The cob rocket stoves we built last year were our first try with the cob. They worked pretty well, but we wanted to try and make them even better this year. Here goes:
The rocket stove that we built out of fire bricks worked wonderfully. It cost $60 though. In order to get this same, efficient design for free, I decided to build the cob rocket stove just like the brick one. Except I wanted 3 burners.
I used the bricks to make a, sort of, mold for the stove. I left a brick in the center where the hole in the stove will be and built the cob around it.
Since the “bridge” over the opening is what crumbled last year, I added an old tin can for support. Cut off the top and bottom of the can, then cut it down the middle and flatten it out. I also bent the ends down so it couldn’t breal loose from the clay with a lot of use.
Another area that broke down with use was the back of the sove where the moving sticks in the fire dug through. I took an old tuna can with the top removed. Then I cut off half of the sides and bottom to make an insert to protect the back of the stove. (sorry for the lousy pic on this one. I am stuck using a cell phone camera)
Then I piled up the cob all around the base until it was as tall as the fire brick rocket stove.
I never got a picture of the finished stoves before we started using them. The two on the right are much more well used than the one on the left, to get an idea of the difference.
Again, the stove on the right has had much more use. You can tell because the side are all crumbling in. They do still work though. Next year, I will have to add a little more tin can support to the sides so that this will not happen. The stoves wear out over the winter some anyway, so they will need to be rebuilt anyway.
Overall, these rocket stoves have been awesome. I don’t even mind that I have to rebuild them every year. It just means they are being improved all the time.
And once you build the stove, get the T-shirt!