With a limited choice of energy resources, there may be no alternative to heating with wood at all. It is important to purchase a suitable wood-burning boiler and understand the features of its operation. We will tell you about these heating units, from choosing the right type to installation issues.
Main types of wood boilers
The arsenal of heating equipment is constantly replenished with new, more advanced products, but nothing radically new has been invented among solid fuel boilers. In an attempt to increase efficiency, designers improved the design one way or another, which is why several varieties appeared with a number of characteristic features:
1. Difficult Z shape firebox or its division into 2 combustion chambers. Such boilers are designed for long-term combustion and the most complete combustion of the released pyrolysis gases.
Example of a solid fuel boiler design long burning: 1 — boiler automation; 2 - loading door; 3 — primary air supply; 4 — secondary air supply; 5 - ash pan; 6 - combustion of pyrolysis gases; 7 - pyrolysis of solid fuel; 8 - heat exchanger; 9 — fan-exhaust fan
2. The presence of water-filled grates and/or jackets. It is believed that in this way the coolant absorbs up to 90% of the combustion heat, but in practice, good wood-burning boilers with an efficiency above 80% are already very rare.
3. Form of organization of blowing. By reducing the incoming oxygen, the combustion duration can be greatly extended, maintaining the water temperature within specified limits. Usually implemented through a manual or controlled damper; if the draft is not strong enough, a boost fan can be used. The damper is usually controlled by digital automation, which controls the temperature of the water in the supply pipe.
4. Type and design of heat exchanger. On the one hand, there is a race to maximize surface area for more efficient heat removal, and on the other, for durability and reliability. In the first case, we have cellular boiler-type heat exchangers, highly efficient, but problematic to clean and repair/replace. On the other hand, simple tubular coils made of cold-drawn seamless pipe are hard to argue with the classics.
5. Availability of insulation. The need for a mineral-filled casing is determined by the installation location. If it makes no sense to waste heat outside, then for a garage or workshop a non-insulated boiler can become good method heating
There are also differences in the type of fuel, horizontal and vertical arrangement shaft, as well as firebox material. Chambers and coils made of cold-rolled low-carbon steel are simple and unpretentious, but are susceptible to scale formation. Coils and water-filled jackets made of cast iron are the most durable and are not subject to scale formation, but require special piping due to their high sensitivity to thermal shock.
Equipment power
Ultimately, what is important for a boiler is not so much the details of its internal structure, but the main performance indicators, which were achieved using a number of engineering innovations. The most important and determining parameter of the boiler is its rated instantaneous power. Heat capacity y different types fuel is different, like different types of firewood, the manufacturer cannot accurately predict it and calculate the rated power in a particular operating mode.
Power is determined by two indicators. By the volume of the firebox one can judge the mass of the filling. On average, it is believed that for every kilowatt of power of a wood-burning boiler there is 2.5-3 liters of combustion chamber volume. Having received the instantaneous value of the power released during combustion, it is possible to predict what part of it can be absorbed by the heat exchanger at different temperature conditions work. Typically, absorption is deliberately made higher than the calculated heat release under combustion conditions close to optimal, but this approach is fraught with troubles.
The fact is that all wood boilers suffer from a common disease - the formation of tar due to high humidity burned wood. Condensation only occurs when the temperature difference is high enough. Thus, the formation of build-up on the economizer or secondary heat exchanger can stop when the coolant is heated to 40-45 ºС. The point here is that if you load the boiler halfway, its power will not be enough to properly heat the walls and heat exchangers, which is why the equipment will simply “leak.”
Chimney device
The main impact of condensation of water vapor from firewood falls on the chimney system. The length of the pipe is large, the temperature difference (especially outside) is very high. There are two approaches to solving this problem.
The first is to install inspection outlets to drain condensed moisture. Such outlets should be located at the lowest point of each rotating segment, starting from the last vertical section and ending with the boiler connection point. The disadvantage is that the water drainage tubes periodically need to be cleaned and cannot be of significant length with a small diameter.
With brick chimneys or asbestos-cement pipes Such problems do not arise in the lining. The difficulties of constructing such chimneys are obvious, but they can also be circumvented by using more expensive materials. We are talking about insulated sandwich pipes made of of stainless steel with mineral filler. For a chimney installation today it is - best option. To summarize: condensation does not form only in insulated chimneys.
System inertia
Another disadvantage of a solid fuel boiler is hidden in the cyclical nature of its operation and the inability to independently replenish fuel reserves. Because of this, either a high heat capacity of the house structure itself is required, or solid insulation, close to a passive house, or a way to store a reserve of heat for the period of cooling of the system.
Since the volume of the heat exchanger itself in the boiler is small, the displacement of the system can be increased mainly by increasing the diameter of the pipes. Another alternative of this kind is the installation of a heat accumulator. With the right approach, it is possible to realize heat accumulation only after heating the main system, which will help speed up the heating of the house and solve the problem with condensation.
Underfloor heating systems have their own high inertia, which increases with the thickness of the accumulating screed. With a thermal cut-off under the floor, this can be a truly long-term heat source. With a sufficiently thick layer, even the use of water at a higher temperature will not cause discomfort and thermal zebra, but along with the inertia of the system, the time it takes to reach the operating mode increases. On the other hand, connecting a heated floor to a wood-burning boiler requires a rather complex piping that prevents overheating of both the boiler and the pipes in the floor.
Automation and piping of wood-burning boilers
As already mentioned, the boiler power can be adjusted only by changing the amount of oxygen supplied. This system works most efficiently and accurately in pyrolysis-type mine boilers using wood or briquettes.
The main automation complex includes an electronic control unit, a fan, an electrically driven draft regulator and a thermocouple tightly wound to the supply pipe. All these components are sold both individually and in sets for a specific boiler model. On average, all automation costs about 4-5 thousand rubles. We should separately mention the importance of having protection against falling dampers and sealing grooves on the loading and inspection hatches, chimney, and draft stabilization system.
For solid fuel boilers, a number of other types of protective devices are provided, installed in the hydraulic piping. Among the absolutely mandatory ones are a circulation pump and protection of the firebox from overheating - a safety group for relieving excess pressure. Please note that the outlet of the relief valve must be turned towards the wall or equipped with a hose so that when activated it does not injure anyone present. Safety requirements may require the installation of a chimney bleeder valve to stabilize draft and combustion; it is mounted immediately at the outlet of the boiler or immediately before the final vertical section.
Connection diagram for a solid fuel boiler with a heat accumulator: 1 - chimney; 2 — thermostat; 3 - security group; 4 — air separator; 5 - circulation pump; 6 - heat accumulator; 7 - three-way mixer; 8 — weather-dependent automatic; 9 — heating radiator; 10 - circulation pump; eleven - check valve; 12 — expansion tank; 13 — protection against dry running; 14 — make-up valve; 15 — overhead temperature sensor; 16 - solid fuel boiler
For cast iron boilers, it is practiced to install a two-way valve that mixes water from the hot outlet to prevent cold water from entering the heated firebox. When installing a heat accumulator, a three-way electric valve is added, which starts the supply of heat to the tank only after the main composition has warmed up. Control is carried out based on the return temperature, the additional circuit is turned on 7-10 ºС before the cut-off temperature is reached. In this aspect, control units with a PID controller are most preferable.
Installation, connection
The boiler is installed on a concrete pedestal, the height of which is determined by the equilibrium hydraulic system. Ideally, the coolant in the boiler should be under the greatest pressure compared to other sections of the pipeline. The position of the boiler is also determined by the direction and point of connection of the chimney. Its connection can be either vertical (from above) or horizontal (from behind or from the side).
It is recommended to use only steel or copper pipes in the boiler piping; for plastic there is too great a risk of overheating. The section of the supply pipeline 3-5 meters from the boiler is also traditionally made of metal. The connections can be welded, or if the necessary equipment is not available, they can be threaded using tow and anaerobic sealant.
The boiler must be configured taking into account the low heating rate and high inertia. The operating temperature of the coolant is usually maintained within 50-65 ºС. In this case, the reverse hysteresis temperature should be slightly higher than the maximum at which the boost completely stops. This is necessary so that ignition begins long before the water in the system cools down more than it should.
Content- Firewood as a fuel
- Water heating boiler design
- Advantages and disadvantages of heating with wood
From time immemorial, people have used firewood to heat their homes. Since the advent alternative types fuels such as gas, diesel and electricity, they began to fade into the background, but are still one of the main types of fuel in our country. In this article we will look at a wood heating boiler, the advantages and disadvantages of using wood as a type of fuel, as well as the features of installing heating devices of this type.
Before moving on to considering wood-burning boilers with a water circuit, let's first take a closer look at this type of fuel. What is the secret of their special popularity in Russia and what are the disadvantages of using them in the heating system of your private home or dacha.
The Russian market has already emerged as a top leader among models powered by pellets. This review is dedicated to them. So let's get started.
Firewood as a fuel
As you know, firewood is parts of tree trunks intended to be burned to produce heat and light. This type fuel has become widespread in our country not by chance, because Most of it is covered with forests of various species.
Photo 1: Pine firewood for a solid fuel boiler
Coniferous and hardwood firewood have different calorific values. The former provide less heat and burn much faster. In addition, they take up more space due to their low density. Deciduous ones, on the other hand, burn hot and long. That's why, owners country houses, whenever possible, they try to harvest hardwood firewood.
Unlike oil and gas, firewood is a renewable source of energy. This feature, among others, has brought them such popularity. One cubic meter The calorific value of firewood is equal to 200 liters of oil and 200 cubic meters of gas. Another significant advantage is their low ash content in the region of 1-2%.
The disadvantages of firewood include its low calorific value compared to the same gas or coal. Another disadvantage is high humidity. The process of water evaporation steals some of the useful heat, reducing the overall heating value.
Photo 2: Installation of a hot water boiler in the boiler room country house
Preparation of firewood for the whole heating season Not simple task. A forest of a suitable species is felled, the branches are cut off and then the tree trunk is sawed into short pieces called “chocks”. Subsequently, the logs are split with a special ax called a “cleaver” into individual logs, which are then stored in woodpiles in a specially equipped place under a canopy.
In cold winters, wood is used to heat stoves in the house and bathhouse, and is also used in heating boilers central heating. Let's look at what it is, what its structure and design features are.
Return to contentsWater heating boiler design
Water heating boilers are cast iron or steel devices, by burning solid fuel in which the coolant is heated in a special tank, which in turn circulates through a closed heating system and heats the room.
Photo 3: Operating principle of a wood-burning boiler with a water circuit Wood-burning boilers are the simplest and cheapest devices you can buy from solid fuel heat generators. Structurally, they consist of the following components and assemblies:
Loading chamber
The loading chamber or firebox, as it is also called, is a compartment with a door in which a load of firewood is placed. A feature of a wood-fired boiler, unlike coal or pellet boilers, is the presence of a larger firebox, which allows it to accommodate fairly large logs.
Ash pan
The ash pit (ash pit) is located in the lower part of the heating boiler, directly under the firebox, and serves to collect solid fuel combustion products in the form of ash. To ensure cleaning, the ash pan is equipped with a door.
grate
The grate is a grate made of steel or cast iron that separates the firebox and the ash pan. Through the holes in the grate, the ash formed as a result of combustion is poured into the ash pan. Also, through these holes, air is supplied to the combustion chamber, improving draft and fueling combustion.
Heat exchanger
Structurally, a heat exchanger is a container of complex shape, inside which there is a coolant, most often water. The complexity of its shape is due to ensuring maximum heat removal inside the boiler. The variety of its designs is quite large. Each manufacturer tries to introduce its own innovation that can increase the efficiency of the boiler. The most common type of heat exchanger is a water jacket.
Chimney
During the combustion of wood in a heating device, volatile products are released that must be released into the atmosphere. The chimney in a solid fuel boiler is used for these purposes. Having given maximum energy to the coolant, volatile gases rush out through the chimney. The correct one is extremely important, because Wood combustion products contain toxic compounds and their entry into a living space can lead to dire consequences.
As you can see heating device simple Additionally, modern TT boilers use various additional devices that increase their operating efficiency, such as draft regulators, smoke exhausters, etc. There are also both single-circuit and double-circuit modifications, with the possibility of hot water supply.
Photo 4: Boiler chamber for loading firewood The operating principle of water heating boilers is as follows. The boiler is installed indoors, filled with coolant and connected to the supply and return lines heating system. A portion of firewood is loaded into the firebox and set on fire. As the wood burns, it heats the coolant, which moves through pipes to radiators in various parts of the house. Having given off heat to the premises, it returns back to the boiler, where it is heated and the process is repeated. The ash accumulates in the ash pan, from where it is then removed during the boiler cleaning process. Flue gases are discharged outside through the chimney.
For thousands of years, firewood has been the only means of heating a house. As a result of progress, firewood moved to the background; gas, electricity, and oil products took first place. However, even now there are places where it is advisable to use firewood for heating a private house.
Design and principle of operation
Despite the variety of wood-burning boilers, their design is practically the same. Any unit consists of a fuel combustion chamber, a water heat exchanger, a chimney and an ash pan. In terms of design, the simplest wood-burning boiler is a potbelly stove, where, when wood is burned, water is heated and enters the heating system. The efficiency of such equipment is low, and fuel consumption is significant. That's why modern units are equipped with a long-burning function and have a more complex structure.
Firewood is loaded into the firebox, where, when burned, it gives off heat to the heat exchanger, which is built into the boiler. Pipes designed to supply hot water to the heat exchanger are connected to common system home heating. It is equipped with radiators, expansion tank and pipes. In addition to heating the coolant, the boiler and chimney heat the room, in which they are located.
As a result of the combustion of wood, smoke is produced, which is discharged outside with the help of a chimney, and soot settles on the walls of this structure. It is worth noting that a large accumulation of soot in the chimney reduces draft and the risk of fire.
Cleaning of chimney channels is carried out thanks to special openings - closed dampers. Brushes and ruffs are used for this. Due to modern technologies special compounds are added to the fuel that, during combustion, can clean the chimney ducts from the inside.
The supply of cold water and the removal of hot water from the heat exchanger is carried out through pipes. Modern equipment equipped with automatic equipment that makes servicing a wood-burning boiler as easy as possible:
- Temperature sensor. Sends a signal to the air supply fan;
- Pressure meter. Indicates that the normal value is exceeded;
- Water pressure sensors.
The efficiency of wood boilers is affected by the type and quality of fuel. If firewood is used for heating, peat briquettes and coal should not be used. This significantly reduces the efficiency of the equipment. Also Poorly dried wood should not be used for heating– combustion produces a lot of steam and soot, as a result of which the boiler will need frequent cleaning.
Application of wood boiler
Heating houses with wood is popular in rural areas, where there is no centralized gas mains nearby, and heating with electricity is not economically feasible.
Heating a private home with wood is also popular among summer residents who stay on their property for a short time. Also wood-burning the boiler is widespread in Russian baths, where it performs two roles at once: heating and water heating.
Advantages and disadvantages
The advantages of wood-burning units include:
- No dependence on electricity. The homeowner does not have to worry about power surges or complete power outages.
- Heat generation is completely environmentally friendly. Since wood is a clean environmental product, the combustion of which does not produce any waste harmful to humans. Of course, if you don't take into account carbon dioxide, poisoning from which is possible if safety precautions are not followed.
- Available raw materials. People living near forested areas have free and accessible raw materials for heating a private home. Moreover, such a boiler can be heated using solid household waste of organic origin.
- Low cost of the unit and fittings.
- Easy installation and subsequent operation of the device.
Disadvantages include:
- Not allowed on long time leave the house unattended, as the equipment requires the constant presence and attention of a person.
- The equipment is heavy because cast iron is used to make it. This minus can be turned into a plus, since this material is durable.
- Significant fuel consumption, since wood is a material that produces little energy.
- There is no automatic mode for maintaining the required temperature.
- Low efficiency - no more than 80 percent.
- Wood heating boilers are characterized by large dimensions, so to obtain desired temperature The coolant must be burned at one time a large number of firewood
Installation Requirements
For effective and safe work wood boiler correct installation required.
1. Installation location
Any wood-burning equipment is characterized by the consumption of a fairly large amount of air, so low-power boilers are installed in common areas at home where it is performed supply and exhaust ventilation. If the boiler power is at least 50 kW, then it is necessary to equip a separate boiler room, where the useful volume of the room will be more than 8 cubic meters. The units are installed on a solid, level and fireproof base - tiles, concrete, porcelain stoneware. The walls of the boiler room must also have non-flammable material. The boiler room is equipped with forced ventilation.
2. Requirements for the chimney
Stainless steel, ceramics or thick-walled materials are used to make the chimney metal pipes. Optimal choice– a sandwich-type stainless steel chimney can be easily assembled from various elements, such as pipes held together with clamps, roof passages, and unloading platforms. When bending, bends are used at the required angle. It is possible to exhaust the chimney not only through the roof, but also through the wall of the house. To create good draft, the height of the straight section of the chimney must be more than 6 meters, and the boiler power must be 16 kW.
Choosing a wood boiler
First of all, you need to calculate required power equipment, which is indicated in the passport for the unit and is measured in kilowatts. One kilowatt of power is needed for heating 10 square meters. For example, to heat a home with an area of 100 square meters, you should choose a wood-burning boiler with a power of 10 kW. Poorly insulated rooms require a power reserve of 20–30 percent.
When choosing equipment, you should look not only at the rated power, but also at the entire operating range of the boiler - in autumn and spring it is not advisable to use the unit at full power. If the boiler will also be used to produce hot water, then it is necessary to purchase an external boiler, and also choose a boiler with an additional power reserve.
The choice of boiler is influenced by its material. As a rule, they are made from steel or cast iron. Equipment made of steel is lightweight and has a simpler firebox compared to cast iron units. Cleaning such a firebox involves removing ash from the ash pan. The chimney of steel boilers is longer, as a result of which the coolant is heated more efficiently. Cast iron units have a shorter chimney; a larger heat exchange area is formed due to the ribbed surface on which combustion particles settle, therefore To clean these devices you need to use brushes, scrapers and pokers. However, the heat capacity of cast iron models is higher.
The use of modern technologies makes it possible to divide all wood-burning boilers into the following types:
- Pyrolysis - not only firewood is used to produce heat, but also the gas released.
- Pellet - compressed granules are used as fuel, the initial raw materials for them are shavings, sawdust, bark, etc. Agricultural waste can also be used for the production of pellets.
- Water heating unit
Popular models and their costs
Model Logano G 211–26 D can be loaded various types solid fuel - coal, coke, firewood, pellets. Such a model with a power of 32 kilowatts can be purchased for 70 thousand rubles, with a power of 15 kilowatts - 50 thousand rubles.
- Zota Pellet
Models in this series not only provide heating, but are also used for hot water supply. They have a protection system. Index efficiency more than 85 percent. Equipped with electric ignition and automatic maintenance of the required temperature. The power of such a unit can reach 100 kilowatts. Weight ranges from 300 to 800 kilograms. Cost – 130–300 thousand rubles.
- Equipment of domestic production KBp
Power – 15–40 kilowatts. For heating, firewood, briquettes, and sawdust can be used, the humidity of which does not exceed 30 percent. This great option for a private home. Operation is ensured for 12 hours. Price range: 50–65 thousand rubles.
- "Geyser"
One bookmark is enough for 7–18 hours. Equipped with automatic traction control. Cost – 45–190 thousand rubles.
Since in many remote areas of the Russian Federation there is no gas supply, a wood-burning boiler for heating a private house with batteries is still a relevant solution to the heating issue. Modern models wood-burning equipment have an increased operating time from one load, differ high efficiency and safety.
Operating principles of wood-burning boilers for private homes
Modern wood-burning boilers for heating a private house with a water circuit have little in common with traditional classic stoves. By design, most models resemble an autonomous thermal station. But the basic principle of operation remains unchanged. The heat obtained by burning solid fuels is used to heat rooms.The significant difference and change made in internal structure, is the presence of a water circuit. After modifying the design, it became possible to connect a radiator heating system in a country house with a wood-burning boiler.
At the moment, according to the principle of operation, two main classes of equipment can be distinguished: 
A solid fuel boiler is simply a modified wood stove, with better automation of the combustion process and high efficiency.
How to choose a wood-burning boiler for a private home
When choosing a heating boiler for a private home, take into account several points regarding design features and performance:- Heated area - approximate calculations of productivity are carried out using the formula 1 kW = 10 m². When connecting a second circuit for DHW, another 15-20% is added to the result obtained.
- Types of heating boilers - as already noted, there are classic units, as well as those that use the principle of pyrolysis combustion. The latter are considered the most economical wood-burning boilers individual heating private country estates. The first ones cost 3-4 times cheaper.
- Type of heat exchanger - there are two types. It differs in the type of materials used and design. Boilers made of steel are cheaper, but last on average 10-15 years less. The units are not afraid of shocks and mechanical damage, and are easy to repair and maintain.
Cast iron boilers, on average, last about 35 years and have the best thermal characteristics. They are afraid of mechanical damage. Repair will require replacing the entire section. Another disadvantage of cast iron is the large weight of the boiler. A pyrolysis unit, which has two combustion chambers, easily reaches a mass of 5 centners. - Design Features combustion chamber– Manufacturers produce boilers with side loading of firewood. The design is used in most units, both classical and pyrolysis types.
Top-loading boilers deserve special attention. This design is used in gas generating units. The main advantage of the solution is the possibility of pre-drying the firewood, which increases the heating efficiency. - The presence of additional functions - automation, the presence of a backup power source, a built-in storage boiler, a remote control system - all this increases the comfort of operation and is provided as an additional package.
Which boiler to choose?
If funds allow, it is better to install a wood-burning boiler of German or Czech production. Polish and domestic units are somewhat worse in terms of production characteristics. Among foreign and domestic companies manufacturers, the leaders are:- German wood-burning boilers - represented by the companies, Lopper. All equipment has a high degree of safety and reliability, and a long service life. The disadvantage of the models is the whimsical quality and type of firewood, and the high cost.
- Wood-burning boilers are made in the Czech Republic - the products of the companies , and ATMOS deserve attention. In terms of quality and automation, the models are in no way inferior to their German counterparts, but cost on average 10% less.
- Boilers Russian production– TT units are produced by almost every heating equipment manufacturer. The boilers are adapted to domestic conditions and are unpretentious in terms of fuel quality and coolant used.
The most popular products are from the following factories: Teplodar. - Polish wood-burning boilers - several dozen modifications are offered on the domestic market. The following models are in demand: Defro, SAS, DREWMET, ORLAN. The range includes both conventional wood heat generators and pyrolysis combustion boilers.
Cost of wood boilers for country houses
The cost of the unit is influenced by several factors:- Type of heat exchanger - a cast iron boiler will cost 1.5-2 times more than a steel counterpart.
- Manufacturer.
- The principle of operation is that the cost of a wood-burning gas generator boiler from a domestic manufacturer will cost 35-40 thousand rubles, and the price of a boiler of a classical design will drop to approximately 20 thousand rubles.
- Additional equipment.
Heating installation in a private house with a wood-burning boiler
Wood-burning boilers with a water circuit for heating a private house, connected to an already existing system heating with forced or natural circulation coolant. During the installation work, comply with the requirements of PPB and SNiP.Another important issue taken into account during connection is the need to accommodate large fuel storage. The boiler burns 10-15 cubic meters of wood per season. The storage must be dry, accessible, spacious and safe.
Where can a wood boiler be installed?
A wood-fired hot water boiler for heating a private home can be installed anywhere, provided that it meets the technical and fire safety requirements. General recommendations, regarding the choice of premises for the boiler room, are:
The main requirement for operating a wood-burning boiler is compliance with safety regulations. Modern models are equipped with a multi-level security system that prevents smoke in the room and boiling of the coolant.
Heating schemes for a private house with a wood-burning boiler
Heating installation in a private house using a wood boiler is being carried out different ways. The choice of wiring diagram largely depends on the design of the boiler and the parameters of the room. All options can be divided into several classes, according to the following features:
voltage and uninterruptible power supply.
Modern wood-burning boilers are economical, safe and easy to control, and are successfully used as an alternative to gas equipment.
A long-burning wood-burning boiler can be built using two different principles. There is equipment in which fire spreads from top to bottom. Due to the gradual burnout of one layer after another, the total time from one bookmark to another increases significantly. The second technology is pyrolysis decomposition. Here, the gases that were released during the burning of wood are not sent into the chimney, but are set on fire again. This technology allows you to extract maximum heat.
Top combustion principle
The main difference from classic units is that wood burns not from below, but from above. The air supply is also carried out from above, and directly into the combustion zone, and not through the grate from below. Such boilers are mostly energy independent. And this is their big advantage. But the work is cyclical: until the entire bookmark burns out, you cannot add a new one: the temperature drops, the whole process is disrupted. This is not always convenient. There are other disadvantages as well.
Advantages and disadvantages
The advantages include the ability to regulate combustion intensity by increasing/decreasing the air flow into the firebox. If the control is manual, the boilers are non-volatile. It makes sense to install them in a system where there is no circulation pump(). But a decrease in combustion intensity greatly affects the efficiency of the boiler (it decreases).
Despite its name, such a boiler does not work for too long when burning wood: 6-8 hours. Although there are manufacturers who claim that a boiler will burn for up to 30 hours on one stack of firewood. In particular, this is what Lithuanian boiler manufacturers Stoptuva say. In its pure form, such a result is very difficult to achieve, in any case, in the reviews we saw only 14-24 hours, and not 30.
The disadvantages of top-burning boilers include their demands on fuel quality: if you load raw firewood, the efficiency of the boiler is significantly reduced.
A humidity of 13-20% is considered optimal; firewood containing 30% moisture is acceptable. If you use even more damp heat, there will be little heat. In some situations it may completely fade out. Also, when burning raw wood, a large amount of ash and soot is formed. Therefore, you have to clean the stove and chimney often.
The homemade boiler “Bubafonya” uses exactly this method. The design is very simple and accessible. It can easily be made from a gas cylinder, steel pipe or tank. T.
Pyrolysis and gas generator boilers
The operation of this type of wood-burning boiler is based on the phenomenon of pyrolysis: if wood burns with a lack of oxygen, it releases a large amount of gases. Almost all of them are flammable. Moreover, when they burn, they release much more heat than when burning wood. As a result of the pyrolysis process, it is also formed, which is superior in calorific value firewood 2.5 times.
Wood-burning gas generator boilers are called so precisely because at high combustion temperatures and a lack of oxygen, a lot of gases are formed. They seem to be generated. To release the maximum amount of heat, the combustion temperature of the wood must be above 700 o C. In some models it reaches 1200 o C.
To fully utilize all the energy that these gases can produce, they are further heated. Then it is mixed again with air and re-ignited. This process occurs in the second combustion chamber, which is also called the afterburner.
Varieties
Depending on where each chamber is located, pyrolysis boilers come with an upper or lower afterburning chamber. The most common are boilers with a lower location of the second firebox. With this design it is convenient to lay firewood. In this case, the burnt gases are discharged into a hole located below. In this way, the coldest part of the air is removed from the firebox (it is known that cold air is at the bottom).
Everything seems to be logical. But you will need to clean the stove much more often: ash from the upper chamber falls down and clogs the “pyrolysis” chamber. In addition, it will be necessary to create additional draft in the lower part, since the smoke itself will not move down.
Less common are designs with a top-mounted camera. Here the draft is simpler: the smoke tends upward on its own and no additional draft is needed.
However, such a boiler has some peculiarities: it is necessary to extract as much energy as possible from the heated air. To do this, a labyrinth is arranged at the top of the firebox. Passing through it, hot air transfers heat to the metal from which the labyrinth is made. It already heats the air (with the air heating method), or the coolant (when using water heating). This design leads to an increase in price: a lot of metal is required to make a labyrinth, and its quality must be high to ensure long-term operation at high temperatures Oh.
Advantages and disadvantages
Gas generator (pyrolysis) boilers have both advantages and disadvantages. The advantages include the fact that the fuel burns in them absolutely, almost without a residue. The peculiarities of the process allow it to be almost completely automated: all human participation in automatic boilers comes down to adding fuel and periodically cleaning it.
Automation makes it possible to regulate the intensity of work and fuel consumption. You can adjust the work to the outside temperature. There are special ones for this external sensors. You can adjust the temperature of the coolant (for water heating).
The negative point is that the system is energy dependent: no electricity - no heat. To solve this problem and further protect the automation from voltage surges, you can install complete with rechargeable batteries it will give several hours of operation after a power failure.
A fairly significant advantage is that not only firewood can be used for the gas generation process. Suitable waste from sewing, furrier and textile industries. But how “omnivorous” the boiler is needs to be clarified with the manufacturers. Usually all boilers made in Russia or Ukraine are burned out. Some imported models that are optimized for our realities may please us, but such models are rare. But you can use any and without restrictions (except for pellets, which simply fail in non-specialized equipment).
The disadvantages include high requirements for the quality of firewood, because if the moisture content of the available fuel exceeds 20%, the boiler has every chance of going out. When adding wet fuel, there is a high probability that the output will normal temperatures will be difficult and long lasting. During this time the room will cool down.
Almost all models of gas generator boilers use forced draft during operation, for which an air pump is provided in their design. This means that a guaranteed power supply must be provided. Power supply is also required for automation.
If your heating main is long enough and the coolant has time to cool before returning back to the boiler, you will have to use a bypass to mix hot water into the return pipe. If this is not done, the primary chamber may go out due to the low temperature of the coolant. And, of course, one of the main disadvantages is the considerable price of pyrolysis boilers.
Classification by heating method
Like any boilers, rooms can be heated in two ways: by directly heating the air and by heating the coolant.
Direct air heating boilers rarely used in residential areas. Only as backup or emergency heating. The advantages of such equipment are the absolute absence of additional communications, complete independence from gas, electricity and other external factors.
Installation is very simple: only a non-combustible base is required and (if there are such in the immediate vicinity - less than 1.2 m from the stove). A chimney is also needed to remove combustion products from the room. That's the whole installation.
Since such stoves have a simple design, their demands on fuel quality are lower. Anything can be used as fuel except firewood:
- peat briquettes;
- seed husk;
- coal;
- household waste;
- wood waste, chips, sawdust;
- paper, cardboard;
The Bullerjan stove-heater has proven itself well for heating air. The Bullerjan stove is a solid metal “barrel” surrounded by hollow pipes. The pipes are tightly pressed (welded) to the body. They heat up instantly, with almost no heat loss. The lower ends “suck in” cold air, and through the upper ends it comes out as warm air. This design promotes rapid heating of the room: it begins immediately after kindling.
They quickly heat the air in the room. Work on the principle of convection
“Buleryan” is designed with two combustion chambers and operates on the “clean combustion” principle. The outlet temperature of synthesis gases is 250–300 o C, and the efficiency reaches 80–85%. At the same time, the temperature of the oven itself remains quite low, and the hermetically closed door ensures compliance with all sanitary control standards.
Second type - wood-burning boilers with a water circuit. They have a heat exchanger inside, the dimensions and performance of which are calculated depending on the power of the equipment. This equipment has a completely different design. Their main task is to quickly heat the coolant, with the help of which heat will spread throughout the room. Most often, the heat exchanger is located around the entire perimeter of the firebox, taking the maximum amount of heat from its walls. Such boilers are also called hot water boilers.
Most modern wood-burning boilers have just this method of organizing heating. When purchasing wood-burning hot water boilers, you need to pay attention to such a characteristic as the maximum volume of coolant in the system. You need to take a unit with a small performance reserve: constant operation at the maximum capacity reduces the operating life, and in case of expansion of the area it is better to have at least some reserve.
Use for hot water supply
To heat water for domestic needs, a small coil heat exchanger is installed in the firebox. Cold water, supplied to its input, is heated when passing through a tube heated in the firebox. Such wood-burning boilers are also called double-circuit: the first circuit is used for water heating, the second for hot water supply.
Here you need to pay attention to this: a wood-burning stove is unlikely to be heated all year round. In summer hot water also needed. So, you will either have to install additional devices for heating water, or heat the stove in the summer.
There is another option - the so-called boiler room. With this heating method, there is a reservoir of water in the boiler, which is heated by convection. In this case, having lit the stove and heated the water, you have some supply.
Review and owner reviews
Ogonyok boilers
Worthy representatives of this type of heating equipment are wood-burning boilers “Ogonyok”. They are manufactured by the machine-building plant in Starobelsk, Lugansk region.
"Ogonyok" has a fairly diverse the lineup: With hob, with a hot water circuit, turbocharging. There are modifications equipped with a heated towel rail; boilers can be equipped with various types of automation, decorated doors, etc. The variety of models, strict compliance with GOST requirements, a wide power range - from 10 to 100 kW - allow us to characterize them as best boilers on wood made in Ukraine.
Wood-burning boiler "Ogonyok" with stove
The PDGB model operates on the principle of gas generation. Any solid fuel except coal is used as fuel. The convection type of heating is used: it directly heats the air in the room.
In the Ogonyok KOTV line, the fuel loading compartment is made wide: it can accommodate firewood up to 50 cm in length. The combustion intensity is adjusted using the chimney damper, which has 4 positions.
Ogonyok KOTV-30DT is equipped with a turbocharger to achieve higher temperatures and more efficient combustion. In this modification, loading firewood is required every 12-15 hours.
Aton boilers
Another Ukrainian-made wood burning boiler. This is the brainchild of the ATON Group corporation. The equipment is made of cast iron and steel. Cast iron wood-burning boilers "ATON TTK" are water heating units that can operate in systems with natural or. Firewood, briquettes, and peat can be used as fuel. If low quality fuel predominates, the ATON TTK V modification is better suited, which has a special fan that supplies air forcibly.
The ATON TRADICJA line is a solid fuel boiler made of steel. They have two modifications - one with a manual draft regulator, the other with automatic control. A special feature of this equipment is water-cooled grate bars. This original solution allows you to avoid one of the main problems of long-burning boilers - burnout of the grate due to high temperatures in the firebox. The ATON TRADICJA C modification with automatic control is additionally equipped with a controlled forced-air fan. This allows for long-term burning of firewood - refilling is required once every 12 hours.
Lithuanian "Kalvis"
Lithuanian Kalvis boilers have a very good feedback. This sets them apart from most other manufacturers: the stated characteristics can be trusted. The company produces both boilers-fireplaces and units with hob, hot air and water heating devices. There are household and industrial models.
Kalvis has two different options boiler devices. Low-power KALVIS-2-8 and KALVIS-2-12 are simpler. The principle of bottom combustion is used. KALVIS-2-16 and higher have a different firebox.
Perhaps the term “bottom combustion” is a consequence of a not entirely correct translation, since there are still two fireboxes, there is a primary and a secondary air supply, and the burning of wood lasts up to 12-16 hours.
For greater efficiency in heating the coolant, the combustion chambers are insulated with heat-resistant material. This also increases the combustion temperature in the firebox. The boilers have a mechanism for shaking off ash from the grate; in some models (2-12 and higher) it is possible to add fuel both from above and from the front. You can also install a smoke exhauster and an emergency cooling coil (when using coal as the main fuel).
Results
Whatever model you choose, you should still remember that even what you think are the best wood-burning boilers must be installed by specialists. They must meet not only your needs, but also the requirements fire safety, have a conclusion from the sanitary-epidemiological service on compliance with GOST. Fire safety standards must be strictly observed. Then you can be sure that your wood-burning boiler (German, Lithuanian, Ukrainian or any other production) will be safe.
