152 mm (6 in) thick layer of

glass fiber insulation.

System nos. 8 and 9 met the temperature rise requirements because brick

masonry patches provided 203 and 305 mm (8 and 12 in) brick separations,

respectively, to combustible materials. Thimble nos. 10 and 11 passed the

exposure tests because they enjoyed large air space separations to combustibles. In the case of no. 10, the distance was 457 mm (18 in) while for

no. 11, the separation was 229 mm (9 in) between the connector pipe and a

sheet metal sleeve protecting the combustible materials. Thimble no. 15

qualified because it consisted of an Insulated tubular chimney section having

an ID of 203 mm (8 in). This oversize pipe section provided for a 25 mm

(1 in) air clearance all around a 152 mm (6 in) diameter chimney connector

pipe. Thimble no. 17 was the same thimble as used in system 14 which failed

all exposure tests except that its clearance to combustibles was 229 mm

(9 in).

7.3 Systems Passing 593 °C (1100°F) Exposure Tests

Passing systems were nos. 7, 9, 10, 11, 15, and 17. When tested at 593®C

(1100°F), the above previously described thimbles continued to offer thermal

protection for the combustibles located in proximity to them. System nos. 17,

9 and 10 allowed a 36, 38 and 38°C rise, respectively, on the surfaces of

combustibles, no. 7 permitted a rise to 42 “C while nos. 11 and 15 showed 50 “C

(just passing) levels.

-9 -
Missing from the 593 ®C (1100®F) listing were systems nos. 5, 6, and 8.

These systems failed to meet the code requirements by narrow margins; i.e., 4,

2, and 1®C, respectively, above the 50 ®C (90 *F) code recommended temperature

rise limitation.

7.4 Systems Passing 649^0 (1200°F) Exposure Tests

Passing systems at the 649®C (1200®F) exposure were nos. 7, 9, 10 and 17.

No, 7 had the 152 mm (6 in) thick glass fiber insulation, no, 9 had the

benefit of a 304 mm (12 in) layer of brick, no. 10 used the code recommended

air clearance to combustibles of 457 mm (18 in) and no. 17 benefited from its

229 mm (9 in) clearance. Missing from this listing were systems nos. 11 and

15, which had passed exposure tests at 538 and 593®C (1000 and 1100®F).

Thimble no. 11 failed to meet the temperature rise limit by 8*C and no. 15 by

11®C.

7.5 Effect of Sheet Metal Liners on Surface Temperature Rise

To determine the relation of metal liners in direct contact with

combustibles to surface temperature rise on combustibles, a two air channel

thimble was selected for tests. In one case, the wall pass-through system

(no. 6) was separated from the combustibles (covered and uncovered) by a

152 mm (6 in) air space; and, in another (system no. 5), it was protected by a

76 mm (3 in) thick layer of glass fiber Insulation. Figure 21 shows a comparison of results for system no. 6. Here it is shown that the uncovered

(unlined) combustible members developed lower temperatures on their surfaces

for all of the exposure tests as indicated in the following listing.

- 10-
Temperature Rise, ®C

Exposure Covered Uncovered % Decrease

538°C (1000°F) 42 39 7

System No. 6 593°C (1100°F) 52 44 15

649°C (1200°F) 68 58 15

On the basis of compliance with recommended code limitations for temperature

rise, covered materials qualify for the 538°C (1000®F) exposure while the

uncovered would be acceptable for 538 and 593°C (1000 and 1100°F) exposures.

Concerning system no. 5, an examination of the data in Figure 22 shows that

the uncovered combustible members developed lower temperatures for every

exposure and location except for positions 6 and 7 (top header) where recorded

temperatures were identical in the 593° and 649°C (1100 and 1200°F) exposures.

8. CONCLUSIONS

From an analysis of results of evaluation tests on 17 different thimble

or wall pass-through systems it was found that the NFPA Code 211 recommendations for temperature rise on the surfaces of partitions and combustibles in

room walls was met by a total of nine systems when the exposure level (as

recommended by the code) was 538°C (1000°F).

V/hen the exposure level was upgraded to 593 °C (1100°F) the number of

passing systems was reduced to six and on one further upgrade to 649 “C

(1200°F) the number of systems which limited surface temperature rise to 50°C

(90°F) or less was four.

- 11 -
Impetus for testing at the upgraded temperature levels was given by the

fact that flue gas temperatures can reach as high as 648®C (1200®F) in a

thimble or wall pass-through system.

Briefly, those passing all test exposures to 649®C (1200®F) were;

#17 A commercial insulated chimney connector section at 229 mm

(9 in) clearance

#10 A single wall metal chimney connector at 475 nm (18 in)

clearance.

#9 A brick masonry patch measuring 304 mm (12 in).

#7 A tubular sheet metal thimble with two air channels and a

152 mm (6 in) layer of fiberglass between the thimble and

combustible surfaces.

Systems passing tests to the 593®C (1100®F) exposure level were;

#11 A single wall chimney connector separated from room wall

combustibles by a 229 mm (9 in) air space and a sheet metal

sleeve protector,

#15 A commercial Insulated chimney connector with a diameter of

203 mm (8 in) which served as a pass through for a 152 mm

(6 in) diameter single wall chimney connector. Clearance to

combustibles was 51 mm (2 in)

- 12-
Systems passing tests at the 538*C (1000“F) exposure level included all of the

above plus the following:

#8 A brick masonry patch measuring 203 nm (8 in)

#6 A tubular sheet metal thimble with two air channels and a

clearance of 152 mm (6 in) from combustibles.

//5 A tubular sheet metal thimble with two air channels and a

76 mm (3 in) thick layer of fiberglass between the thimble

and combustible surfaces.

Building and fire code officials may wish to use the information generated by

these evaluation tests when considering an update of recommendations for

installation and use of wall pass-through systems and of clearances to room

wall combustibles.

9 . RECOMMENDATIONS

With the introduction of new and numerous solid fuel burning appliances

in the marketplace and with new technology directed toward more efficient

burning and conservation of fuel it is quite possible that flue gas temperatures in chimney connectors will approach values as high as 649®C (1200°F).

It thus appears desirable that the level of thermal protection for room wall

combustibles should be upgraded to ensure that the combustible materials can

withstand the effects of radiant heat transfer from hot thimbles or wall passthroughs if the thimble were to reach 649“C (1200‘*F). Possible text for model

- 13-
building code specifications for room wall combustibles protection Is detailed

below.

(1)

Connections for residential type appliances may pass through

walls or partitions constructed of combustible materials If

the connector system selected or fabricated Is Installed In

accordance with the conditions and clearances recommended In

table 3. If the connector Is made of sections of listed

factory built chimney, It shall be Installed In accordance

with conditions of the listing and the manufacturer's

Instructions. Any material used to close up an opening for

the connector shall be noncombustible material.

10. REFERENCES

[1] Loftus, J.J., Evaluation of Wall Protection Systems for Wood Heating

Appliances, Nat. Bur. Stand. (U.S.) NBSIR 82-2506; 1982 May, 61 p.

[2] Loftus, J.J. and Peacock, R.D., Clearance and Methods of Protection for

Wall and Celling Surfaces Exposed to Radiant Heating Appliances, Nat.

Bur. Stand (U.S.) NBSIR ; 1984, p.

[3] Harwood, B. and Kale, D., Fires Involving Fireplaces, Chimneys and

Related Appliances, U.S. Consumer Product Safety Commission,

1981 September, 30 p.

[4] Standard for Chimneys, Fireplaces, Vents and Solid Fuel Burning

Appliances, NFPA 211-1984, National Fire Protection Association,

Quincy, MA.

[5] McKinnon, G.P., Ed., Fire Protection Handbook, 15th Edition, National

Fire Protection Association, Boston, MA, p. 4-9 to 4-15 (1981).

[6] Shelton, J.W., Wood Heat Safety, Garden Way Publishing, Charlotte, VT

(September 1979).

[7] MacLean, J.D., Effect of Heat on Properties and Serviceability of Wood:

Experiments on Thin Wood Specimen, Forest Products Laboratory Report

No. R1471, Madison, WI (1951).

- 14-
[8] MacLean, J.D. , Rate of Disintegration of Wood Under Different Heating

Conditions, American Wood-Preservers Association (1951).

[9] Matson, A.F., Dufori, R.E. and Brun, J.F., Performance of Type B Gas

Vents for Gas Fired Appliances, Part II, Survey of Available Information

on Ignition of Wood Exposed to Moderately Elevated Temperatures,

Underwriters Laboratories, Inc., Bulletin of Research, No. 51,

Northbrook, IL (May 1959).

- 15-
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® ^ § 0) coX 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o o O o O O 0 0 0 2 cs cs cs cs 2 2 2 2 2 cs 2 2 CS 2 mo

cs I

ft*

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0)

rsm

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tH9 g cn •o g g •H X 0 o s o o g g 4J 0 0 0

cs cs cn CS CS 0 •H •H •H in m in 0 0 CO rH iH iH •H iH X X w O • • iH • 0 0 0 0 0 u 0 tn 0 0 0 0

Ui

X 4JX 4J 4J 4J 4J

h 0) 0 ¥ 0 U 0 O 0 0 0 0 CO CO CO 2 2 2 2 2 Oi PU 4J 4-1 >N 2 0 0 0 M * • •

0)aa8

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cc 0) 0) 4J9I

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p 2 2 % >1 0 010 0 0 0 0 1 '3 "S '3 XXX 3 1 i 1 i 19 X X <H <H >H >H t4 9 9 9 9 P P X X > H H H ^ H PQ « C U c 1 cn xO in X 00 c^ 2

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b0 vO in in

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O PmO CM CO o St

m St CO CO o ON

O 0 CM CO CM CM 1-H CM CM

CM

CJ o u

O' o

-it vO

OCO vO

cn O'

CO

vO

00vO

VO in

vO

in

'0- 00

>sr O'in vO inO' vO

O'

00 00

-<r

(0o>o

CO

M-lUi3

cn

(00)

pti oO Cn O

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4J

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CO3 CO

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CO cO o C

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u

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*9 iH 0 o

43e (U 0) •H CO 3

4= •H 1—1 H S Pm

(U P h O 3 Ms

vO

CM

CM

CM

00CM

O'

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in O'

CM vO

CM 00O

mT

CM

Oo oo

vO

CO

n* i-H o o CM CM

Cvi CM

CM O'

00o

O'

CO CO

O' o in

CMmCMsr

m

00CO00

CO om

r>. O'MfO'00 oin

vO

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p

CCJ P Pm

(U 0 in o i-H O' in 00 ct> vO CO On in o a O PP o CO rs CM O O' O' 00 CTV O vO 00 in s O o CM CM r—1

^s 1—1 o H v-^

4<!cO

<U PM oo O vO o rs •«o- v£> CM \o

O '0- CO <r CM vO

00 o O'm St CO CO CO CO St 00 v£>

O

CM

•<r <yi I

COm o

'O- vO

COCO

(U rH

-O • e o

•H Z H

CM CO in so 00 <7' vO
TABLE 3

Chimney Connector Systems and Clearances from Room Wall Combur.tihles

for Residential Heating Appliances

Continuous Flue Gas Temperature to 6A9°C (1200°F)

System Clearances mm/ in

132 nso (6 in) l.D. sheet

metal chimney connector ~ single wall 0.61 mm (0.02A in)

thick

A57/18

90 mm (3.5 in) thick brick

masonry wall - brick separation 305 mm (12 in) to

combustibles

152 mm (6 in) l.D. metal

commercial chimney section

with a 25 mm (1 in) thick

insulated channel

152 mm (6 in) l.D. sheet

metal chimney connector - single wall 0.61 mm (0.02A in)

thick with two 25 mm (1 in)

air channels, separated from

combustibles by a 152 nm

(6 in) thick layer of glass

fiber insulation

30A/12

229/9

152/6

1. Insulation material used as part of clearance reduction system shall have a thermal conductivity of A. 88 kg.-cal/hr m2 ®C (1.0 BTU-in/Sq ft-hr-®F) or less Q
TAi>l-F. 3 - Continued

Continuous Flue Gas Temperature to 593°C

System Clearances

Ctiimg

eonn»clo' •nd

152 ran (6 In) I.D. single vail

sheet metal chimney connector

separated from combustibles by

a 229 mm (9 in) air space and a 0.61 mm (.024 in) 24 gage sheet

metal sleeve protector

Sne.1 in.lt' wpoont 203 mm (8 in) I.D. metal commercial chimney section with a 25 mm (1 in) thick insulated

channel, serving as a pass

through for a 152 mm (6 in) I.D.

single wall sheet metal chimney

connector

mir./in

229/9

51/2

- 19 -
TABLE 3 - Continued

Continuous Flue Gas Temperature to SSS^C (1000°F)

System Clearances imr./in

HEJ

90 mm (3.5 in) thick brick masonry wall - brick separation 203 mm

(8 in) to combustibles

152 mm (6 in) I.D. sheet metal

chimney connector with two 25 mm

(1 in) air channels

203/8

152/6

Brick

wall

Fira clay — llnar - u

76min glaaa llbar Inaulallon

Thimbla

Chimnay connaclor (152mm I.D.)

Thimbla Two air ohannali aaeh 25mm

152 mm (6 in) I.D, sheet metal

chimney connector with two 25 mm

(1 in) air channels separated

from combustibles by a 76 mm (3 In) thick layer of glass fiber

insulation.

76/3

2. All clearances and thicknesses are minimums; larger clearances and thick- nesses are acceptable.

-20 -
po

162mm

diameter o

0)ccoo>

<DcE

'Eo

0)

k.0)

<D IEc

COco

'eoc

Q>EXo

CO

(U>o

4-1 w

T3

QJ •H

p>4|

CO

cc3 O

>-i O

14-1

CO

CO 4J

(U Qco

4JoD

>-i 4J

COcoo

<uoc

COaa<

<u

k-i 3

QC

•H

21

Used

in

Thimble

Tests
(D

a T3

a £

22

Figure

2.

Thimble

(Wall

Pass

Through)

Testing

Apparatus
23

Figure

3.

Thermocouple

Locations

on

Wood

Studs

and

Headers

fo

Thimble

(Wall

Pass

Through)

Tests
Sheet

metal

thimble

(457x467x114mm)

Clearance

—i

i

—

Stud

and

header

24

Figure

4.

Square

(Sheet

Metal)

Thimble

-

Ventilated

Combustibles

in

Contact

with

Thimble
120

o

LU

-I

GLD

o

o

0

s

QC

LiJ 1K

Oo‘3Sld 3drUVd3dW31

25

FlKurc

4(A).

Square

(Sheet

Metal)

Tlilinhle

-

Ventilated

CombustlbleB

In

Contact

with

Thimble
©

•—

:r ’C.

©

o

34^©

26

Figure

5.

Chimney

Connector

-

Through

a

Wall

Combustibles

at

Various

Distances

from

Connector
160

CVJ

O

rO)

00

<0

lO

CO

CsJ

o o o o o

CVJ O 00 CO

Oo ‘asid 3dniVd3cJW31

(Uu

3

oc

IH

tL,

27

THERMOCOUPLE

NO
I

28

Figure

6.

Sheet

Metal

Thimble

—

One

Air

Channel

Combustibles

Metal

Lined

—

76

iran

(3

in)

from

Thimble
140

o

o

o

0

s

cr

UJ1H

Oo ‘3Sld 3UniVa3dW31

29

Figure

6(A).

One

Air

Channel

Thimble

Combustibles

With

Metal

Liners
30

Figure

7.

Sheet

Metal

Thimble

-

Two

Air

Channel

Combustibles

Lined

-

76

mm

(3

in)

from

Thimble
120

CM

a>

00

NCO

in

CO

CM

w

3

<s ^

r-^

(Uu

3

00

o

o

o

00

o

CD

O o

CM

Oo ‘asid 3dnXVd3dkN31

31

THERMOCOUPLE

NO
32

Figure

8.

Two

Air

Channel

Thinibles

—

76

mm

(3

in)

Glass

Fiber

Insulation

Combustibles

with

Metal

Liners
120

CM

O

a>

CO

(O

LO

CO

CM

o o o o o O 00 CO

^

CM

LU

-J

0.

o

o

o

s

cr

UJ

I

Oo ‘3SIU BUniVUBdlNBl

33

Figure

8(A).

Two

Air

Channel

Thimble

-

76

mm

(3

in)

Glass

Fiber

Insulation

Combustibles

with

Metal

Liners
Air

space

(152mm)

34

Figure

9.

Sheet

Metal

Thimble

-

TWo

Air

Channels

Combustibles

Metal

Lined

-

152

mm

(6

in)

from

Thimble
120

CM

O

a>

CO

(D

lO

CO

CM

o o o o o

O 00 CO CM

GC

UJ

X

IOo ‘3Sld 3dniVH3dlW31

35

Figure

9(A).

Two

Air

Channel

Thimble

-

152

mm

(6

in)

Air

Space

to

Combustibles

with

Metal

Liners
Brick

36

Figure

10.

Two

Air

Channel

Thimble -

152

mm

(6

in)

Glass

Fiber

Insulation

Combustibles

with

Metal

Liners
120

CVJ

o

0>

CD

N.

CD

lO

Tf

CO

CNJ

O O O O O

O CD CD

^ CVJ

LU

-J

0.

O

o

o

s

QC

LU

X

»-

Oo ‘3SIU 3UniVU3d^31

37

Figure

10(A).

Two

Air

Channel

Thimble

-

152

mm

(6

In)

Glass

Fiber

Insulation

Combustibles

with

Metal

Liners
38

Figure

11.

Brick

Masonry

Patch

-

216

ram

(8

in)

Brick

Separation

to

Combustibles
120

Oo ‘asm BunivdBdiMai

c

•H00

<-{ m

CN ^

CO O

013

OC

39

THERMOCOUPLE

NO.
Combustibles

AO

Figure

12.

Brick

Masonry

Patch

-

305

mm

(12

in)

Brick

Separation

to

Combustibles
120

Oo ‘asid adfuvdadwai

UJ

Q.

O

o

0

s

GC

lU1

I41

Figure

12(A).

Hrlck

Masonry

Patch

-

Separation

305

nun

(12

in)

to

Combustibles

in

contact

with

Brick
Hole

in

wall

provides

(457mm)

air

space

between

chimney

connector

and

combustibles

42

Figure

13.

Chimney

Connector

Through

a

Wall

Combustibles

(457

mm)

from

Connector
1

10

CVJ

O

O)

00

CD

ID

CO

CVJ

o o o o o

(3) h- lO CO 1-

Oo ‘3sia 3aniva3diAi3i

(Uu

COp~ CG

(U

Ul3

CkC b.

43

THERMOCOUPLE

NO.
Ceiling

//// 4

/////// EE

o>

CNi CM

(00o>O

k- Q. 0> C 0 0 0 ® 0 0 C

JQ 0 O ® c0 O « I ® o o o 2 2 > 0

.E ^ 0 ^ > 0 0 0 o ® 0 X O 0

44

Figure

14.

Chimney

Connector

Through a

Wall

Combustibles

Protected

bya

Metal

Sleeve

and

229

mm

(9

in)

Air

Space
110

O

o>

O

S.

o

in

o

CO

0)o

toCX (U

c/5

>-i d) •H i-H <: c/3

C CO

<

<r

0)u

3

C>0

1-t

fcu

Do ‘BSIti BdniVdBdl^Bl

45

THERMOCOUPLE

NO
Chimney

connector

Combustibles^

(152mm

I.D.)

46

Figure

15.

Chimney

Masonry

Block

-

Combustibles

Contact

Block
649°C

T T

(Uu

CCc. c

c/; 1-t U Cfl •H (U <C <—

(

*r^ C J-J CO

GO

h6 3 *-* T-t 4J C

J= 4* O U DC CJ

<

m

OJu

D

oc

o

CVJ o o o o

O CO CO^

r*

Oo ‘3Sld 3aniVd3cdl^31

o

CSJ

47

THERMOCOUPLE

NO
Sheet

metal

supports

O 0) cEO

48

Figure

16.

Commercial

Chimney

Section —

Two

Air

Channels

Combustibles

51

ram

from

Section
120

Oo ‘3SIU BdniVU3dl^31

o

OJu

COc.

<

v£>

49

THERMOCOUPLE

NO
Sheet

metal

supports o

*>oc

LU

O

50

Figure

17.

Commercial

Chimney

Section -

Insulated

Channel

(25

mm)

Combustibles

51

nm

(2

in)

from

Section
120

Oo ‘BSIU 3»niVU3dl^31

Q

t—

C

•HvO

E

e E

CvJ LO rH

1^ iO C OJ c a

o o u u

<

(U3

oc

u.

51

THERMOCOUPLE

NO
Sheet

metal

supports

o

o

c

c

0) c

c

ca £

o

© "D

E

E

O 52

Figure

18.

Commercial

Chimney

Section

-

Insulated

Channel

(25

ram)

(1

in)

Section

ID

(203

mm)

(8

in)

Combustibles

51

mm

from

Section
120

CVJ

o

0)

GO

CO

in

CO

CNJ

o o o o o

O 00 CO CNJ

Oo ‘asm 3dfuvd3cJk^3i

—' CN E

E E b —I

«NI LO

E E

C C

u u

<

cc

cc

53

THERMOCOUPLE

NO.
0) ©

c

I II

O 00 lO

. CO CM

O

o

©

c

c

o

o

>

©

c

E

!E

O

©

>

o

c

LU

E

E

CM

54

Figure

19.

Sheet

Metal

Thimble

-

Two

Air

Channels

Combustibles

51

mm

(2

in)

from

Thimble
100

c

•H

E

E C

O

m j_i o

I (U

4-1

(1) o

1~~i 1-1 CL.

<

<V ^ CJN

04

L-3

(M.

Uo o o o o

00 CD <N

Oo ‘3Sld 3aruvd3dl^3i

55

THERMOCOUPLE

NO.
Sheet

metal

supports

o

o

56

Figure

20.

Coiranercial

Chimney

Section

-

Insulated

Channel

25

Combustibles

229

mm

from

Section
100

IE

E

m

CN

0)c

c

cc X.o

0)

E E o o o o

oCNo

3

&c

tH

tu

o o o o o

00 CO CM

Oo asm adruvdadi^ai

THERMOCOUPLE

NO
o o o o o o

O 00 (O 't CM

Oo 3SIU aunivuad^ai

58

THERMOCOUPLE

NO
100

T T T

o

Q>^ T5

<D 0)

> k.

O O

0 >

C O

D O

1

1

o

00

Oo 3Sld 3drUVd3dW31

OJVj3

iJW

>-i (Ua

E

dJ H

<U m

(U u

*4-1 w o

CN

Csj

(U

)-> 3

bC

1-4 u.

59

THERMOCOUPLE

NO
NBS.114A IREV. 2-eo) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See Instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 84-2969

2. Performing Organ. Report No. 3. Publication Date

November 1984

4.

TITLE AND SUBTITLE

EVALUATION OF THIMBLE- CHIMNEY CONNECTOR

(WALL PASS-THROUGH) SYSTEMS FOR SOLID FUEL

BURNING APPLIANCE'S

5.

AUTHOR(S)

Joseph J. Loftus and Richard D. Peacock

6.

PERFORMING ORGANIZATION (If joint or other than NBS, see Instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contraet/Grant No.

8. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, State. ZIP)

Consumer Product Safety Commission Department ot Energy

Westbard Towers Building, Suite 760 and 1000 Independence Avenue, S.W,

Washington, D. C. 20207 Washington, D. C. 20585

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information, if document includes a significant

bibliography or literature survey, mention it here) This report is part of an ongoing project at the National Bureau of Standards (NBS) to

evaluate the fire safety of solid fuel burning appliance installations in residential

homes and buildings. Previous work included evaluations of different protection devices designed to shield room walls and ceilings from the effects of radiant energy

from hot appliance and chimney connector pipe surfaces, the objective being to determine which systems would help maintain surface temperatures on combustibles within code

recommended temperature levels. For this segment a total of 17 different thimblechimney connector (wall pass-through) systems connected to chimney connector pipes fron

a stove were evaluated for their ability to provide thermal protection for combustibles

(wood studs and headers, etc.) in room walls. Flue gases passing through the thimbles

were monitored over a range of 538 to 649®C (1000 to 1200®F) and temperature rise

measurements were made on the surfaces of the combustibles located in proximity to the

thimbles. Code acceptable temperature rise values were found for 9 of the 17 thimbles

systems tested at the 538°C (1000°F) exposure, for 6 thimbles at 593°C (1100°F) and

for 4 thimbles at 649°C (1200°F).

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolons)

chimneys; fire codes; radiant energy; residential buildings; stoves; walls; wood.

13.

AVAILABILITY

[3T1 Unl ImIted 03] 1^0'' Official Distribution, Do Not Release to NTIS rn Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

66

15. Price $10 . 00

USCOMM-DC 6O43-P80