Heating boilers using sawdust - significant savings

Heating appliances with gas equipment are noticeably crowded out by structures operating on solid fuel. The efficiency and efficiency of solid fuel boilers is constantly increasing thanks to design improvements, the introduction of the latest technological developments, and the expansion of the range of raw materials used. One of the promising and economically viable representatives of such equipment is a sawdust boiler.

The device is still rare. But the owners who use it for heating (private houses, greenhouses, production workshops, private workshops, and other premises) are confident in the irreplaceability of the boiler and are satisfied with the purchase.

How to assemble it yourself?

The basis for the manufacture of a sawdust stove is a 200 liter whole steel barrel without rust.
A propane tank, a piece of steel pipe, or a large fire extinguisher will work well. In this part, the main indicator is the wall thickness; the service life of the entire product depends on it. Other materials you will need:

• Material for the legs (with a round base), which can be used as pipe scraps, pieces of reinforcement, channel, etc.
• Two steel circles with a barrel diameter and a wall thickness of 5 mm.
• Ready-made or self-made door.
• The pipe is 15 cm longer than the barrel, and 100 mm. in diameter.
• Pipe, 5 m long and 100 mm in diameter. for the chimney.

You will need the following tools:

• Gas cutter or grinder.
• Welding machine.
• Hammer
• Measuring tools (tape measure, level).

1. Before making a product with your own hands, carefully study the drawing, after which they begin assembly, consisting of the following steps:
2. Preparing the fuel tank. The upper part of the barrel is cut off after preliminary precise marking, so as not to spoil the workpiece. Also, according to the markings, the bottom is cut off, which is not thrown away, but will be used as a lid.
3. Making the bottom of the furnace from a steel sheet, which is cut to the diameter of the firebox. A hole is made in its center along the diameter of the supply pipe.
4. Manufacturing a pipe supplying oxygen to the combustion zone. To do this, you will need a workpiece longer than the fuel tank, and equal in diameter to the hole in the firebox. In it, longitudinal lines are cut with a grinder or perforations in an amount of more than 50 pieces are made with a drill.
5. A perforated pipe is inserted into the middle of the bottom and welded, after which a cover is cut out with a hole in the center, adjusted to the diameter of the pipe (the cover is placed on it). An additional hole is also made near the edge to control draft and air access, on which a movable damper is placed. For convenience, the cover is equipped with arches for ease of maintenance.
6. Installation of a chimney from a pipe with a diameter of 10 cm and a pipe connected to it with a clamp. The pipe is carefully connected by welding to the side outlet at the top of the firebox and a pipe is put on it.
7. The boiler is installed on supports, which are made of metal profiles welded to the furnace body, as indicated in the drawings.

All parts of a stove operating on sawdust become very hot, which is why the boiler used for heating the room should not be installed next to flammable materials and surfaces, and should not be left unattended. It is prohibited to service the device without protective gloves and in violation of fire safety regulations.

Self-production of boilers

When you need a heating device in your home, but don’t want to spend a significant amount of money on purchasing it, you can make it yourself. For this you will need:

Do-it-yourself sawdust boiler - device diagram

• pipes with a round profile 4-5 cm in diameter;
• rectangular pipes 60X40 mm;
• welding machine;
• electrodes;
• Grinder.

The pipes are selected so that they fit in a boiler measuring 36x40x80 cm. Structures with a rectangular cross-section will serve as vertical posts. Round holes are created in them for attaching other elements of the device.

On the wall of the boiler with a door there will be pipelines 5 cm in diameter. For the back, you need the first four rectangles measuring 5x6 cm, and the next four rectangles measuring 4x4 cm.

To connect the pipes, holes of 5 cm in diameter are cut. Cold and hot water will flow through them.

Manufacturing process

The front and rear parts of the boiler are equipped as follows:

• rectangular posts are attached by welding;
• round pipes are installed perpendicular to them;
• pipelines for water supply and drainage are connected;
• the open ends of the pipes are closed with pieces of metal sheets and welded.

The process of making a sawdust boiler
The boiler is checked for leaks - water is poured into the pipes to immediately detect leaks. If everything is in order, the device is mounted in a brick firebox. You can make it yourself using fireproof materials.

Principle of operation

The boiler is loaded with fuel from the top, from the bottom to the chimney cut. It has neither doors nor an ash pan. Chips and sawdust are compacted with a special weight made from a thick sheet of steel. A pipe is welded to it, through which air is supplied to the firebox. It passes vertically through the lid, its end comes out - the boiler is ignited through it.

The process of a homemade sawdust boiler

The point is to burn the top layer of biomass, the whole process moves downward. This is how the water jacket heats up.

A damper is mounted at the end of the pipe - it helps regulate the air supply to control the rate of fuel combustion. During operation, sawdust becomes less and less, the load drops lower until the boiler is empty. It is released from combustion products through the chimney.

When making your own, be sure to use drawings - this makes it easier to figure out the proportions and shape of the parts. For the device to function properly, it must be assembled correctly.

Modification of a stove for heating a home

Houses are larger in area than greenhouses, so it is necessary to ensure that a long-burning sawdust stove provides more energy and can warm a larger area. Stoves made using the method described above have one significant drawback: thermal energy is lost when exiting through the chimney. It is not always advisable to extend the chimney over the entire area of ​​the heated room, so we recommend so-called sawdust pyrolysis stoves. They are characterized by having an additional air circuit for flue gases. There are two options to convert an existing stove: install a smoke circuit from the outside or from the inside.

It’s easier to install it outside, that is, surround the stove with another layer of metal, leaving space for the free movement of hot air. This design makes it possible to keep the volume of loaded fuel and, accordingly, the frequency of its loading unchanged. Installing an additional circuit inside the structure is done in approximately the same way, but has a small drawback: you can load less sawdust. In both cases, the chimney should be located at the bottom of the structure. As can be seen from the description, making a sawdust stove with your own hands will not cause any difficulties if you know how to use a welding machine.

Water boiler

Heating of the room can be done using water or air. If there is a water supply in the house, you can assemble a system with your own hands with circulating water between the heating boiler and radiators or a “warm floor” system.

In the body of the boiler itself for water heating, the pipes are in water, which will be heated by the action of hot air passing inside them. This system is similar to a gas water heater

Rice. 2 Water double-circuit heating boiler system

The circulation of water through the system begins even before it enters the boiler.

For optimal system operation you need:

• controller for water level in the tank;
• overflow so that the water does not exceed the permissible level;
• a pump that lifts water from the radiator circuit;
• lower outlet for water intended for floor heating.

It is difficult to make such a sawdust boiler with your own hands, but a house equipped with such equipment will be very comfortable to live in all year round.

How to make a long burning stove

To make a sawdust stove with your own hands, you can use a ready-made metal container: a barrel, a can, an empty gas cylinder or a pipe of a suitable diameter. To work you will need a welding machine, an angle grinder and skills to work with them.

A simple sawdust stove from a barrel

If you have a metal barrel at your disposal, then first of all you need to cut off the top from it. This should be done carefully, since in the future the part will be used for its intended purpose, but as a removable cover.

Next, a circle with a diameter slightly smaller than the parameters of the barrel is cut out of a metal sheet with a thickness of at least 3 mm. In the center of the circle, make a hole for a pipe with a diameter of 10 cm and carefully weld the resulting workpiece to the inner walls, departing 15-20 cm from the bottom.

Just below the welded sheet, a small window is cut out - a blower, to allow the oxygen necessary for combustion to enter the firebox. A hole for the chimney is cut out in the upper part of the cylinder; a pipe is welded to it to remove carbon monoxide from the firebox.

The chimney requires special attention - too powerful a draft will contribute to the rapid release of gases and reduce the thermal efficiency of the device. If the draft is weak, another problem may arise - life-threatening combustion products will begin to enter the room.

Experienced craftsmen recommend artificially lengthening the chimney pipe by running it around the perimeter of the room, or adapting the chimney for preparing hot water by including a boiler in the design. All this will help keep the house warm and get the most out of it.

The lid is made from a cut off top, welding the sides to it, or from a metal sheet

It is important to ensure the tightness of the structure, otherwise combustion will occur instead of smoldering. For the tightest possible connection, special heat-resistant seals for furnaces are used. For convenience, be sure to weld the handle

For convenience, be sure to weld the handle.

Rules for operating a homemade stove

For all its effectiveness, the homemade device works simply:

1. A cone-shaped pipe is installed into the hole in the metal sheet - this is easier to remove at the right time.
2. The container is filled with sawdust to the level of the chimney in small portions, carefully tamping each layer.
3. The pipe is carefully removed, leaving a hole in the center for oxygen to enter the fuel and exhaust gases to exit.
4. The stove is closed with a lid and the fuel is ignited from the ash side. To make kindling easier, you can pour some flammable liquid onto the metal partition before loading the sawdust.
5. The smoldering process in a barrel with a volume of about 200 liters lasts at least 8 hours - during this time the stove lid cannot be opened and sawdust should not be added. A new load can be made only after the previous batch of fuel has completely burned.

How to improve the budget model

The simplest potbelly stove made from a barrel is suitable for a country house, garage or greenhouse. For a residential building, it is recommended to modernize the structure by increasing the heating area by constructing an additional smoke circuit.

The contour can be made external or internal. In the first case, you will need a similar mold of a larger diameter, and in the second you need to find a slightly smaller barrel or weld a suitable metal container.

The external contour is attractive by increasing the heat transfer area and maintaining the volume of the combustion chamber, while the internal contour is easier to operate. In both options, the chimney should be moved downwards.

It is better to make the cover from a thick steel sheet with a thickness of at least 5 mm and reinforce it at the edges, otherwise it will quickly deform from high temperature.

Making a potbelly stove

Long-burning potbelly stoves are good because they are made from any available materials - these are various barrels, old capacious cans, pieces of large-diameter pipes or simply sheet metal. We chose sheet steel as the starting material - it is a more convenient material to process. You can adapt a barrel for this, but doing work in its internal volume is not very convenient.

All sizes are presented rather as guidelines, a kind of averaged best option. You, in turn, can deviate from the dimensions of the parts to create a stove that satisfies your specific wishes.

The design of a long-burning furnace is quite clear from the drawing presented above. Here are its main components:

• Combustion chamber - wood burns in it with the formation of pyrolysis gas;
• Afterburner – combustion of pyrolysis products occurs in it;
• Doors of the combustion chamber and ash pan - they are purchased in the store, but you can make them yourself;
• Chimney - in most cases it is a pipe with a diameter of 100-150 mm.

You can deviate from the drawing in one direction or another. But remember that as the size decreases, the burning time decreases and the power of the long-burning stove decreases.

The lower the power, the smaller the heated area. Therefore, it is best to provide a small reserve.

To make a long-burning stove like a potbelly stove, we need sheet steel with a thickness of at least 3 mm - this will ensure a long service life of the heating equipment. If the steel is thin, it will begin to burn through - after a couple of seasons, holes will form in it

Therefore, special attention is paid to the thickness of the steel. The optimal thickness is 3-5 mm

For our example, we will take the classic scheme of a potbelly stove, modify it and get at our disposal an effective wood-burning stove for a home. At the initial stage, we prepare the side sheets - in our drawing they have dimensions of 450x450 mm. Next, we make the lower walls, front and rear walls - their dimensions are 200x450 mm. As a result, we should get a rectangular box. But don’t rush to weld it together - there is a lot of work ahead.

First you need to make a base - this is the bottom wall and two side ones. We weld them together, weld the grate at a height of 80 mm from the bottom. Now we need to prepare the front wall of the long-term heating oven - we weld both doors into it, and then weld it to our structure.

We prepare two metal sheets measuring 200x370 mm. We weld the first of them to the front and side walls at a height of 160 mm from the top. Next, we prepare the back wall - we weld small metal tubes into it, which should fit into the space between the two inner sheets that form the afterburning chamber - secondary air will be supplied through them. Then we weld the back wall and a second metal sheet at a height of 80 from the top (welded to the side and rear walls).

The damper is used to regulate air flow. It is this that improves the efficiency and quality of traction.

Our DIY long-burning stove is almost ready - all that remains is to figure out the top cover. We make a hole in it with a diameter of 100 mm and weld a piece of pipe for the future chimney. Now it remains to find out whether you need a hob or not - it is also welded into the top cover. At the last stage, we install the lid in place and weld it - the stove is ready, now it can be installed on a non-combustible base, attached to the chimney and started.

When starting the long-burning stove presented above, let it burn, then cover the ash pit so that the wood barely smolders and the generation of pyrolysis gas begins.

Another interesting long-burning pyrolysis furnace is shown in the following figure. It is made from a barrel or a piece of large diameter pipe and is equipped with a suitable lid. In the lower part, at a distance of 80-100 mm from the bottom, a metal disk with a hole in the middle is welded. A door is welded between the disk and the bottom, on the side wall. The resulting space forms our firebox. We weld a chimney with a diameter of 70-100 mm in the upper part.

In terms of low cost of use, such a stove is a real gift, since there is no shortage of sawdust in a private home.

The resulting long-burning furnace receives heat by burning pyrolysis gases generated when heating sawdust. The sawdust itself is poured into the main volume, and to prevent it from spilling into the firebox, it is compacted using a wooden cone. When the stove starts, a fire is lit in the firebox, the cone is removed - after a while the unit will begin to produce heat.

What is this type of fuel made from?

The material for making fuel chips can be any wood, so most often this type of fuel is made from dry branches and various wastes that remain after processing or processing wood.

At the same time, the finished product retains all the features of the original wood, therefore such characteristics as:

• calorific value;
• ash content;
• specific resin content,

completely correspond to the trees from which the chips were obtained.

Because of this, pine chips are not suitable for modern automatic boilers, because the high resin content not only increases the ash content, but also leads to the appearance of deposits in the chimney and on the heat exchanger parts.

Between starting the boiler and heating the water to operating temperature, at least an hour passes, during which condensate containing a lot of resins settles from the hot smoke onto the cold pipes.

In addition, the calorific value of hard and heavy wood chips is always higher than that of light and soft wood chips. After all, the finished fuel only preserves the original characteristics of wood.

If the fuel is obtained from wood with bark, then its calorific value decreases, because this parameter of the bark is much lower than that of other parts of the tree, with the exception of needles and roots.

Suitable heating systems

For heating privatized houses and any buildings with sawdust, similar designs :

• heating stoves;
• heating stoves with a water-type heating register or air heater;
• water heating system with heating devices;
• warm hydraulic floor;
• air type heating;
• heated air floor.

Heating stoves heat the space around them , making them suitable only for small houses . At a distance of 10 meters from the stove, the temperature drops by 10–15 degrees, so in large houses the stove usually acts only as an additional heating device.

Heating stoves with a water-type heating register or heater combine the advantages of stoves and boilers. They provide the same heat as an ordinary heating stove and heat the coolant, which flows through pipes or air ducts to remote rooms.

The large mass of the stove turns it into a heat accumulator ; thanks to it, you will not need to reheat the boiler every 2 hours or add firewood to it every hour. The stove will maintain the temperature of the heat carrier for up to 6–10 hours , thanks to this you will be able to heat it 2–3 times a day.

A water heating system with heating appliances in any room can be used both with a water boiler and with a sawdust-fired stove, if a water register . Like any other water heating system, it will operate on natural or forced circulation of a coolant.

In systems with convective circulation, hot water first rises to the ceiling, then descends into each room and flows either to the heating devices or to the heated floor. In systems with forced circulation, water is driven by a pump, thanks to which all pipes can be laid under the floor.

Water and air heated floors not only heat the room, but also improve its climate. In winter, it is especially pleasant to walk on the floor without shoes, feeling its warmth with your feet. The main disadvantage of heated floors is the high price of materials and work, because you not only need to install air ducts or a water pipe, but also qualitatively insulate the space between the floor and the ground or foundation.

Air-type heating is just as expensive as heated floors, because you need to install air ducts throughout the house, and also install automated humidifiers due to the strong drying of the air. Ovens with heaters can be used as a heat source.

The only difference between furnaces and boilers is that the boiler has a water jacket , in other words, the space between the hot body and the outer casing is filled with water.

Here are the characteristic features of each radiator:

• stove - bright heating of the air and the space around it;
• heater - heating air for delivery to other rooms without heating the space around it;
• stove-heater - heating the space around and heating air for delivery to other rooms;
• stove with a register - heating the surrounding space and water for delivery to other rooms;
• boiler - heating water for delivery to other rooms.

Thanks to this, air heaters and boilers are installed in utility rooms and are often insulated from the outside. After all, there is no point in wasting heat energy on strong heating of the utility room, and the less heat spent on this, the more other rooms will get.

Sawdust stove: advantages of use

Such heating systems have many advantages:

• every summer resident will find fuel for their work; wood chips and sawdust, including pressed ones, are suitable for this;
• there is no need to dispose of waste, it can be burned in a furnace;
• damp wood chips, firewood and sawdust do not need to be dried first, they can be stored in this form;
• maximum power is achieved in a short period of time;
• boilers give off the maximum amount of heat;
• anyone can assemble this system, and its maintenance does not require special skills;
• a boiler of this design can also be used for heating water and cooking, if supplemented with appropriate equipment;
• the ability to control your fuel costs;
• the temperature of the heated water can be adjusted;
• harmful substances burn out in the firebox without harming the environment or atmosphere.

Subtleties of installing solid fuel boilers

The boiler piping scheme is adopted in accordance with the characteristics of the heated object.

You can implement it using one of the following options:

• boiler in an open heating system with natural circulation and radiators;
• boiler in a closed system with forced circulation and radiators;
• boiler with thermal accumulator in a closed forced system with radiators;
• boiler with thermal accumulator in a closed system with forced circulation and heated floors;
• boiler with radiators and heated floors as part of a forced circulation system.

The piping of a solid fuel boiler must be equipped with a safety system. The latter includes:

• heat accumulator or buffer tank;
• three-way valve for adding cold water;
• thermostat in the control system.

Solid fuel boiler safety group

Immediately before installing a solid fuel boiler, it is necessary to carry out a visual inspection and test firing in the open air for about 1 hour at maximum load of the combustion chamber.

According to the requirements of SNiP, after connecting the boiler, a hydraulic pressure test of the system should be carried out for 24 hours.

To do this you need:

• connect the water, open all taps and shut-off valves;
• increase the pressure in the system to 1.3 atm (with a control valve);
• make sure there are no leaks, especially at welded and threaded connections.

If the installation, piping and connection of the boiler are carried out correctly, there will be no pressure losses or coolant leaks. In this case, you can begin to inspect the boiler itself:

• checking the installation of grates and fireclay;
• setting the ignition valve to the extreme position to ensure optimal traction;
• checking the quality of installation of plugs, combustion chamber doors and other elements of the boiler design.

Features of boiler operation

The most modern and reliable type of sawdust boilers are automated water heating systems. Their design consists of several main parts:

• fuel bunker;
• gas generator;
• hot water boiler - consists of a combustion chamber and a heat exchanger;
• automatic control system.

Modern sawdust boiler - device
The body design includes the following elements:

• firebox;
• chimney;
• ash pan;
• heat distributor;
• coil;
• blower;
• sensors

Depending on the building design, it can be installed entirely inside, outside, or partially installed outside.

The automatic system is responsible for the following operations:

• feeding wood chips into the boiler;
• supply of hot air in the combustion chamber in accordance with the volume of fuel;
• temperature rise control;
• firefighting.

Among the imported boilers of a similar device, we can highlight the Austrian HARGASSNER. They are especially popular in Europe for heating hotels, houses, and office buildings.

A prominent representative of domestic boilers is BIO VULKAN produced. The main features of these devices:

Boiler BIO VULKAN – general device

• The firebox body is made of steel sheets and pipes, externally coated with heat-insulating material.
• The interior is lined with fireclay bricks, which increases the heating temperature.
• Sealed doors with a concrete body, large and heat resistant.
• Fans supply primary and secondary air to the firebox - this is necessary for combustion.
• The drum heat exchanger is protected from lime deposits by two-level water circulation.

These sawdust boilers have the highest efficiency, which is due to the installation of a five-pass heat exchanger on them. To burn fuel, a retort burner is used, which allows the use of wood waste with a fraction of up to 4 cm.

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Fuel supply mechanism

Solid fuel heating boilers operate autonomously and can be done with virtually no maintenance. Sawdust is supplied using several means.

The receiver has open access to the outside of the building. It is equipped with a screw drive connected to the storage. When the bunker is fully loaded with fuel, the conveyor starts working - it supplies fuel to the mechanized compartment.

There are two types of storage, they differ in the technique of feeding sawdust into the boiler:

• a hopper with an inclined base, cone-shaped, with a screw mechanism in the lower part;
• agitator with blades, sawdust is loaded by rotation.

Not all fuel from the storage goes directly into the firebox. Wood chip boilers of the pyrolysis type are equipped with a drum and a screw transmission, which supply fuel in parts.

Quality control

Before loading and igniting the unit, it is necessary to check the tightness of the water jacket and check the quality of welded joints . This will require an air compressor. You can test seams in two ways, which are very reliable:

• Hydraulic. The entire container is filled with water, a compressor is hermetically connected to the fitting, which should create an excess pressure of 2-3 bar. Water does not have the property of being compressed, so it will flow through all uncooked places.
• Pneumatic. Pressure is created without water, and all welds are coated with soap foam using a brush. The bubbles will show where air is leaking through. During the test, the pressure drop can be monitored using a pressure gauge on the compressor.

There is such a type of solid fuel heating source as a sawdust mine boiler. Its design and operating principle are different and more complex, although it is also quite possible to make it on your own. It works due to the fact that sawdust is burned in the lower part of the unit, pouring there from the bunker, this can be seen in the figure.

The process continues in smoke pipes, which intensively heat the coolant. The principle of afterburning wood gases (pyrolysis) is used. Operation efficiency is increased by installing an air blower - a blower fan. Making a boiler using sawdust and tyrsa with your own hands is not so difficult in practice, but it will definitely give a noticeable economic effect both during production and during further operation.

Automatic boilers for coal and wood chips

The design and principle of operation of these units is not much different from pellet ones. The screw conveyor in the same way supplies coal to the firebox at the command of the control unit, air injection and ignition work in the same way. The difference is in the design of the auger itself; for coal it is made more massive, and accordingly, the power of the electric motor is increased. In addition, a coal solid fuel boiler with automatic fuel supply requires fuel of a certain quality and humidity. This is due to the design features of the retort burner used in such heat generators.

Heating units that burn wood chips have one additional function in the feeder - wood chopping. After all, the length of the chips can be different and it is impossible to provide an auger for it. To make the chips the same size, a rotary chopper knife is built into the supply pipe between the hopper and the auger. Both the conveyor and the knife are driven by one powerful electric motor. Such products are offered by many European manufacturers, for example, the Austrian automatic solid fuel wood chip boiler FROLING.

A little about universal units. Their convenience is that if there is a shortage of any type of bulk fuel, you can switch to regular firewood at any time. For this purpose, the design provides an additional combustion chamber for storing wooden logs. Of course, the efficiency in this case is significantly reduced (from 90 to 80%), since the heater operates in the mode of a simple solid fuel boiler. One more circumstance should be noted: every manufacturer of automatic boilers is trying to expand the range of fuel burned by modernizing the supply system. Therefore, some products, in addition to pellets, can use coal dust, eco-peas and even seed husks. An example of this is the Polish universal boilers DEFRO DUO UNI.

Boilers with top chamber placement

There are also boiler models that operate in exactly the opposite direction. Folk craftsmen designed one gasification chamber at the bottom and another at the top. These types of boilers are not yet so popular, but their advantages are already obvious:

1. The system operates on natural draft using a new solution in the design of air channels.
2. Eliminates the use of electricity.
3. "Inverted" design.

The bottom line is that the pyrolysis gas enters the upper chamber and combines with secondary air. Discharged air enters the boiler through the lower hole, combines with oxygen, and forms a medium for the oxidation reaction. The flammable gas burns in the lower chamber and releases heat to the water. The special hardened steel of the boiler allows clear smoke to exit the chimney.

Fuel requirements

The efficiency of boilers directly depends on the moisture content of the sawdust. The use of dry shavings and sawdust from carpentry as fuel does not cause problems. The bulk of sawdust, as noted, is waste from roundwood sawing shops.

Industrial waste from sawing round timber on band sawmills is small (up to 0.3 mm) sawdust with a moisture content of up to 80%. Even with constant forced air supply to the firebox, such sawdust burns very slowly, since it takes time to dry it. An even greater problem when burning is damp, long-stored sawdust, compacted into a damp, dusty mass.

Such fuel should be burned in a certain mode:

• Dry and wet fuel should be supplied to the combustion chamber in a ratio of 3:1.
• The supply of raw fuel can only be started when the boiler reaches full power after ignition.
• Constantly force air into the combustion chamber using a fan.

Fuel loaded - start

Boiler ready for operation

• You can ignite the fuel.
• You can set fire without the lid installed, but it is better to install the lid right away, and pour a little waste with kerosene or gasoline into the ash pit, 50 g is enough.

Our advice: to regulate the draft on the blower, you can install a damper in the chimney.

• After the fuel ignites, it is necessary to close the damper to ¾ of the hole.
• After 2-3 minutes, the damper must be slightly opened and the required air supply adjusted.
• When the oven reaches operating mode, you can hear a steady hum. Using the damper, the operating mode of the oven is regulated.

Dryness is the main requirement for fuel

The dry sawdust heating boiler operates without problems, with the maximum power declared by the manufacturer. But due to various factors, wet raw materials are also used for heating, reducing the efficiency of the device. Up to 30% of the power is spent on drying the fuel, from which steam is released. The gas obtained during pyrolysis from steam becomes heavier and combustion worsens as a result.

When using sawdust of different humidity for heating, it is important to follow useful recommendations:

1. The raw material is fed into the boiler furnace after it reaches full power as a result of ignition with dry mass.
2. The optimal ratio of wet and dry sawdust when fed into the firebox is 1:3.
3. Air must be forced into the combustion chamber.

Operating principle of the furnace

Protective systems and operating modes

The sawdust boiler must include an ignition protection system. Due to this, such devices can be installed in residential buildings. In addition, the heating system is equipped with special sensors that give a signal when smoke accumulates. Such a device notifies about the occurrence of a fire at the first warning signs.

The automatic unit operating on sawdust has several modes:

1. Maximum. This position is used when loading a large amount of wood raw materials into the firebox. In this case, fuel is used efficiently, since the combustion intensity gradually decreases when the coolant and air masses are heated.
2. Average. Used if a heating system warm-up period is required. Much less fuel is consumed when the temperature is lowered to the required level. After this, the heating intensity increases, and with it the consumption of raw materials.
3. Pause mode. It is used when it is necessary to stop the heating process. In this case, the fuel stops burning and the system gradually cools down.

Such boiler operating modes and its protection system contribute to the safe and convenient use of the device.

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Cost of popular wood pellets

Price table for the most common types of pellets.

Choosing the type of solid fuel boiler

How to understand which boiler will be optimal for servicing a particular heating system? Obviously, you need to decide on the type of fuel, the required power of the unit and the features of its design, installation process and subsequent operation, as well as the features of the connected heating system.

Homemade solid fuel boiler

Among the materials that can be used as solid fuel, the most widely used are:

• coal;
• peat briquettes;
• pellets;
• firewood;
• sawdust and other combustible production waste.

Types of solid fuel for heating boilers in the photo

The choice of the type and design of the heating boiler directly depends on what fuel you are going to use, the required performance of the heating system, as well as the place where it will be installed. The following modifications of solid fuel heating units are suitable for self-production:

1. Classic

Equipped with a steel or cast iron heat exchanger, they can be used for both heating and hot water supply. The efficiency of such boilers is about 85%.

Classic solid fuel boiler

1. Pyrolysis

They ensure separate combustion of fuel and the volatile gases released, thereby significantly increasing the efficiency and, consequently, the cost-effectiveness of the heating system.

Diagram of a solid fuel pyrolysis boiler

1. Pellet

The efficiency of this type of heating boiler reaches 90%. Their main advantage is the high degree of automation of work processes, and the disadvantage is the complexity of the design.

Operating principle of a pellet boiler

1. Long burning

They are able to operate continuously throughout the entire heating season, requiring fuel loading once every few days, which distinguishes them from classic solid fuel boilers.

Layout of a long-burning solid fuel boiler

Additional recommendations

If a homemade sawdust boiler is used to heat a private home, it would not hurt to supplement it with some safety equipment . To do this, holes are drilled in the water jacket casing and fittings for temperature and pressure control devices are welded. It would be correct to additionally install a relief safety valve, which would be activated when the pressure rises to 3 bar, and lead the pipe from it to the street.

The hot surfaces of the unit and chimney also pose a danger to people if it is in the house. At the same time, heat spreads where it is not needed - in the combustion chamber. For these reasons, sawdust heating boilers must be insulated. Basalt wool can be used as a thermal insulation material; it can withstand high temperatures well. The insulation layer can be covered with thin sheet metal with a polymer coating, at the same time solving the issue of aesthetics of the appearance of the unit.

In the case when only sawdust is used as fuel, it is necessary to make a device for properly loading it into the firebox. The fact is that this type of fuel does not allow air to pass through well, and without it the combustion process will be weak . Therefore, a pipe with a diameter of 100–120 mm in the form of a funnel is made from thin metal, only the sides of the cone are very flat. The device is placed vertically in the center of the firebox, after which sawdust is poured around it and periodically compacted tightly. When the chamber is full, thanks to the cone shape, the pipe can be easily removed, a load is placed and the firebox lid is closed.

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Principle of operation

Now let's look at the general design of boilers using wood chips and sawdust.

The device body consists of the following elements:

• firebox;
• ash pan;
• coil;
• chimney;
• blower;
• heat distributor;
• sensors

Hargassner boiler structure

In the firebox, on a special grate, the combustion process of woodchips and sawdust occurs, thanks to which all the ashes and ash remain in the ash pan. This device should be cleaned approximately 2 times a month.

Due to the fact that wood chips and sawdust are waste from wood processing and do not form a large flame, the heat exchanger in such boilers is heated by hot gases passing through it.

The heat exchanger consists of tubes that are connected in parallel. It is made of a material that can withstand high temperatures well and does not rust, and it also has such quality as a high level of thermal conductivity.

Sawdust and wood chips are an especially economical type of fuel if there is a nearby source of fuel: wood processing.

Wood chip boiler Hargassner WTH 150-200

pyrolysis

In order for the gas to be burned, the boiler furnace consists of two separate chambers. In one the fuel itself burns, in the other the gas coming from the first chamber burns.

Heating boilers operating on sawdust and wood chips, like other heating devices, are single-circuit and double-circuit.

The former are intended exclusively for heating the room, the latter are also capable of heating water. Such units are in demand among owners of private houses, because... They allow not only to provide the house with heat, but also to install plumbing in the house.

Pros and cons of using sawdust as fuel

Advantages and advantages of sawdust when used in solid fuel boilers:

• The efficiency of modern devices using sawdust reaches 80-90%.
• Sawdust fuel is environmentally friendly; raw materials are burned without releasing toxins into the atmosphere, with a minimum amount of soot and remaining ash.
• Low cost, which sometimes only includes the cost of shipping free wood waste.
• Availability and availability of sawdust in any region. In case of short-term interruptions in raw materials, solid fuel boilers can easily be converted to processing bark, wood chips, and firewood.
• You can burn sawdust immediately without additional preparation (cutting, chopping).
• Wet raw materials are suitable for use.
• The economy of using sawdust is confirmed by the following statistics - a pyrolysis boiler using wood chips and sawdust from one portioned load of fuel operates for heating for up to 12 hours, the coolant (water, antifreeze) heats up efficiently and provides comfortable warmth in the room within 0.5 hours after igniting the heating device . At the same time, the cost of generating the same amount of thermal energy for a pyrolysis boiler is 4 times less than for a conventional wood-burning boiler and 10 times less than for a gas boiler.

This type of solid fuel has fewer disadvantages:

• Bulk bulk material is not convenient for transportation; it requires spacious storage with good ventilation and compliance with measures when storing a flammable product.
• Sawdust combustion is characterized by low parameters.
• For the convenience of working with fuel, you need containers - bags, baskets, and other special containers.
• The chimney needs to be cleaned periodically.

Installation device

Such equipment includes a special damper. It is used to dose the air entering the combustion chamber. When sawdust smoulders, flue gas is generated, producing a large amount of heat.

There are two types of long-burning equipment:

1. The first involves the rise of furnace gas during fuel combustion upward through compressed sawdust and subsequent entry into the chimney.
2. Another type of it differs in that the gas, rising, ends up in the outer loop. It is there that it cools down, after which it is disposed of through the same chimney.

A typical long-burning stove model includes a certain set of components. Thanks to them, efficient heating and fuel economy are ensured.

The most significant in its composition are:

1. Fuel tank. It is equipped with a damper, with which you can regulate the flow of primary air into the ignition chamber.
2. Afterburners. They have holes through which secondary air enters the firebox.
3. Chimney.

Diesel fuel, natural gas, electricity

Of the other types of fuel, the most popular are diesel fuel, natural gas, and electricity:

1. Diesel fuel has a fairly high calorific value, and its cost is much higher than many other types;
2. the cheapest way to heat your home is to use natural gas: systems running on it are safe and reliable;
3. Electricity allows you to use a wide variety of equipment to provide heat to your cottage, but if you use it year-round you will have to spend a decent amount of money.

Video material

Independent processing of wood waste using a screw press of your own production will be rational only if you have free time and affordable raw materials. Therefore, carefully weigh the pros and cons of such a decision before embarking on the process of creating equipment.

Technology for making briquettes from vegetable waste

It is unprofitable to burn fuel raw materials without processing, and the production of briquettes and their widespread use in everyday life and in enterprises is indisputable proof of this. Pressed fuel from plant waste, for the production of which wood scraps, wood chips, sawdust, sunflower husks, corn stalks, straw, etc. are used, is produced using special technologies, including:

Equipment for production

• RUF is a method of pressing plant mass, without special surface protection from moisture. Equipment – ​​a press for the production of fuel briquettes in the form of bricks. The use of technically simple equipment does not require qualified personnel, so the cost of such products is low. However, due to instability to moisture, briquettes for heating of this type cannot be transported over long distances - as a result of saturation with moisture, the product loses some of its specific qualities.
• Nestro – production of fuel briquettes of elongated cylindrical shape (50×10 cm) occurs on high-performance presses, with low energy consumption. The resulting products are subject to accelerated sale and use; otherwise, due to high humidity, they lose their shape and ability to be transported.
• Extruder technology (Pini&Kay) is known as the most effective, providing the highest quality products. Extruder presses produce various types of compressed fuel, including coal briquettes with increased technical advantages, resistant to high humidity and mechanical stress. The production of briquettes on extruder (screw presses) is characterized by a high degree of heat treatment of the product, which, in combination with pressing, provides the final product with increased density due to lignin released under the influence of elevated temperatures, which has adhesive and compacting properties.

Each presented technology for the production of fuel briquettes is developed taking into account the conditions in which these products will be used. Thus, sawdust briquettes and peat briquettes, which are characterized by relatively low heat transfer, are more often used as stove briquettes for heating small rooms in private households. Popular heating devices for this type of fuel are peat boilers and stoves designed for peat briquettes for heating.

The best known manufacturers and models: characteristics and prices

When choosing a boiler for sawdust and wood chips, in addition to technical characteristics, you should pay attention to the country and brand of the manufacturer. Northern European countries have learned to squeeze the highest economic performance out of fuel

To this end, they have been working for a long time on improving automation specifically for private homes, and given their desire for comfort and environmental requirements, you should pay attention to the products of the companies Hargassner, Froling, ETA. Of course, if the budget allows.

Russian-made boilers, especially if the developer is a well-known European brand on the market, may well be competitive. At a significantly lower price, they are quite capable of providing both the reliability and comfort of a private home. In addition, they are unpretentious in raw materials and maintenance, and the automation even in European solid fuel boilers is often from China.

Specialized

These are boilers designed primarily for the use of bulk solid fuels.

Pyrolysis Master BIO-15

One of the best sawdust boilers for heating a private home. It also works on wood chips, peat, and sunflower husks. With the use of replaceable burners it can burn straw. Thanks to a five-pass heat exchanger, it has a high efficiency of 91% and has a hopper capacity of 200 liters. The only drawback is its considerable dimensions.

Cost: 185,000-240,000 rubles.

FACI FSS 115

It is produced in Russia, but the developer is Italy. This is an automatic industrial boiler for burning wood waste. Power adjustable within 25-115 kW, efficiency 92%. As additional options, it is equipped with auto-ignition, burner self-cleaning, and remote control. Hopper capacity is 810 liters, fuel is supplied by two augers. Can burn any biomass with a fraction not exceeding 40 mm. The 115 kW model has a huge weight of 1150 kg, which increases the flooring and transport requirements.

Cost: 450,000-477,000 rubles.

Universal models

Boilers using any solid fuel: all types of coal, peat, firewood, wood waste, seed husks, briquettes with varying efficiency, but structurally designed for long-term combustion. They are much cheaper than specialized ones, but also much less effective and practical when working with sawdust.

Tis Pro DR

Excellent inexpensive universal boiler. Furnace steel 5 mm thick is used as a heat exchanger, which is a very good indicator in terms of reliability and durability. It also features a huge firebox; depending on the power, the volume of the combustion chamber can be 80-116 liters. Does not use fan pressure and is non-volatile. Available in 17, 22 and 27 kW versions, efficiency reaches 82%.

Owners often note that the design of the grate is extremely practical: they are separate, cast iron (reliable and easily replaceable). No deficiencies were found due to operating practices.

Cost: 58,500-72,000 rubles.

PEREKO KSP Duo

High-tech Polish universal TT boiler of the highest price category. The innovative burner allows high-quality combustion of fine-grained fuel from eco-peas to oats as efficiently as possible. A water-filled grate in the combustion chamber makes it possible to burn wood and its waste.

Equipped with automation controlled by the ST-480 controller, which, in addition to controlling the central heating and hot water pumps, the boost fan, can also control the operation of the mixing valve and take into account signals from room and street temperature sensors. Available in power variations: 12, 18, 26, 36, 52 kW. In addition to the price, the disadvantages are large dimensions, weight and low permissible operating pressure - only 1.5 bar.

Cost: 283,000-498,000 rubles.

LIEPSNELĖ L20U

Universal Lithuanian long-burning shaft-type boiler with a power of 20 kW. The fuel is coal, pressed briquettes from coal, peat, wood waste, sawdust and other raw materials. The efficiency reaches 91%, but this is only when heating with low-ash coal; when using sawdust and wood chips, the efficiency will be lower. The heat exchanger is cast iron, in a steel casing. The boiler is known for its reliability, quality of alloys used and assembly. Even when using sawdust and wood chips, the burning time of one load can be achieved in 2-3 days.

The only drawbacks, as in the previous case, are the low operating pressure of 1.5 bar and heavy weight.

Cost: 110,000-125,000 rubles.

Calculation of the minimum required power

Determining the minimum heating power required to ensure a comfortable stay begins with the user making decisions about:

• number of circuits (housing heating, hot water supply, underfloor heating).
• region of residence (local climate, wind rose, etc.).
• number of floors, wall material, ceiling height, area and number of windows of the building.

Using the standards and coefficients of SNiP 2.04.01-85, using our and other examples, a fairly accurate calculation can be made.

In practice, in the initial calculations, the total area of ​​the heated building is determined and, based on the norm of 1 kW of heat per 10 m2, the required power spent on heating is obtained, then 20% is added for the DHW circuit and another 20% for possible inaccuracies and the creation of a safety margin .

For industrial buildings, it is necessary to make an individual calculation taking into account all correction factors.
Date: September 25, 2022