Today, a large number of brands are represented on the Russian market, offering pellet boilers of various modifications and functionality.
By design, all the wealth of choice can be combined into just a few groups. To make it easier for you to make a choice, we recommend that you pay attention to just a few parameters that will give a complete understanding of whether the game is worth the candle in one or another sample under consideration.
1) Efficiency of the pellet boiler heat exchanger:
Efficiency index - directly affects your annual costs for the purchase of pellet fuel - the higher this indicator, the lower your costs.
Usually it ranges from 80 to 90%, however, there are models in which the efficiency reaches 92% due to a well-thought-out heat exchanger.
Some manufacturers offer for an additional 10-12 thousand rubles to increase the efficiency from 85 to 90-92% to purchase turbulators for their boilers, which is not the best option due to the fact that these steel elements are not durable and you will have to periodically buy new ones for those or 10 thousand.
It is better to immediately select a boiler in which a developed heat exchanger guarantees maximum efficiency without additional wear parts.
Remember, after buying a pellet boiler, your heating costs are just beginning - choose the most highly efficient models with maximum efficiency. They can be found for the same money as the most popular models with less efficiency.
2) Type of pellet boiler burner:
There are two types of burners - flare and retort. Each type has several varieties.
Let's talk briefly about flare burners: either expensive, or not of high quality and not durable. Both options do not increase the rationality of the choice. Therefore, we recommend narrowing the selection of the boiler to designs with retort burners.
Retorts are of vertical and horizontal type. In both types, there are not whimsical solutions, but this factor should be taken into account. Unpretentiousness means the ability of the burner to work on pellets of any quality without failures. There are many solutions from different manufacturers - almost all of those presented in our catalog cope with this problem.
In our opinion, horizontal tray-type retorts are more practical - in them, the risks of clogging with combustion products and emergency shutdown of the boiler are minimized.
3) Fire safety of pellet boiler:
This problem is solved in different ways, we advise you to select boilers in which the supply of pellets is organized using two screws with an air gap in the transport channel - according to statistics, boilers with such an architecture of the device feeding the pellets to the burner are the most fireproof.
If you are offered a boiler for 10-20 thousand rubles cheaper, but with a single screw feeder - think about the future ...
The described signs of a quality boiler are not exhaustive, but they will help reduce the risks of making the wrong choice to almost zero, so we recommend that you take this information into service before going to the store.
The problem of reducing heating costs today comes out on top for many categories of citizens. It especially affected the owners of private houses with an individual heating system, sewerage and water supply. Very often, pellet boilers are a smart solution to reduce costs.
Pellet boiler Ekoret from VIADRUS with a fuel bunker
Boilers of this type have only recently become widespread in the homes of Russians, but due to the low price, low cost of 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 that are given in the article will help evaluate the pros and cons of buying a pellet pyrolysis boiler.
Pyrolysis
Pyrolysis is the decomposition of organic compounds at high temperatures. With the access of oxygen, the pyrolysis process turns into ordinary combustion. If the access of oxygen is limited, then the hydrocarbon fuel will decompose into low molecular weight 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 almost pure carbon with impurities of metal oxides is formed.
More recently, charcoal has been widely used as a fuel - a fuel that is obtained by burning wood without access to air in coal pits. Such a traditional one leads to significant losses of thermal energy during primary combustion. A modern solid fuel pellet boiler is devoid of 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 gas generator.
The principle of operation of the boiler on pellets
Long-burning pellet boilers consist of three separate mechanisms:
- directly from the boiler with a burner;
- conveyor for feeding granules;
The pellet boiler operates as follows:
- pellets are loaded into the fuel bunker;
- pellets are fed into the boiler by a screw conveyor;
- pellets burn in the boiler furnace and heat up the coolant.
Pellet boilers use the top-down principle of fuel combustion. At the same time, combustion is much slower than in a conventional furnace, where the fuel burns “from bottom to top” and the circulating heated gas flows involve layers of fuel that are higher in the process. Structurally, this is solved as follows.
In the furnace 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 by moving the fire zone gradually down. The supply of heated air makes it possible to burn the fuel in the most complete way. At the same time, ash and soot are formed in a minimal amount, and the efficiency (efficiency factor) of boilers operating on pellets increases to 96%.
This mechanism of operation ensures the gradual combustion of fuel. Boilers of long burning on pellets can work on one tab for more than a day, which makes this equipment quite convenient for household use. 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 arrangement
The boilers are similar in design to the general scheme by which all solid fuel boilers are manufactured. However, they have some features. For example, the size of the furnace for 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 more complete use of thermal energy. The temperature of the exhaust gases in equipment of this design usually does not exceed 150 degrees Celsius.
The furnace of the 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, it is possible to control the heating temperature of the coolant in the system. Structurally, this is solved by installing a screw conveyor, which directly supplies fuel.
For the manufacture of boilers for heating on pellets, high-strength steel alloys are most often used. The furnace 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 with the help of a special electric heating element. Air is blown into the furnace by a fan. After the equipment enters the operating mode, the electrical circuit is turned off. Thus, pellet boilers consume very little electricity.
Automatic operation
Modern models of long-burning pellet boilers are necessarily equipped with automation that feeds pellets into the furnace according to a certain program, and also turns the burner on and off 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 with a fuel consumption of approximately 5 kg of fuel per day is equipped with a hopper with a volume of 250 to 350 liters. Thus, continuous fully automatic operation of the equipment can be carried out for at least three days. With the installation of an external hopper, this time can be further increased.
Construction of the outer bunker
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 pellets is completely burned.
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 significantly more expensive, for example, gas equipment of the same capacity. Nevertheless, significant operational savings due to the availability and cheapness of fuel provide it with a high demand.
If we talk about the price level, we can cite the following data. A 15 kW Zota pellet boiler (Russian-made) costs approximately 150 thousand rubles. The price of the most powerful (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).
The pellet boiler Grandeg (manufactured in Latvia) with a capacity of 25 kW is sold at an average of 250 thousand rubles. A 100-kilowatt boiler from the same manufacturer will cost 500 thousand rubles.
If we analyze the reviews of the owners of this equipment, it can be noted that they all confirm the significant cost-effectiveness of this type of heating equipment and ease of use. A pellet boiler house for one heating season will save tens of thousands of rubles on fuel alone.
In addition, pellet 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 of pellets is about 5500 rubles per ton, i.е. one kilogram, on average, costs about 5-6 rubles. If necessary, you can set up the production of pellets by purchasing the necessary equipment or by making it yourself.
The video below shows how a pellet boiler works.
There are many types of thermal boilers. In order for potential buyers to immediately give at least a general idea about them, the main "watershed" of the classification of units was carried out by their creators by the type of fuel used.
However, inside gas, diesel, electric (so far everything seems to be simple and clear), etc. boilers also have their own narrower subsections, already associated with other features of the work, for example, the method of loading fuel, the physical and chemical characteristics of combustion. And here it is already quite difficult to do without explanations of specialists.
In this material, we will talk about what pyrolysis boilers are, which attract with their unusually high efficiency, and what is their fundamental difference from pellet boilers, which, for some reason, do not have such a fantastic coefficient, are much more expensive.
Immediately, we note that both of these types of boilers operate on solid fuels. However, this is where their relationship ends. And the “firewood” units are devoured by different ones, and the “method of nutrition”, i.e. they have different fuel loadings, but their main difference is in the principle of obtaining heat.
So, let's figure out what happens in the "wombs" of both modifications of thermal units.
Features of the operation of pyrolysis boilers
Pyrolysis boiler (another name is gas-generating)- a thermal unit of the so-called "long-term combustion", in which the fuel is burned according to the principle of pyrolysis - the decomposition of organic matter with a lack of oxygen. At the same time, the firewood itself and the gases released during their combustion are burned in two separate chambers - in fact, independently of each other.
In pyrolysis boilers, they are located like two floors in a house, only a ceramic nozzle acts as a ceiling. Firewood burns in the upper compartment, from where the smoke exhauster pumps out air. At the same time, a gigantic temperature is pumped up (up to 800 ° C and above). Such conditions contribute to the fact that the wood does not actually burn, but chars very slowly with the release of a large amount of wood gas. This is the process of pyrolysis.
The released volatile substances (mainly hydrogen, hydrocarbons and carbon monoxide) enter the lower chamber through the nozzle through the blower installed inside the boiler. There, oxygen is mixed with the released gases, due to which all these substances burn out with maximum heat release. Its vapor rises again to the "top floor", supporting pyrolysis and providing significant heat transfer. Hence the impressive efficiency - up to 92%, and other undoubted advantages.
Advantages of the pyrolysis principle of operation of a thermal boiler
. Hygienic cleanliness - minimum ash in the combustion chamber and soot in the heat exchanger and chimney ;
. Dramatically reduced in comparison with "classic" solid fuel boilers the amount of substances hazardous to health contained in the smoke ;
. Long burning time of one bookmark, the interval between which can be up to 16 hours .
How will pellet boilers "respond"?
As the name implies, such thermal units operate on pellets, that is, compact wood pellets of a (usually) cylindrical shape.
The principle of fuel combustion is direct combustion, as in a conventional fire or fireplace. Wood pellets are burned on a special burner in a separate chamber.
Pellet boilers compare favorably with pyrolysis boilers in an extremely convenient way of supplying fuel. The main part of this sometimes unsafe work for a person is performed by automation. The owner of the boiler only pours portions of pellets into a special storage - a bunker connected to the boiler. Then the screw conveyor comes into play, which delivers the required amount of fuel pellets from the tank to the combustion chamber.
Bunkers for pellet boilers vary greatly in their capacity. So, the owner of a storage facility with a volume of 12 cubic meters (that's about 8 tons of pellets!) can make one maximum backfill and not "bother" this issue during the entire heating season! But such "hangars" in conjunction with automation significantly add to the price of all equipment, so the choice, as always, is yours - a huge "pyrolysis" efficiency or pellet "autocomfort".
According to the type of fuel used, solid fuel boilers can be divided into wood-burning(mainly intended for working with wood, wood waste, wood briquettes), pellet(using pressed granules of woodworking waste) and universal for which the main fuel is coal, but you can also load firewood, wood briquettes and peat briquettes.
In addition, there were separate models of solid fuel upper combustion devices, in which any of the listed types of solid fuels can be burned. Such boilers are equipped with three types of air distribution nozzles for a telescopic air supply pipe to the combustion zone for three groups of fuel (coal, firewood / briquettes, pellets), as well as a spark deflector to maintain more efficient combustion. Modern models are equipped with a programmer that facilitates the control of the combustion process. Naturally, such models are more expensive than traditional devices.
Read also: Principles for the selection and installation of a gas boiler
When using a solid fuel boiler, it is important strictly adhere to fuel requirements for a specific model. For example, if the device is intended for burning wood, then it is necessary to use logs of hard non-coniferous species with a moisture content of up to 20%. The use of wood with high humidity leads to underheating of the coolant during operation, to a reduction in the life of the boiler as a whole, as well as to an increase in the amount of soot and condensate in the smoke, which causes a faster clogging of the chimney. If we are talking about pellets, then the moisture content in them should not exceed 10%.
Average fuel consumption when using a solid fuel boiler in a cottage with an area of 100-200 m², it will be about 3-5 kg / h. Subject to the use of storage capacity per day, you will need approximately 12-15 kg (in the coldest time - up to 20 kg).
Combustion chamber type
AT standard solid fuel boiler the process of fuel combustion takes place, according to the principle similar to the operation of a conventional stove, where combustion is ensured by the natural flow of air. In this case, the energy received is spent on heating the coolant distributed through the pipes leading to the radiators. In some cases, the boiler can be equipped with a fan to create additional draft, which increases the efficiency of combustion. The maximum operating time on one tab of fuel in standard solid fuel boilers is 6-8 hours, so you will have to throw fuel into the combustion chamber several times a day.
Unlike traditional, pyrolysis solid fuel devices the chamber is divided into two parts. In one of them, which is called the gasification or loading chamber, the fuel slowly burns at high temperature and lack of oxygen. As a result, wood gas is released, which burns out in the second chamber (combustion chamber) located below. With such combustion, almost no soot is formed and a minimum amount of ash appears. Wood gas burns with a very pure yellow or almost white flame. These devices have a higher efficiency (up to 85%) and allow you to automatically adjust the power. The maximum combustion time of one load here is 8-12 hours, which, together with a heat accumulator, allows reducing the frequency of fuel filling up to 1-2 times a day. The disadvantages include not only a higher price compared to traditional solid fuel boilers, but also the need to use only dry firewood.
Read also: Boiler from the socket. Electric heating - an efficient alternative to gas
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Boilers that allow you to minimize the number of loads imply top burning. This is due to the fact that air is supplied to the high vertical combustion chamber by means of a telescopic tube in the upper part of the chamber. A distributor is installed at the end of the pipe, which can have a different shape for different types of fuel. Under the influence of gravity during the combustion process, the distributor goes down, providing a constant flow of air. In this case, the flame center gradually moves from top to bottom, due to which the metal fatigue factor is reduced and the service life of the device is extended. When using top burning boilers, fuel is loaded every 12-70 hours. The duration of burning here is increased both due to the large capacity of the loading furnace, and due to the fact that not the entire volume of fuel burns, but only the upper 15-20 cm - the rest is dried and waits for its turn.
Pellet solid fuel boilers usually they are a system of three components: a boiler with a burner directly, a screw feeder and a free-standing bunker with pellets. A pellet burner is installed on the boiler body, which is placed in the combustion chamber and fuel is supplied to it by an external screw. The operation of the auger is controlled by a photosensor built into the burner, which monitors the filling of the hopper with granules. After filling, the external auger is turned off, and the internal one transports the fuel to the combustion grate, where it is ignited using an electric spiral. A fan is installed under the burner to supply air to the combustion zone. The operation of the unit is automated and controlled by the control panel, which sets the necessary settings, including the required temperature, the daily cycle of the boiler, turning it on and off. For safe operation, an automatic valve is provided that breaks the electrical circuit when the equipment overheats. Pellet boilers are easy to use, the frequency of loading depends on the size of the bunker and in most cases is done once every few days.
It is rightfully considered that European pellet boilers are the best in their class of heating equipment. Although, recently several competitive Russian models have appeared, the domestic manufacturer is not yet able to create a boiler that will be identical in its parameters to the same “Germans” or “Czechs”.
European manufacturers of pellet boilers
Solid fuel pellet boilers from Europe have been available to domestic consumers for over 10 years. During this time, manufacturers have studied the Russian market well and began to offer equipment that is more adapted to the operating conditions and the wishes of customers.European heating boilers on pellets are distinguished by the following parameters:
- Profitability.
- Reliability.
- Minimal harmful emissions into the atmosphere during fuel combustion.
- Automation of the combustion process.
- Long service life.
German pellet boilers
The leading manufacturers of pellet boilers in Germany are Buderus and Viessmann. The factories of the companies produce a wide range of water-heating equipment and components necessary for the installation of heating systems. At the moment, the products of German manufacturers have no competition in terms of quality and reliability:
German pellet boilers are distinguished by traditional build quality, reliability and full compliance with the parameters specified in the technical documentation. All products are covered by a factory warranty.
Italian boilers for pellets
Italian pellet boilers are somewhat inferior in performance and reliability to their German counterparts. Favorably stand out due to the versatility of the proposed equipment. The most popular products of the following companies:
Italian manufacturers produce autonomous pellet boilers designed for simultaneous heating of heating and hot water systems, controlled by intelligent automation, operating on almost any type of fuel.
Polish pellet boilers
Boilers made in Poland are presented in the lowest price segment. At the same time, the produced equipment is reliable and productive. The most popular are two brands of equipment - Defro and Kostrzewa:
Polish pellet boilers have earned a reputation as reliable and unpretentious equipment with a high degree of automation and control.
Positive reviews about Polish boilers gradually bring Kostrzewa and Defro products into the class of the most demanded pellet equipment.
Czech pellet boilers
From the product range of Czech manufacturers, boilers manufactured at the OPOP and Benekov factories stand out in particular. In terms of performance, reliability and cost, the equipment is similar to German units:
The Czechs produce economical, distinguished by a well-thought-out design and the absence of everything superfluous, pellet boilers. In the summer, the models are able to work on heating hot water.
Austrian pellet boiler
There are not so many Austrian companies for the production of pellet boilers, but they all enjoy continued popularity due to the high efficiency of the equipment offered. The low costs of pellets, together with high heat transfer, made it possible to bring the cost of heating on pellets closer to the main gas:
Despite the initial costs, it is profitable to purchase Austrian heating equipment, due to the economical costs of pellets during operation. All overpayments will fully pay off in a few years of service.
Finnish boilers on pellets
Finnish pellet boilers are not as well known to the domestic consumer as Italian and German units. Manufacturers from Finland are mainly associated with sauna heaters and solid fuel boilers for domestic and industrial purposes:
Finland produces equipment "without frills", designed for domestic operating conditions, productive and reliable.
Pricing policy for pellet boilers from Europe
The main disadvantage that distinguishes imported pellet boilers has always been their high cost. Compared to domestic units with similar characteristics, the price is often 2-3 times higher. The average cost for boilers is as follows:- Pellet boilers from Finland for 30 kW will cost 360 thousand rubles. However, when choosing, it must be taken into account that the design does not provide for an automation system, remote control and other additional options.
- German pellet boilers for long-burning heating - for the full automation of the combustion process, a self-cleaning system and other functionality, you will have to pay up to 500 thousand rubles. (boiler for 30 kW Buderus).
- Polish-made pellet boilers - a fully autonomous 25 kW thermal power plant manufactured by Kostrzewa, will cost approximately 280-300 thousand rubles. The cost is given taking into account the simultaneous purchase of the Fuzzy Logic 2 logic control system.
- Czech-made pellet boilers - offered for about 320 thousand rubles. with the usual set. Additionally, you will need to purchase a silo to increase battery life, a controller for remote control, etc.
- Boilers for pellets from Austria - a price target from 280-320 thousand rubles. depending on the manufacturer and basic configuration. It is possible to connect a built-in tank for heating hot water (purchased separately).
The German units will cost the most. Moreover, the cost is higher than the average price level, by 150-200 thousand rubles. than other analogues.
Another country that “spoils” the domestic consumer with “cheap” products is Italy. Pellet boilers, the same FACI, for 30 kW will cost only 200 thousand rubles.
Are the "Europeans" demanding on the quality of pellets
The operating instructions expressly state that wood pellets for heating boilers must meet the following requirements:- woody origin.
- First grade.
- The maximum percentage of ash content is not higher than 2-3%.
- White color.
If you plan to use low quality pellets, it is better to choose heating equipment adapted to Russian conditions. Finnish units are suitable, as well as domestic counterparts.
Manufacturers reserve the right to refuse warranty service if it is proved that the boiler was fired with low-grade pellets.
Which pellet boiler is better, ours or imported
Why are imported pellet boilers better than analogues offered by a domestic manufacturer?- Automation of the combustion process - unfortunately, Russian manufacturers often have flaws that affect the operation of the equipment. If you take similar units from the same "Germans", the boilers work without failures.
- Thermal efficiency - fuel consumption in imported pellet boilers is 10-15% less than that of Russian counterparts. In some models, the savings are even greater through the use of modulating burners and condensing units.
- Fuel quality - in this respect, domestic units win, which are distinguished by "omnivorousness".
- Cost - European models of "western" assembly are 2-3 times more expensive than Russian products. The exception is the Italian FACI, assembled in the territory of the Russian Federation. The cost of such units is not higher than that of Russian heat generators.
