Currently, most owners of private houses have gas heating. However, situations often arise when it is not possible to connect to the central gas pipe. Then solid fuel boilers, powerful and reliable heating devices come to the rescue. You can heat wood or coal both in a private house and in the country. At a cost, this type of heating will be more expensive in comparison with gas heating. In terms of their technical parameters and manufacturability, modern models of solid fuel heaters are practically not inferior to other types of boiler equipment.
Thanks to modern technologies, manufacturers have managed to achieve a significant duration of the combustion process in solid fuel units. The heating solid fuel boiler of long burning is by far the most economical and efficient type of boiler equipment. The undisputed leaders in this class are mine-type solid fuel heating boilers. Such equipment has a simple design, so it is not uncommon for people to try to make a mine boiler on their own.
The principle of operation of the mine-type boiler. Design features
Among long-burning heating boilers, mine-type units stand out for their unpretentiousness to fuel quality. The condition is important, given the fact that other solid fuel heaters are more capricious in terms of fuel choice. Technologically, it is allowed to use logs for the furnace of the boiler, the moisture content of which exceeds 40–45%.
A mine solid fuel boiler is able not only to digest raw firewood, but also to produce the necessary heat for a long time. Between the next loading of fuel, as a rule, 12 hours or more pass. There are models where these figures are even higher.
The unit got its name due to the design features. The combustion chamber or furnace in this device looks like a mine. In units of this type there are two mines: fuel and heat exchange chamber. In the fuel chamber, the fuel is not located in a horizontal position, but is loaded, as in a well, layer by layer. Combustion in such devices is carried out from the bottom up, so these devices are also called units with lower combustion. Let’s see how it looks in practice:
- just before laying, a hearth is created on the grate;
- the main bookmark is already laid on the burning fuel, in layers, from above.
- a constant flow of air mass does not allow the upper layers of the fuel to flare up;
- under its own weight, firewood sinks down, taking the place of burnt logs;
- firewood located in the upper part has time to dry out during the operation of the boiler;
- at the very bottom of the fuel mine, in the absence of oxygen, pyrolysis occurs, the process of formation of wood (pyrolysis) gas.
The second is the combustion chamber or heat exchange shaft, which is the zone where the main combustion process takes place. Pyrolysis gas enters the mouth of the second furnace, which is the main source of thermal energy.
For reference: Pyrolysis is the process of generating a gaseous substance during an exothermic reaction with wood fuel. In the absence of oxygen, a volatile gaseous substance is released during the smoldering process, which then, upon contact with oxygen, releases intense heat.
The furnace shaft may have a different design. Some models of heating devices have a heat exchange shaft with a flat heat exchanger. Often in the design of the heating unit there is a water-heating heat exchanger or a fire-tube heat exchanger installed directly in the furnace shaft. This type and arrangement of heat exchangers is the most efficient. In order to get a real idea of how a mine boiler is arranged, just look at the drawing — a section of the device.
Hot secondary air is supplied to the combustion chamber to increase the intensity of combustion. The walls of the mouth of the combustion chamber are lined with fireclay bricks, thanks to which the highest possible temperature in the furnace is achieved. Fireclay brick not only contributes to better afterburning of pyrolysis gas, but also prolongs the performance of boiler equipment.
It has already been noted above that this type of heating boiler equipment copes well with low-quality fuel. Due to the principle of operation of heating equipment of this type, firewood has time to reach the required humidity parameters. Condensate, which is typical for units of the classical type, emitted in large quantities by wet firewood, is not a hindrance for mine devices. Due to the high performance, the efficiency of such units is 75–80%.
The main advantages and disadvantages of mine-type boiler equipment
For a country house or a country guest house, this type of heating equipment is a real find. It is not always possible to get the ideal fuel to use. Dry firewood in the cold and damp season is a rather rare phenomenon. For other heaters, this state of firewood can cause poor performance of heating equipment. Mine heating devices do not suffer from such shortcomings.
Having installed such heating equipment in your home, you get the following benefits:
- the unit runs on almost any type of solid organic fuel;
- units are able to operate in different operating modes (wide power range);
- equipment is economical. One bookmark is enough for 12–24 hours;
- long and continuous operation throughout the heating season;
- units of this type are energy independent;
- simplicity of design and ease of maintenance (ash is removed during operation of the unit);
- high level of safety of the operating unit.
On a note: Assessing the advantages of mine-type boiler equipment, one should not forget that, like any other boiler, this unit requires competent piping. Otherwise, you risk losing all the benefits of this equipment.
Other disadvantages of this type of boiler equipment include the simplicity of its design. Here you have to be careful and attentive! Incorrect interpretation of the main parameters of the equipment and superficial knowledge of the principle of operation of mine-type boilers can lead to unpleasant consequences.
At first glance, the design of the heating device is simple and straightforward. Many try to make such equipment on their own. Attempts are not always successful due to the fact that it is very important to correctly and accurately position the heat exchangers. In the combustion chamber, the temperature reaches 450–5000With and if the water tube heat exchanger is located low, your boiler will boil instantly, which will lead to sad consequences.
Depending on the design of the combustion chamber, heating devices are distinguished into the following types, according to the names of the creators. The main part of the heating units used in everyday life are Kholmov’s boilers and Efimov’s heating appliances.
How to heat a mine-type boiler
Like any other type of boiler equipment designed for heating residential facilities, a mine boiler has its own subtleties and nuances during operation. The first and most important thing for the normal operation of the unit is the quality of the fuel, and how the firewood is loaded into the fuel chamber. The high thermal efficiency of a solid fuel mine boiler is achieved through proper stacking of firewood. Properly laid fuel will not only ensure maximum working efficiency, but also reduce the likelihood of smoke in residential premises.
The quality of fuel stacking determines the duration of combustion and, accordingly, the duration of the operation of the heating unit.
On a note: the lack of necessary skills leads to the fact that most consumers are not able to properly use the heating device. Instead of the gas generation mode, mine boilers operate in the normal mode. Accordingly, the efficiency of such a unit is extremely low.
In order to properly use a shaft-type heating device, it is enough to learn a simple algorithm of actions.
- The initial ignition of firewood in the traditional way.
- After 15–20 minutes, the boiler will be able to reach its nominal power.
- After the boiler enters the operating mode, the rest of the firewood is loaded into the fuel shaft and goes into the pyrolysis mode of operation.
Properly selected and stacked firewood is a guarantee that the boiler will work for a long time, providing your home with heat.
As for the fuel itself, much depends on the imagination and financial capabilities of the owner of the house. However, despite the fact that shaft-type heaters are omnivores, the efficiency of the boiler directly depends on how you heat the boiler.
Fuel briquettes, woodworking waste, pellets go into the boiler furnace. Briquettes and pellets are considered an elite type of fuel, but their price is much higher than the cost of ordinary firewood. Especially if we take into account the unpretentiousness of mine boiler equipment in terms of fuel resource. Firewood is the main fuel material for mine boilers. During operation, it is necessary to make at least half of the bookmark from firewood.
On a note: it is better to use hardwood firewood for heating the boiler. Pine and spruce logs have a high resin content, which can lead to the formation and accumulation of tar on the walls of the combustion chamber.
Method of stacking firewood in a mine boiler
Having dealt with the principle of operation of shaft-type heating devices, with the requirements for fuel, you need to pay attention to the methods of laying.
The most frequent cases that owners of mine solid fuel boilers have to deal with are associated with hanging firewood in the fuel chamber. The reason for this phenomenon is the wrong bookmark. Taking into account the principle of operation of the mine boiler, where the main combustion occurs in the lower part of the device, firewood should smoothly fall down under its own weight.
Failure to follow the recommendations for laying firewood in this case is fraught with a sudden interruption of the main process — fuel combustion. Before starting the operation of mine units, the following recommendations should be followed:
- logs intended for laying should be smaller, a few centimeters less than the perimeter of the fuel mine;
- firewood must always be laid across the shaft, and in no case along it;
- the driest logs are placed at the very bottom, while damp firewood can be placed at the top.
Some simple tips will help you achieve the normal operation of your boiler. One load of firewood, if all the bookmark rules are followed, should be enough for 12 hours. The boiler will work independently all this time, without requiring your participation.
Mining solid fuel boilers from the entire range of solid fuel heaters are the most convenient, most efficient and most unpretentious in operation. For each of us who has our own dacha or country house, this type of heating equipment will be the best engineering and technical solution.
The consumer is captivated in terms of the choice of heating equipment by the relatively affordable price of mine boilers, a minimum of complex devices and mechanisms in their design.
For the category of consumers who want to get autonomous home heating, solid fuel long-burning shaft-type boilers will provide a lot of free time, a high level of comfort in the house.