WOODGAS STOVE, SMALLER VERSION

In my first trial, I made a woodgas stove that was quite large. It worked quite brilliantly and I can easily image myself using it camping. It is quite large and I was wondering if I could make a smaller tin can woodgas stove that worked as well.

Making the smaller wood gas stove

I followed pretty much the same procedure for the small woodgas stove as I had for the larger one

I chose 2 cans so that the smaller one fits well within the larger one with about a quarter inch all around.

I marked the diameter of the smaller can on the bottom of the larger can. It followed a ridge so it was easy to mark. I then made a smaller circle inside the first. I also followed a ridge.

Using an utility knife I cut the smaller circle out. I wore goggles because I've had the knife blade break before.

Using tin snips I cut tabs all around the large can between the small hole and the marked larger circle. It is easier to snap in can if the tabs are cut a bit beyond the marked circle which is the circumference of the small can.

Using a large nail I punched a lot of holes in the bottom of the small can. The bigger the holes the better. I think they are too small in the picture. There are also holes punched around the top rim of the large can (this will actually be at the bottom of the finished stove).

Here are holes at the top of the smaller can. This is where the jets will be formed.

NOTE: After my first test, I went back and made the holes much larger. This had no real effect on how well the stove burned.

The larger can has the tabs cut and I have began bending these backward. I bent most all the way backwards but kept 4 tabs only partly bent to better hold the smaller can in place.

The smaller can fits snugly into the larger can bottom in the woodgas stove assembly.

Once the smaller can has been inserted I screwed in 3 screws that will hold the pot. I am now ready to test out my smaller wood camping stove.

Testing the Smaller Wood Gas stove

I cut out a mittful of wood and split it so it would light easily. Some pieces are about half inch across while others are as small as a matchstick in thickness. 34 grams of wood and about a gram of paper were packed in the woodgas stove

500 ml of quite cold water was measured and put in a small pot with a cover.

I then lit a piece of paper and put the woodgas stove on top of the burning paper. I had to repeat this a couple of times before the paper in the can would light. I put matchsticks under the rim of the stove to increase the air to the bottom but it made no difference. I guess there was enough air getting in. I had trouble lighting it. The larger woodgas stove lit much better. Some people carry a small squirt bottle of alcohol and this helps light the stove.

After a few attempts at lighting the woodgas stove, it finally started burning. The burn was not as good as the large stove but the jet effect developed and at that point the jets were well established and the stove was working quite well.

After 6 minutes I checked the water and it was just on the verge of boiling. The stove burned vigorously for about 6 of the 7 minutes that flames were visible. It took about a minute for the jets to develop. When flames went down I looked in and found some glowing charcoal at the bottom.

The wood did NOT completely burn and charcoal was left. The large Woodgas stove had burned completely leaving only a bit of ash. The bottom holes were not blocked so air was available. I'm wondering if the small size of the stove meant that it was not capable to produce enough heat to keep going. It is just below freezing now and the larger stove was tested in late spring when it was warmer. There was also a bit of wind that had a larger effect than on the larger stove.

I could have had a windbreak and it would have helped. In both my woodgas stove test I used quite cold water from the tap. I think the temperature was quite similar.

Conclusions on smaller Woodgas Stove Experiment

The smaller stove worked but not as well as the larger stove.

• It was harder to light even though the wood was very dry had been split smaller.
• Once the wood had lit the jet effect developed and it heated quite well
• Smaller stove was more sensitive to small wind. A windbreak would be useful.
• Very cold water was near boiling after 6 minutes, probably boiled before flames went down. So the 35 grams of fuel boiled 500 mils of water after 7 minutes.
• Woodgas stove went out before all the fuel was used up. Some charcoal was left behind.
• I think the smaller stove is not as easy to use and is more sensitive to air temperature and wind. I might have had better result with larger punched holes on the bottom of the smaller can (NOTE: I tried this later and it made no real difference). I could not have added much more fuel at the start, so capacity is not really that practical. The woodgas stove worked and boiled the water but was harder to use.
• Some of the more successful smaller stoves have little blowers to force air into the stove. Here is one design Gas stove with Blower. Here are instructions for another stove Stove PDF instructions file

Here are links to some successful woodgas stoves available comercially.

• Solo Stove & Pot 900 Combo: Ultralight Wood Burning Backpacking Cook System. Burns Twigs.
• Kelly Kettle Stainless Steel Medium Scout Basic Camp Stove Kit.
• Solo Stove - Wood Burning Backpacking Stove - Ultra Light Weight Compact Design.
• Bushbox Outdoor Pocket Stove
• Wild Woodgas Stove

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This web site reflects my personal ideas and doesn't represent anyone else's point of view.