# Cord Wood Testing in a Non-Catalytic Wood Stove

Final Report

Prepared for:

U.S. Environmental Protection Agency

EPA Contract No. EP-D-10-096, WA 4-04

EC/R Incorporated, Prime Contractor

Prepared by:

Brookhaven National Laboratory

T. Butcher, R. Trojanowski, G. Wei

June 30, 2014

### 1 

## Abstract

EPA Method 28 and the current wood stove regulati ons have been in-place since 1988. Recently,

EPA proposed an update to the existing NSPS for wood stove regulations 1 

### which includes a plan

to transition from the current crib wood fuel to cord wood fuel for certification testing. Cord wood

is seen as generally more representative of fiel d conditions while the crib wood is seen as more

repeatable. In any change of certification test fuel, there ar e questions about the impact on

measured results and the correlation between tests w ith the two different fuels. The purpose of the

work reported here is to provide data on the pe rformance of a non-catalytic stove with cord wood.

The stove selected has previously been certif ied with crib wood which provides a basis for

comparison with cord wood. Overall, particulate emissions were found to be considerably higher

with cord wood.



## Introduction

Today, in both developed and developing countries , biomass remains an important energy source

for heating and cooking. Wood stoves in particul ar are the most popular wood heating option as

they are flexible and economical. Wood stoves suppl y heat directly to the space, unlike central

boilers/furnaces which require a system of ducts to supply heat. They’re easy to install, require

little space, and involve little maintenance.

Currently wood stoves in the U.S. are tested

for certification using EPA Method 28

“Certification and Auditing of Wood

Heaters” 2,3 

### . This requires testing in 4 burn

categories using dimensional lumber (cribs)

of Douglas Fir. The Douglas Fir crib fuel

consists of 2 x 4 and/or 4 x 4 pieces which

are nailed or stapled together with the

proper spacing to establish consistency of

the fuel load (see Figure 1). Tests run with

crib wood do not permit any round or

special angular cuts to the fuel pieces and

are geometrically similar to the shape of the

firebox. The crib fuel mu st not be treated or

kiln-dried and also meet the moisture

1 U.S. EPA, Standards of Performance for New Residentia l Wood Heaters, New Reside ntial Hydronic Heaters and

Forced-Air Furnaces, and New Residentia l Masonry Heaters; Proposed Rule, Federal Register, Vol. 79, No. 22,

Feb3, 2014.

2 “Method 28- Certification and Auditing of Wood H eaters”, EPA, http://www.epa.gov/fem/methcollectns.htm

3 http://www.epa.gov/ttnemc01/promgate/m-28.pdf Figure 1: Test fuel crib arrangement

### 2 requirement of 16 to 20% on a wet basis (19 to 25% on a dry basis). Despite the efforts to maximize

consistency amongst tests and stoves, the argument s till remains that cord w ood (split logs) is more

representative of field use a nd therefore real-world emissions . Under Method 28 particulate

emissions are measured using either a dilution tu nnel method (5G) or an in-stack method (5H).

In the proposed new regulations for residential wood heating devices, known as the New Source

Performance Standards or “NSPS”, the EPA has proposed switching the fuel used for testing

devices in future years- from crib to cord wood.

The goal of this work was to compare the emissi on test results for cribs and cord wood in a noncatalytic stove. Crib data was provided by EPA from the EPA certification test data. In this testing

particulates were measured using method 5H in contrast to method 5G used in the current work.

Cord wood tests were conducted in accordan ce to the current draft ASTM method and

considerations from Method 28.



## Experimental

The stove tested for this report was an EPA cer tified non-catalytic stove, towards the cleaner end

of the EPA certification list, i.e. <2.0 g/hr w ith crib wood. To ensure complete combustion the

stove includes an insulated firebox, a system of baffl es to create a longer, hotter gas flow path, and

a damper to control the amount of air introduced under the fire and to the glass door “air wash”.

Secondary air is introduced through ports at the top of the combustion chamber.

The fuel test charge was cord wood, specifically red oak with an average moisture content of 19

to 25% on a dry basis. During testing, fuel pieces were placed in the firebox parallel to the

longest firebox dimension. A full lo ad was considered as 7 pounds per cubic foot in all tests,

which is equivalent to 24 pounds of the fuel ch arge for the appliance. This loading was

selected for consistency with the prior Method 28 crib w ood data. This loading is

different than is being considered in the developing ASTM method.

The test fuel was prepared by the State University of New York, College of Environmental

Science and Forestry (ESF) under the direction of Dr. William Smith. The preparation

involved conditioning fresh cord w ood under controlled temperature and humidity conditions

for time periods on the order of weeks. The mo isture measurement meth od developed in the

work at ESF was used in this work and involves averaging multiple “shell” and “core”

measurements 4 

### . An example of the wood moisture data from May 20 th 

### , may be seen in Table 1

4 Smith, W.B., Evaluation of Wood Fuel Moisture Measur ement Accuracy for Cord wo od-Fired Advanced Hydronic

Heaters”, Report 14-12 to NYSERDA, March 2014. Available at www.nyserda.ny.gov.

### 3 Table 1: Cord wood Moisture Content Determination May 20 th , 2014

Test # Cat 4 Name/s: GW

Date: 5/20/2014 Moisture Meter: RDM3

Weight A

‐

end B

‐

center C

–

end Predicted

Piece %MC

Piece

# lbs shell Core shell Core shell Core A

‐ B B

‐ C A

‐ B &

B

‐ C

1 5.16 10.9 17.1 13.3 24.9 12.3 17.3 16.0 17.0 16.5

2 4.89 13.1 22.1 18.8 31.9 13.6 23.1 20.4 21.9 21.1

3 4.13 12.3 21.2 17.8 32.1 12.3 17.3 18.8 19.9 19.4

4 5.18 12.1 24.5 20.4 33.4 14.4 21.3 21.0 22.4 21.7

5 4.75 17.3 38.4 15.8 41.5 16.7 37.4 27.9 27.9 27.9

Sum 24.1 Average 20.8 21.8 21.3



### The fuel that was used for the tests was free of any notable decay, fungus and loose bark. The

fuel charge and kindling was loaded as per the manufacturer’s specifications. Kindling was

weighed prior to each test; however, moisture of the kindling pieces was not recorded. The

dimensions of each fuel piece were recorded fo r each test as well. An example from May 20 th 

### may

be seen in Figure 2.

Figure 2: Fuel wood dimensions May 20th, 2014

### 4 The stove vented into a dilution tunnel hood that collected exhaust gas and mixed it with room

air. The dilution ratio was controlled by a set of in-line dampers that a llowed the air velocity

in the dilution tunnel to be adjusted. The dilution tunnels seams and joints were sealed to

prevent leakage. The velocity and pressure were measured with a pitot tube and digital

pressure gauge through each test. The dilution tunnel had a diameter of 8 inches and met the

specifications of ASTM E2515-10.

Particulate emission measurements were ma de from the dilution tunnel and conducted in

compliance with ASTM E2515 Standard Test Method for Determination of Particulate Matter

Emissions Collected in a Dilution Tunnel . Two identical dual-filter EPA Method 5 sampling

trains 5 

### were operated simultaneously. The two samp ling trains allow for quality control and

confirmation of the PM data collected over a pe riod. Each sampling train consisted of two glass

fiber filters in series that were each 47 millimeters in diameter.

Filters and probes were desiccated for at leas t 24 hours or until the weight remained constant.

The components were weighed prior to the test. The probes were also rinsed with acetone before

sampling and initial weights are taken to remove any PM that may have accumulated in the

probe from prior tests. When loading and meas uring any filters and probes, gloves and tweezers

were used to eliminate excess wei ghts attributed to dirt and oils from skin contact. Leak checks

of the sampling system were performed before star t of testing to ensure no leakage exists that

would result in less dilution tunnel gas pass ing through the filters than indicated by the

metering system.

Flue gas samples for analysis we re taken from the dilution tunnel and directly from the flue. For

sampling from the dilution tunnel, water vapor wa s removed using a thermo electric cooler/drier.

Gas analysis in the dilution tunnel included oxyg en and carbon monoxide. Analysis of samples

from the flue gas included oxygen. A decision was made to measure carbon monoxide from the

dilution tunnel to allow direct calculation of th e emission rate of CO (concentration × dilution

tunnel flow rate).

Carbon monoxide was measured using a Rosemount Analytical model 880 NDIR Carbon

Monoxide analyzer. Oxygen was measured in both the dilution tunnel and the hot stack via a

Beckman model 755 Oxygen Analyzer. Both analy zers have a set of four ranges: 10%, 25%,

50% and 100%. The signals from all analyzer s were logged at a 5 second intervals.

Temperatures were also measured continuously at five second increments, using TC-08

thermocouple data loggers made by Pico Technologies with type K thermocouples. Type K

5 Model 511 from Apex Instruments

### 5 thermocouples are capable of measuring temper atures to within +/- 1.5°. The thermocouples

were calibrated using an Omega CL1000 dry calibration block and were in compliance with

National Institute of Standards and Technology (NIST) Monograph 175, Standard Limits of

Error.

Test Plan

Three emission tests in each of the four categories of Method 28 were planned to allow evaluation

of reproducibility with cord wood and provide c onsistent data for comparison with crib wood.

However, with cord wood, the size, species, and moisture content of the test fuel can all have

impacts on the test results. Therefore, for the pur poses of this work, the test cord wood was guided

by draft cord wood specifications and proce dures under active development by ASTM.

### 6 

## Test Results

Testing was successfully completed in Method 28 Categories IV, III, and II. It was not found

possible to achieve the Cat. I burn rate with this fuel even when the air control damper was fully

closed. In this case Method 28 provides a method for determin ing average emissions based on

weighting the results of the other three categories in which the stove was tested. It should be noted

that in the earlier certif ication testing with crib wood, Categor y I operation was also not achieved.

Table 2, below provides a summary of the test s done in each category a nd includes run-average

burn rate. For each of the three categories achieved in testing Figures 3 to 14, below provide a

comparison of the measured trends of the key parameters along with the same parameters measured

during crib wood testing. The crib wood data wa s adopted from the submitted certification test

reports.

Table 2: Outline of Tests Completed



### Category Fuel Date Burn Rate (kg/hr)

IV Crib

- 1 

### 2.35

IV Cord 19-May 2.46

IV Cord 20-May 2.33

IV Cord 21-May 2.57

III Crib

- 1 

### 1.77

III Cord 23-May 1.58

III Cord 28-May 1.51

III Cord 29-May 1.82

III Cord 30-May 1.32

III Cord 4-June 1.31

II Crib

- 1 

### 1.12

II Cord 5-June 1.03

II Cord 9-June 1.13

II Cord 10-June 1.09

II Cord 11-June 1.16

I Crib

- 1,2 

### 0.99

1. Results reported in 2004 as part of qualifica tion test report done by test lab.

2. As of July 1, 1990, Method 28 allowed Cat 1 to be less than 1.00 ve rsus the original

<0.80. [Section 5.2 of Method 28]

### 7 Cat IV

The Cat IV trend comparisons are shown in Figures 3 to 6 below. In this case the burn rate, flue

gas oxygen, and flue gas temperature trends are s een as very similar betw een the cord- and crib

wood cases. In addition there is very good repeatabil ity among the cord wood tests, i.e. within 3%

of the average g/hr. It is important to mention the amount of fuel consumed within the first 30

minutes was 7.5, 7.5, 9.0 lbs for the cord wood, and 9.6 lbs for the crib wood (cord wood tests

May 19 th 

### , May 20 th 

### , and May 21 st 

### , respectively). On the 19 th 

### , the door was closed immediately

causing for a slower light off and lesser consumpti on rate within the first 30 minutes, however it

was a good match to the crib wood light off from 2004. After some discussion it was decided to

leave the door open longer (als o recommended by the manufacturer) to prevent oxygen starvation

which can cause higher emissions.

Table 3: Cat. IV Data Summary

Cat. IV RUN # Crib 1 2 3 AVERAGE

Date 2004 19

‐ May 20

‐ May 21

‐ May

Particulate

Emissions Units

Concentration mg/m^3

‐ 6.933 6.747 7.037 6.905

Emissions Rate grams/hr 0.78 4.291 4.159 4.355 4.268

Emissions Factor grams/kg 0.33 1.399 1.422 1.269 1.363

Total Mass

Captured Mg 63.6 8.300 8.050 7.200 7.850

Heat Output

(EPA Default) BTU/hr

Fuel Burn Rates

Average Burn

Rate kg/hr (dry) 2.35 2.46 2.33 2.57 2.45

lb/hr (dry) 5.18 5.43 5.13 5.67 5.41

Fuel Moisture

Content

Kindling (wet

basis) % 14.966 N/A N/A N/A N/A

Pretest Fuel (wet

basis) % 18.897 20.1 19.9 21.2 20.4

Test Fuel (wet

basis) % 17.519 20.6 21.3 25.7 22.53

### 8 Air to Fuel Ratio N/A N/A N/A N/A N/A

Average Stack

Gas

Avg CO2 % 7.48 N/A N/A N/A N/A

Avg O2 % N/A 12.8 12.9 11.43 12.38

Avg CO % 0.58 0.03 0.03 0.03 0.03

Avg moisture % 6.35 10 10 10 10

Average Stack

Gas Emissions

CO g/kg 74.13

g/hr 174.14

Average

Temperatures

Stack Gas °F 403 437 420 415 424

Firebox °F 984 N/A N/A N/A N/A

Secondary °F 1093 N/A N/A N/A N/A

Catalytic

Combustor °F N/A N/A N/A N/A N/A

Top °F 311 436 420 459 438

Left Side °F 404 548 555 604 569

Back °F 232 86 86 86 86

Right Side °F 424 378 363 410 384

Bottom °F 352 N/A N/A N/A N/A

Temperature

Change °F

‐ 74

‐ 86.7

‐ 18.4

‐ 12.9

‐ 39.3

Test Chamber

Environment

Average

Barometer in. Hg 30.17 29.97 29.91 29.88 29.92

Average

Temperature °F 79 73 75 67 72

Ambient

Moisture % H2O 1.45

Relative

Humidity %RH 33.5 33.8 24.4 42 33.4

Air Velocity m/sec 0

Fuel Weight and

Burn Time

### 9 Density (dry

basis) gm/cm^3 N/A N/A N/A N/A N/A

Coal Bed Weight Lbs 4.9 6.3 5.6 5.1 5.7

Pre Test Fuel

(inc. kindling) Lbs 47.1 28.8 22.5 28.3 26.5

Test Fuel Lbs 22.5 24.4 23.9 24.2 24.2

Burn Time Min 215 213.92 219.92 190.42 208.1

Figure 3: Cat. IV fuel consumption trends 440 445 450 455 460 465 470 475

0 50 100 150 200 250ScaleMass(lbs)

Time (min) Crib

Cord 5/19

Cord 5/20

Cord 5/21

### 10 Figure 4: Cat. IV st ack temperature trends

Figure 5: Cat. IV stack oxygen trends 0 100 200 300 400 500 600 700

0 50 100 150 200 250StackTemperature(F)

Time (min) Crib

Cord 5/19

Cord 5/20

Cord 5/21

4 6 8 10 12 14 16 18 20

0 50 100 150 200 250StackO2(%)

Time (min) Crib

Cord 5/19

Cord 5/20

Cord 5/21

### 11 Figure 6: Cat. IV ca rbon monoxide trends 0 100 200 300 400 500 600

0 50 100 150 200 250COinDilutionTunnel(ppm)

Time (min) Cord 5/20

Cord 5/19

Cord 5/21

### 12 Cat III

The Cat III trend comparisons are shown in Figures 7 to 10 below. Again, in this case the burn

rate, flue gas oxygen, and flue gas temperature tre nds are seen as very similar between the cordand crib wood cases. However, the cord wood was wetter (22.0%) versus the 2004 crib wood case

(17.8%). The repeatability in the flue gas oxyge n and temperature between the individual cord

wood tests is not as clear as with the Cat IV tests. The fuel c onsumed within the first 30 minutes

for the crib, May 23 rd 

### , May 28 th 

### , May 29 th 

### , May 30 th 

### , and June 4 th 

### tests was 5.6, 5.7, 7.9, 7.6, 7.6,

and 6.3 lbs, respectively. For these tests the door was left partially open for a full five minutes after

the fuel charge was added.

Table 4: Cat. III Data Summary

Cat. III RUN # Crib 1 2 3 4 5 AVERAGE

Date 2004 23

‐ May 28

‐ May 29

‐ May 30

‐ May 4

‐ Jun

Particulate

Emissions Units

Concentration mg/m^3

‐ 9.973 13.403 26.009 14.166 25.562 17.822

Emissions Rate grams/hr 1.1 6.461 8.748 17.402 9.398 16.605 11.723

Emissions

Factor grams/kg 0.62 3.185 4.555 7.301 5.495 9.860 6.079

Total Mass

Captured mg 127.8 17.450 24.600 40.000 30.500 53.600 33.230

Heat Output

(EPA Default) BTU/hr

Fuel Burn

Rates

Average Burn

Rate kg/hr

(dry) 1.77 1.58 1.51 1.82 1.32 1.31 1.51

lb/hr

(dry) 3.9 3.49 3.33 4.01 2.92 2.89 3.33

Fuel Moisture

Content

Kindling (wet

basis) % 13.917 N/A N/A N/A N/A N/A

Pretest Fuel

(wet basis) % 18.8 19 18.38 17.51 18.7 14.6 17.638

Test Fuel (wet

basis) % 17.8 22.1 21.5 21.58 22.58 22.2 21.992

### 13 Air to Fuel

Ratio N/A N/A N/A N/A N/A N/A N/A

Average Stack

Gas

Avg CO2 % 6.76 N/A N/A N/A N/A N/A N/A

Avg O2 % N/A 13.2 12 12.34 12.59 10.8 12.186

Avg CO % 0.87 0.04 0.03 0.04 0.04 0.03 0.0369568

Avg moisture % 5.92 10 10 10 10 10 10

Average Stack

Gas Emissions

CO g/kg 117.02

g/hr 207.59

Average

Temperatures

Stack Gas °F 335 309 281 298 240 248 275.2

Firebox °F 725 N/A N/A N/A N/A N/A

Secondary °F 953 N/A N/A N/A N/A N/A

Catalytic

Combustor °F N/A N/A N/A N/A N/A N/A

Top °F 334 346 336 333 275 295 317

Left Side °F 370 450 444 449 417 417 435.4

Back °F 313 88 82 81 86 84 84.2

Right Side °F 376 330 355 352 318 331 337.2

Bottom °F 325 N/A N/A N/A N/A N/A

Temperature

Change °F

‐ 67.7

‐ 99

‐ 156.9

‐ 69.59

‐ 134.28

‐ 110.67

‐ 114.088

Test Chamber

Environment

Average

Barometer in. Hg 30.21 29.8 29.92 30.13 29.96 29.7 29.902

Average

Temperature °F 79 72 71 66 72 76 71.4

Ambient

Moisture % H2O 1.2

Relative

Humidity %RH 33.5 99.2 91.2 59.3 58.5 74.6 76.56

Air Velocity m/sec 0

Fuel Weight

and Burn Time

### 14 Density (dry

basis) gm/cm^3 N/A N/A N/A N/A N/A N/A N/A

Coal Bed

Weight lbs 5.3 5 5.3 6 5.7 6.1 5.62

Pre Test Fuel

(inc. kindling) lbs 62.6 26.4 26 26.9 28.6 28.1 27.20

Test Fuel lbs 23 24.5 24 24.2 25 24.7 24.48

Burn Time min 290 328.00 339.17 283.75 398.15 399.02 349.62

Figure 7: Cat. III fuel consumption trends 440 445 450 455 460 465 470 475

0 50 100 150 200 250 300 350 400 450ScaleMass(lbs)

Time (min) Crib 2004

Cord 5/23

Cord 5/28

Cord 5/29

Cord 5/30

Cord 6/4

### 15 Figure 8: Cat. III st ack temperature trends

Figure 9: Cat. III stack oxygen trends 0 100 200 300 400 500 600 700 800

0 50 100 150 200 250 300 350 400StackTemperature(F)

Time (min) Crib

Cord 5/23

Cord 5/28

Cord 5/29

Cord 5/30

Cord 6/4

4 6 8 10 12 14 16 18 20 22

0 50 100 150 200 250 300 350 400StackO2(%)

Time (min) Crib 2004

Cord 5/23

Cord 5/28

Cord 5/29

Cord 5/30

Cord 6/4

### 16 Figure 10: Cat. III carbon monoxide trends 0 200 400 600 800 1000 1200 1400 1600

0 50 100 150 200 250 300 350 400COinDilutionTunnel(ppm)

Time (min) Cord 5/23

Cord 5/28

Cord 5/29

Cord 5/30

Cord 6/4

### 17 Cat II

The Cat. II trend comparisons are shown in Figures 11 to 14 below. In this case the burn rate, flue

gas oxygen, and flue gas temperature trends are s een as very similar betw een the cord- and crib

wood cases. In addition there is very good repeatability among the co rd wood tests, i.e., within

10% of the average g/hr. The cord wood moisture content (19.6 %) was somewhat higher than the

crib wood case (17.1 %). The consumption of fuel for the first 30 minutes for the crib, June 5 th



### ,

June 9 th 

### , June 10 th 

### , and June 11 th 

### tests was 3.7, 4.5, 3.9, 4.0, and 3.2, respectively. For the Cat. II

tests, the door was closed completely within two minutes of loading the fuel charge to prevent a

high initial consumption rate cau sing for an overall higher consum ption rate and higher category.

Table 5: Cat. II Data Summary

Cat. II RUN # Crib 1 2 3 4 AVERAGE

Date 2004 5

‐ Jun 9

‐ Jun 10

‐ Jun 11

‐ Jun

Particulate

Emissions Units

Concentration mg/m^3

‐ 54.497 72.424 115.583 128.783 92.822

Emissions Rate grams/hr 2.230 36.012 48.088 34.756 41.123 39.995

Emissions

Factor grams/kg 2.000 27.884 34.697 31.174 27.677 30.358

Total Mass

Captured mg 638.600 142.200 181.600 296.650 312.750 233.300

Heat Output

(EPA Default) BTU/hr

Fuel Burn

Rates

Average Burn

Rate kg/hr

(dry) 1.12 1.03 1.13 1.09 1.16 1.10

lb/hr

(dry) 2.47 2.28 2.48 2.39 2.57 2.43

Fuel Moisture

Content

Kindling (wet

basis) % 13.119 N/A N/A N/A N/A N/A

Pretest Fuel

(wet basis) % 19.041 18.1 15.9 14.9 14.7 15.9

Test Fuel (wet

basis) % 17.118 20 18.9 18.1 21.2 19.55

Air to Fuel

Ratio N/A N/A N/A N/A N/A

Average Stack

Gas

Avg CO2 % 5.87 N/A N/A N/A N/A N/A

### 18 Avg O2 % N/A 13.1 13.4 11.5 11.6 12.4

Avg CO % 1.11 0.03 0.04 0.09 0.08 0.060396

Avg moisture % 5.04 10 10 10 10 10

Average Stack

Gas Emissions

CO g/kg 160.7

g/hr 179.99

Average

Temperatures

Stack Gas °F 238 173 174 164 175 171.5

Firebox °F 607 N/A N/A N/A N/A N/A

Secondary °F 692 N/A N/A N/A N/A N/A

Catalytic

Combustor °F N/A N/A N/A N/A N/A N/A

Top °F 268 216 205 219 207 211.75

Left Side °F 306 357 330 333 347 341.75

Back °F 251 88 88 92 92 90

Right Side °F 316 271 295 279 288 283.25

Bottom °F 179 N/A N/A N/A N/A N/A

Temperature

Change °F

‐ 77

‐ 167

‐ 204.5

‐ 219.2

‐ 142.5

‐ 183.3

Test Chamber

Environment

Average

Barometer in. Hg 30.08 29.55 29.87 29.86 30.01 29.8225

Average

Temperature °F 75 69 69 73 73 71

Ambient

Moisture % H2O 1.2

Relative

Humidity %RH 29.5 93.8 91.7 88.35 71.95 86.45

Air Velocity m/sec 0

Fuel Weight

and Burn Time

Density (dry

basis) gm/cm^3 N/A N/A N/A N/A N/A N/A

Coal Bed

Weight lbs 5.6 5.9 6.7 5.6 5.3 5.875

Pre Test Fuel

(inc. kindling) lbs 64.2 27.1 28.2 28.4 27.9 27.9

Test Fuel lbs 22.6 23.9 24 24.9 25.8 24.65

Burn Time min 455.00 503.17 470.75 510.92 475.00 489.9583

### 19 Figure 11: Cat. II fuel consumption trends

Figure 12: Cat. II stack oxygen trends 440 445 450 455 460 465 470 475

0 100 200 300 400 500 600ScaleMass(lbs)

Time (min) Crib 2004

Cord 6/5

Cord 6/9

Cord 6/10

Cord 6/11

4 6 8 10 12 14 16 18 20 22

0 100 200 300 400 500 600StackO2(%)

Time (min) Crib 2004

Cord 6/5

Cord 6/9

Cord 6/10

Cord 6/11

### 20 Figure 13: Cat. II st ack temperature trends

Figure 14: Cat. II carbon monoxide trends 0 100 200 300 400 500 600

0 100 200 300 400 500 600StackTemperature(F)

Time (min) Crib

Cord 6/5

Cord 6/9

Cord 6/10

Cord 6/11

0 500 1000 1500 2000 2500 3000

0 100 200 300 400 500 600COinDilutionTunnel(ppm)

Time (min) Cord 6/5

Cord 6/9

Cord 6/10

Cord 6/11

### 21 

## Wet Cord wood Evaluation

In an exploratory test a high bur n rate test was done using very wet cord wood. This was done

specifically to provide an eval uation of the impact that burni ng very we wood might have on

emissions. Test procedures were the same as was followed with the other test fuels. Wood

moisture content was 48.4% on a wet basis. Particul ate emissions were found to be extremely high,

50.6 g/hr over the run, 11.8 times higher than the aver age emission rate with the drier test fuel in

Category IV.



## Discussion

The test results presented here cl early show much higher emissions with the cord wood tested vs

the crib wood results included in the certification test report. This is particularly clear for the low

input, Cat II test. The burn rate, flue gas temp erature, and flue gas oxygen however, would not

lead to the obvious conclusion th at the burn characteristics with the cord wood are very much

different than with the crib wood. The only notable exception to th is is the Cat II test, where the

stack temperature was clearly hi gher for the crib wood tests.

There are several factors which c ould contribute to the differences observed between the cord and

crib wood results:

 The cord wood does not have the defined air flow path between the pieces as there is in the

crib wood tests. It should be noted that in loading the cord wood into the firebox great

effort was taken to space the pi eces as per the manufacturer’s loading instructions and with

spacing between the pieces as uniform as possible.

 The crib wood tests were done with Douglas Fir while the cord wood used here was red

oak. It should be noted that red oak is an accep table fuel in at least the draft version of the

ASTM cord wood protocol bei ng evaluated in this work.

 With the specific cord wood used in this test , the shell was drier than the average and the

core wetter. This could have a ffected the burn characteristics.

During the Cat II, low burn rate tests, the glass door on the front of the st ove became blackened

and considerable carbon deposits we re noted in the top of the stove and flue pipe after the test.

This observation suggests that there was not adequa te air in the primary section during this test.

The overall exhaust flue gas oxygen was high, indicat ing adequate air for combustion, but much

of this air may have been entered as secondary air and not contributed to achieving burnout of the

semivolatile organics. For optimal performance of this stove on cord wood, some rebalancing of

the primary air / secondary air ratio may be required. It is possible as well that the details of the

air damper setting and the procedure for loading and the timing of the startup operations

contributed to differences between cord wood and reported crib data.

The results in this work can be compared with those of a catal ytic stove conducted independently

of this work and by a manufacturer. In the case of the catalytic stove, a direct comparison was

made between cord and crib wood test results. The emission rate of particulates was found to be

2.2 times higher with cord wood in Category II. At higher burn rates the emissions were closer

with the cord wood emission rate 32% higher. This comparison is made based on direct method

5G emission measurements.

### 22 

## Conclusions

These results indicate that there can be very si gnificant differences between the emissions during

certification testing between cord wood and the Me thod 28 crib wood. In the lowest burn rate

tested, the particulate emission rate with cord wood was found to be 18 times higher than was

reported with the crib wood testing.