Rocket stoves are efficient and hot burning stove concepts and products you have doubtless heard about if you’ve been involved in prepping these past few years. I say both products and concepts because rocket stoves are not just an item you buy over the counter to toss in your bob.
Rocket stoves are pretty easily made out of all kinds of common materials and what’s more generate fantastic amounts of heat for very little fuel. Sounds like a winner. So how do they work?
Rocket stoves generate such incredible heat on so little fuel by being incredibly efficient. Compared to a conventional fireplace or wood stove, a rocket stove generates almost no smoke. This is because the particulate we normally see coming off a fire in the form of smoke is actually fully combusted in a rocket stove design.
This is accomplished by the design of the stove: volatile compounds along with a bunch of fresh oxygen are drawn past the fuel chamber and into the horizontal burn tunnel where they combust completely. The resultant heat races into the heat riser, or chimney, where it roars upward to warm or cook whatever is attached to the system.
The adaptable design of rocket stoves is what makes them so compelling and such a great idea for prepping: they work on the small or the large scale, and can be used for cooking, heating and other purposes.
In fact any application were you need a tremendous amount of clean-burning heat using very little fuel compared to other kinds of stoves.
Rocket Stove Design
Understanding the principle behind a rocket stove is almost as important as actually owning one, since you can make your own pretty easily out of commonly available materials.
The most common design of rocket stove looks like a capital letter j when viewed from the side. A short, open vertical riser of the J’s foot is the feed tube, or fuel chamber.
Compared with other stove designs which severely limit the ingress of oxygen, the feed tube of a properly built rocket stove is wide open allowing a tremendous amount of oxygen in to facilitate combustion.
The bottom, horizontal connecting tube of the J is the burn tunnel this is where combustion actually takes place and the flames from the burning fuel crackle.
Those flames will shoot into the opening of the longest vertical member of the j, the heat riser, or chimney, where a tremendous volume of extremely hot air will race upward, rapidly heating whatever is attached to the system to extremely high temperature.
One essential element of the rocket stove design is the thick insulation layer around the entirety of the feed tube, burn tunnel, and heat riser.
This insulation allows for very little heat loss, and in conjunction with a tremendous mass of constantly flowing cooler air is perhaps the rocket stove’s most famous benefit: incredibly high temperature from a small amount of fuel.
A properly designed rocket stove is so efficient a few twigs, yes, twigs, can easily cook a complete dinner or heat an entire room in your house.
The interior lining of the stove is almost always made out of metal of some kind, either sheeting bent into shape or purpose made tubing, and the insulation layer can be made from anything from dirt or clay or heat resistant, man-made material.
“Rocket” Combustion vs. Normal Combustion
Comparing conventional “straight pipe” stoves, ones where the heat riser or chimney is directly over the fuel chamber against the rocket stove we can begin to see the differences and how they support combustion.
When fuel is burned, and in this case we are talking about wood, compounds that are not fully burned are released in the form of particulates that are airborne, what is commonly called smoke or soot.
Smoke is released because in conventional stoves not enough air reaches the burning fuel. This is especially prevalent if the intake is throttled down to its smallest size. If less oxygen reaches the fuel, you have a cooler burn.
A cooler burn means more unburned particulates i.e. more smoke. In this equation that means wasted fuel, and loss of efficiency. Smoke is always associated with fire from long experience with it, but when your fire is burning close to ideally you will have little or no smoke!
This is where a rocket stove leaves a conventional one in the dust. As fuel starts to burn, and the hot air rises through the chimney, incoming cool air moving for the fuel chamber is drawn ever faster into the burning fire.
More incoming air provides for higher temperatures, and more complete combustion, the particulates that would normally make up smoking a conventional stove are burned up in this reaction, providing even more heat and sustaining the reaction until the fuel is consumed.
It is this fact that actually lends the rocket stove its name. The air moves through the stove so quickly a great roaring or whooshing sound, like a rocket, is heard and the flames licking through the burn tunnel appear as the contrail that’s coming out of an airborne rocket engine.
Rocket Stove Advantages
I’m continually surprised that rocket stoves are not more popular in the U.S. than they are already. These systems deserve a place in preppers arsenal’s for several reasons:
- Rocket stoves large and small are easily built from common materials. Various iterations of the design lend themselves to be made from different materials, be they portable versions, or larger fixed versions.
- Rocket stoves can easily produce temperatures well in excess of traditional stoves using drastically less fuel.
- Rocket stoves can make use of wood that would otherwise only be kindling as a primary fuel source.
- Rocket stoves are extremely efficient, offering near complete combustion of their fuel. This makes them clean-burning. Aside from just being efficient, this reduces the signature produced by them when in operation. No smoke, no problem!
- Rocket stoves can be adapted for all kinds of purposes: cooking, heating living spaces, water heating and more.
Rocket stove plans are abundant in print and online. Make sure you take the time to get familiar with this ingenious heating device and add it to your prepping repertoire!
Rocket stoves function by drawing large quantities of air over a relatively small quantity of fuel, burning it almost completely, and then channeling the ever-increasing heat up a large vertical heat riser to whatever device is connected to the end of the system.
These clean and hot burning stoves are marvels of efficiency and are a perfect addition to any prepper’s survival plans.
Tom Marlowe grew up with a gun in his hand, and has held all kinds of jobs in the gun industry: range safety, sales, instruction and consulting, He has the experience in helping civilian shooters figure out what firearms work best for them.
5 thoughts on “How Does a Rocket Stove Work?”
Tom, can a rocket stove be used as the primary heat source for a cabin or house? I’ve seen many rocket stoves designed to heat water or a meal OUTDOORS. But it’s rare or impossible to find a rocket stove designed for INDOOR heat.
Is this b/c of the need to intermintently add fuel/wood to the stove, making it impossible to sleep thru a night w/o waking up to feed the rocket stove?
Or is this b/c of another reason?
The problem with the rocket stove being used as an indoor heat source is more political than anything else. To be insurable, most heating systems need an approval from UL. There hasn’t been a ‘standard’ design that has gone through an approval process. Also there is a mountain of antiquated notions about wood burning devices to overcome. Then there are the environmentalists going nuts over pollution, completely ignoring the evidence that rocket stoves actually burn the pollutants produced. For home heating uses, the rocket stove provides immediate radiant heat as well as heating a large mass of masonry, clay cob, stone, or other dense material which then acts as a heat ‘battery’, radiating heat gradually over a span of many hours. The entire rocket stove/ mass heater concept is fascinating to examine, and YouTube has tons of videos on the subject.
Great article; I was on the School Board for the last 3 years. The weld shop started building these rocket stoves out of 4″x4″ /3/16 steel. The last two years they were up for sale on auction. To help out I started the bids on all the stoves. YEP, no one knew what they were and I ended up with all of them. Being on the school board paid off. Life is good, Ranger Rick, North Idaho
Do you still have any of them? Also close to North Idaho 🙂
I have been studying and use a Rocket Stove for years in my garage. I do wood working in there. This is a great article for a beginner to read. It is not overly complex. As stated, there is a mountain of information on YouTube. Where you can learn about heated secondary air and getting a cyclonic fire. There are places where you can learn to be a “High Tech Red Neck” by learning the formulas. Which you only need if you plan on NASA or SpaceX launching it.