Home > Projects > Do-it-yourself bubafonya stove: diagram, drawing, calculation and construction. Do-it-yourself long-burning stove “Bubafonya” Bubafonya stove from a barrel

Do-it-yourself bubafonya stove: diagram, drawing, calculation and construction. Do-it-yourself long-burning stove “Bubafonya” Bubafonya stove from a barrel

Long-burning stoves are becoming increasingly popular. Well, who doesn’t want to spend less fuel (read: money) and time on heating? Everyone wants it. Moreover, it is not at all necessary to buy expensive boilers. There are very interesting long-burning stoves that you can easily make with your own hands. For example, very interesting and original design such a stove is Bubafonya. This fuel boiler was invented by a craftsman from Kolyma and posted on one of the forums. Since the author’s nickname was bubafonja, it became customary that the stove is called Bubafonya (sometimes Bubafoniya or Bubofonya). The first reports of this design date back to 2008. In such a very short period of time (6 years) she became very popular.

How Bubafonya works, its advantages and disadvantages

The design of this miracle stove is such that the movable piston rests on the firewood stacked at the bottom of the firebox. It divides the combustion chamber into two parts: firewood burns below it, and pyrolysis gases burn out from above. It turns out that the firewood does not burn from bottom to top, as usual, but from top to bottom. The process is much slower, and the fuel burns with virtually no residue. Oxygen for burning wood is supplied through a pipe, which serves as a rod for the piston. In the upper part of the furnace, where the pyrolysis gases burn, oxygen enters through the holes in the lid (where the pipe from the piston is inserted, and where the lid is combined with the body), so there is no need to worry about tightness. This is even harmful - the stove “suffocates” if there is a lack of oxygen. Due to this separation of the chambers, the fuel burns out completely. The combustion intensity is regulated through a pipe to which the piston ring is welded. For convenience, people weld a small pin to the pipe, to which a metal disk is movably attached, the diameter of which is slightly larger than this pipe. Some simply block or restrict the flow of air to any object, adjusting this gap.

The burning time of one bookmark depends to a large extent on the volume of the firebox: the larger the firebox, the more firewood, the longer the fuel burns. On average, one load of firewood in Bubafonya from a gas cylinder burns for 4-6 hours (depending on the firewood and other “additional” fuel). Those who made Bubafonya from a 200 liter barrel say that one filling heats them up to 20-24 hours. It’s not for nothing that they say that Bubafonya is a long-burning stove. Indeed, it burns for a long time.

Despite the obvious advantages, this stove also has disadvantages: the first is a small “radius of action” with high heat transfer. It’s warm, even hot, near the stove. If you move a little further, it’s cold. But this problem can be solved. To improve the situation, they do it in two ways: they arrange forced convection (air change) using a fan or make a water jacket, and run the heated water through pipes to heat the room.

If everything is simple with the fan, then the water jacket can be made in two ways: around the body or removing heat from the chimney pipe. A shirt on the chimney is easier to implement. This option has one more advantage: the heat from the stove body is then used for heating, as well as the heat that previously went outside through the chimney. Now it also heats your room. In addition, when installing a water jacket on the pipe, the smoke at the outlet will no longer be so hot and you won’t have to worry so much about insulating the wall around the pipe. How .

The Bubafonya stove can be used to organize water heating by making a water jacket on the body or pipe

Another important drawback is that it is not the most attractive appearance. If Bubafonya is used in technical room- in a garage, greenhouse, or at the dacha, then there is nothing particularly to worry about. It is what it is. Well, if you want to heat your house with it, you will have to hide it somewhere in the boiler room, basement, or outbuilding. You can still refine it. For example, cover it with brick. By this way, you will greatly increase the comfort of being near the stove: the brick will extinguish most of hard radiation, softens it, and becomes a kind of heat accumulator: the brick will heat up, and then, when the stove goes out, it will gradually cool down and release the accumulated heat.

It is not recommended to paint Bubafonya: there is no point - the paint will burn, and even if it burns it can poison it. The paint will only withstand one case, if it is heat-resistant, but it must be applied according to all the rules, and this is not at all easy and expensive.

The disadvantage of “Bubafonya” is its unprepossessing appearance, but it heats very well and burns for a really long time

Do not forget that Bubafonya is an iron stove. Simply placing it on a wooden floor will not work - a fire may occur. And very quickly: the pyrolysis temperature is very high (350 o C and above), therefore, the furnace body has a high temperature. So it can seriously burn, and it will also burn the wood of an unprotected floor or nearby walls. So we pay close attention to fire safety and prepare a place for the stove: we use asbestos-cement slabs, metal sheets, bricks, heat insulating materials(mineral wool or cardboard and other heat-resistant materials).

The operation of the stove is also somewhat problematic, but this is the opposite of the simplicity of the design. Selecting ash and loading fuel is inconvenient. Actually, there are two options here: accept this as a fact or make changes to the design. But how they (the changes) will affect the efficiency of the furnace is difficult to say. It must be said that very little ash remains from firewood and sawdust, so it does not need to be cleaned often.

There is one simple option for modifying the Bubafonya stove, which allows you to easily remove ash: weld a special ash pan. It consists of the same pancake as the piston, but without a hole and with edges curved upward. We weld a thick metal rod to the middle of the ash pan. Then, when assembling the stove, we put an ash pan on the bottom, put fuel on it, and light it. Then we put a piston on the ash pan rod, and finally a lid. With this design, the ash is collected in a tray, which is easily pulled out of the cooled and disassembled boiler using a rod.

This is what “Bubafonya” looks like from the inside when the fuel in it is smoldering

What is needed for production and how to make it

This stove has two big advantages: it is easy to make yourself and it burns for a very long time. There is no point in indicating dimensions: everyone uses what is at hand without reference to any standards. Structurally, the furnace consists of:

Cases.
Lids.
Piston.
Chimney pipes.

For manufacturing of body and cover Bubafoni may be suitable:

Empty gas cylinder;
Thick-walled metal barrel(with or without top);
Pipe section of medium or large diameter(the wall must be thick);
Sheet metal (you will need to bend it and weld a pipe from it).

The original stove was round, but today there are also square ones. Craftsmen use the operating principle and change the design to suit their needs.

The easiest way to make a Bubafonya stove is from a gas (propane, oxygen or any other) cylinder. You just need to cut off the top of the cylinder and weld stops or clamps to the top (lid) that will hold the lid on the body.

Cut off the top from the old cylinder and the body for the Bubafoni is ready, all that remains is to modify the lid a little: weld the stops

It is easy to make a body for the Bubafonya stove from a barrel. Especially if the barrel has a riveted/rolled/welded lid. You need to cut off the top part ( more convenient with an angle grinder) with a small part of the body (10-15 cm, but it can be more or less - depends on the size of the barrel). The body itself is ready. But to make it more convenient to attach the lid to it, and the edge is not sharp, use a hammer or sledgehammer to bend the edge inward. On the sawn-off part, which will be the lid, fold the edge too, but outward. Now the lid fits tightly onto the body.

Bubafonya oven! can be made from a barrel

If the barrel is without a lid, it will need to be welded from a metal pancake cut to the diameter of the barrel and a strip of metal. There is no need to worry about the lid fitting too tightly to the body. The slots are necessary to supply oxygen to the upper combustion chamber. But you can weld the handles - it will be more convenient to remove/put it on.

If you make the body from a piece of pipe with thick walls, you will need to weld the bottom well. Build the lid in the same way as described above. If there is only sheet metal, it will need to be bent. It’s easier to do this on a sheet bending machine, but if there is no such device, you will have to use improvised means. For example, wrap around a pipe suitable diameter, wood, etc. Having achieved the desired shape, weld a cylinder from the sheet, then weld the bottom and make a lid.

a metal pancake, the diameter of which is slightly smaller than the diameter of the body (precision is not needed here, the piston should move easily, and pyrolysis gases will escape through the gap between the pancake and the wall into the upper chamber);
a pipe through which air is supplied to the lower chamber;
several pieces of corner or metal strips that are welded from below to the pancake.

Cut a hole in the middle of the pancake equal to the diameter of the pipe. On one side of the pancake we weld several strips of metal or corner, which will prevent the piston from resting tightly on the wood and will ensure the delivery of air for burning the wood. Metal strips should be positioned from the edge internal hole to the outside. You can directly, you can bend it with a screw. They serve as guides for air supply. Sometimes, in order for the air to better disperse to the sides and not remain in the middle of the firebox, another pancake of a smaller diameter with a small hole in the middle is welded onto these guides.

Piston for "bubafoni"

The length of the air supply pipe is 6-10 cm greater than the height of the body. We insert this pipe into the previously cut hole and weld it. You can make additional stiffeners, since without them, after a while the pancake will “lead” from high temperatures.

The Bubafonia oven is almost ready. Not much left. In the center of the cover you need to cut a hole through which the piston pipe will pass (slightly larger than the diameter of this pipe). There is also no need to worry about tightness: air will flow through the gaps for combustion of pyrolysis gases.

We weld the chimney pipe. In the housing below the mark where the lid ends, we cut a hole for the smoke exhaust pipe. To ensure normal traction, it is recommended to use a diameter of at least 100 mm - this is if the body is made of gas cylinders; for structures with a larger diameter, it is recommended to use 150 mm. The length of the horizontal section of the chimney is about 40 cm, then the chimney rises upward. Its total height is at least 2-3 meters. Better - more. Most stove owners make 4-5 meter chimneys.

It is recommended to make the chimney itself prefabricated. And start the assembly not from the stove, as usual, but from the roof - this will make it easier to disassemble it for cleaning. You can make a glass with an inspection so that you can remove the soot without dismantling the chimney.

How and with what to drown Bubafonya

The beauty of this design is that it is easy to adapt to any fuel. In this “pristine” form, it is more suitable for firewood. But firewood can also be sprinkled with some kind of waste: wood chips, sawdust, sunflower or buckwheat husks, etc. The more fuel is compacted in the boiler, the longer the stove will burn, but at the same time, the level of flammable materials must be lower than the exit of the chimney opening.

If you are going to heat Bubafonya exclusively with sawdust, the thickness of the walls of the stove should be larger (at least 10 mm), as well as the size of the boiler - the density of sawdust is low, just like a rammer. There is no need to introduce any other design features. Unless you come up with a device for supplying fuel inside the firebox. Sawdust is not firewood, it can crumble.

To ensure that sawdust burns normally, before filling it into Bubafonya, insert a pipe or a shovel holder, pour sawdust around the pipe, and compact it. When all the fuel is in, remove the pipe. Now you can fire up and install the piston.

You can make the Bubafonya furnace work during mining. In order not to redo the structure, you place several broken refractory bricks and several whole standing ones on the bottom (the piston rests on them), and a “fuel line” is passed through the air supply pipe. You can use a smaller diameter pipe for this purpose. Between broken bricks light the fire, place the piston and lid on top.

There are many options for the Bubafonya stove with various modifications and improvements. Some of them work better, others worse. Everyone adapts a great idea to their needs and to the type of fuel that is more accessible/convenient for them. About one of the options. The only thing Bubafonya is not very friendly with is coal. It has a high ash content, and some brands are sintered. The slag has nowhere to go and often “smothers” the flame. The situation is better if you mix the same coal with firewood, sawdust, etc., but the problem of ash content or caking does not go away. A good option is to heat with briquettes. In this case, you can use coal briquettes and any others: their ash content is much lower, and the stove burns for an unrealistically long time. Briquettes themselves burn for a long time, and long-burning stoves in general take a very long time. Read more about and about. So we can say that the Bubafonya stove works with any type of fuel.

During the cold period of the heating season, the issue of heating rooms becomes more relevant than ever. And if in city apartments, as a rule, housing and communal services are responsible for this, then residents of the private sector have to deal with all the problems that arise on their own. For a conventional wood-burning stove, it is necessary to purchase a significant amount of logs, and this often takes a serious toll on consumers’ pockets. In addition, some need to heat not only residential but also auxiliary premises, such as garages or greenhouses. Therefore, there is a natural desire to find a method for the most economical and efficient heating.

Do-it-yourself bubafonya stove: diagram and drawing

First, we need to understand how wood burning actually occurs. For wood to ignite, it must first be heated to a temperature of about one and a half hundred degrees from external source heat. As a rule, this task is performed by setting paper or wood chips on fire with a match. The wood begins to slowly char and, when it reaches about 250 degrees, it decomposes into simple chemical components. The white smoke we see when lighting a fire is the gases and water vapor released by heated wood. And so, having crossed the level of three hundred degrees, the gaseous substances released from the tree ignite, further accelerating the thermochemical reaction.

The decomposition of organic fuel, such as wood, into simple elements is called pyrolysis. And everything would be fine, but ordinary wood combustion does not fully utilize the entire potential contained in the energy carrier. A lot of waste remains, which ultimately does not contribute to savings.

Pyrolysis furnaces, one of the options of which we will consider in this article, use fuel much more efficiently. The main secret is that the combustion of gases released when wood is heated occurs separately from the energy carrier itself. At the same time, the primary fuel smolders slowly, which allows for much longer operating time on one stack of logs. In “bubafonya” type stoves and other pyrolysis heating devices, everything burns out almost 100%, leaving behind only a small amount of ash.

How combustion occurs

The history of the creation of the Bubafonya pyrolysis furnace

“Bubafonya” was first assembled by a folk craftsman named Afanasy Bubyakin, who lives in Kolyma. In fact, it was named in his honor. The master took the Stropuva pyrolysis boiler, made in Lithuania, as the basis for his product. Afanasy simplified the design as much as possible so that it could easily be repeated independently. That is why the homemade pyrolysis oven “Bubafonya” is famous for its fairly high popularity.

It should be noted right away that since a homemade heating device is made from readily available materials, it rarely has an attractive and aesthetic appearance. The main advantage of “bubafoni” is its simplicity, reliability and efficiency.

Below you can see an example of a homemade stove designed by Afanasy Bubyakin, made from an old gas cylinder.

Internal structure of the long-burning stove "Bubafonya"

The main element in the design of the “bubafoni” is its body. As a rule, it has cylindrical shape: a cylinder, a large fire extinguisher, a barrel or a thick pipe with a welded bottom.
Chimney for removing waste combustion products. It is made, in most cases, from a metal pipe 11-25 centimeters in diameter, welded to the top of the body.
Feeder piston. It is a metal circle with ribs welded on the bottom, in the center of which an air duct pipe is fixed. The ribs allow you to create an additional air gap between the piston and the logs, which has a positive effect on the smoldering process and the activity of the release of pyrolysis gases.
A control valve that allows you to control the supply of oxidizer inside the furnace.
Cover with hole for air duct. Together with the piston, it forms a secondary combustion chamber, in which the pyrolysis gases are ignited.

Advantages and disadvantages of a pyrolysis oven

First of all, it should be noted positive qualities of this heating device:

"Bubafonya" has a very simple design. Owning welding machine and basic skills in working with metal, anyone can easily and simply make a stove with their own hands.
The Bubafonya pyrolysis stove is not at all picky in terms of choosing a solid fuel energy carrier. It will burn properly on wood, coal, sawdust, wood chips and other waste from wood production. In addition, it can be loaded with pellets - inexpensive and environmentally friendly granular fuel.
Opening hours. After one load of firewood, a pyrolysis oven can operate continuously and heat the air in the room for up to 24 hours. This indicator, however, can vary significantly, depending on the volume of the chamber, the oxidizer supply rate and other parameters.

But you have to pay for everything, and that's why simplicity internal device Bubafonya stoves lead to some disadvantages:

"Bubafonya" does not have high efficiency indicators. This is due to uneven heating of the cylinder body (barrel) and lower heat transfer. Pyrolysis furnaces of more complex and advanced designs, in turn, can boast excellent efficiency indicators, almost reaching a value of 90%.
“Bubafonya” is quite inconvenient to clean from combustion residues: the ash and ash have to be removed through the top. However, this homemade heater can be improved by welding a door at the bottom, which makes it easy to rake out all excess from the bottom of the oven.
Aesthetic unattractiveness. The design is quite rough in appearance and is unlikely to become a decoration interior design the room in which it will be installed.

Making a stove yourself

The entire process of creating a homemade pyrolysis boiler “Bubafonya” can be divided into five main stages:

Preparing the room, materials and tools for work
Installation and assembly of the structure
Chimney installation
Laying the foundation for a pyrolysis furnace

Let's look at each of them in more detail.

Drawing of the Bubafonya pyrolysis furnace. Calculation of basic proportions.

The fundamental proportion in the process of constructing a homemade pyrolysis furnace from a gas cylinder is the mathematical ratio of the internal diameter of the housing to its height. In the drawing, the diameter is indicated by the letter D, and the height by H. The ratio of H to D should be in the range from three to five to one. The diameter itself under optimal conditions will be about 30-80 centimeters. You should not choose a housing for a stove smaller than 30 centimeters, since the oxidizer will pass through the combustion chamber too quickly without fully reacting with the fuel. This will significantly reduce the efficiency of the device. A diameter of more than 80 centimeters is undesirable for another reason: in such a boiler, the wood at the edge burns very slowly, and in the center - faster. When the fuel burns out, a hole will form into which the piston will fall, which will lead to the extinction of the “bubafoni”.

Wall thicknessΔ is the second most important calculated value. Perfect for optimal heat transfer steel body at 4-5 mm. Smaller wall thickness will significantly reduce the service life of the heater and its operating time on one refill.

Dimensions of the piston pressing plate:

Gap With between the piston and the inner surface of the housing is optimally calculated to be 0.05*D. Accordingly, the diameter of the pancake itself will be calculated using the formula d =D-2*H

The height of the pressing ribs made of metal profiles is considered more difficult. Here the relationship between the parameter values is nonlinear. Empirically, for furnace body diameters from 60 to 80 centimeters, we take this number equal to 0.1*D. For a smaller “bubafoni” we use the proportional equation, taking into account that when D 0 = 30 cm h 0 = 4 cm.

Example of calculation by proportion. The inner diameter of the cylinder is 40 cm. We calculate the required height of the channels as follows: h=D*h 0 /D 0 =4*40/30=5.3 cm

Pancake thicknessσ. This parameter is inversely proportional to the internal diameter of the “bubafoni” D. It is necessary that the piston presses on the fuel layer with optimal force. If the pressure is low, the furnace's blowback coefficient will decrease and there will be a risk of the boiler catching fire with subsequent smoke escaping through the air duct. A piston that is too heavy, in turn, will not leave enough air space for the firewood to smolder and the “bubafonya” will go out.

This value can be found using the table below. There are no special requirements for compliance with this parameter; it is enough to adhere to it at least approximately.

D	σ
30 cm	from 6 to 10 mm
40 cm	from 6 to 8 mm
60 cm	from 4 to 6 mm
80 cm	from 2.5 to 4 mm

Calculation of the minimum required chimney area. The smallest permissible value of the pipe area S is calculated based on the maximum energy release of the fuel per hour. S(cm 2)=1.75*E(kW/hour). In this case, E=m*q where m is the mass of the loaded fuel, which can be found by multiplying the maximum volume of the load V=H f *(π*D 2 /4) by its density (we find out from the table below). Coefficient q, in turn, is the specific combustion energy of a unit volume of fuel per hour (we also take it from the reference table).

Calculation of air intake diameter

Preparing the room, materials and tools for work

Since assembling the “bubafoni” requires the use of a welding machine, not every room is suitable for our work. Definitely needed high-quality ventilation, uninterrupted supply of electricity and reliable wiring (welding operation can cause overload in the circuit). In addition, installation may take more than one day, so the room must be protected from precipitation and be sufficiently spacious. It is also important good sound insulation workplace, since the noise from the grinder, welding and other tools is unlikely to please your neighbors.

By selecting suitable place For installation, we begin to prepare materials.

The basis for the pyrolysis furnace will be an old gas cylinder. Instead, you can also use a large (about 200 liters) steel or cast iron barrel with strong walls without traces of corrosion, a large used fire extinguisher, or even a metal pipe with a welded bottom made of a steel circle.
Next we will need blanks for the supporting “legs”. In principle, you can try to do without them, but a “bubafonya” on legs will be much more stable, it is more difficult to accidentally turn it over with an awkward movement. Supports can be made from metal profiles, reinforcement and even sections of steel tubes.

Various options homemade stove legs

We can also create “handles” for more convenient carrying of a homemade stove from scraps of fittings. Also, they will not be superfluous on the lid of the “bubafoni”: this will greatly simplify the process of loading firewood and cleaning the boiler from ash.

Auxiliary materials for creating “bubafoni” will be:

Sheet steel for making a piston;
Two metal pipes for the chimney and air duct. Optimal diameter The air supply pipe is about 85-100 mm, and its length should be approximately 150 mm greater than the height of the cylinder. The chimney will require a wider pipe, with a diameter of about 150 mm. As for its length, it must be equal to at least the cross-section of the cylinder;
Metal profile (channel);
Crushed stone, concrete and refractory bricks for making the foundation;

The list of necessary tools will be small. We will use:

Hammer;
Vise;
Shovel;
Mastercom;
Portable electric welding machine with a set of electrodes;
Grinder for cutting parts;
Tape measure, pencil, plumb line and level;

Installation and assembly of the structure. Installation of the chimney.

First of all, we make a neat cut in the upper part of the balloon. The resulting cap will serve us later as a lid for the furnace.

We attach homemade legs to the bottom of the cylinder using electric welding. The correctness of their installation can be checked using a level or plumb line.
The production of the bubafoni piston occurs in three stages:

First we cut a circle out of steel. Its transverse dimensions should be approximately 3.5-4.5 cm smaller than the internal diameter of the gas cylinder to ensure free exit of the resulting pyrolysis gases into the secondary chamber. We make another hole in the central part of the circle so that the end of the air duct can be tightly inserted.

We weld the circle and the metal pipe together.

We fix channel cuttings to the base of the piston blank by welding.

The finished product will look something like this:

We construct the furnace cover. In the center of the cut off upper part of the old gas cylinder we make markings for the hole. This must be done in such a way that the air duct pipe with the attached supply piston can move freely in it. Using the markings, we make the necessary cutout. On the sides of the improvised lid we weld handles from pieces of reinforcement bent with a vice and a hammer.

We install a chimney in the upper part of the improvised pyrolysis oven. Using a grinder, we cut out a neat hole according to the dimensions of the pipe blank and fasten it together by welding.

Video: How to cut a straight hole for a chimney using a grinder.

To ensure better draft, the chimney should consist of two “elbows” connected at right angles. To do this, at the ends horizontal pipe, coming out of the cylinder and another segment of the same diameter, we use a grinder to make even cuts at an angle of 45 degrees and weld the pipes to each other.

In addition, it is highly desirable to provide protection for the chimney in the form of a special reflective cap. This will prevent moisture and precipitation from penetrating inside the furnace with subsequent extinguishing.

At this point, the main part of the installation work can be considered complete. The oven is now completely ready for use. We can only, if desired, equip a special foundation for it and begin direct operation.

Laying the foundation for a pyrolysis furnace

Work on arranging the foundation for “bubafoni” will take place in three stages:

First we need to dig a square hole measuring approximately one and a half by one and a half meters. The optimal depth for the foundation will be approximately 20-30 centimeters.

We pour crushed stone inside and pour it on top concrete mortar. Level the surface using a trowel. After drying, we check the quality of the resulting plane with a level and further correct it, if necessary.

When the concrete is completely dry, we lay several rows of refractory bricks on top of the base. As a rule, two or three brick layers will be enough.

Ignition of the Bubafonya stove

We pull out the feed piston with the welded air duct from the inside, having first removed the cap from the cylinder.

We put wooden logs inside. They must be placed horizontally close to each other. Vertical placement of firewood can have quite unpleasant consequences if an unburnt log standing on its edge interferes with the movement of the piston. This will lead to a full-fledged fire breaking out in the primary chamber instead of smoldering. As a result, the correct operating mode of the stove will be disrupted, the wood will burn faster and, in addition to everything, it may begin to smoke through the air duct. Logs cannot be placed above the location of the chimney.

Sprinkle chips with sawdust or small branches on top of the wood pile. Soak a piece in kindling liquid (kerosene is also great) old fabric and place it on a layer of wood chips. An alternative to a rag is paper.

We press the filling with the piston and put the oven lid back on.

We set fire to the wood by throwing a piece of lit rags or paper inside through the air duct. A match for lighting a “bubafoni” is not suitable, since it manages to go out before it falls down.

After 15-25 minutes, after the filling has flared up well, it is necessary to close the valve on the air duct. This will limit the air supply to the primary combustion chamber and will cause the logs to begin to smolder, releasing pyrolysis gases. Thus, the “bubafonya” will switch to its main operating mode.

Video instructions. Ignition of the Bubafonya stove

The main problem affecting the efficiency indicators of the Bubafoni is the uneven heating of its body and, as a result, the deterioration of the heat exchange process with the environment. It can be partially solved with the help of a fairly simple modification of the design.

To carry out the modification we will need a corrugated sheet of metal profile. It is necessary to make a kind of “jacket” for the stove from it, tightly fixing it on the surface of the cylinder by welding or in another accessible way. Such an improvement will contribute to the formation of upward convection air currents: cold air is drawn in from the bottom of the ribs, and hot air is released from above. In addition, you can additionally cover the entire structure with brick. This step will allow the walls around the stove to accumulate the heat it emits, heating the room more evenly and for longer.

Video instructions. Making a homemade pyrolysis stove “bubafonya” yourself

This publication will discuss the prototype of the bubafoni, the principle of its operation, the procedure for calculating the main parameters and how such a stove can be built even from auxiliary materials.

The name “bubafonya” sounds somewhat unusual to the ignorant reader, but meanwhile the popularity of this stove is very high. This is also explained by the fact that the design of its structure is quite simple, and the bubafon itself can be classified as a long-burning stove that uses fuel economically and does not require its constant addition to the firebox.

It is not only residential premises that require heating in private households. Many owners cannot imagine a single day without working, for example, in a workshop or garage, and in winter, without local heating, these buildings will be very uncomfortable. Heating may also be necessary in homestead farming - greenhouses, premises for pets and poultry.

Conducting a heating circuit from the house into such buildings is extremely difficult and wasteful. It is better to provide for the installation of stoves that can be heated as needed with solid fuel - firewood, sawdust, coal, etc. There are many similar options, and many of them are economical and easy to use. Stoves can be purchased in stores, but a good owner can always make one himself. One of these common crafts - baking bubafonya with your own hands.

Basic principles Bubafonya stove operation

The name “bubafonya” comes from the online nickname “bubafonja”, which belongs to the Russian master Afanasy Bubyakin from distant Kolyma. It is unknown whether he was the first to create a homemade stove similar design, but it was his model, the experience of assembling which he shared on the Internet, that became a kind of “hit”, a basis for imitation, a basis for their own developments and improvements for many home craftsmen.

According to the majority, the prototype for such a development was the design of a long-burning boiler from the Lithuanian company Stropuva, which gained wide popularity among Russian homeowners.

Stropuva boilers are produced in a fairly wide range of models, from S7 to S40 (the number indicates the heating power in kilowatts). However, all are characterized by a special shape - a narrow elongated vertical cylinder. This is not a whim of the designers - such a structure is determined by the very principle of operation of this boiler. The solid fuel loaded into it is ignited and burns from top to bottom. This is achieved by the fact that the air necessary for the oxidation process is supplied only to a thin top layer downloads.

The diagram shows a schematic diagram of the Stropuva boiler.

The combustion chamber (8) is loaded with solid fuel (firewood, sawdust, coal, briquettes) through special window (6).
Ignition of the top layer is usually carried out using flammable liquids. Then the air distribution device (7) is lowered onto this layer. It can be cross-shaped with special deflectors to supply air to a certain depth of the burning layer.

There are models with a distributor in the form of a crossbar, and recently disc-shaped ones have become widely used - who knows, maybe this was already borrowed by the designers of Stropuva from the Bubafoni, since such an innovation was introduced after the promulgation of its scheme.

In order for the furnace to operate stably, the supplied air needs certain preparation - heating to approximately 400 ºС. This process takes place in a special chamber (2). In the same chamber there is a special mode switch - a damper (4) with the “coal” or “firewood” positions.
The heating chamber is connected to the air distributor by a telescopic tubular channel (5), which extends as the combustion zone descends.

The combustion intensity is controlled by a damper (1), which regulates the amount of air entering the combustion zone. In the case under consideration, this happens automatically - a bimetallic spring is installed, changing its configuration depending on the heating temperature
Since “Strоpuva” is designed specifically for a heating system, a heat exchanger (water jacket) with pipes for return (11) and outlet of heated water (10) is provided.
A hatch (9) is mounted in the lower part of the housing for inspection and cleaning of the boiler from residual combustion products.

The combustion of the top layer of fuel with a dosed supply of air leads, in addition to direct heat transfer, to the release of pyrolysis gases, the afterburning of which, after the boiler enters normal operation, is carried out in the upper part of the cylinder, above the air distributor. After this, the exhaust gases are discharged into the chimney opening (3).

In fact, the boiler turns out to be a combined one, combining simultaneously the processes of direct combustion of fuel, pyrolysis and afterburning in one closed volume.

A Russian craftsman tried to implement a similar scheme. The main problem was the complexity of manufacturing a telescopic supply unit and air distribution device in the burning layer. However, a very original solution was found.

Approximate diagram of the structure of the bubafoni stove

The very complex air distributor has been replaced massive disk– a “pancake”, from the lower part of which deflectors are welded from a metal profile - channel or corner. This creates channels for the most uniform distribution of gas over the surface. This “pancake” with its mass presses the burning layer, and under the influence of gravity it gradually lowers as the fuel is consumed.
Now about the air duct. It was not made telescopic, but one-piece, from one piece of pipe, welded to the “pancake” of the air distributor. Thus, the air intake channel itself also gradually lowers - a kind of piston with a rod moving in the cylinder is obtained. For the free movement of the air pipe, a hole of the appropriate size and shape is cut out in the top cover of the stove, so that it does not impede the free movement of the entire structure, but at the same time does not leave an excessively large gap for air to “suction” from the outside.

Too tight an obturation, by the way, is not required in this place - a certain amount of oxygen must also enter the upper chamber of the stove - this is what is necessary for the afterburning of pyrolysis gases.

The lid is made in such a way that it fits as tightly as possible to the cylindrical body of the bubafoni. The air flow is regulated by a damper installed at the end of the air duct.

An outlet pipe is welded into the upper part of the housing to allow combustion products to exit, which is connected to the chimney pipe.

So, the scheme is very simple and seemingly uncomplicated - you can make a stove from any available materials. So it is, in principle, but if you approach this issue with the utmost seriousness, and in order to achieve highest performance efficiency and heating power, you should focus on the recommendations for calculating such a heating device.

Prices for the linear range of heating boilers Stropuva

Heating boilers Stropuva

Do-it-yourself bubafonya oven - calculating the main parameters

The dimensions of the main parts and assemblies that directly affect the operational characteristics of the furnace are shown in the diagram.

If you cannot find ready-made drawings for the manufacture of such a device, then you need to arm yourself with a calculator and carry out some calculations yourself.

1. Stove dimensions, that is, the diameter of the body (D) and its height (H), must lie in a certain proportion. The optimal ratio is considered to be from 1: 3 to 1: 5. Engineering thermal calculations show that in a stove that is too narrow, the incoming air simply leaves the combustion zone and is thrown into the chimney, which results in a significant loss of power of the unit. If you make the stove too wide, then it is difficult to achieve good results closer to the walls of the combustion body. Only the central part of the fuel filler will burn out; the pancake in this place will definitely sag and jam, and the combustion process will stop. The optimal furnace diameters are from 300 to 800 mm.

2. Δ – body wall thickness. This parameter is especially important if you plan to “dress” the stove in a water jacket, thereby turning it into a boiler. In this case, you should focus on a thickness of 4 to 6 mm.

In the case where the stove will only serve for local heating of the room by direct heat transfer, the wall thickness can be lower; bubafoni are often made from ordinary metal barrels. However, this necessarily leads to a loss of power - thin walls large area give a drop in temperature above the “pancake” and the effective afterburning of pyrolysis gases may be lost or significantly reduced. In addition, hot gases in the bubafon leak through a fairly narrow gap between the “pancake” and the walls, exerting a strong thermal effect on them, which is why thin sheet metal can quickly burn out. However, if you use metal of about 2.5 mm, for example, if the body is bent from a whole sheet, then this thickness will be quite enough to heat a garage or workshop.

3. Parameters of the air distribution devices. It is a mistake to believe that they are limited only by the diameter of the cut “pancake” - its thickness is also important, so How this part must have good heat capacity - it is in this area that the final heating of the supplied air is carried out.

Yes, for start - diameter disk. Calculations show that the optimal gap between it and the wall of the stove will be WITH = 5%D. For example, if the inner diameter housing cylinder is 400 mm, then a gap of 20 mm is required on each side, and we get a “pancake” Ø 360 mm.

Pancake thickness ( σ ) in practice is inversely proportional to its diameter. An excessively heavy unit will simply sink into the combustion zone, extinguishing the fire, while a unit that is too light will not create reliable pressure. And this may end in ignition of all the fuel or even reverse combustion, for years the flames will come out through the supply air pipe, and the air flow will go through

The approximate thickness of the steel “pancake” is given in the table:

The height of the ribs of welded air ducts (channels, angles or steel strips). There is no clear linear dependence, but you can focus on the following values.

If a cylinder of a different diameter is being manufactured, then the thickness can be easily calculated proportionally, bringing it, of course, to the standard thicknesses of manufactured metal sheets.

However, if you want to make a truly efficient stove, then it is better to make them in the form of blades curved in a clockwise direction - the air path in this case increases, improving the uniform combustion of fuel on the surface, and, in addition, a directed turbulent flow appears, which contributes to the most complete combustion of pyrolysis gases. The very design of the created air channels. The simplest thing is a cross-shaped arrangement of channels with side shelves of the required height.

And this is a completely unsuccessful example of making an air distributor

And this is an example of what should never be done. The edges of the “pancake” are not processed, the metal is very thin, and the corner shelves, on the contrary, are extremely high. In essence, the entire bubafoni effect is lost - most likely, such a part will lead to extensive combustion of the fuel filler.

4. The next most important characteristic is chimney outlet diameter, or more precisely, its cross-sectional area (in the diagram - S).

This parameter is calculated by professionals using rather complex formulas that take into account many characteristics. However, practical experience in using such furnaces allows us to somewhat simplify the calculation procedure, and the calculations can be carried out independently.

Basic formula: S=1.75 E

— S – cross-sectional area of the chimney pipe.

— E – energy output of the stove per unit time (kW/h).

The quantity itself E is determined by the following formula: E=M × e.

—M– mass of fuel added to the stove.

— e– specific heat transfer of a particular type of solid fuel.

The mass of the bookmark is calculated based on the volume of the working part of the stove and the weight coefficient of the type of fuel, i.e. its specific mass per unit volume.

M = Vf × mf.

—Vf– volume of the fuel compartment of the stove (dm³).

—mf– fuel loading coefficient (kg/dm³).

Indicators e And mf are reference values. For example, this data for some common types of solid fuel are given in the table:

View solid fuel	mf – specific filling factor, kg/dm³	e – specific heat transfer, kW/h
standard size firewood, aspen	0,143	2,82
pine shavings or sawdust	0,137	3,2
alder pellets	0,285	3,5
DPK grade hard coal	0,4	4,85
SSOM grade coal	0,403	5,59
coarse anthracite	0,5	5,72
peat briquettes	0,34	2,36

For example, you can take the calculation of the chimney cross-section for a homemade bubafoni from a regular gas cylinder, which D= 300 mm, Nf= 600 mm. Remains Another value is the volume of the loading chamber. Its height (in the diagram - Nf) is usually taken as ⅔ of total height stoves N. The volume is calculated using the usual formula - the cross-sectional area of the cylinder multiplied by the height: Vf = πD²/4× N f.

Vf =π × 3² × 6: 4 = 42.39 ≈ 42 dm³.

The calculation of thermal characteristics always follows the fuel that will give maximum heat transfer. In this example, let’s take SSOM coal:

Total weight of the stove loading with coal: M= 42 × 0.403 = 16.92 ≈ 17 kg.

Burning such a mass of fuel in an hour will produce the following amount of energy:

E= 17 × 5.59 = 95.03 – can be rounded to big side up to 100 kW.

Thus, the cross-sectional area of the chimney for the stove in question is required:

S= 1.75 × 100 = 175 cm². From here it is easy to calculate the diameter of the pipe - in this case it will be 14.93 cm or, when reduced to the standard pipe size, 150 mm.

By the way, such calculations can also give an idea of what the average power of the stove will be. In our case, 100 kW was received. Practice shows that with a properly assembled unit, it works on one load for about 12 hours. Thus, we get 100 / 12 = 8.33 kW/h.

5. Basic parameters of the air supply pipe. Its diameter ( on the diagram – d) with some strengthening ÷ can be taken as 0.5 ÷ 0.55 from the diameter of the outlet pipe. Thus, in the example under consideration, a 76 or 80 mm pipe can be used.

The pipe will be welded into the “pancake” of the air distributor. It is recommended that its lower edge be placed at the same level as the lower edges of the air guides. To avoid excessive air flow in the center, which can create an unnecessary cone-shaped zone of enhanced combustion, the outlet hole of the pipe can be narrowed, for example, by welding an unnecessary steel gear with a narrow mounting hole here, and the main air flows can be redirected between the blades (channels). So distribution air masses will go more evenly.

— The gap between the pipe and the collar ( δ ) should be no more than 2.5 mm.

— Collar height ( L) should be minimal 80×δ .

— When the “piston” is completely lowered down, the air duct pipe should rise to a height above the upper edge of the collar q = L + 150.

In our example we get the following:

Let’s say that after making a collar cylinder (usually they are made from galvanized sheet) and trying it on a pipe, pressing it to one side, we get a clearance of 2.4 mm. Thus, the gap created δ it turns out 1.2 mm on each side.
Based on this, the collar height ( L) must be at least 1.2 × 80 = 96 mm.
The part of the pipe protruding above the collar is q= 96 + 150 = 246 mm.

Of course, the obtained values can be rounded up, to 100 and 250 mm.

On the upper section of the pipe, it is necessary to consider a movable damper, which, moving around its axis, will be able to operate in the full range - from completely closing the pipe lumen to completely opening it. It is this damper that will be the main “control element” of the stove - it regulates the amount of air supplied to the fuel combustion zone.

If it is planned to be multi-fuel, then a similar damper is often installed on the top cover of the stove. To burn pyrolysis gases emitted by some types of fuel, an additional “portion” of air may be required.

6. Additional parameters of the bubafoni stove. These parameters, in principle, do not determine the operational characteristics of the stove, but they must be taken into account at least so that the bubafonya is most convenient for everyday use and maintenance. These include:

The distance from the top edge of the stove body to the insert of the chimney pipe and the loading door (in the diagram - i).

Calculated using the formula i =h+σ + 20 mm.(the meaning of all symbols has already been mentioned in the text above).

The height of the bottom edge of the loading door from the bottom edge of the cylinder (in the diagram - Hmm).

Hm = Hf +h+σ + 30 mm

This makes it possible to carry out an inspection and periodically clean the lower surface of the “pancake” from soot deposits.

Based on the calculations performed, it is easy to determine the height of the loading door:

hm = H – Нf –i.

In this case, the width of the opening should not be more than ¼ of the circumference housing cylinder stoves.

It is also necessary to provide a technological door to clean the stove from combustion passages (ash pan). It must be wide enough, since when coal is used as fuel, caked slag can accumulate at the bottom of the cylinder, which can be removed by pipe.

Door height ( ha) is calculated as follows: ha =h+ σ + 100÷150 mm.

The width of the opening is the same as that of the loading door.

To avoid air leakage through the doors (hatches), they are made in two layers with a mandatory seal made of asbestos sheet or basalt cardboard. The opening itself is framed with a box-shaped neck, onto which the hatch hinges are welded.

By the way, many performers removed the cover and removed the “piston”. There are fewer maintenance conveniences, but the work of making bubafoni is greatly simplified. To somehow facilitate the loading and cleaning process, handles are welded to the stove lid.

7. Bubafoni installation parameters. When drawing up your own design for a bubafoni stove, you should definitely calculate the main parameters of its future installation and connection to the chimney pipe.

Basic principles are shown in the diagram, however, a few more clarifications should be given:

Approximate installation diagram for the stove - bubafoni

It doesn’t matter whether such a stove will have welded legs, or whether it is simply planned to be placed on the lower end part, the base must have pronounced fire-resistant qualities. The combustion of fuel in the stove-bubafon goes all the way to the lower boundary of the cylinder, and the bottom, of course, becomes very hot from this. An ordinary concrete screed will not suit you in any way - crumbling and cracking will certainly begin soon. This means that you will need to build a kind of “podium” from fireproof fireclay bricks.
The height of the chimney pipe must be at least 4.2 m, otherwise the draft quality will decrease, which will give sharp decrease heat transfer due to the defective process of afterburning pyrolysis gases in the secondary chamber - the furnace will simply “suffocate”.
The size of the horizontal section of the chimney, before inserting into its vertical part, should be no more than 400 mm. It is also not recommended to bring it too close - the thermal equilibrium of the system may be disrupted.
The pyrolysis process is always accompanied by a fairly significant release of water vapor, and, even in the case of well-dried firewood. To avoid the accumulation of water condensate on the inner walls of the chimney (and this sometimes even leads to complete freezing of the pipe openings), a special knee - compilation moisture. Its height from the insertion point is at least 300 mm. A drain valve must be installed at the bottom for regular maintenance - draining accumulated liquid. It is better to install a ball valve - this will make it possible to clean the clogged drain hole with a piece of thin wire.

Perhaps, for some, such calculations for the bubafoni stove may seem overly cumbersome. However, this is not at all difficult - it’s worth devoting several evening hours to such a process, armed with, and own project, based on an almost scientific approach, will be ready. But you won’t have to doubt the performance of the heater in trouble.

By the way, you can even start from materials available in the household. The publication already mentioned an old gas cylinder - this is an almost usable blank for the body.

Bubafonya stove made from a gas cylinder...

Knowing the parameters of this cylinder, it will be easy to “adjust” all other parts and components to it.

... and its dimensional parameters

If you have good skills in working with metal and the ability to use sheet-bending equipment, then you can create your own project “from scratch”, with exactly the dimensions and power required to heat a particular room.

Prices for sheet metal bending machines

Plate bending machine

Video: bubafonya stove from a gas cylinder

One of the simplest options is bubafonya from a barrel

And finally, a little about how you can make a simple bubafon from such widespread auxiliary material, like an unnecessary metal barrel, which, however, retained the integrity of the walls.

The thickness of the metal of the barrels is small, and, of course, it will not be possible to obtain too significant heat transfer from such a bubafon. Its efficiency is also not very significant, but the large loading volume and the duration of operation on one “refueling” up to 12 hours are what is needed for heating some outbuildings or utility rooms.

Another convenience of this design is that the barrels have a single standard size. If the most vulnerable area, the walls, burns out (which is bound to happen sooner or later), it will not be difficult to quickly make a replacement, since the remaining parts - the cover and the air supply system, which are less susceptible to rapid wear, can easily be rearranged into a new housing.

So, first of all, you need to remove the top cover of the barrel. It is best to carefully cut the weld seam around the circumference with a grinder - and the cylinder will have a smooth edge, and the lid will have a flared “skirt”.

Prices for popular brands of portable welding machines

Portable welding machine

The edges of the barrel are driven slightly inward with a sledgehammer, and on the lid, on the contrary, the lining is expanded.

The edges of the body are processed...

...and the cut off lid

As a result, the lid should fit tightly on top of the body.

If there is a plug on the lid, it can be scalded, but often this hole is left for a second air damper.

The lid can be made a little differently. In this case, it is cut to such a diameter that it fits tightly into the housing cylinder. A metal plate of arbitrary size and shape is welded on top - it will become both a support and a kind of “slab” on which you can put a kettle or a bucket to heat water.

An air supply is cut out in the center of the prepared lid. You must try to keep the edges as smooth as possible.

The air distribution device is being prepared. Usually for it they take the same lid from another barrel or cut out a blank from a metal sheet. If a sufficiently thin-walled metal is used, it is recommended, if possible, to make bends downwards around the circumference - this will reduce the risk of deformation of the disk during strong heating. Cuts through the workpiece round hole where the air supply pipe will be welded.

Metal profiles – air ducts – are welded from the bottom of the “pancake”. The figure shows a channel, but with such a large diameter of the stove, it is still preferable to choose the option with curved blades made of a metal strip - the air distribution process will be much more efficient. This, of course, will require more time, but it is worth spending it to increase the productivity of the furnace.

The resulting “pancake” is welded to the air supply pipe.

An air damper mounted on the axle is attached to the top of the air supply pipe. For ease of operation, it is recommended to provide for fixing the position of the damper in the desired position, for example, with a wing nut.

A more advanced damper - with a locking “wing”

A hole is marked on the stove body for inserting the chimney pipe.

When welding a chimney pipe, be sure to ensure that the seam is completely sealed.

In fact, all bubafoni nodes are already ready. unless, of course, you count the chimney. All that remains is to assemble the stove by installing the “piston” of the air supply system into it and closing the structure with a lid.

As already mentioned, for convenience, you can weld the handles both to the lid and to the stove body itself.

Video: version of the bubafoni stove from a barrel

If you wish, you can “dress” the bubafon stove in protective metal screen, which is mounted on short stands welded to the body.

Another option is to wrap the body with a profiled sheet with a sufficiently high wave height. In both cases, this will have a double positive effect:

The risk of getting an accidental burn from the hot stove body will be significantly reduced.
This design will create a powerful convection flow, which will help quickly warm up the room.

Those discussed in the article are basic, and each master can make his own changes in compliance with the basic fundamental parameters. There is a very wide field for creativity and experimentation here. For example, in the presented video, the author shares his own improvement bubafoni

balanced power;
good efficiency;
economical;
non-volatile;
compact;

The heat exchanger must be purchased separately.

STROPUVA S 40

The best long-burning boiler of 2019, capable of providing heat to the hearth for 70 hours. This will require about 50 kilograms of firewood. Not very economical, but very convenient and effective. For country houses there is no better option. By the way, do you often see 95% efficiency? So, this model has the following indicators. Heats up to 400 square meters. Operates on coke, wood, coal. Judging by user comments, this model fully lives up to expectations, despite the high price tag. Attracts with stability and efficiency.

has low fuel consumption;

retains heat for a really long time;

compact - does not occupy a large area.

the window for loading briquettes, coal and firewood is located low - skill is required;
The unit is quite heavy - help is needed to move it.

Stropuva Mini S8

The small solid fuel boiler Stropuva S15 is attracting increased interest from summer residents and owners of commercial buildings. It is capable of heating rooms of 150 square meters. m. One stack of firewood allows you to maintain heat in the house for 30 hours, and when using coal this time increases to 5 days. Economical fuel consumption is complemented by a high level of efficiency of 85%. The device is capable of heating the coolant to a temperature of 95°C, which is higher than that of its competitors.

high efficiency;
high coolant temperature;
long burning of fuel.

slight pressure;
mechanical control.

Updated:

2016-08-29

The Bubafonya stove is an economical way to warm your own house or cottage when cold weather sets in. When you rarely visit a country house, it is not always reasonable to equip it with expensive heating equipment. The solution to the problem is homemade heating stoves. A striking example of such a device is Bubafonya.

A distinctive feature of Bubafoni is that in a fairly simple design the developer managed to combine all the main qualities of the stove:

A simple stove design that allows you to build Bubafonya with your own hands;
Small amount of fuel consumed. There are many homemade stoves, which do not differ in efficiency and productivity. Afoni's project succeeded in this regard;
A minimum of attention during the operation of the furnace.

The design of the furnace includes three main elements:

Lid;
Piston;

With one load of fuel, the stove can operate continuously for 24 hours. Modern modifications of Bubafoni make it possible to heat entire private houses at low air temperatures outside the windows. Such stoves are suitable for use at home, garages, and greenhouses. There is no need to worry about a fire hazard from Bubafoni, since the design of the stove in this component provides reliable protection.

How Bubafonya works

Scheme of operation of the bubafonya stove

The main feature of Bubafoni compared to traditional stoves is the location of the fuel in the upper part of the structure, and not in the lower;
When fuel burns, the heated air descends;
But during the period when the air is still at the top, it helps to dry out the wood, which then heats the stove;
The design of the fireplace includes a protective screen. It does not allow fire to spread throughout the entire cylinder;
There are gaps around the device, which ensures uniform combustion of fuel;
Due to the damper installed on top, the user can adjust the intensity of firewood combustion;
To stop the heating process, you simply need to close the damper completely. This will stop oxygen from entering the firebox, which will lead to the flame dying out in just a few minutes.

Advantages and disadvantages of the stove

We have already outlined the main three advantages of the Bubafoni stove. In addition, there are several other strong qualities of a homemade stove.

A minimum set of tools and materials will be useful to you when self-production Bubafoni. Many make do with improvised means, since you can find the same cylinder for the body on your site or ask your neighbors. Previously, many houses in villages and suburbs were equipped with bottled gas stoves. The main gas supply has been supplied, and the cylinders may remain somewhere in the garage.
Efficient heating. The simplest design of the Bubafoni stove itself can heat a room. If you improve the design a little by connecting a water jacket, the stove will be able to heat the entire house.
Compact sizes. Bubafoni does not require much space, plus it is mobile. If necessary, you can move the stove to another room. Although stove models with a water jacket are limited in movement, since they are connected to pipes.

Despite the objective advantages of the stove, there are some disadvantages that are worth paying attention to:

Although the Bubafonya stove will not take up much space, the chosen room must have effective ventilation. Although this rule applies to many heating devices, therefore there should be no problems with providing ventilation;
After the firing procedure, the stove cools down quite quickly. Considering the fact that the Bubafonya stove is capable of operating autonomously for up to 24 hours, such a drawback does not cause much disappointment in Bubafonya.

Making Bubafonya with your own hands

There is nothing complicated about making Bubafoni yourself. But think carefully before using just such a stove to heat your home.

The heating equipment market offers many ready-made options for stoves that effectively cope with space heating tasks. Some of them are quite affordable, others require significant investment.

If the analysis showed that Bubafonya will be the objectively best solution for your dacha, then it makes sense to assemble it yourself.

To make a Bubafoni stove you will need:

Bulgarian;
Channel;
A pair of heat-resistant steel pipes;
Barrel or gas cylinder. It is advisable to choose a container of 200 liters;
Hacksaw for cutting metal;
Hammer;
Welding machine.

As you can see, the construction of the Bubafoni stove does not require any special tools or materials that cannot be found on backyard or on the market.

When everything is ready to go, you can take the step-by-step instructions as a basis and assemble a rather unique heating stove with the original name Bubafonya.

Carefully cut off the top of the barrel of the future stove. Try to make the cut even. When burrs appear, it is better to sand them down.
By cutting out the top you will get a circle. A round hole is cut in it. Its diameter is approximately 10 centimeters. Please refer to the pipe dimensions as they may vary.
Weld the pipe to the hole, being careful to make tight seams. Working with a welding machine requires compliance with certain safety rules. Don't ignore them.
Weld 3-5 channel elements crosswise onto either side of the circle. How do you make the lid heavier, which will ensure the necessary fit to the stove structure? Due to the weight of the lid, the fuel will be pressed down, and oxygen will be able to flow into the combustion chamber. This is the basis for achieving a long burning effect.
A hole for the door is cut at the bottom of the barrel. Fuel will be loaded into Bubafonya through it. A rectangular combustion hole is cut out with a grinder, after which the curtains are welded to this metal element. It is better to choose thick metal for them.
Make another cutout slightly below the combustion hole. rectangular shape. But its size will be slightly smaller. This hole in Bubafon will allow the extraction of ash generated during fuel combustion.
To remove smoky gas from Bubafoni and create the necessary draft for the stove, cut another hole on the side. Its size must correspond to the diameter of the selected steel pipe.
Make an elbow from the chimney pipe of your Bubafoni stove. This is an element made at an angle of 45 degrees. You can buy a ready-made structure, or cut an existing pipe into two parts, make a cut at an angle and weld the two elements at the joint. The angle between the parts of the Bubafoni chimney pipe should be straight.
One of the sides of the resulting elbow is welded to the side opening of the stove.
If Bubafonya is located indoors, another pipe is welded to the chimney, which is led outside the house. This will allow the smoke to escape into the atmosphere. Make sure all connections are tight to prevent smoke from getting inside the house.
At the bottom of the stove Bubafonya will get very hot. Therefore, it is advisable to install the stove on a foundation made of refractory bricks.
Install a reflector near the Bubafoni stove, which will improve uniform heating of the premises and increase safety.

The slow-burning heating stove “Bubafonya” is the creation of a craftsman from Kolyma (a resident there in our days, not Stalin’s) Afanasy Bubyakin. He shared his successful experience online, where his nickname is bubafonja, which is how the stove got its nickname. For the prototype, Afanasy took the Lithuanian-made Stropuva boiler, which, no matter how much it was criticized at times, has proven itself to be excellent over almost 15 years of industrial production.

Today, bubafonya can be said to be the favorite brainchild of amateur stove makers. After Bubyakin’s modifications, which will be discussed in more detail below, he can do it himself home handyman almost any qualification, as long as they know how to operate a welding machine. You can “bang” a bubafonya in a weekend, and for many people the Kolyma stove works properly and the sheds are almost free (see figure): the bubafonya heats well on almost any solid fuel, from pine sawdust to anthracite.

Homemade stove “Bubafonya”

This has given rise to many attempts to adapt bubafonya for water heating at home: the price of a 20 kW Stropuva boiler exclusively wood-fired in the Russian Federation is currently approximately 90,000 rubles, and a universal wood/coal boiler is about 120,000 rubles. Analogs, which will be discussed later, cost 68-110 thousand rubles. Not cheap either.

However, if for Stropuva boilers since their appearance on the market in 2001, not a single complete or sudden failure has been noted, then with water-heating bubafons fiasco follows fiasco. The stove works, ignites, heats, but:

Fuel consumption corresponds to an efficiency of 60% at best.
Carbon deposits intensively form on the walls of the fuel chamber.
When the weather changes, you have to run to the boiler room every now and then to manually adjust the air supply. You gape - the temperature of the coolant in the system for 15-20 minutes. jumps to 95-97 degrees, and this is already on the verge of boiling with all that it entails.
The heat transfer time from one fuel load is up to 12 hours versus 30 or more for the Stropuva.
Water condensation in the chimney forms so abundantly that in severe frost it freezes and blocks the chimney.
Cases of “backburning” have been observed, when the stove draws air through the chimney, and a flame shoots out of the duct.

In general, a bubafonya with a water circuit works more or less reliably and stably only when taking up to 10-15% of its thermal power for hot water supply, and desperately resists attempts to take more for heating. I must say that bubafonya as bubafonya is not to blame here. It needs an internal supply of heat to properly burn off the exhaust gases (a mixture of pyrolysis and flue gases).

This is a characteristic feature of any. Nevertheless, thanks to knowledge of the physical and chemical processes occurring in it, it is still possible to adapt such a stove to a heating boiler, as Lithuanian designers proved at one time. And the purpose of this article is to figure out how to wean the stove from greed for heat in relation specifically to Bubyakin’s design.

The end result is ambiguous. On the one hand, the Bubafonya cauldron is still possible. On the other hand, you still need to think and think, try and think again. Especially with automatic operation and a wood/coal switch. But we're getting ahead of ourselves.

Prototype

What was Afanasy coming from? Let's look at the example of the best-selling Lithuanian model - the wood-burning Stropuva S20 with a thermal power of 20 kW, see fig. Universal boilers look exactly the same, but the index U is added to the name, for example. StropuvaS20U. They are sometimes, as in this case, installed as backup in the elevator units of private houses and low-rise buildings, in order to at least avoid defrosting the system when the central heating is turned off.

The Stropuva boiler diagram is shown in Fig. lower left. It has several differences from the then (2001) design of surface combustion furnaces and boilers. The first is air preheating chamber 2. It is supplied to the fuel at a temperature of about 400 degrees, which ensures combustion together with pyrolysis and effective afterburning of exhaust gases.

The second point is that air enters the fuel from above through a hollow telescopic rod 5 with an air distributor 7 (see next figure on the right). The distributor is a complex configuration of a cross with a deflector (“ears”) for supplying part of the air to a certain depth into the fuel mass and an air capillary.

This design ensures that the oxidizer is supplied precisely into the thin burning layer continuously as the fuel mass settles. As a result, complete combustion of the fuel occurs in a small vertical zone above and below the air distributor. Already burnt out, but still very hot flue gases swirl a little higher; their heat can be used in any way without disturbing the thermochemical cycle of the firebox. In essence, "Stropuva" - combined type, in which combustion, pyrolysis and afterburning of pyrolysis gases are combined in time and space.

Combustion in such a system is unstable; If after ignition you leave the air supply at maximum, the fuel will ignite. An economical slow combustion mode is provided by an air throttle (damper, item 1 in the diagram) driven by non-volatile thermomechanical automation. In slow-burning heating boilers, mainly two of its schemes are used: on bimetallic plates and lever-differential.

About thermomechanics

The principle of operation of thermomechanics on bimetal (thermosprings) is based on the difference in temperature expansion coefficients (TCE) of different materials, see fig. The smaller the initial angle of divergence of the plates α, the greater the bending of the spring will be at the same heating. Therefore, thermal springs are most often made from plates sintered along the entire plane by contact welding, resulting in a bimetallic plate. With slight heating, less than 100 degrees, it literally bends in an arc with great force.

Thermosprings (thermobimetallic plates) do not require complex kinematics of the damper drive; a spring made of plates 300 mm long and α = 3-5 degrees when heated to 85 degrees pulls with a force of several kilograms. But thermal springs made of ordinary materials, due to large internal stresses, quickly get tired: the temperature in the system has to be adjusted using a thermometer approximately once a month, and every season or two the spring (plate) needs to be changed; it bends forever.

For an industrial product intended for the market, such operational conveniences mean death before birth, but homemade thermal springs may come in handy for craftsmen. In this case, you need to take pairs of stainless steel - brass or, better, stainless steel - bronze. Stainless steel - beryllium bronze pairs work accurately and stably for years, incl. in military equipment, but beryllium bronze is a strategic material of strict accountability. In factory boilers, and in the same “Stropuv”, bimetallic plates made of special alloys are used.

Soft metals with large TCR (copper, aluminum) are not suitable for thermal springs. They are sometimes used in bimetallic plates that operate rarely occasionally, for example. in self-resetting electrical circuit breakers.

The plates for a homemade thermal spring should be trapezoidal, with a wide base of 30-50 mm and a narrow base of 10-15 mm. The height of the trapezoid is 200-300 mm. The plates are riveted with narrow bases. An additional lever with a shoulder ratio of 1:3 - 1:5 (on the right in the figure) will give a working stroke of 120-130 mm, which is enough for an air throttle.

The thickness of the plates should be from 0.5 mm, and different for different metals: less elastic - thicker. For 0.5 mm of stainless steel you need approximately the same amount of beryllium bronze, 1 mm of ordinary tin bronze and 2 mm of brass.

Sometimes factory-made boilers use differential-lever thermomechanics. The principle is the same, but unequal heating of the same material is used. Namely - the inner and outer walls of the water jacket; the difference is monitored by a pair of long-armed levers hinged at one point. The lever-differential system is durable and stable, but requires quite complex kinematics from precision parts, because the linear difference in the expansion of the boiler shells is a fraction of a millimeter.

Returning to “Stropuva”, it remains to talk about the wood/coal switch and the features of the boiler piping. Initially, the Lithuanian boiler was designed for oil shale, which the Baltic states are rich in. Slate burns about the same as wood, so Stropuva was used for firewood without significant modifications.

But there were problems with coal: for afterburning of its exhaust gases it is necessary extra air. It was taken from an air heater, installing a valve in it with manual control, but the vacuum in the afterburning space turned out to be insufficient for the required suction. It turned out to be impossible to solve the problem just like that; for the coal-fired furnace, it was necessary to make a boost from an electric fan at the rate of approximately 1 W of electric for pressurization per 1 kW of heat transfer from the boiler. However, this has a silver lining for manufacturers: the boost fan is not included in the kit of the universal boiler; it is supplied optionally. For a fee.

That is, the coal-fired Stropuva has lost its energy independence; this must be remembered when planning a purchase or trying to replicate the design. And the load from some types of coal does not burn out completely. The residue is suitable for afterburning in the next load, but it has to be raked out of the ash pan and the fuel must be separated from the ash.

When using coal, Stropuva provides heat transfer for up to 5 days. Today this indicator is very average: ultra-long-burning coal boilers on one load heat up to 30 days and allow you to reload fuel without stopping and disturbing the combustion mode, i.e. They need ignition once a season. But they only work on coal.

Harness

The Stropuva boiler piping is special: it is not suitable for other types of boilers, and vice versa. Here the Lithuanians must be given their due: the scheme is well thought out taking into account the heating features of residential buildings, is simple and relatively inexpensive, which largely compensates for the high cost of the boiler itself. The wiring diagram for S20 in the simplest version, without heated floors, is shown in Fig.

The first thing that attracts attention is the separate register R1; it is marked in red. This battery is placed in a room where an even temperature regime is not necessary: in the hallway, on the staircase. In cold weather (at the boiler maximum), the balancing valve bk1 is adjusted so that the radiator is slightly warm.

The temperature (not thermal!) inertia of the boiler is 20 degrees, and the time inertia is about 20 minutes. That is, if the standard thermometer on the boiler is set to 70 degrees, then the temperature of the coolant within 20 minutes can change from 60 to 80 degrees. During this time, excess coolant is transferred to R1, which thus plays the role of an emergency radiator, but without disturbing the combustion mode and reduction in efficiency boiler

The second thermal buffer is DHW boiler B; It is strongly not recommended to operate the boiler without it. Bypass valve 3 sets the temperature of the DHW water, and the same below, according to the diagram, sets the temperature of the general-purpose registers.

The return flow bypass device TZ-20-50 is standard. Its purpose is to prevent the return flow from cooling below 45-50 degrees, otherwise acidic condensate may form in the boiler due to overcooling of the afterburner.

The second balancing valve bk3 works in tandem with a 40-80 W circulation pump P, ensuring optimal circulation speed in the boiler jacket and registers separately. If the pump has automatic speed control according to the supply temperature, then bk3 is not needed, so it is supplied optionally.

This scheme does not require regular recharge from the water supply, and drain 5 is used only when re-energizing, so there is no float valve at all. But the system must be completely sealed, so it is possible to install only a membrane expansion tank H. Its second, however, relative, inconvenience is that the maximum pressure in the boiler is 2 bar, and the drain safety valve is set rigidly at 1.5 bar. That is, no pump will drive the coolant above the 2nd floor, and even there the batteries will be colder than on the first floor.

Is Stropuva good?

To the above disadvantages, of which the main one is slow heating (20 minutes for the boiler itself, but the whole system?), it is necessary to add the following:

Impossibility of technological shutdown: the fuel load must burn out completely, only then can any work be done on the boiler and system.
Impossibility of reloading fuel without re-ignition.
The efficiency declared by the manufacturer (91.5%) does not correspond to both the values declared by dealers (85-87%) and the results of statistical processing of fuel consumption from real users, 76-78%
A separate boiler room is required for the boiler according to the requirements of the Ministry of Emergency Situations (from 8 cubic meters, ceiling from 2.2 m, made of non-combustible materials, an openable window, an unobstructed supply window for air, a separate smoke duct).

Nevertheless, “Stropuva” is taken very willingly. The reasons are by no means marketing and advertising tricks:

Exceptionally high reliability of the boiler, inherent in the very principle of its design. In the outback in a frosty winter, this is certainly more important than a few percentage points of efficiency. Minor faults are easy to fix, do not cause the boiler to stop and make themselves known in advance.
If there is a loss of electricity, the boiler itself switches to thermosiphon circulation without any outside intervention and can operate in this mode for an unlimited time with a normal fuel load. The house will be a little cold, but the system will not defrost.
Simple and inexpensive harness.
The piping scheme, if an indirectly heated DHW boiler (with a built-in heat exchanger) is installed, allows you to fill the system with antifreeze without recharging for 5-7 years or more.
Installation of the boiler does not require a fireproof base or reinforcement of the flooring, as long as it is fireproof.
Large power adjustment limit, more than 10 times.
Real efficiency remains within the power control limit of 100-10%.
As a consequence of the 5 previous points, cost-effectiveness both during commissioning and during it.

Analogues of "Stropuva"

Although today “Stropuva” is far from the last word in heating engineering, in terms of technical specifications, operational qualities and environmental requirements, the boiler remains at the level of modern requirements, and its design has been proven and time-tested. It is not surprising that, using Lithuanian licenses, many companies produce analogues of Stropuva on the same principle: Atlantic, Beretta, Candle, DEMRAD, Electrolux, Eurofan, FLAMINGO, FONDITAL, GLOBAL, HERMANN, Junkers, Liepsnele, LG, MIDEA, NOVA FLORIDA, Protherm, SIME, Starway, VAILLANT, Viadrus, Viessmann.

Well-known domestic manufacturers do not take Lithuanian licenses, it is difficult to obtain. But instead, on the Russian market there is a line of KVR boilers (trademark “Tverdotop”, see the figure on the right) from the “Bear” concern, which are inferior to “Stropuva” in terms of operating time, but in some ways superior to the Lithuanian:

The price is 20-25% lower with comparable technical data. For a 20 kW wood boiler, 68 thousand versus 85.
The permissible length of firewood is up to 35 cm for 10 kW KVR, 40 cm for 20 kW and 45 cm for 40 kW. The “Lithuanian” needs to be drowned with lumps of wood.
Loading door height 940 mm; The entire stacking of firewood is right in front of your eyes, you can correct it at the bottom without touching the top.
The air distributor lifting mechanism is combined with the door and assembled on rollers. In Stropuv, the lifting cable is stretched in a tube: it’s harder to pull, and the tube wears out over time.
The ash pan door is foolproof, which eliminates the fire hazard.
The doors are non-scalding and the seals are hard to wear out.
There is a damper on the chimney, i.e. the boiler can be connected to any existing pipe with excess traction.
The permissible pressure in the system is 2.5 bar, which allows heating 2 floors with an attic within sanitary standards.

At the same time, “Terdotop – Bear” is not without noticeable shortcomings:

The minimum height of the boiler room ceiling is 2.5 m; the boiler itself is very high.
The heat transfer time from one load of firewood is 20 hours versus 30 for Stropuva.
Top exit to the chimney. If you make an opening in the wall for the pipe, which is easier than in a concrete ceiling, then you will need to further increase the height of the boiler room and install an extra bend that requires cleaning.

In general, KVR and Stropuva cannot be called enemies; both are designed for their own operating conditions. “Stropuva” is a more or less inhabited place with developed standard construction and a climate closer to European. KVR will be more effective in conditions of a sharply continental climate in areas where everyone is building more independently.

“Slow kettle” or pyrolysis machine?

It turns out that pyrolysis in slow-burning boilers is barely visible somewhere in the area of the air deflector? And does this affect its quality indicators? Yes, and purely with separate gasification and combustion it is superior to slow burning boilers in the following parameters:

High efficiency; 95% is normal.
Stable operation on any type of fuel: two-stage combustion with feedback the process is fundamentally stable.
Compact: 20 kW boiler the size of washing machine, it can be simply placed in the kitchen, as long as the firefighters allow it.
Environmental friendliness: the exhaust produces only CO2 and H2O, which in principle allows firefighters to issue operating permits without a separate boiler room.

But the widespread distribution of “pyrolysis machines” is also hampered by serious disadvantages:

High cost, approximately twice as high as a “slow” boiler of the same power.
Small limits of power adjustment: superiority in efficiency in real conditions when the weather changes is often emitted into the world by an emergency radiator and flows into the sewer by discharging the overheated coolant.
Limited service life of the heat-resistant lining of the combustion chamber, i.e. Regular and expensive repairs are required.
Complete energy dependence: without fan pressure and power supply to the control automation, the boiler simply goes out.

In general, the pyrolysis boiler is still only a good prospect. He will have his say when the developers deal with its shortcomings, and the increased price of fuel will force the percentage of efficiency to be calculated.

Let's take on Bubafonya

Now let’s find out why the Bubafonya stove is so popular. What did Bubyakin contribute to the original design that made it repeatable using the simplest means at home while maintaining parameters comparable to the branded ones?

But then there is no way to attach an air heater, and heating of the incoming air is necessary, otherwise you won’t expect decent efficiency. In the Kolyma region this is by no means an abstract question.

Bubyakin also solved this problem in the spirit of the entire furnace: he replaced the complex air distributor-deflector with a rather heavy pressure “pancake” with ribs at the bottom. In this way, it was possible to drive almost the entire working process under a pancake: with its weight it compacts the burning layer and the air has time to warm up properly literally centimeters from the mouth of the air duct. This allowed correct execution stove and its proper operation to avoid reverse combustion, at the same time reducing the height of the stove by almost half and maintaining an efficiency of over 70% in such an extremely simple design (see figure on the right). Thermal power is regulated, as in Stropuv, by air supply.

The exit of exhaust gases for afterburning was also ensured in an extremely simple way: into the gap between the “pancake” and the furnace wall. The share of pyrolysis in the area under the pancake in the Bubyakin oven increased; Accordingly, the role of afterburning in the space above the pressure increased. This and some other circumstances, see below, explain the difficulty of adapting bubafoni to a heating boiler.

Interesting fact

Soon after the description of bubafoni appeared on the RuNet, Stropuva announced an important improvement: an air distributor of a new design, see fig. on the left, allowing you to add several percentage points to the efficiency. I wonder if they even wrote to Afanasy himself in Kolyma about this?

Where can I get the drawings?

You can’t find accurate information about the correct proportions of bubafoni in free sources, and paid ones completely avoid this topic. It’s understandable, this stove is made mainly from improvised rubbish, whoever thinks and can. Of course, there is no need to wait for the maximum parameters that the idea itself can provide here.

Well, let's take on the design ourselves and, after rummaging through the available pieces of hardware, we will develop the drawings ourselves according to our needs and capabilities. Take a look at fig. How many different sizes are there (the defining ones are highlighted in color)! And how are they related to each other?

Among Murphy’s laws, which after Murphy himself were compiled into a rather thick brochure, there is this one: “Any simplicity is only the visible part of hidden complexity.” But don’t be embarrassed, now we will explain everything to you in such a way that constructing the stove will take no more than an evening.

The main proportion is the ratio of the internal diameter of the body blank D to its height H. H/D should be in the range of 3:1 - 5:1, and D itself should be 300-800 mm. If the diameter is smaller, the air, without having time to react with the fuel, will leave, taking the efficiency factor with it into the pipe, and if the diameter is too large, the fuel at the edges will burn too slowly, a hole will form in the center of the fuel mass, the pancake will sit in it and the stove will go out. But don’t rush to the barn to look for suitable hardware just yet! And don’t immediately reject the rusty fuel barrel; we’ll talk about it later.

The next most important parameter, especially for a boiler, is the thickness of the body wall Δ. If the stove has a water jacket and the body is made of ordinary steel, Δ should be within 4-6 mm. This condition requires special explanation.

Through too thin a wall, too much heat will immediately escape into the water; the exhaust gases will cool below 400 degrees immediately after leaving the gap between the “pancake” and the body, as shown in pos. A in Fig. left. Yes, the color of the wall does not correspond to its color temperature (steel heated to a yellow glow will melt), but to the heat flow through the wall in a given place.

As a result, the exhaust gases will not be able to burn out properly, the efficiency of the boiler will be unacceptable, dense carbon deposits will soon form on the walls of the combustion chamber, and abundant condensation will form in the chimney. The walls of the flame housing of the branded “Stropuva” are 2.5 mm thick, which is what many craftsmen take as a basis. But, firstly, it is made of heat-resistant steel, the thermal conductivity of which is much lower than that of conventional structural steel. Secondly, in Stropuv, residual gases are released from approximately 3/4 of the upper surface of the fuel mass and a small part of them is immediately in direct contact with the wall.

In the bubafon, the exhaust gases have to squeeze through a rather narrow gap, and their entire flow passes close to the wall. Therefore, a homemade bubafon boiler must be made with thick fire walls. Then the thermal resistance of a wall made of ordinary steel will be sufficient to maintain the required temperature in the afterburning space. The path of residual gases in this case is shown in pos. B fig. However, you can’t make the wall too thick either: the overall thermal/temporal inertia of the boiler will be such that the water in the system can boil even if the owner closes the air throttle or the automation works in a timely manner.

Is it possible from a leaf?

Of course, the housing shell can be obtained by rolling a steel sheet between rolls. But sheet bending machines amateurs and small “iron” individual entrepreneurs, as a rule, bend steel no thicker than 2.5 mm. Such a delicate bubafon is unlikely to be suitable for a boiler, but it is quite suitable for air-infrared heating of utility rooms. For more details, see below, about bubafon from a barrel.

Cylinder and pipe

Now you can mentally turn over your available metal resources: the best bubafonya is from an industrial gas cylinder or a piece of large diameter pipe. For power up to 12-15 kW, a cylinder is preferable - there is no need to cook the bottom, and the rounded top will ensure better afterburning. For oven low power this is especially important because the square-cube law is more fully reflected in it: the ratio of surface to volume increases with decreasing size of the geometric body. Typical main dimensions of balloon-tube bubafons are shown in Fig.

Air distributor

Now let's move on to the pancake. To optimize the work process in terms of efficiency, the gap between it and the housing should be 0.05D. For example, for a cylinder with internal D = 300 mm, the result is c = 15 mm. Then the diameter of the pancake d = D – 2H = 270 mm.

With ribs the situation is more complicated. Their height h depends on D nonlinearly. Within the limits of D = (600-800) mm, you can take h = 0.1D. For smaller D we calculate h as a proportion, knowing that for D = 600 mm h = 60 mm, and D = 300 mm h = 40 mm.

It remains to find the thickness of the pancake σ. The smaller D is, the larger it should be. Why? The weight of the pancake must be maintained within certain limits: bending too lightly will not press down the burning layer adequately, the efficiency will drop and the stove will be prone to flare-up and backburning. A pancake that is too heavy will simply press into the fuel and it will go out. A detailed calculation will take up too much space, and the value of σ is not very critical, so we’ll just indicate:

For D = 300 mm σ = 6-10 mm.
For D = 400 mm σ = 6-8 mm.
For D = 600 mm σ = 4-6 mm.
For D = 800 mm σ = 2.5-4 mm.

Intermediate values, if required, are calculated as a proportion and the larger of the standard range of sheet metal thicknesses is taken.

About the design of the air distributor

In a wood-burning boiler-boiler with a D of 500 mm, a pancake is usually installed, the design of which can already be called classic, on the right in the figure below. Ribs - straight sections of channel suitable size, located radially. Under the formed channels, the fuel will burn out faster, which will ensure the necessary drawdown of the pancake into its mass. The pancake itself can be made from a thinner sheet, 2-2.5 mm, which is easier to cut. And the necessary weight will be given to the oppression by a ring welded on top from the same channel. This design, by the way, is much less prone to jamming in large-diameter furnaces.

Please note that the mouth of the air duct is located along the lower edge of the ribs. This is necessary so that the air, before entering the combustion zone, warms up, passing several cm in the fuel mass. The small cone that forms in the center, if it grows too much, spreads out under the weight of the pancake. The stove makes a short creaking or grinding sound, this is normal.

For narrow, tall bubafons, the air path under a pancake with straight ribs turns out to be too short for good fuel combustion. Therefore, the ribs are curved clockwise when viewed from the side of the pancake. At the same time, their twisting creates a circulation (vortex) in the afterburner, which promotes complete afterburning in a small volume.

A physical-geographical curiosity: the vortex is formed due to the Coriolis force arising as a result of the rotation of the Earth. Therefore, in the southern hemisphere, if someone there intends to make bubafonya, the ribs should bend counterclockwise. Otherwise, instead of a vortex in the afterburner, a strong soot will settle on the walls.

In small bubafons (,), air must be supplied even deeper into the fuel and passed along a longer path before entering the combustion zone. But then you need to avoid the formation of too wide a cone of fuel under the center of the pancake. The optimal solution for a home-made worker is to weld an unusable star with a diameter of about 1/4-1/3 D at the mouth of the air duct, and with a central hole with a diameter of about 1/3 of the diameter of the air duct d, which we will still calculate, the average pos. in Fig.

But pancake on the left in Fig. – an example of complete disregard for technical common sense: thin, will burn out quickly. Cut through a tree stump, it will get stuck. Ribs from too high a corner: the stove will either flare up or not, but it still won’t heat properly.

Chimney

For further calculations, we will need the cross-sectional area of the chimney S. It is difficult to calculate it using known methods, because We do not know in advance the efficiency and other necessary parameters of a single product made from scrap materials. IN industrial conditions they make a prototype, “drive” it this way and that in the test chamber and, based on the data obtained, refine the initial ones for calculating the production model; Sometimes you have to make several prototypes.

Fortunately, considerable experience has already been accumulated in operating bubafons and making mistakes during their creation. Therefore, S can be derived with sufficient accuracy for an amateur from the specific hourly energy release of a fuel load e, without “bothering” with efficiency and duration of heat transfer. To do this, firstly, we set the maximum height of the fuel mass in the furnace Hf = 2/3H. Then, using school formulas, we determine the volume of fuel Vf. The specific heat of combustion of its different types is in reference books, but we need to know the mass. For some species, here are the calculation data:

Medium-sized aspen firewood: capacity (mass stacking coefficient) 0.143 kg per 1 cubic meter. dm. Vf; E = 2.82 kW/h.
Dry sawdust or small coniferous shavings: capacity 0.137 kg per 1 cubic meter. dm. Vf; E = 3.2 kW/h.
Alder briquettes: capacity 0.285 kg per 1 cubic meter. dm. Vf; E = 3.5 kW/h.
Hardwood briquettes: capacity 0.31 kg per 1 cubic meter. dm. Vf; E = 3.1 kW/h.
Hard coal WPC: capacity 0.4 kg per 1 cubic meter. dm. Vf; E = 4.85 kW/h.
The same, SSOM: capacity 0.403 kg per 1 cubic meter. dm. Vf; E = 5.59 kW/h.
Anthracite small AM: capacity 0.485 kg per 1 cubic meter. dm. Vf; E = 5.68 kW/h.
The same, large AKO: capacity 0.5 kg per 1 cubic meter. dm. Vf; E = 5.72 kW/h.
Belarusian peat: capacity 0.34 kg per 1 cubic meter. dm. Vf; E = 2.36 kW/h.

Now everything is very simple: we find the total hourly energy release E = eM, where M is the mass of the fuel load, then the minimum cross-section of the chimney S(sq. cm) = 1.75E(kW/h). For example, we have a cylinder stove. D = 3 dm, Hf = 6 dm. Vf = ((πD^2)/4)Hf = 42 cubic meters dm. We take the most energetic of the proposed fuels; let's say SSOM. It will fit in the firebox 42x0.403 = 17 kg, rounded up. This bookmark, if burned completely in an hour, can release E = 5.59x17 = 95.03 kW or, in round numbers, 100 kW. The cross-sectional area of the chimney required is S = 1.75x100 = 175 sq. cm, no less. Calculating back from area to diameter, we get 15 cm or 150 mm. A rhetorical question for experienced stove-makers: is such a pipe enough for 10 kW of heat? And anyone can calculate.

You can immediately estimate how much power the oven will produce. Homemade bubafoni give off heat for about 12 hours. Then Pstoves = 100/12 = 8.5 kW on good coal. And on sawdust? Let's divide their energy release (3.2 kW) by coal (5.59 kW), 3.2/5.59 = 0.572 and take the result as a correction factor k1 = 0.572. We define the second as the ratio of sawdust and coal capacities: k2 = 0.137x0.403 = 0.34; general correction k = k1k2 = 0.572x0.34 = 0.195. Using sawdust, the stove will produce 8.5 x 0.195 = 1.66 kW, this is enough to warm up a garage or poultry house 6 x 4 x 2.25 m to the operating temperature. To achieve “coal” power, sawdust will have to be burned in 0.195 x 12 = 2.34 or in about 2.5 hours. Is the stove capable of doing this at maximum? This technique does not answer this question. What can you do, it's approximate. But simple.

Here another question arises: a 20 kW “Stropuva” heats up for 5 days on a load of 140 kg of the same coal. What then is the efficiency of bubafoni on coal? And we won’t burn it at maximum, we’ll close the damper, otherwise the stove will burn out. Like “Stropuva”, if you remove its air regulator. To calculate it, it was necessary to reduce it to the same time, so 12 o’clock was taken as the characteristic time of combustion of firewood. This makes it more convenient to check against known experimental data.

Secondly, even in the most fanfare advertising brochures they write: “up to 5 days,” i.e. at a technical minimum power of 10% of the nominal. Total - 2 kW/h, and our stove with one load of 17 kg and releasing 2 kW/h will give off heat for 50 hours. And 140 kg, taking into account heat loss during ignition, will be enough for 4-5 days. The long-term efficiency is approximately the same as that of Stropuva, and without supercharging with a D/U switch.

About lighting coal

Typically, bubafonya is ignited by pouring a little flammable liquid into the air duct and throwing a match or a burning wick there. But you can’t light coal, especially anthracite, that way. To kindle coal, it is loaded along the bottom edge of the loading hatch, and dry small firewood is placed on top of the coal at 2/3 of the height of the opening, set on fire, and the door is closed.

When the wood burns down to glowing coals (branded boilers have a viewing window with heat-resistant glass for observation), the door is opened, coal is added to the top of the hatch and the air duct is completely opened. They watch the stove for half an hour; when it starts to heat up, cover the air duct until normal.

Air duct

The air duct based on the known cross-sectional area of the chimney is considered even simpler: d = (0.5-0.55)((4S/π)^0.5), designations are on the size diagram. And for our balloon stove with a chimney diameter of 150 mm, we will need a pipe 76-80 mm inside for the air duct.

For example, we bend the collar blank around the air duct pipe. It's not difficult, because... the collar can be made of galvanized steel. Having assembled or welded the joint, we put it on the pipe again, press it in one place and measure the resulting double gap. Let's say it comes out to 1.6 mm. Then δ = 0.8 mm; L = 64 mm and q = 214 mm. We take L = 65-70 mm and q = 215-220 mm. Do-it-yourselfers most often neglect the collar for the sake of simplicity, but in vain. The efficiency depends on it quite noticeably.

Other little things

The distance of technological openings from the top is i = h + σ + 20 mm.
The height of the bottom edge of the combustion door is Hm = Hf + h + σ + 30 mm, this is better for inspecting and cleaning the upper surface of the pancake.
Loading door height hm = H – Hf – i; We take the width of the door to be no more than 1/4 of the circumference of the flame housing along its outer diameter.
Ash pan door height ha = h + σ + (100-150) mm; width - same as for the loading door. A high ash pan door is necessary because... The coal in the bubafon may not burn out completely and you will have a hard time scooping out the baked remains.

Doors

For amateurs, a long-established technical method is also preferable: protruding necks and double doors with a gasket made of sheet asbestos or basalt cardboard, see fig. This design is also good because it protects to some extent from burns; the outer part of the door does not heat up to the outside temperature of the fire housing.

Water jacket

To ensure, if necessary, thermosyphon circulation of sufficient intensity, the layer of water in the jacket should be thinner, but not so thin that its own viscosity begins to affect. There is nothing to calculate here; in practice, the optimal value has long been worked out - 40-60 mm. The thickness of the metal is 1 mm per 1 bar of normal operating pressure for a jacket height of up to 2 m. In general, 2.5 mm steel will hold in any case, and it can be bent at home or in the home.

If we are talking about a bubafon-boiler, then the jacket must be perfectly concentric with the fire body and of uniform width, otherwise a cold spot will appear inside, disrupting the entire furnace mode. There are no serious difficulties here either: the upper and lower covers of the shirt are made from a corner bent into rings, as shown in Fig. right. It also shows that you first need to cut openings for the hatches in the fire housing, otherwise it will be very inconvenient later.

Where and how to put it?

The bubafonya stove gets very hot during operation, and the bottom of the boiler gets hot when the fuel burns out, this is the first thing. Second, because During the combustion process, pyrolysis also occurs; in the bubafon it is quite intense; the flue gases contain a significant amount of water, even if the fuel was loaded completely dry. As a result, the installation of bubafoni, in addition to the general fire safety requirements, should be made on a refractory base made of fireclay bricks, and the chimney should be equipped with a condensate collector with a drain valve, as shown in Fig. The bubafonya on legs must be placed in exactly the same way: the hot bottom radiates heat so strongly that cement screed the floor cracks and crumbles before your eyes, especially in damp rooms.

But still - from a barrel?

A bubafonya made from a barrel or thin sheet metal will definitely not fit under the boiler even with the most careful execution. The main thing is because the heat walls are too thin, as mentioned above. But for air heating utility rooms will do. In this case, to obtain acceptable quality indicators, the bending must be done according to the model of a pancake for “small-sized” bubafons, with curved blades and increasing their number. How exactly, look at the video below. Despite the relative complexity of the pancake, such a stove can be made by an average skilled craftsman in a day or two.

Video: bubafonya stove from a barrel

Where is bubafonya good?

The best option for using a bubafoni stove is air-radiant heating of small household or production premises , in which people or pets are constantly present during the cold season. Here the 12-hour operating cycle of the furnace is just right.

The second preferred option is backup stove in greenhouses and conservatories. The ideal stove for them runs only on wood. Suddenly they will not be there, but coal, peat, any flammable garbage will be available - the bubafonya will digest it and maintain the permissible temperature. Good for such a case homemade stove from a barrel: it will rarely have to be heated, and it will last a long time.

For heating at temporary work Bubafonya is not suitable for use in a garage or shed in winter: By the time it starts to burn, you need to leave, but you can’t until it burns out completely. It’s more profitable here: it heats up instantly, the heat transfer is regulated by a simple flood, when leaving urgently, you can fill the firebox with water or cover it with snow.

As for replacing branded heating boilers for residential buildings with bubafons, the problem that solves everything remains unresolved. Specifically, how to equip a movable air duct with thermomechanical automatic air supply control? Whoever guesses and does it will go down in the history of amateur technical creativity.

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