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Current Heater Testing at Lopez Labs

February 11, 1997

Today, we did run 5 of a 10 run series with a controlled wood load. All pieces have the same moisture content, and are split from hardwood boles between 8" and 14" in diameter. The wood load consists of 8 pieces and 2 lb kindling. The pieces are stacked in a 2-3-3 log cabin configuration. The two top rows are stacked tight, with the bark down (see fuel load photo).

Data is available in Excel format.

We used a Kodak DC-50 digital camera to document the burn progressions. Below are the images from today's test run, which finished at 11:30 a.m.

Today, we replaced the standard loading door with a solid sheet of ceramic glass to get a better view of the fire. There were some glitches with the stacking, and the burn has a few slow spots, and the photographic progression is quite different from yesterday. Efficiency is down about 3% from yesterday

RUN No. HK-f25
Number of Pieces
Total Weight, lb
Wood Moisture %
Fuel Surfac/Vol


Average Stack Temp, F

+/- 0.1

Average O2 %

+/- 0.2

Stack Dilution Factor
g/kg CO
Combustion Efficiency %
Heat Transfer Efficiency %
Overall Efficiency %

+/- 1.5

Average Output, 24 hrs, Kw


2 minutes
5 minutes
10 minutes
15 minutes
1" air slot at bottom
of glass was closed after
this photograph
20 minutes

Spacing is a little loose
on the top row, and
burn will slow in upcoming

25 minutes
30 minutes
40 minutes
50 minutes
Top right piece rolled at
40 minutes and was poked

Note increaced flaming,
spike in stack temperature

60 minutes
70 minutes
80 minutes
90 minutes
100 minutes
Pile fell over at 90 minutes and was poked
Note increased flaming, spike in
stack temperature

Glass temperature: 550F

110 minutes
120 minutes

Test ended at 130 minutes
Still 4 lbs fuel burning.

Compare with yesterday

0 minutes

Also, we are running some bake oven tests on a prototype heater.

In addition to a continuation of the combustion testing we will also be looking at:

Bakeoven Tests

January 18: 10:30 a.m.

We've switched to an infrared thermometer which gives instantaneous surface temperatures with a simple "point and shoot" operation. The graph below shows surface temperature readings for the oven floor, back, ceiling and side. It's -25C outdoors, so we're firing the heater with about 70 lbs. of wood. The last time it was fired was yesterday morning.

Christmas 1996 Tests

This page last updated on April 5, 2003

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