Can You Use a Rocket Stove Indoors? What is a Rocket Mass Heater?
One of the most common questions we get is, “Can you use your rocket stove indoors?” The simple answer is no, it is an outdoor stove and you want to make sure you have proper ventilation. Still, many people are fascinated by the incredible energy-efficiency of rocket stoves and would like to use that technology to heat their homes. They are looking for a rocket mass heater, powered by the same principles as energy-efficient, clean burning rocket stoves.
Why are Rocket Stoves Energy Efficient? In emergencies, rocket stoves are especially handy because they don’t rely on electricity or fossil fuels like propane. When natural disasters strike they usually leave you without electricity or other types of fuel, thus making it difficult to cook a warm meal for your family, neighborhood, or congregation. However, you don’t need a natural disaster to warrant using a rocket stove for outdoor cooking; rocket stoves allow you to conveniently cook despite the circumstances.
Rocket stoves are very efficient wood burning stoves that are great for outdoor use. But what makes them so efficient? One word: Airflow.
The L-shaped chamber in rocket stoves allows for maximum airflow. Fire needs fuel, heat, and oxygen to burn. Take any of these components away, and your fire will sputter and eventually burn out. The air flow in rocket stoves is particularly important to providing oxygen to the fire. Because rocket stoves are designed to provide the maximum amount of oxygen, the fuel will be burned most efficiently, providing the maximum amount of heat from the fuel.
Can You Use Bear River Rocket Stoves Indoors? Two question that frequently arise are “Can you use Bear River Rocket Stoves indoors?” and, “Because rocket stoves are so efficient in burning, can Bear River Rocket Stoves be used indoors for heating?” The short answer to both questions is no. Bear River Rocket Stoves are designed for outdoor use to ensure proper ventilation.
While rocket stoves burn the renewable fuel more efficiently than most other options, they are typically not properly vented for indoor use. The rocket stoves are built with great circulation to allow for very efficient fuel use, but, as with any outdoor stove, burning outside ensures enough ventilation. The uses any outdoor stove can be put to, far outweigh the fact that they can only be used outdoors.
Rocket stoves are meant to reach very hot temperatures and as such, could be tempting to use as a heat source, especially when electricity or other sources are not available. But, again, proper ventilation is essential. Bear River Rocket Stoves were designed as an outside appliance and work well on the back driveway, under a covered porch, or under a canopy.
But if what you’re really looking for is an indoor rocket heater, you’ll want to read up on rocket mass heaters.
What is a Rocket Mass Heater? Rocket mass heaters work on the same principle as the rocket stoves. However, they have one important difference: Rocket mass heaters are meant for indoor heating by transferring the heat from the stove to a masonry mass (usually formed into a couch or bed). Because heat stores more efficiently in massive stone surfaces than it does air, the heat from the rocket mass heater rests in the mass, warms people who sit on it, and radiates into the room.
Mass heaters are safe for indoors, but do require a permit in most places and extensive knowledge about how to properly vent them. However, people who’ve built them say rocket mass heaters are well worth the effort and report that the heaters use 80-90% less wood to heat the same area with a metal wood stove. You can see why a rocket mass heater would be such a popular and efficient way to heat your home!
For all that, building a rocket mass heater yourself is possible and is even a cost effective and fuel-efficient way to heat a home.
Leslie Jackson and Ianto Evans wrote the book on rocket mass heaters. Literally. Their website, RocketStoves.com, explains how Ianto Evans, a Welsh professor of Landscape Architecture and Ecological Designer, has taken the rocket stove technology and adapted it for in-home heating through rocket mass heaters. An expert in rocket stoves, Evans, has traveled from South America to Africa cooking with the people and studying how to most efficiently heat and cook.
Many people are not fully aware as to what rocket mass heaters are and so many places around the country do not building codes that cover rocket mass heaters. When deciding to build a rocket mass heater, the part of this project that usually tends to stump people is receiving the building permit.
Ernie Wisner, a contributor to the second edition of Rocket Mass Heaters, has worked with Erica Wisner to simplify the building permit process for rocket mass heaters in Portland, Oregon. You can read their story here.
Rocket mass heaters, just like the rocket stoves, can be built by handy do-it-yourselfers. These do, however, tend to be a little more difficult than the rocket stoves. Nonetheless, they can be done by just about anyone with very basic masonry skills. Rocket mass heaters require a J-shaped chamber, a 50-gallon drum or cob. Typically a mix of compressed clay and straw is used for the mass masonry, yet, anything from stone, brick, or tile can be used just as well.
How do Rocket Mass Heaters Work? Remember that in order for a fire to burn it needs three things: Fuel, oxygen, and heat. Like rocket stoves for cooking, rocket mass heaters combine the three elements of fire for optimum fuel use and heat. A rocket mass heater has a J-or L-shaped combustion chamber, which forces the fire to burn horizontally.
The 90-degree angle of the chamber creates a turbulence, which feeds the intensity of the fire and makes it more efficient in its fuel use. The airflow through the chimney of the heater allows maximum oxygen to reach the fire and heats the heater with efficiency and allows less wood to burn as a result. Once the temperature reaches a high enough level, it will burn the combustion gases as well as the wood in order to reduce the pollution. At the end of the burning you are left with just a pile of ashes that are quite easy to clean out and prepare the heater for the next use.
How do I learn more about rocket mass heaters? Here are 4 books that talk about rocket mass heaters: