Heating boilers for pellets (wood pellets). What is a pellet boiler

Gas is the most economical fuel. However, it should be noted that the arrangement of the centralized gas heating not always feasible. Compressed wood biofuel - pellets - is becoming a worthy alternative to gas fuel.

Pellet heating boilers - safe, environmentally friendly and cost-effective heat supply country house, a cottage or a small country house.

The device and principle of operation of pellet heating boilers

A pellet boiler is a device that runs on a special solid fuel - pellets. Granules are made from wood waste (shavings, sawdust, straw, sunflower husks and buckwheat) by pressing. Fuel granules are produced in sizes: diameter - 5-10 mm, length - up to 7 cm. When burning, 1 kg of pellets releases 4500 Kcal - this is enough for heating rooms of various areas.

Modern "pellet makers" are equipped with an automatic fuel loading system - this increases the period autonomous work boiler up to several weeks.

Pellet boilers are composed of three different mechanisms, combined into a single functional device... Usually, this is the boiler itself, equipped with a pellet burner, a storage bin for pellets and a mechanism for supplying fuel to the combustion chamber.

Pellet boiler design

Designations in the figure:

1 - pellet suction turbine;

2 - container for pellets;

3 - screw metering fuel supply;

4 - rotary valve;

5 - combustion screw;

7 - grill with brushes for cleaning;

8 - screws for ash removal;

9 - removable tank for ash;

10 - stainless steel combustion chamber;

11 - heat exchanger with a return water temperature controller;

12 - heat exchanger with built-in automatic cleaning function;

13 - oxygen sensor in outgoing flue gases;

14 - smoke exhauster;

15 - mixer valve;

16 - circulation pumping unit;

17 - valve for switching between water supply / heating systems;

18 - outlet to the heating system;

19 - branch to the water supply system;

20 - outlet from heating / water supply systems;

21 - combustion air supply.

The pellet boiler works according to the following principle. The granules are poured into the fuel tank, which are fed into the boiler furnace with the help of screws. Pellets burn, emit thermal energy going to heat the coolant in the heating system. The combustion products in the firebox rise and transfer heat through the walls of the heat exchanger, after which they leave the cooled form through the chimney. The heat exchanger is made of steel (provides strength, but needs anti-corrosion treatment) and cast iron (does not rust, but is not resistant to thermal shock).

Pellet boilers have a high efficiency - 70-90% depending on the class of equipment - medium / premium. The service life of the heating device is 10-50 years

Advantages and disadvantages of pellet boilers

Automatic pellet boilers are characterized by the following advantages:

The economy of the consumed fuel. The pressed fuel burns out without residue. The consumption of pellets depends on the quality / composition of the pellets and the class of the boiler. By weight, the heating device consumes 2 times less fuel than a wood-burning boiler.
Energy independence. The boilers can be operated without electricity. Some models are equipped with electrical equipment, but in most cases such units are completely non-volatile.
Less space is required to store fuel.
It is enough to clean the boiler furnace once a month. By comparison, a wood-fired boiler needs cleaning almost every day.
Pellets are cheaper than firewood.
Pellet boilers are environmentally friendly equipment, as they operate on natural fuel, burning wood without residue.
Pellet equipment is cheaper than gas and electric boilers.
The boiler can function without human intervention for a week.
Additional heating of the water supply can be installed.

The funds spent on the purchase and installation of a pellet boiler will pay off in 1-2 years. Subsequent fuel savings are in the tens of thousands

The inconvenience of using pellet boilers is that periodically it is necessary to load pellets supplied in bags into them, and also to clean the heat exchanger and ash collector.

Important! Despite the fact that the construction of a chimney is not required when installing a pellet boiler, it is still necessary to equip a hole in the wall or ceiling. It will be needed if there is no electricity in the house and the fan stops.

Types of pellet boilers

Pellet heating equipment can be conditionally divided into three groups:

The pellet boilers themselves use exclusively wood chips pellets as fuel. In such a device, retor-type burners are used.
Conventionally, combined boilers operate on biogranules, but if necessary, firewood and briquettes can be used as "spare" raw materials. Alternative fuel can be fired for a short time. In such boilers, the firebox is arranged in a special way- the standard grate can be removed.
Universal boilers operate on any solid fuel. Typically, the unit has several combustion chambers (separate for each energy carrier). To change the fuel, it is enough to remove the pellet burner, and the device is ready to work on traditional solid fuel.

By the type of pellet burner, boilers are divided into two types: retor and flare types. Flare burners are used in combined boilers and have the following advantages:

simplicity and versatility of installation in different types boilers;
reliability of the device.

Flare burners are less powerful than retor burners and, accordingly, have lower efficiency.

Characteristics of retor type pellet boilers:

the possibility of thermoregulation;
high power;
only use pellet granules, which it is advisable to stock up at once for the entire season.

Let's consider some models of pellet boilers from different manufacturers.

South Korean firm Kiturami produces two popular models of pellet boilers: Kiturami KRP 20-A and Kiturami Premium. The heating equipment of this company has the following characteristics:

boilers have a fuel overflow protection mechanism;
no condensation forms on the walls of the heat exchanger, due to the exact correspondence of the operating time circulation pump and burners;
Availability automatic system cleaning grate;
an additional solenoid valve ensures a high level of fire safety.

Distinctive features of Kiturami Premium:

efficiency level - 94%;
improved bunker;
electronic control of the burner;
the fuel bunker holds 160 kg;
pellet consumption - 5.5 kg / h;
warranty period - 2 years;
cost - about $ 4300.

Kiturami KRP 20-A has the following characteristics:

the boiler is used not only for heating, but also for providing the house with hot water;
automatic dosage of fuel;
ease of installation and cleaning of equipment from ash;
built-in frost / overheating protection;
boiler power - 24 kW;
capacity of the pellet hopper - 160 kg;
fuel consumption - 5.5 kg / h;
cost - $ 3600.

Domestic company "Teplodar" manufactures the Cooper OK-15 boiler with the following characteristics:

use of different fuels (coal, firewood, pellets);
you can install a gas burner;
fuel ignition - mechanical;
The efficiency reaches - 94%;
device power -15 kW;
capacity of the bunker for loading fuel - 200 liters;
fuel consumption -1-5 kg / h;
the cost of the boiler is 1100 USD.

When choosing a pellet boiler, you can follow these recommendations:

An important selection criterion is the boiler power and heat loss at home. You can adhere to the formula: 1 kW * h of heat = 10 sq. M.
Decide on the type of pellet boiler - specialized (firebox with only pellets) or universal.
Choosing a pellet boiler, it is necessary to provide a supply of pellets for the entire heating season.
Before purchasing a boiler, it is necessary to study the operation of the control unit. It is important that the control system is docked with the automation. Not all models of pellet boilers have inputs for connecting additional sensors or external systems management.
It is necessary to make sure that the company's service department has all the necessary spare parts for the purchased model of the boiler. The company must issue a guarantee certificate and a quality certificate for the pellet boiler.

You can make a pellet boiler yourself. There is a lot of information on the net on how to calculate, design and assemble heating in a house. But is it worth doing? Pellet boiler is a highly efficient device that guarantees uninterrupted and safe heating

Installation of pellet boilers

Boiler connection diagram

The system of heating / hot water supply of a house using a pellet boiler provides for the installation of a storage tank.

Pellet boiler: connection diagram

1 - Supply of pellets to the storage. The volume of the storage bin is about 4.5 sq.m. - this is enough to heat one private house for one family.

2 - Connection of the storage with a pellet boiler. The granules are fed automatically.

3 - Connecting the boiler to an intermediate heat storage tank.

4 - Circulation of the coolant through the heating and hot water system.

Requirements for the room for installing the boiler

For the installation of pellet boilers, the following conditions must be met:

Optimal base for the boiler - concrete screed, with a height of about 5-10 cm. Such a floor facilitates cleaning and maintenance of the boiler.
For heating small house the boiler can be installed in the house itself. If there is not enough space for the equipment, then the boiler is placed in a special boiler room or in a garage next to residential building... In this case, pipes from the boiler to the house are laid underground at a depth below the level of soil freezing. The pipe must have good thermal insulation.
An important condition for the normal operation of the boiler is the evenness of the base. The device provides for compliance with the vertical position.
The room should be kept at a temperature not lower than +10 C °, humidity about 40%.
It is necessary to equip near the device separate place for storage of wood pellets.
The boiler room must have ventilation. The boiler chimney is led out through the roof of the building.

Installation steps

Let's consider step by step how to install a pellet boiler:

Important! It is better to entrust the collection, installation, adjustment of the pellet boiler to a technician specializing in such operations.

Boiler commissioning

Before starting up the automatic pellet boiler, check:

compliance of the heating system with the project;
tightness of the chimney, hopper and boiler;
whether the heating system is full, the pressure in the system;
operability of control devices.

The sequence of turning on the pellet boiler:

Fill the hopper with fuel.
Check the water pressure level in the system.
Open the smoke damper.
Ignition to the burners - carried out through the control panel or manually.

The boiler is turned off after the remaining fuel has burned out. Burnout can be observed through small holes in the flap of the upper door of the device. At the end of the heating season, the boiler must be cleaned of soot / ash, and the burner socket must be disconnected from the electrical network.

Pellet boiler operation: video

In many regions, the problem of heating private houses is still relevant. Of course, on modern market a huge range of equipment is presented that uses a wide variety of materials as fuel, be it gas, wood, electricity or oil, etc. However, access to gas pipelines and stable power grids is far from everywhere, so solid fuel heating remains the most preferable in many regions.

One of the best options for a solid fuel heating unit is a pellet boiler that you can assemble yourself.

The unit in question is one of the modifications of an ordinary solid fuel boiler, optimized for operation using special pressed pellets as fuel.

The used pellets are very low-cost fuel, inferior in this indicator only to the main gas.
By assembling a pellet boiler, you can provide economical and efficient heating of your own home.
In addition, pellet boilers are one of the most safe species heating equipment for private use.

The principle of operation of a pellet boiler

As noted, such boilers use pellets as fuel, that is, pellets from pressed wood chips, sawdust and other similar waste.

The operation of the boiler is based on an extremely simple principle. You load the pellets into a special hopper, from there they go through the auger in small portions to the burner, in which the pellets are burned.

Under the influence of the flame, water is heated in a special tank connected to the heating system.

As a result, you get reliable, environmentally friendly and highly efficient heating at the lowest cost.

Boiler advantages

Among the many advantages of pellet boilers, one should note their durability. Units made of steel serve up to 15-20 years without any problems without the need overhaul... If the boiler is assembled using cast iron, the durability indicator increases up to 50 years.

If desired, you can assemble both a non-volatile model of a pellet boiler, which does not require connection to the mains, and a full-fledged automated unit. In this regard, be guided by your requests and preferences.

Boiler assembly manual

Pellet boilers have enough complex structure... Instructions for assembling them will also be difficult and multi-stage. For greater convenience, the assembly process for each main unit is considered separately. Buy or make the items you need, and then simply assemble them into a single system.

This element of the pellet boiler is highly recommended to buy ready-made. It is on the burner that you will spend the most money.

Self-production the burner is practically impossible for the reason that this part of the boiler is not just a container for igniting the loaded pellets, but a complex control and regulation mechanism.

Pellet burners are equipped with special sensors and have several pre-installed programs that allow you to achieve the most rational fuel consumption and ensure the most efficient heating of the house.

Housing and heat exchanger

You can handle the assembly of the case and the manufacture of the heat exchanger yourself. It is best to make the boiler body horizontal - with this arrangement of the unit, the maximum heating efficiency is achieved.

For the manufacture of the case, it is recommended to use fireclay bricks. You simply assemble a kind of box without a top cover and place a heat exchanger with pipes and other elements connected in it. Brick is recommended for the reason that it accumulates heat much more efficiently than cast iron, steel sheets and other popular materials.

The heat exchanger of a pellet boiler is a system of pipes interconnected and connected to the heating pipes of a private house.

First step. Assemble a heat exchanger from square pipes rectangular... To do this, cut the pipes into pieces of the desired length and weld them into a single structure.

Second step. Make holes in the profile serving as a vertical post for connecting round pipes.

Step three. Prepare holes in the remaining front pipes for the water outlet and connection pipes. Hot water will be discharged through the upper hole, cold - fed from the bottom.

Use metal pipes length from 150 mm. Then it will be possible to use polypropylene pipes... Be sure to install ball valves in the places where pipes are connected to the boiler. Additionally, you can install filters if necessary.

Fourth step. Weld the rear of the unit to the front and weld the side pipes.

At the same stage, choose a convenient place for connecting a chimney with a diameter of 10 cm. At the bottom of the heating unit, provide a small chamber for collecting ash. Also, the design of the pellet boiler necessarily includes a firebox. About him further.

Toplivnik

In the firebox, as already noted, pellets are stored and from here they are fed to the burner.

First step. Prepare necessary materials and fixtures. You will need an auger with a diameter of 7.5 or 10 cm, an electric motor and a metal casing. Connect the engine to the pellet burner control unit.

Any container of suitable volume with sufficiently thick walls can perform the function of a metal casing.

Second step. Install the inlet of your auger into the outlet of the casing. To the other part of the auger, connect the corrugated plastic pipe for feeding granular fuel to the burner.

The burner sends a signal to the electric motor - it starts the auger - the combustion chamber of the pellet boiler is filled with the required amount of pellets.

In the end, you just have to collect all the listed elements into a single structure. Do this and proceed to installing the boiler.

Boiler installation

At this stage, you have to take care of the arrangement of the boiler room and the smoke exhaust system.

The floor and walls of the boiler room must be made of non-combustible material. The floor can be made of concrete. Pave it with ceramic tiles, if desired.

Place the boiler on a strictly level surface. Choose a place so that the distance from the front side of the unit to the nearest wall is at least 100 cm. Choose the distance from the rest of the walls so that in the future it is convenient for you to carry out preventive work, maintenance and repair of the equipment.

It is important that the air temperature in the boiler room does not fall below + 8- + 10 degrees.

Pay special attention to the issues of arranging the smoke exhaust system. Not only the efficiency of the homemade pellet boiler, but also the safety of the residents of the house directly depends on the correctness and quality of the chimney.

In most cases, a pipe with a diameter of 10-11 cm is sufficient for efficient smoke extraction. It is important that the pipe diameter slightly exceeds the diameter of the opening for smoke extraction from the heating unit. The more powerful the boiler, the more massive the pipe should be.

Choose the length of the chimney so that it rises above the roof of the building by at least 50 cm, better - more.

Use a sealed pipe to make the chimney. It is important that the pipe material does not support combustion and withstands high temperatures.

The chimney must be insulated. To protect the pipe from atmospheric precipitation install a protective cone on it.

In the lower part chimney make a hole to drain the condensation. For more convenience, you can connect a tap to the hole. Also prepare a hole to clean the soot from the pipe.

Boiler start-up and maintenance

Running

The equipment can be started only after installing the pellet boiler and connecting the corresponding pipes of the heating system to it. After the mentioned tasks are completed, turn on the feed cold water into the heating system.

Observe the boiler operation. If you have any abnormal symptoms, turn off the equipment and do not use it until troubleshooting.

Care

Homemade pellet boilers, like any other heating units, need proper care.

Clean the ashtray from waste every 2-3 weeks. Clean the flue gas duct every 2-4 weeks. This will not take you long, but ignoring such simple maintenance will significantly reduce the efficiency of the boiler and make the equipment potentially unsafe.

If desired, you can connect to the pellet boiler additional funds automation. This will make the operation of the equipment more convenient - you can simply forget about the need to reload fuel and other related activities for a while.

Modern automation tools even make it possible to establish remote control of the heating unit, which is also very convenient.

And these are not the only possible additions. How do you, for example, self-cleaning systems for boilers? Be sure to check the available modifications and, if you wish, buy such add-ons for your boiler.

You can assemble a simple pellet boiler with your own hands, following the instructions received earlier.

Happy work!

Video - Pellet heating boilers

Video - The principle of operation of a pellet boiler

Pellet heating systems create healthy competition for others heating systems... Primarily due to environmental friendliness and economy. Even though high cost such equipment, it can pay for itself in just two to three years. But if you make a pellet boiler with your own hands, then the savings increase several times.

The principle of operation and features of the device

The device of pellet boilers includes a screw structure for supplying fuel and an ignition mechanism that ensures rapid ignition of the pellets. The system also includes a fan that provides forced air supply. This greatly improves the combustion process.

The ignition is only triggered when the fuel present in the stove has ignited well. In automatic mode, pellets are fed into the firebox as needed. Combustion leads to the formation of hot gases, which, passing through the chimney, give up up to 95% of the useful heat.

The air flow is automatically regulated based on the optimal parameters of the boiler. Human participation in the entire process of work is not required. Control, if necessary, can be carried out remotely from the console.

An important feature is that the fuel is supplied only until the maximum required temperature is reached. Its supply will be resumed only after the temperature drops to minimum values.

And the advantages of pellet stoves include:

small volume of the combustion chamber;
the bulk of the heat (up to 70%) is removed in the structure itself;
very high efficiency factor, reaching 96%;
if the device is equipped with an additional water supply circuit, then the heat obtained can be used, for example, for heating rooms.

There are different types of pellet boilers:

1. Boilers operating exclusively on wood pellets.
2. Combined models that can work not only on pellets, but also, if necessary, on wood or coal.
3. Universal, capable of operating on almost any type of solid fuel.

The pricing policy is different. So, the most expensive options will be universal furnaces / boilers, which, due to the ability to use different types of fuel, have a more complex design.

DIY pellet boiler 3h

Advantages and disadvantages

It is not enough to draw up a correct diagram and know the device of the unit for a full-fledged weighed decision to create a homemade stove operating on pressed wood waste. It is also necessary to take into account all the advantages and disadvantages of the design.

The main positive aspects include:

The advantages include the following feature of pellet stoves, as absence unpleasant odors and black smoke, which makes the design environmentally friendly.

Pellet boiler with their hands - challenge!

But such units also have unpleasant sides that must also be taken into account when drawing up a diagram of heating equipment.

high cost of imported components for self assembly ovens;
due to the fact that it is not very developed, it becomes difficult to buy fuel;
to automate the process, you will have to additionally take into account the cost of electricity, since all automation equipment runs on electricity.

When the unit is stopped for more than 10 hours, it is necessary to carry out a new setting.

You also have to think about the power source. To avoid unexpected power outages, it would be better to install an autonomous generator.

DIY pellet boiler 5h

Self-production

When there is a question about choosing a pellet boiler, it is worth considering two important factor... The first one involves the use of a ready-made factory version. But here you have to come to terms with the fact that the design will not be adapted to individual conditions. And so you have to adjust the environment for him.

The situation is completely different with homemade options... After all, a pellet boiler with your own hands can be made, taking into account all the nuances of specific conditions. And thus, create an aggregate that fully matches the requests.

If the fuel itself is confusing, then it is useful to understand that pellets are a product of recycled wood and agricultural waste with high heat generation efficiency and economic benefits.

Does not harm such fuel and environment, insofar as:

no air pollution;
does not require fuel procurement, which means cutting down trees;
the vapors are completely free of harmful substances.

But you need to know that the pellets will have to be stored in accordance with certain rules, since they are extremely flammable, and this can cause a fire.

It is worth mentioning the durability of such installations. After all, a self-assembled steel model can serve without repair for 15-20 years. If cast iron is used as a material, then these figures increase to 50 years. And this is an almost eternal device that can serve a person reliably for many years.

homemade pellet boiler with a capacity of 50 kW

Taking into account the requests and desires, the design of pellet stoves can be either completely autonomous, without being connected to the mains, or automated, using systems that monitor the operation of the device.

And having already carefully weighed and thought over everything, you can make a decision whether to make a pellet boiler with your own hands or still buy a ready-made copy

Assembly guide

When making pellet boilers with your own hands, you need to take into account that the main structure consists of several main parts. But it is preferable to make each of these parts separately from the entire unit. Therefore, the future furnace is conventionally divided into: a burner, a body with a heat exchanger, a firebox, a screw mechanism and a bunker.

Based on this, you can start creating separate parts, which may have different design features and drawings. It all depends on the chosen model and individual requirements.

Burner device

The most the best material for the manufacture of the burner is steel and cast iron. This part of the oven is inserted directly into the unit. And the principle of work and its specifications may differ depending on many parameters. That is why this part is designed and assembled separately.

In order for the part obtained in the process to comply with all safety standards, you will have to contact a specialist for verification. After all, only a person competent in this area is able to qualitatively assess the reliability and safety of the device, taking into account all the nuances of the specifics.

Recommended to equip homemade burner ignition system, which can be either manual or automatic. In the second version, a fan is additionally used.

A flare burner compares favorably with other prototypes. Although she does not have high power, but due to its small size it will be the best option for a home oven.

If you want to buy this particular part of the pellet boiler because of the apparent complexity, then you should first think about it, since a finished factory burner will cost about 75,000 rubles. Although the price can be influenced by: performance, type of ignition, dimensions and materials used. Therefore, the price may be more or less. But if you apply the existing drawings, then it will be much easier to assemble such a structure with your own hands than it might seem.

Do not forget that the burner must correspond to the type of the boiler itself. To create drawings, you can contact a specialist who will help you draw up a project taking into account all the nuances.

A properly assembled burner can last 10-15 years. The service life of factory analogues reaches 20 years.

Installation of a budget pellet burner // FORUMHOUSE

Housing and heat exchanger

It is recommended to use cast iron or fireclay brick as a material for creating the body, as it is resistant to high temperatures, drops and overheating.

The heat exchanger is made of steel pipes square shape with a wall thickness of 4-6 mm. But do not forget that pipes will subsequently be welded to the ends. round shape.

Service doors must be installed in the front and rear walls. And from the tools you will need welding machine and a drill.

According to the drawings, the heat exchanger is located inside the boiler.

Description of the firebox

You can buy a firebox, or you can do it yourself. To do this, you need heat-resistant steel with a thickness of 5 mm or more. For the doors, you need the same steel, but with a thickness of 6 mm. The grate is also made of heat-resistant steel, but with a thickness of 1 cm.

The firebox will be used to supply fuel to the boiler. Its size should not be very large, but sufficient to load pellets for two to three days of burning at a time.

Of the tools you will need: a welding machine, a grinder, a tape measure and a drill.

Hopper and auger

To make a pellet hopper with your own hands, you need a square-shaped metal profile and steel sheets.

A frame of the required shape and size is welded from the profiles. Steel sheets are cut according to a template and pre-welded to the frame. Now you need to weld the lower part together, making it look like a funnel.

Weld on the bottom of the funnel metal profiles so that the cut-to-size steel sheet can pass freely. This will be the gate for controlling the pellet feed.

Here, a kind of box of the same steel sheets is welded in such a way that a container is obtained, where the pellets will subsequently be located. A round hole is cut on one side, where a piece of pipe is welded at an upward slope.

Now all that remains is to paint the resulting structure well.

The auger is chosen so that it can pass freely enough into the opening of the firebox. Since it will be in constant contact with a high temperature, it, like the firebox, must be selected from heat-resistant steel. The dimensions will depend on the individual parameters that are taken into account when drawing up the scheme.

Boiler installation

To install the boiler, you will have to equip a separate room and a high-quality chimney. The best option would be a room measuring 2.4 by 2 meters. It is preferable to cover the walls with a non-flammable material that washes well. After all, there will be constant dust and debris from the fuel that can settle on the walls.

In the pellet storage room, you will have to equip a place with pallets that can withstand heavy weight... A separate element will be ventilation, which also needs to be done efficiently.

The walls of the room should not be heated above 120 degrees. Therefore, if the covering is made of non-combustible material, then the distance to the boiler should be at least two centimeters. The boiler is placed at a distance of three centimeters or more from the plastered wall, and the walls, which are not covered with anything, should be at least 10 cm from the stove.

The chimney is made of stainless steel 3-4 mm thick. Its height should be from 6 meters, and the structure itself should withstand temperatures up to 600 degrees.

It is quite possible to make a pellet stove with your own hands. It does not require repair, is environmentally friendly and easy to use. A correctly sized and assembled unit is safe and effective remedy heating. In addition, your own design of the heating device will save a considerable amount.

Today, the range of heating equipment, as well as types of fuel, is very diverse, which allows you to choose the best option for any requirement. Pellet boilers are of great interest. They are essentially modified versions of wood fuel stoves.

However, in comparison with the latter, these installations have a much more improved design, differ high level automation and high efficiency. Their appearance is due to the creation of granular wood fuel - pellets. And, despite the short time of existence, these boilers have already proven themselves from the most advantageous side.

The standard structure of a pellet boiler is a complex of interconnected mechanisms located in a single body and united common system automation:

combustion process mechanism: boiler with burner, fan, controller, heat exchanger and other related elements;
fuel supply mechanism: tank and screw conveyor.

The pellet tank can be either external or built-in. Their purpose is one - to ensure a systematic uniform flow of granules into the furnace. Bunkers have different sizes: the larger models allow the loading of large volumes of fuel, due to which the boiler can function without interruption for several days. The granules are fed by means of a screw conveyor. Heat exchangers can be made of cast iron or steel.

Imported models are most often equipped with cast-iron devices. They are not susceptible to the development of corrosion, are characterized by good heat transfer, but they are heavy and react slowly to change. temperature regime... Steel heat exchangers are mainly used in domestic boilers. They are distinguished by faster heat transfer, are lightweight, resistant to temperature differences but are prone to corrosion. However, in order to avoid the latter, more and more manufacturers are covering heat exchange elements with anti-corrosion compounds. Perfect option- heat exchangers made of non-ferrous metals, but such boilers are distinguished by a high price.

The burners are of retor or flare type. The former have one significant drawback: susceptibility to heavy pollution, especially if poor quality pellets are used. They require regular cleaning. Flare varieties are devoid of this minus, so they are most often found in modern models. Pellet boilers are completely non-volatile, but some types of this equipment are equipped with electric motors as backup source nutrition. This solution allows the boiler to function even in the absence of fuel.

The principle of operation of a pellet boiler

The simplicity and reliability of the operation of pellet boilers is obvious. By means of a screw conveyor, the pellets are fed to the combustion grate, where they are ignited with the help of an ignition mechanism or an electric spiral.

Fuel combustion is accompanied by forced air supply, which is carried out by a fan. After the pellets are well heated, the ignition is automatically turned off. Hot flue gases are generated during combustion. When leaving the firebox, they envelop the heat exchanger and by convection transfer all the released heat to it.

Combustion products, of which a minimum is released during the process, enter a special ash pan. Full automation of the supply of air and fuel pellets to the combustion chamber makes it possible to fine-tune the parameters of the boiler operation and maintain them for a long period of time without human intervention. Configuration and control can be carried out from a built-in or remote control. Setting the minimum and maximum temperature limit is intended to ensure stable maintenance of the intermediate value.

In case of exceeding the maximum temperature, the fuel supply is automatically stopped, and is resumed only after the indicators fall below the minimum. Some modern models boilers are equipped with GSM or Wi-Fi transmitters, which significantly expands the capabilities remote control, and increases the safety of equipment operation.

Features of the pellet boiler

The combustion chamber of pellet boilers is not very large, with the exception of large-sized models, and up to 70% of the main heat removal is carried out in the multi-pass convective part of its structure. As a result, the temperature of the exhaust gases is 100-200 ° C. The positive displacement burners used in these boilers provide efficiency up to 95%. This indicator is significantly higher than that of other types of solid fuel boilers and, in terms of its efficiency, is comparable only to.

Some models are additionally equipped with a hot water circuit. It should be noted here that production technologies do not stand still, and today a variety of modifications of pellet boilers are presented on the market, which, despite the general concept of operation, have a number of fundamental features. In general, there are 3 main types of equipment under consideration:

pellet boilers for wood pellets;
combined boilers, which provide for the possibility of short-term operation on coal / wood;
universal pellet boilers operating on different types solid fuel.

The design features of each type are determined by the fuel used.

Video about pellet boilers, which was shown on the Russia 24 channel in the housing technology program

Advantages and disadvantages of pellet boilers

Among the undoubted advantages of these boilers:

high efficiency;
ecological cleanliness;
profitability;
durability;
simplicity, convenience and safety of operation.

In fact, the listed advantages have already been considered in the context of the article. High efficiency equipment operation is achieved through high-quality new technology boiler design and the use of environmentally friendly and affordable pelleted wood fuel. The service life of such devices is from 20 years or more, while in the combustion process no harmful substances... Full autonomy of operation and automation of the entire process greatly facilitates operation and makes pellet boilers an excellent alternative to other heating methods.

As for the shortcomings, there are not many of them. First, there is a high price tag. At the same time, it is worth noting a steady trend towards democratization. pricing policy many manufacturers. Per last years the cost of this equipment has decreased, but so far pellet boilers are more expensive than gas and electric models.

Secondly, heating by means of pellets at the moment in terms of efficiency significantly loses natural gas... Heating a small private house requires about 100 kg of pellets per day. In addition, during their storage, it is necessary to completely exclude the effect of moisture. This is where the disadvantages are exhausted. Obviously, taking into account all the advantages, the high price of these boilers is quite justified. And summarizing all of the above, we can confidently predict that the demand for this equipment in our country will only increase over time.

The problem of reducing heating costs today comes first for many categories of citizens. It especially affected the owners of private houses with an individual heating system, sewerage system and water supply. Often reasonable decision to reduce costs are boilers for heating pellets.

VIADRUS pellet boiler Ekoret with fuel tank

Boilers of this type have only recently become widespread in the homes of Russians, but due to their low price, cheap fuel and ease of maintenance, they are increasingly being installed for space heating. Below we will consider the design features and the principle on which pellet boilers work. The customer reviews, which are given in the article, will help evaluate all the pros and cons of buying a pellet pyrolysis boiler.

Pyrolysis

Pyrolysis is the decomposition of organic compounds at high temperatures. When oxygen is available, the pyrolysis process turns into normal combustion. If the access of oxygen is limited, then the hydrocarbon fuel will decompose into low-molecular combustible compounds and slag. In the case of wood pyrolysis, a mixture of gases of methyl alcohol, acetone, benzene and a small amount of other combustible substances and practically pure carbon with admixtures of metal oxides is formed.

More recently, it has been widely used as a fuel charcoal- fuel, which is obtained by burning wood without air access in coal pits. Such a traditional one leads to significant losses of thermal energy during primary combustion. A modern solid fuel pellet boiler is free from this drawback and is able to fully use the thermal energy that is generated during the pyrolysis of wood. Therefore, such a device is also called a gasifier.

The principle of operation of the pellet boiler

Boilers long burning on pellets consist of three separate mechanisms:

directly to the boiler with a burner;
a conveyor for feeding granules;

The pellet boiler functions as follows:

pellets are loaded into the fuel hopper;
pellets are fed into the boiler by a screw conveyor;
in the boiler firebox, the pellets burn out and heat the coolant.

The pellet boilers use the top-down combustion principle. In this case, combustion is much slower than in a conventional firebox, where the fuel burns "from the bottom up" and the circulating heated gas flows involve the fuel layers that are higher in the process. Structurally, this is solved as follows.

In the firebox itself there is a burner with a nozzle for supplying heated air directly to the combustion zone. Thanks to this, it becomes possible to control the rate of fuel combustion, moving the fire zone gradually downward. The supply of heated air makes it possible to burn fuel in the most complete way. In this case, ash and soot are formed in a minimum amount, and the efficiency (efficiency) of boilers operating on pellets increases to 96%.

This mechanism of operation ensures a gradual combustion of the fuel. Long-burning pellet boilers can operate on one tab for more than a day, which makes this equipment quite convenient for use in everyday life. In addition, the presence of a fuel bunker in the equipment design makes it possible to automate the operation of heating equipment as much as possible.

Construction and internal structure

Boilers for their design are similar to general scheme, according to which all solid fuel boilers... However, they have some peculiarities. For example, the size of the firebox in these models is much smaller, since their heat exchanger is heated not so much by an open flame, but by hot air in the convection channels. This allows a more complete use of thermal energy. The exhaust gas temperature in equipment of this design does not usually exceed 150 degrees Celsius.

The firebox of a pyrolysis boiler on pellets is designed with the calculation of the possibility of controlling the air supply to it. The presence of a fuel bunker allows you to control the supply of pellets to it with the ability to adjust the speed and temperature of combustion. Due to this, the possibility of regulating the heating temperature of the heat carrier in the system is achieved. Structurally, this is solved by installing a screw conveyor, which directly supplies fuel.

For the manufacture of boilers for heating pellets, high-strength steel alloys are most often used. The firebox and heat exchanger are made of corrosion-resistant cast iron. It should be noted that the service life of cast iron boilers can reach 45 years, which is much longer than the performance of equipment made of steel.
Pellet granules are ignited using a special electric heating element. A fan blows air into the furnace. After the equipment enters operating mode, the electrical circuit is disconnected. Thus, pellet boilers consume very little electricity.

Automatic operation

Modern models of boilers for long burning on pellets are necessarily equipped with automation, which feeds pellets into the furnace according to a certain program, and also turns on and off the burner to save fuel consumption and maintain a given temperature regime, which can change during the day. The control panel is located on the boiler itself or on the remote control.

A medium-sized 25 kW pellet boiler, which consumes approximately 5 kg of fuel per day, is equipped with a hopper with a volume of 250 to 350 liters. Thus, continuous completely automatic operation equipment can be carried out for at least three days. By installing an external hopper, this time can be increased even more.

External hopper design

Due to the fact that the supply of pellets to the boiler is metered, the burner does not overheat and all equipment can be turned off remotely by stopping the fuel supply. In this case, the boiler will automatically stop working after a few minutes when the loaded dose of pellet granules has completely burned out.

Equipment cost and customer reviews

In general, the price of solid fuel boilers is not the strongest point of this equipment. The fact is that pellet boilers are much more expensive, for example, gas equipment the same power. Nevertheless, the significant operational savings due to the availability and cheapness of fuel ensures high demand for it.
If we talk about the price level, then the following data can be cited. Pellet boiler Zota ( Russian production) with a capacity of 15 kW costs approximately 150 thousand rubles. The price of the most powerful one (with a capacity of 100 kW) is about 350 thousand rubles. The owners of these boilers note that the cost of one kW of thermal energy costs no more than 1 ruble. (subject to the purchase of fuel at a price of up to 4.00 rubles / kg).

A pellet boiler Grandeg (manufactured in Latvia) with a capacity of 25 kW is sold for an average of 250 thousand rubles. A 100-kilowatt boiler from the same manufacturer will cost 500 thousand.

If we analyze the reviews of the owners of this equipment, then it can be noted that they all confirm the significant efficiency of heating equipment of this type and ease of use. A pellet boiler house in one heating season will save tens of thousands of rubles on fuel alone.

In addition, pellet heating boilers are distinguished by their quiet operation and ergonomic design.
Some owners complain that this equipment needs to be connected to the mains in order to work. However, such devices consume very little electricity.

The price for pellets is about 5500 rubles per ton, i.e. one kilogram, on average it costs about 5-6 rubles. If necessary, you can set up the production of pellets by purchasing necessary equipment or by making it yourself.

The video below shows how a pellet boiler works.