1. Repeatability of Cordwood Combustion Particulate Measurements
Summary of Studies with the Condar Portable Dilution Tunnel
Norbert Senf
July 29, 2017
mha-net.org

2. Summary of Results
COV coefficient of variation = standard deviation/average X 100 gives a percentage value for variability (lower is better)

3. Condar Portable Dilution Tunnel

4. Condar schematic

5. Condar Portable Dilution Tunnel

6. Condar used in 2006 New Zealand pellet stove field study

7. OMNI data, EPA stove

8. 1.) Pellet Stove PM Repeatability EPA M5G-3 vs Condar Method
Interpretation: Using a shortened version of the ASTM protocol, filters were pulled for each burn rate after approx 1 hr of sampling. With the 2” M5G filters, the catch was very low . The 6” Condar filters have 9X the catch and provide an extra digit of resolution.

9. Pellet Stoves, low filter catch (shortened ASTM method)

10. 2.) Crib Repeatability HeatKit masonry heater, 22” (large) firebox, 1 repeat load
Moisture map for pair of sequential cribs. Test was repeated with a closely matched pair, made from alternate (interleaved) sections of the dimensional lumber stock.
Time lapse – double click to repeat

11. 2.) Crib Repeatability HeatKit masonry heater, 22” (large) firebox

12. 3.) Cordwood repeatability, MHA lab

13. 2 MHA Repeatability Studies Cordwood in a masonry heater 22” firebox, Austrian eco-labelled air system – side ignition

14. 2 MHA Repeatability Studies Cordwood in a masonry heater 22” firebox, Austrian eco-labelled air system – side ignition, W. Birch
Time lapse – double click to repeat

15. 2 MHA Repeatability Studies Cordwood in a masonry heater 22” firebox, Austrian eco-labelled air system – top ignition

16. 2 MHA Repeatability Studies Cordwood in a masonry heater 22” firebox, Austrian eco-labelled air system – top ignition, Red Oak
Time lapse – double click to repeat

17. Side ignition Top ignition Conclusion:
For PM, pellet stoves had 3X better repeatability than a masonry heater fueled with cribs.
Cribs had 1.5 – 2 X better repeatability than carefully matched cordwood loads in a masonry heater.
To get a reliable PM number, cordwood likely will need more repeat runs than cribs.