What can be cooked from squid: quick and tasty
In this article we will introduce the reader to the world of modern solid fuel heating systems. What are solid fuel water boilers?
Is the use of this particular type of fuel economically justified? Does it have serious flaws? We will try to answer all these questions.
The canonical scheme of the device, including hob... As we will see later, this is far from the best design.
Boiler classification
It is clear that all solid fuel boilers for hot water heating are characterized by a number of common features. By definition, they use the heat of combustion of wood (as an option - the products of its processing), peat or coal. In addition, the temperature of the coolant leaving the boiler does not exceed 100 degrees.
How do these devices differ from each other?
Material
We are talking about the material of both the boiler itself and its heat exchanger - the unit through which the coolant contacts the firebox.
There are two main options:
- Steel boilers are, on average, somewhat cheaper and have much less weight. However, they are also characterized by a shorter service life. Steel is a metal that is afraid of corrosion; flames and highly aggressive condensation rapidly destroy it.
However: Russian-made high-quality solid fuel heating boilers, like imported ones, are made of heat-resistant grades of corrosion-resistant steels. In addition, the firebox is often additionally protected by a refractory brick lining.
- Cast iron is a material that is much less afraid of corrosion. That is why it is used for the manufacture of grates and doors in ovens; that is why cast iron boilers, on average, are much more durable than steel ones.
The price of a longer service life is a large mass of products. As a rule, even boilers of modest (up to 16 kW) thermal power require mandatory installation exclusively on a capital foundation.
Fuel
The most versatile are solid water boilers capable of operating on several types of fuel. Without any adaptation, you can, after cleaning the ash pan, throw coal after firewood or peat briquettes after pellets into the furnace.
However, devices oriented to only one type of fuel, as a rule, have a higher efficiency. Their design is optimized for combustion with a well-defined flame temperature and fuel humidity.
In addition to single-furnace boilers, boilers with two separate fireboxes and two heat exchangers are produced. They allow you to burn different types of fuel, which require a different design of the combustion zone. In fact, a burner for a solarium will quickly deteriorate if it is among the burning wood.
Efficiency
Efficiency at different types boilers are very different. The factors determining this parameter are the temperature of the combustion products at the outlet and the amount of solid waste. In both cases, less is better.
The minimum efficiency, often not even reaching 50%, is for the simplest hand-made devices. Yes, a box made of steel sheet with two doors and a coil inside will cost quite inexpensively; however, you will have to burn a LOT of wood to get the heat you need.
Factory production of solid fuel boilers relies on accurate calculation of their shape and size of the heat exchanger. Even in younger models, the temperature of the combustion products usually does not exceed 120 degrees. In addition to the fact that more heat is given to the coolant, this also means greater fire safety.
The so-called pyrolysis, or gas-generating boilers stand apart. How do they work?
- The device contains two furnaces with heat exchangers in each of them. They communicate with each other and are placed one above the other.
- In the upper furnace, in conditions of a lack of oxygen and high temperatures, the wood smolders slowly, gradually decaying into ash. There are no large coals left during normal operation of the boiler.
However, due to the lack of an oxidizing agent, the fuel does not burn completely: it emits a large amount of pyrolysis gas, consisting of CO (carbon monoxide) and volatile hydrocarbons.
- This gas is forcibly fed into the lower furnace, where it burns out completely after oxygen-rich air is added to it.
Solid fuel gas-fired hot water boilers have a very high efficiency, reaching best devices 95 percent. However, they are 1.5-2 times more expensive than traditional designs and require low-moisture fuels. In addition, the younger models work ONLY on wood.
Autonomy
Devices of traditional design require the constant presence of a person - the furnace must be loaded every 2-4 hours. The profession of a fireman was not born on empty space... This property is the main disadvantage of solid fuels; This is partly why if main gas is available, a rare owner of a cottage will think about wood or coal.
The pyrolysis boiler, however, by virtue of the principle of its operation, makes the fuel not burn, but smolder. The boiler can operate on one load for up to 12 hours.
Relatively recently, the Lithuanian company Stropuva has established an in-line production of the so-called overhead combustion boilers. They provide heating with even greater autonomy: for certification in 2003, the serial model, after loading 50 kilograms of fuel, gave about 6 kW of thermal power for about one and a half days.
How is such a long run time achieved?
- The volume of the furnace has been increased and can hold several tens or even hundreds of kilograms of fuel.
- The grate and ash pan are absent.
- Only the top layer of the loaded fuel burns. Air to maintain combustion (more precisely, smoldering) is supplied from above through a movable unit, which, under its own weight, descends as wood or coal burns out.
- Ashes are carried away with smoke.
- The area of smoldering fuel is separated from the upper part of the chamber by a massive metal disk (slang name - stascoblin). Above it, air from the outside is added to the products of incomplete combustion of fuel, and they burn with the release of residual heat.
As you can see, at their core, these devices are pyrolysis hot water solid fuel boilers, but with serious structural modifications. It is clear that even here the price tag will not please the economical owner.
Boilers operating on pellets - pressed pellets made from sawdust - stand apart. In them, the problem of autonomy is solved by the controlled feeding of granules from the hopper.
In the photo - a boiler with a pellet hopper.
However: in addition to being expensive, these devices have another problem. Pellet production in our country is not established; not everywhere you can provide yourself with this type of fuel.
Automation
In classic boilers, all automation is limited to the simplest protection against overheating of the coolant. The mechanical thermostat with a lever pulls on the chain covering the damper. The air intake rate decreases; the heat dissipation of the boiler is reduced.
There are much more possibilities in pyrolysis heaters:
- Dampers with mechanical or electrical control here, too, allow you to adjust the draft;
- Along with this, in devices with forced draft, their thermal power can be controlled by adjusting the speed of the exhaust fan.
In addition, it is possible to control not the temperature of the coolant, but the temperature of the air in the room.
Useful: Inexpensive Russian-made solid fuel boilers are usually operated by primitive mechanical thermostat or generally only manually. You should not look for devices among the younger models that can independently maintain a comfortable temperature. However, it is precisely because of their simplicity of design that they are extremely fault-tolerant.
Advantages and disadvantages
Operating costs
At current Russian prices, purchased firewood is the second cheapest after main gas. The difference between them is small - a few percent. It is clear that it comes on the cost of generating one kilowatt-hour of thermal energy.
Coal is more expensive, but not much.
Several other factors speak in favor of firewood:
- Main gas is not available everywhere, and heating with liquefied gas costs several times more and is close to electric heating in terms of costs.
- Firewood can be harvested independently, which will reduce costs to zero.
- Solid fuel heating will make it possible to usefully dispose of most of the household waste. The rest is in the conditions country house will go into compost and fertilize the soil.
The convenience of use
But in this area there are some disadvantages.
- Combustion products must be removed. Moreover, a coaxial outlet - an air intake, as in gas boilers with a closed burner, the utilization of furnace gases will not work. We need a full-fledged chimney.
This roof decoration is an invariable attribute of solid fuel heating.
- Solid fuel boilers exist only in floor-standing design. They are massive and large in size. In most cases, it is better for them to take separate room.
- The fuel should be stored close to the boiler, and under a canopy. Compare this requirement with the convenience of being connected to gas or electricity.
- Fuel filling and removal of combustion products are often required. Even in boilers long burning, where there is no ash pan, in principle, you still have to clean the pan between the fuel tabs. Aside from the rather dirty work, this also means one more thing: you can't go away for a few days and leave the house warm.
Installation
All devices of the type we are discussing can be mounted independently. No accounting and control of utilities is required.
However, a couple of rules must be followed.
- Massive boilers are mounted, as already mentioned, exclusively on their own foundation. Putting 300 - 500 kilograms of cast iron on a wooden floor is definitely not worth it.
In general, it is better to play it safe with lighter steel ones: for example, solid fuel boilers of Belarusian production KSV 12.5 with a modest power of 12.5 kW weigh 180 kg.
- The second instruction is related to fire safety. The boiler body and chimney become noticeably hot during fuel combustion. It is recommended to place the boiler at a distance of at least half a meter from the nearest wall.
If the walls are made of combustible material, they are protected by brick or galvanized sheet with asbestos lining.
The chimney is separated from the combustible structures of the ceiling or walls with a distance of at least 25 centimeters.
Conclusion
A lot of interesting things about what solid fuel boilers are - Russian-made and imported from abroad - will tell the video at the end of the article. We hope that you will find there answers to those questions that might have remained with you.
"The boiler is really a stove in a barrel of water" ... and the efficiency of such a unit will be at best 10%, or even 3-5%. Certainly no, and a solid fuel boiler is not a stove at all, and a solid fuel stove is not a hot water boiler. The fact is that the process of combustion of solid fuel, unlike gas or flammable liquids, will certainly be extended in space and time. Gas or oil can be completely burned immediately in a small gap from the nozzle to the diffuser of the burner, but wood-coal cannot. Therefore, the requirements for the design of a solid fuel heating boiler are different than for heating furnace, it is impossible to simply put a water heater of the heating circuit in it in continuous circulation. Why this is, and how a continuous heating boiler should be arranged, and this article is intended to clarify.
Your own heating boiler in a private house or apartment becomes a necessity. Gas and liquid fuels are steadily becoming more expensive, and instead, inexpensive alternative fuels appear on the market, for example. from crop waste - straw, husks, husks. This is only from the point of view of the owners of the house, not to mention the fact that the transition to individual heating will allow getting rid of energy losses in the highways of the CHP and power lines, and they are by no means small, up to 30%
You cannot make a gas boiler yourself, if only because no one will give permission to operate it. It is forbidden to use individual boilers on liquid fuel for heating living quarters due to their high fire and explosion hazard in case of decentralized use. But a solid fuel boiler can be made with your own hands and formalized, just like a heating stove. This is perhaps the only thing that they have in principle in common.
Features of solid fuel
Solid fuel does not burn very quickly, and not all components that carry thermal energy burn in its visible flame. For complete afterburning of flue gases, a high, but quite definite temperature is required, otherwise conditions will arise for endothermic reactions (for example, nitrogen oxidation), the products of which will carry the fuel energy into the chimney.
Why isn't the boiler stove?
The furnace is a cyclic device. So much fuel is loaded into its furnace at once so that its energy is enough until the next heating. The excess combustion energy of the fuel load is partially used to maintain the optimum temperature for afterburning in the gas path of the furnace (its convective system), and is partially absorbed by the furnace body. As the load burns out, the ratio of these parts of the fuel energy changes, and a powerful heat flow circulates inside the furnace, several times more powerful than the current needs for it for heating.
The body of the furnace is, therefore, a heat accumulator: the main heating of the room occurs due to its cooling after heating. Therefore, it is impossible to take away the heat circulating in the furnace, this will in one way or another disrupt its internal heat balance, and the efficiency will drop sharply. It is possible, and even then not in every place of the convection system, to take up to 5% to feed the hot water storage tank. Also, the furnace does not need an operative adjustment of its thermal power, it is enough to load fuel based on the required hourly average for the time between heating.
A water boiler, no matter what fuel, is a continuous-action device. The coolant circulates in the system all the time, otherwise it will not heat up, and the boiler must at any given moment give exactly as much heat as it has gone outside due to heat loss. That is, the fuel must either be periodically loaded into the boiler, or the thermal power must be quickly regulated within a fairly wide range.
The second point is flue gases. They must come up to the heat exchanger, firstly, as hot as possible in order to ensure high efficiency. Secondly, they must be completely burnt out, otherwise the fuel energy will settle on the register with soot, which will also need to be cleaned.
Finally, if the stove heats up around itself, then the boiler as a heat source and its consumers are spaced apart. The boiler requires a separate room (boiler room or furnace): due to the high concentration of heat in the boiler, its fire hazard much higher than the ovens.
Note: an individual boiler room of a residential building must have a volume of at least 8 cubic meters. m, ceiling not less than 2.2 m high, opening window not less than 0.7 sq. m, a constant (without dampers) inflow of fresh air, a smoke channel separate from other communications and a fire interchange from the rest of the rooms.
From this it follows, firstly, boiler furnace requirements:
- It must ensure fast and complete combustion of fuel without a complex convection system. This can only be achieved in a firebox made of materials with the lowest possible thermal conductivity, because a high concentration of heat is required for fast afterburning of gases.
- The firebox itself and the parts of the structure associated with it in terms of heat should have the lowest possible heat capacity: all the heat that went into heating them will remain in the boiler room.
These requirements are initially contradictory: materials that do not conduct heat well, as a rule, accumulate it well. Therefore, an ordinary stove furnace for a boiler will not work, you need some kind of special one.
Heat exchange register
The heat exchanger is the most important unit of the heating boiler, it basically determines its efficiency. By the design of the heat exchanger, the entire boiler is called. In household heating boilers, heat exchangers are used - water jackets and tubular, horizontal or vertical.
A boiler with a water jacket is the same "stove in a barrel", a heat exchange register in the form of a tank surrounds the firebox in it. A jacketed boiler can be quite economical on one condition: if the combustion in the furnace is flameless. A fiery solid fuel furnace certainly requires the afterburning of the exhaust gases, and in contact with the jacket, their temperature immediately drops below the value required for this. The result is an efficiency of up to 15% and enhanced deposition of soot, and even acid condensate.
Horizontal registers, generally speaking, are always inclined: their hot end (supply) must be raised above the cold (return), otherwise the coolant will reverse, and the failure of forced circulation will immediately lead to a serious accident. In vertical registers, the pipes are located vertically or with a slight inclination to the side. Both there and there the pipes are arranged in rows in a checkerboard pattern so that the gases are better “entangled” in them.
With regard to the directions of movement of hot gases and coolant, pipe registers are divided into:
- Flowing - gases pass generally perpendicular to the coolant current. Most often, such a scheme is used in horizontal industrial boilers of high power for the sake of their lower height, which makes the installation cheaper. In everyday life, the situation turns out to be the opposite: in order for the register to properly catch the heat, it has to be made stretched up above the ceiling.
- Counterflow - gases and coolant move along one line towards each other. This arrangement provides the most efficient heat transfer and the highest efficiency.
- Stream - gases and coolant move in parallel in the same direction. It is rarely used in boilers for special purposes, because At the same time, the efficiency is poor, and the wear of the equipment is high.
Further, heat exchangers are made of fire tube and water tube. In a fire tube, the flue gas tubes pass through the water tank. Fire-tube registers work stably, and vertical ones give good efficiency even in a flow-through scheme, because an internal water circulation is installed in the tank.
However, if we calculate the temperature gradient optimal for transferring heat from gas to water based on the ratio of their density and heat capacity, then it turns out to be about 250 degrees. And in order to push this heat flux through the wall of a steel pipe of 4 mm (it cannot be less, it will burn out very quickly) without noticeable losses on the thermal conductivity of the metal, about 200 degrees are needed. As a result, the inner surface of the fire tube should be heated up to 500-600 degrees; 50-150 degrees - operational reserve for fuel water cut, etc.
Because of this, the service life of the flue tubes is limited, especially in large boilers. In addition, the efficiency of a fire-tube boiler is low, it is determined by the ratio of the temperatures entering the register of hot gases and leaving the chimney. It is impossible to let the gases cool below 450-500 degrees in a fire-tube boiler, and the temperature in an ordinary furnace does not exceed 1100-1200 degrees. According to the Carnot formula, it turns out that the efficiency above 63% cannot be obtained, and even the efficiency of the furnace is not more than 80%, so that in total it turns out 50%, which is really bad.
In small household boilers, these features are less pronounced, because with a decrease in the size of the boiler, the ratio of the register surface to the volume of flue gases in it increases, this is the so-called. square-cube law. In modern pyrolysis boilers, the temperature in the combustion chamber reaches 1600 degrees, the efficiency of their furnace is at 100%, and the registers of branded boilers are made only thin-walled from heat-resistant special steel for 5 years or more. In them, gases can be allowed to cool down to 180-250 degrees, and overall efficiency reaches 85-86%
Note: cast iron is generally unsuitable for smoke tubes, it cracks.
In water-tube registers, the coolant flows through pipes placed in a fire chamber, where hot gases are supplied. Now the temperature gradients and the square-cube law act the other way around: at 1000 degrees in the chamber, the outer surface of the pipes will be heated to only 400 degrees, and the inner one - to the temperature of the coolant. As a result, pipes made of ordinary steel serve for a long time and the boiler efficiency is about 80%
But horizontal flow-through water-tube boilers are prone to the so-called. "Booze". The water in the lower pipes turns out to be much hotter than in the upper ones. It is pushed into the supply in the first place, the pressure drops, and the colder upper pipes "spit out" the water. "Buhting" not only gives noise, warmth and comfort as much as a neighbor is a drunkard and a brawler, but is also fraught with a rush in the system due to water hammer.
Vertical water-tube boilers are not coiled, but if a water-tube boiler is being designed into a house, the register must be located at the lowering of the chimney, in that section where hot gases go from top to bottom. In a flow, with the same direction of movement of gases and a coolant, a water-tube boiler, the efficiency drops sharply and soot is intensively deposited on the pipes near the supply, and it is generally unacceptable to make a return flow above the supply.
About the capacity of the heat exchanger
The ratio of the capacities of the heat exchanger and the entire cooling system is not taken arbitrarily. The rate of heat transfer from gases to water is not infinite; the water in the register must have time to absorb heat before it leaves the system. On the other hand, the heated outer surface of the register gives off heat to the air, and it is wasted in the boiler room.
Too small register is prone to boiling and requires precise fast adjustment of the furnace power, which is unattainable in solid fuel boilers. A large-volume register takes a long time to warm up and, with poor external boiler insulation or its absence, it loses a lot of heat, and the air in the boiler room can warm up above the permissible fire safety and technical specifications for the boiler.
The value of the capacity of the heat exchanger of solid fuel boilers ranges from 5-25% of the capacity of the system. This must be taken into account when choosing a boiler. For example, for heating, according to the calculation, there were only 30 sections of radiators (batteries), 15 liters each. With water in the pipes and an expansion tank, the total capacity of the system will be about 470 liters. The capacity of the boiler register must be in the range of 23.5-117.5 liters.
Note: there is a rule - the greater the calorific value of solid fuel, the greater the relative capacity of the boiler register should be. Therefore, if the boiler is coal, the register capacity must be taken closer to the upper value, and for the wood boiler - to the lower one. For slow-burning boilers, this rule is not true, the capacity of their registers is calculated based on the highest boiler efficiency.
What to make a heat exchanger from?
Cast iron as a material for the boiler register does not meet modern requirements:
- Low thermal conductivity of cast iron leads to low boiler efficiency, because it is impossible to cool the exhaust gases below 450-500 degrees, as much heat will not pass through the cast iron into the water.
- The large heat capacity of cast iron is also its minus: the boiler must quickly give off heat to the system before it evaporates somewhere else.
- Cast iron heat exchangers do not fit into modern requirements for weight and dimensions.
For example, let's take the M-140 section from the old Soviet cast iron battery. Its surface area is 0.254 sq. m. For heating 80 sq. m. of living space you need a heat exchange surface in the boiler of about 3 sq. m, i.e. 12 sections. Have you seen a 12-cell battery? Imagine what a cauldron should be, in which it will fit. And the load from it on the floor will definitely exceed the limit according to SNiP, and a separate foundation will have to be made under the boiler. In general, 1-2 cast iron sections will go to the heat exchanger feeding storage tank DHW, but for a heating boiler the question of the cast-iron register can be considered closed.
Registers of modern factory boilers are made of heat-resistant and heat-resistant special steel, but production conditions are required for their manufacture. The usual structural steel remains, but it corrodes very quickly at 400 and higher degrees, therefore, fire tube boilers made of steel must be chosen for purchase or developed very carefully.
In addition, steel conducts heat well. On the one hand, this is not bad, you can expect to get a good efficiency by simple means. On the other hand, the return flow should not be allowed to cool below 65 degrees, otherwise acid condensate will fall out of the flue gases on the register in the boiler, which can go through the pipes within an hour. You can exclude the possibility of its precipitation in 2 ways:
- With a boiler output of up to 12 kW, a bypass valve between the boiler flow and return is sufficient.
- With a higher power and / or heated area of more than 160 sq. m need more elevator unit, and the boiler must operate in the mode of superheating water under pressure.
The bypass valve is controlled either electrically from a temperature sensor, or non-volatile: from a bimetallic plate with a thrust, from wax melting in a special container, etc. As soon as the temperature in the return flow drops below 70-75 degrees, it lets hot water out of the filing.
The elevator unit, or simply the elevator (see fig.) Acts the other way around: the water in the boiler is heated to 110-120 degrees under a pressure of up to 6 atm, which excludes boiling. For this, the combustion temperature of the fuel is increased, which increases the efficiency and excludes condensation. And before feeding into the system, hot water is diluted with a return flow.
In either case, forced circulation of water is required. Nevertheless, it is quite possible to create a steel boiler with thermosyphon circulation, which does not require power supply for the circulation pump. Some constructions will be discussed below.
Circulation and boiler
Thermosiphon (gravitational) water circulation does not allow heating a room with an area of more than 50-60 square meters. m. The point is not only that it is difficult for water to squeeze through the developed system of pipes and radiators: if the drain valve is opened with a full expansion tank, water will pour out in a strong stream. The fact is that the energy for pushing water through the pipes is taken from the fuel, and the efficiency of converting heat into motion in a thermosyphon system is scanty. Therefore, the efficiency of the boiler as a whole falls.
But the circulation pump needs electricity (50-200 W), which can be lost. UPS (uninterruptible power supply) for 12-24 hours of autonomous operation is very expensive, therefore a properly designed boiler is expected to have forced circulation, and in the event of a power outage, it should switch to thermosyphon mode without outside interference, when the heating is barely warm, but still warms up.
How is the boiler installed?
The requirement for the minimum own heat capacity of the boiler directly results in its small weight in comparison with the furnace and its weight load per unit floor area. As a rule, it does not exceed the minimum permissible according to SNiP for flooring 250 kg / sq. m. Therefore, the installation of the boiler is permissible without a foundation and even parsing the flooring, incl. and on the upper floors.
Place the boiler on a flat, stable surface. If the floor is playing, it will still have to be disassembled at the boiler installation site to a concrete screed with a sideways extension of at least 150 mm. The base for the boiler is covered with asbestos or basalt cardboard 4-6 mm thick, and a sheet of roofing iron with a thickness of 1.5-2 mm is placed on it. Further, if the flooring was disassembled, the bottom of the boiler is lined with cement-sand mortar to the floor level.
Around the boiler protruding above the floor, thermal insulation is made, the same as under the bottom: asbestos or basalt cardboard, and iron on it. Removal of insulation to the sides of the boiler from 150 mm, and in front of the firebox door not less than 300 mm. If the boiler allows additional fuel loading before the previous portion burns out, then the removal in front of the firebox is needed from 600 mm. Under the boiler, which is placed directly on the floor, only heat insulation, covered with a steel sheet, is placed. Removal - as in the previous case.
For a solid fuel boiler, a separate boiler room is required... The requirements for it are given above. In addition, almost all solid fuel boilers do not allow power adjustment over a wide range, so they need a full-fledged piping - a set of additional equipment that ensures efficient and trouble-free operation. We will talk about it further, but in general the boiler piping is a separate big topic. Here we will only mention the immutable rules:
- The piping is installed in a counterflow to the water, from the return to the supply.
- At the end of the installation, its correctness and quality of the connections are checked visually according to the scheme.
- The installation of the heating system in the house is started only after the boiler is piped.
- Before loading fuel and, if required, applying power, the entire system is filled with cold water and during the day all joints are monitored for leaks. In this case, water is water, and not some other coolant.
- If there are no leaks, or after they have been eliminated, the boiler is started on water, continuously monitoring the temperature and pressure in the system.
- After reaching the nominal temperature, the pressure is controlled for 15 minutes, it should not change by more than 0.2 bar, this process is called pressure testing.
- After pressure testing, the boiler is extinguished, the system is allowed to cool completely.
- Drain the water, fill in the standard coolant.
- Once again, the joints are monitored for a day. If everything is in order, the boiler is started. No - they eliminate leaks, and again daily control before starting.
Choosing a boiler
Now we know enough to choose a boiler based on the intended type of fuel and its purpose. Let's get started.
Wood burning
The calorific value of firewood is low, the best ones have less than 5000 kcal / kg. Firewood burns rather quickly, releasing a large volume of volatile components requiring afterburning. Therefore, it is better not to rely on high efficiency on wood, but they can be found almost everywhere.
Wood burning in the house
A home wood-burning boiler can only be burning for a long time, otherwise it beats it in all respects. Industrial structures, for example. the well-known KVR, cost from 50,000 rubles, which is still cheaper than building a furnace, do not require power supply and allow power adjustment for heating in the off-season. As a rule, they work both on coal and on any solid fuel, except for sawdust, but on coal the fuel consumption will be much higher: heat transfer from one load is 60-72 hours, and for specialized coal ones - up to 20 days.
Nevertheless, a long-burning wood-burning boiler can be useful in places where there is no regular coal delivery and qualified heating service. It costs one and a half times cheaper than coal, its jacket design is very reliable and allows you to build a thermosiphon heating system with an area of up to 100 sq. m. In combination with the smoldering of fuel, a thin layer and a rather large volume of the jacket, boiling of water is excluded, therefore, the piping is the same as for titanium. Connecting a boiler for long burning on wood is also no more difficult than titanium, and can be done independently by an unqualified owner.
About brick boilers
Diagram of the boiler "Blago"
Brick is a friend of a stove and an enemy of a boiler due to the fact that it gives a structure a large thermal inertia and weight. Perhaps the only brick boiler in which the brick is in place is Belyaev's pyrolysis "Blago", the diagram in fig. And then, its role here is completely different: the lining of the combustion chamber is made of fireclay bricks. Horizontal water-tube heat exchanger; the problem of coiling is solved by the fact that the register pipes are single, flat, elongated in height.
Belyaev's boiler is really omnivorous, and there are 2 separate bunkers for loading different types of fuel without stopping the boiler. On anthracite "Blago" can work for several days, on sawdust - up to a day.
Unfortunately, the Belyaev boiler is quite expensive, because of the fireclay lining, it is poorly transportable and, like all pyrolysis boilers, requires complex and expensive piping. Its power is regulated within small limits by the bypass of flue gases, therefore, it will show good efficiency on average per season only in places with prolonged severe frosts.
About boilers in the oven
The boiler in the furnace, which is now so much talked about and written about, is a water-tube heat exchanger walled up in stove masonry, see fig. below. The idea is this: after firing, the stove should give off heat more to the register than to the surrounding air. Let's say right away: reports of an efficiency of 80-90% are not only dubious, but simply fantastic. The best brick oven itself has an efficiency of no more than 75%, and its outer surface area will be at least 10-12 square meters. m. The surface area of the register is hardly more than 5 square meters. m. In total, less than half of the heat accumulated by the stove will go into the water, and the overall efficiency will be below 40%
The next moment is furnace with a register immediately loses its property... In no case should you drown it out of season with an empty register. The TCR (temperature coefficient of expansion) of the metal is much greater than that of a brick, and the heat exchanger swollen from overheating will break the furnace before our eyes. Heat seams will not help business, the register is not a sheet or beam, but a volumetric structure, and it is bursting in all directions at once.
There are other nuances here, but the general conclusion is unambiguous: a stove is a stove, and a boiler is a boiler. And the fruit of their violent unnatural union, the stove boiler will not be viable.
Boiler piping
Boilers that exclude boiling water (long-burning jacket, titanium) cannot be made for a power of more than 15-20 kW and are extended in height. Therefore, they always provide heating of their area in thermosyphon mode, although a circulation pump, of course, will not interfere. Their piping, in addition to the expansion tank, includes only an air drain valve at the highest point of the supply pipeline and a drain valve at the lowest point of the return.
The piping of solid fuel boilers of other types should provide a set of functions, which is better understood in Fig. on right:
- safety group: an air drain valve, a general pressure gauge and a breakthrough valve to release steam when boiling;
- emergency cooling storage tank;
- his float valve, the same as in the toilet;
- thermal valve for starting emergency cooling with its sensor;
- MAG-block - drain valve, emergency drain valve and pressure gauge, assembled in one housing and connected to a diaphragm expansion tank;
- forced circulation unit with check valve, a circulation pump and an electrically temperature controlled three-way bypass valve;
- intercooler - emergency cooling radiator.
Pos. 2-4 and 7 make up the power shedding group. As already mentioned, solid fuel boilers are regulated in power within small limits, and in case of sudden warming, the entire system may overheat unacceptably, up to a gust. Then the thermal valve 4 lets tap water into the intercooler, and it cools the supply to normal.
Note: the owner's money for fuel and water at the same time quietly and peacefully flows into the sewer. Therefore, solid fuel boilers are not suitable for places with mild winters and a protracted off-season.
The forced circulation group in the normal mode bypasses part of the supply to the return line so that its temperature does not fall below 65 degrees, see above. When the power supply is cut off, the thermal valve slams. The heating radiators receive as much water as they will pass in the thermosyphon mode, if only it would be possible to live in the rooms. But the thermal valve of the intercooler opens completely (it is kept closed under voltage), and the excess heat again carries the owner's money into the drain.
Note: if water disappears along with the electricity, the boiler must be extinguished urgently. When water flows out of tank 2, the system will boil.
Boilers with built-in protection against overheating are 10-12% more expensive than conventional ones, but this is more than pays off by simplifying the piping and increasing the reliability of the boiler: the excess of overheated water is poured here into an open expansion tank of large capacity, see fig., From where it cools down and flows into return line. The system, in addition to the circulation pump 7, is non-volatile and goes into thermosyphon mode smoothly, but in case of sudden warming, the fuel is still wasted, and the expansion tank must be installed in the attic.
As for the pyrolysis boilers, the typical scheme of their piping is provided for information only. All the same, its professional installation will cost only a small fraction of the cost of the components. For reference: a heat accumulator alone for a 20 kW boiler costs about $ 5000.
Note: membrane expansion tanks, unlike open ones, are installed on the return flow at its lowest point.
Chimneys for boilers
Chimneys of solid fuel boilers are calculated in general in the same way as furnaces. General principle: a chimney that is too narrow will not give the required draft. This is especially dangerous for the boiler, because it is heated continuously and the waste can go at night. Too wide a chimney leads to a "whistle": cold air descends through it into the firebox, chilling the stove or register.
The boiler flue must meet the following requirements: distance from the roof ridge and between different chimneys not less than 1.5 mm, the extension above the ridge is also not less than 1.5 m. Safe access to the chimney must be provided on the roof at any time of the year. At each break in the chimney outside the boiler room, there must be a clean door, each passage of the pipe through the ceilings must be thermally insulated. The upper end of the pipe must be equipped with an aerodynamic cap, which is mandatory for the boiler chimney, in contrast to the stove. Also, a condensate collector is required for the boiler chimney.
In general, the calculation of the chimney for a boiler is somewhat simpler than for a stove, because the boiler chimney is not so tortuous, the heat exchanger is considered simply for a lattice barrier. Therefore, it is possible to build generalized graphs for different design cases, for example. for a chimney with a horizontal section (hog) of 2 m and a condensate collector with a depth of 1.5 m, see fig.
Based on such graphs, it is possible, after an accurate calculation based on local data, to estimate whether there was a gross error. If the calculated point is somewhere around its generalized curve, the calculation is correct. In extreme cases, you will have to build up or cut the pipe by 0.3-0.5 m.
Note: if, say, for a pipe with a height of 12 m, there is no curve for a power less than 9 kW, this does not mean that a 9 kW boiler cannot be operated with a shorter pipe. It's just that for pipes lower than a generalized calculation is no longer possible, and you need to calculate exactly according to local data.
Video: an example of the construction of a solid fuel boiler of mine type
conclusions
The depletion of energy resources and the rise in fuel prices have radically changed the approach to the design of domestic heating boilers. Now they, like industrial ones, require high efficiency, low thermal inertia and the ability to quickly regulate power over a wide range.
In our time, heating boilers, according to the basic principles laid down in them, finally parted with stoves and were divided into groups for different climatic conditions. In particular, the considered solid fuel boilers are suitable for areas with harsh climates and prolonged severe frosts... For places with a different climate, heating devices of other types will be preferable.
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Solid fuel boilers for heating a private house can operate on coal, wood, briquettes, peat or coke. Autonomous equipment does not depend on the electricity supply or the central gas line. Combined devices are popular, which can operate from a primary and secondary source.
Correctly selected solid fuel unit allows you to heat all rooms in the house as efficiently as possible
Solid fuel boilers for heating a private house: design features
Solid fuel units are made of durable steel or cast iron. These materials affect the service life and cooling rate of the structure. Steel models are resistant to temperature extremes and pressure. Cast iron is characterized by resistance to corrosion.
A long burning cast iron solid fuel heating boiler is suitable for houses with permanent residence. Its advantages include durability, ease of maintenance and long cooling.
Steel appliances are characterized by easy loading, reasonable price and high aesthetics. The boilers are equipped with one or two circuits. Two rings allow not only heating the house, but also supplying hot water. Depending on the fuel combustion time, the equipment is divided into traditional and pyrolysis equipment.
Attention! The steel chimney must be equipped with a linear deformation compensator, which is needed to maintain the tightness of the bushing connections.
Strapping schemes
When choosing solid fuel boilers for, it is worth considering the piping scheme. Do not connect the unit directly to the heating circuit. As this contributes to the formation of condensation and deposits.
To organize the optimal operation of the equipment, you should use the following methods:
- installation of an expansion tank;
- installation of a safety group with an adjustable valve;
- installation between the unit and the heat storage tank circuit;
- installation of a hydraulic circuit separator.
There are several strapping schemes that differ in the number of circuits or their complexity. What matters is the piping layout, as well as the ways of circulating the coolant.
Important! The boiler itself is piped only with metal pipes.
Models of solid fuel heating boilers for long burning
You can buy excellent domestic solid fuel boilers for heating a private house. By comparing the advantages and disadvantages of individual models, as well as their characteristics, you can choose the best option.
The advantages of boilers of the Pellet and Zota Mix model range include:
- high efficiency rate;
- combined steel models operate on any type of fuel;
- the ash container and the combustion chamber are located inside the water jacket;
- chimney damper, air suction and mechanical traction regulator installed in the furnace door ensure complete combustion with low draft;
- the surface of the body is treated with an anti-corrosion compound;
- availability when performing repair work.
These models have certain disadvantages. You need a supply of fuel, as well as a place to store it. The structure is installed in a separate room. It is important to prepare special water for the boiler.
When choosing a solid fuel boiler with a water circuit, it is worth considering the AKTV devices, which are manufactured by Sibteploenergomash. Their advantages include:
- affordable price;
- compact size;
- ash drawer;
- the ability to connect to the heating piping;
- devices can operate on electricity and gas.
The disadvantages include primitive automation and outdated design.
It is also worth considering Bourgeois from the TPP company.
It is worth highlighting the following advantages of this equipment:
- one bookmark is required to operate the equipment for 8 hours;
- low fuel consumption;
- the generator is suitable for forced and natural circulation systems;
- environmental friendliness of the unit.
Among the minuses, it is worth noting the complexity of installation, the need for manual bookmarking and significant weight.
Useful information! To heat a greenhouse, garages or country houses, you can build structures with your own hands.
Price overview
An important parameter is the price. Solid fuel boilers for long burning, depending on the manufacturer and technical characteristics, may have different prices.
| Image | Models | Heating area, m2 | Average price, rub. |
|---|---|---|---|
 | Zota Mix 32 | 250 | 38 700 |
| Zota Mix 50 | 400 | 54 500 | |
 | Pellet 15 A | 150 | 16 200 |
| Pellet 45 A | 400 | 22 700 | |
 | Karakan 8 TPE | 80 | 11 700 |
 | Karakan 12 TEG | 120 | 21 200 |
 | FBI Co12 | 100 | 52 500 |
 | Traian T 15 A | 150 | 57 100 |
| Traian T 20 A | 250 | 61 800 | |
| Traian T 30 A | 320 | 71 400 |
The problem of heating your own home is one of the most difficult tasks, which the owner of the house has to decide. It will not be possible to ignore this question - it will be impossible to live in an unheated building for almost half a year, and sharp temperature drops will quickly age the whole interior decoration and shorten the life of the entire structure.
The optimal solution to the issue seems to be the creation of an in-house system with the circulation of the coolant through pipes and radiators installed in the premises in the required quantity. This means that the main problem is the choice of a heat generator, simply a boiler, which will convert an external source of energy into heating. And in this matter, based on the characteristics of the climate in the overwhelming part of the territory of Russia, the degree of accessibility, including price, of certain energy resources, boilers for long burning on solid fuels are gaining more and more popularity.
Today, the most convenient option is traditionally considered to be the installation gas boiler... However, far from all settlements, and even more so in suburban summer cottages, gas supply networks have been laid. In addition, the supply of an individual line from the main, if available, is a very serious cost.
If we add to this the inevitable approval procedures, drawing up a project in compliance with all the requirements of the regulatory authorities, then such a heating method can scare away the owners of the house, especially in conditions when there is a worthy alternative to it.
It would seem that a very acceptable option is the use of electricity. A lot of electric boilers are produced, they are distinguished by high efficiency, ease of adjustment, saturation of control systems and automatic control of the heating system. But all these very significant benefits are easily broken down into the main "underwater rock"- the cost of a kilowatt of electricity. The average family simply goes broke on just one thing.
In addition, it is no secret that in villages remote from large centers, drops in the power grid, alas, are not uncommon. Putting yourself in complete dependence on the stability of the power grids is probably not the best option.
Against the background of the development of modern energy technologies, the traditional for Russian open spaces method of heating their homes using ordinary firewood has gradually “faded into the shadows”. But this is a renewable energy source, and with a lack of such fuel in vast territories of the country there is simply no such thing as self-procured firewood, purchased wood, waste from woodworking enterprises, and old dead wood, which still needs regular cleaning. In short, wood was and remains the most affordable fuel in the forested areas of the country.
Of course, they never completely refused to use firewood, and the owners carefully repaired the stoves in the houses of the old building and used them for their intended purpose. But in new buildings, the installation of a stone stove or fireplace is done rather as a tribute to fashion, and not in order to completely switch to solid fuel.
But, oven oven - it keeps heat for a long time due to thick brick walls and a well-thought-out system of channels for the exit of firewood combustion products. It can be heated once a day to provide a suitable microclimate for living in the room. But what about the water heating circuits? If you just constantly keep the fire in the boiler's furnace, as in an ordinary wood-burning stove, then it will be ruinous in terms of fuel consumption, and it will be extremely tiring - every 2 — 3 hours, or even more often, add a new portion of firewood. However, a way out was found - this was embodied in the creation of a long burning.
Special design of the heater, based on the ones used during its operation physico-chemical properties of solid fuel, it allows you to load firewood no more often than once every 12 - 15 hours, and in some models this period is even longer, and sometimes even several days.
The advantages of such boilers are also that many of them can be used as fuel, in addition to firewood, and other types of it. This can be, for example, compressed briquettes from wood waste - pellets, which can be purchased in a store, and in some cases even made by yourself.
Pellets - granular fuel for long burning boilers
Coal or peat is used for solid fuel boilers. Recently have become popular the so-called "eurowood".
Wood waste processing product - briquettes or "eurowood"
It is also a waste product from the woodworking industry, which is highly energy-intensive and very easy to use.
Principles of operation of long-burning boilers
The principle of operation of a conventional solid fuel furnace is probably known to everyone. Firewood (coal, briquettes) is put into the combustion chamber, and from the lower blower chamber there is an air stream containing oxygen necessary for the combustion process. The intensity of combustion is limited only by the volume of incoming air and the area of the outer surface of the fuel insert.
In fact, this is an ordinary fire, only enclosed in stone or metal walls, and requires constant replenishment of fuel. In this case, the combustion products are almost directly discharged into the chimney system, the labyrinths and turns of which only improve the heat transfer to the structural elements and, in a certain wall, lead to an increase in efficiency, but in no way can increase the overall energy efficiency of a particular type of fuel. The process of thermal decomposition of wood is very intense, short-lived, leaving a lot of waste and throwing unused opportunities into the atmosphere.
And these possibilities lie in the special properties of wood, which are due to its biochemical composition. During the heating process, this material does not simply oxidize to the state of coal with the release of ordinary carbon dioxide (CO2) and carbon monoxide (CO). High-temperature exposure always leads to the synthesis of volatile hydrocarbon compounds with a complex chemical formula, and they themselves are an excellent gaseous fuel, which is simply emitted into the atmosphere in conventional furnaces.
The process of thermal decomposition of wood is called pyrolysis, respectively, the hot gaseous components released during this process are called pyrolysis gas. It is characteristic that the temperature of its combustion, and hence the heat transfer, is incomparably higher than that obtained with the usual burning of wood. At the same time, the processes of wood oxidation are so deep that after them there is practically no waste in the form of ash, and after the combustion of the gaseous component, mainly water vapor and carbon dioxide are emitted into the atmosphere.
This means that from the point of view of the technology of the most rational use of wood fuel, it is advisable to minimize the process of open combustion, to achieve the maximum release of pyrolysis gas, which will, in fact, be the main source of thermal energy during combustion. It is these principles that are incorporated into the design of long-burning boilers.
Varieties of solid fuel boilers for long burning
So, as it has probably already become clear from the principle of operation, the main technological challenge, which must be solved for its correct operation, is the metering of air entering the chamber for preliminary thermal decomposition of firewood and adjusting the flows of the resulting pyrolysis gases and secondary heated air for their combustion in the main combustion chamber, where, in fact, the main heat exchange with the heating circuit is organized.
With the generality of the problem, in different models it is technically solved in its own way.
1. One of the options are designs in which air is pumped using a built-in fan, and the flow is regulated by an automation unit.
Most of these boilers are designed in such a way that the chamber for loading and pre-combustion of fuel is located at the top.
After ignition of the laid firewood, the air supply to them is reduced to a minimum, and the fan provides air flow through the lower chamber of the main afterburner, which is made of heat-resistant materials (chamotte or ceramic concrete), which do not allow metal parts to quickly burn out and, in addition, become good heat accumulators. The created thrust constantly "sucks" the generated pyrolysis gas into the lower chamber. At the entrance to it, ceramic nozzles are installed that can withstand extreme temperatures - over 1000 degrees Celsius.
Combustible pyrolysis gases provide the main heat exchange with pipes or "jacket" of the water circuit. Circulating, which is usually also tied to the boiler automation unit, ensures the movement of the coolant through the pipes and radiators of the heating system.
If you look at the video presented, then even visually you can compare the very intensity of firewood burning in the loading chamber (almost at the level of slow smoldering) and the incomparable power of combustion of pyrolysis gas in the main combustion chamber.
Video: design and operation of the long-burning pyrolysis boiler "Motor Sich«
This arrangement of chambers is not at all a "dogma" for this type of long-burning boilers. So, for example, in boilers of the Gefest-profi model range, the afterburner is moved back.
It has a complex labyrinthine structure, which contributes to the most efficient heat exchange with the heating circuit. Due to this, a very high efficiency is achieved - up to 90 ÷ 93%, almost all the heat is spent on heating the coolant. This is evidenced by the fact that the temperature of the gases at the outlet to the chimney is only about 70 - 110 degrees.
The mentioned boilers with electronic regulation are good for everyone, however, they have a very significant drawback. They are completely volatile - when the power supply is turned off, the fans and the automation unit do not work, which means that the entire heating system becomes inoperative, even if there is a possibility of natural circulation of the coolant around the circuit in the house. Of course, there is a way out - this is the installation of an uninterruptible power supply system, but it is good for emergencies. If power outages are frequent, then some other option will have to be chosen.
Such boilers are also very picky about the mains voltage drops - the automation may not work correctly, and often they require the installation of a separate stabilizer.
2. Non-volatile long-burning boilers, in which regulated air circulation is organized due to natural draft, are devoid of such disadvantages. An example of such heating devices is the popular Trayan model of the Russian trade and production association of the same name and Bourgeois-K of the Kostroma plant "Teplogarant", which are popular among consumers.
The main advantage of such boilers is complete energy independence.
They have an extensive loading chamber at the bottom, and under it is located ash pan- everything is like in a classic oven. The damper on the air access door located below is mechanically (through a chain) connected to a bimetallic thermostat.
After loading the firewood and lighting it up, the damper is open to the maximum - this is necessary so that confident combustion of the fuel begins and the pyrolysis processes start, for which a temperature of at least 200 degrees is needed.
Then the damper is closed in such a way as to minimize the flow of oxygen into the wood burning zone, and the chamber switches to the smoldering mode. The air, having passed through special channels for the necessary heating to the desired temperature, enters the upper chamber. Its supply is carried out through special tubes, in which there are calibrated holes. Leaving through these peculiar burners, atmospheric oxygen enters into an oxidative reaction with pyrolysis gas rising from the combustion chamber. Its effective afterburning takes place with the release of a large amount of heat, which is spent on heating the coolant circulating through the pipes and the water "jacket" of the boiler.
Video: a diagram of the structure and operation of a long-burning boiler of the "Trayan" type
The boiler is completely non-volatile, so it can be fully used in the absence of electricity in an open or closed heating system with natural circulation of the coolant.
For the sake of fairness, it should be noted that such a scheme still evokes a lot of criticism from experts. It is difficult to argue here - indeed, according to his The efficiency and economy of firewood consumption, it is seriously inferior to boilers with electronic regulation and forced creation of air flows and pyrolysis gases. However, independence from electricity and ease of operation make such boilers very popular with Russian consumers.
3. Another technological approach to providing solid fuel with subsequent afterburning of pyrolysis gas is the creation of such conditions that the process of burning firewood goes from top to bottom, only in a relatively thin layer of loading. This principle, for example, is applied in the popular and proven boilers of the Stropuva model range of the Lithuanian company of the same name.
These boilers have the characteristic shape of a vertical cylinder. They can use almost any type of solid fuel - wood, sawdust, wood chips, coal, briquettes, etc. An impressive loading chamber allows them to work on one tab for a very long time. So, on one load of firewood, the boiler, depending on the specific model, is capable of functioning from 1 to 3 days, and on coal this period is even more impressive - from 3 to 7 days.
The secret lies in the boiler design:
- The available fuel is loaded into the combustion chamber (8) through the window (6). Then, surface ignition is carried out using conventional flammable furnace fluids. As soon as combustion has started, the air distributor (7) is lowered onto the fuel tab - it will supply oxygen only to the upper burning layer. Its design provides for special channels that contribute to the uniform distribution of the air flow over the combustion area.
- In order for the process of surface combustion with the accompanying pyrolysis to proceed as efficiently as possible, the air needs preliminary preparation - heating to a certain temperature. For this, a special chamber (2) is provided. It is connected to the distributor by a telescopic duct. Thus, the distributor gradually lowers as the fuel burns under its own gravity and is constantly in the upper burning layer.
- The released pyrolysis gases are burned out in the upper part of the chamber (5). For this, an additional air supply is provided through the damper (4). It has several provisions designed for different types of fuel - coal or wood.
- After the afterburning of gases, the residual products of combustion are discharged into the chimney through the pipe (3).
- The general regulation of the combustion intensity, and hence the heat output of the boiler, is performed by an air damper (1) connected to the bimetallic regulator, at which the set value is set.
- The boiler is enclosed in a water "jacket" for heat exchange with the heating circuit - for this there are pipes for supplying a heated coolant (10) and a "return" (11).
- The inspection window (9) serves for regular cleaning of the furnace from ash deposits.
Video: device and operation of a long-burning boiler " Stropuva»
Some powerful models of Stropuva boilers can be equipped with a forced air fan. However, all of them are quite capable of functioning on natural draft, which makes these heating devices completely independent of the availability of electricity.
The design of the boiler is so efficient that it became the basis for numerous independent developments made by folk craftsmen. So, it was "Stropuva" that probably became the prototype of the popular nowadays. About its structure, correct calculation and technology self-made detailed in the corresponding publication of our portal.
4. The duration of the autonomous operation of the boiler can also be ensured by automating the supply of solid fuel to the combustion chamber. This scheme is implemented in boilers that use granular wood waste as fuel - pellets.
In fact, this is the same long-burning boiler, which has several combustion chambers, but is additionally equipped with a special hopper for loading granular fuel. Continuous feeding of pellets into the furnace is carried out by means of a rotating flexible or rigid auger.
Special photo and thermal sensors monitor the intensity of combustion and the availability of fuel, generating appropriate control signals for the timely supply of pellets to the combustion area in the required amount.
Such a scheme is considered to be very effective and promising. Its main disadvantage is complete dependence on power supply. However, such boilers may well be transferred to the usual manual loading of firewood or coal. The system is quite complicated to install and adjust. And one more disadvantage, which so far limits the widespread use of such boilers - the currently unsaturated market for granular fuel, there may be certain problems with its purchase. Before installing such a boiler, in order not to waste a lot of money, you should guaranteed secure a reliable supply of pellets from their manufacturer.
Video: the advantages of a pellet boiler with automatic fuel supply
Let's sum up
So, it is too early to write off solid fuel boilers as outdated, irrelevant heating equipment. Thanks to modern innovative technologies they got a "second wind" and freely compete with other types of boilers - gas and
- Long-burning boilers have a solid efficiency, reaching up to 90 - 95% in some models. Heat losses, thanks to well-thought-out processes of afterburning of pyrolysis gases and the design of heat exchangers, are minimized. In terms of efficiency and economy, they are in no way inferior to gas ones.
- The emission from such boilers into the atmosphere does not pose a threat to the environment, all components - water vapor and carbon dioxide, are easily absorbed by plants.
- The availability of fuel and autonomy, independence from the availability of gas mains is one of the main advantages of such equipment. There is no need for tedious licensing procedures when installing the boiler. In regions where there is no shortage of firewood, this is the best option for organizing home heating.
- Boilers can have a built-in second circuit for hot water supply to the house. Even if it is not there, it is easy to connect an indirect heating boiler to them.
- Long burning boilers are quite unpretentious and easy to maintain. When used correctly, they are designed to last several decades.
The main disadvantages of such boilers are the following:
- No matter how long the operating time from one load may be, you still have to periodically intervene in this process to replenish the fuel supply to the combustion chamber.
- Unlike or electric, a mandatory preventive measure is the regular cleaning of the boiler from the accumulated ash in order to avoid its coking on the walls of the chambers.
- A solid fuel boiler requires a separate room with good ventilation and a chimney. These devices are always quite massive, so a reinforced platform must be prepared for them.
- Additional space is required to create stocks of solid fuel with the obligatory observance of the rules for its storage. Such boilers are quite sensitive to the level of moisture in the wood. Humidity is considered to be a limiting value of up to 20% - if it is exceeded, a sharp loss of efficiency is possible.