Rocket oven with stove bench. Will it flare up and take off? Rocket furnace: what is it, its features, device drawings

A simple heating device, which is not much inferior to a potbelly stove in popularity, is a rocket stove. It works on wood, and the design scheme is so simple that it is possible to manufacture it on your own. The stove can also be made economical - many people think that looking like a potbelly stove means the voracity of the combustion chamber, but no. There are schemes that work on smoldering wood (pyrolysis), which means that they are economical with the same efficiency.

Why rocket and why jet

Such a stove is often called a “rocket”, but not because the firewood in it burns at high speed, but because of the shape of the structure - the traditional version of the rocket stove is made from two pieces of iron pipes welded together. The unit resembles a rocket in a child's drawing. The use of a simplified form allows you to make it in less than a day. The adjective “reactive” is also used for the stove, but also not because of the speed of fuel combustion, but because of the characteristics of combustion - at a certain stage of air supply to the firebox, it starts to hum strongly, as if turbocharging of the nozzles in the engine is turned on.

Furnace humming is an inefficient and consumable combustion mode. During normal operation, it emits a quiet rustle.

Any owner of a country or country house has at least a minimal set of carpentry, plumbing and automotive repair tools in his workshop. So they will help in the manufacture of a miracle rocket, plus blueprints and a minimum supply of materials: pipes or metal boxes, a sheet of iron and - in the construction of a stationary version - brick and mortar on clay. Now it becomes clear that the jet stove is made portable or stationary, for example, for heating a house or a bath.

If a stationary jet stove will heat the house, then it is located along the outer wall. Properly designed and equipped, it can heat a house up to 50m2. Also, the stove is installed in an open area - on a personal plot, and is used as a summer option for cooking.

How does a rocket stove work?

The device is the simplest - two principles of fuel combustion borrowed from other furnaces:

1. The natural circulation of hot gases and smoke through the channels of the stove is a standard solution, as in a potbelly stove.
2. Afterburning of unburned gases (pyrolysis) with limited access of oxygen to the combustion chamber.

The scheme of the simplest jet stove, which is intended only for cooking, uses the natural combustion of firewood - in an open chamber it is impossible to create conditions for maintaining the pyrolysis reaction and afterburning unburned gases.

Let's consider a simple design of a direct burning rocket stove, which is traditionally installed in the yard in an open area. It can quickly heat water or cook dinner for the family on vacation. From the figure below, it becomes clear that such a sample will require two pieces of a cylindrical or rectangular iron pipe, which are interconnected by welding at an angle of 90 0.

A horizontal segment of a metal box acts as a combustion chamber - firewood is laid there. Also, fuel loading can be organized vertically - add a vertical iron cylinder on top of a horizontal pipe for loading firewood. Thus, a structure of three pipes or boxes will be obtained, the lowest of which (horizontal) will work as a firebox. In a stationary scheme, the simplest stove design often uses red brick, which is placed on clay mortar.

The efficiency of the design cannot be called satisfactory, so the craftsmen figured out how to increase the efficiency of its work. An additional element is another pipe of a larger diameter (as you can see, all materials are available and cheap), into which the main pipe of the riser stove (primary chimney) is installed. This increases the overall heating and the duration of heat retention.

On the diagram:

1. Outer body.
2. A pipe that serves as a firebox.
3. Channel for air outlet to the combustion chamber.
4. Insulated area between hull and riser. The same ash can serve as a heater.

How to heat

The Robinson jet stove is heated according to the principle of kindling a fire - paper, hay, straw or other quickly combustible material is laid first, then small chips or large chips. The last logs are laid in the size of the firebox. Hot combustion products rise along the vertical pipe (2) and go outside. On the open end of the pipe (2) you can put a pot or a tank of water.

In order for the fuel to burn continuously and actively, it is necessary to provide a gap between the outlet pipe (2) and a pot of water using a special lattice metal stand.

The diagram below shows a simple device with a door on the fuel loading hole. Air draft is formed due to the presence of a special channel formed by the lower surface of the furnace and an iron plate welded 8-10 mm from the combustion chamber. This design will forcibly pump air even if the door closes completely. It can be seen from the diagram that the design is also designed for operation in the pyrolysis mode, while a constant flow of a “secondary” air jet will burn out the exhaust gases. But in order for the afterburning to take place at 100%, it is necessary to equip the thermal insulation of the secondary chamber in which the gas burns out in order to provide the necessary temperature indicators for pyrolysis.

On the diagram:

1. Forced channel for blowing air with the furnace door closed.
2. Area of ​​active combustion.
3. burnt gases.

The improved scheme provides not only the possibility of heating the surrounding space, but also cooking, for which the upper hob is designed. In total: to the simplest version of the “rocket”, you can add an outer case, which will additionally heat the room, the furnace door, blowing air to maintain the pyrolysis mode and a stove for cooking food. This scheme can already be implemented in the house itself, and not in the yard, since the chimney pipe is brought out. Such a minor upgrade significantly increases the efficiency of the model. So, a do-it-yourself rocket stove, the drawings of which are presented below, has the following capabilities:

1. Due to the embedding of the outer casing of a larger diameter pipe and its insulation, which creates a thermal insulation layer for the riser, as well as the ability to hermetically close the top pipe, the hot air cools down much longer.
2. A separate blowing channel has been added in the lower section of the stove, which allows organizing pyrolysis combustion.
3. The chimney in such a scheme is recommended to be placed not vertically at the top, but from the bottom at the back of the case, which will allow organizing additional circulation of hot streams through the internal channels of the stove, ensuring rapid heating of the hob and the entire insulated case.

In the firebox (1), the fuel does not burn completely (2), since the air supply is not carried out in full, this is the “A” mode, which can be controlled using the damper (3). Hot, but not burnt out from pyrolysis, gases are fed into the end section of the fire channel (5), in which they are burned. Afterburning provides high-quality thermal insulation and a constant flow of "secondary" air in the "B" mode through the channel (4).

The hot stream then enters the inner riser (7), rises up to the cooking plate (10) and heats it up. Further, hot air enters the volume (6) between the outer and inner pipes, insulated with a layer of ash (4, 9), heats the furnace body, which gives off heat to the room. Finally, the cooled air descends to enter the chimney (11) and exit.

Consistently high temperature in the riser (7) provides maximum heat transfer and creates conditions for complete combustion of gases due to the placement of the riser in a larger pipe - shell (8). The free space is filled with ash or other heat-resistant substance (9) for lining - it can also be a solution of ordinary clay with sand in proportions of 1:3.

The palm of popularity belongs to the industrial model "Robinson" - this is a simple but reliable design. Having such a mobile stove, you can quickly cook food or heat water in the country or on a hike. Structurally, this is an inverted L-shaped pipe, as shown in the diagrams below.

Firewood is laid in the horizontal section of the fuel receiver, and ignition is carried out from the side from which the vertical pipe enters. In the L-shaped pipe, due to the pressure difference between hot and cold air, draft arises, and the intensity of combustion will only increase as the furnace body heats up. The air supply is controlled by a damper.

The furnace works on the principle of energy consumption of the natural flow of hot gases. It turns out a closed cycle: as the temperature rises, the fuel begins to burn more actively and the chamber and hob heat up faster. As a result, "Robinson" is able to heat 10 liters of water in 10 minutes, if you put the tank on an already warm surface. The diagram shows that the hob in the "Robinson" has a thick heat-insulating layer, which allows you to put large diameter chocks into the firebox.

Stationary oven

Stationary models have a cap to keep the heat in the room longer. In such a stove, fuel combustion occurs according to a different scenario. The beginning of the process of burning wood is the same - the air supply is limited. This causes the release of pyrolysis gases, which are afterburned in the lower section of the vertical pipe or duct, where the secondary air is supplied separately.

The hot gas, once at the top, begins to cool and descends into the free inter-chamber volume, and then into the chimney. It happens like this:

1. Gravitational forces cause the colder, and therefore heavier, burnt gases to rush down, where they enter the chimney.
2. This is facilitated by the constantly maintained pressure from the firewood and the consistently high temperature of the gases.
3. Natural draft in the chimney.

All this creates effective conditions for the combustion of firewood and it becomes possible to attach a smoke channel with arbitrary geometry to the "rocket". Basically, long and complex chimneys are needed in order to better heat the room.

The main disadvantage of all solid fuel stoves is the inability to keep most of the heat in the house. But the positive qualities make it possible to neutralize the negative points - the high rate of gas outlet allows you to organize complex vertical or horizontal chimneys with several channels. The implementation of this principle in practice is the Russian stove. In a jet furnace with a horizontal multi-channel chimney, it is also possible to equip a warm bench, as shown in the diagram below.

A jet rocket stove is a variant of home heating, which is cheaper only for nothing. A person familiar with the basics of construction can fold a combined brick oven in a design suitable for any home interior. The main task of ennobling the appearance will be decorating the iron cap and the lid of the firebox - everything else will not be visible.

Combined brick-metal barrel oven

It is stationary, because the structure cannot be moved. A fuel chamber and a chimney are laid out of fireclay bricks, valves and doors are made of metal. The brick gives off heat very slowly, so the room will be warmed for a long time.

High efficiency is not the strong point of such models, but good heat transfer can be achieved by adjusting the air supply to the chamber, without trying to enter the combustion mode, in which the stove begins to “roar” and “buzz”.

In order to somehow minimize heat losses during the operation of this simple design, many craftsmen build a water circuit into the oven and connect a hot water tank. Also, the construction of a stove bench with a multi-channel horizontal chimney contributes to the preservation of heat in the room. Negative qualities of "rocket" models that cannot be minimized or removed:

1. It is necessary to constantly monitor and adjust the thrust - there are no automation devices.
2. Every 2-3 hours you need to load a new portion of firewood.
3. The iron cap heats up to dangerous temperatures.

The simplest and cheapest option is the Robinson model, which is shown in the drawing below. For its manufacture, you need trimming pipes or a rectangular profile box, metal corners for legs, a welding machine. Its dimensions are selected based on the dimensions of the blanks. The main thing is to adhere to the principle of action, not size.

For a home-made design, gas cylinders or barrels of 200 liters are often taken - thick walls and a suitable size are the best fit for what was intended. Both those and others are used to make the outer case, and the internal elements are made from pipes of a smaller diameter or are brought out with bricks - halves, quarters or whole.

There is no general formula for calculating heat transfer for all models of a rocket stove, so the option of using ready-made calculations based on the principle of similarity of circuits is quite suitable. The main thing is that the size of the future "rocket" should at least approximately correspond to the volume of the heated room. For example, a gas cylinder will do for a garage, a two-hundred-liter barrel for a country house. An approximate selection of internal elements is shown in the diagram below.

Iron bottle stove

1. Cylinder - gas, oxygen, from under carbon dioxide.
2. Pipe ≥ 150 mm for fuel and loading chambers.
3. Pipes 70 and 150 mm - for an internal vertical chimney.
4. Pipes 150 mm - for the outlet chimney.
5. Insulation of any type, necessarily non-combustible.
6. Sheet metal blanks H = 3 mm.

The upper part of the cylinder is cut off by welding. For safety reasons, it is better to open the stopcock on it and fill it with water before cutting. From the sides, you need to cut openings for the fuel chamber and chimney. The pipe for the firebox is connected to the vertical pipe of the chimney channel from the bottom of the cylinder.

After mounting the internal elements, the cut top is welded back. The seams are checked visually, the main chimney is connected. If there is a water circuit, it also joins. After that, the rocket oven can be tested.

Sufficient draft is provided by the height of the chimney - it must be raised above the firebox by at least 4 meters.

How to lay out a brick firebox

Such a model requires the use of only fireclay (clay) bricks - ceramic or silicate will immediately crack. Masonry is carried out on clay mortar, the proportions of the composition are indicated above. A pit is dug under the base of the stove, the soil at the bottom is rammed and poured with concrete. The size of the foundation is 1200x400x100 mm.

After the base has hardened, it is protected with a sheet of basalt cardboard, then they begin to lay out the firebox, vertical chimney and loading chamber. A door for ash removal is attached to the front of the firebox. After the clay mortar dries, the trench is filled up, a pipe of the desired diameter is inserted into the vertical chimney. The cavities between the brick and the pipe should be filled with insulation - basalt wool, ash or other non-combustible material, such as asbestos.

Now a cap Ø 600 mm is placed on the masonry - a cut-out cover from a metal barrel will do. Before installation, a hole is cut out in it, into which the pipe for the chimney is inserted. Putting on this cap, the barrel should be turned over, and the nozzle will be where it is needed. Then the chimney is brought out - either directly to the street, or through the arrangement of a lounger with horizontal chimney channels. The lounger can be laid out with ordinary silicate bricks, since the temperature of the gases will already be low.

A practical heating device that is not inferior in its functionality to a traditional potbelly stove is a rocket stove. Its demand lies in high efficiency, economy, availability of design and ease of manufacture. Even novice craftsmen can assemble such a unit at home.

What is a Rocket Oven?

The jet furnace got its original name due to the special design of the body - the traditional form of the device is made from cuts of metal pipes interconnected by a weld. Outwardly, it resembles a rocket launcher. A simplified model of the furnace can be assembled in a few hours.

The heater becomes reactive as a result of the peculiarities of the combustion process of the fuel material, when at a certain moment of operation, with a high supply of air mass to the fuel chamber, the stove begins to create a powerful hum and vibration.

Important! The buzz mode of the rocket furnace is characterized by irrational fuel consumption in the process of its combustion. The economical heating mode ensures quiet operation of the heating unit.

Principle of operation

Despite the fact that the rocket oven is quite simply arranged, its principle of operation is based on the following processes:

• Natural circulation of heated gases and air inside the channels. This means that the device does not require additional blowing, and the internal draft is created by a flue system. The higher the chimney, the stronger the draft.
• Afterburning of waste gases (pyrolysis process) is carried out with a slight supply of oxygen to the fuel chamber. It provides a rapid increase in the efficiency of the device and the efficient consumption of fuel material in the combustion process.

The process of heating the furnace itself is carried out as follows:

1. Firewood is placed in the fuel compartment, and ignition is performed.
2. Next, the standard operating mode of the furnace is set, in which the complete heating of the vertical part of the structure - the chimney pipe - is carried out.
3. Sufficient heating of the furnace body provides ignition of volatile substances in the chimney and rarefaction of air in its upper part.
4. Natural draft increases, which leads to air flow into the fuel compartment and an increase in the efficiency of the combustion process.
5. To maintain complete combustion of the fuel material, the furnace design must be equipped with a special zone for afterburning pyrolysis gases.

A simple version of a rocket stove made of a profile pipe is intended for cooking and heating food, as well as for heating garden houses, summer cottages and camping baths.

Advantages and disadvantages

The long-burning rocket furnace has gained particular popularity and demand due to its positive characteristics:

• Affordable design and easy assembly. The simplest version of the oven can be made at home from available materials in a few hours.
• Efficient heat transfer using various types of wood fuels - firewood, wood chips, twigs, bark and shavings.
• Wide functionality. Possibility of using the device for space heating, cooking and water heating.
• Complete combustion of fuel with the possibility of afterburning pyrolysis gases. This allows you to increase efficiency and at the same time avoid carbon monoxide poisoning.
• Possibility of refilling fuel without interrupting the work process.
• No need to create forced draft in the chimney system. High level of self-regulation of operating modes of the device.

The ergonomic stove can be installed in any room, and lightweight construction does not require additional arrangement of a reinforced foundation.

Despite the significant advantages, such a unit is not without some disadvantages:

• The lack of the possibility of automating the furnace process. Homemade stoves require constant human control over the laying of fuel material.
• High probability of getting burns with significant heating of the metal structure.
• The device is not intended for heating large residential buildings and stationary bath complexes.
• The stove is designed to use well-dried fuel, since excess moisture can lead to back draft in the chimney.
• Unaesthetic appearance of the finished device.

Design

The rocket-type stove is represented by a fairly simple design, which is made from pipes of the required diameter.

The fuel chamber is a horizontal pipe section into which fuel is loaded. In some cases, the oven may have a vertical loading option. In this case, the device consists of three structural elements - two vertical pipes of different heights, mounted on a horizontal pipe. The short section of the pipe is the fuel compartment, the long section is the chimney.

To ensure an increase in efficiency, rocket furnaces may have additional structural elements:

• Fuel compartment (vertical or horizontal position) - for loading fuel.
• Afterburner (horizontal) - for fuel combustion and thermal energy accumulation.
• Blower compartment - for afterburning pyrolysis gases, which are formed during the combustion of fuel.
• The outer casing of the furnace is for thermal insulation of the structure.
• A lounger is a platform for resting in a lying or sitting position.
• Chimney pipe - to remove the products of combustion of fuel and create natural draft.
• A hob is a horizontal platform for cooking or heating water.

DIY manufacturing

A home-made stove from a spent gas cylinder is an affordable option for a wood-burning stove, which is designed for efficient space heating and economical fuel consumption.

To make an oven at home, you will need:

• Empty cylinder body - 2 pcs.
• Metal pipe for creating a vertical chimney channel (diameter - 12 cm).
• A profile pipe for the manufacture of a firebox and a loading chamber (length 100 cm, cross section - 12 × 12 cm).
• Cuts of metal pipes: short by 80 cm (diameter - 15 cm) and long by 150 cm (diameter - 12 cm).
• Steel sheet (thickness 3 mm).
• Metal rods.
• Warming heat-resistant material (perlite).
• Welding equipment.
• Bulgarian.
• Personal protective equipment - goggles and gloves.

To ensure the correct assembly of the furnace, it is recommended to prepare a working drawing indicating the exact dimensions of all structural elements of the device.

Step-by-step instructions for making a rocket furnace:

1. Three segments are cut from the profile pipe - two of them are 30 cm each and one for a sunbed by 35 cm. A rectangular hole for the fuel compartment and a semicircle for a vertical pipe are made from a blank for a sunbed by a grinder.
2. One 30 cm blank is cut lengthwise and welded to the fuel chamber to create an air channel.
3. The fuel compartment is connected to the pipe by hot welding.
4. A grate is made from fittings, for a fuel chamber and an ash pan - doors.
5. Next, a secondary chamber for afterburning pyrolysis gases is manufactured.
6. A hole is made at the bottom of the cylinder for the fuel compartment. On the outside of the cylinder, a knee is fixed under a pipe with a diameter of 12 cm for the chimney.
7. A hole is cut at the bottom of the pipe to clean the chimney.
8. A piece of pipe with a diameter of 15 cm is mounted on top of the pipe and welded to the cylinder by welding.
9. The free space between the two pipes is filled with insulation, the edges are closed with a weld.
10. In the second cylinder, the bottom is cut off and a hole for the valve is welded. It will be used for afterburning pyrolysis gases.
11. Both cylinders are fixed to each other in a special groove using two welded rings so as to ensure the tightness of the finished structure. The groove is sealed with asbestos cord.

Important! Before starting to fire a home-made rocket stove, it is necessary to carefully check the quality of the connecting seams and the tightness of the structure. Air masses must not penetrate uncontrollably into the operating installation.

How to properly fire a rocket?

To obtain the maximum heating effect, the rocket-type furnace should be thoroughly heated before the main laying of the fuel material. For this, flammable materials are used: paper, wood chips, dry shavings, sawdust, cardboard, reeds or straw, which are placed in an open blower compartment.

Warming up the system will lead to the appearance of a characteristic sound - a quiet or loud buzz. Further, the main fuel is loaded into the heated device to obtain the required amount of thermal energy.

The firing process itself is carried out according to the following scheme:

• Opening the door to the blower compartment.
• Bookmark fuel material to maintain the optimum combustion temperature.
• With the appearance of a hum in the furnace, the blower closes until the moment of complete transition to the silent mode of operation.

Important! If a closed air damper has led to a decrease in the intensity of the flame, it must be opened in order to increase traction and intensify the combustion process of the fuel.

Other types of rocket stoves

Based on the basic design of the rocket stove, other variants of heating devices with a higher efficiency were created, which are intended for outdoor use and internal operation as a source of heating and hot water supply.

Stove-stove

The device is designed for cooking and winter preservation, equipped with an extended cooking surface designed for several containers.

A distinctive characteristic of the rocket stove is that the vertical channel with the fuel chamber is located in the lower part of the cooking surface. In this case, hot air from the furnace quickly heats the surface, and in order to keep the stove hot as long as possible, fuel gases accumulate inside the horizontal channel. The remains of the gas mixture are discharged into a vertical smoke channel connected at an angle to the hob.

For ease of use, the oven is equipped with stable supports, so it can be easily used on any surface, both indoors and outdoors.

Stove with water circuit

Such a unit is equipped with a heat exchanger, which is connected to the heating system: radiators, pipes and a water tank. It is designed to create a complete autonomous heating system for a small garden or country house.

Structurally, the stove consists of the following functional elements:

• The vertical fuel compartment and the brick fire channel are laid out on a solid concrete base. At the bottom of the structure there is an ash pan with a door for removing ash.
• Vertical steel channel with a heat-insulating gasket, protected by an outer metal casing.
• Heat exchange unit with a water circuit mounted on a metal casing.

A distinctive feature of the furnace is the creation of a water jacket, when a liquid heat carrier circulates through the pipes instead of air, providing efficient space heating.

Stove with stove bench

Another option for using a jet stove in everyday life is the arrangement of a convenient design with a special platform for relaxing in a sitting or lying position. The lounger can have a different form of execution - a trestle bed, a wide bed, a compact sofa, a bench.

Brick, rubble stone, clay mass with sawdust are used to make the stove bench. The high heat capacity of materials contributes to the accumulation of thermal energy for a long time, so it is recommended to install such a stove in living rooms.

According to the type of material used for the manufacture of the structure, rocket furnaces are:

• Clay-brick. The good heat capacity of bricks and fireclay clay contributes to the fact that such structures accumulate well and release heat into the room. The temperature regime of fuel combustion in such furnaces can reach 1000 degrees. Clay-brick units require minimal maintenance, which consists in periodically coating the body with clay and eliminating cracks.
• Metal . Such devices are made of metal barrels, gas cylinders, fire extinguishers, pipes and sheet steel. The availability of materials allows you to get a reliable and efficient heating unit. Camping metal stoves - "Robinson", "Ognivo" or "Taiga" are especially popular. They are compact in size, can be installed anywhere and are easy to use.
• From improvised materials. Simplified designs of rocket ovens can be made from the cheapest and most affordable materials: cans, steel buckets and other containers. Low-power stoves can be used to quickly heat water in the field.

A mobile stove is a practical and cheap option for hiking and outdoor recreation, which is designed for economical fuel consumption and ease of use in any climatic conditions.

A stationary stove is an efficient and safe option for heating small areas, organizing hot water and cooking.

For all its merits, a do-it-yourself reactive furnace design is not suitable as a full-fledged heat source for heating a residential building. But to use the technical capabilities of the device to solve everyday problems is quite acceptable.

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Let's say right away: rocket stove - a simple and convenient heating and cooking device for wood fuel with good, but not exceptional parameters. Its popularity is explained not only by the catchy name, but more so by the fact that it can be made with your own hands and not by a stove-maker or even a bricklayer; if necessary - literally in 15-20 minutes. And also by the fact that, having invested a little more work, you can get an excellent couch in the house without resorting to the construction of a complex, expensive and cumbersome or. Moreover, the very principle of the device of the rocket furnace gives great freedom to design and the manifestation of creative abilities, see fig.

But perhaps more remarkable is the "jet furnace" by the huge number of associated, at times completely absurd inventions. Here, for example, are a few pearls snatched at random:

• "The operating principle of the furnace is the same as that of the MIG-25 ramjet engine." Yes, the MIG-25 and its descendant MIG-31 did not sit down near the ramjet engine (ramjet), as they say, and did not sit down in the bushes. On the 25th and 31st there are bypass turbojet engines (turbojet engines), four of which then pulled the Tu-144 and still pull other cars. And any furnace with any jet engine (RD) is technical antipodes, see below.
• "Reverse jet furnace". Is this a tail-first stove, or what?
• “But how will she blow such a pipe?” A naturally aspirated stove does not blow into the chimney. On the contrary, the chimney pulls out of it, on natural draft. The higher the pipe, the better it pulls.
• “The rocket stove is a combination of a Dutch bell-type stove (sic!) with a Russian stove bench.” Firstly, there is a contradiction in the definition: a Dutch oven is a channel oven, and any bell-type oven is anything but a Dutch oven. Secondly, the couch of the Russian stove warms up in a completely different way than the rocket stove.

Note: in fact, the rocket stove was nicknamed so because in the wrong mode of the furnace (more on that later), it emits a loud whistling rumble. A properly tuned rocket stove whispers or rustles.

These and similar inconsistencies, of course, are confusing and prevent us from making a rocket furnace properly. So let's figure out what is true about the rocket stove, and how to use this truth correctly so that this really good stove shows all its advantages.

Furnace or rocket?

For complete clarity, we still need to figure out why a stove cannot be a rocket, and a rocket cannot be a stove. Any RD is the same internal combustion engine, only the outflowing gases themselves act as pistons, connecting rods with a crank and transmission. In a piston internal combustion engine, already at the moment of combustion, the high temperature of the working fluid creates a large pressure that pushes the piston, and it already moves the entire mechanics. The movement of the piston is active, the working fluid pushes it to where it tends to expand itself.

When fuel is burned in the RD combustion chamber, the thermal potential energy of the working fluid is immediately converted into kinetic energy, like that of a load falling from a height: since the exit to the nozzle is open to hot gases, they rush there. In RD, pressure plays a subordinate role and nowhere exceeds a few tens of atmospheres, this, for any conceivable nozzle cross section, is not enough to disperse a flashlight to 2.5M or put a satellite into orbit. According to the law of conservation of momentum (momentum), the aircraft with RD at the same time receives a push in the opposite direction (recoil momentum), this is jet thrust, i.e. thrust from recoil, reactions. In a turbofan engine, the second circuit creates an invisible air shell around the jet. As a result, the recoil momentum is, as it were, contracted in the direction of the thrust vector, so the turbofan is much more economical than a simple turbofan.

In the furnace, there is no conversion of types of energy into each other, therefore it is not an engine. The stove simply distributes the potential heat energy properly in space and time. From the point of view of the furnace, the ideal RD has an efficiency of 0%, because it just runs on fuel. From the point of view of a jet engine, the furnace has an efficiency = 0%, it only dissipates heat and does not pull at all. On the contrary, if the pressure in the chimney rises to or above atmospheric (and without this, where will the jet thrust or active force come from?), The stove will at least smoke, or even poison the residents or start a fire. Draft in the chimney without pressurization, i.e. without the expenditure of energy from the side, it is provided due to the temperature difference along its height. Potential energy here, again, is not converted into any other.

Note: in a rocket-propelled rocket engine, fuel and oxidizer are fed into the combustion chamber from tanks, or they are immediately filled into it if the rocket engine is on solid fuel. In a turbojet engine (TED), the oxidizing agent - atmospheric air - is injected into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes a certain fraction of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it takes 80-90% of the power of the jet, which is transmitted to the propeller and compressor. In a ramjet engine (ramjet), air is supplied to the combustion chamber by hypersonic velocity pressure. A lot of experiments were carried out in the ramjet, but there were no production aircraft with it, there is not and is not expected, the ramjet is painfully capricious and unreliable.

Can or not can?

Among the myths about the rocket stove, there are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the "racquet" with the Chinese kan.

As a child, the author had a chance to visit the Amur region, in the region of Blagoveshchensk, in winter. There were a lot of Chinese there in the villages even then, who were scrambled in all directions from the cultural revolution of the Great Chairman Mao and his completely frostbitten hungweibins.

Winter in those parts is not Moscow, frost at -40 is a common thing. And what struck and aroused interest in stoves in general was how Chinese fanzes were heated by kans. In Russian villages, firewood is transported by carts, smoke is a pillar from the chimneys. And all the same, in the log hut, not in a children's girth, by morning the corners were frosted over from the inside. And the fanza is built like a country house (see the figure), the windows are covered with a fish bladder or even rice paper, bunches of chips or twigs are placed in the kan, but the room is always warm.

However, there are no subtle heat engineering tricks in the canal. This is an ordinary, only small, stove with a lower exit to the chimney, and most of the chimney itself is a long horizontal channel, a hog, on which a stove bench is arranged. The chimney, for the sake of fire safety, is outside the building.

The effectiveness of the kan is determined primarily by the thermal curtain it creates: the couch goes around, if not the entire perimeter from the inside, except for the door, then 3 walls for sure. Which once again confirms: the design and parameters of the furnace must be linked to those of the heated room.

Note: The Korean ondol oven operates on the principle of a warm floor - a very low stove bench occupies almost the entire area of ​​​​the room.

Secondly, in the very cold, the Kans were drowned with argal - dried droppings of ruminants, domestic and wild. Its calorific value is quite high, but argal burns slowly. In fact, an argal fire is already a long-burning stove.

It is not in the Russian custom to stick twigs into the oven every now and then, and our peasants abhorred cooking on animal feces. But travelers of the past highly valued argal as a fuel, collected it along the way and carried a supply with them, diligently protecting it from getting wet. N. M. Przhevalsky, in one of his letters, argued that without the argal, he could not have carried out his expeditions in Central Asia without loss. And for the British, who were disdainful of the argal, 1/3-1/4 of the personnel of the detachments returned to the base. True, he was recruited from sepoys, Indian soldiers in the English service, and pandits - spies recruited from the local population. One way or another, but the highlight of the rocket stove is not at all in the couch on the hog. To get to it, you will have to learn to think in an American way: all the primary sources on the rocket furnace are from there, and utter speculation is generated only and only by misunderstanding.

How to deal with rockets?

From our point of view, one should study the original technical documentation of rocket furnaces with caution, but not at all because of inches-millimeters, liters-gallons and the subtleties of American technical jargon. Although they also mean a lot.

Note: a textbook example is "Naked conductor runs under the carriage". Literary translation - a naked conductor runs under the car. And in the original article from Petroleum Engineer, it meant "Bare wire runs under the crane trolley."

The Rocket Oven Was Invented by Members of Survival Societies- people with a peculiar way of thinking, even by American standards. In addition, they were not bound by any standards and norms, but, like all Americans, they always automatically converted everything into money, taking into account their own benefit; a person with a different worldview in America simply does not get along. And instinctive self-interest inevitably gives rise to egocentrism. He by no means excludes good deeds, but not out of a spiritual outburst, but out of the calculation of dividends. Not in this life, but in that one.

Note: How much the average inhabitant of the greatest empire in history is afraid of everything can be understood only after talking with them long enough. And sociopsychologists go out of their way there, convincing that living, languishing in fear, is normal and even cool. The rationale is clear: intimidated biomass is easily predictable and manageable.

Without heating and cooking, of course, you will not survive. What is an oven for? For the time being, for the time being, the survivors were content with camping stoves. But then, according to the Americans themselves, in 1985-86. they were greatly impressed by two films that were released with a short interval and triumphantly went around all the screens of the world: the Soviet science fiction parody of the entire human race "Kin-dza-dza" and Hollywood's "The Day After", about the global nuclear war.

The survivors realized that after the nuclear winter there would be no extreme romance, but there would be the planet Plyuk in the Kin-dza-dza galaxy. It will be necessary to be content with the newly appeared plukans "ka-tse" in small quantities, bad, expensive and difficult to access. Yes, all of a sudden someone hasn’t watched “Kin-dza-dza” - like a match in Plukansky, a measure of wealth, prestige and power. It was necessary to invent your own furnace, none of the existing ones is designed for a post-nuclear spit.

Americans are very often endowed with a sharp mind, but a deep one is found as the rarest exception. A completely normal and with an IQ above the average, a US citizen may sincerely not understand how it doesn’t reach another that he himself has already “caught up” and how someone else may not like what suits him.

If an American has already understood the essence of an idea, then he brings the product to its possible perfection - what if there is a buyer, you can’t sell raw iron. But the technical documentation, which looks beautiful and neat, can be drawn up in fact extremely carelessly, or even deliberately distorted. And what is it, this is my know-how. Maybe I'll sell it to someone. Whether there will be a plus, or not, but for now the know-how is worth the money. In America, such an attitude to business is considered quite honest and worthy, but there a clinical alcoholic at work will never miss a stopper and will not drag a couple of bolts home to the farm. On that, in general, the whole of America stands.

And the Russian breadth of the soul is also a double-edged sword. Most often, our master simply understands from a sketch how this thing works, but in the details it turns out to be careless and overly trusting in the source code: how is it for a crafty brother to deceive his own. If you don't have something, then you don't need it. It seems clear how everything is spinning there - already my hands itch. And there, perhaps, until it comes to a hammer, chisel and related literature, still count and count. Moreover, important points can be omitted, veiled or deliberately wrong.

Note: An American acquaintance once asked the author of this article - how did we, the really stupid ones, elect the very smart Reagan as president? And you, really smart, tolerate a slobbering senile with dyed eyebrows in the Kremlin? True, then in America no one in a bad dream would have imagined that in the next century a black citizen with a Muslim name would settle in the Oval Office, and his first lady would dig a garden near the White House and grow turnips there. Times is changing, as Bob Dylan once sang for a completely different reason ...

Sources of misunderstanding

There is such a thing in technology - the square-cube law. Simply put, when something changes in size, its surface area changes squarely, and its volume changes cubed. Most often, this means that changing the overall dimensions of the product according to the principle of geometric similarity, i.e. You can't just keep the proportions. With regard to solid fuel stoves, the square-cube law is doubly valid, because fuel is also subject to it: it releases heat from the surface, and its reserve is contained in the volume.

Note: a consequence of the square-cube law - any specific design of the furnace has a certain allowable fork of its size and power, within which the specified parameters are provided.

Why, for example, can not be made the size of a refrigerator and a power somewhere that way at 50-60 kilowatts? Because the potbelly stove, in order for it to somehow warm, must itself be heated inside to at least 400-450 degrees. And in order to warm up the volume of the refrigerator to such a temperature at a given heat transfer, firewood or coal needs as much as it does not fit in it. There will also be no sense from a mini-potbelly stove: the heat will leave through the outer surface of the furnace, which has grown relative to its volume, and the fuel will not give it away more than it can.

The square-cube law acts triple on the rocket furnace, because she is "licked" in an American professional way. With our kondachka, it is better to stay away from her. Here, for example, here in Fig. American development, which, judging by its demand, many of our craftsmen take as a prototype.

With the fact that the exact grade of refractory clay (fire clay) is not indicated here, ours will sort it out. But, to be honest, who noticed that, judging by the absence of an external chimney and the presence of transportation holes (carrying pipe), this stove is mobile with an open firebox? And most importantly, the fact that a 20-gallon keg with a diameter of 17 inches (431 mm with change) went to her drum?

Judging by the structures from Runet, no one at all. They take this thing and adjust it according to the principle of geometric similarity to a domestic 200-liter barrel with a diameter of 590 mm on the outside. Many guess to arrange a blower, but the bunker is left open. Are the exact proportions of vermiculite with perlite for lining the riser and forming the furnace body (core) not specified? We make the lining homogeneous, although it will be clear from what follows that it should consist of insulating and accumulating parts. As a result, the furnace roars, the fuel eats only dry, and a lot, and even before the end of the season, it overgrows with burning inside.

How was the rocket oven born?

So, already without science fiction with futurology, the survivors needed high-efficiency home heating stove with low-quality random wood fuel: wet wood chips, twigs, bark. Which, moreover, will need to be reloaded without stopping the furnace. And most likely it will not be possible to dry in a firewood shed. Heat dissipation after heating needs at least 6 hours to get enough sleep; getting pissed off in a dream on Pluka is no better than in America. Additional conditions: the design of the furnace should not contain complex metal products, non-metallic materials and components that are required for the manufacture of production equipment, and the furnace itself must be available for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics and other energy dependencies.

They immediately took a couch from the kan, but what about the fuel? For a bell-type furnace, it requires high quality. Long-burning furnaces work even on sawdust, but only dry, and do not allow shutdown with additional loading. Nevertheless, they were taken as a basis, they were very attracted by the high efficiency achieved by simple methods. But in an attempt to make the "long stoves" work on bad fuel, another circumstance became clear.

What is wood gas?

High efficiency is achieved largely due to the afterburning of pyrolysis gases. Pyrolysis is the thermal decomposition of solid fuel into volatile combustible substances. As it turned out (and the survivors have their own research centers with highly qualified specialists), the pyrolysis of wood fuel, especially wet fuel, continues for a long time in the gas phase, i.e. The pyrolysis gases that have just been released from the wood still require quite a lot of heat to form a mixture that can burn out completely. This mixture was called wood gas, woodgas.

Note: in RuNet, woodgas has created more confusion, because in American vernacular, gas can mean any fuel, cf. e.g. gas station - gas station, gas station. When translating primary sources without knowing the American technical, it turned out that woodgas is just wood fuel.

Before that, no one saw wood gas: in conventional furnaces, it is formed immediately in the furnace, due to the excess energy of fiery combustion. The designers of long-burning stoves came to the conclusion that the primary air must be heated, and the exhaust gases should be retained in a significant volume over a large mass of fuel, simply by trial and error, so they overlooked the wood gas.

It turned out not so when firing with bundles of twigs: here the primary pyrolysis gases were immediately dragged into the chimney. Wood gas could have formed in it at some distance from the furnace, but the primary mixture had cooled by that time, pyrolysis stopped, and heavy radicals from the gas settled on the walls of the chimney like soot. Which quickly tightened the channel completely; amateurs building rocket furnaces at random are well familiar with this phenomenon. But the survivors eventually figured out what was going on and made the right oven anyway.

Who are you, the Rocket Stove?

There is an unspoken rule in technology: if it seems that it is impossible to create a device according to the given requirements, then read, smart guy, school textbooks. That is, go to the basics. In this case, to the basics of thermodynamics. Survivors do not suffer from sick pride, they turned to the basics. And they found the main principle of operation of their furnace, which has no analogues in others: slow adiabatic post-combustion of pyrolysis gases in a low flow. In long-burning furnaces, afterburning is equilibrium isothermal, requiring a large buffer volume, subject to the square-cube law, and the energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but practically into free volume. And now - learn to think in an American way.

How does a rocket oven work?

The scheme of the final fruit of the labors of the survivors is presented on the left side of fig. Fuel is loaded vertically into the bunker (Fuel Magazine) and burns, gradually settling down. Air enters the combustion zone through the blower (Air Intake). The blower must provide an excess of air so that it is enough for afterburning. But not excessive, so that the cold air does not cool the primary mixture. With vertical loading of fuel and a blind cover of the bunker, the flame itself acts as a regulator, however, not very effective: when it flares up too much, it pushes the air out.

Further things already non-trivial begin. We need to warm up, and with good efficiency, a large stove. The law of the square-cube does not allow: the meager heat will immediately dissipate so much that the pyrolysis will not reach the end, and the thermal gradient from the inside to the outside will not be enough to transfer heat into the room; everything will whistle through the trumpet. This law is harmful, you can't break it in the forehead. Okay, let's see in the basics, if there is anything there that is not subject to him.

But how, there is. That same adiabatic process, i.e. thermodynamic without heat exchange with the environment. There is no heat exchange - the squares are resting, and the cubes can be reduced even to a thimble, even to a skyscraper.

Imagine a completely isolated volume of gas. Let's say it releases energy. Then the temperature and pressure will begin to rise until the energy release stops, and will freeze at a new level. Great, we burned the fuel completely, hot flue gases can be released into a heat exchanger or heat accumulator. But how to do it without technical difficulties? And most importantly - how, without violating the adiabat, to supply air for afterburning?

And we will make the adiabatic process non-equilibrium. How? Let the primary gases immediately from the combustion source go into a pipe covered with high-quality insulation with a low intrinsic heat capacity (Insulation). Let's call this pipe for ourselves a flame or a burning tunnel (Burn Tunnel), but we will not sign it (know-how! You can’t catch up - give money for consulting drawings! Without theory, of course. Who sells the fixed capital at retail.) On the diagram, so that not accused of "opacity", denoted by the flame.

Along the length of the flame tube, the adiabatic index changes (this is a non-equilibrium process): the temperature will first drop slightly (wood gas is formed), then it will increase sharply, the gas will burn out. It is possible to release it into the accumulator, but we forgot - what will pull gases through the flame tube? Supercharging means energy dependence, and there will be no exact adiabat, but something mixed with an isobar, i.e. the efficiency drops.

Then we will lengthen the pipe by half, keeping the insulation so that the heat does not go in vain. We bend the “idle” half up, making the insulation weaker on it; how to keep the heat seeping through it, we will think a little later. In a vertical pipe, a temperature difference will appear along the height, which means thrust. And good: the thrust force depends on the temperature difference, and with an average in the flame tube of about 1000 degrees, it is not difficult to achieve a difference of 100 at a height of about 1 m. So, while we have made a small economical potbelly stove, now we need to think about how to use it warmly.

Yes, it does not interfere with additional encryption. If we call the vertical part of the flame tube the primary or internal chimney (Primary or Internal Vent), then they will guess the main idea, we are not the smartest in the world. Well... let's call the primary chimney the most common technical term for vertical pipes with upward current - the riser (riser). Purely American: correct and incomprehensible.

Now let's recall the heat transfer after heating. Those. we need a cheap, always available and very capacious heat storage. There is nothing to invent here, the adobe (Thermal Mass) was invented by the primitives. But it is not fire resistant, it does not hold more than 250 degrees, and we have about 900 at the mouth of the riser.

It is not difficult to convert high-potential heat into medium-potential heat without loss: you need to give the gas the opportunity to expand in an isolated volume. But, if the expansion is left adiabatic, then the volume will need to be too large. And that means - material and labor intensive.

I had to bow to the basics again: immediately after leaving the riser, let the gases expand at constant pressure, isobarically. This requires heat to be removed to the outside, about 5-10% of the heat output, but it will not disappear and will even be useful for quickly warming up the room during the morning fire. And further along the course of gases - isochoric cooling (in a constant volume); Thus, almost all the heat will go into the battery.

How to do it technically? We cover the riser with a thin-walled iron drum (Steel Drum), which will also stop heat loss from the riser. The “drum” turns out to be a bit high (the riser sticks out a lot), but it doesn’t matter: we will cover it with the same adobe for 2/3 of the height. We attach a stove bench with an airtight chimney (Airtight Duct), an external chimney (Exhaust Vent), and the stove is almost ready.

Note: the riser and the drum covering it look like an oven hood over an elongated hail. But the thermodynamics here, as we see, is quite different. It is useless to try to improve the bell-type stove by building on a high loft - only the extra material and work will go away, and the stove will not get any better.

It remains to solve the problem of cleaning the channel in the couch. For this, the Chinese have to break the kan from time to time and remake it, but we are not in the 1st century. BC. we live when kan was invented. We will arrange a secondary ash pan (Secondary Airtight Ash Pit) with a sealed cleaning door immediately after the drum. Due to the sharp expansion and cooling of flue gases in it, everything in them that did not burn out immediately condenses and settles. The cleanliness of the external chimney is guaranteed by this for years.

Note: the secondary cleaning will have to be opened once or twice a year, so you don’t have to fool around with the latches. We will simply make a cover from a metal sheet on screws with a mineral cardboard gasket.

small rocket

The next task of the designers was to create on the same principle a small continuous combustion oven for cooking in the warm season. In the heating season, the drum cover (Optional Cooking Surface) of a large oven is suitable for cooking, it heats up to about 400 degrees. The small rocket stove was supposed to be portable, but it was permissible to make it with an open firebox, because. when warm, you can cook outdoors or under a canopy.

Here the designers took revenge on the square-cube law, forcing it to work for themselves: they combined the fuel tank with the blower, see Fig. at the beginning of the section on the right. It is impossible to do this in a large furnace, fine adjustment of the furnace mode as the fuel settles (see below) will be impossible.

Here, the volume of incoming primary air (Primary Air) turns out to be small relative to the heat release area, and the air can no longer cool the primary mixture until pyrolysis stops. Its supply is regulated by a slot in the cover of the hopper (Cover Lid). The 45-degree hopper optimizes the oven's auto-adjustment for standard cooking routines, but it's harder to make.

Secondary air for afterburning wood gas in a small oven enters through additional holes in the mouth of the riser or simply flows under the burner if there is a cooking vessel on it. If a small furnace is close to the limit size (about 450 mm in diameter), then an optional secondary woodgas frame may be needed for complete afterburning.

Note: it is impossible to supply secondary air to the mouth of the riser of a large furnace through the holes in the drum (which would increase the efficiency of the furnace). Although the pressure in the entire gas-smoke path is lower than atmospheric pressure, as it should be in the furnace, flue gases will be emitted into the room due to strong turbulence. Here their kinetic energy, harmful to the furnace, affects; this, perhaps, is the only thing that makes a rocket stove related to a jet engine.

The small rocket stove has revolutionized the class of camping stoves, especially camping stoves. A wood chip stove (a Bond stove in the West) will help to cook a stew or wait out a snowstorm in a one-two-man tent, but it will not save a group caught on a spring campaign by a belated bad weather. A small rocket furnace is only a little larger, it can be quickly made from nowhere, but is capable of developing power up to 7-8 kW. However, we will talk about furnace-rockets from anything we will talk further.

Also, the small rocket oven has spawned many improvements. For example, Gabriel Apostol provided it with a separate blower and a wide bunker. The result was a stove suitable for the device of a compact and rather powerful water heater, see the video below. The large rocket furnace was also modified, we will talk about this a little at the end, but for now let's dwell on more significant things.

Video: a water heater based on a rocket stove designed by Gabriel Apostol

How to fire a rocket?

A rocket furnace with long-burning furnaces has a common property: you need to run them only on a warm pipe. For a small one, this is not essential, but a large one on a cold chimney will only burn fuel in vain. Therefore, a large rocket furnace, before loading regular fuel into the bunker after a long break in the furnace and kindling, must be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open blower. The end of acceleration is judged by a change in the tone of the hum of the furnace or its subsidence. Then you can load fuel into the bunker, and its ignition will occur by itself from the accelerating fuel.

The rocket furnace, unfortunately, does not apply to furnaces that are completely self-adjusting to the quality of the fuel and external conditions. At the beginning of regular fuel combustion, the blower door or the bunker cover in the small furnace is fully opened. When the stove hums strongly, cover it "to a whisper." Further, in the process of burning, it is necessary to gradually cover the access of air, guided by the sound of the stove. Suddenly, the air damper slammed shut for 3-5 minutes - it's okay, if you open it, the stove will flare up again.

Why such difficulties? In the process of burning the fuel, the flow of air into the combustion zone increases. When there's too much air, the furnace roars, but don't get excited: the excess air now cools the primary gas mixture, and the sound is amplified as the steady swirl in the riser clumps into a clump. Pyrolysis in the gas phase is interrupted, no wood gases are formed, the furnace consumes too much fuel, and carbon deposits from the soot cemented by bituminous particles are deposited in the riser. This, firstly, is a fire hazard, but most likely it will not come to a fire, the riser channel will quickly overgrow with soot completely. And how to clean it if you have a non-removable drum cover?

In a large furnace, a spontaneous change of regime occurs abruptly, when the top of the sticks drops to the bottom edge of the bunker, and in a small furnace, gradually, as the fuel mass settles. Since an experienced housewife does not leave her for a long time when cooking on the stove, the designers considered it possible, for the sake of compactness, to combine a bunker with a blower in it.

With a large oven, this trick will not work: a high riser pulls very strongly, and the air gap is needed so thin (and it also needs to be regulated) that it is impossible to achieve a stable furnace mode. It’s easier with a separate blower: the mass of fuel, rounded in section, is easier for air to flow around from the sides, a too-flamed flame pushes it there. The stove turns out to some extent self-regulating; however, within very small limits, so you still have to manipulate the blower door from time to time.

Note: for the sake of simplicity, it is impossible to make a bunker of a large furnace without a tight lid, as is often done. Due to the unregulated additional air flow through the fuel mass, it is unlikely that it will be possible to achieve a stable operation of the furnace.

Materials, dimensions and proportions, lining

Now let's see what a home-made rocket stove should be from the materials available to us. Here, too, we need to look back: not everything that is at hand in America is also with us, and vice versa.

Of what?

For a large stove with a bench, more or less reliable experimental data is available for products with a drum from a 55-gallon drum with a diameter of 24 inches. 55 gallons is 208-plus liters, and 24 inches is almost exactly 607mm, so our 200-litre is fine without additional conversion. Keeping the parameters of the furnace, the diameter of the drum can be halved, up to 300 mm, which makes it possible to make it from 400-450 mm tin buckets or a household gas cylinder.

Pipes of different sizes will go to the blower, bunker, firebox and riser, see below, round or shaped. So it will be possible to make an insulating lining of the furnace part from a mixture of equal parts of furnace clay and fireclay crushed stone, without resorting to brickwork; we will talk about the riser lining in more detail below. Combustion in the rocket furnace is weak, therefore the thermochemistry of gases is gentle and the thickness of the steel of all metal parts, except for the gas pipeline in the stove bench, is from 2 mm; the latter can be made from thin-walled metal corrugated, here the flue gases have already completely exhausted both in terms of chemistry and temperature.

For external coating, the best heat accumulator is adobe. Subject to the dimensions indicated below, the heat transfer of a rocket furnace in adobe after combustion can reach 12 hours or more. Other parts (doors, covers) are made of galvanized metal, aluminum, etc., with sealing gaskets made of mineral cardboard. Conventional oven fittings are not suitable enough, it is difficult to ensure their tightness, and a slotted rocket oven will not work properly.

Note: it is desirable to equip the rocket furnace with a view in the external chimney. Although the gas view in the high riser seals the common smoke path tightly, strong winds outside can prematurely draw heat out of the couch.

Dimensions and proportions

The basic calculated values ​​to which the rest are tied are the drum diameter D and its cross-sectional area along the inside S. Everything else, based on the size of the available iron, is determined as follows:

1. Drum height H - 1.5-2D.
2. Drum coating height - 2/3H; for the sake of design, the edge of the coating of the design can be made oblique curvilinear, then 2/3H must be maintained on average.
3. The thickness of the coating of the drum is 1/3D.
4. The cross-sectional area of ​​the riser is 4.5-6.5% of S; it is better to stay within 5-6% of S.
5. The height of the riser - the larger the better, but the gap between its edge and the drum tire must be at least 70 mm; its minimum value is determined by the viscosity of the flue gases.
6. The length of the flame tube is equal to the height of the riser.
7. The cross-sectional area of ​​the flame tube (fire pipe) is equal to that of the riser. It is better to make a fire pipe from a square corrugated pipe, so the furnace mode will be more stable.
8. The cross-sectional area of ​​the blower is 0.5 from its own firebox and riser. A more stable furnace mode and its smooth adjustment will be provided by a rectangular corrugated pipe with sides 2: 1, laid flat.
9. The volume of the secondary ash pan is from 5% of the initial volume of the drum (excluding the volume of the riser) for a furnace from a barrel to 10% of it for a furnace from a cylinder. Interpolation for intermediate drum sizes is linear.
10. The cross-sectional area of ​​the external chimney is 1.5-2s, where s is the cross-sectional area of ​​the riser.
11. The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is considered from its lower point. If the bench is on wooden floors, the pillow under the chimney can be halved.
12. The height of the bed coating above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. It can be less, but then the heat transfer after heating will be shorter.
13. The height of the external chimney is from 4 m.
14. Permissible length of the flue in the couch - see next. sec.

The maximum thermal power of a barrel rocket furnace is approximately 25 kW, and a gas cylinder furnace is about 15 kW. Power adjustment - only by the size of the fuel load. By supplying air, the oven is put into operation, and nothing more!

Note: in the original survivalist furnaces, the riser cross section was taken as 10-15% S, based on very wet fuel. Then, in the same place, in America, rocket stoves with a stove bench for a bungalow appeared, designed for air-dry fuel and more economical. In them, the riser section is reduced to the recommended ones and here 5-6% S.

Riser lining

The efficiency of the rocket furnace largely depends on the thermal insulation of the riser. But American lining materials, alas, are not available to us. In terms of stocks of high-quality refractories, the United States has no equal, where they are considered strategic raw materials and are sold with caution even to proven allies.

Of our available materials for heat engineering, they can be replaced with light fireclay bricks of the ShL brand and ordinary self-digged river sand with a large admixture of alumina, correctly laid, see below. However, these materials are porous, in the oven they are quickly saturated with soot. Then the stove will roar with any air supply, with all the consequences. Therefore, we need to surround the riser lining with a metal shell, and be sure to cover the end of the lining with furnace clay.

Lining schemes for 3 types of furnaces are shown in fig. The bottom line here is that with a decrease in the size of the drum, the proportion of its direct heat transfer through the bottom and the unlined part increases according to the square-cube law. Therefore, while maintaining the desired thermal gradient in the riser, the lining capacity can be reduced. This makes it possible to correspondingly increase the relative cross section of the annular descent of the flue gases in the drum.

What for? Firstly, the requirements for an external chimney are reduced, since the outer traction pulls better now. And since it pulls better, then the permissible length of the hog in the stove bench falls more slowly than the dimensions of the furnace. As a result, if a stove from a barrel warms up a bench with a pine forest up to 6 m long, then half the size from a cylinder is 4 m.

How to line with sand?

If the riser lining is fireclay, then the remaining cavities are simply covered with building sand. River self-digging for lining entirely of sand does not need to be carefully prepared, it is enough to select large debris. But they pour it in layers, in 5-7 layers. Each layer is compacted and sprayed until a crust forms. Then the whole backfill is dried for a week, the upper edge is covered with clay, as already mentioned, and the construction of the furnace is continued.

balloon rocket

From the foregoing, it is clear that it is more profitable to make a rocket stove: less work, fewer unsightly parts in sight, and the stove bench warms up almost the same. A thermal curtain or underfloor heating in Siberian frost will heat a room of 50 square meters with a power of 10-12 kW. m or more, so here, too, a balloon rocket turns out to be more profitable, it is rarely necessary to launch a large barrel at full power with maximum efficiency.

Craftsmen, apparently, also understood this; at least some. For example, here in Fig. - drawings of a balloon furnace-rocket. On the right is the original; the author, it seems, was wisely versed in the initial developments and, in general, everything turned out right for him. On the left - the necessary improvements, taking into account the use of air-dry fuel and warming up the couch.

A fruitful idea is a separate supply of heated secondary air. The furnace will be more economical and the flame tube can be made shorter. The cross-sectional area of ​​its air duct is about 10% of the riser cross-section. The furnace always works with the secondary fully open. First, the mode is set with a primary valve; finely adjust the hopper cover. At the end of the furnace, the furnace will roar, but here it is not so scary; the author of the design provides for a removable drum cover to clean the riser. She, of course, should be with a seal.

Rockets from anything

Canned

Tourists, hunters, and fishermen (many of them members of survival societies) soon converted the small rocket stove into a camping stove made from empty tins. It was possible to reduce the influence of the square-cube to a minimum by applying a horizontal fuel supply, see the diagram on the right. True, at the cost of some inconvenience: the sticks need to be pushed inward as they burn out. But the furnace mode began to hold iron. How? Due to the automatic redistribution of air flows through the blower and over / through the fuel. The power of a jar rocket furnace is in the range of 0.5-5 kW, depending on the size of the furnace, and is regulated by approximately three times the amount of fuel loading. The basic proportions are also simple:

• The diameter of the combustion chamber (combustion chamber) is 60-120 mm.
• The height of the combustion chamber is 3-5 of its diameters.
• The cross section of the blower is 0.5 from its own combustion chamber.
• The thickness of the thermal insulation layer is not less than the diameter of the combustion chamber.

These proportions are very approximate: changing them by half does not prevent the stove from working, and the efficiency in the campaign is not so important. If the insulation is made of wetted sandy loam, as described above, the joints of the parts can simply be smeared with clay (left pos. in the figure below). Then the stove, after 1-2 fires, will acquire strength, allowing it to be transported without any special precautions. But in general, any of the improvised non-combustible materials will do the insulation, next. two pos. A burner of any design must provide a free flow of air, 3rd pos. A rocket stove welded from a steel sheet (right pos.) with sand insulation is twice as light and more economical than a potbelly stove of the same power.

brick

We will not expand on large stationary rocket furnaces: in them all the initial thermodynamics goes to pieces, and they are deprived of one of the main advantages of the original furnace - ease of construction. We will talk a little about rocket stoves made of bricks, clay or stone fragments, which can be made in 5-20 minutes when there are no tins at hand.

Here, for example (see the video below), is a completely thermodynamically complete rocket stove of 16 bricks laid dry. The voice acting is English, but everything is clear without words. A similar one can be folded from fragments of bricks (see Fig.), Cobblestones, fashioned from clay. For 1 time, a stove made of greasy earth is enough. The profitability of all of them is not so hot, the height of the combustion chamber is small, but it’s enough for pilaf or urgently to warm up.

Video: 16 brick rocket oven (eng)

new material

Of domestic developments, the Shirokov-Khramtsov rocket furnace deserves attention (see the figure on the right). The authors, not caring about survival in a plus, used a modern material - heat-resistant concrete, adjusting all thermodynamics to it. The components of refractory concrete are not cheap; a concrete mixer is needed for mixing. But its thermal conductivity is much lower than that of most other refractories. The new rocket furnace became more stable, and it became possible to release some of the heat outside in the form of infrared radiation through heat-resistant glass. It turned out a rocket stove - a fireplace.

Do rockets fly in the bath?

Isn't a rocket stove suitable for a bath? It seems to be possible to arrange a heater on the drum cover. Or flowing instead of a couch.

Unfortunately, the rocket oven is not suitable for a bath.. To get light steam, it must immediately warm up the walls with thermal (IR) radiation, and immediately, or a little later - air, by convection. To do this, the oven must be a compact IR source and a convection center. The convection from the rocket furnace is distributed, and it gives little IR at all, the very principle of its design eliminates significant radiation losses.

In conclusion: rocket stove-makers

In successful designs of rocket furnaces, there is still more intuition than precise calculation. And therefore - good luck to you too! - a rocket oven is a fertile field for craftsmen with a creative streak.

To date, quite a lot of varieties and models of wood-burning stoves have been developed and implemented. In this series, the do-it-yourself rocket furnace built with your own hands, the drawings of which will be presented below, fully justifies all expectations. Such a heating structure, of course, deserves close attention, as it has some specific advantages that are indispensable in certain conditions.

This version of the wood stove is simple and original in design and does not require a large number of expensive components and materials for the manufacture. Probably anyone can install such a stove, making it on their own, even if they have no experience in the construction of such structures, but who can read the provided drawings and work with some tools.

It is interesting to note that, if necessary, a rocket stove can be made even in 20–30 minutes, for example, from an iron can. However, if you make every effort, then it is possible to get a comfortable stationary structure for your home with a heated bench that can even replace an ordinary sofa.

The principle of operation of the rocket oven

The rocket stove was originally conceived as one of the functional survival items in difficult conditions. Therefore, its design had to meet certain criteria:

• Efficient space heating.
• Possibility of cooking.
• High efficiency of the device when using various wood fuels of any quality for heating.
• The ability to report fuel without stopping the combustion process.
• In addition, the stove had to keep warm for at least 6-7 hours to enable the owners to spend the night in comfortable conditions.
• Maximum safety of the structure, in terms of eliminating the possibility of carbon monoxide seepage into the room.
• Another condition that had to be met was the simplicity and accessibility of the design for its manufacture by any non-professional.

Therefore, the basis was taken basic principles several types of heating appliances operating on wood solid fuels:

• Free circulation of heated air and gases through all channels. The furnace works without forced blowing, and the chimney creates draft, which draws out the products of combustion. The higher the pipe is raised, the more intense the thrust in it.
• The principle of afterburning the gases released during combustion from the fuel (pyrolysis), which is used in long-burning devices. This principle of operation is extremely important due to the high efficiency of the device, which is achieved by creating special conditions for the afterburning of pyrolysis gases for the most complete consumption of the energy potential inherent in the fuel.

The term "pyrolysis" means the decomposition of solid fuel into volatile substances, under the influence of high temperatures and simultaneous "oxygen starvation". Under certain conditions, they are able to burn out, also releasing a large amount of thermal energy. At the same time, it is important to know that the pyrolysis of insufficiently dried wood takes a rather long time in the gas phase, that is, the released pyrolysis gas will require a lot of heat to create a mixture (wood gas) that can burn completely. Therefore, it is not recommended to use wet fuel for the rocket stove.

A variety of rocket stoves - from simple to complex

The simplest design of a rocket furnace

In a simple design of a rocket stove, heated by bundles of branches or torches, the combustion products almost immediately go into the chimney, without having time to form combustible wood gas in the stove body, so it will not be possible to heat the room with it. Such ovens can only be used for cooking. This model is manufactured in stationary and mobile versions; only the principle of free circulation of heated air operates in it, since it does not create the required conditions for a full-fledged pyrolysis process.

In such furnaces, a small section of pipe is used as a fuel chamber. It can have a horizontal position, as shown in the diagram, or be turned up. In the latter case, fuel is loaded vertically.

After igniting the fuel placed in the pipe, the heated gases released from it rush up the vertical section of the pipe to the outside.

On top of the vertical pipe and install containers for cooking or heating water. In order for the gases to freely escape to the outside, and the bottom of the tank does not completely block the draft in the pipe, a special metal stand is installed on top of the stove. She creates a gap of the right size, which helps maintain traction.

Above - a very original stand for a container of heated water

By the way, this simplest type of furnace device was invented first, and because of the furnace opening turned upwards and the flame escaping from it, the furnace most likely got the name rocket. In addition, if the furnace mode is incorrect, the structure emits a whistling “rocket” rumble, but if the furnace is set up correctly, it rustles quietly.

Advanced Rocket Furnace

Since, using the simplest rocket stove with a free exit of gases, it is impossible to heat the room, the design was later supplemented with a heat exchanger and smoke ducts.

After the improvements made, the whole principle of operation of the rocket furnace has changed somewhat.

• To maintain a high temperature of heated air in a vertical pipe, they began to insulate it with a fire-resistant material, and then close it on top with another metal case made from a larger diameter pipe or a metal barrel with a closed top.
• A door was installed on the opening of the furnace, and a separate channel for secondary air appeared in the lower part of the furnace. Through it, blowing began to be carried out (necessary for the afterburning of pyrolysis gases), which previously occurred through an open firebox.
• In addition, the chimney was moved to the lower part of the hull, which forced the heated air to circulate throughout the hull, bypassing all internal channels, and not escaping directly into the atmosphere.

• The high-temperature combustion products first began to rise to the ceiling of the outer casing, accumulate there and heat it up, which made it possible to use the outer horizontal surface as a hob. Then, the gas flow cools down and goes down, turns into a knee and only from there goes into the chimney.
• Due to the inflow of secondary air, afterburning of gases occurs at the end of the lower horizontal channel, which significantly increases the efficiency of the furnace. The free circulation of gases creates a self-regulating system that limits the flow of air into the combustion chamber, since it is supplied only as the hot gases cool down under the “ceiling” of the housing.

A very popular scheme - from a metal profile and an old gas cylinder

The stove model shown in the figure works like a “potbelly stove” and has a chimney brought out to the street. However, it is unsuitable for use in residential premises, since in it, with changes in external pressure, a reverse draft may occur, which will contribute to the entry of carbon monoxide into the premises. Therefore, such a stove should always be supervised, and it is most often used for heating utility rooms or a garage.

Rocket stove with warm bed

According to the principle of afterburning pyrolysis gases, a rocket furnace with a bench is also arranged, but in this embodiment, the heat exchanger is a structure of combined long channels coming from the furnace and laid or formed from non-combustible plastic materials under the stove bench surface.

It should be noted that such a heating system is by no means new, and, in fact, such a rocket stove has a rather rich history. It was invented a long time ago, presumably in Manchuria, called " kan", and is still traditional for peasant houses in China and Korea.

Similar stoves called "kan" have long been used to heat homes in East Asia.

The system is a wide couch made of stone, brick and clay, inside which the air heated in the furnace passes through the arranged channels, which are essentially an elongated chimney. Passing through this labyrinth and gradually giving off heat, the gas flow, cooling down, exits into a chimney 3000 ÷ 3500 mm high, located on the street, next to the house.

The stove itself is located at one end of the bench and, as a rule, is equipped with a hob, which allows it to be used for cooking.

From above, the stone-clay construction "kan" is covered with straw or bamboo mats, or a wooden flooring is arranged there. At night, the couches were used as beds, and during the day - in the form of a seat, on which, traditionally for Asian peoples, a special low table 300 mm high was installed - a meal was held behind it.

This heating system is quite economical in terms of fuel consumption, since it is enough to use an average thickness of a branch to heat it. Such a rocket stove is able to retain heat for a long time, creating comfortable conditions for sleeping throughout the night.

And Korean stoves "ondol" probably became the prototypes of modern "warm floors"

Korean homes use a heating system similar to " kan", which is called "ondol". This heating option, unlike the Chinese one, is not arranged inside the couch, but under the entire floor of the house. In principle, it can be argued that this method of transferring and distributing heat to residential premises seems to have formed the basis for the design of the modern "warm floor" system.

Furnace design with connected pipes to it can be clearly seen in the diagram presented.

In our time, with today's rich variety of materials, the channels in this design of the furnace can be made of metal pipes laid in the form of a coil and well insulated with non-combustible materials. Therefore, the last section of the chimney system can exit from the structure of the stove next to the stove itself or at the end of the stove, and then go through the wall into the chimney installed on the street.

On the presented diagram, you can see the results of the design work, which made it possible to achieve a relatively simple circuit with a high efficiency, as well as meeting all the requirements for a speech rocket.

Fuel is loaded into the furnace hole vertically. Then it is set on fire, and, burning out, gradually settles down. The air that supports combustion enters the bottom of the combustion chamber through an opening that plays the role of a blower. It must provide sufficient air flow for the afterburning of the released products of the thermal decomposition of wood. But, at the same time, there should not be too much air, since it can cool the initially released gases, and in this case the process of afterburning the pyrolysis gases will not be able to take place, and the combustion products will settle on the walls of the housing.

In this variant, the top-loading furnace has on the furnace chamber blank cover, which eliminate the risk of gases entering the room when creating reverse thrust.

In a completely isolated volume of released gas, thermal energy is generated, temperature and pressure increase, and thrust increases. As the fuel burns, the burning gases go through the channels of the furnace body into the heat exchanger, heating the internal surfaces along the way. Since the channels have a complex configuration, gases are retained inside the furnace for a longer time, giving off heat to the body and channel surfaces, which in turn, they heat the surface of the couch and, accordingly, the room itself.

Over time, any furnace and its channels require cleaning from soot deposits. In this design, the problem area is the heat exchanger pipes located inside the bench. In order to carry out these preventive measures without problems, at the level of the heat exchanger turning from the furnace body into the pipes under the bench, a hermetically closing cleaning door is installed (indicated in the diagram as “Secondary Airtight Ash Pit”). It is in this place that all the unburned products of the thermal decomposition of wood concentrate and settle. The door is periodically opened and the passages are cleaned of soot - this process guarantees long-term operation of the chimney. In order for the door to close tightly, asbestos gaskets must be fixed to its inner edges.

How to properly heat a rocket stove?

To get the maximum heating effect, it is recommended to heat up the furnace before laying the bulk of the fuel. This process is carried out using paper, dry shavings or sawdust, which are ignited in a firebox. When the system warms up, it will change the emitted sound - it may die out or change its tone. The main fuel is placed in the heated unit, which will ignite from the heat already created by heating.

Any firewood and even thin branches are suitable for a rocket stove, but the main thing is that they are dry.

Until the fuel flares up well, the door of the combustion chamber or blower must be kept open . But only when the fire becomes intense, and the stove buzzes, the door is covered. Then, in the process of burning, the access of air from the blower is gradually blocked - here you need to focus on the tone of the stove sound. If the air damper is accidentally closed, and the intensity of the flame has decreased, it must be opened again and the stove will flare up with renewed vigor.

Advantages and disadvantages of a rocket stove

Before proceeding to the description of the manufacturing process of the rocket furnace, it is desirable to summarize the information about its advantages and disadvantages.

Rocket stoves are quite popular due to their positive qualities , which include:

• Simplicity of design and a small amount of materials.
• Even a novice master can make any of the furnace designs, if desired.
• The construction of a rocket furnace does not require the purchase of expensive building materials.
• Undemanding to the forced draft of the chimney, self-regulation of the furnace.
• High efficiency of the rocket furnace with a pyrolysis gas afterburning system.
• Possibility of adding fuel during furnace firing.

Despite the large number of advantages of this design, its work has a number of shortcomings :

• When using the simplest design of a rocket stove, only dry branches and torches can be used, since excess moisture can give back thrust. In a more complex appliance system, the use of wet wood is also not recommended, because it will not give the right temperature for pyrolysis to occur.
• The rocket stove cannot be left unattended during combustion, as this is very unsafe.
• This type of device is unsuitable for heating a bath, as it does not give enough heat in the infrared range, which is especially important for a steam room. A rocket stove with a stove bench can only be suitable for a rest room in a bath building.

Video: dissenting opinion on rocket stoves

Making a rocket stove with a bench

Rocket stoves can be of different sizes, and a variety of materials are used for their manufacture - these are metal pipes, barrels and gas cylinders, bricks and clay. A combined option is also quite acceptable, consisting of pipes, stones, clay and sand. It is he who deserves special attention.

From a gas cylinder, you can make a stove that is simple in design, including using it for the option with a stove bench.

How to make a simple stove in itself is more or less clear from the above drawings and a description of its work, so it is worth considering the manufacture of a heating unit equipped with a stove bench.

Video: homemade rocket stove from a gas cylinder

You may be interested in information on how to do with step by step instructions

To make it completely clear what and where is located in the design of the rocket furnace, this scheme will be used to describe the work.

So, the considered furnace-rocket consists of the following elements:

• 1a- a blower with an air supply regulator, with which the stove is adjusted to the desired mode;
• 1b- a fuel chamber (bunker) with a blind cover;
• 1v- a channel for supplying secondary air, which ensures complete combustion of pyrolysis gases emitted by wood;
• 1g– flame tube 150÷200 mm long;
• 1d- primary chimney (riser), with a diameter of 70 ÷ 100 mm.

The flame tube must not be made too long or too short. If this element is too long, then the secondary air in it will quickly cool down and the process of afterburning pyrolysis gases will not reach the end.

The entire design of the flame tube and riser must be thermally insulated as efficiently as possible. The task of this node is to ensure the complete combustion of pyrolysis gases and the supply of hot masses from the riser to other channels, which will already transfer heat to the room and to the bench.

Here it should be noted that in order to obtain the optimal efficiency from the furnace, the diameter R the aizer should be made with a size of 70 mm, and if the goal is to achieve the maximum power of the furnace, then it should be made with a diameter of 100 mm. In this case, the length of the flame tube should be 150÷200 mm. Further, when describing the installation of the furnace, the dimensions will be given for both cases.

It is impossible to immediately let the heated air from the riser into the heat storage, since its temperature reaches 900÷1000 degrees. High-quality heat-resistant heat-accumulating materials have a rather high price, therefore, most often, adobe (clay mixed with chopped straw) is used for these purposes. This material has a high heat capacity potential, but is not heat-resistant, so the design of the secondary furnace (cylinder body) begins with an air temperature converter, which must be heated to only 300 degrees. Part of the generated heat is immediately given into the room and replenishes the current heat loss.

The described functions are performed by the furnace body, made from a standard 50 l gas cylinder.

• 2a- cover of the furnace body. Under it, heated air enters from the riser;
• 2b- a cooking surface, which is heated from the inside by heated gases leaving the riser;
• 2c– metal insulation of the riser (shell);
• 2g– heat exchange channels. Heated gas enters them, dispersing under the ceiling of the case;
• 2d– the lower metal part of the case;
• 2nd– exit from the housing to the cleaning chamber.

The main task in the arrangement of these parts of the furnace is to ensure complete tightness of the chimney line.

In the housing (drum), at a height of ⅓ from its "ceiling", the gases cool down and already have a normal temperature for their entry into the accumulator. Approximately from this height and to the floor of the room, the oven thermally insulated several layers of different compositions - this process is called lining.

• 3a- the second cleaning chamber, through which the heat exchanger ("hog"), located under the bench, is cleaned from carbon deposits;
• 3b– sealed door of the second cleaning chamber;
• 4 - "hog", a long horizontal section of the chimney, located under the stove bench.

After passing through the pipes of the "hog" and almost completely giving off heat to the adobe stove, the gases escape through the main chimney channel into the atmosphere.

Having dealt with the device of the rocket furnace in detail, you can proceed to its construction.

Building a rocket oven with a stove bench - step by step

Primarily, you need to prepare lining compositions. Their components will cost quite inexpensively, since they can often be found completely free of charge, literally under your feet:

• 5a- adobe. As mentioned above, this is clay mixed with chopped straw and mixed with water to the density of the masonry mortar. Clay for making adobe is suitable for any, since it will not be influenced by external atmospheric influences;
• 5 B- kiln clay mixed with crushed stone. This will be the main heat insulator. The mortar should have the consistency of a mixture for laying bricks;
• 5v- heat-resistant lining, made of kiln clay and fireclay sand in proportions of 1: 1 and having the consistency of plasticine;
• 5g- ordinary sifted sand;
• 5d - medium-fat clay for kiln masonry.

Step-by-step work on the design is carried out in the following sequence:

Bed for a couch

Having prepared all the necessary compositions, a bed is made - a wooden durable shield of the desired configuration. Its frame is made of timber with a section of 100 × 100 mm. Frame - with cells measuring 600 × 900 mm under the stove and 600 × 1200 mm under the bench. If a curvilinear shape of the couch is planned, then it is brought to the desired configuration with the help of boards and scraps of timber.

Bed - frame base for further construction of the furnace structure

The frame is sheathed with a grooved board 40 mm thick - it is fixed across the long sides of the frame. Later, after the installation of the furnace is completed, the side facade of the bed will be sheathed with drywall. All parts of the wooden structure of the bed must be impregnated with a biocide, and then stained twice with a water-based emulsion.

Further, on the floor, in the place of the room where the stove will be installed, mineral cardboard (cardboard made of basalt fibers) 4 mm thick is laid, the size and shape are fully consistent with the parameters of the bed. Directly under the stove, a sheet of roofing iron is fixed on top of the cardboard, which will come out from under the stove in front of the firebox by 200 ÷ 300 mm.

Then, the bed is transferred and firmly installed on the selected and made location oven, so that the frame stands stably, without play. At the end of the future couch, at a height of 120 ÷ 140 mm above the level of the bed, a hole for the chimney is arranged in the wall.

Formwork and pouring the first level of adobe mixture

A solid formwork is installed along the entire contour of the bed, having a height (A -40 ÷ 50 mm) and a smooth upper edge.

An adobe mixture (5a) is poured into the formwork and its surface is leveled using a rule. Formwork sides serve as beacons for leveling.

Production of the furnace body

• While the adobe filling will dry, and this process will take 2-3 weeks, you can start making the furnace body from a cylinder. It should be noted that a rocket stove is made from a barrel in the same way.

Cutting a gas cylinder and making a cap with a "skirt"

• The first step is to cut off the top from an empty cylinder to obtain a hole with a diameter of 200 ÷ 220 mm. Further, this hole is closed with a 4 mm thick steel round timber prepared in advance - this surface will play the role of a hob. After that, another cut is made below the hob by 50 ÷ 60 mm in order to get a lid.
• On the outer perimeter of the resulting cover is welded, so-called"skirt" made of thin sheet steel. The width of the skirt should be 50 ÷ 60 mm, the seam of this strip is welded. If there is no experience in welding work, then it is better to entrust this process to a professional.
• After that, along the entire circumference of the skirt, stepping back from the lower edge of 20 ÷ 25 mm, holes are evenly drilled into which the bolts will be screwed.
• Further, the lower empty part of the cylinder is cut off at a height of approximately 70 mm from the bottom. Then, a hole is cut in the bottom of the cylinder for the riser to enter the body.
• After that, it is necessary to fix a well-woven asbestos cord on the inner edge of the lid with Moment glue, and then immediately put it on the cylinder body and press it down with a load of 2.5 ÷ 3 kg from above. The cord will serve as a sealing gasket. Further, through the holes in the metal “skirt”, through holes are drilled in the cylinder body, in which the threads for the bolts are cut.
• After that, you need to measure the depth of the hull, since it is necessary to determine the height of the riser.
• Then the cap is removed from the cylinder to protect the gasket from being completely impregnated with glue, otherwise the asbestos will lose its elasticity.

Production of the furnace part of the furnace

The next step is to make elements from a square pipe (or channel) with a section of 150 × 150 mm: 1a - blower, 1b - combustion chamber; 1d - flame channel.

The riser (1d) is made from a round pipe with a diameter of 70 ÷ 100 mm.

The angle of insertion of the combustion chamber (bunker) into the blower and flame tube can vary within 45 ÷ 60 degrees from the horizontal. Its upper edge is placed flush with the protruding blower element, as shown in the diagram.

In the lower part of the blower and flame tube, it is necessary to separate the secondary air channel (1c). It is separated by a metal plate 3 ÷ 4 mm thick. Its rear edge should end exactly at the level of the front wall of the riser, and the front edge should go ahead of the blower by 25÷30 mm. The plate is pinpointed in four places by welding inside the pipe.

Then, at the end of the flame tube, a hole is cut from above, into which the riser is welded at a right angle, and the end of this channel is closed with a metal square, also fixed by welding.

Must be installed on the blower door - latch to help regulate the air supply. The cover for the combustion chamber is made of galvanized metal. The hopper does not require hermetic closure - the main thing is that the lid fits snugly against the inlet.

After that, the finished structure is coated with a solution of 5v. A solid lining is made only at the bottom, and the sides and top of the blower are left free from the lining. In order for the coating mixture to dry out faster, the structure is put on the pole with a blower chamber. It is necessary to ensure that the mixture from the surfaces does not slip and does not opal, since the lining plays a big role in retaining heat. If this happens, then the coating must be done again, using a fatter clay.

Rocket Furnace Insulation

After the adobe layer has dried, a formwork is installed to equip the heat-resistant thermal insulation for the furnace. It is done only under the location of the furnace. The height of the formwork will be 100÷110 mm together with the adobe layer.

The installed formwork is filled with composition 5b and leveled along the beacons, which will serve as the sides of the formwork. On the main diagram, this layer is marked with the letter B.

Production of the bottom part of the drum and shell

The shell is made from a round pipe with a diameter of 150 ÷ ​​200 mm or it is rolled from a steel sheet.

The bottom round timber, which will be laid inside the drum, is cut out of sheet metal with a thickness of 1.5 ÷ 2 mm, and a round hole is cut out in the middle of it. The diameter of the circumference of this element should be 4 mm less than the inner size of the cylinder, and the diameter of the middle cutout for the shell should be 3 mm larger than its outer diameter.

Installation of the furnace structure

After the thermal insulation layer has dried in the formwork, a furnace structure is mounted on it. It is installed by controlling the level vertically and horizontally, and then fixed on the heat-insulating layer with the help of pegs. Then, around the furnace, formwork is installed with a height of 350 ÷ 370 mm from the floor. Here it should be taken into account that the cleaning chamber (3a) and its door (3b) must be installed next to the solidified mixture (5b) with which the formwork will be filled. The connection (2e) of the cleaning chamber with the heat exchange channel (2g) will pass over the lining composition poured into the formwork. The mixture is also aligned to the ideal, level with formwork, with regulations.

cleaning chamber

While the mixture is drying in the formwork, you can start manufacturing a cleaning chamber with a door and a transition to a heat exchanger. It is made of galvanized steel, 1.5 ÷ 2 mm thick, and its front part is made of metal 4 ÷ 6 mm. A hole with a diameter of 150 ÷ ​​180 mm is cut out in the side part of the cleaning chamber to install the end of the chimney pipe, which will pass under the lounger.

The door of the cleaning chamber is made with a size of 160 × 160 mm, also from steel of 4 ÷ 6 mm. Before its installation, a sealing gasket made of mineral cardboard is installed along the perimeter of the inner surface. The door itself is screwed to the chamber box with fixing bolts, for which threads are cut in the drilled holes.

This diagram shows the dimensions of all elements and the place of installation and connection of the chamber with the drum (cylinder). Further, after fitting the elements, a 70 mm window is cut out in the lower part of the furnace drum, into which the connecting channel (2e) will be mounted by welding.

Corrugated pipes under the bench can be located arbitrarily, depending on the configuration of the lounger, it is only important to adhere to the dimensions indicated on the drawing for the manufacture of the cleaning chamber, indicated under the letters A, B and C. How to properly connect the "hog" pipe will be discussed below.

Drum mounting

When the solution in the formwork dries, it is removed. On the riser, on top of the frozen thermal insulation, they put on a combustion system drum made of a gas cylinder. The drum is currently mounted without a cover - its installation is shown in the diagram.

Solution 5b is laid out on the bottom part of the installed drum, and with the help of a spatula, a surface inclined by 6-8 degrees is formed from it, towards the outlet window of the cleaning chamber. Then, on the riser, a round timber from a metal sheet is put on and lowered to the bottom of the drum and pressed against the laid mortar. From the middle hole around the riser, the solution is selected, otherwise it will not be possible to install the shell pipe. After that, the pipe itself is put on the freed space on the riser and slightly screwed into the solution. All gaps formed along the outer and inner contours are smeared with clay (5d).

Fuel structure lining from the inside

After installing the shell and hearth, it is not necessary to wait for the thermal insulation solution to dry, you can immediately proceed to the riser lining. The composition (5g) is poured into the shell, around the riser, in 6÷7 layers. Each of the layers must be compacted as much as possible, while wetting the dry mixture with water from a spray bottle. From above, this space filled with sand is closed with a clay layer (cork) 50 ÷ 60 mm thick, using a solution of 5d.

Cleaning chamber installation

After mounting the drum, you need to install a cleaning chamber. Installing the box is not difficult - for this, a layer of solution 5d is applied to the transition channel and the hole in the drum, as well as to the side and bottom of the box, which has a thickness of 3 ÷ 4 mm. The box is put in place, and the transition channel window (2e) is inserted into the prepared opening of the drum and is well pressed and pressed down. The solution that comes out on the sides is immediately smeared. The entrance of the cleaning chamber to the drum must be well sealed, therefore, if there are gaps left, they must be sealed well.

Laying the thermal insulation layer

Formwork for level G

Further, a formwork is installed along the outer contour of the bed, just as in the manufacture of level A. The height of this level G must be displayed, focusing on the hole for connecting the “hog”. Above the upper edge of the hole, the level should be raised by about 80÷100 mm.

Formwork filling

The next step is filling the formwork with adobe mortar (5a) to the bottom edge of the hole prepared for the installation of the "hog" in the cleaning chamber one side, and at the end of the bed - to the lower edge of the outlet for the chimney.

The mixture is laid out and leveled by hand, while making sure that the mass is as close as possible to the previous layer. Thus, from the cleaning chamber to the chimney outlet rise is formed for pipes "hog", the height difference of which should be 15 ÷ 30 mm. This design is necessary so that the couch warms up evenly.

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Installation of a corrugated pipe

The next step is to stretch the corrugated pipe over the entire length of the bed. One end is connected to the cleaning chamber, inserted into the hole to a depth of 20÷25 mm and flaring inside the chamber with a flathead screwdriver through the cleaning door. Then the entrance of the pipe to the ash pan is coated with a solution of 5d, and the beginning of the pipe 150 ÷ ​​200 mm is coated with adobe. This will fix the rub well in the desired position and prevent it from slipping out of the hole during further work.

After that, the pipe in the formwork is laid in the form of a coil, but it must always be at a distance of about 100 mm from the edges of the formwork and the wall. During the laying process, the pipe is pressed into the adobe layer laid under it. Having laid the pipe along its entire length, its second end is fixed on a clay solution in the outlet chimney.

After that, the entire "hog" is plastered with adobe mortar, which must be well compacted, especially between the bends of the pipe, so that no voids form in it. After the adobe mass fills the space flush with the top of the corrugated pipe, a more liquid solution of adobe is poured into the formwork, and at the end the surface is smoothed out by a rule that is carried out along the walls of the formwork, which act as beacons ..

You may be interested in information about what they are on wood

Cover installation

After that, the covers of the cleaning chamber and the drum are fixed with bolts. They need to be tightened tightly so that they press the gaskets installed inside.

Furnace drum coating

Further, the oven drum is coated with adobe by ⅔ from the bottom of the body. The upper part of the drum is left free from the adobe layer. Thermal insulation is applied with a thickness of at least 100 ÷ 120 mm, and the configuration of the coating is chosen by the master himself.

Furnace finish

After two or two and a half weeks, the adobe layer should dry out and the installed formwork can be removed. Then, if necessary, the right corners of the structure are rounded. In addition, the drum is covered with heat-resistant enamel that can withstand temperatures up to 450÷750 degrees. The adobe surface of the couch is covered with acrylic varnish in two layers, each of which should dry well. The varnish will hold the surface material together, preventing it from dusting, protect the adobe from moisture and give the glazed clay the aesthetics.

If desired, a wooden flooring made of thin boards can be laid on the surface of the couch - it is quite often made removable. The side parts of the couch are sometimes trimmed with drywall or lined with stone. Decorative finishing is carried out to the taste of the owner of the house.

You may be interested in information on how to build

Carrying out a furnace test

A dry oven must be tested. To do this, it is necessary to warm up the structure by laying light fuel in the form of paper in the blower and replenishing it during the combustion process. When heat is felt on the surface of the bed, you can put the main fuel into the combustion chamber. When the stove starts to hum, the blower closes until the sound changes to a “whisper”.

In conclusion, it must be said that the rocket stove can also be made of brick or stone - it all depends on the financial capabilities and creative abilities of the master. The main thing that can attract in this design is the ability to improvise and create using different materials for construction and decoration. Therefore, those who dream of installing a stove with a heated stove bench in their home should take a closer look at this option.

Prices for ready-made rocket stoves

furnace rocket

Video: an example of building a rocket stove with a warm stove bench

Evgeny AfanasievChief Editor

Publication author 18.01.2016

You can make a rocket furnace yourself using ordinary steel The rocket stove is widely known throughout as a long-burning solid fuel heating structure. To achieve the maximum efficiency had to work hard. A liquid fuel stove is able to give all its energy, but wood is more difficult to process. To unlock the full potential of the tree, a chamber for afterburning gases was equipped in jet furnaces.

• • The principle of operation of a long-burning rocket furnace
  • Do-it-yourself rocket stove: advantages, drawings, disadvantages
  • Drawings of a jet furnace from a gas cylinder and other types
  • Do-it-yourself drawings of the Ognivo stove and other models
  • Assembling a do-it-yourself jet furnace for heating
  • Advanced Water Loop Rocket Furnace
  • Do-it-yourself rocket furnace drawings (video)
  • Examples of a rocket stove (photo ideas)

The Shirokov-Khramtsov rocket or jet furnace got its name not because of its connection with space. The point is the shape of the device and the noise that is created during operation, reminiscent of the operation of a rocket. But this sound indicates improper use of the oven.

Types of long-burning rocket furnaces:

• Portable (mobile);
• Stationary (for heating).

The most popular rocket model is the Robinson. It is often used on hikes. Thanks to a small portable apparatus, you can understand the principle of operation of jet furnaces. The shape of the oven resembles the letter "L".

If the oven is too noisy and hums during operation, then this mode is inefficient and expensive. Normally, there should be a quiet sound, a little rustling.

The jet furnace has a receiving hopper. This is the horizontal part of the pipe. A thrust arises in the channel itself, it is it that affects the intensity of combustion, which warms up the body. That is why it is advised to limit the supply of oxygen. Otherwise, the firewood will quickly burn out and all the heat will evaporate.

A long-burning rocket stove is often used to heat garages and utility rooms.

The stove is powered by jet thrust due to the natural flow of hot air. The higher the temperature of the furnace walls, the better the wood burns. This allows you to quickly heat water in a large container, which is indispensable on a road trip. If you equip the pipe with thermal insulation, then after warming up, you can burn thick logs.

Do-it-yourself rocket stove: advantages, drawings, disadvantages

If desired, the conventional design of the furnace can be improved. So the potbelly stove loses a lot of heat, but by equipping the device with a water circuit or brickwork, these problems can be solved. For all these manipulations, drawings are made.

Advantages of jet ovens:

1. Simple and cost effective design. You can use improvised materials, without significant financial costs. All work can be done by hand, special knowledge and skills are not required.
2. You can independently control combustion by choosing the desired intensity.
3. High efficiency. In general, it all depends on the quality of the installation. The main thing is to take away the maximum energy from the flue gases.

But such a simple and convenient design has significant drawbacks. So you need to select a special fuel for the potbelly stove. Wet firewood must not be used, otherwise pyrolysis will not occur. The furnace may begin to smoke profusely, and all gases will go into the house. In addition, the rocket furnace requires increased safety requirements.

The most popular portable model is the Robinson rocket stove. It was modified and a grate was added.

Homemade jet stoves are not used for heating baths. They are ineffective in infrared light, which plays an important role in the steam room. Surface structures have a small heating area, so they cannot heat the bath.

Drawings of a jet furnace from a gas cylinder and other types

Long-burning furnaces are divided into stationary and mobile. Mobile stoves are used in hiking, picnics, outdoors for heating and cooking. Stationary ones are used to heat the house, outbuildings, greenhouses, garages. In this case, 4 types of structures are distinguished.

Types of jet furnaces:

• Homemade camp stove made of metal pipes, buckets, cans;
• Reactive design from a gas cylinder;
• Brick oven with a metal container;
• Stove with bed.

Drawings of a jet furnace from a gas cylinder can be downloaded on the Internet or made independently by hand

The portable structure is equipped with pipe sections. The only difference concerns the installed partition for the ash pan. For the lower part, a grate can be used.

A device from a gas cylinder is more difficult to build, but significantly increases efficiency. For installation of the structure, a barrel or a gas cylinder is required. Firewood in the firebox burns out due to the influx of oxygen by loading through a special window.

The gases burn out in the pipe, which is located inside the structure, due to the supply of secondary air. The effect is enhanced by warming the inner chamber. Hot air is placed in the hood, and then into the outer chamber. The products of combustion are removed through the chimney.

To create draft, the top of the chimney is placed 4 cm above the loading window.

The combined brick and metal model is a stationary structure. Due to the high heat capacity, the wood stove accumulates and releases heat for several hours. That is why this design is used to heat residential premises.

A rocket assembly with a bed is an advanced device that is able to retain heat longer. Since part of the heat exits through the chimney, we increased its length. Due to the rapid excision of hot gases and a larger chimney, this problem was solved.

This is how massive stoves with a stove bench are obtained, which are similar to a sofa or bed. These are stationary devices made of brick or stone. Thanks to its unique design, the stove is able to retain heat all night.

Do-it-yourself drawings of the Ognivo stove and other models

It is best to make small portable structures with your own hands: the Flint and Robinson rockets. It is easy to perform the calculation, and the work will require cutting profile pipes and metal welding skills. Dimensions may differ from the drawing, it's not scary. It's important to keep the proportions.

To increase the intensity of combustion, it is advised to add improvised nozzles to the design. Secondary air for afterburning will flow there.

Stationary rocket stoves are made from a gas cylinder or a metal barrel. These elements act as a body. Inside, the stove is equipped with smaller pipes or fireclay bricks. From the cylinder, you can make both a stationary unit and a mobile one.

Scheme of a continuous combustion furnace:

• Chimney;
• Cap;
• insulation;
• loading bunker;
• Burning zone;
• Afterburning zone.

The Ognevo furnace can be bought in a specialized store at a fairly reasonable price.

It can be difficult to calculate a rocket furnace, because there is no exact methodology. You should pay attention to the checked finished drawings. It is necessary to determine the size of the heating equipment for a particular room.

Assembling a do-it-yourself jet furnace for heating

The construction of the furnace begins with preparatory work. First you need to decide on the place of construction. It is chosen based on the requirements that apply to solid fuel structures: wood or coal.

When you have decided on a place, you need to properly prepare it for construction. The wooden floor under the stove is dismantled. They dig a small pit and tamp the bottom.

In a small room, a jet furnace is placed in the corner. The loading bunker occupies one side, and the lounger the other.

The barrel or cylinder must also be prepared for installation. To do this, they cut off the lid and the tap. Then the structure is cleaned. Next, prepare the solution.

Stages of construction of a jet furnace with a bench:

1. The bottom of the dug pit is laid out with fireclay bricks. Formwork is made along the contour of the recess. Perform reinforcement.
2. Lay out the base and pour concrete. After a day, when the concrete hardens, further work begins.
3. The base of the stove is laid out from fireclay bricks. Raise the side walls, make the lower channel.
4. The combustion chamber is covered with brick. There are two holes on the sides. One is for the firebox, the second is for the vertical pipe (riser).
5. The metal case is equipped with a flange into which the horizontal channel of the stove will enter. All seams must be airtight, well sealed.
6. A side outlet is attached to the horizontal pipe, which serves as an ash pan.
7. A fire tube is made of brick. As a rule, it is square.
8. The flame tube is equipped with a casing. The gaps are filled with perlite.
9. Installation of the cap is made from the cut off part of the barrel or cylinder. It is equipped with a handle.
10. Equip the furnace body with brick or stone.
11. Equip the front of the furnace. Lay out the necessary contour.
12. A prepared barrel is placed on the base. The lower part must be sealed with clay.
13. With the help of a corrugated pipe, a channel is formed that connects the firebox with the street.
14. The pipes of the heat exchanger are connected to the lower pipe.
15. Install a chimney. All elements must be sealed using asbestos cord and refractory coating.

To properly assemble a jet furnace with your own hands, you should first watch the training video and study the recommendations of experts

Advanced Water Loop Rocket Furnace

A long-burning cauldron can be obtained by equipping a furnace with a water jacket. Water heating may not be efficient enough. The fact is that the bulk of the warm air enters the room and containers on the hobs. To create a rocket cauldron, it is necessary to give up the possibility of cooking on a stove.

Materials required for equipping a stove with a water circuit:

1. fireclay bricks and masonry mortar;
2. Steel pipe (diameter 7 cm);
3. Barrel or balloon;
4. insulation;
5. Sheet steel and a barrel of a smaller diameter than for the hull to create a water jacket;
6. Chimney (diameter 10 cm);
7. Details for the heat accumulator (tank, pipes, connecting pipe).

A characteristic feature of rocket furnaces with a water circuit is that the insulation of the vertical part ensures the combustion of pyrolysis gases. In this case, warm air is sent to the coil with a water circuit and gives off heat to the stove. Even when all the fuel has burned out, warm air will still be supplied to the heating circuit.

Do-it-yourself rocket furnace drawings (video)

Jet oven stove benches are widely known among the people. They were used even by Korea, China, England and the population of Japan. The Chinese stove differed from the rest in the ability to heat the entire floor. But the Russian counterpart is in no way inferior. Thanks to useful innovations, the stove is able to keep heat for a long time.

Examples of a rocket stove (photo ideas)