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The slow-burning heating stove “Bubafonya” is the creation of a craftsman from Kolyma (a resident of the Kolyma today, not Stalinist) Afanasy Bubyakin. He shared his successful experience on the network, where his nickname is bubafonja, which is why the stove got its nickname. For the prototype, Athanasius took the Lithuanian-made Stropuva boiler, which, no matter how they criticized it at times, has proven itself perfectly for almost 15 years of industrial production.

To date, bubafonya, one might say, is the favorite brainchild of amateur stove-makers. After Bubyakin's modifications, which will be discussed in more detail below, a home master of almost any qualification can do it with his own hands, as long as he knows how to handle a welding machine. You can “bundle up” bubafonya over the weekend, and for many the Kolyma stove is working properly and sheds almost for nothing (see fig.): bubafonya heats well on almost any solid fuel, from coniferous sawdust to anthracite.

Homemade stove “Bubafonya”

This gave rise to many attempts to adapt the bubafon for water heating at home: the price of a 20 kW Stropuva boiler exclusively wood-burning in the Russian Federation is currently about 90,000 rubles, and a universal firewood / coal is about 120,000 rubles. Analogues, which will be discussed later, cost 68-110 thousand rubles. Also not cheap.

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

• Fuel consumption corresponds to an efficiency of 60% at best.
• Carbon deposits are intensively formed on the walls of the fuel chamber.
• When the weather changes, you have to constantly run to the boiler room to manually adjust the air supply. You gape - the temperature of the coolant in the system for 15-20 minutes. jumps up to 95-97 degrees, and this is already on the verge of boiling with all the consequences.
• The heat transfer time from one load of fuel is up to 12 hours versus 30 or more for Stropuva.
• Water condensate in the chimney is formed so abundantly that in severe frost it freezes and blocks the chimney.
• There are cases of "backburning" when the stove draws air through the chimney, and flames beat out of the duct.

In general, a bubafon with a water circuit works more or less reliably and stably only when up to 10-15% of its thermal power is taken 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. She needs an internal supply of heat in order to properly burn the exhaust gases (a mixture of pyrolysis and flue gases).

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

The end result is ambiguous. On the one hand, the Bubafonya boiler is still a possible thing. On the other hand, you still need to think and think, try and think again. Especially - with automation and a firewood / coal switch. But we're getting ahead of ourselves, to the point.

Prototype

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

The scheme of the Stropuva boiler is shown in fig. left below. It has several differences from the then existing (2001) design of furnaces and surface combustion boilers. The first is air preheating chamber 2. It is supplied to the fuel heated to about 400 degrees, which ensures combustion together with pyrolysis and efficient 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 the following figure on the right). The distributor is a crosspiece of complex configuration 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 fed 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 area above and below the air distributor. Slightly higher, already burned out, but still very hot flue gases swirl; their heat can be used in any way without disturbing the thermochemical cycle of the firebox. In essence, "Stropuva" is a 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 the air supply is left at maximum, the fuel flares up. 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 2 of its schemes are used: on bimetallic plates and lever-differential.

About thermomechanics

The principle of operation of thermomechanics on a bimetal (thermal springs) is based on the difference in thermal expansion coefficients (TEC) of various materials, see fig. The smaller the initial angle of divergence of the plates α, the greater the bending of the spring with the same heating. Therefore, thermal springs are most often made from plates sintered over the entire plane by resistance welding, a bimetallic plate is obtained. With a small, less than 100 degrees, heating, it literally bends in an arc with great force.

Thermal springs (thermobimetallic plates) do not require complex damper drive kinematics; 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 high internal stresses, quickly get tired: you have to adjust the temperature in the system using a thermometer about once a month, and every season or two the spring (plate) needs to be changed, it bends for good.

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

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

Plates for a home-made thermal spring should be taken 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 about the same amount of beryllium bronze, 1 mm of ordinary tin bronze and 2 mm of brass.

Sometimes in factory boilers, thermomechanics is made differential-lever. 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 tracked by a pair of long-armed levers hinged at one point. The lever-differential system is durable and stable, but requires quite complex kinematics of precision precision parts, because linear difference in the expansion of the shells of the boiler fractions of a millimeter.

Returning to Stropuva, ​​it remains to talk about the firewood / coal switch and the features of the boiler piping. Initially, the Lithuanian boiler was designed for oil shale, which the Baltics are rich in. Slate burns approximately like a tree, so Stropuva went under the firewood without significant alterations.

But there were problems with coal: additional air is needed to burn off its off-gases. It was taken from the air heater, arranging a manually controlled valve in it, but the rarefaction in the afterburning space was not enough for the necessary suction. It turned out to be impossible to solve the problem just like that; for a coal-fired furnace, it was necessary to make a pressurization from an electric fan at the rate of approximately 1 W of electric for pressurization per 1 kW of boiler heat transfer. However, for manufacturers, this is a blessing in disguise: a blower fan is not included in the universal boiler kit, it is optional. For a fee.

That is, the coal "Stropuva" has lost its energy independence, this must be remembered when planning a purchase or trying to repeat the design. And loading from some grades of coal at the same time 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 is separated from the ash.

At Stropuva coal, it provides heat transfer for up to 5 days. To date, this indicator is very average: coal-fired boilers of ultra-long burning at one load heat up to 30 days and allow you to add fuel without stopping and disturbing the combustion regime, i.e. They need ignition once a season. But they work only and only on coal.

strapping

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

The first thing that attracts attention is a 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, in the stairwell. Balancing valve bk1 in cold weather (at the maximum boiler) is adjusted so that the radiator is slightly warm.

The temperature (not thermal!) inertia of the boiler is 20 degrees, and the time is about 20 minutes. That is, if 70 degrees are set on the boiler according to the standard thermometer, then the coolant temperature can vary from 60 to 80 degrees within 20 minutes. At this time, the excess coolant is bypassed to R1, which thus plays the role of an emergency radiator, but without disturbing the combustion regime and reducing the boiler efficiency.

The second heat buffer is DHW boiler B; it is strongly not recommended to operate the boiler without it. The bypass valve 3 sets the temperature of the DHW water, and the same lower according to the scheme - the temperature of the general-purpose registers.

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

The second balancing valve bk3 is paired with a 40-80 W circulation pump P, providing an optimal circulation rate in the boiler jacket and registers separately. If the pump is with automatic speed control according to the supply temperature, then bk3 is not needed, therefore it is optional.

Such a scheme does not require regular replenishment from the water supply, and drain 5 is used only when re-feeding, 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 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.

Is Stropuva good?

To the above disadvantages, of which the main one is slow heating (20 minutes for the boiler itself, and the whole system?), The following must be added:

1. The impossibility of technological shutdown: the fuel load must burn out completely, only then can some work be done on the boiler and the system.
2. The impossibility of reloading fuel without re-ignition.
3. 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 by real users, 76-78%
4. Under the boiler, you definitely need a separate boiler room according to the requirements of the Ministry of Emergencies (from 8 cubic meters, a ceiling from 2.2 m, made of non-combustible materials, an openable window, an unobstructed supply window for air, a separate smoke channel).

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

• Exceptionally high reliability of the boiler, incorporated 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 malfunctions are easily eliminated, do not cause the boiler to stop and make themselves felt in advance.
• In the event of a power outage, the boiler automatically switches to thermosiphon circulation without any outside interference and can operate in this mode for an unlimited time with a regular fuel load. It will be cold in the house, but the system will not defrost.
• Easy and inexpensive binding.
• The piping scheme, if an indirectly heated hot water boiler (with a built-in heat exchanger) is installed, allows you to fill the system with antifreeze without re-feeding for 5-7 years or more.
• The installation of the boiler does not require a refractory base or reinforcement of the flooring, as long as it is fireproof.
• Large power adjustment limit, more than 10 times.
• The real efficiency is kept within the power adjustment limit of 100-10%.
• As a consequence of the 5 previous points, the economy in terms of money both during commissioning and during it.

Analogues "Stropuva"

Although today "Stropuva" is far from the last word in heat engineering, in terms of TTD, performance and environmental requirements, the boiler remains at the level of modern requirements, and its design has been worked out and time-tested. It is not surprising that, using Lithuanian licenses, many companies produce Stropuva analogues 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 of Lithuanian licenses do not take, difficulties in obtaining. But instead, on the Russian market there is a line of KVR boilers (Tverdotop trademark, see the figure on the right) of the Medved concern, which are inferior to Stropuva in the accumulated operating time, but in some ways they are superior to the Lithuanian:

1. The price is 20-25% lower with comparable technical data. For a 20 kW wood-burning boiler, 68 thousand versus 85.
2. 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. "Lithuanian" needs to be drowned with chocks.
3. Loading door 940 mm high; the whole stack of firewood is immediately in front of your eyes, you can fix it below without touching the top.
4. The air distributor lifting mechanism is combined with the door and assembled on rollers. In "Stropuva" the lifting cable is stretched in the tube: it is harder to pull, and the tube is rubbed over time.
5. Fool-proof ash pan door, which negates the fire hazard.
6. Doors do not burn, and their seals are hard to wear.
7. There is a damper on the chimney, i.e. the boiler can be connected to any existing excess draft pipe.
8. The allowable pressure in the system is 2.5 bar, which allows heating 2 floors with an attic within the limits of sanitary standards.

At the same time, "Tverdotop - Bear" is not without noticeable shortcomings:

• The minimum ceiling height of the boiler room 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 hit an opening in the wall under the pipe, which is easier than in a concrete floor, then you will still need to increase the height of the boiler room and put an extra knee that needs to be cleaned.

In general, the KVR with the Stropuva cannot be called enemies, both are designed for their own operating conditions. "Stropuva" - in places more or less inhabited with developed standard construction and with a climate closer to European. CWR will be more effective in conditions of a sharply continental climate in the regions where more are built on their own.

"Slow boiler" or pyrolysis?

It turns out that pyrolysis in slow-burning boilers barely peeps somewhere in the area of ​​\u200b\u200bthe air deflector? And this affects its quality indicators? Yes, and purely with separate gasification and combustion, it surpasses slow-burning boilers in the following parameters:

1. High efficiency; 95% is the norm.
2. Stable operation on any type of fuel: two-stage combustion with feedback is a fundamentally stable process.
3. Compactness: a 20 kW boiler is the size of a washing machine, it can be placed simply in the kitchen, if only the firefighters allow it.
4. Environmental friendliness: only CO2 and H2O are emitted, which in principle allows firefighters to issue permits for operation without a separate boiler room.

But the ubiquitous distribution of "pyrolyzers" is also hampered by serious shortcomings:

• High cost, about twice as high as that of a "slow" boiler for the same power.
• Small limits of power adjustment: superiority in efficiency in real conditions during changing weather is often radiated into the world space by an emergency radiator and leaks into the sewer by dumping overheated coolant.
• Limited service life of the heat-resistant lining of the combustion chamber, i.e. requires regular costly repairs.
• Complete energy dependence: without fan pressurization and power supply to the control automation, the boiler simply goes out.

In general, the pyrolysis boiler is only a good prospect so far. He will say his word when the developers cope with his shortcomings, and the increased price of fuel will make him count the percentage of efficiency.

We take on Bubafonya

Now let's find out why the bubafon oven is so popular. What was Bubyakin's contribution to the original design that made it repeatable by the simplest means at home while maintaining parameters comparable to branded ones?

But then there is no way to attach an air heater, and heating of the incoming air is necessary, otherwise do not expect a decent efficiency. In the Kolyma Territory, this is by no means an abstract question.

Bubyakin also solved this problem in the spirit of the whole furnace: he replaced the complex air distributor-deflector with a rather heavy oppression-"pancake" with ribs from below. Thus, 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 as it should, literally centimeters from the mouth of the duct. This made it possible, with the correct design of the furnace and its proper operation, to avoid backburning, at the same time reducing the height of the furnace by almost half and maintaining in such an extremely simple design (see the figure on the right) an efficiency of over 70% The thermal power is regulated, as in Stropuva , air supply.

The exit of exhaust gases for afterburning was also provided in an elementary simple way: into the gap between the "pancake" and the wall of the furnace. The share of pyrolysis in the zone under the pancake in the Bubyakin furnace increased; the role of afterburning in the space above the yoke also increased accordingly. This and some other circumstances, see below, explain the difficulty of adapting bubafoni to a heating boiler.

Curious fact

Shortly after the description of bubafoni appeared in RuNet, Stropuva announced an important improvement: a new design air diffuser, see fig. on the left, allowing you to add a few percentage points to the efficiency. Interestingly, did they even write about this to Athanasius himself in Kolyma?

Where can I get blueprints?

In free sources, accurate information about the correct proportions of bubafoni is not found, and paid sources completely bypass this topic. It is understandable, this stove is made mainly from improvised trash, as anyone understands and can. The limiting parameters that the idea itself is capable of giving here, of course, are not to be expected.

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

Among Murphy's laws, which, after Murphy himself, was accumulated in a rather plump pamphlet, there is this one: "Any simplicity is only the visible part of the hidden complexity." But do not be embarrassed, now we will explain everything to you in such a way that the construction of the stove takes 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 within 3:1 - 5:1, and D itself should be 300-800 mm. With a smaller diameter, the air, not having time to react with the fuel, will leave, taking it with it into the efficiency pipe, and if it is too large, the fuel will burn too slowly at the edges, a hole will form in the center of the fuel mass, the pancake will sit in it and the stove will go out. But do not rush to the barn to look for a suitable piece of iron! And do not immediately reject a rusty fuel barrel, we will talk about it later.

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

Too much heat will immediately go into the water through a too thin wall, the exhaust gases will cool below 400 degrees immediately after leaving the gap between the “pancake” and the body, as shown in pos. A of 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 flow of heat through the wall in a given place.

In total, the exhaust gases will not be able to burn out properly, the efficiency of the boiler will turn out to be unacceptable, dense deposits will soon form on the walls of the combustion chamber, and abundant condensate will form in the chimney. The walls of the fire chamber 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 "Stropuw" residual gases are emitted from about 3/4 of the upper surface of the fuel mass and immediately a small part of them directly contacts the wall.

In the bubafon, the exhaust gases have to squeeze through a rather narrow slot, and their entire flow passes close to the wall. Therefore, a home-made bubafon boiler must be made with thick flame walls. Then the thermal resistance of the wall of ordinary steel will be sufficient to maintain the required temperature in the afterburning space. The course of the residual gases in this case is shown in pos. B fig. However, it is also impossible to make the wall too thick: the general thermal / temporal inertia of the boiler will turn out to 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 sheet?

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

Cylinder and pipe

Now you can mentally turn over the available metal resources: the best bubafonya - from a gas cylinder for industrial use or a piece of large diameter pipe. For power up to 12-15 kW, the cylinder is preferable - the bottom does not need to be cooked, and the rounded top will provide better afterburning. For a low-power furnace, this is especially important, because. the square-cube law will more fully affect it: the ratio of surface to volume increases with a decrease in the size of a geometric body. Typical main dimensions of balloon-pipe bubafons are shown in fig.

Air distributor

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

With ribs, the situation is more complicated. Their height h depends on D non-linearly. Within 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 pancake thickness σ. It should be the larger, the smaller D. Why? The weight of the pancake must be kept within certain limits: oppression that is too light will not press down the burning layer in moderation, the efficiency will drop and the stove will be prone to flashing and backburning. Too heavy a pancake will simply be pressed into the fuel and it will go out. A detailed calculation will take too much space, and the value of σ is not very critical, so we simply 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 taken from the larger standard range of sheet metal thicknesses.

About the design of the air distributor

In a wood-burning bubafon boiler with a D of 500 mm or more, they usually put a pancake, the design of which can already be called classical, on the right in the figure below. Ribs - straight sections of a channel of a 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, it 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 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 a few cm in the mass of fuel. The small cone formed at the same time in the center, if it grows too much, spreads under the weight of the pancake. At the same time, the stove makes a short creaking or grinding sound, this is normal.

For narrow high bubafons, the air path under the straight-finned pancake is too short for good combustion of the fuel. Therefore, the ribs are curved clockwise when viewed from the side of the pancake. At the same time, their swirling creates circulation (vortex) in the afterburner, which contributes to complete afterburning in a small volume.

Physical-geographical curiosity: the vortex is formed due to the Coriolis force arising from the rotation of the Earth. Therefore, in the southern hemisphere, if someone there intends to make a bubafon, the ribs must be bent counterclockwise. Otherwise, instead of a vortex in the afterburner, a strong soot will sit on the walls.

In small bubafons ( , ), air must be fed even deeper into the fuel and passed before entering the combustion zone along a longer path. But then you need to avoid the formation of too wide a cone of fuel under the center of the pancake. The best way out for a do-it-yourselfer is to weld a worthless sprocket with a diameter of about 1/4-1/3 D at the mouth of the duct, and with a central hole with a diameter of about 1/3 of the diameter of the 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, burns out quickly. Cut through a stump-deck, it will get stuck. Ribs from a too high corner: the stove will either flare up, or it won’t flare up, but it still won’t heat up properly.

Chimney

For further calculations, we 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 improvised materials. In industrial conditions, they make a prototype, “drive” it this way and that in the test chamber, and according to the data obtained, they refine the initial ones for calculating the serial sample; sometimes you have to make several prototypes.

Fortunately, a lot of experience has already been accumulated in the operation of bubafon and errors in their creation. Therefore, S can be derived with sufficient accuracy for an amateur from the specific hourly energy release of the fuel load e, without "bothering" the 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, according to school formulas, we determine the volume of fuel Vf. The specific heat of combustion of its various types is in reference books, but we need to know the mass. For some species, here is the data for calculation:

• Aspen firewood of medium size: capacity (mass stacking factor) 0.143 kg per 1 cu. dm. vf; E = 2.82 kWh.
• Dry sawdust or small shavings of coniferous: capacity 0.137 kg per 1 cu. dm. vf; E = 3.2 kWh.
• Alder briquettes: capacity 0.285 kg per 1 cu. dm. vf; E = 3.5 kWh.
• Hardwood briquettes: capacity 0.31 kg per 1 cu. dm. vf; E = 3.1 kWh.
• Hard coal WPC: capacity 0.4 kg per 1 cu. dm. vf; E = 4.85 kWh.
• The same, SSOM: capacity 0.403 kg per 1 cu. dm. vf; E = 5.59 kWh.
• Small anthracite AM: capacity 0.485 kg per 1 cu. dm. vf; E = 5.68 kWh.
• The same, large AKO: capacity 0.5 kg per 1 cu. dm. vf; E = 5.72 kWh.
• Belarusian peat: capacity 0.34 kg per 1 cu. dm. vf; E = 2.36 kWh.

Now everything is very simple: we find the total hourly energy release E \u003d eM, where M is the mass of the fuel load, then the minimum cross-section of the chimney S (sq. cm) \u003d 1.75 E (kW / h). For example, we have a cylinder stove. D = 3 dm, Hf = 6 dm. Vf = ((πD^2)/4)Hf = 42 cu. dm. We take the most energetic of the proposed fuels; Let's say SSOM. It will fit in the firebox 42x0.403 = 17 kg, with rounding. The energy of this bookmark, if it is burned completely in an hour, is able to allocate E \u003d 5.59x17 \u003d 95.03 kW, or, rounded, 100 kW. The cross-sectional area of ​​​​the chimney is needed S \u003d 1.75x100 \u003d 175 square meters. see 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? Anyone can calculate.

Here you can estimate how much power the furnace will get. Homemade bubafoni give off heat for about 12 hours. Then Pfurnace = 100/12 = 8.5 kW at a good angle. What about 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. The second is defined as the ratio of sawdust and coal capacities: k2 = 0.137x0.403 = 0.34; total correction k = k1k2 = 0.572x0.34 = 0.195. On sawdust, the stove will give out 8.5x0.195 \u003d 1.66 kW, this is enough to warm up the garage or poultry house 6x4x2.25 m to the temperature for ensuring activity. To achieve "coal" power, sawdust will have to be burned for 0.195x12 \u003d 2.34 or in about 2.5 hours. Is the stove capable of doing this at maximum? This method does not provide an answer to this question. What can you do, it is approximate. But simple.

Here another question arises: 20-kW Stropuva heats up for 5 days at a load of 140 kg of the same coal. What then is the efficiency of bubafoni on coal? And we will not burn it at the maximum, we will cover the damper, otherwise the stove will burn out. As well as "Stropuva", if you remove the air regulator from it. For the calculation, it was necessary to reduce to the same time, so 12 hours are taken as the characteristic time for the combustion of firewood. So it is 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 last for 4-5 days. Long-term efficiency is about the same as that of Stropuva, ​​and without boost with a D / U switch.

About kindling coal

Usually bubafonya is kindled by pouring a little flammable liquid into the duct and throwing a match or a burning wick into it. But coal, especially anthracite, cannot be kindled like that. To kindle coal, it is loaded along the lower edge of the loading hatch, and dry small firewood is placed on top of the coal at 2/3 of the opening height, set on fire, and the door is closed.

When the firewood burns out to blazing coals (in branded boilers for observation, a viewing window with heat-resistant glass is provided), the door is opened, the coal is loaded to the top of the hatch and the air duct is completely opened. Half an hour or an hour they watch the stove; when it starts to heat up, cover the air duct to normal.

air duct

The air duct according to the known cross-sectional area of ​​\u200b\u200bthe chimney is considered even simpler: d \u003d (0.5-0.55) ((4S / π) ^ 0.5), the symbols are on the size diagram. And for our balloon stove with a chimney diameter of 150 mm, you will need a pipe 76-80 mm inside for the air duct.

For example, we bend the collar blank around the duct pipe. This is 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 1.6 mm came out. Then δ = 0.8 mm; L = 64 mm and q = 214 mm. We take L = 65-70 mm and q = 215-220 mm. Homemade collars are most often neglected for the sake of simplicity, but in vain. The efficiency depends on it very noticeably.

Other little things

• Indentation of technological openings from the top i = h + σ + 20 mm.
• The height of the lower edge of the furnace door Hm = Hf + h + σ + 30 mm, so it is better for revision and cleaning the upper surface of the pancake.
• Loading door height hm = H – Hf – i; we take the width of the door no more than 1/4 of the circumference of the flame body along its outer diameter.
• Ash pan door height ha = h + σ + (100-150) mm; width - 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 be tormented to rake out the caked residues.

doors

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

Water jacket

To ensure, if necessary, thermosiphon circulation of sufficient intensity, the water layer in the jacket must be thinner, but not so much that its own viscosity begins to affect. There is nothing to consider 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 with a shirt height of up to 2 m. In general, 2.5 mm steel will hold in any case, and you can bend it at home or at home.

If we are talking about a bubafon-cauldron, then the jacket must be ideally concentric to the flame body and of uniform width, otherwise a cold spot will appear inside, knocking down the entire oven mode. There are no serious difficulties here either: the top and bottom covers of the shirt are made from a corner bent into rings, as shown in fig. on right. It can also be seen there that first you need to cut openings for hatches in the fire chamber, otherwise it will be very inconvenient later.

Where and how to put?

The bubafon furnace heats up very much during operation, and the bottom of the boiler heats up when the fuel burns out, this is the first. Second, because during the combustion process, pyrolysis also occurs, in bubafon it is quite intense, the composition of the flue gases includes 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 protection requirements, must be carried out on a refractory base made of fireclay bricks, and the chimney must be equipped with a condensate collector with a drain cock, as shown in fig. Bubafonya on legs should be placed in exactly the same way: the hot bottom radiates heat so strongly that the cement floor screed cracks and crumbles before our eyes, especially in wet rooms.

And yet - from the barrel?

Bubafonya from a barrel or thin sheet metal under the boiler will not go unambiguously with the most careful execution. The main thing is because of too thin flame walls, as mentioned above. But for air heating of utility rooms it will do. In this case, in order to obtain acceptable quality indicators, oppression must be performed according to the model of a pancake for bubafon - “small sizes”, with curved blades and increasing their number. How exactly, look at the video below. Such a stove, despite the relative complexity of the pancake, can be made by a skilled craftsman in a day or two.

Video: barrel oven

Where is bubafonya good for?

The best option for using a bubafoni oven is air-radiant heating of small utility or industrial premises in which people or pets are constantly in the cold season. Here the 12-hour duty cycle of the oven is just right.

The second preferred option is backup oven in greenhouses and conservatories. The ideal oven for them works only on wood. Suddenly they will not be there, but coal, peat, any combustible garbage will be available - bubafonya will digest it and maintain an acceptable temperature. For such a case, a home-made stove from a barrel is well suited: it will rarely have to be heated, and it will last a long time.

Bubafonya is not suitable for heating during temporary work in winter in a garage or barn: until it flares up, you need to leave already, but you can’t, until it burns out completely. It’s more profitable here: it heats up instantly, heat transfer is regulated by a simple fire, leaving urgently, you can fill the firebox with water or throw snow.

As for the replacement of branded heating boilers for residential buildings with bubafons, there remains an unresolved problem that solves everything. And 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.

You can upgrade your device as follows:

1. For a water jacket, you will need two metal sheets 3 mm thick. They must be bent and connected into a closed metal casing by welding.
2. The Bubafoni fuel tank is placed inside the hull.
3. Pipes are connected through which air and water will be supplied.
4. The last step is to install the appropriate size cover.

The heating furnace, combined with a water heating system, is ready for operation.

Fuel types

The long-burning furnace "Bubafonya" can work with the same efficiency on any combustible substance. But still there are some differences: the duration of autonomous operation and the efficiency of the boiler depend on the type of raw material.

The following materials are suitable as fuel:

1. Coal. It provides battery life for 50-60 hours. The disadvantage of this type of fuel is that during operation a significant amount of soot is formed, which requires constant cleaning of the furnace and chimney.
2. Sawdust. A fairly common type of raw material, but it will be necessary to add 30% wood and provide good traction.
3. The most suitable type of raw material remains firewood. They almost do not form soot, during smoldering they emit a lot of gases. The only condition is that dry wood must be used.

Conclusion

As a conclusion of the article, I would like to summarize:

1. To create a design, any cylindrical container is suitable. The main thing is that the walls are strong and steel.
2. The construction of a water jacket allows you to connect a water heating system.
3. It is necessary to make an oven in the open air.
4. When designing a chimney, it should be possible to dismantle and replace it, since this part of the structure is often clogged.
5. It is forbidden to cover metal parts with varnish and enamel. It is preferable to use heat-resistant paint.
6. It is recommended to use firewood that is suitable for the size of the firebox.
7. When working with the stove and while laying fuel, gloves should be worn to protect against burns.
8. It is forbidden to place flammable objects near the stove: paper, rags, furniture.
9. It is not allowed to burn plastic and other household waste in the oven.
10. It is required to exclude the use of combustible substances for ignition.
11. It is recommended to start using the heater for cooking no earlier than 15 minutes after lighting it up.

At the beginning of the 20th century, people invented potbelly stoves. They were indispensable helpers in winter in various conditions. However, they spent a lot of firewood, which quickly burned out. Therefore, in the future, another design was invented, it is now popularly referred to as "Bubafonya" - a long-burning stove. It can give off heat much longer than ordinary potbelly stoves, because the fuel in it burns out gradually.

What is the difference between the combustion process of an ordinary potbelly stove and "Bubafoni"

In potbelly stoves, fuel (firewood) burns very hot and fast. For this reason, its efficiency is low. The fire had to be contained. It was decided to compress all the laid firewood so that they do not burn, but smolder. In fact, this is the same potbelly stove, but only with a fuel press. And the name "Bubafonya" came from the name of the person who posted information and drawings of the furnace design to the World Wide Web. Since then, this model has become very popular and widely used.

What you need to make "Bubafoni"

Here is a drawing of the Bubafonya furnace, according to which it is easy to understand the elements of its design. It is made simply, the main thing is to have a welding machine and find the necessary materials. The ideal material is an old gas cylinder. However, it can also be made from a barrel or pipes whose diameter is large enough for the Bubafoni case. We will also need tools:

• welding machine and everything for welding;
• Bulgarian or;
• gas cylinder or metal barrel;
• metal pipes with a diameter of 10 cm.

Material for manufacturing

The ideal Bubafonya stove from a gas cylinder is the most suitable material, and besides, it is easy to find. All actions with it must be performed in the order that will be described now. The safety of the master, who will do all the work, depends on this.

The first step is to turn off the valve. This will allow any remaining gas that may have remained inside to escape. Then, through the hole, you need to pour water into the internal cavity of the cylinder. This will allow you to be sure that in the process of cutting it, nothing will ignite or explode.

Further, making the Bubafonya stove with their own hands, they build a press that will put pressure on the fuel, preventing it from flaring up. It is made from sheet steel, cutting out a circle that should easily pass inside the cylinder. A hole with a radius of 10 cm is made in its center. After that, a pipe with a diameter of 10 cm is welded to it, and a length slightly higher than the cylinder. This internal structure is heavy enough to compress the fuel, and the chimney will ensure that the minimum amount of air is passed through to sustain the combustion. Thus, the wood inside is rather slowly smoldering than burning. Because of this principle of action, "Bubafonya" - - got its name. After all, it is really capable of giving heat from 6 to 20 hours from one tab.

After that, a hole is cut in the middle of the cut-off hemisphere of the cylinder; a pipe should fit tightly into it, which ensures the flow of air to the fuel. After that, we can assume that the Bubafonya itself is done. Now you need to weld the chimney. To do this, a hole with a radius of 10 to 15 cm is cut out in the wall of the cylinder, under the lid itself. After that, they take a pipe of the same diameter and create a knee - this will be a chimney. It is welded to the hole. In principle, everything, the simplest Bubafonya furnace, the reviews of which are so positive, has been done, you can try to flood it.

We drown "Bubafonya"

To kindle the stove, you need to lay firewood inside the cylinder and let it flare up a little. When they are engaged, the inside of the stove is installed on top of them, which will press. Then a cover from the upper hemisphere of the cylinder is put on the outlet pipe. Handles can be welded on it for ease of use. The smoke that is released from combustion fills the cavity of the cylinder above the metal pancake, which is a press, and the top cover, after which it goes into the chimney.

Important little things

To prevent combustion products from escaping into the room, the lid and the top of the cylinder must be well sanded for better contact. You should also make a hole in the lid with high quality, into which the pipe for supplying air to the furnace passes. If the master takes into account all these design nuances, then the “Bubafonya” (long-burning stove) will heat the room well, and there will be no debris and smoke smell from it.

Any type of waste wood lumber can be loaded into such an oven. Sometimes you have to make the press heavier by welding pieces of metal onto it. How much to increase the weight, during operation it will become clear.

Options for improving the pyrolysis oven

When the "Bubafonya" burns, or, more precisely, smolders, the body is very hot. This is inconvenient in the sense that standing near her is too hot. The way out is to create a shirt around the body, which can be made from ordinary tin. They take a piece of galvanized steel, which is as tall as Bubafonya itself, . And they make a pipe out of it so that it is 5-10 cm wider than the stove itself. It turns out that the “Bubafonya” (long-burning stove) is red-hot, and gives off its heat to the internal space between it and the shirt, from which the latter also warms up, but significantly less. This allows you to feel comfortable near the hearth, without fear of getting burned. The place where Bubafonya will be located also needs to be protected from its high temperature. It is necessary to put refractory bricks under it or cast such a pedestal for the furnace from heat-resistant materials.

All these improvements will ensure not only the convenience of using the unit, but also prevent the risks associated with fire safety.

Stove "Bubafonya" with a water jacket, which will allow you to heat the whole house

The stove can heat water with the heat of its body, which can be let into the heating system of a private house. To do this, make a water jacket around the body. It is a metal box, or barrel, in which the entire body of the furnace is placed and filled with water. When the "Bubafonya" is hot, its temperature heats the water, and it can already be transmitted through the heating system. Thus, the Bubafonya stove, created with your own hands, can act as a boiler that heats the house. When creating a shirt, it is very important to weld it well to avoid leakage. The wall thickness should not be less than 3 mm. Also, if "Bubafonya" fits completely into a shirt, you will need to make another cover that would cover the entire structure.

Another option for creating a water jacket is shown in the photo. It can be seen from it that a compact heat exchanger is located around the Bubafoni case. It heats water and delivers it through pipes to batteries. As you can see, the design takes up very little space.

In this article, we have fully studied the topic of how to make a stove. "Bubafonya" at home is built from materials that most people throw away or scrap. We also learned various modifications of the device.

Rules for the safe use of "Bubaphoney"

• Do not place flammable objects near the stove: paper, plastic, furniture.
• It is better to wear construction gloves to load fuel.
• Do not use flammable liquids to light the stove. But in the case when the fuel does not ignite, it is worth moistening individual pieces of wood with combustible material. After that, put it in the firebox with the others and only then gently set it on fire.
• If you need to cook food on the Bubafon, you should do this only when it is fully warmed up.
• Do not touch any part of the oven to avoid burns. If, for any reason, this must be done, then it is worth wearing thick heat-protective gloves. After all, as described above, the body of the bubafoni is very hot.
• To turn off the stove, you need to close the damper on the pipe through which air is supplied to the furnace. After that, it will turn itself off after a certain time.
• In order for the stove to work for a very long time, you should not burn plastics or polyethylene in it. Firstly, these materials emit toxic gases, and secondly, they leave carbon deposits in the system, which are very difficult to remove.
• It must be remembered that resinous wood species often form condensate on the working surfaces of the stove, this can interfere with combustion.
• Do not paint parts of Bubafoni, because when it is heated, the paint can release toxins.
• The oven must be installed on a non-combustible substrate.

Afterword

There are many improvements, but the scheme of work is the same, as shown by the drawing of the Bubafonya furnace, located at the beginning of this article. Therefore, regardless of which option the reader chooses for himself, you should always adhere to the rules set forth here. This will allow you to safely heat the room, and the unit itself will serve its owner for a long time and regularly.

This publication will discuss the prototype 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 for an uninformed reader, but meanwhile the popularity of this stove is very high. This is also explained by the fact that the scheme of its device is quite simple, and the bubafonya itself can be attributed to long-burning furnaces that consume fuel economically and do not require its constant addition to the furnace.

Heating in a personal household is required not only for living quarters. Many owners cannot imagine a single day without working, for example, in a workshop or garage, and in winter it will be very uncomfortable in these buildings without local heating. Heating may also be necessary in home gardens - greenhouses, rooms for pets and poultry.

It is extremely difficult and ruinous to conduct a heating circuit from the house into such buildings. It is better to provide for the installation of stoves that can be heated as needed with solid fuel - wood, sawdust, coal, etc. There are many such options, and many of them are both economical and easy to use. Stoves can be purchased in stores, but a good owner can always make it on his own. One of these common crafts - do-it-yourself bubafonya oven.

Basic principles bubafonya oven work

The name " bubafonya"Comes from the network nickname" bubafonja", Which belongs to the Russian master Afanasy Bubyakin from the distant Kolyma. It is not known whether he was the first to create a home-made stove of a similar design, but it was his model, the assembly experience of which he shared on the Internet, that became a kind of “hit”, a basis for imitation, a base for his own developments and improvements for many home craftsmen.

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

Stropuva boilers are produced in a fairly wide range of models, from S7 to S40 (the figure 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 both ignites and burns from top to bottom. This is achieved by the fact that the air necessary for the oxidation process is supplied only to the thin upper layer of the load.

The diagram shows a schematic diagram of the Strоpuva boiler.

• The combustion chamber (8) is loaded with solid fuel (wood, sawdust, coal, briquettes) through a special window (6).
• Ignition of the upper layer is usually carried out using flammable liquids. The air distribution device (7) is then lowered onto this layer. It can have a cruciform shape with special deflectors for supplying 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 Strоpuva designers from Bubafoni, since such an innovation was made after the publication of its scheme.

• In order for the furnace to work stably, the supplied air needs some preparation - heating to about 400 ºС. This process takes place in a special chamber (2). In the same chamber, a special mode switch is installed - 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 moves forward as the combustion zone lowers.

• The intensity of combustion 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, which changes its configuration depending on the heating temperature
• Since " Strоpuva"It is designed specifically for the heating system, a heat exchanger (water jacket) is provided with pipes for the return (11) and the outlet of heated water (10).
• A hatch (9) is mounted in the lower part of the body for revision and cleaning of the boiler from residual combustion products.

The combustion of the upper layer of fuel with a dosed intake 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 that, the exhaust gases are discharged into the chimney opening (3).

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

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

Approximate diagram of the device of the bubafoni stove

• A very complex air distributor was replaced by a massive disk - a "pancake", from the bottom of which deflectors from a metal profile - a channel or a corner are welded. 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 gradually descends as the fuel is consumed.
• Now about the duct. It was made not 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 descends - 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 "suction" of air from the outside.

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

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

In the upper part of the body, an outlet pipe is welded for the outlet of combustion products, which is connected to the chimney.

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

Prices for a linear range of heating boilers Stropuva

Heating boilers Stropuva

Do-it-yourself bubafonya oven - we calculate the main parameters

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

If it was not possible to 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. Dimensions of the stove, that is, the body diameter (D) and its height (H) must be in a certain proportion. The optimal ratio is from 1: 3 to 1: 5. Engineering thermal calculations show that in a too narrow furnace, the incoming air simply leaves the combustion zone and is thrown into the chimney, which gives a significant loss of unit power. If you make the furnace too wide, then it is difficult to achieve good combustion closer to the walls of the combustion body. Only the central part of the fuel bookmark will burn out, the pancake will definitely sag and jam in this place, the combustion process will stop. Oven diameters from 300 to 800 mm are considered optimal.

2. Δ – case wall thickness. This parameter is especially important if the stove is planned to be “dressed” 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 when the stove will serve only for local heating of the room by direct heat transfer, the wall thickness can be even lower - bubafoni is often made from ordinary metal barrels. However, this necessarily leads to a loss of power - thin walls of a large area give a temperature drop above the "pancake" and the effective afterburning of pyrolysis gases may be lost or significantly reduced. In addition, hot gases in the bubafon seep 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 the order of 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. The parameters of the air distribution devices. It is a mistake to believe that they are limited only by the diameter of the cut out "pancake" - its thickness is also important, since how this part must have a good heat capacity - it is in this area that the final heating of the supplied air takes place.

Yes, for start - diameter disk. Calculations show that the optimal gap between it and the stove wall will be the value FROM = 5%D. For example, if the inner diameter body cylinder is 400 mm, then the gap is required by 20 mm 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 knot will simply sink into the combustion zone, extinguishing the fire, and a knot that is too light will not create a reliable clamp. And this may end up with the ignition of all fuel or even reverse combustion, for years the flames will go out through the air supply 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 relationship here, but you can focus on the following values.

If a cylinder of a different diameter is manufactured, then the thickness is easy to calculate proportionally, bringing it, of course, to the standard thicknesses of the produced metal sheets.

However, if there is a desire to make a really efficient stove, then it is better to make them in the form of clockwise-curved blades - 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 afterburning of pyrolysis gases. The very design of the created air channels is also important. The simplest is the cruciform arrangement of channels with side shelves of the desired height.

And this is a completely unsuccessful example of the manufacture of an air distributor

And this is an example of how not to do it in any case. The edges of the "pancake" are not processed, the metal is very thin, and the shelves of the corner, on the contrary, are extremely high. In fact, the entire bubafoni effect is lost - most likely, such a detail will lead to extensive burning of the fuel bookmark.

4. The next most important feature is chimney outlet diameter, or more precisely, then the area of ​​\u200b\u200bits section (in the diagram - S).

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

Basic formula: S=1.75E

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

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

The value itself E is defined by the following formula: E=M × e.

— M- the mass of the fuel bookmark in the stove.

— e is the 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 for stacking the type of fuel, i.e. its specific gravity per unit volume.

M = Vf × mf.

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

— mf– fuel loading factor (kg/dm³).

Indicators e and mf are reference values. For example, these data for some common types of solid fuels are given in the table:

Type of solid fuel	mf - specific coefficient of backfill, kg/dm³	e – specific heat transfer, kW/h
standard size firewood, aspen	0,143	2,82
coniferous shavings or sawdust	0,137	3,2
alder pellets	0,285	3,5
hard coal brand WPC	0,4	4,85
hard coal grade SSOM	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 cross section of the chimney for a homemade bubafoni from a conventional gas cylinder, in which D= 300 mm Hf= 600 mm. Remains another value is the volume of the loading chamber. Its height (in the diagram - Hf) is usually taken as ⅔ of the total height of the stove H. The volume is calculated according to the usual formula - the cross-sectional area of ​​\u200b\u200bthe cylinder multiplied by the height: Vf = πD²/4× H f.

Vf =π × 3² × 6: 4 = 42.39 ≈ 42 dm³.

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

The total mass of the furnace loading with coal: M\u003d 42 × 0.403 \u003d 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 up to 100 kW.

Thus, the cross-sectional area of ​​\u200b\u200bthe chimney for the stove in question is necessary:

S\u003d 1.75 × 100 \u003d 175 cm². From here it is easy to calculate the diameter of the pipe - in this case it will be 14.93 cm or, with reduction to the standard pipe size - 150 mm.

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

5. Main parameters of the air supply pipe. Its diameter ( on the chart - d) with some hardening ÷ can be taken as 0.5 ÷ 0.55 of the diameter of the outlet pipe. Thus, in this example, a 76 or 80 mm pipe can be used.

The pipe will be welded into the “pancake” of the air distributor. It is recommended to place its lower cut on the same level with the lower edges of the air guides. To avoid excess air inflow in the center, which can create an unnecessary cone-shaped zone of enhanced combustion, the pipe outlet can be narrowed, for example, by welding an unnecessary steel gear with a narrow bore here, and the main air flows can be redirected between the blades (channels). So the distribution of 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 at least 80×δ .

- With the “piston” completely lowered down, the air duct pipe should rise to a height above the upper cut of the collar q = L + 150.

In our example, we get the following:

• Suppose, after manufacturing the collar cylinder (usually they are made of galvanized sheet) and trying it on a pipe with pressing to one side, we got a clearance of 2.4 mm. Thus, the gap created δ 1.2 mm is obtained on each side.
• Based on this, the height of the collar ( L) must be at least 1.2 × 80 = 96 mm.
• The part of the pipe protruding above the collar - q= 96 + 150 = 246 mm.

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

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

If multi-fuel is planned, then often a similar damper is placed on the top cover of the stove. The combustion of pyrolysis gases emitted by some fuels may require an additional "portion" of air.

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

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

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

• The height of the lower edge of the loading door from the lower edge of the cylinder (in the diagram - hm).

Hm = Hf +h+σ + 30 mm

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

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

hm = H – Hf –i.

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

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

door height ( ha) is calculated like this: ha =h+ σ + 100÷150 mm.

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

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

By the way, a lot of performers and the removed cover and the seized "piston". Maintenance is less, but the work of making bubafoni is greatly simplified. In order to somehow facilitate the process of loading and cleaning, handles are welded to the stove cover.

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

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

An approximate scheme for installing a stove - bubafoni

• It does not matter whether such a stove will have welded legs, or it is planned to simply put it on the lower end part, the base must have pronounced refractory qualities. The combustion of fuel in the bubafon stove goes up to the lower boundary of the cylinder, and the bottom, of course, is very hot from this. An ordinary concrete screed will not suit you in any way - crumbling and cracking will surely begin soon. This means that it will be necessary to lay down a kind of "podium" of refractory fireclay bricks.
• The height of the chimney must be at least 4.2 m, otherwise the quality of draft will decrease, which will give a sharp decrease in heat transfer due to an inferior 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 approach too close - the thermal equilibrium of the system may be disturbed.
• The pyrolysis process is always accompanied by a rather 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 gaps), a special knee - collection moisture. Its height, from the point of insertion, is not less than 300 mm. An outlet valve must be installed from below, for regular prophylaxis - draining the 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 someone, such calculations of the stove - bubafoni may seem excessively cumbersome. However, this is not at all difficult - it is worth devoting a few evening hours to such a process, armed, and your own project, based on an almost scientific approach, will be ready. But there is no need to doubt the performance of the future heater.

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

Bubafonya stove from a gas cylinder ...

Knowing the parameters of this cylinder, it will be easy to “fit” all other parts and assemblies 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 draw up your project from scratch, exactly the size and power that are required to heat a particular room.

Prices for sheet bending machines

sheet bending machine

Video: bubafonya stove from a gas cylinder

One of the simplest options is a 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 at the barrels is small, and, of course, it will not be possible to obtain too significant heat transfer from such a bubafoni. Its efficiency is also not very significant, but on the other hand, a large volume of loading and the duration of work at one “gas station” up to 12 hours is what is needed for heating some outbuildings or utility rooms.

Another convenience of this design is that the barrels have a single standard size. In the event of a burnout of the most vulnerable area - the walls (which should 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 subject to rapid wear, can easily be rearranged into a new case.

So, first of all, you need to remove the top cover from the barrel. It is best to carefully cut the weld 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 knocked out with a sledgehammer somewhat inward, and on the lid, on the contrary, they expand the rolling.

The edges of the case are processed ...
... and a cut lid

As a result, the lid should sit tightly on top of the case.

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

The lid can be done in a slightly different way. In this case, it is cut to such a diameter that it fits snugly into the body cylinder. A metal plate of arbitrary size and shape is welded on top - it will become both a support and a kind of “plate” 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 cover. Try to keep the edges as even as possible.

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

Metal profiles are welded from the bottom of the "pancake" - air ducts. The figure shows a channel, but with such a large diameter of the stove, it is still preferable to stop at the option with curved blades from 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 an axis is attached to the top of the air supply pipe. For ease of use, it is recommended to provide for fixing the damper position in the desired position, for example, with a wing nut.

More advanced damper - with a fixing "lamb"

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

When welding a chimney pipe, it is imperative to achieve complete tightness of the seam.

In fact, all bubafoni nodes are already ready. except for the chimney, of course. It remains 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 to both the lid and the stove body itself.

Video: a variant of the bubafoni stove from a barrel

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

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

• The risk of getting an accidental burn from a red-hot body of the stove will be significantly reduced.
• This design will create a powerful convection flow, which will contribute to the rapid heating of the room.

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

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

• heat exchanger must be purchased separately.

STROPUVA S 40

The best long-burning boiler of 2019, capable of giving warmth to the hearth for 70 hours. This will require about 50 kilograms of firewood. Not too economical, but very convenient and efficient. For country houses the best option is not found. By the way, do you often see 95% efficiency? So, here are the indicators for this model. Heats up to 400 square meters. Operates on coke, wood, coal. Judging by the comments of users, this model fully meets expectations, despite the high price tag. Attracts 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 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 of great interest to summer residents and owners of commercial buildings. It is able to heat rooms of 150 square meters. m. One bookmark 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 more than that of competitors.

• high efficiency;
• high coolant temperature;
• prolonged burning of fuel.

• little pressure;
• mechanical control.

I propose for consideration such an interesting design of the furnace, which was called "Bubafonya". Such a stove is classified as a long-burning stove, and you can heat it with almost anything, from ordinary firewood to sawdust, grass, bark, and so on. The peculiarity of the furnace is that combustion in it occurs from top to bottom, and not vice versa, as in classic furnaces. The air supply is also carried out from above, and the air, until it reaches the point of burning firewood, is heated.

The design is also interesting in that the firewood is pressed from above with a plate with an impeller. Thanks to the plate, a combustion chamber is obtained, the plate presses on the firewood and the combustion chamber decreases depending on the degree of combustion of these firewood. And the impeller is needed so that the incoming air forms a vortex at the combustion point. Of course, the design is quite sophisticated and it is difficult to fully understand the principle of operation of such a furnace, but, according to its owners, it works quite interestingly and efficiently. Consider how to make such an oven from a gas cylinder!

Materials and tools used by the author:

List of materials:
- two gas cylinders;
- inlet pipe for air supply;
- outgoing chimney;
- thick sheet steel.

List of tools:
- welding machine;
- Bulgarian;
- a drill with good drill bits for metal;
- roulette;
- marker;
- clamps.

The manufacturing process of the Bubafonya furnace:

Step one. Gas cylinder preparation
Working with a gas cylinder implies a high danger, if you just start cutting the cylinder, it is highly likely to explode. There are many ways to clean the balloon. The easiest way is to fill it under the neck with water and start cutting directly with water. But at the same time, you need to be careful and try not to wet the grinder, as you can earn an electric shock.

Some more craftsmen thoroughly wash the balloon with water and detergents. Hot water must be used so that combustible substances evaporate. But this procedure must be repeated several times.

In any case, first remove the tap and drain the contents from the cylinder. What flows out is a combustible substance, gasoline is similar in properties to gasoline. Therefore, avoid open flames.

Step two. Cutting and welding
When the cylinders are prepared for cutting, we arm ourselves with a grinder and get to work. We cut off the necks of both cylinders. One cylinder will be the main one, and we will cut off a piece from the second one to lengthen the furnace. When everything is ready, weld all the parts together well. As a result, the resulting design from the author has a height of about one meter.

Step three. Cover making
To make the lid, we need the top of one of the cylinders. In order for the lid to be well fixed on the cylinder, we need to make a ledge in its inner part. To do this, cut off a piece from the balloon, and then cut and narrow the resulting rim so that it goes inside the balloon. That's all, now we weld this to the inside of the lid. As a result, we get an excellent cover, which is tightly and securely installed on the furnace.

Step four. Installing a chimney
In the upper part of the furnace, you need to make a hole for the chimney. The author makes similar holes with a drill. We drill a series of holes, and then knock out the part with a hammer. The hole can then be finished with a file. That's all, it remains to weld the chimney.

Step five. Production of the air intake
The air intake is a piece of pipe with a plate at the end, the pipe passes through the furnace to the firebox. We select the desired pipe and cut off a piece of suitable length. The length of the pipe should be slightly longer than the length of the furnace so that it does not completely fall into the furnace when all the fuel has burned out.

Next, we make a separating plate, it must be made of thick sheet steel, since there will be a high combustion temperature inside the furnace. We need to cut a circle of such a diameter that it enters the balloon with some clearance. The size of this gap, unfortunately, is unknown. We cut out the circle by drilling holes, it would be nice to have a drilling machine here.

In the center of the round timber we make a hole for the inlet pipe and weld it. An impeller is also installed on the plate to evenly distribute air throughout the combustion chamber. For its manufacture, you can use a corner or other similar material.

Step six. Finishing the oven lid
The stove is almost ready, it remains to make a hole in the lid for the intake pipe. The gap here should be small, but at the same time, the pipe should easily pass through the cover. You also need to weld two thick wire handles to the lid.

That's all, after that the oven is ready. Firewood is loaded from above, ignited similarly from above. The furnace closes and the slow and efficient combustion of the fuel begins.

Of course, at the bottom of the stove, you still need to make a door so that it is more convenient to set fire to the stove, monitor the combustion process, and also rake out the ash. But the door must be airtight, since, as planned, the air supply comes from above.

That's all, the project is over, leave your opinions about this design, and also write reviews if you have such a furnace. Good luck and creative inspiration if you decide to repeat. Don't forget to share your