Despite the fact that most private households are connected to a gas pipeline, the most ancient method of heating a home by burning wood is still in great demand. Heat generators that operate on this ecological fuel are constantly being improved and become more convenient and efficient every day. Engineers managed to increase the burning time of one fuel tab many times over. Thanks to this development, wood-fired boilers for heating private houses appeared.
Features & Benefits
These units, although they are similar to the old archaic solutions, have several serious advantages. So, the design is extremely simple, and there is practically nothing to break in it. In some regions, firewood is not only available, but is also obtained almost for free.
Wood-burning boiler for heating, being untethered from centralized energy supply systems, is completely independent. Therefore, users who have enough fuel for it are insured against a variety of troubles.
Flaws
There are other features that are undesirable. The installation has a large thermal inertia. This means that if you completely restrict air access, the power does not drop instantly. This carries risks - the coolant may boil. A safety valve must be installed in the piping of a wood-burning boiler for the home.
The gases in the smoke contain harmful substances - these are oxides of various chemical elements. Their danger is that when combined with water, they form acids - sulfuric and others. The condensate that forms when the combustion products cool down will be quite caustic. Therefore, experts recommend setting certain limits on the temperature of water or antifreeze in the heating system coming from the return circuit to the heat exchanger. The temperature should not fall below 55 degrees. To prevent such cases, a special unit is installed in the system, which automatically redirects part of the heated heat carrier to the cooled return circuit.
Another feature of wood-burning boilers is the need to periodically clean the inside of the device from combustion products. The chimney also needs to be cleaned. How often should this be done? Experts say that it is necessary to clean the chimney and the wood-burning boiler itself from soot accumulated inside at least once a year.
And finally, one of the most serious drawbacks is that the fuel is placed entirely by hand. You need to do this often. To maintain a comfortable temperature,it is necessary to lay new firewood every 3 hours. The body of these boilers does not have a high heat capacity - this is not a Russian stove, which is heated once a day. Engineers had to work hard to ensure that the unit worked longer on one tab. Such a system is called a long burning wood boiler.
Operation principle
There are several schemes for the operation of these heating systems. Let's consider each separately. The difference is in how the fuel is stacked and how it is ignited.
Stowing fuel in a column and firing from above
Firewood will burn the longest if set on fire from above. So, the fuel will burn in the direction from top to bottom. Wood-fired boilers operating on this principle are called upper combustion boilers. To prevent the flame from spreading quickly through the fuel, air is supplied only to the combustion zone. For this, the design has special telescopic air ducts.
This is how systems with a long firebox work. But firewood here is set on fire not from above, but from the side of the boiler. Such solutions are much less common, as they have large overall dimensions.
Wood pyrolysis
This is another principle on which wood-fired boilers work for a long-burning home. The peculiarity of this principle is that it is not the wood itself that is used as fuel, but the gas obtained as a result of pyrolysis.
When heated to high temperatures and in conditions of limited air access, long chains of organic wood particles become short. ATas a result combustible gases are formed. In our case, this is the so-called wood gas. Then, through the nozzle, it is fed into the second chamber of the boiler, where it burns out. Air is introduced into the chamber and the gas is ignited. Such wood-burning boilers are called pyrolysis.
Unit with automatic ignition system
This is another variant of the popular wood burning boilers. They take an ordinary wood-fired heat generator and equip it with a nozzle with a damper and an automatically controlled fan. In the process of burning firewood, the fan pumps air into the combustion chamber. When they are warm enough, the automatic cuts off the oxygen supply.
The open damper will close under its own weight. As a result, the flame will go out. When the water in the system or antifreeze cools down to certain temperatures, the automatic system will start the fan again, it will start supplying air again - the fuel will ignite.
Restriction of air supply for smoldering firewood
This mode of operation of a wood-burning boiler for heating a house has a lot of disadvantages. In this case, combustion is not carried out completely - the efficiency of the system is very low. During operation, a huge amount of soot is formed, and black smoke comes out of the chimney. Since the fuel does not burn completely, condensation forms - it is caustic and poisonous. At the same time, there is quite a lot of it.
But despite the shortcomings, wood-fired boilers based on this principle (and these are the famous Bulerian stoves) are widely used in the field. They are autonomous and do not require electricity.
Features and Specifications
Modern wood-fired boilers can not only provide heating, but can also heat water. There are two types of heat generators. There are two- and one-loop solutions.
Double-circuit wood-burning boiler for heating a private house has an additional heat exchanger. It is designed specifically for heating water. When the second circuit becomes active, the automation will supply the hot coolant not to the heating pipes, but to the heating of the second circuit. Such a unit is a flow heater. But at the same time, heat does not enter the heating system.
Single-circuit boiler is a system with the function of connecting indirect heating boilers. This boiler is a storage tank with a coil inside. The coolant circulates through the latter before entering the heating system. This option is more convenient for domestic use.
Popular models
Many people think that among the manufacturers of wood-burning boilers for heating a private house, European brands are in the lead. Actually it is not. Russian models are more popular. They are much cheaper and no less high quality compared to their European counterparts.
One can single out the products of the domestic manufacturer Prometheus. The power of this equipment ranges from 10 to 50 kW. You can choose a model for heating a small cottage or a large house. The body material is made of steel. The boiler can work not only on wood, but also on coal.
Russian production of "KMCh" is also popular. This is a multi-fuel equipment. It works great on gas, diesel, wood and coal. It is purchased by people who are not yet sure what kind of heating to carry out.
There are quite a few European brands. So, Czech cars Buderus Logano occupy worthy first places in the heating equipment market. The boiler is considered universal. It can work not only on wood, but also on gas. This is a good option for those who have problems with gas supply. If it is suddenly turned off, the house and its inhabitants will not freeze.
Lithuanian Stropuva products are used in houses with high ceilings. But one should not think that the cauldron is something formless. This is an elegant design that will fit into any interior. The burning time on wood is 80 hours. This is true, although it seems unbelievable. Please note that the boiler is large enough.
How to choose a unit?
To correctly choose a wood-burning boiler for a private house, you should know the power. It is equal to the heat losses that are typical for heated rooms during the coldest periods of the year. This leakage can be determined using thermotechnical calculations. They take into account the material from which the house is built, the temperature difference inside and outside, the area of window openings, the orientation of the building in relation to the cardinal points.
These calculations can be ordered from qualified engineers. Butyou can calculate everything yourself - how this is done is indicated in the relevant SNiPs.
Very often recommended power is one kW for every 10 square meters. This is an approximate figure, and it is relevant only for regions in the middle zone of the Russian Federation.
Efficiency will be maximum only when the boiler is in operation. Therefore, to save money, it is recommended to buy two units - one for medium temperature, and the second - low-power. The latter will help the big boiler in the cold winter and will also work between seasons. In this case, each unit will operate in nominal modes.
The most important part of any boiler is the heat exchanger. Cast iron products are considered the most reliable. They are not subject to corrosion, and the service life is 20-25 years. Heat exchangers made of steel have a lower price, but the strength is less - the welds are to blame. The service life will be no more than 15 years.
Appropriateness of installation
The use of wood-burning boilers in the heating system will be appropriate when it is completely impossible to connect gas or use any other coolant. Firewood is a non-renewable source of energy. But if there is access to free raw materials in large quantities, the preparation of firewood still requires an investment of time, effort and money. It's not always as cost-effective as it might seem.
However, if the boiler is installed in the country, then this is quite an effective option. At the dachas, people are infrequent and come for a short time, which means that a lot of fuel is notneed. If you need to heat a large room, then it is best to purchase multi-fuel solutions or a long-burning boiler. Such units will cost a little more. But they are very versatile. In the absence of one type of fuel, you can always use another. If a regular wood burning boiler is used, this feature will not be available.
