DIY Guide: Create your own rocket stove

Want to create your own rocket stove? Well lets get started! Its simple and we are going to cover how to do so quickly and efficiently. First a little introduction. A rocket stove is nothing more than a highly efficient cook stove that uses a wood fuel source that is generally small in diameter.

The fuel is burned in a sometimes primitive, high heat combustion chamber with a vertical chimney and a secondary air supply generating near complete combustion prior to the flames reaching the cooking surface. In other words you have a high heat, efficient cooking option with a low overall fuel consumption. What’s not to like?

The concept of the rocket stove and the principles that drive is were invented in 1982 by Dr. Larry Winiarski while he was employed by Aprovecho Research Centre as a Technical Director. Rocket stoves can also be implemented as space heaters but my main interest is using one geared around stove use for outdoor cooking so that is what I intend on covering.

 

As I mentioned all rocket stoves have the same characteristics mainly. They all have a firebox at the front of the stove divided into two compartments: one for air and one above it one for fuel. This allows fuel to be added above the air intake of the firebox chamber. Stoves like this are very fuel efficient. They create little smoke. Also heat transfer and loss are extremely efficient. The heat rises and focuses directly on the heating surface above. The heat in the fire chamber moves up in the chimney and the draft created below enables excellent combustion of the fuel source at high temperatures!

Materials Needed:
1.   4 standard cinder blocks

2.   1 open end cinder block

3.   1 steel sheet cut to size for firebox

4.   1 oven rack of sorts

5.   Many small twigs and sticks for fuel source

Thats it. A few cinder blocks. Overall I spent on this project A grand total  $12.50 USD. An inexpensive and excellent way to efficiently cook not only at camp but under times of power loss if no other options are present.

 

One very simple way to create a rocket stove is right out of cinder blocks as mentioned. They can be easily obtained for under a buck a piece at your nearest home improvement store or for free if you have any laying around. With this design you only need five blocks to put this concept together. So lets get started!

I put one together in my backyard in under a half an hour. I have several large maple and ash trees that produce a lot of small twigs and sticks so there was plenty of fuel for me to gather. Or should I say plenty of fuel for my little helper to gather.

 

I had the block stove set up on a concrete slab that I usually have reserved for my grill during better weather. You need an even surface for the blocks to rest on. If you can not use a concrete surface I would recommend grading and leveling the earth with a level and tamping it down a bit so everything is level. After you have a level surface it is time to position the blocks.

 

In the first image you can see the base block and the chamber placed. The blase block is a solid block. The chamber block is the only block you need modify. It needs an open end. I just put a masonry blade on my circular saw and opened up the end.

 

The third block  in the second image completes the horizontal  portion of the chamber as seen with the steel firebox divider. I used a piece of thin steel  to create a firebox and divider. I used two sheets. One to create a divider for two chambers, one chamber being fuel the other air intake.  I used a second sheet on the base of the interior chamber only in hopes to protect the cinderblock a bit longer from the high heat. While inexpensive I hope to extend its usefulness with added reinforcement.

 

After that it is as simple as placing the two blocks on top to complete the vertical chamber.  There you go. All you need now is the stove grate and some fuel and you are cooking! Literally. Please note the size of the fuel. The smaller the twig the better. Now there was some trial and error.

My first attempt while a success was not desirable one. I wanted to see how long it would take to bring 20oz of water to a running boil. I was saddened to find it took over 11 minutes  (11:23) however the elements were against me that day.  Most of my fuel was damp from the rain the night before as I did not cover it properly. In fact I just gathered what I could off of the ground at random that day.

Also my steel container boiler cup I used to boil water was not as wide as I wanted it to be as seen in the final image, leading to even more heat loss through the top chamber.

That coupled with some of my fuel mishaps (twigs were a hair too large and damp) slowed down my heat generation considerably. Lastly, while at my general home improvement store I did not realize that the cinder blocks I purchased were of two different overall shapes.

While very close there were a few cracks that generated even more heat loss.  Still with that said I was not totally unhappy with my boil time. A little helper to aid in adding fuel to the fire never hurts either. I aim to prove the number on my next run. I would imagine if this were at a campsite that lining it with clay would eliminate most of your heat loss and give it a clean and professional look.

I hope this helps. I had fun with it and learned a few things in the process and I hope it aids others. Stay tuned for future updates with more DIY projects.  I hope to update this post in the future with added thoughts and tips on the rocket stove concept we put together.