Residents of the private sector, owners of country houses and cottages today show an increased interest in solid fuel heating appliances. There may be several reasons for such attention to solid fuel boilers, starting with the desire to achieve independence from centralized energy supply and, conversely, due to the lack of it. The pace of suburban housing construction today is significantly ahead of the rate of gasification of settlements, so the only way out of this situation is cast-iron solid fuel heating boilers.

Why cast iron boilers when there is a wide choice of models of steel solid fuel boilers? We suggest that you familiarize yourself with the design features of solid fuel cast-iron boilers and, accordingly, give an answer to the question posed.

Features of modern cast iron solid fuel boilers

For a country house, solid fuel heating boilers made of cast iron are the best option for a heating device. Residents of private houses install similar units as a backup source of heat in case of extreme circumstances. Both options are justified from the point of view of expediency. Gas heating, despite its availability, is constantly becoming more expensive. There are frequent cases of pressure drop in the gas line. A cast-iron boiler burning coal, wood or pellets will help out in such situations by providing your home with the necessary heat and hot water.

For a residential building located far from power lines, solid fuel becomes the main source of heating. This is especially true in the central and northern regions of our country, where they still dream of central gas supply, and it is considered common practice to heat stoves and boilers with wood. The heating boiler, made of cast iron and running on solid fuel, is experiencing a rebirth today. Having become the successor of the traditional Russian stove, the solid fuel boiler is a high-tech device.

The main advantage that modern models of cast iron heating equipment have is the high power of the units. Some models have power up to 2000 kW. Everything that is at hand goes into the furnace of a solid fuel boiler: firewood, coal, coke, peat, woodworking products and waste. The only point that you should pay attention to, cast-iron boilers are inert devices. The power range of such units is not significant, but in the operating mode, the boiler can produce maximum performance.

Thanks to the introduction of various engineering and technical innovations into the design of boilers, manufacturers have been able to increase the efficiency of units of this type up to 80%. Only pyrolysis boilers have more efficiency, but this is a different story.

For reference: a modern cast-iron solid fuel boiler is a multi-section device. Each section is made of cast iron. By the number of sections, you can judge the power of the heater.


All structural elements have a threaded connection. Seams and interfaces are treated with high-temperature sealants. The manufacture of cast iron boilers and the assembly of equipment is carried out in high-tech production. Such products are made by a special metallurgical method. In the casting process, a cast iron alloy is obtained, in which the percentage of carbon is 2-4.5%. By adding special additives, it was possible to obtain a high-strength alloy resistant to high temperatures.

Due to its design and physical and chemical properties of cast iron, the equipment has a long service life — up to 30 years. This fact captivates many consumers. In comparison with other types and types of solid fuel heaters, a cast-iron boiler is more reliable and has a longer service life.

Long service life is explained by the high resistance of cast iron to corrosion. Cast iron can only be covered with dry rust on the outside, under the influence of external factors.

Models of solid fuel boilers on sale are multifunctional. The cast-iron heat exchanger has a high heat transfer and keeps the required temperature of the coolant for a long time. The inertia of cast-iron boilers neutralizes this plus, making it difficult to adjust the heating temperature of the coolant. Despite this drawback, a boiler with a cast-iron heat exchanger can operate normally at low-temperature operating conditions, which makes it convenient for domestic use.

For reference: In most cases, such heating units are installed in open heating systems, where the circulation of boiler water is carried out in a natural way, due to gravity. A solid fuel boiler made of cast iron can be installed in forced circulation heating systems, however, the operating pressure in the system should not exceed 1.5 bar.

What models of cast iron boilers are produced

Cast iron boilers according to their design features are divided into two generally accepted types:

  • single-circuit;
  • double-circuit.

The first option is a functionally limited type of heating unit. Single-circuit boilers provide only autonomous heating.

Important! Hot water supply in this case is not possible. The way out of this situation will be to connect a water-heating tank to the boiler or install an additional heat exchanger with a large and constant water flow. For normal operation, the installed DHW elements must be tied to the automation of the heating boiler.


The second option is the most common. Many residents of private houses are interested not only in heating, but also in hot water for domestic needs. Cast iron solid fuel boilers in this case are connected to an additional circuit through which hot water is supplied. An additional circuit can be replaced by installing an indirect heating boiler.

On a note: for domestic purposes, a boiler with a capacity of 80-100 liters is selected. The limited volume of hot water and the massiveness of the structure itself is a significant drawback of such an engineering solution.

If you have a constant water flow and in small volumes, a double-circuit cast-iron solid fuel boiler is quite suitable.

Structurally, heating boilers made of cast iron are divided into units with natural draft and with forced ventilation. In the first case, the air inside the residential building is naturally supplied to the working area of ​​the boiler. Combustion products, soot and soot exit through the chimney in the same natural way. The system is designed for small capacity boilers and is suitable for installation in small buildings.

Forced ventilation is a more advanced and reliable design. With the help of a fan, atmospheric air enters the furnace, ensuring the combustion of the loaded fuel. Extractor works on the same principle. The fan creates an additional low pressure zone, due to which combustion products are sucked into the chimney.

The device of a solid fuel boiler in a classic configuration

A boiler in a classic design, solid fuel cast iron is a complex mechanism in which each element has its own purpose and performs certain functions. The high strength of the structure, the reliability of the connections of individual structural elements, ensure the safe operation of the unit.


The number of sections in cast iron solid fuel boilers is always fixed. The diagram shows the device of a cast-iron boiler, the location of the main structural elements. The main components of a cast iron boiler are:

  • sections;
  • branch pipe (chimney outlet);
  • nipples;
  • combustion chamber with a door;
  • ash tray;
  • fans.

Almost all parts and components of the structure are interchangeable, which makes the cast-iron boiler very convenient and practical to maintain. The absence of complex structural products and devices simplifies the operation of the boiler in domestic conditions. The design of the boiler is simple and understandable even to the layman who is not initiated into boiler equipment.

As for the control mechanism, the situation here is ambiguous. Cast iron boilers for coal or other fossil fuels have in most cases a mechanical control system. The main adjustment mechanism is the draft regulator, which is tasked with controlling the decrease or increase in the heating temperature of the coolant. Modern devices, manufactured mainly by foreign companies, are equipped with controllers and blowers

For reference: draft fans are installed on solid fuel cast iron boilers to eliminate the resistance that occurs in the air duct.

Such devices slightly affect the ability of the boiler to be adjusted, however, due to additional equipment, the efficiency of the boiler increases. The combustion chamber and cast-iron sections are not whimsical to the quality of the fuel. Unlike pyrolysis boilers, where dry (maximum 20% moisture) fuel is required, long-burning cast iron boilers can handle any type of fuel, in any condition.

Advantages and disadvantages

Before choosing a boiler for a stand-alone boiler system, the pros and cons should be weighed. Each type of heating device has its own advantages and disadvantages. Solid fuel boilers made of cast iron also have their advantages and their obvious disadvantages.

We have already said that heating equipment of this kind is very inert and difficult to adjust. It takes a long time for the boiler to cool down. When installing the device in the heating system, it is necessary to install an expansion tank, which acts as a temperature regulator for the coolant in the circuit.

A significant drawback, if the operating conditions are not observed, for this heating technique is the fragility of the cast-iron heat exchanger. Such units suffer greatly from mechanical damage, sudden temperature changes and water hammer.

Important! When transporting a new boiler, care must be taken to avoid bumps and falls.


You can avoid damage to the heat exchanger if you follow the operating rules. It is impossible to load cold firewood into the firebox and fill the system of the device with cold water. For reliability, you can install mixing units that play the role of a mixture.

In technological terms, heating appliances with cast-iron heat exchangers are significantly inferior to gas units and other types of solid fuel equipment in terms of thermal efficiency.

Compared to steel appliances, cast iron heaters are more expensive. However, it is not necessary to bring all of these factors together, putting an end to this type of equipment. The advantages of this technique are obvious:

  • long service life;
  • high resistance to corrosion processes;
  • lack of scale inside the heat exchanger;
  • maintainability and manufacturability of the boiler design itself;
  • acceptable dimensions of equipment corresponding to living conditions;
  • high resistance to electrochemical reactions and to a sharp decrease in the temperature of the boiler water.

Summing up

Solid fuel appliances steadily occupy one of the consumer niches among heating equipment. The wide technological possibilities that the new models possess have brought heating devices made of cast iron to a new level.

Today, solid fuel cast iron units are becoming an indispensable attribute of a country house. The omnivorousness of heating devices in terms of fuel, unpretentiousness in maintenance, simplicity of design make these devices competitive in the heating equipment market. The high cost of products should not confuse the consumer. The investment will pay off in full, taking into account the life of the boiler equipment.


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