Metal heating stoves for a country house. Which metal stove is better for the home - varieties, differences, advantages and disadvantages. Video: the theory of burning wood in a metal furnace

The problem of heating a small country house or change house is usually solved in two ways - electric heaters or a metal wood-burning stove are installed. Build will be twice - three times more expensive. The least expensive option is to make a heating potbelly stove for giving yourself, using ready-made drawings.

Introducing 2 original designs designed and tested by our expert. The main advantage of heaters is the ability to fully heat 2 adjacent rooms.

Suspended long burning stove

The wood stove shown in the drawing consists of the following elements:

horizontally located firebox with a volume of 50 liters;
from below, an ash pan is welded to the firebox, equipped with a separate door;
vertical secondary chamber with a chimney pipe;
an inclined air channel laid through it;
the third chamber with heat exchange fins and heated air outlet pipe.

Note. The furnace in the drawing is shown in section. The method of joining two pipes is arbitrary, the internal through hole is a square section, 15 x 15 cm in size.

A fan is installed on the horizontal air pipe Ø100 mm, provided in the vertical part of the potbelly stove. A corrugated aluminum pipe is connected to the outlet fitting of the heat exchange chamber, which blows hot air into the adjacent room.

The principle of operation of the iron stove is based on the intensive heating of the air flow created by the fan. How the heating unit works:

Firewood 0.5-0.7 m long burns in the firebox, the amount of air supplied is regulated by the ash pan door.
Combustion products penetrate into the second chamber, where pyrolysis gases are burned. Plus, heat is transferred to the outer walls and the inner inclined pipe. Further, the spent volatile substances are thrown out into the street through the chimney.
The air blown by the fan is preheated in an inclined channel, then enters the main heat exchange chamber located directly above the firebox.
Having finally warmed up from the internal ribs and the red-hot vault of the firebox, the air flow exits through the vertical pipe and is directed to the adjacent room.

A home-made stove - a potbelly stove of this design heats the room around it in the traditional way, and the next one - due to forced air heating. The duration of burning is ensured by a decent volume of the firebox (50 l), where long thick logs are placed.

A long horizontal firebox allows you to put almost meter logs into the potbelly stove

The above-described metal stove develops a thermal power of about 7 kW, that is, it is able to heat a summer house, garage or change house with an area of 60-70 m². The stove is installed inside a larger room, the air pipe is laid in a smaller one.

We select materials

The round body of the stove is made from an old propane tank or a thin-walled steel pipe with a diameter of 300 x 5 mm. In the second case, the length of the firebox can be increased up to 1 meter.

Advice. It is better to find standard 50 l cylinders from liquefied gas, 2 pcs will be used to assemble the stove. A pipe Ø300 with a wall thickness of 5 mm is a non-standard product, it will take a long time to look. A more affordable option Ø300 x 8 mm will be too heavy.

For the manufacture of an iron furnace, the following additional materials will be required:

sheet metal 3 mm thick - for doors, ash pan and hot air chamber;
fittings of a periodic profile (the so-called corrugated) Ø10 ... 12 mm - to reinforce the grate;
a piece of pipe Ø76 x 3 mm, 0.6-0.7 m long;
cuttings Ø100 mm - for chimney and air pipes;
rolled metal waste - corners, small channels, professional pipes for stove legs.

Installation of factory locks (left) and sealing with graphite-asbestos cord (right)

Locking door handles are easier to buy ready-made than to make them yourself. An asbestos cord will be needed to seal the porches. Fan - any household model with a capacity of up to 50 m³ of air per hour.

Making a potbelly stove - step by step instructions

When using gas cylinders, the first operation will be the safe opening of these vessels. Procedure:

Fully open the valve, turn the tank upside down in order to drain the remaining condensate as much as possible.
Unscrew the valve with a pipe wrench, fill the cylinder to the top with water.
Using a grinder, carefully cut off the sidewall, focusing on the factory weld.

Reference. Propane is heavier than air, so it won't evaporate on its own. The remaining gas is displaced from the vessel only by water, cutting is carried out with a filled tank.

In fact, it is not necessary to saw off the cover, since the design does not provide for the installation of an internal grate. You can immediately cut an opening for mounting the door or a side square hole for the exit of flue gases.

How to make a long-burning stove for a summer cottage with your own hands:

Perform the preparatory work - cut the slots of the grate, technological holes for the passage of gases and the installation of doors. Saw the second cylinder, fitting the future secondary chamber under the firebox.
Wood stove drawing - top view
Weld reinforcements from reinforcement or profile on the grate, as shown in the photo. Otherwise, when heated, the metal will begin to bend.
Attach an ash pan from metal strips and furnace legs, guided by the drawing.
Make the doors and frame as shown in the picture. Seal the porch with an asbestos cord, lay basalt insulation inside.
Make holes in the vertical body, place a Ø76 mm pipe inside, observing an angle of 35…40°. Hermetically seal the ends, dock the finished element with a horizontal balloon.
From above, weld several strips of rolled metal scraps to the roof of the firebox - they will serve as ribs for the air heat exchanger. Make the camera body, attach all the pipes.
Weld the frame, install the firebox and ash pan doors.

Advice. Do not deviate from the drawing and do not increase the size of the heat exchange cavity - the heating efficiency will decrease. The mounting angle of the inclined channel is given approximately, the main thing is to insert the pipe between the side walls and scald well.

The branch pipe for installing the fan does not have to be made long (according to the diagram - 20 cm). To prevent the impeller from overheating, it is enough to connect the supercharger through an aluminum corrugated pipe. How to weld the stove yourself, look at the video of our expert:

We placed a review of the operation of the stove in real conditions at the end of the publication - the video tells about heating a garage 6 x 12 m.

Vertical oven with water circuit

This potbelly stove can work on wood, coal and briquettes. The unit is made from one 50-liter cylinder, installed vertically. Inside the upper part there is a heating chamber with heat exchange fins through which water or air flow can be driven. Briefly list the technical characteristics of the stove:

heated area - up to 40 m²;
water circuit power - 2 kW (in the maximum combustion mode);
the volume of the furnace is approximately 25 liters;
the thickness of the metal of the partitions is 4 mm.

The principle of operation of the furnace is simple: the flame heats the side walls of the unit and the bottom of the upper chamber with welded metal plates. Water is forcibly supplied through the pipe into the cavity or, it takes away heat from the heating surfaces, then it is sent to heating devices (as an option, home-made registers from smooth pipes).

Clarification. Instead of water, air can be driven through the heating plates - the stove will work in heat gun mode.

The potbelly stove is suitable for heating 2 rooms of a small country house, workshop or change house. Duration of burning in the mode of maintaining heat - 2 ... 3 hours, depending on the quality and type of fuel. The number of attached heating radiators - 2 pcs. 0.8-1 kW each.

Drawing and diagram of the operation of a vertical round furnace

What to cook a country heater from

In addition to a 50-liter propane tank, you will need the following materials for assembly:

sheet steel grade St20 4-5 mm thick - the bottom of the water chamber;
the same, 3 mm - doors, frames, heat exchanger fins;
fittings Ø12…16 mm on the grate;
cutting pipes with a diameter of 100 and 32 mm for the manufacture of connecting pipes;
asbestos cord, fire-resistant basalt fiber.

To connect a water heating system, you can supply Ø32 ... 20 mm spurs with a finished thread. Before starting work, carefully disassemble the cylinder - dismantle the gas valve and pour water into the container.

Iron scrap ribs play an important role - they increase the working surface of the heat exchanger

The procedure for conducting assembly work

The manufacture of a potbelly stove begins with the opening of the cylinder - here you will have to cut off the upper part along the existing weld. Then we work according to the instructions:

Make square holes in the side wall according to the drawing.
Prepare the details of the stove from metal - a round partition Ø30 cm, frames for doors 80 mm wide and the doors themselves. Attach the frames by welding to the body, as shown in the photo.
From the fittings, weld the grate, strictly adhering to the internal size of the vessel. Then the grating will lie tightly on the welding joint without additional supports.
Weld hermetically 2 threaded fittings to the cut off cover, where the water system lines will subsequently be connected.
Install the round blank on the end of the cylinder, scalding the seam from the side of the firebox. From above, attach heat transfer plates from scraps of a metal sheet.
Put the cover with fittings in their original place, mount the doors and weld the chimney pipe. For beauty, the stove can be painted with a black heat-resistant compound (sold in an aerosol package).

Reminder. Do not forget to plug the upper opening of the tank, from which the valve was previously turned out.

Install the stove and chimney in accordance with fire safety regulations. Cover the finish of combustible materials near the potbelly stove with galvanized sheets. Also keep a distance of 0.5 m from the steel chimney to the wooden ceiling. If applied, then the indent is reduced to 38 cm.

When installing water heating, consider an important nuance: without forced circulation, the coolant in the heating chamber of the furnace will quickly boil. Connect the batteries in accordance with the diagram, put a dirt filter and a circulation pump on the return line. If you plan to heat the cottage periodically, fill the system with antifreeze.

Scheme of connecting the heating circuit of the potbelly stove to the radiators

Advice. Choose a pump for pumping water through 2 radiators with a minimum capacity, the volume of the expansion tank is up to 5 liters.

Conclusion

A metal home-made potbelly stove is a convenient and relatively inexpensive solution for heating a summer house or a temporary change house. The stove looks good in a room with a simple finish, and if necessary, it can be quickly dismantled. If you want to heat a two-story country house, it is better to use a channel-type brick oven - “Dutch”.

When asked how a metal stove differs from a stone one, many answer with a smile and without the slightest hesitation - the material of manufacture. For such an answer, you can put a three on a five-point system for assessing knowledge. To get a higher score, check out the main and fundamental differences, this knowledge will be very useful to you when making a metal stove for a bath with your own hands.

The stone oven is made of heavy bricks, therefore, it has a large mass. And all bodies with a large mass are characterized by significant inertia - they heat up for a long time and give off heat for a long time. For a bath, this is not bad, but only on one condition - the device of the firebox must provide the maximum temperature for burning firewood, otherwise it will take a long time to heat the premises.

The metal furnace, on the contrary, has a small mass, heats up quickly and cools down just as quickly. These features put forward fundamentally new requirements for the firebox, the firewood in it should burn as long as possible. This is the only way to keep the oven hot for a long time.

Another important requirement for the firebox is related to the characteristics of steel. When heated to only + 150 ° C, martensite begins to decompose, it recrystallizes and polygonizes, the physical properties of the metal change.

Look at the table, at this temperature the metal furnace does not change color, it seems to us that everything is fine, but this is no longer the case. Low-temperature tempering occurs at metal temperatures up to +250°, steel loses its resistance to dynamic loads.

The dark brown color of the furnace indicates that the metal has heated up to a temperature of +550°C, and at these indicators, medium-temperature steel tempering begins, martensite turns into ferrite and cementite. Crystalline transformations of a metal change its linear characteristics. Have you noticed that sheet iron, after strong heating and cooling, does not return to its original dimensions? It can swell, lose linearity, etc. The appearance of the stove becomes “very original” and far from the original.

But quite often, the metal oven heats up even more and turns bright red. This color appears at a heating temperature of +900°C. And this is already a high tempering, the metal becomes very soft and ductile, the phenomena of residual deformation increase significantly. The oven may warp, the welds may not withstand the resulting static forces. How to prevent such negative phenomena? It will not be possible to completely get rid of them, but there are ways to minimize them. They will help increase the operating time of a metal stove and improve the comfort of bathing procedures by increasing the time to maintain a favorable temperature in the room.

We are sure that this knowledge will help you minimize the negative consequences of heating the metal furnace too much. This can be done in two ways: by special preparation of the metal and by the features of the furnace device.

Metal pretreatment

After all the individual elements of the furnace have been cut out, the most heated parts must first be released. The sides and top parts and the firebox door heat up the most. Heat them in any way until red and cool slowly. After vacation, the sheets may warp a little, it's not scary, trim them with a hammer to their original state. Check the dimensions again, if they have changed within noticeable limits, cut to the desired parameters. This simple method will eliminate the warping of the stove during its operation.

Features of the design of the furnace of a metal furnace

Most metal stoves produce the maximum amount of heat in the minimum time, the wood burns out very quickly, the surfaces heat up to high temperatures. It is impossible to maintain a normal and stable temperature in the steam room - you often have to add firewood. The room is either too hot or too cold. Why is this happening? Such furnaces in most cases have grates. Their presence is justified in stone ovens, we have already mentioned that these ovens need to be heated quickly. Strong burning of the flame is provided by a large amount of air entering through the grate into the flame.

Grids are made from metal rods, sheet metal with numerous drilled holes or cast iron, they differ in the size of the holes, etc.

The firewood lies on the grate, the air supply is not regulated by anything, on the contrary, all measures are taken to increase the draft, which automatically speeds up the combustion process. The upper part of the oven heats up the most, the sidewalls slightly less, and the bottom and front part heat up slightly.

Sheet steel prices

Sheet steel

Such a combustion mode has an extremely negative effect on both the duration of the operation of the stove and the comfort of staying in the steam room. You have to periodically fill the fire with water, if there is not enough water, the flame quickly flares up again, if there is a lot, the burning may stop altogether. In a word, a bathing day instead of pleasure brings a headache.

What do we offer? The solution is very simple - do not make grates with a blower, let the firewood lie at the bottom of the stove, and not on the grate. Seal the firebox door as much as possible; you can use asbestos cord or mineral wool around the perimeter.

Make holes in the firebox door with an ordinary movable damper to regulate the amount of air supplied. One bookmark of firewood in such an oven will burn for more than an hour, it is possible to regulate the temperature of heating surfaces. In addition, the entire area of \u200b\u200bthe stove will warm up. Due to the absence of a grate and an ash pan, work on the manufacture of the furnace was simplified, and efficiency and ease of use increased.

As you can see, all the knowledge came in handy for us, they can be used not only during the manufacture of the sauna stove. We have dealt with the theory, it's time to move on to practice.

Brief description and dimensions of the metal stove

Our design will have a separate tank for heating water and a heater built into the top of the stove. The flame heats the heater from all sides, which significantly increases the efficiency of the stove. You can take arbitrary sizes, consider the parameters of the steam room and the number of people washing at the same time. For example, we give the dimensions of our stove.

External stone. Width 50 cm, length 50 cm, height 80 cm.
Internal stone. Width 40 cm, length 40 cm, height 50 cm. The distance between the walls of the inner and outer heater is five centimeters around the perimeter.
Bake. Width 50 cm, length 90 cm, height 50 cm. You can change the length of the stove, make it only for an external heater 50 cm long (then the water tank will have to be mounted on stops from the side) or increase the length to increase the volume of the tank.
Water tank. Width 40 cm, length 50 cm, height 60 cm. 120 liters of water are placed in the tank, which is quite enough for washing three or four people. Of course, hot water must be diluted with cold.

Instructions for the manufacture of a metal furnace

Step 1. Prepare materials. For manufacturing, you need sheet steel, the thicker the better. But this can be very expensive, we recommend using sheets with a thickness of 1.5÷2.0 mm.

Metal sheets 2 mm

Step 2 Make a sketch of the stove, showing all dimensions and parts. Count the number of parts and their total area. This will help you decide on the need for sheet iron.

Scheme - an example of a sauna stove

Step 3 Transfer the dimensions to the metal, cut out all the elements of the furnace. Strictly observe the angles, they should be 90 °, make the opposite sidewalls as identical as possible. You need to cut metal with a circular grinder, follow the safety rules. The grinder is a very dangerous tool, you should not joke with it, as a result, you can get too severe injuries. Burrs after cutting the workpieces should be removed. Before starting welding, double-check the quantity and dimensions of all parts.

Furnace welding

Perform work on a flat area, free the workplace from foreign objects. Let's start with the manufacture of the heater for the stove.

Step 1. Place two sidewalls on the edge at a right angle, start making potholders.

Adjust the current strength, the electric arc should not overheat the metal - the seam will turn out to be uneven and fragile. Tack a few millimeters, 4 ÷ 5 tacks are enough for one corner. Constantly check the position of the sidewalls. After cooling, the weld leads the sheets to the side, align their position. Check the corners with a square. In the same way, grab the two remaining sides of the heater.

Step 2 Put the two prepared blanks together, adjust the corners if necessary and grab the opposite edges of the heater. You have got a heater box, it remains to make the bottom and the lid.

Four connected blank sheets forming a box

Step 3 Grab the bottom and lid. During manual cutting of blanks, it is impossible to achieve ideal dimensions, there will always be deviations. This is not scary, before tacking the bottom and cover, install them in such a way that the difference in dimensions is approximately the same on all sides. Slits of a few millimeters will weld without problems. To prevent the lid from falling into the box, put one side on any stand, as long as it is thin and does not disturb the desired position of the part. Make a few tacks on each side of the heater, as always, pay attention to the position of the elements and correct deviations if necessary.

For the bottom of the inner heater, it is better to take a sheet 10 mm thick. It accounts for the main “ular” of the flame, a too thin bottom can burn out quite quickly and smoke will begin to flow into the steam room. When the heater box is fully tacked, apply full seams.

Step 4. Make a door in the stove. Lay the box horizontally and make a markup. You can cut a hole with a grinder or welding.

In our version, the heater consists of two parts: internal and external. The outer one should have dimensions around the perimeter larger than the inner one by about 10 centimeters for the passage of flame and smoke into the chimney. The inner heater is installed in the outer one on pipes, the diameter of the pipes is arbitrary.

Step 5. Make holes in the lower part of the outer heater for pipes, on which the inner heater will stand. If you don't have pipes, you can use metal bars or rebar. Make sure that the holes are horizontal and at the same height on both sides of the sides of the outer heater.

In the same way, grab the outer heater, the furnace firebox and the water tank. Cut holes in the firebox for firewood. We recommend making holes in such a way that the cut parts of the sheet can be used as doors. To do this, make holes in the furnace 1 cm larger than in the heater, from this blank it will be possible to make a door to it - material is saved.

Video - Making a metal stove for a bath (part 1)

Assembly of individual elements of the furnace into a single structure

Step 1. Prepare four plates for welding two heaters. The dimensions of the plates along the length must correspond to the dimensions of the opening of the external heater.

Step 2 At the top of the outer heater, cut holes for the chimney. The dimensions of the hole must match the pipe you have and provide the necessary draft in the furnace.

Prices for chimney pipes

flue pipe

Step 3 Along the perimeter of the hole in the stove for the heater, weld metal strips about 2 centimeters high, the dimensions of the opening should correspond to the dimensions of the outer heater.

From the inside of the firebox, weld a corner 45 × 45 m, one side of the corner should go into the hole for the heater and form a square. The side of the square should be 0.5÷1 cm smaller than the dimensions of the heater. The structure will rest against these shelves in the furnace opening. To increase the sealing of the meta-installation of the heater, use sheet asbestos, cut out strips of two centimeters wide from it and place it between the bottom of the heater and the stops from the corner. Detachable connection will facilitate the installation of the stove in the steam room. The structures of the stove are made of thick steel, they are large in size and weight; it is impractical to weld the heater to the stove. It is much more convenient to make it collapsible / collapsible, this will facilitate transportation and installation.

Step 4 Weld the firebox door on the hinges. Double seam weld all pre-made structures. The seam is better to put outside and inside.

Step 5 Insert the inner heater into place, it should stand on the pipes and have a vertical position. Using the prepared plates, connect the holes of the inner and outer heaters. If the fastening of the internal heater is in doubt, fix it from above with pieces of metal, squares or fittings. These mounts will be hidden, you can use any metal scrap.

The hole is covered with a door. Asbestos cord around the perimeter of the door, the lid is bolted

Step 6 Weld the top cover of the outer heater. Cut a hole in it for the chimney pipe. Check the quality of all seams, correct gaps if necessary.

The stone is almost ready. The backwardness is only to make a technological hole for cleaning the soot falling from the pipe and to think over the installation of the furnace. Soot will accumulate on the lid of the inner heater. Make a hole on the side of the outer wall of the heater, close it with a bolted lid, use an asbestos cord to seal it. Gently grind all the corners with a grinder, remove the burrs.

We offer to install the oven on metal legs. The height of the legs is at least 40 centimeters, asbestos must be placed below, a metal sheet on top. These are fire safety regulations.

Video - Stove for a bath (stages of assembling a double heater and installing it on a welded combustion chamber)

Video - Sauna stove (final part)

We have already mentioned that each master in the course of manufacturing the stove can make his own changes and adjustments, taking into account his own preferences and the individual characteristics of the steam room. The changes concern not only the dimensions of the furnace, but also its design. We give a few hints for possible use.

It is better to make the legs in the form of a longitudinal slide - the pressure on the flooring is significantly reduced, the loads are distributed evenly over several floorboards. This is very important, the stove itself is quite heavy, and you also need to keep in mind the weight of stones and water. For the manufacture of legs, any available metal of suitable sizes is suitable, and for the sled, you can take a 50 × 50 mm square. The ends of the sled should not protrude beyond the perimeter of the stove, otherwise you can injure your legs.

Refractory bricks can be placed on the bottom and sides of the stove - the metal heats up less and the heat lasts longer. There are two types of refractory bricks: heat conductive (heavy) and heat insulating (light). The latter are used for laying smelting furnaces, they keep the surfaces cold, despite the huge temperature inside. Make no mistake, do not take such materials. A fire-resistant brick for a bath stove should conduct heat well, pay attention to this. If you plan to lay bricks, then increase the size of the firebox by the size of the brick.

Refractory brick prices

refractory brick

Firebox and heater doors can be made from plates obtained after cutting holes. To do this, make the cuts as even as possible, use thin discs to reduce the width of the slot. Working with them is more difficult and longer, but in the end you will still save time - you won’t have to waste it on making individual doors. It goes without saying that metal is also saved.

The dimensions of the doors will be smaller than the dimensions of the holes by the width of the cut, the doors can “fall through” into the firebox or heater. To exclude such situations, door stops should be welded on the reverse side of the holes. You can use narrow strips of metal. It is advisable to weld the stops around the entire perimeter of the holes, and not at several points, in this way you will increase the tightness of closing the doors.

It is better to make from stainless steel, for welding stainless steel you need to use special electrodes. Adjust the current of the welding machine specifically for stainless steel, remember that it is more difficult to cook it, some experience is required.

Prices for stainless steel tanks

stainless steel tank

If small children are washing in the bath, be sure to make a protective fence around the stove. It can be portable or stationary, it doesn't matter. The main thing is that the fence guarantees the safety of children.

If during the operation of the stove it turned out that its power is not enough to heat the room - do not be discouraged. The heat transfer performance of the stove can be significantly improved by increasing the effective area. Weld any metal plates on the sides and top, they will act as heat exchanger radiators. There is another way to increase heat transfer. To do this, you will need curved pipes with a diameter of about 50 centimeters. Weld them to the sides of the stove, one end of the pipe should be located under the stove, and the other above it. As a result of the temperature difference, draft will appear in the pipes, cold air is drawn in from the floor under the stove and thrown out hot above it. The stove will work on the principle of the Buleryan stove.

We recommend making an adjustable air supply on the firebox door. The easiest way is to make a blower from a pipe. You will need a piece of pipe ≈10 centimeters long and a piece of sheet metal of the same size. Make a hole in the middle of the door for the diameter of the pipe. From sheet metal, cut a circle with a diameter a few millimeters smaller than the nominal diameter of the pipe. Drill two holes in the walls of the pipe, they must lie strictly on the same line and on the axis of the pipe. The distance of the holes from the end of the pipe is at least half the diameter, otherwise the damper will not completely block the gap, which will impair the ability to adjust the amount of fresh air supply.

Insert a piece of wire rod of the appropriate diameter into the holes, bend the upper end in the form of a handle. Weld a circle cut out of sheet steel to the wire rod, fix the manufactured damper to the hole in the firebox door.

There is another way to make adjustable door openings. Drill holes with a diameter of 10 ÷ 20 mm in the lower part, the centers of the holes should lie on the same line. Weld a metal plate from the bottom and top of the holes, the distance between the plates and the door should be equal to the thickness of the valve. The plates will serve as guides for the valve. Open one or more holes as needed during the firing of the stove.

These are not all possible improvements to a metal stove, think for yourself and engage in technical creativity. This process brings real pleasure, believe the professionals.

Metal furnaces have a number of undoubted advantages and equally significant disadvantages. The former include an order of magnitude smaller or more price, high efficiency, light weight, high strength and advanced technology for processing the source material - metal. To the second - lack of "breathing", limited service life, increased danger and short heat dissipation after the flood. These factors give some consequences, which should be considered in more detail before starting to analyze the actual metal furnaces.

Advantages

Metal is a much more malleable material than ceramics, but comparable in strength. Metal can be melted and poured, drilled, cut, bent, forged; after forming the part, it does not require mandatory additional energy costs for firing it. There are many known methods for the production and processing of metal, and their scientific and industrial base is huge. Therefore, when creating a metal furnace, it is possible to apply almost without restrictions a variety of theoretical and design tricks to improve its technical and operational parameters without a significant increase in price. If the marginal average per season CFL of brick ovens is about 70%, then for metal 85-90% is not a wonder.

Note: based on modern environmental conditions, it is necessary to strive to obtain a furnace efficiency of at least 70%

The specific, per unit cross-section, strength of bricks and ceramics in general decreases sharply with a decrease in the thickness of the part, while for metal, on the contrary, it increases. As a result, such important furnace indicators as weight and cost per unit of generated heat are 10-20 times or more lower for metal furnaces than for brick ones. A good new metal oven for heating 100 sq. m of living space can be purchased for $250-300, and used for $50.

In addition, the metal oven is a one-piece construction, it can be transported ready for use, tilted, pushed, hit, even dropped without being damaged. That is, the metal furnace is mobile. At the place of operation, it does not require a foundation, and its installation is reduced to the withdrawal of the chimney into the smoke channel of the building. After the need has passed, the stove can be removed and placed in storage until the next occasion.

The thermal conductivity of the metal is high, and the total heat capacity of the furnace from it is small due to its small mass. Therefore, the metal stove warms up quickly and heats the room just as quickly. The same factor gives high efficiency: in a brick kiln, up to 20% of the fuel energy flies into the pipe during heating, until internal heat transfer is established in the massive body of the kiln and it begins to accumulate heat.

Further, the metal product is physically more uniform than masonry and is not porous. The metal furnace does not dampen, is not afraid of long breaks in the furnace, does not require accelerating fires after downtime. The actual absence, due to the high thermal conductivity of the metal, of internal heat flows in the body of the furnace, causes the rapid combustion of flue gases in it in a small volume of space, which facilitates the integration of a hob and water heaters into the furnace.

Finally, which is important for private owners, a metal factory furnace can be certified in advance for fire safety as a finished product. In this case, it is immeasurably easier to get permission from firefighters to use it, both in terms of nerves and money. There are models of metal furnaces of industrial production that do not require registration at the Ministry of Emergencies at all, if only the building had a gas duct separate from ventilation.

disadvantages

The main disadvantage of metal furnaces is the lack of "breathing". The brick oven, as it cools, absorbs moisture vapor, and when heated, it releases them into the air. Therefore, in a house with brick-stove heating, the relative humidity of the air itself is maintained within optimal health limits. A metal stove can be made to “breathe” a little by lining with brick, steatite (“soapstone”, soapstone), basalt or drywall, but the effect will be weaker, the strength of the stove will decrease, and its mobility will completely disappear.

Due to the low total heat capacity, the heat transfer of the furnace after heating does not exceed 2-3 hours. A metal furnace must either be heated all the time, or performed in the form. Both are a constant source of fire. When installing the stove in a residential area, this gives a round-the-clock danger of waste. In addition, a metal furnace can become red hot during operation, and this creates a fire and injury hazard. Therefore, the Ministry of Emergency Situations certifies home-made metal furnaces with great difficulty, and then only intended for installation in isolated non-residential premises.

The third significant drawback of metal furnaces is a short service life compared to brick ones. Chemically, metal is much less resistant than ceramics, and at high temperatures it reacts even more actively with substances that can damage it. The service life of a metal furnace with regular firing rarely exceeds 20 years; however, this pays off in reduced fuel costs and the ability to replace the stove without repairing the building.

About furnace metal

As you can see, it is the physical and chemical properties of the metal for the furnace for the furnace that largely determine its quality. Whether the stove will be purchased ready-made or made independently, the first attention should be paid to it.

Surrogates

In popular sources, you can find descriptions of stoves from ... aluminum milk cans. But for a more or less acceptable efficiency of the furnace, it is necessary to burn the flue gases. At the same time, a temperature of at least 400 degrees Celsius develops, and in furnaces that meet environmental requirements, at least 600. The melting point of aluminum is 660 Celsius; temperature tensile strength - 140 for structural aluminum and 160-210 for aluminum alloys. On this the question of aluminum furnaces can be considered closed.

plain steel

The temperature limit of strength and resistance of conventional structural steels is about 400 degrees during prolonged exposure; at 2 hours 600. Steel on the furnace comes with a thickness of 4 mm. But even in this case, it is impossible to talk about regular use: in frosty regions where an intensive firebox is needed, the stove can burn out before the end of winter. Some exceptions are long-burning furnaces, some of their designs make it possible to avoid prolonged heating of the furnace body above 600 degrees, and very hot parts in them are massive and replaceable. Such ovens are most often made by hand; some popular designs will be described below.

Heat resistant steels

Metal furnaces of industrial production are made of heat-resistant and heat-resistant steel. Modern special steels with a thickness of 1.5-3 mm make it possible to obtain a furnace service life of up to 20 years or more, its low weight, and the combination of heat capacity with thermal conductivity of furnace steels, with the correct design, guarantees high efficiency, up to 80%. Branded steel furnaces for sale are certified according to the requirements of the Ministry of Emergencies, for fire and injury safety they are quite suitable for the home. Their installation is most often possible simply on the floor and requires only a connection to the chimney. In most cases, they are equipped with a hob and a low-power hot water hot water register.

The design of such furnaces at first glance is available for repetition. But in order to do something like this yourself, even if you have the material, you need to master at least quite complex TIG / MIG welding technology and expensive equipment for it. Attempts to cook heat-resistant stainless steel in artisanal ways are meaningless: after remelting under an arc, the steel loses its qualities and the stove cracks at the seams faster than the tin stove burns out.

However, it is quite possible to make a furnace yourself using heat-resistant steels, and this will greatly increase its reliability and durability. We are talking about air distribution devices for long-burning stoves of the Slobozhanka type, see more details below. Expensive material will take a little, you can pick up and trim. And the connections in this case can be made on a mustache, rivets or in a fold.

Cast iron

Cast iron in a furnace is both metal and non-metal at the same time. From the metal in it remains a low cost and the ability to carefully, without dropping or hitting, move the stove. Cast iron has in common with brick not only brittleness, but also low thermal conductivity for metal, combined with good heat capacity. It is cast-iron stoves that can heat up to 3 hours after heating, but they also warm up for at least 40 minutes.

Cast iron on the furnace is 6-25 mm thick. It is impossible to thinner, the stove will be too fragile. But it’s also impossible to get thicker, the temperature coefficient of expansion (TC) of cast iron is quite metallic, and with a “brick” wall thickness, the furnace will crack during heating. Therefore, cast-iron stoves are heavy, you cannot put them directly on the floor, you need to disassemble its flooring to the screed and build it up to the floor level. And the "brick" qualities of a cast-iron stove appear only when heating small, up to 60 cubic meters. m, premises. In large ones, due to the low thermal conductivity of the walls, the efficiency of the furnace will be negligible.

Cast iron does not breathe like brick, but its chemical resistance approaches that of ceramics. Cast iron, like metal, is not afraid of interruptions in the furnace and air dampness. Therefore, it is advisable to use cast-iron stoves for heating utility rooms with delicate small animals: poultry houses, rabbitries, small greenhouses.

Cast iron, as you know, after casting in the factory, is not subject to handicraft machining. All that a do-it-yourselfer with a cast-iron stove can do is paint the purchased. Painting stoves, by the way, is also not an easy job, see below.

Schema and type selection

What is an oven?

Since we are talking about furnaces as such, let's decide what we are dealing with; in the classification of furnaces, there is more confusion than clarity. For example, a fiery channel furnace is considered a furnace with forced circulation of flue gases, and a bell-type furnace is considered a furnace with free circulation. But what freedom does it have for flue gases, if the vault of the cap prevents them from going up, and the same cap, absorbing their heat, makes them descend to the chimney located below in the most unnatural way? The only heating and cooking device with completely free circulation is a fire on the ground.

On the other hand, the definition of "forced" implies the presence of a pressurizer or a smoke exhauster, or both. Finally, the use of heat from the same source in the same device at different times is possible for different purposes. And the source of heat and its transmitter where it should be does not have to be fuel and flue gases.

Therefore, we will define a furnace as a device in which the heat flow from its compact source is directed to the heat energy receiver by technical means within one integral device without the use of separate heat transfer lines. Under this definition, a kitchen wood-burning stove, and a melting electric arc furnace, and a laboratory muffle, and a solar camping stove are suitable.

Domestic ovens

We are interested in household heating and cooking stoves. Let's look at them first in general, and then take into account the features of our material - metal. The main schemes for the construction of household stoves are shown in fig.

chamber

On the left pos. scheme of the oldest furnace as such - chamber. In it, flue gases from the furnace are transferred to the gas chamber, where they burn out, due to natural circulation. Also, in a natural way, outside air leaks to the burning fuel. In essence, this is a fire in a cave.

In modern industrial chamber furnaces, it is difficult even for a specialist to recognize their primitive ancestor, but with domestic ones it is easier, here the furnace with the afterburner is combined into one module - the crucible. For effective afterburning, the chamber must be vaulted. "Primitive" chamber furnaces, with some improvements, can be very effective. An example is surviving to this day.

Drier

On the middle pose. - channel oven. Flue gases, first burning down and then gradually cooling down, pass through the channels between the partitions, giving off heat to the body of the furnace. Perhaps that is why the channel furnace is considered “forced”, the path of gases in it is physically organized. Until such a furnace inside warms up to at least 400 degrees, there is no afterburning at all, and then it stretches from the furnace to the chimney, and it is very difficult to achieve an efficiency of over 60% here.

Kolpakovaya

On the right is a bell-type furnace. The flue gases in it linger under the dome of the hood until they burn out, and then fall down along its walls, giving off the remaining heat. When kindling, it is necessary to warm up only a small section of the bell roof to start afterburning, so a bell-type furnace can provide an efficiency of over 70%

Applied to metal

The ratio of the thermal conductivity of a metal to its heat capacity is ten times higher than that of a brick. Therefore, metal is a lousy heat accumulator. Absorbing it, it quickly heats up to a high temperature, and then cools down just as quickly.

But if we accurately take into account the properties of the material, metal heating furnaces can also be made according to classical schemes, and higher parameters can be achieved from them, because. heat losses for heating the furnace during heating are minimal. And the high connectivity of the metal structure makes it possible to apply the principles of fuel combustion, for brick ovens, either completely unfeasible, or feasible with great difficulty. The main schemes of metal household furnaces are shown in fig.

chamber

Metal chamber furnace - on pos A. Do you recognize it? . Her ancestors, indoor stoves, appeared at the beginning of the 19th century, but were distinguished by their rare voracity; However, the fuel then cost pennies. The devastation after the revolution in Russia forced the "former specialists" to improve the potbelly stove, at the same time it got its name. The following has been improved:

To adjust the power according to the weather, a grate with a blower and its door was built into the crucible.
The chimney was made low, up to 2.5-3 m from the level of the grate.
The diameter of the chimney was taken approximately 7-9 mm per 1 kW of thermal power, in terms of modern units of measurement.
The initial section of the chimney, about 1-1.5 m, was made vertical and wrapped with thermal insulation.
This was followed by a horizontal piece of the chimney - hogs - at least 2.5 m long, it was brought out into the window and increased by a vertical section that also provided traction, also 1-1.5 m.

The role of the arch of the crucible on the minimum firebox was played by the first vertical isolated section of the chimney - a gas economizer, in which flue gases burned out. At the maximum, the throughput of the chimney turned out to be less than the volume of gases generated in the furnace. At the same time, a vortex appeared in the crucible, providing the main afterburning, and the stove became self-regulating: the gases went into the pipe only after they had completely burned out. Heat transfer to the room is approximately 25% provided by the heated body of the furnace and 75% by convection from a red-hot hog. At the outlet of the chimney, the temperature of the gases is above 100 degrees, so condensation (see below) is excluded. Cleaning the chimney from soot is required no more than 1 time per year and is not difficult, since the chimney is collapsible. Furnace efficiency - up to 60% on dry wood or coal.

Drier

It is easy to adapt a potbelly stove to a channel scheme, but the resemblance to a brick channel stove remains only external. Firstly, due to the high thermal conductivity of the metal, there will be no sense from the developed labyrinth of gas ducts, so only one horizontal elbow remains from it. And its role is completely different: the partition separates the afterburning chamber from the furnace. The secondary air required for it enters either through the slots in the burner on the hob, or through a separate air throttle-regulator. The outlet to the chimney is horizontal. These improvements gave the following:

Efficiency due to afterburning concentrated in one place has increased to 70-80%
The volume-specific thermal power of the furnace increased by 2-3 times.
The stove is not critical to the amount of draft and, in general, to the parameters of the chimney, like an ordinary potbelly stove: draft has increased, combustion in the furnace will increase, but also rarefaction in the afterburner. More secondary air will pass into it and the gases will still burn out completely.
Since the main heat is generated in the afterburner, the furnace can operate in both flame and long burning modes.
Heat transfer through a thin metal partition from the furnace to the afterburner immediately ensures the flash point of unburned gases in it, so the furnace enters the mode almost instantly, which further increases its efficiency.
Separate adjustment of the air supply to the furnace and afterburner allows you to adjust the furnace for almost any type of solid fuel.
The power of the furnace can be adjusted not by the amount of fuel loading, but by the air supply. In a potbelly stove, the ability to adjust power with air is very limited, no more than 2-2.5 times.
The temperature of the hob, due to the uniformity of thermochemical processes in the afterburner, is kept within 250-300 degrees, which is quite suitable for cooking.
The high intensity of heat release in the furnace allows you to organize a quick and uniform heating of the room by convection.
At the outlet to the chimney, you can put a DHW heat exchanger without fear of deterioration in the parameters of the furnace and increased soot deposition.
On good wood fuel or coal, cleaning the chimney is required only once every 4-5 years.

Almost all modern heating and cooking household stoves of small (up to 12-15 kW) power are built exactly according to this scheme. When self-manufacturing from heat-resistant steel, you need to make an afterburner, in the form of a trough open on top (partition + side walls). At the same time, ordinary steel from 4 mm will go to the furnace body, and cast iron or steel from 8 mm will go to the hob. The plate must be made removable, especially steel, because. from heat and thermochemistry in the afterburner, it will last a year or two.

long burning

The use of an effective bell scheme in relation to metal made it necessary to abandon the flame: no metal bell can absorb, without overheating, as much heat as it emits. I had to switch the stoves to smoldering mode, which at the same time made it possible to bring the heat transfer time up to 60-72 hours from one load of firewood or up to 20-30 days (!) On coal. Further on, we will dwell on long-burning furnaces in more detail, and a simplified one, without an air supply system and technological hatches, is shown on:

The fuel mass 1 smolders in a thin surface layer 2, and air is supplied here in one way or another.
Pyrolysis, the thermal decomposition of solid fuel into combustible volatile components, plays a significant role in the smoldering process.
The combustion of volatiles occurs in the space under the lid of the furnace ("hood") 3, up to 60% of heat is released here.
If it is necessary to obtain an efficiency of the furnace of more than 70%, it is equipped with a gas jacket 4, here the flue gases burn out in the usual way. The air required for this is sucked in at the pass from the fuel chamber into the gas jacket.

Long-burning furnaces with a simple design can provide an efficiency of up to 80% or more, and the temperature in any of their places rarely exceeds 600 degrees. Therefore, home-made metal furnaces, except for, are mostly performed according to this scheme. Taking into account such a design, you need to consider the following:

Although long-burning stoves operate on any solid fuel from sawdust to coal, they will show the calculated (or verified on an experimental design) parameters only on the fuel for which they are designed. For example, KV on coal is heated like on wood, up to 3 days. A special coal-fired boiler, also of slow burning, on the same amount of coal - up to 20. And it is not capable of working on wood at all.
The products of complete combustion of fossil fuels are carbon dioxide and water, regardless of the degree of its watering; this process is akin to the formation of metabolic water in living organisms. Gases in the chimney of long-burning furnaces go very cold, because. The efficiency of the furnace is high, and the temperature in the furnace is low. Therefore, abundant condensate is formed in the chimney, which is very toxic, and the design of the chimney must contain its collector with the possibility of draining.
Long-burning stoves do not tolerate wet fuel; as you know, the wet does not smolder, no matter how much air is supplied to it.
It is impossible to add fuel to the furnace until the previous load is completely burned out, with one exception, see below. Opening the lid or loading hatch of an unburned furnace is deadly: pyrolysis gases are chemically aggressive and poisonous!

Note: directly above the smoldering zone, the furnace body is red-hot, but this does not prevent its manufacture from ordinary steel. As it burns out, the red-hot belt shifts down and the duration of exposure to the metal of the limiting temperature does not exceed the allowable 3 hours.

The furnace body can be made from any suitable round steel container, e.g. from a barrel. But it is already more difficult to surround it with an airtight gas jacket. In any case, such a stove heats mainly by radiation, which is not very good. The way out is to surround the furnace body, at a distance of 70-80 mm from it, with a hot water hot water register in the form of a coil or an annular tank. Convection will increase and there will be hot water in the shower and in the kitchen. It is only necessary to provide a storage tank with a capacity of approximately 10 l / kW, otherwise the system will boil.

Oil pyrolysis

Such an effective thermochemical process as pyrolysis could not help but receive independent development among do-it-yourselfers who were very willing to experiment. They, as a rule, form some reserves of waste heavy combustible liquids, for example. working off. So the metal pyrolysis was born,.

The oil burns in the tank, where primary air is supplied through the throttle - the power regulator (it is also the filling hole). Combustion is weak, it is only needed to evaporate the fuel. Its vapors rise into the pyrolysis column - a pipe with perforated walls; secondary air passes through the perforations. It enters the mixing zone in excess.

In the pyrolysis zone, the fuel vapor columns burn, but the heat from this is mostly spent on the decomposition of the fuel to light volatile components that burn in the combustion zone; Approximately 35% of useful heat is released here. The other 35%, from the heavy residues escaping pyrolysis, are released in the afterburner.

In the afterburner, there is an incomplete partition, horizontal or vertical, inside. Why is she? In the combustion zone of the column, due to an excess of oxygen, a high temperature, up to 1000 degrees, develops. In this case, endothermic oxides of nitrogen are formed. They are toxic and take a lot of fuel energy to form them.

At temperatures above 700 degrees, nitrogen oxides are stable and in the zone of oxygen afterburning of heavy radicals they will remain as they were. If they are allowed to cool quickly, they will skip the peak of the instability of their phase diagram and fly away into the chimney, taking away the efficiency of the furnace. In order for nitrogen oxides to decompose themselves, releasing the energy spent on them, they must be kept in a zone with a temperature of 450-600 degrees. It is she who is formed behind the partition before exiting the chimney. Why? There is a whirlwind.

Note: No one really measured the efficiency of furnaces during mining. Only the fuel consumption for heating a standard garage 4x7x2.2 m is known. It is 1.5-2.5 l / h.

Sometimes a garage potbelly stove is made with a round blower with a diameter along the outer diameter of the oil stove column and placed on high legs. A tank with a column is left from the oil pyrolysis furnace, and the column itself is made in the form of an arc with a horizontal outlet. Then, as mining accumulates, the potbelly stove is used as an afterburner in a pyrolysis furnace. The exit of the column is inserted into the blower, and the oil potbelly stove is ready. The mining is over - we heat again with firewood / coal.

Note: in principle, it is possible to refuel the furnace during mining, but it is dangerous. In general, these furnaces are an incendiary time bomb with a fuse set for an unknown period. Fire regulations prohibit their use in everyday life and they are not widely sold.

About shielding furnaces

A steel furnace in operation becomes very hot and warms to a large extent with thermal (infrared, IR) radiation. For residential premises, this is undesirable: it swells in the face, and the back freezes. They are preferably heated by convection. In addition, a hot stove can cause severe burns.

How to turn IR into a stream of warm air? Very simple: surround the oven from the sides with a metal sheet screen at a distance of 70-100 mm from the oven and with the same clearance from the floor.

You can meet statements: they say, an iron screen is useless, metal for IR is the same as glass. First, the metal begins to transmit electromagnetic radiation from x-rays and higher in frequency. Secondly, not like window glass, but like milky glass, partially and diffusely. And for IR, any metal is opaque, but diffusely reflects about half of them. In the IR photo, the metal sheet looks light gray.

Assume that an IR flux of unit power falls from the furnace onto the screen. 0.5 of it will be reflected back, and the remaining 0.5 will be radiated by the screen in both directions, back and out. In total, only a quarter will come out. This is a rough scheme, if the screen becomes very hot and its temperature approaches the furnace temperature, the proportion of external radiation increases; up to 1 at equal temperatures.

When calculating the screen, it must be coordinated with the heat capacity and viscosity of the air so that the heat between the screen and the furnace gives rise to intense convection, which cools the screen. With the dimensions indicated above, the external temperature of the screen will not exceed 70 degrees and the heat transfer by convection will be at least 85% of the heat output of the furnace.

Note: it is better to make the screen sliding in breadth, in the form of 2 L-shaped halves, and on separate legs. Then, by pushing / moving the sidewalls, you can adjust the gap between it and the furnace in accordance with the furnace mode.

It will be bad to shield the internal partition in the furnace, because. temperatures in the furnace and afterburner are close. But radiation upwards from the hob is not dangerous and does not suppress convection. It is simply impossible to shield from the front: there are doors and an approach to the furnace. It remains to decide what to do with the radiation down from the bottom of the furnace, there is nothing for him to heat the flammable floor in vain.

This problem is also solved without much difficulty: we deepen the ash pan down from the blower door and lay it out on a dry, without mortar, brick. You can fill it with brick battle or sand, but then when you excavate the ash, you will have to rake and throw away the backfill. If we bring all these methods into one, we get the shielding scheme shown in Fig. higher.

Shielding for a bath

Specific, per unit volume of the room, the power of bath stoves is 3-5 times higher than that of room stoves, and the walls of a normal bath are wooden, poorly conducting heat. Therefore, a quick heating of the bath can be provided only by convection, on the one hand. On the other hand, a metal sauna stove gives too hard heat for the same reason that it does not breathe. Based on this, we make a brick screen for the bath; enough laying in half a brick for. It is only necessary to lay out the first row at intervals to ensure convection, as shown in fig. on right.

Shielding for giving

The country house is also small, it is empty in winter and it is not necessary to heat it to the bath temperature. Therefore, a country stove can, in principle, be screened like a bathhouse. But it’s better not to be too lazy, install a hot water storage tank in the attic, and surround the stove for giving, like a screen, with its water heater, see fig. left. Water absorbs IR completely, and while people stretch their hands frozen in the garden to the stove, and then gobble up sandwiches, a kettle will boil on the hob, and enough water will accumulate in the tank for a shower.

Note: shielding the hearth of the oven from the inside with heat-intensive material gives an additional advantage here - you can put shoes under the oven to dry without fear that it will dry out and crack.

The development of the idea of a screen-convector was the appearance of stoves-heaters. They are initially designed so that as much of the heat as possible is converted into the energy of the movement of the heated air flow. To do this, the convector is built into the furnace or a precisely calculated screen is made along with the body of the furnace.

The most famous model of this kind - or simply a buller (left and middle pos. in the figure). In the Russian Federation, bullers are produced under a license under the Breneran brand. Buller features are as follows:

Buleryan - exceptionally long burning. The flame mode is an emergency for her, and all attempts to adapt bullers to any other type of fuel have so far been unsuccessful.
Fuel-mode fastidiousness allowed air to be supplied to the furnace through one throttle. Air enters the afterburner partly mixed with flue gases, partly through a perforated partition between the furnace and the afterburner.
A well-thought-out design and an optimal configuration of the entire furnace allow for power adjustment over a wide range, by 10-12 times.
The firebox, rounded in section, and the convector built into it 2/3 deep from the tube batteries provide powerful convection (6 cubic meters / min per 1 kW of firebox power) without a significant deterioration in the efficiency of the furnace.
The temperature of the air leaving the batteries and the outer surface of the furnace does not exceed 70 degrees.
When the power is reduced by the throttle, the temperature of the outgoing air drops faster than its flow, i.e. at lower power, the buller heats up just as quickly, but weaker.

The duration of heat transfer of buleryan with one full load of fuel is 8-12 hours. Serial bullers are produced for a power of 10-200 kW. The efficiency of the buller is about 60% By surrounding the stove with a screen, it can be increased to 66-67%, while the temperature of the outer surface of the screen will be about 55 degrees. The temperature inside the buller never exceeds 600 degrees, so it is quite possible to make it yourself from ordinary steel, but you can’t do it from the tip.

Buller's secret is in the exact internal balance of heat and air. To take away too little heat for convection - the stove will give little hot, overdried air. Take away a lot - the fuel will not burn out properly, a lot of ash, soot is formed, the efficiency of the furnace will drop. It is the same with air: the configuration and size ratio of all furnace parts provide automatic redistribution of air flows inside according to the combustion mode. But a step to the right, a step to the left - again ash, soot, gluttony and little heat.

Therefore, it is better not to try to calculate the buller yourself, guided by the initial information about heat engineering. It is possible to replicate a proven design, but with precise dimensions, instructions, and specifications. The length and configuration of the chimney is not critical, but a condensate collector is necessary in it, because. flue gas temperature is low.

Bullers are usually used for heating industrial premises that require uniform heating to a comfortable or process temperature: greenhouses, conservatories, nurseries of heat-loving animals. However, by installing a buller of suitable power in the basement, it is possible to provide air heating for a private house of almost any area: a large number of convector nozzles (from 7 to 23-25) allows you to organize a uniform distribution of heat throughout the rooms. The nozzles of the furnace batteries are simply mated with air ducts made of cheap thin-walled corrugation, and it is easier and cheaper to arrange an air duct system in the house than to mount pipes and water heating registers. In addition, there is no need for complex, expensive, energy-intensive and maintenance-intensive water boiler piping.

In Russia, a lot of similar designs budded from the buller; one of the most famous is the Professor Butakov line of stoves, right pos. in fig. The Butakovs are multi-fuel, their efficiency is higher than that of a buller, they have a hob, but here, in an article for home-made people, it is worth mentioning them only in passing: the construction of special steel is designed exclusively for industrial production. In addition, the Butakovs can heat only 1 room well: it is very difficult to connect air ducts to the outlet of their batteries.

About air heating

Air heating is optimal for individual houses with 1-2 floors. The number of storeys of the house is rapidly devouring its efficiency, so it went out of use even in cramped medieval cities, although rich estates in ancient times were heated with air.

In fact, its wide introduction into the private sector is hindered only by the lack of legal norms, rules, recommendations and methods of engineering calculation. However, for do-it-yourselfers with a vein of an experimenter, this is a plus: since it is not prohibited, then it is possible, as long as the buller itself is certified. Do as you want and know how, without fear of sanctions: why punish if it is not in the law at all?

Slow homemade

If there are no parts in the potbelly stove and its relatives, the rough or careless manufacture of which would completely ruin the stove, then buller already gives an example that you need to be more careful with long-burning stoves. They have nodes, a small mistake in the execution of which will make the oven not only bad, but also dangerous. Therefore, we will dwell on slow-burning stoves in more detail; 2 popular and 1 promising designs are shown in fig.

Pos. A - the famous bubafonya, homemade based on the Latvian slate boiler Stropuva. It belongs to furnaces with a closed smoldering zone, therefore its efficiency is under 70%, and with a gas jacket over 75%. Air through the oppression-"pancake" is supplied to the center of the combustion zone. The increased efficiency is due to the fact that the pyrolysis gases burn out even under pressure, so it must be either made of special steel or thick, 8-12 mm. The second feature, as a result of closed combustion, is that bubafonya, in extreme cases, can be reloaded on the go. The stench shibanet, but you will not be poisoned.

The specific power of bubafoni is about 0.3 kW per 1 cubic meter. dm of fuel, which is not bad. But the fuel itself is sawdust, shavings, small combustible debris, and dry. On wood and coal, the efficiency drops sharply: the duration of heat transfer remains the same, 6-8, up to 12 hours. You can “feed” bubafonya with high-quality high-energy fuel if you are not too lazy and make a “pancake” with curved profiled blades. This will also increase the possibility of reloading: turning the oppression when lifting / lowering will not bring down the combustion and re-ignition of the furnace is not required.

At pos. B1-B3 no less popular open burning stove "Slobozhanka". Its design is elementary, it is not critical to the size and proportions, from the pot to the barrel. The furnace can operate on waste fuel, wood, coal, tropho briquettes. 3 circumstances prevent "Slobozhanka" from competing in bubafonei:

Additional loading on the go is impossible, removing the lid in an unburned furnace is deadly.
Due to open combustion, the specific thermal power is 2-3 times lower than in furnaces with a closed combustion zone.
An air distribution shaft made of ordinary steel with a thickness of 6 mm with regular intensive combustion burns out before the end of the heating season, and a body made of 3 mm steel lasts 2-3 years due to active chemical corrosion in the gas cushion.

It is possible to increase the durability and specific power of the Slobozhanka by making the fire body of special steel. Air distributors are made several directly in the walls of the housing (its development is at pos. B2). But then you have to surround the oven with an air jacket with partitions, and even make an annular blower, pos. B3. For a do-it-yourselfer, such a design is too complicated, and unprofitable in production. Therefore, "Slobozhanka" is produced only in small batches by small firms, and they are in some demand only in the southern regions as stoves for occasional heating of utility rooms.

Note: for furnaces with a gas jacket, the condensate collector will have to be buried in the floor, and the accumulated pump out, because. in furnaces with a gas jacket, the outlet to the chimney is lower.

At pos. B - scheme of the furnace, once produced by the Soviet military industry for heating the barracks of small remote garrisons. Possessed high specific power; a stove the size of a barrel heated a room of 150-160 sq. m. with a ceiling of 4 m. It is omnivorous, everything burned in it, from Suchansky anthracite to fresh household waste. Reloading - on the go without restrictions: a fungus on the air duct / air distributor did not allow a fresh portion of fuel to bury the smoldering zone, and completely burnt gases escaped through the mass of fuel. Only a perforated cone was made of heat-resistant steel, with a seam connection.

Now this furnace seems to be forgotten. The probable reason is the bulkiness and unaesthetic nature of the whole system. In addition to the furnace, its standard equipment included 3 sections of 2 m gas-air heat exchange registers, each in the form of a finned bundle of 5 two-inch thin-walled pipes. Attempts to replace them with a bourgeois chimney led to the fact that the hog heated up to orange, and the stove began to "spit" gas from under the lid.

Installation of a metal furnace

Before taking on any stove, you need to decide on the place of its installation. The first rule in this case, if the oven is convection, it can be placed anywhere. If the stove heats mainly by radiation, it must be placed away from the outer walls, otherwise the rising temperature gradient between the room and the street will lead to large heat losses and eat up a good share of the efficiency of the stove.

Next, we estimate the weight of the furnace per unit area of its projection on the floor. If the weight load does not exceed 150 kg / sq. m, then everything is OK, the stove can be placed directly on the floor. If the load is within 150-400 kg/sq. m, the flooring will have to be dismantled and put the stove on the screed. Installation of metal furnaces, as a rule, does not require parsing the flooring and foundation. In utility rooms with earthen or any other floor without a screed, a reinforced concrete slab with a thickness of at least 7 cm must be placed under the stove. The removal of the slab beyond the contour of the projection of the stove is at least 0.6 m in all directions.

The stove must be at least 0.6 m away from concrete walls or covered with refractory plaster on vermiculite. At least 0.8 m from ordinary plastered walls without wallpaper. If any decorative wall decoration is combustible or can decompose when heated (paint , plastic, wallpaper), the stove must not be moved closer than 1.2 m to it. The use of stationary metal stoves for heating wooden buildings is allowed by fire safety rules in exceptional cases with special permission.

Now, if the stove is a factory one and a chimney is provided in the house, it remains to put heat and fire insulation (see below), connect the stove to the chimney and, without making the slightest fire, call the fire inspector for examination. As a rule, it is limited to small remarks, and after payment of state fees, permission to operate the furnace is issued. The whole procedure will cost about $150 and about a month of time.

If there is no chimney, it must be made and legalized by firefighters and SES separately, before installing the stove. In the case of a branded purchased stove, this is easier: the specifications for a good stove must also be accompanied by specifications for the chimney. Having fulfilled it according to the requirements, you can safely go to the firefighters: after examination and payment of what follows to the treasury, the necessary papers will be issued. Things are worse with the “left” chimney; an approved project is needed for its construction. They will consult free of charge where to order it and what should be in it at the local branch of the VNII PO (VNII Fire Protection Ministry of Emergencies). The bad thing here is that there are branches or departments of VNII PO only in fairly large cities (from 150 thousand approximately), and they do not provide online consultations.

And it turns out really badly if the stove is completely homemade: in order to legalize it, it will first have to be certified in the same VNII PO. Moreover, with long-burning furnaces, any on liquid fuel and gas, you can not go there: they are certified only by the factory ones. There is no law on punishment for home-made stoves, so they won’t be fined for the “left” one. But, if the property is insured, then the mere presence of such a stove, even if it is cold lying far away in the closet, makes the case not insured. And if some “suddenly something” caused damage to the neighbors, it is better to immediately pay off amicably, there will be nothing to cover in court.

Finally, if all these vicissitudes are passed, we put insulation: at least 4 mm of asbestos or basalt cardboard, and on it a sheet of iron with a thickness of 1.5 mm. Removal of insulation from the furnace contour at least 50 mm on the sides and rear and at least 300 mm in front of the furnace. If the furnace is shielded, the offset is calculated from the contour of the shield. Now to the firefighters, as already mentioned, and, after the elimination of the shortcomings indicated by the inspector and the issuance of a permit, you can drown.

Sample drawings

Generally speaking, it is easier to buy a room potbelly stove and a buller. Therefore, for example, we give drawings of 2 popular designs: a small bath potbelly stove, 40-50 cubic meters. m of premises, with a water heater, and a garage furnace for testing. For a potbelly stove, a steel or aluminum storage water tank from 100 liters without thermal insulation is needed, and for an oil stove - a chimney from 4.5 m in height with a condensate collector. The material both there and there is ordinary 4 mm steel.

Video: an example of self-made metal sauna stove

About fireplace stoves

For a fireplace stove, aesthetics are more important than heat engineering. With regard to metal, it is best to buy a ready-made fireplace insert, and apply creativity in design terms. On sale there are special fireplace cassettes, or fireplace cassettes, see fig. on right. They differ from a conventional firebox with a built-in smoke box and an afterburner. The fireplace cassette is more expensive than a simple firebox, but it pays off with simplified requirements for the chimney, and the fins on the afterburner allow you to arrange air heating of the room. You can embed a fireplace cassette anywhere, its outer surface heats up no higher than 70 degrees. Registration in the Ministry of Emergency Situations is not required.

How to paint the oven?

Bare metal looks bad even in a garage or barn and is more prone to corrosion than painted metal. But ordinary paint for the oven will not work, it holds no more than 140-160 degrees. So, how to paint a metal stove?

Silicone and organosilicate enamels are suitable for painting hot surfaces. Who knows that silicon in Latin is silicium, do not be surprised. In organosilicon compounds, hydrogen atoms (and not carbon, as is often incorrectly thought) are partially or completely replaced by silicon. And in organosilicates, the silicon-containing filler is mixed with an organic binder, which evaporates upon drying.

Organosilicon enamels are heat-resistant up to 800 degrees Celsius for 5-12 hours, but are more expensive than organosilicate ones, about 180 rubles / kg versus 150. The heat resistance of organosilicates is 250-350 degrees. Taking into account the fact that the consumption per unit area of organosilicon is higher, and it is heavier, the cost of the finished coating is approximately twice as high. According to the UP-1 instrument, organosilicates are also about twice as strong as organosilicons for chipping.

Based on this, actually it is better to paint the oven with organosilicon, and its screen with organosilicates. In terms of chemical resistance, they are equivalent. The quality and price of foreign and domestic manufacturers differ little. Of the domestic ones, Certa and KO-828 have proven themselves well; from foreign ones - Norwegian Jotun.

How to paint

Heat-resistant enamels for metal are applied only on a clean, fat-free surface from a spray gun in a warm, dry room. Do not paint with a brush or roller. Apply necessarily in 2 layers; the second after the complete drying of the previous one. According to the specifications on enamels, they can also be applied in sea fog at sub-zero temperatures, but only in an electrostatic field using special equipment. Up to the 3rd degree (without a noticeable tack), the enamels dry out in 20 minutes - 3 hours, but for full readiness to keep the heat, the product must be kept for at least 7 days. It is unacceptable to speed up drying with a hair dryer or a stove, the coating will peel off.

Where to begin?

So which stove is better to make first? No doubt - to room potbelly stove with afterburner and hob. If electricity suddenly disappears, gas or coal runs out, and there will be no delivery, she will always help out. At home, it does not take up much space in the pantry, but in the country it can be stationary. Then, as needed, the same potbelly stove without much difficulty will acquire improvements.

As for seemingly simple long-burning furnaces, they are highly efficient precisely because their heat engineering and thermochemistry are very complex. It should be taken for a long-heating stove only after gaining experience.

Conclusion: where metal is good

In everyday life, metal stoves are used more as alternative emergency sources of heat. The second extensive area of their application is the periodic heating of utility and utility rooms, incl. country houses. For continuous heating of industrial premises, heaters are optimal.

(1 ratings, average: 5,00 out of 5)

To create a heating unit in your house, it is not at all necessary to build bulky brick structures or buy expensive appliances. To do this, you can use improvised materials and containers. When building a metal furnace with your own hands, skills in working with a welding machine and an angle grinder will come in handy.

Pros and cons of metal furnaces

The metal stove is a compact heating unit with a one-piece design. Such a furnace can be easily moved, unlike brick options. Its shape may be different. Typically, these structures are made in the form of a cube, parallelepiped or cylinder.

The efficiency of a metal stove is low - it can effectively heat only small rooms ranging from 10 to 30 m². In this regard, such heat sources have become popular among summer residents and pet owners. Such stoves are used to heat country houses, utility rooms, workshops, sheds, garages, chicken coops and other premises with a small area.

It should be noted that metal furnaces are fire hazardous structures. Therefore, you can not leave them unattended for a long time.

Despite the fact that metal stoves are a convenient option and an alternative to capital heating facilities, they also have positive and negative qualities.

Table: advantages and disadvantages of metal furnaces

Advantages

disadvantages

metal construction has great strength;
this material is easy to give any shape;
the cost of a metal furnace is much lower than brick options;
the efficiency of a heating structure made of metal is 15–20% higher than that of brick structures;
the metal unit has a one-piece structure that is easy to move, which cannot be said about stationary heating structures;
metal furnaces do not require foundation installation;
this design heats up quickly and gives off heat to the room after 25–30 minutes;
the metal has a dense and non-porous structure, due to which the furnace will not become damp from condensate, unlike brick structures;
the metal unit is not afraid of long breaks in the furnace;
in the event of a long downtime, the furnace does not need thermal acceleration;
for this type of stoves, it is easier to obtain quality certificates and a fire service permit, which eliminates large financial costs;
today, designs that do not require any special permits for use are on sale;
if you use a furnace made of refractory steel, then its service life reaches 20 years;
affordable price;
The design is easy to install, after which it can be used immediately.

the absence of porosity in the structure of the furnace material leads to the fact that the design “does not breathe”, burning out oxygen in the room, which causes the danger of carbon monoxide poisoning;
despite the rapid heating, the metal furnace cools down quickly;
the outer surfaces of metal furnaces are heated red-hot, creating a fire hazard;
in comparison with a brick structure, a metal furnace has a very short service life;
a metal stove is not intended for heating large rooms.

Types, principle of operation and choice of design for self-production

It should be noted that home-made metal stoves are most often designed with hobs. Therefore, when listing the types of metal furnaces, it is necessary to take into account such designs. There are the following types:

Heating. These units are designed for space heating only. Such furnaces do not perform any other functions.
Heating stoves with hob. These designs provide a surface for cooking. Some buildings of this type are equipped with a stove and oven.
Household. Structures used not only in housing, but also in outbuildings, utility rooms, garages. Such stoves are often installed to heat rooms that contain pets and birds.

According to their structure, metal furnaces are classified into chamber, channel and bell-shaped:

Chamber structures. In such units, flue gases enter a special compartment, in which they are completely burned out under the influence of the natural circulation of gas flows. In domestic buildings, the furnace area is connected to the afterburner, forming a common module called a crucible. For the efficiency of this process, a vaulted shape of the furnace is necessary. A striking example of this is the classic construction of the Russian stove.
Channel structures. In this furnace, the flue gases burn out almost completely, after which they move between the partitions through special channels, in which they gradually cool down. During movement, hot streams give off heat to the walls of the structure. The afterburning of gases in this type of furnace does not occur until the temperature in the combustion channel rises to 400 ° C. The efficiency of this type of furnace does not exceed 60%.
Bell structures. The frame of this unit resembles a cap. Hot streams are directed under the upper part of the furnace (hood) and linger there, completely burning out and heating the entire body. Then the gases go down. To heat up this furnace, it is enough to increase the temperature in a small area of the hood. This feature increases the efficiency of the furnace up to 75%.

For the manufacture of furnaces, steel, cast iron and aluminum are most often used.

aluminum

This option is often used due to the availability of the material, namely aluminum cans. According to its design, this tank is suitable for creating a heating unit. It is only necessary to make a hole at its base for installing a chimney. However, the melting point of aluminum is 660°C.

This parameter makes the material unstable to strong heat. This is due to the fact that high efficiency is achieved as a result of afterburning of exhaust flue gases. During this process, the temperature is about 400°C.

If it is planned to produce an ecological oven, then the heating will reach 600 ° C.

Given the indicated temperature limits, aluminum is not the best material for making a stove. The walls of the unit will quickly burn out, and the design of the can will soon deform.

Of steel

The melting temperature of steel is in the range from 1450 to 1520 ° C, so this material, in comparison with the previous one, is more suitable for the manufacture of such structures.

It should be noted that to create a heating unit, it is necessary to use sheets of at least 4 mm in thickness.

This is due to the fact that every metal, regardless of its type, burns out under the influence of high temperatures. Therefore, the use of thinner material is impractical. The thin walls of the oven, subject to constant use, will burn out in 3-4 months.

To increase the resistance of the material to high temperatures and extend the life of the heating structure, it can be hardened. To do this, the steel sheets are red-hot.

It is necessary to ensure that black or blue spots do not appear on the metal. This will indicate an incorrect hardening. You should also take into account the temperature of the hearth, in which the coals should not be heated to white.

If you place the metal in such conditions, it will quickly burn out.

To determine the combustion temperature, it is necessary to use the heating scale.

In the process of hardening the metal, it will be necessary to place it in engine oil and in warm water. Cooled steel sheets under the influence of high temperatures can be deformed, acquiring a wavy surface. To correct this defect, the steel sheet is leveled with a hammer. The metal hardening process can be carried out several times.

To check the quality of steel hardening, it is necessary to use a file, the working part of which is carried out along the edge of the steel sheet. If the file sticks to the metal, then this indicates its insufficient hardening.

If it is not possible to deal with metal hardening, refractory steel can be used. Depending on the alloys it contains, the required melting point reaches 2500°C.

This makes it possible to use material with a thickness ranging from 1.5 to 3 mm. A refractory steel furnace with the specified wall thickness can last up to 30 years. The entire structure will be smaller than a similarly sized ordinary steel furnace, and the efficiency is much higher. A striking example is the Slobozhanka oven.

from cast iron

The melting point of cast iron is 1450 degrees. This material is often used for the manufacture of radiators in apartments and houses. It combines the properties of metal and brick. Because of this, cast iron is a very heavy and brittle material.

Cast iron has a low thermal conductivity - it retains heat well inside the furnace. In addition, the metal heats up quickly, and after the furnace is completed, it continues to give off heat for 3–4 hours.

To make a furnace, it is necessary to use cast iron with a thickness of 6 to 25 mm. If the furnace walls are less than 6 mm, then the structure will be very fragile. If they are more than 25 mm, then at the first firebox the furnace body may crack. Since the whole structure will have a lot of weight, it requires the installation of a solid foundation. For this, a slab foundation is made.

Furnaces made of this material are effective for heating small rooms, the area of \u200b\u200bwhich does not exceed 60 m².

Cast iron is not suitable for the independent manufacture of such a furnace, since it is difficult to process in home workshops.

Possible designs and their features

Metal furnaces are made of closed, open and combined designs.

closed design

Such a furnace, as a rule, includes three compartments:

the lower one, in which there is a combustion chamber with a blower;
middle, which includes a heater and a steam outlet;
top, which is a tank for heating water.

Furnaces of this type are lined inside and outside with refractory bricks. This contributes to an increase in the heat capacity of the unit. To speed up the heating process, the tank and the steam outlet are closed with a special damper. To warm up a room with a volume of 10–12 m³, it takes from 60 to 100 minutes.

Open design

Unlike the previous type, the stones are placed on a metal grate located above the combustion chamber. There is no overlap between the furnace and stones. As in the first case, these stoves are designed for use in small baths and steam rooms. To increase the heat capacity, a lid made of galvanized sheet is used, which is used to cover the stones.

Combined type of ovens

A distinctive feature of the design of this type of furnace is the presence of an enlarged combustion chamber equipped with double valves and grates. The presence of two pairs of such elements in the design contributes to the efficient operation of the blower and heater. In the upper part of the unit, in its neck, stones are placed. These elements are wrapped around the chimney.

Calculation of the main parameters

For manufacturing, a metal stove-heater of a closed type was chosen.

Its base will be square, 600x600 mm in size. The height of the structure will be 1350 mm. The height of the furnace part is 653 mm, the chimney pipe is 600 mm. For the chimney channel, a pipe with a cross section of 150 mm is required.

To calculate the approximate heat transfer of this furnace, it is necessary to multiply the cubic capacity of the heated room by the value - 21. Let's say that the room has dimensions: length - 3 m, width -2.5 m, height - 2.3 m. For example, it will look like this: 2∙2.5∙2.3=11.5 m³ is the volume of the room. Now we calculate the required heat transfer of the furnace for a room of the specified size: 11.5 ∙ 21 \u003d 241.5 kcal / h.

Necessary materials and tools

In the manufacture and installation of a metal furnace, the following tools will be required:

Shovel and bayonet shovel.
A hammer.
Pick.
Tanks for water, concrete mortar and masonry mixture.
Concrete mixer.
Building level.
Yardstick.
Big square.
Plumb.
Welding machine.
Angle grinder.
File.
Cord.

You will also need the following materials:

Concrete mix brand M 300 or M 400.
Reinforcing bars for the manufacture of a reinforcing lattice for the foundation.
Waterproofing material - roofing material or thick polyethylene.
Masonry mix or clay.
Asbestos cord.
Stones (dunite, jadeite, quartzite, jade, soapstone, chromite)
For the manufacture of a furnace structure from steel sheets, you will need:

1 sheet 3 mm thick, 60x60 cm in size;
4 sheets, 3 mm each - 100x60 cm;
1 sheet for the grate - 60x60 cm, 12 mm thick;
1 sheet for the partition of the combustion chamber - 60x60 cm, 3 mm thick;
pipe with a section of 150 mm, with a wall thickness of 8 mm;
4 corners 10 cm long, with a margin width of 5 cm.

Preparatory work: choosing the installation site and laying the foundation

Cut parts from steel sheets must be checked for the absence of burrs and sharp metal protrusions, as they will interfere during welding. You should also pay attention to the dimensions of the cut out elements.

When choosing a place to install the stove, it should be noted that these units are best installed in the corner of the room away from the walk-through doors and windows. If such a stove is intended for a bath or a steam room, then it can be installed behind a small partition. This will additionally protect against accidental contact with the hot surfaces of the oven.

It is best to build the foundation for the furnace along with the building under construction. However, if the heating structure is planned to be installed indoors, it is necessary to disassemble the floor to the very foundation. In this case, the logs can be sawn only after the foundation has been erected to their level.

It should be noted that the foundations of the house and the furnace should not be connected.

Over time, the building shrinks, and otherwise the base of the furnace will crack, and the unit will warp.

To lay the foundation for a brick-lined oven, you must perform the following steps:

Make a marking of the future dimensions of the furnace. It is more convenient to take notes on the wall.
Dismantle the flooring. You need to get to the ground. At this stage, do not cut the wooden logs.
In accordance with the markings on the wall, dig a pit 50 cm deep and 75 cm wide. If there is a large amount of sand in the soil, then the walls of the pit may crumble. To avoid this, it is necessary to cover them with roofing material or polyethylene.
The bottom of the pit is carefully compacted and leveled.
Pour gravel of medium fraction inside to make a layer 250 mm thick.
Lay waterproofing on top of it - roofing material.
Then fill up a layer of sand equal to 150 mm. It needs to be tamped down. It should be noted that wet sand compresses better.
From boards or OSB slabs, make formwork for liquid concrete. If it is made of boards, then concrete can pour out through the cracks or earth can fall inside. To prevent this, the inner surface of the formwork can be covered with polyethylene.
Now you need to make a metal frame that will strengthen the concrete base. This requires reinforcing bars with a thickness of 8 to 10 mm. Of these, it is required to make a three-dimensional structure consisting of two gratings connected at a distance of 200 mm parallel to each other. The width of the cells should be no more than 150x150 mm. The intersections of the reinforcing bars can be strengthened by welding, wire or plastic clamps.
Install the finished metal frame inside the formwork. It should be noted that this structure must be placed at a height of 50 mm above the waterproofing. To do this, you can, perpendicular to the base, drive in wooden stakes or pieces of reinforcement. Attach a metal frame to them. You can use halves of bricks for this, which will create the desired height for placement.
Pour concrete mix. For this, the M 300 or M 400 brand is suitable. It should be noted that all elements of the reinforcing cage are hidden under a layer of concrete. In the process of pouring the foundation, air bubbles are formed, which must be removed by baying or using a deep vibrator.
Cover the poured mixture with polyethylene. This is necessary for uniform hardening of the foundation. If this is not done, moisture will evaporate from the top layer of concrete. This can cause the hardened base to crack and lose its strength. After 8-10 days, the foundation will harden.
Clear the hardened base from dust and debris.
Cover with waterproofing material. For this, roofing material or thick polyethylene is suitable.
From above, in a continuous layer, make masonry of refractory red brick. When the masonry level reaches the lag, they must be sawn so that the wooden ends lie on a concrete base.

Do-it-yourself step-by-step instructions for making a metal furnace with your own hands

A metal furnace can be made not only from steel sheets, but also using improvised materials. If everything is clear with steel structures, then an old bathtub can be used as a cast-iron frame. Below is a variant of the manufacture of a stove-heater from steel sheets.

Production of a stove-heater

In a steel sheet 12 mm thick, cut parallel strips, 8 mm wide. This structural element will play the role of grate.
Using welding, connect steel sheets according to the diagram.
Weld a pipe with a diameter of 150 mm.
Weld a steel door measuring 350x200 mm to the finished furnace body, which will close the combustion chamber.
Weld a door measuring 150x100 mm to the blower hole.
Use an angle grinder to remove burrs and sharp fragments from the surface of the furnace body.
Weld steel corners to each corner of the bottom of the furnace, with a margin of 50 mm. The whole structure will stand on these elements.
Install the structure on the prepared base.
Now the oven must be overlaid with bricks. To do this, the building material must be soaked in water for 30 minutes. After that, make a markup for masonry. During masonry, the furnace body may become soiled with mortar. Therefore, it is advisable to cover the metal structure with a plastic film. It should be noted that the brick structure must be erected at a distance of at least 10 cm from the wall, and the surfaces of adjacent walls must be covered with sheet metal or refractory tiles. This is for fire safety purposes.
Laying starts from the marking corner. Bricks should be laid flat. The seams between them should be the same, no more than 5 mm.
Between the first and second row it is necessary to lay a reinforcing mesh. To do this, it is cut into strips and stacked. This element will strengthen the brick structure.
In the third row of masonry, it is necessary to leave two gaps for holes. This will help normal air circulation.
Lay out the next rows with dressing.
The lining of the combustion chamber must be laid out with fireclay bricks. This material withstands high temperatures without changing its structure.
During laying, blower doors and valves are installed in the lower and upper rows. These elements are designed to regulate draft, overlap and direct hot flows.
A heating shield can be provided in the design of the brick lining of the furnace. The diagram shows the stages of the construction of rows.

Chimney device, its manufacture and installation

The order of the chimney has its own characteristics. At the junction of the chimney pipe with the roof there is an extension of the masonry. From the outside, this protrusion protects the structure from atmospheric precipitation, from the inside it reduces the temperature of the outlet stream. The diagram shows the ordering of the chimney for a metal stove.

Decor

You can decorate the oven in various ways:

Plastering.
Finishing with facing bricks.
Tiles.
Various types of tiles (terracotta, majolica, clinker).
Natural and artificial stone.
Marble.
metal.

Finishing the furnace with metal is the simplest and most effective way. For this, sheet steel or rolled aluminum is used. The end surfaces of the furnace, coated with these materials, create an additional insulating layer.

Silicone paints of various shades are used for coloring metal.

Operation features: cleaning and repair of the stove

The operation of a brick-lined stove must comply with the following rules:

Before each use of the heating unit, the presence of draft must be checked. To do this, move the metal valve. The absence of draft or its movement in the opposite direction will indicate clogging of the grate or the entire chimney channel.
To minimize the amount of soot masses formed during the combustion of firewood, it is necessary to use wood of certain species. Aspen, oak, birch and beech firewood are suitable for this.
For kindling, it is best to use softwood shavings, as this material contains resins that flare up quickly. For this purpose, it is convenient to use pine and spruce cones.
With the constant use of a metal stove, it is necessary to take care of cleaning the chimney from soot every heating season. If the oven is used several times a month, this procedure is performed once every 2-3 years.
Efficient burning of firewood occurs only when the combustion chamber is loaded by 1/3.
In the event of cracks in the brickwork, they are sealed with a special clay blue rock or special mixtures for laying stoves. You can heat the oven only after the clay has dried.

Having studied the nuances of manufacturing a metal furnace, you will not only be able to make a high-quality heating unit yourself, but also successfully use it for heating domestic and utility rooms.

A metal stove for a summer residence is made much easier and faster than its bulkier brick counterpart.

Required to build less time, expensive materials and experience, which the person who took up this occupation is trained.

The design easily includes a heat exchanger, hob or oven.

Types of metal wood-burning stoves for summer cottages

Exist several varieties furnaces in which the role of the main building element is played by metal. Each described scheme has positive and negative sides.

Ordinary iron

An ordinary metal furnace, the operational features of which are fully determined by the main building material. Iron poorly accumulates heat and has a high thermal conductivity.

Such an oven is located on a specially prepared site to exclude any contact with wooden elements.

Thus, they prevent possible ignition, which occurs when the external surfaces are excessively heated.

The feature described gives Benefits. There is a way to build a furnace that has high performance with minimal heating. This is due to the fact that during the service of such a product it becomes possible to use the principles of fuel combustion that do not work when it comes to a stove made of bricks. This is achieved by wisely using a high degree of connectivity metal structural elements.

Width metal furnace reaches 600 mm, length equals 600 mm, height taking into account the chimney pipe reaches 1350 mm.

Metal stove

The metal stove-fireplace for giving has interesting useful features. The furnace is made in the form of a chamber, and is located on a special stand or support. Thereby, there is no need to mount an additional foundation for such a building.

A solid foundation is essential due to the hefty mass of the steel fireplace. The device of such an oven harmoniously fits into the interior country house or cottage. A pipe is connected to the furnace, designed to remove smoky masses, which can effectively remove combustion products from the system.

To prevent accidental ignition, the surface of the stove - fireplace lined with refractory materials.

Such a device has high efficiency, does not require special personal care, unpretentious during installation, which is done in a few minutes. Fireplace capable heat up instantly room and installed anywhere.

AT width reaches 1300 mm, height comes to 2500 mm and length leveling 1200 mm.

Making a country stove with your own hands

To assemble without delay and difficulty, you need the following.

Project

If you need to heat garage or other secondary premises, then preference is given to an ordinary metal furnace.

It's easy to make and heats up fairly quickly. At the same time, the unit does not require much fuel and refers to a variety of relatively economical home-made heaters. The owner does not have to spend too much on firewood to keep warm.

If you want to install such a structure inside private house or cottage, a fireplace stove is considered the best choice. She possesses less fire hazard with fire resistant lining. The product is able to quickly heat up and heat the room. The oven is characterized aesthetic appearance harmoniously fitting into the interior.

materials

It is necessary to select raw materials for construction. As mentioned above, the role of the main building material is played by metal sheets with a thickness of 5 mm. A similar condition is met to avoid burnout of the walls during operation of the furnace.

For the arrangement of the foundation you will need cement mortar and refractory bricks. The legs of the oven require corners made of metal, the thickness of which is not less than 8-10 mm.

Harvested pipe for chimney diameter from 10 cm and of sufficient length to ensure the exit of smoky masses outside the room.

A special platform is made in front of the firebox door, designed to increase fire safety. For the organization which is being prepared metal sheet with a thickness of 3 mm.

High-quality materials will allow the unit to serve for a long time and properly heat the room. When choosing a metal preference is given to the thickest sheets, as the oven tends to heat up quickly.

Place for construction

To prepare a place for the stove, as mentioned above, it is necessary to limit the contact of the heating elements of the structure with the wooden interior parts.

To prevent accidental ignition at the location of the structure, small foundation, on which the furnace itself will be installed in the future. For the construction, refractory bricks and high-quality cement are selected.

Important! If you correctly follow the described preliminary procedures, then the oven will turn out to be done quickly and without difficulty or delay.

Manufacturing process

In order to properly apply the prepared materials, it is worth adhering to a certain algorithm:

Take four metal sheets not less than 8 mm and weld the edges together, it turns out a cube without a bottom and a lid.
Cut out opening in one of the walls. It is intended for laying firewood, so it is worth making a larger hole.
mount doors furnaces. Cut from metal of the same thickness.
Take another sheet of metal, to which at the corners weld pre-prepared steel thick corners at least 10 mm playing the role of legs for installing the structure.
Weld the bottom to the body and organize blew for furnace draft control in the future.
Do cover ovens. Take a metal sheet of the same thickness. Cut a hole in it, to which in the future we will weld a pipe that serves as a chimney.
Craft platform in front of the furnace performing the role of fire safety. To do this, take a less thin steel sheet and screw it to the floor under the firebox door.
Produce heat-resistant lining to improve fire safety. This step is optional, but following it will reduce the chance of an accidental fire. What is useful if the stove is inside a summer house or a private house.

Advice. It is quite simple to execute the described algorithm. A person will cope with the assembly, skilled in the use of a welding machine and those who want to save money by making a heating unit on their own, capable of quickly heating the room and consuming a small amount of wood fuel.

It won't take long to make. A person with little experience in such matters will be able to build a metal furnace in a few hours. In any case, the procedure takes a shorter period of time than the laying of a stone structure with a large number of time-consuming steps.

Photo of stoves: compact country house, fireplace and long-burning device

Photo 1. A small homemade iron stove, ideal for small spaces. Heats up quickly and takes up almost no space.

Photo 2. Metal fireplace. A fairly simple device to manufacture, which not only heats the house, but also decorates it.

Photo 3. Homemade long-burning stove. A more complex and bulky unit that allows you to warm a whole country house.

Possible difficulties

One of the troubles during the service of a metal furnace are heat loss. This is due to the fact that the metal is a bad battery and quickly gives it away. To solve this problem, a special shield representing brick structure surrounding the oven on three sides. Before laying the walls, the building material is immersed in water in order to improve adhesion. If desired, the shield is faced with a special tile.

Another problem is the emergence condensate due to the cooling of combustible gases generated during the operation of the furnace. The problem is solved by pipe shortening intended for removal of smoky masses.

Possible troubles include the inexplicable smoke the room where the oven is located.

This phenomenon indicates that welds, fixing the edges of the metal sheets forming the body, not tight.

This happens when an inexperienced person performs welding. To resolve this issue, joints are welded several times. The impermeability of the hull is tested with water. If no leaks are found, then no smoke will follow in the future.

Fast burnout of the bottom and walls firebox is a serious problem. To prevent its occurrence, metal sheets are selected thickness from 5 mm. A body welded from such elements will not undergo burnout and will serve properly for a long service life.

Increased fuel consumption testifies that thrust ovens poorly regulated. To get rid of this problem, and reduce the consumption of firewood, equipped with special doors performing regulatory functions.

Useful video

A video demonstrating a homemade metal fireplace stove: appearance, design features, kindling.

Conclusion

When operating a metal furnace, some rules are observed. To avoid accidental fire necessary:

Bookmark refractory materials in places close to open flames and heat.
Flammable materials near the oven separate with basalt or asbestos.
Chimney fence off non-combustible materials with thermal insulation properties.

Compliance with the described conditions will not allow accidental ignition to spoil the owner's opinion about the stove, which he built on his own.

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