Monday, November 05, 2007

A Sawdust-Burning Stove

I became interested in sawdust-burning stoves when I saw one in a comedor several weeks ago that hadn´t been used for quite a while. The owner said that the neighbors complained whenever they used it because it produced a lot of smoke. It seemed like a really good idea, since sawdust is at least 5 times cheaper than firewood. I decided to see if I could find a less polluting way to burn it. I found a couple different designs on the internet, the most promising one by a former Peace Corps volunteer. It consists of a metal container (recycled can or cylinder) with a hole in the bottom placed on top of a couple of bricks. A tube is inserted into the hole while you fill the container with sawdust and tamp it down. Then you carefully remove the tube, place a sheet metal donut over the top of it and seal the edges with a little sand or dirt. To light it, you just roll up a sheet of newspaper and light the bottom end. To use it as a stove you have to place a couple of metal bars across the top to support the pot. The cylinder I used is about 10 inches wide and 20 inches high. In my version of the stove, I riveted another, larger diameter cylinder to the one containing the sawdust, so that most of the pot sits down inside the cylinder, improving heat transfer to the pot.

I like my wood-burning bread oven and use it a lot. But sometimes I´d like to be doing other things while my bread or cake is baking. If I´m not monitoring it every four or five minutes and adding wood when needed, it´s impossible to maintain a constant temperature. So I´m hoping to use the same principle to convert my oven to use sawdust, too. But in the sawdust stove above, the diameter of the burning sawdust (and hence the surface area) slowly increases as the sawdust is consumed, causing the temperature to rise gradually but significantly. So I´ve built another version of a sawdust burner to use with my oven. It uses the same type of cylinder, but before packing it with sawdust I insert four triangular metal forms, creating four smaller columns of sawdust each with a constant width. I´ve tested it and it seems to burn at a pretty constant temperature. Now I just have to play with the size of the opening and the height of the sawdust column to achieve the particular temperature that I want for baking.

1 comment:

stu said...

do you have any updates on your sawdust stove adventure? very interested..thanks