Pellet burners - purpose and operating principle

About the pellet burner

A pellet burner is a special heating device that produces heat by burning pellets or fuel granules in a boiler. In some cases, these burners use unnecessary dry grain.

There are manual and automatic burners; in automatic burners, fuel is supplied to the combustion hopper using a special auger, and the entire process is controlled by sensors, due to which the device requires minimal control from the user. Pellet burners have found their use not only in everyday life, but also in industry. They are used for space heating, water heating and to meet a number of other needs.

Pellets, or fuel granules, are a special solid fuel that is obtained from wood or agricultural waste by pressing and granulating under high temperatures.

Pellets are an environmentally friendly type of fuel, since when they are burned, the same amount of carbon dioxide is released into the atmosphere as is formed during the natural decomposition of wood

In countries where agriculture and the woodworking industry occupy leading positions, the cost of pellet fuel is much lower than that of coal. The only exceptions are those regions in close proximity to which coal mining enterprises are located.

When burning pellets, hazardous fumes are not released, as happens when burning liquid fuel.

Pellet burners RV: design, advantages, principle of operation

Pellet heating boilers are reliable solid fuel units that burn compressed sawdust in the form of granules (pellets).

These pellets are made from waste from the wood processing industry, and their combustion is 1.5 times more efficient than burning wood.

In this article we will look at the design of pellet burners.

Design of a pellet burner RV

An RV pellet burner is a device for burning pellets in a solid fuel boiler in automatic mode. The main blocks of a pellet burner are:

1. Burner mounted on the boiler.
2. Bunker for storing pellets.
3. Screw conveyor for supplying fuel from the hopper to the burner.
4. Automatic control system for monitoring the combustion process and maintaining a given temperature.

Operating principle of the RV pellet burner

Pellets or other bulk fuel are poured into a bunker, the capacity of which affects the duration of autonomous operation without additional fuel loading.

The fuel is lifted from the bunker to the burner by a screw conveyor. Fuel is taken from the bottom of the bunker and pellets enter the burner through plastic pipes.

Read how to choose the right automatic solid fuel boiler for long burning. When the boiler is installed, take care of temperature control to achieve an ideal indoor microclimate. Read more here.

To ensure safe operation of a solid fuel boiler, install smoke exhausters, cyclones and ash collectors. Read more about these devices at the link.

The burner is a grate on which the combustion process occurs. The burner is equipped with an automatic ignition system, and the combustion process is controlled using photocells.

To supply the required amount of air, the pellet burner is equipped with a fan.

The process of fuel supply, ignition, air supply and combustion are controlled by the control unit in automatic mode.

The set of pellet burners RV includes:

1. Burner.
2. Bunker.
3. Screw conveyor.
4. Control block.
5. Fuel supply pipeline.
6. Temperature sensor.
7. Thermal insulating sleeve.
8. Clamps.
9. Required wires.
10. Passport and description of the equipment.

Advantages of RV pellet burners:

• High level of automation.
• Safe operation.
• Automatic ignition and flame control.
• Presence of fuel spill protection.
• Easy installation, dismantling and cleaning.
• System self-diagnosis.
• The design of the burner will prevent the fuel from igniting in the bunker.
• The bunker allows the boiler to operate autonomously for up to 30 days.

Disadvantages of RV pellet burners:

• Pellet burners are quite expensive.
• Pellet heating is more expensive than gas heating.
• Many imported models of pellet burners are not designed for operation in severe frost conditions.

Features of pellet burners

Some types of pellet burners (series “TA” and “MA” from “KST” and “KMT”) are equipped with an additional compressor for automatic pneumatic cleaning of ash accumulation on the grate.

It is also possible to install a GSM module, which allows you to control the pellet burner remotely. Access can be obtained via a mobile device. To protect against unauthorized access, the system is password protected.

It is possible to install an air temperature control sensor and program a weekly operating mode.

Is a gas water heater spoiling the interior of your kitchen? No problem. Our article will help you successfully fit a gas water heater into your kitchen design. Do you want to have hot water, but don't want to buy a water heater? You can kill two birds with one stone with the help of a double-circuit boiler: it will provide both heating and water supply. Read more here.

Have you decided to go with a gas boiler, but the assortment in the store makes your eyes wide open? We have prepared for you a review article about the leading manufacturers of gas equipment.

Taking into account all the latest modernizations, pellet boilers are becoming an independent intelligent heating system, capable of automatically monitoring the safe operation of the equipment. In the event of an emergency, a message will be sent to your mobile phone.

Burner brands

GreenEcoTherm GP 25-32-45; OBSCHEMASH RV; Lidmash PV; Megatherm MPB 50; Ferroli Sun P; QUEMADOR DE BIOMASA; BMax; CONORD.

Using pellet boilers is convenient, especially in comparison with analogues. The operation of the unit is almost completely automated and does not require outside intervention, and the protection system ensures reliable and safe operation.

Principle of operation

All pellet installations that can be purchased in the store are equipped with additional components:

• Auger – supplies fuel from the bunker to the combustion chamber;
• Controllers for automating the work process;
• Bunker – the place where the fuel is located before being supplied to the combustion chamber;
• A lambda probe is a special sensor that monitors the oxygen content in smoke chambers and independently controls the fuel combustion process depending on conditions.

The pellet burner must be protected with a plastic corrugated pipe. It acts as a fuse when reverse draft occurs. If the fire begins to move towards the bunker, the pipe burns out, preventing the flame from spreading.

Additionally, a fan is used, which enhances the combustion of pellets by pumping air, as well as a thermoelectric heater, which allows the fuel to be ignited without human intervention.

In automated devices, pellets are fed into the combustion chamber automatically; a person is only required to monitor the amount of fuel in the bunker. The need to supply fuel to the combustion chamber is determined using temperature sensors (they can monitor the air temperature in the room, the water temperature, or any other environmental indicators depending on the operating mode of the equipment).

The required temperature of the coolant is set by the user, all further increases and decreases are controlled using automated equipment. As soon as the temperature reaches the set level, the burner begins to operate in standby mode (the pellets do not go out, they begin to smolder). If the temperature, on the contrary, drops, the controller activates the built-in fan. Under the influence of air, the pellets flare up and the burner goes into operating mode. If during downtime the pellets go out for any reason, the heating element is activated, which re-ignites.

Instructions for assembling a pellet boiler with your own hands

A pellet boiler with automatic fuel supply requires virtually no control over its operation. But along with all the positive aspects, it has one significant drawback - high cost. Therefore, the idea to make a similar heating device arose from the moment pellet boilers appeared on the market.

How a pellet boiler works: principle and components

The main fuel for boilers of this type are pellets - granules made from wood waste.
The general principle of the structure is shown in the figure. Fuel from the storage tank (1) is fed into the combustion chamber (2) using a transport auger. Since there is no direct source of natural draft in the boiler, a burner (3) is provided in the design to maintain the combustion process. It functions as an air blower using a fan and ignites pellets when the boiler starts operating. Next, the thermal energy is transferred through a heat exchanger to the system coolant, and residual flue gases are removed through the chimney.

The advantage of pellets is the low content of mineral elements that form ash. Its removal occurs through the grates into the ash pan chamber (4). As the fuel burns, the temperature in the combustion chamber drops - this is recorded by a sensor and pellets are supplied from the storage using an auger. The principle of operation is described in more detail in this article.

At first glance, the system is quite complex. However, with the proper desire and skill, you can do it yourself. To do this, you will need to draw up a project, select materials and tools, and also decide on ready-made components for the boiler.

Manufacturing

Since a pellet boiler is a rather complex structure, at the first stage of its creation it is necessary to draw up a project. It must contain all the necessary drawings, components and the order of their assembly. It is not recommended to make a device “on a whim” - there is a high probability of error.

For manufacturing you will need the following materials and components.

Burner

It is best to purchase a ready-made pellet burner. This is one of the most expensive components of the future boiler. The average cost of a 30 kW device is 40-45 thousand rubles.

However, doing it yourself is very problematic. The burner is not just a container for igniting fuel, but also performs the functions of controlling and regulating the flame. Using temperature sensors and several installed programs for its regulation, you can achieve optimal pellet consumption with a stable, comfortable temperature in the house.

Boiler

Experts recommend making the boiler body horizontal. This will make it possible to use the heat from the fuel as efficiently as possible. This form is due to the fact that it will be problematic to make a practical gas afterburning chamber. The boiler must consist of the following parts:

1. Frame. Depending on the material chosen, this can be sheet steel, cast iron or brickwork. The latter is preferable, since this design will retain heat and ensure its maximum transfer to the next element.
2. Heat exchanger. It is installed inside the housing and can consist of several connected pipes of the home heating system.

The boiler design must include: a combustion chamber, an ash pan and a chimney. The diameter of the hole for the combustion chamber is made according to the parameters of the selected burner. In all other respects, it is completely similar to a standard boiler or stove.

Fuel bunker

This is the storage place for pellets, from where they should be supplied to the burner. In factory models, this process is organized using augers, which gradually add fuel to the boiler as needed.

For self-production, you will need a screw (2) with a diameter of 75 or 100 mm, an outer metal casing (1) and an electric motor (3), which is connected to the burner control unit. Any design can serve as a container, from a steel conical hopper to standard pellet packaging. The inlet pipe of the auger is installed in the unloading neck of the container. A plastic corrugated pipe is mounted on its other part, through which pellets will be supplied to the burner. When a signal is received from the burner, the electric motor starts and runs until the combustion chamber of the boiler is filled with the required amount of fuel.

The result should be a complex of individual elements that together make up an effective pellet boiler. However, self-production will not always be more profitable than purchasing a factory model. To do this, you should first calculate the full estimate of the necessary materials, costs for welder services, etc. If in the end the amount is significantly lower than the finished complex, you can safely start making it yourself.

Device

Any burner has one goal - creating a powerful flame to heat the air or water jacket of the boiler. At the same time, the combustion power itself can be adjusted independently.

A pellet burner has similar goals. The device is a wind tunnel into which solid fuel is supplied and air is pumped for combustion. Fuel is supplied to the pipe using a special screw-type conveyor. The fuel itself is located in the loading hopper before combustion. The bunker can have a different volume, and it depends on the volume how long the burner can burn on its own without human intervention (adding fuel).

Pellet burner structure: 1 - The pellet enters the burner under the influence of gravity; 2 - Air enters the burner due to the vacuum created by the draft of the chimney; 3 - Pellet combustion occurs in the combustion chamber, which is called the “basket”; 4 - Due to the high temperature, thermal decomposition of wood occurs in the basket, which forms a flow of flammable gases; 5 - A secondary air flow passes under the basket; 6 - In the burner nozzle, the flow of combustible gases and secondary air mixes, forming a torch; 7 - Solid combustion products are ejected from the burner into the ash pan of the boiler or furnace by a stream of secondary air; 8 - Ventilation of the supply channel does not allow hot gases to diffuse up the channel and destroy the pellets, ensuring a stable supply of pellets.

Air is forced into the combustion zone by means of a fan.

The combustion chamber in the burner can be round or rectangular. Round burners are the most common due to their ease of manufacture. A pipe connection is attached to the outside of the combustion chamber, through which fuel is supplied from the conveyor.

The design also includes an ash pit in which combustion waste accumulates. During the combustion of pellets, a little ash is formed, so you need to clean the ash pan no more than once a week when the burner is actively used.

Torch pellet burner: manufacturing

Unlike a gravity burner, a flare burner is equipped with a screw conveyor, a fan and an electronic controller, which significantly increases the material costs of manufacturing the unit. Despite this, this design has become widespread due to the following advantages:

• High performance;
• Unpretentiousness to the quality of the granules used;
• Possibility of working in autonomous mode, while the duration of operation is determined solely by the capacity of the fuel bunker;
• High degree of fire safety.

To make a fecal pellet burner with your own hands, you will need to purchase:

• Low-speed electric motor (or two, depending on the design of the feed mechanism);
• A fan that will provide forced air supply to the combustion chamber;
• An electronic controller that monitors changes in coolant temperature and sends corresponding signals to the actuators of the device.

As for the manufacturing process itself, it is much more complicated than the manufacturing process of a gravity burner, since it becomes necessary to install temperature sensors and connect an electronic control system. The materials for manufacturing the unit do not differ from the previous version.

Heating with pellets: profitable or not, myths and reviews

Let's consider the most common questions regarding the benefits of heating with pellets, their pros and cons:

• Pellets burn better than firewood, is it really possible that something is added to them and this makes them less environmentally friendly? In fact, this is a fairly common and also erroneous opinion. As mentioned above, only harmless raw materials are used for the production of fuel pellets. For example, substances that do not pose a threat to human health are also used as binders for wood waste.

Answering specifically the question of why pellets burn better than firewood, first of all you need to say this:

Is heating with pellets profitable?

• The density of fuel granules (pellets) is an order of magnitude higher than that of wood;
• The humidity of pellets is lower.

In addition, the structure of the pellets itself contributes to their better combustion. Do not forget that pellets are burned in boilers specially designed for this purpose, with forced air supply.

How many pellets do you need to heat a house?

• You need much less pellets than firewood to heat the same room. Indeed, heating with pellets shows good results in terms of calorific value. For example, just one kilogram of pellets can produce about 5 kW of heat per hour. Considering that to comfortably heat 10 sq/m you need only 1 kW of heat, then with five kilowatts you can heat a small house of 50 square meters.

Heating boiler using pellets

• Will pellets burn in a regular stove or boiler? Without a heating boiler with forced air supply into the combustion chamber, it is quite difficult to use fuel pellets for heating. They will burn, but then we can’t talk about any savings, and the combustion of pellets, in this case, will largely depend on how good the draft in the chimney is.
• Pellets can be stored as much as you like, anywhere, and in any conditions. No, this opinion is wrong, and there are a number of strict requirements for storing pellets. Firstly, pellets are afraid of moisture, which, when it comes into contact with them, is successfully absorbed by the granules, after which they also crumble into pieces and become unsuitable for use. Therefore, pellets should only be stored in dry rooms, avoiding sudden temperature changes in them, in order to avoid the formation of condensation.

Gray or white pellets - which is better?

• 5. Which pellets are better, white or gray? This question is also a common misconception among those who decide to switch to pellet heating.

The color of fuel pellets has nothing to do with their quality, which can only be determined after burning a certain amount of this fuel. And, nevertheless, there are clear visual signs of identifying high-quality and low-quality pellets. So, for example, high-quality pellets should be free of cracks, have a length of at least 7 mm, shine in the light and not crumble if you try to lightly rub them in the palm of your hand.

We recommend: A simple wiring diagram for a solid fuel boiler with a heat accumulator

Retort pellet burner: manufacturing

The supply of granular fuel in such devices, as well as in flare devices, is carried out using a screw conveyor. The difference is that the granules are fed from below. The air required for combustion is forced through special holes in the walls of the retort. For the effective operation of such a device, a controller is required that promptly responds to changes in coolant temperature and makes the necessary adjustments to the operation of the auger and fan.

Unlike flare devices, the flame in a retort pellet burner is directed upward, so the design of the heat exchanger for these units is very different. The disadvantages of retort systems include:

• Possibility of frequent clogging of the air duct openings, leading to attenuation of the device;
• The need to manually clean the retort from combustion products and granulated fuel residues;
• No gaps in the supply of granules. If reverse draft occurs, the possibility of ignition of the pellets in the bunker remains.

Heat-resistant steel and cast iron can be used as the material for the bowl. In some models, the retort can be made of ceramic concrete or fireclay.

The complexity of manufacturing such a device at home is quite high, since in addition to plumbing and welding work, skills in connecting electronic control systems will be required.

Do-it-yourself automation for a pellet burner

The most difficult stage in the manufacture of a pellet burner is the manufacture and installation of electronic control modules. If we consider this issue from a theoretical point of view, if you have special knowledge, you can make a controller yourself, but in practice this is almost impossible. In addition, the cost of components will reduce cost savings to a minimum, and the result may be very questionable. Therefore, even if you make your own burners, controller, sensors and other automation, it is better to purchase them in a specialized store.

For efficient operation of the burner, the automation must provide:

• Dosage of pellet supply and control of the screw conveyor;
• Automatic ignition and extinguishing;
• Adjusting the air supply by changing the fan speed;
• Estimation of the amount of coolant in the heating circuit;
• Control of coolant temperature in the boiler water jacket;
• Assessment of draft parameters in the chimney.

Failure to comply with even one of these conditions can lead to failure of not only the heating boiler, but also the entire heating system.

Making a pellet burner is a labor-intensive and responsible process, however, if you have the necessary knowledge and equipment, it is quite possible to make such a device yourself. Particular attention should be paid to the selection of parameters and installation of electronic control systems; the efficiency of the boiler will depend on the correctness of their operation.

Gravity pellet burners

Such designs are easier to handle. Their great advantage is their ability to operate even without power supply. The principle of operation of the device is to pour pallets into the firebox under their own weight. The behemoth pellet burner and the pelletron pellet burner are prominent representatives of gravity products. You can put them into operation by adjusting the supply damper and the draft regulator on the chimney. The disadvantage of the design is that the pellets in the bunker can ignite.

To solve the fire hazard issue, manufacturers install thermal dampers on burners of this type. When the flame breaks out from the hearth and moves towards the bunker, a special gateway comes into play. It is heat activated. The airlock serves as a fire barrier. Another protection option is a double grate. This is a simple mechanism consisting of two parts. The upper one approaches the pellets and picks up a certain amount of them. Then the part moves towards the flame. The second part begins to dump ash into the receiver.

Advice! For a double grate it is also recommended to install a fire sluice. The mechanism may jam, and the fire will penetrate the pellets loaded into the hopper.

Types of burners

Pellet burners have several types. Reviewing them will allow you to decide which one is best suited for certain conditions. In most cases, a pellet burner requires electricity to operate, which powers the pellet feed mechanisms. Is there anything that can be done if it often disappears?

With forced fence

Such pellet burners are considered one of the best in terms of fire safety; they are used, for example, in Teplodar boilers. But for a burner with such a mechanism you will have to pay a considerable amount, which easily reaches 3 thousand US dollars. Burners with forced intake have several mechanisms through which pellets are supplied. One of them involves the use of a pneumatic system, and the second - an auger. Safety is ensured due to the fact that the channel through which the pellets move goes from bottom to top. Fire is known to move in the opposite direction, so it is unlikely that it will enter the bunker. The pneumatic system for the pellet burner has maximum safety. This is true, because the pellets are supplied in portions and do not remain in the pipe through which they move. For burners with a pneumatic feed system, large hoppers can be installed, which are loaded no more than once a month.

Screw feed mechanisms for pellet burners, for example, Teplodar, consist of two main units. One of them is an auger, which takes pellets from the bunker. He pours the material into another receiver, from which another auger lifts the pellets directly into the burner. In this case, the fire from the burner still reaches the mass. This is due to the fact that the pellets are located along the entire length of the auger. To further secure the mechanism, engineers make a unit that fits the burner from a material that melts and self-extinguishes. It acts as a fuse to cut off the path of fire.

Note! In some cases, in forced-feed systems, hoppers are installed on the boiler. This solution becomes rational from the point of view of saving space, but is no longer so fireproof.

One of the disadvantages of forced-feed pellet mechanisms, such as Telpodar, is their dependence on the availability of electrical energy. If it disappears, the supply of pellets will stop and the heating system may fail. Two electric motors have to be powered. If there are no problems with power fluctuations in your area, then you can purchase additional air boost. It allows you to increase the efficiency of pellet combustion, and accordingly increase the efficiency of the entire system. Mechanisms with a retort are becoming more common. The Fire Chalice has shown to be problematic when it crashes. In this case, the bowl itself became clogged and frequent cleaning was required. In retort burners, the combustion of pellets and pyrolysis gas occurs in the burner itself.

Note! The pellet burner controller will help to automate the process as much as possible with the choice of temperature and the amount of pellet supply. It collects data from sensors and issues the necessary commands to the mechanisms.

Gravitational

The gravity feeding device of the pellet mechanism is much easier to use. Also, such a device can function without electricity. The bottom line is that the pellets fall under their own weight. Domestic manufacturers of such burners are Pelletron and Begemot. You can start the product from Pelletron and Behemoth by simply adjusting the supply damper and the draft regulator on the chimney. But the disadvantages of the burners from Behemoth and Pelletron are the high probability of ignition of the pellets that are in the bunker. This is due to the fact that the hopper itself is fixed to the hole through which pellets are supplied to the burner. The efficiency of such pellet products is less than that of those with forced feeding.

To solve the fire hazard issue, manufacturers try to install special thermal dampers on such pellet appliances. If a flame escapes from the hearth and moves towards the bunker with pellets, then the heating triggers a special gateway, which simply blocks the movement corridor. Another interesting method of protection is the double grate. It is a simple mechanism. Its upper part approaches the hopper and takes the required number of pellets. After this, it moves to the combustion zone with pellets. The second part at this moment dumps the ash into the receiver, from where it can be cleaned.

Note! The double grate also requires a fire sluice. This is due to the possibility of the mechanism jamming and fire jumping to the pellets in the bunker.

Making a burner with your own hands

How to make a pellet burner? The combustion chamber is made of steel pipe. Wall thickness – 4 mm no less. The steel is heat-resistant and can withstand high temperatures. Attachment to the boiler unit body is carried out using a flange plate. For manufacturing you will need 3 mm steel. It is better to buy a conveyor for feeding pellets or use an auger.

To rotate the mechanism, you need bearings, a low-speed motor (electric) and a gearbox. A fan for supplying air can be purchased at the store. It is fixed on the plastic, in which the place has already been prepared. The plate is made based on the drawing. The configuration depends on the boiler door itself. A drawing of the burner can be seen in this photo.

A mandatory step is to adjust the amount of incoming pellets and air. Without this, the device will work unstably or constantly at full power. To change the intensity of the fan and auger, you can install a manual regulator. In this case, you will have to constantly monitor and adjust the burner, taking into account the temperature of the coolant and air.

It is important that during various work processes, fuel and air are correctly selected. Only then will the torch be even and stable. To do this, you cannot do without an automated device. You will need a control unit. The burner controller has free control contacts, to which the electric motor from the screw and fan is connected.

To automate the ignition of pellets and control the flame, you cannot do without a photosensor and an electric incandescent element. A photo sensor monitors the appearance of a stable flame and notifies the controller. It will turn off the filament element. But an incandescent element is needed to ignite the pellets. The supply pipe is equipped with a filling sensor. It stops feeding pellets when the auger and top pipe are full.

DIY assembly

When making a pellet burner with your own hands, it is important to pay special attention to the basket. Often, due to improper implementation, pellets can get stuck. In this case, the combustion process does not follow the required algorithm and the fire returns to the bunker. To eliminate this drawback, you need to look at the upper right part of the figure below. The slot through which the pellets will be supplied does not need to be made solid. It should have holes that are 2 mm smaller than the pellets themselves. It is also worth paying attention to the gap between the bottom of the basket and the back wall. It should be at least 6 mm, but 2 mm smaller than the size of the pellets. The unit where the pellet combustion chamber is separated from the pyrolysis gas combustion chamber must be made with continuous slits. If the burner is designed for a boiler with an area of ​​150 m2, then the height of the secondary air channels that pass under the bottom of the basket should be 30 mm.

Note! The consumption of the pellet burner mechanism, which is shown in the drawing, is about 3 kilograms of pellets per hour.

In addition to the basket, a scrupulous approach also requires a bunker in which the pellets will be stored. The problems begin with those pellet bins that are made by eye and according to a loose drawing. On the left in the diagram above are the dimensions and drawings of the hoppers that are used in Pelletrons. With a home area of ​​150 m2, one such bunker is enough for a day. At the bottom right in the same figure is a drawing and dimensions of the combustion chamber. The basis for them was the Pelletron 15 pellet burner. The corridor through which the secondary air will move is best done in the shape of the letter “L”. This is necessary for better mixing of secondary air with pyrolysis gases. This will increase the efficiency of the installation. The combustion chamber will require a special type of steel that can withstand high temperatures. At the same time, welding it at home can only be done with spot welding, since a conventional welding machine will have difficulty warming it up. You will need sheets with a minimum thickness of 2 mm. An interesting design of a pellet burner is shown in the video below.

Advice! To simplify the task of igniting a pellet burner, you can install a small fan that is powered by 12 volts, for example, a large computer cooler will do.

Description of operating modes

The very principle of operation of a pellet burner is as follows: a portion of fuel enters the chamber, it is ignited and the minimum air supply is turned on. As the fuel burns and the chamber warms up, more air is forced in. As a result, a stable, even flame appears, heating the heat exchanger with water. In factory burner devices, the process is fully automated, ignition is provided by an electric incandescent element, and its operation is controlled by a photosensor. The amount of air and pellets supplied to the chamber is regulated by an electronic unit, receiving signals from temperature and pressure sensors. A diagram of a pellet burner will help you understand how the device works.

Fuel in the form of wood pellets or seed husks can be supplied to the pellet burner auger in various ways:

• The traditional method is to supply pellets from a separate large hopper so that its capacity is enough for at least 7 days of operation of the boiler, which needs to be cleaned once a week. From the bunker, the fuel is moved to the burner device by an additional screw conveyor of the required length.
• A DIY gravity pellet burner can be equipped with a simpler fuel supply. In it, husks and granules are poured under their own weight into an auger from a hopper installed directly above the burner device, which delivers the required amount into the combustion chamber. Then the power reserve of the boiler will be from 1 to 3 days, depending on the intensity of work.

Product structure

Let's look at what main parts a homemade pellet burner consists of. Its task is to ensure uniform combustion of fuel and stability of the flame, due to which the water jacket of the boiler unit is heated. Particular attention is paid to the possibility of adjusting the combustion intensity.

The pellet burner consists of the following elements

:

• combustion chamber (in the form of a round or rectangular pipe);
• loading hopper for fuel;
• screw conveyor for supplying bulk fuel;
• fan for forcing air into the combustion chamber.

The volume of the loading hopper determines how often the boiler operating in automatic mode will have to be serviced. The operation of the blower fan is regulated by an electronic control unit - the intensity of the air supply affects the rate of fuel combustion.

Electricity is required to operate the electronic unit, fan and screw conveyor, so this burner device is energy dependent.

Principle of operation

The pellet stove is equipped with a burner that works according to the following principle

:

1. The first portion of fuel entering the combustion chamber is ignited with minimal air supply.
2. During the combustion of the first portion of fuel, the air supply increases, the flame intensifies and warms up the combustion chamber.
3. The fuel supply begins in small portions, the air pressure stabilizes, and the flame becomes even.
4. Operation of the burner in a stable mode allows for economical fuel consumption and efficient heating of the water jacket of the boiler unit.

Design Features

The combustion chamber, made of a round or square pipe, has a tray inside for burning fuel, and on top there is a pipe with a screw conveyor for dosed supply of sawdust, granules or other fine-grained energy carriers. The chamber is attached to a flange plate, which is adjacent from the outside to the front plane of the boiler unit.

The natural flow of air does not make it possible to burn fuel in a suitable mode, so a fan is installed, turning the combustion chamber into a wind tunnel.

Dry bulk fuel with optimal air supply burns with virtually no residue. The flow of forced air carries a small amount of ash into the ash pan - that is, the combustion chamber cleans itself during operation. It is necessary to remove ashes from the ash pit once every 7-10 days - the frequency depends on the intensity of the accumulation of unburned residues. If the fuel moisture content is high, the ash pan must be cleaned more often.

Organizing the supply of bulk fuel to a homemade pellet burner is carried out in two ways

:

• A large hopper is installed in the room, into which fuel is loaded for 7-10 days of continuous operation of the boiler (it is with this frequency that the burner ash pan needs to be cleaned). To supply fuel to the burner nozzle, it is necessary to install a screw conveyor, the length of which depends on the distance between the hopper and the boiler.
• The hopper is mounted directly on the pellet burner so that bulk fuel enters the burner auger under its own weight. A gravity pellet burner is simpler and cheaper to manufacture, but it will have to be serviced more often - usually a hopper is used, the volume of which is enough for 1-3 days of boiler operation.

Positive Features

A do-it-yourself sawdust burner is a device that helps expand the functionality of a conventional solid fuel boiler. Its installation allows you to save firewood and coal if inexpensive or free waste from wood processing or crop production is available. This approach will significantly reduce the overall heating costs of a private house, cottage or garage.

Pellet burners have a number of advantages, including

:

• economical fuel consumption;
• minimum amount of ash and harmful emissions into the atmosphere due to optimization of the combustion mode - fuel and combustible gases burn almost completely;
• little need for maintenance - fuel is added no more than once a day, the ash pan is cleaned no more than once a week, the operation of the unit is automated.

Pellet burner device

Automation tools

The ratio of air and fuel supply to the combustion chamber must be adjusted, otherwise the operation of the burner device will be unstable or at maximum power all the time. The easiest way to change the speed of the auger and fan motors is to install a simple manual regulator. But then inconveniences will arise in the form of constant supervision and adjustment of the heating unit depending on the temperature of the coolant and the surrounding air. Self-adjusting a pellet burner involves selecting the ratio of air and fuel in different operating modes, at which the flame will be even and stable. Device automation will help achieve this.

Pellet burner with hopper

First you will need to buy an electronic control unit. If your boiler is already equipped with one, then explore the possibility of using it. As a rule, controllers from leading manufacturers have free control contacts to which fan and auger motors can be connected. In this case, based on sensor signals, the controller will increase or decrease the supply of pellets and regulate the fan speed.

In terms of ignition and flame control, a homemade pellet burner made by yourself can also be automated. You need to buy an electric incandescent element and a photosensor. The first will turn on at the very beginning, igniting the fuel, and the second, when a stable flame appears, will signal this to the controller, which will turn off the glow element.

A filling sensor can be installed on the supply pipe; its role is to send an impulse to the electronic unit when the auger and the upper pipe are filled with fuel to stop the supply of pellets. All these automation means allow you to effectively burn pellets and create a certain comfort when servicing the heating installation. However, there are some disadvantages here:

• A homemade pellet burner cannot be connected to every controller.
• The existing electronic unit of the heating unit is often not suitable for working with ignition and burner control devices, then you will have to buy a new one.
• The cost of manufacturing the device increases.

Good article on the topic: How to make a sawdust boiler

How to correctly calculate boiler power

Before you start making boilers with your own hands, find out what area you are going to heat with their help. Knowing the condition of the heated room and the average annual temperatures outside will allow you to accurately calculate the required boiler power. Therefore, having measured the length, width and height, calculate the area of ​​the walls, ceiling, windows, and floor.

Diagram of a hot water boiler using pellets.

Then, using the reference book, determine the heat transfer resistance coefficients of the materials from which they are made. Divide the difference between indoor and outdoor temperatures by the R-value. Finally, multiplying the surface area by the resulting value and summing this data will give you the total amount of heat loss in the room. The power of your boiler should be 10-15% higher than these losses. If all this is very difficult for you, then use the Internet and find a calculator that will very quickly make all the calculations you need.

To make a boiler you will need:

Materials:

Operating diagram of pellet heating boiler No. 2.

• carbon steel, sheet 3 and 6 mm thick;
• square steel pipes with a wall thickness of 4 mm;
• 2" round pipes, wall thickness 4 mm;
• sheet asbestos;
• asbestos sealing cord;
• electrodes;
• rod (circle 20 mm);
• grate;
• fireclay brick for the combustion chamber;
• oven doors 2 pcs. (you can make them yourself from a corner and a steel sheet, in this case you only need hinges and a latch);
• electric motor for auger;
• fan;
• pellet burner (due to the complexity of the design, it is better to purchase a ready-made one; it is quite expensive, but the costs quickly pay off).

Tools:

• tape measure or ruler;
• Bulgarian;
• welding machine;
• drill.

How to choose a pellet burner

When choosing a burner device, pay attention to technical characteristics, productivity, degree of automation, etc. It would be a good idea to study the reviews of the owners, and you should take into account not only positive, but also negative comments.

The following recommendations will help you make the right choice:

• Manufacturer - burner devices from European manufacturers are approximately 2 times more expensive than their Russian counterparts. The highest quality products are offered by Kiturami, Ferroli and the German concerns VIESSMANN and BUDERUS. Domestic-made burners are unpretentious in terms of pellet quality and are fully adapted to Russian operating realities. Products are offered by the following manufacturers: Pelletron, Teplodar, Svetlodar and Obshchemmash.
• Automation – there is a certain degree of automation in each burner, but for ease of operation, it is optimal to use systems with a self-cleaning function and an installed flame attenuation controller. A burner with automatic cleaning (as in Svetlobor models) can operate without human intervention for about a month.
• Type of ignition - mechanical and electrical ignition of pellets is used. In the first case, when ignition is carried out, the owner will need to press the button several times and hold it until the boiler starts working. In the second case, simply press the start key. The automation independently controls the combustion process and automatically ignites the pellets if the flame dies out.

A high-quality burner allows you to save significantly by reducing the cost of pellets and optimizing the combustion process. Choosing the right model is quite simple, thanks to the large range of products from domestic and foreign manufacturers.

Review of popular domestic manufacturers

The products of the domestic brand PELLETRON are distinguished by their simplest design and low cost. They are absolutely independent of electricity and work perfectly in the presence of good natural draft. That is, to achieve maximum power of the burner device, the vacuum in the boiler furnace must be 20 Pa, which can only be ensured by a properly constructed chimney. An atmospheric pellet burner for a solid fuel boiler Pelletron-15 can be installed on almost any unit with your own hands; you just need to cut a rectangular opening in the loading door. The product is inserted into it and secured to the door with screws from the inside; grates and other parts are removed from the firebox space. They can be returned to their place at any time if necessary.

Thus, the advantages of the model also include low weight and ease of installation. However, there are also disadvantages:

• There is no automatic ignition system; for this you need to use a special cylinder with flammable liquid and a nozzle.
• Power is adjusted manually.
• High demands on the natural draft force of the chimney.
• The power of the product is limited to 15 kW; the design of the Pelletron-15 pellet burner using conventional draft does not allow its use in more powerful boilers.
• The manufacturer requires cleaning the chamber and grilles once a day.

Pellet burner apg 25 teplodar

Another product from a domestic manufacturer is the APG 25 Teplodar pellet burner. From the name you can judge the power of the device - 25 kW, the control range is from 5 to 25 kW. The principle of operation is a torch burner device with forced pressurization and automatic supply of pellets from the hopper. Ignition is carried out by an incandescent element, the process is completely controlled by the controller.

Design and principle of operation

The main elements of a pellet boiler are:

• pellet burner - can be retort or torch.
  The retort is made in the form of a conical bowl, granules are fed into it from below, and combustion air is forced by a fan through the side holes in the retort. The column of fire in the retort burner is directed upward; this should be taken into account when designing. A flare burner is a pipe, from one end of which fuel is supplied, and from the other there emerges a column of flame directed horizontally. Air injection occurs from the pellet supply side.
• fuel bunker - serves for loading pellets; the tank volume of 200-300 liters ensures uninterrupted operation for 3 days.
• transport belt with auger - used to supply pellets from the hopper to the combustion chamber.
• boiler body - made of steel, cast iron or brick. Inside the housing there is a heat exchanger, which consists of interconnected pipes.
• automation - granule supply controller, automatic ignition system, flame presence sensor, draft sensor, temperature sensor.

Pellet fuel, which is compressed granules approximately 10 mm in size, is made from various types of environmentally friendly materials - sawdust, peat, cake, bark.

Types of pellets

The pellets are poured into the fuel hopper, then, using an auger screw, they are conveyed through a conveyor into the pre-firebox, and from there, through an internal auger, they reach the burner nozzle. Automatic ignition occurs and the granules burn, releasing thermal energy. After the combustion of the granules, the ash goes into the ash pan, which must be cleaned from time to time.

Brief overview of imported products

A foreign alternative to domestic products is the Kiturami pellet burner , the list of its characteristics is as follows:

• power range – from 8 to 33 kW;
• Product efficiency is up to 95%, the overall efficiency value depends on the design of the boiler;
• remote controller;
• sensors for temperature, water level, overheating, overflow of auger with granules;
• self-cleaning grate.

The disadvantages of this device are its high cost and dependence on the reliability of the power supply. Otherwise, the product is quite reliable and does not cause any complaints; it is equipped with DRAGON KRP solid fuel installations.

Ferroli pellet burner

The Ferroli Sun P7 and Sun P12 pellet burner, which is installed on solid fuel units BUDERUS and SFL, is no less highly reliable. Maximum power is 34 and 55 kW, respectively, the set of options is the same as that of the previous manufacturer. The fan is a centrifugal type that provides a sufficient amount of air.

The imported Pelltech pellet burner has a wide range of available capacities, from 20 kW (Pelltech PV-20) to 1 MW (Pelltech PV-1000). It works well in conjunction with VIESSMANN boilers; the latter’s delivery package includes, as an option, a gas cleaning unit with a smoke exhauster; it is needed for installations with a power of over 200 kW.

Advantages and disadvantages

The equipment has a number of advantages:

• Pellets are a safe fuel compared to gas and electricity;
• Allows you to significantly reduce space heating costs compared to using electric boilers. At the same time, pellet installations are more expensive than gas equipment, but do not forget that it is not always possible to supply gas and purchase gas cylinders;
• Homemade installations guarantee high efficiency - 95%. Some store installations are over 97%;
• They are used not only for heating the room, but also for producing hot water;
• There are no rules for transporting and storing fuel. When near a person, pellets do not cause allergic reactions, and there are no toxic fumes when burning;
• Fuel is available for purchase. Equipment owners complained about the lack of fuel and the need to prepare a supply of pellets from the winter when the devices appeared; now there is no need to store a large volume of pellets at home; if necessary, they can be bought everywhere;
• The price of pellets is on average at the same level, unlike gas and electricity, the tariffs for which periodically experience seasonal fluctuations;
• Installation of the device does not require special skills, and there is no need to coordinate the installation with authorized bodies;
• After combustion of pellets, natural mineral ash is formed, which does not require special rules for disposal.

Along with the advantages of such equipment, there are also a number of disadvantages:

• High cost of ready-made store equipment. Despite the popularization of devices in recent years and some reduction in prices, pellet boilers are still more expensive than gas or electric equipment of similar power;
• The equipment requires constant maintenance (especially outdated models). The user will have to clean the ash pan and heat exchanger from accumulated ash once a week. In modern models, cleaning is provided at an automatic level;
• In the absence of automatic fuel supply, the user has to load pellets into the bunker manually;
• It is necessary to ensure minimum humidity conditions in the rooms in which pellets will be stored awaiting use;
• Imported equipment is practically not designed for the conditions of the harsh domestic winter, as a result of which breakdowns and malfunctions often occur;
• In remote areas, fuel for the winter still has to be stored due to the instability of supplies.

Comparison with similar devices

The cost of electricity, as well as gas, is constantly growing, which means that pellet stoves are profitable to buy, first of all, from the point of view of benefits.

We recommend: Why the pressure in the heating boiler drops: common causes of malfunctions and solutions to them

Since they are completely independent of external sources, the system’s dependence on suppliers automatically disappears - the home owner himself decides how much pellets he needs to purchase, for example, for one winter season.

Main differences

The main difference between fireplaces using wood pellets and stoves using dry wood is that they do not emit carbon dioxide. When wood burns, it releases carbon dioxide, and this is very dangerous for the health of the inhabitants of a country house. The ash that is formed after the combustion of pellets can be used as fertilizer on the site or in the greenhouse.

Another distinctive feature of such devices is that they can be installed in homes when there is no gas pipeline nearby or the possibility of heating using an electric unit. Moreover, even if both gas and electricity are available, if they are turned off, the pellet stove will be a backup system for heating the cottage. This is especially true in extreme cold. With proper operation of such furnaces and timely maintenance work, they can last more than 20 years.

Institutional use

The popularity of installing pellet stoves in restaurants, shopping centers, industrial premises, hotels and social institutions (hospitals, schools, kindergartens) is understandable.

The fact is that compared to gas heating, heating rooms with pellets is approximately 2 times cheaper, and if we talk about electric heating, the economic benefits can increase by 3-4 times.