Which fuel is better for a solid fuel boiler?

Author - Valery Zubov

expert category: Everything for the garden

It is known that different types of wood have different heat transfer and combustion types. Some burn slowly, releasing the maximum amount of heat and creating almost no smoke, others burn quickly, produce little heat, and need to be refilled every hour. At the same time, it is important that the process of chopping wood is as simple as possible.

Let's figure out which logs are appropriate to burn and where: how to heat a stove or fireplace, heating system or sauna to achieve the best effect.

What kind of firewood is best to prepare for heating a house?

Heating material for home heating must meet certain criteria:

1. The main measure in the process of choosing firewood for heating a private house is the density of the wood. This property ensures long-term combustion and smoldering, and, accordingly, heat transfer. Firewood made from hardwood is considered to be the most nutritious:

In addition, in some areas people use rare wood that is not popular for burning: cherry, walnut, hawthorn and other types of fruit trees.

Interesting: Hawthorn logs, according to the observations of experienced stokers, have greater efficiency than oak (hornbeam, beech) firewood. When they burn, the cast iron grates melt in the boiler. The efficiency of these logs can be compared to coal.

2. Another important indicator of the use of firewood is the volume of smoke and ash emitted during the combustion process. It is known that when burned, coniferous trees smoke strongly, which is due to the presence of resin in them. Thus, to heat a home boiler, it is better to prepare deciduous logs. Using them, you will save yourself the unnecessary hassle of cleaning the boiler and chimney from soot and soot.

Experienced stokers advise heating the boiler with wood from:

• oak (beech, hornbeam);
• birch;
• acacia;
• ash;
• alders;
• aspen;
• and you;
• poplars;
• pine trees

At the same time, with the hardest firewood, you need to use lighter species for ignition, for example, it is better to light oak with alder or pine.

Tip: Hardwoods are easiest and fastest to harvest using log splitters and sawmills.

3. It is also necessary to consider how often you will load firewood into the boiler. Here it is obvious that it is better to use wood with a long period of burning and smoldering. In this case, the output temperature should not be very high. Types of wood such as oak, ash and birch (the best option) are useful here. Aspen, spruce and pine are also suitable. 4. How much will this or that timber cost you? The options here are varied. Someone can independently prepare dead wood on their site or use waste material. For those who buy firewood, pay attention to:

• humidity: it is better to take dead wood or dry fresh wood for at least a year;
• method of stacking firewood: if you were brought a truck of bulk, loosely stacked timber, then when calculating, the volume declared by the seller must be multiplied by a factor of 0.8, otherwise you will overpay the seller by about 20% of the cost.

Important! By heating the boiler with aspen and alder logs for 24 hours, you can clean it of the combustion products of other firewood. This is what our ancestors did. At the same time, it must be well dried, the humidity should be no more than 19%.

How to heat a solid fuel boiler

The choice of a heating boiler, as a rule, occurs at a minimum of primary and operating costs, taking into account the availability of a particular type of fuel. Boilers running on wood fuel have an advantage over boilers running on other energy sources, since the cost of firewood remains almost unchanged, while the cost of gas, diesel fuel and electricity is constantly growing. But after choosing a solid fuel boiler as a heat generator, the consumer is faced with the question of what kind of wood is best to burn it with in order to obtain the maximum possible amount of thermal energy at an acceptable cost and reduce the costs associated with servicing the boiler.

Before talking about the properties of certain types of wood and recommendations for their use, it is necessary to talk about the general principles of burning wood in pyrolysis boilers.

To ensure the most complete combustion of wood, it is recommended to place at least half of its volume in the firebox. This is due to the fact that with a decrease in the volume of simultaneously burning firewood, the average temperature in the firebox decreases and the percentage of unburned pyrolysis gases increases, which ultimately leads to a decrease in the efficiency of the boiler.

To ensure high efficiency in pyrolysis boilers, it is important to use dry firewood, since heating and evaporation of the moisture contained in the firewood requires significant thermal energy, which is irretrievably carried away with water vapor by flue gases into the atmosphere. The presence of water vapor, which absorbs thermal energy, reduces the temperature in the combustion chamber, which ultimately leads to incomplete combustion of pyrolysis gases and an increase in losses from chemical underburning. Therefore, the use of raw firewood leads to a significant reduction in the efficiency of the boiler. In addition, water vapor contributes to the rapid growth of tar and soot deposits, and in some cases, condensation in the chimney. Therefore, in addition to air-drying firewood outdoors under a canopy, it is recommended to additionally dry the firewood in a heated room.

For more economical burning of firewood over a long period of time, it is necessary to choose large fractional logs or logs of appropriate length. This is due to the fact that the surface layer of wood burns predominantly, and the smaller the surface area of ​​the firewood with the mass required to fully load the firebox, the smaller the volume of simultaneously burning fuel and the longer it will burn. The fact is that the larger the volume of simultaneously burning fuel, the more it is necessary to limit the intensity of its combustion by reducing the flow of oxygen into the furnace in order to prevent overheating of the coolant in the boiler or operation at low power. In this case, combustion occurs with a lack of oxygen, as a result of which the pyrolysis gases do not burn completely and heat losses proportionally increase due to chemical underburning.

Since the duration of combustion is largely determined by the mass of loaded firewood, it is necessary to use tree species with denser wood, which is typical for deciduous trees. Coniferous wood has a lower density and a significantly higher resin content, which complicates the maintenance of the heating boiler. Below are some of the wood species found in our country that can be used as fuel.

In conclusion, we note the specifics of combustion of various types of wood:

• oak is one of the leaders in terms of calorific value and combustion duration. The calorific qualities of middle-aged oaks are better than those of old and young trees;
• Birch firewood ignites quickly and can burn with a high moisture content. However, they contain a lot of resin, which can settle in the form of tar on the heat exchange surfaces of the boiler and the chimney, especially when the boiler operates at low power;
• aspen, alder - during combustion they emit a small amount of soot and for this reason can be used to partially clean the chimney of soot by burning it out and operating the boiler at outputs close to maximum;
• poplar - burn well, but burn out quickly, have the lowest combustion temperature - about 500 0C;
• pine - burn hotter than spruce due to the larger amount of resin. Disadvantage: resinousness;
• beech and ash are more difficult to light, but they can burn if they contain high humidity. In addition, this firewood has the highest combustion temperature - more than 1000 0C, which contributes to more complete combustion of wood and increased boiler efficiency.

Thus, taking into account the above recommendations for the selection of firewood and the rules for their use will significantly increase the efficiency of the heating boiler and save significant funds on its operation.

How to heat a boiler correctly

To ensure maximum efficiency during the combustion process, I’ll tell you what you need to do and what you shouldn’t do:

1. Adjust the draft according to the instructions to the desired temperature;
2. Light and heat the change;
3. The upper chamber of the firebox must be cleared of ash and soot and burnt material;
4. Place new firewood, keeping a small distance between them.

It is recommended that logs intended for the fire be brought in and stored near the boiler so that they lie for 10-14 days and evaporate excess moisture. The space near the boiler must be regularly cleaned of dust, chips and bark that has fallen from the wood.

To maintain the boiler efficiency at a high level, it is necessary to systematically clean the heat exchanger from soot. Every cubic meter burns a bucket. It is necessary to ensure the stable operation of the circulation pump; in the event of a sudden power outage, the boiler may deteriorate.

The most important condition for a successful fire is good drying of the wood. The calorific value of damp wood is reduced by up to 2.2 times. For this reason, it is strictly forbidden to burn with raw wood. This iron rule is also relevant for the stove, for the fireplace, for the bathhouse. However, there are some differences and nuances that affect the success of the fuel process in these centers. I'll tell you about them below.

Interesting: To check the degree of dryness of the firewood, you need to run your hand along the cut of the log; it should slide freely without stopping on the wood. You can also knock the logs against each other. Dry material sounds loud, while wet material makes a dull sound.

Types of boilers operating on solid fuel

All equipment of this class can be divided into 2 groups:

• Automatic fuel supply
• Manual loading

The first are pellet boilers. In them, granules play the role of fuel; they are loaded into special bunkers and from there they enter the furnace. Such devices have high efficiency and can operate automatically for weeks, without human intervention.

The latter, depending on the design features, are divided into 3 types:

• Classic
• Pyrolysis
• Long burning

They can use firewood and wood waste as fuel.

A traditional or solid fuel boiler using wood has been produced for a very long time, and its design has remained virtually unchanged. In it, the combustion chamber is located at the bottom and is considered the hottest part. Most often it is made of cast iron or steel. However, such heating of a wooden house with a solid fuel boiler is used quite rarely, as it requires frequent maintenance.

Pyrolysis devices are a new step in the field of solid fuel equipment. Their work is based on the principle of decomposing wood into solid residues and gases and burning the latter. The advantages of this device include high efficiency, minimal formation of ash and soot. Among the disadvantages is the need to burn dry wood with a humidity of no more than 20%.

Long-lasting combustion - their operating principle was developed in Russia and has no analogues in the world yet. It is a new generation boiler not only in terms of design, but also in its operating principle. Its main advantage is the simplicity of its design and the ability to service it once a day when operating on fuel with natural humidity. A solid fuel wood boiler has the most precise power control and can produce a given amount of heat.

What kind of wood is best to heat the stove?

1. The best firewood for the stove is oak, birch, ash, and acacia.
2. Conifers are accessible, inexpensive, easy to prick, and burn well. At the same time, they have a number of disadvantages: rapid combustion, low calorific value, high resin content. It is better to heat a stove with this material in combination with oak.
3. Oak (hornbeam, beech, elm) burns longer than all other tree species, and its coals smolder for hours, maintaining a high temperature. Since its price is so high, it is ideal to use in combination with pine or other inexpensive wood.
4. Birch is considered to be the optimal timber material. It is easy to heat the stove with wood, the price is affordable, and it is easy to prepare. It is good to heat the stove with wood + peat briquettes. Wood gives off heat, and briquettes maintain it well through long-term smoldering. Instead of birch, well-dried maple may be suitable.
5. Acacia is a worthy alternative to oak and birch. Here you need to take into account that you will have to work hard to split acacia, but it tends to smolder for a long time.
6. Experienced stokers advise heating the stove with ash wood, the combustion temperature of which reaches 1400 degrees. Among domestic wood, this is the highest temperature, while for oak it averages 900 degrees, and for birch - 820 degrees. At the same time, ash is the only type of wood that can be used raw, since it contains a minimal amount of moisture, and dried logs do not become damp.
7. American maple can be a good budget material. Its advantages: high calorific value and absence of soot, widespread availability, has no value as industrial wood.
8. Willow and poplar are cheap, but they are not worth buying, since their structure is loose, they burn quickly and provide little heat. Such a waste of money will be in vain, and the heating process will be very troublesome and time-consuming. Poplar is difficult to saw, even with a chainsaw, it breaks chains and is difficult to prick, and besides, you will have to be on duty at the boiler.

Important! With a strong air supply, ash firewood can lead to burnout of the grates and stove dies. Here you can resort to combining ash with other types of firewood.

Choosing a boiler

Let's note what you need to pay attention to and what to follow when purchasing such equipment:

1. Design feature.
2. Loading capabilities.
3. There is a need for electricity consumption.
4. How many circuits are there in the boiler?
5. What material is the heat exchanger made of?

See also:

How to make ventilation in a private house? https://euroelectrica.ru/kak-sdelat-ventilyatsiyu-v-chastnom-dome/.

Interesting on the topic: Vibrating rammer: how to choose?

Tips in the article “Where are folded sieves used?” Here.

When purchasing, be sure to pay attention to the manufacturer, and trust and buy only from time-tested ones.

How to light a stove

1. Check the operation of valves and dampers. Inspect the chimney and clean it of soot.
2. You need to light the stove quickly with light wood so that the flammable gas does not have time to disperse and the main wood can ignite. This process is regulated by furnace valves and the ash door. Therefore, paper, brushwood and other flammable materials are first used. The valve must be open and the ash pan closed.
3. The main logs are laid so that there are a few centimeters between them for air circulation (in a cage or horizontal rows). In this case, the firebox cannot be filled to capacity.
4. After the firewood has ignited, the ash door opens completely. And then the hearth is regulated by closing the door and the valve.
5. Additional loading of firewood is done as needed, similar to the first loading. To prevent the combustion process from being interrupted, the coals from the decayed material are raked into the center.

Important! To prepare firewood for the heating season, it must be harvested in winter.

Adjusting the temperature of a solid fuel boiler

The efficiency of a heating system depends on a uniform temperature supply. And if in gas and liquid fuel boilers this issue is resolved by continuous fuel supply, then in solid fuel boilers there is no such possibility. And the solid fuel itself, when burned, releases its temperature unevenly: at the beginning and end of combustion, the portions of firewood are smaller, in the middle of the process – more.

A system for regulating the intensity of fuel combustion, that is, the supply of air necessary for combustion, helps to partially solve this problem.

Thermostatic draft regulator

The boiler doors have seals, so air enters under the grates through the lower damper. The amount of opening of this blower flap is controlled by a thermostatic draft regulator .

Thermostatic draft regulator. Photo from cotlix.com

The required temperature is set on it, and the regulator itself is mechanically (by a chain) connected to the blower door. If the temperature is insufficient, the regulator slightly opens the blower door; if it is too high, it closes it.

You need to understand that a solid fuel boiler is a very inert device, and the draft regulator controls the combustion process with a large error. Therefore, the entire heating system must be designed taking this feature into account.

Fan and controller

A smoother adjustment of the combustion process is possible using a fan that pumps a specified amount of air into the firebox. The number of revolutions of the device blades is regulated by a controller that takes into account the readings of the temperature sensor and the value of the temperature set by the user.

Shiber

A damper is a damper on a chimney, otherwise called a throttle. The damper is installed after the boiler and blocks the chimney channel. Whether it needs to be installed or not depends on the equipment model. Some types of boilers are equipped with a damper as standard; in other cases, manufacturers may recommend installing an additional damper in the chimney.

The damper allows you to increase the efficiency of the heating device by partially blocking the chimney and reducing the rate of removal of heated combustion products. How much to open or close the damper can only be determined experimentally, because it depends on the outside air temperature, humidity, atmospheric pressure, wind direction and strength.

Properly selected heating equipment, and most importantly, its effective use, will bring warmth into the house, and the owners will only need to supplement it with home comfort.

Damp firewood is quite suitable for kindling if done correctly. However, you can only light a stove with raw wood occasionally, since when igniting raw wood, a large amount of soot is formed, which settles on the walls of the stove and in the chimney. The condensation that forms over time reduces the strength of the walls of the stove if it is made of metal.

What kind of wood to heat a bathhouse with and how

The purpose of lighting a bathhouse is to heat the room to high temperatures in a short time. To achieve this, dense tree species that can heat up the stove and stones are well suited. Important here are the smell of wood and its effect on human health.

In order for the bathhouse to be beneficial, it is good to select dry, but not old, oak, birch, pine firewood, and the age of the wood should be average. The following are considered good bath timber:

• oak;
• birch;
• Linden;
• alder;
• pine;
• maple;
• fruit trees.

Such firewood is especially good for black baths. It is better to chop lumps immediately before kindling. Start lighting with small wood chips and be sure not to load the stove to capacity.

What kind of wood is best for burning a fireplace?

All types of wood are suitable for a home fireplace. The principles for choosing logs are the same as for the stove. The best are hardwoods. Light the fireplace

not difficult. The main task is to adhere to several rules. To do this you need:

• use firewood several centimeters less than the depth of the fireplace;
• for ignition, use dry wood chips, piled up, paper, etc.;
• arrange the rest of the firewood on top according to the “pioneer fire” principle;
• If the fireplace has a strong draft, the hearth can be lit from above by moving the seed to the top.

In order not to suffer from incineration, it is important to promptly check and clean the fireplace and chimney, do not close the damper completely during combustion, and, if possible, use logs without bark.

Important! You cannot light a fireplace with coal or liquid fuel.

What is more profitable: firewood, pellets, briquettes or coal

A detailed analysis of all indicators of alternative fuels is a separate big topic. Here it is inappropriate to analyze only the cost of 1 kWh/kg. An important criterion when selecting fuel is ease of use and complexity.

Let's briefly look at pellets and briquettes:

1. Pellets. The cheapest ones are black, made from sunflower. They have low heat transfer and produce a lot of ash, but not all boilers can be fired with them. They are tough only for expensive European boilers with high-quality burners. Budget pellets are made from mixed wood species with the addition of husks and other combustible impurities, and have average caloric content and ash content. As a rule, they are gray in color. The most expensive ones are white. They are made from hardwood without bark, adding anthracite, which significantly increases heat transfer. Such pellets are tightly compressed, and their ash content is below 1%, which significantly reduces their consumption. When using this material, you will have to pay the same amount at the end of the heating season, but having bought high-quality pellets , you will add to the boiler less often.
2. Briquettes are made from boiled sawdust of different types of wood by pressing and drying. In this process, the wood gets rid of all non-combustible components. Unlike pellets, they are pressed weaker using different technologies. This fuel burns for a long time and has a low ash content. Basically, they heat pyrolysis boilers. However, they are successfully used in baths, fireplaces, etc.

As for coal, recently the quality of this raw material leaves much to be desired. Good anthracite is rare, it costs more than good firewood, and besides, it cannot be used in all boilers, not to mention fireplaces, sauna stoves, etc.

Today, firewood remains the most optimal way to heat a private home in terms of price/quality ratio in the absence of gas. The conclusion is this: it’s better to heat with wood! Oak firewood burns no faster than coal, and retains decent smoldering. I told you what they can be replaced with, but what is more convenient - firewood or pellets or briquettes - it’s up to you to choose.

If you have any questions after reading the article, please leave a comment below. I will be happy to answer them!

Solid fuel boilers of various types. How to heat them correctly?

While the theoretical part is a bit clear, in practice the situation looks different. There is no general template for how to heat a solid fuel boiler with wood. Each solid fuel heating device has its own specifics and nuances. This concerns not only fundamental differences in the operation of units, but also the smoother choice of fuel. We mainly deal with three types of wood-fired boiler equipment. These are the following types of solid fuel boilers:

• pyrolysis type units;
• long-burning wood-burning boilers;
• classic heating devices.

In addition to the difference in operating principle, many heating devices differ in the way they load fuel. There are models with manual loading of firewood, as well as products in which this process is semi-automated.

Let's consider the situation with firewood for each type of heating device.

Pyrolysis boilers. What is the situation with firewood for boilers of this type?

Ignition of a pyrolysis type boiler is based on the principle of operation of the unit. Accordingly, a scheme for supplying fuel to the combustion chamber emerges from here. This type of heating device has two compartments. One contains materials for kindling: paper, wood chips, brown coal. The firewood itself is already stacked in another compartment. The combustion of the main fuel load occurs at a temperature of 450 0 C. To begin with, you can add an incomplete volume of firewood. After the flame burns, the remaining logs are laid.

Important! Pyrolysis boilers operate only on dry wood. The humidity of the fuel material should not exceed 7-8%. Otherwise, pyrolysis will not occur - the main feature of this type of boiler technology.

After the fire has ignited in the kindling chamber, the main work of the heating device begins. The high efficiency of the unit depends on the condition of the chimney. For pyrolysis boilers, it is necessary to have a cleaned and heated chimney.

How does a long-burning heating device work with wood?

Among the range of heating equipment, long-burning boilers occupy a significant place. These are the most efficient and productive devices, specifically designed for heating residential buildings. The main feature of such equipment is their enormous operating time. A well-functioning unit is capable of operating for a long time in normal operating mode from one load of firewood. The intervals between downloads are up to 8-12 hours. With foreign models you can achieve even better results.

Long-burning solid fuel boilers are not particularly fancy. They can be heated with ordinary wood, again dry. Paper and wood chips are used for kindling. Unlike other boilers, where combustion occurs from the bottom up, in these units everything happens the other way around. Fuel is added in even layers into the upper chamber. After the paper and small wood chips have ignited, we install a press equipped with an air distributor on the topmost layer of logs.

The press puts pressure on the wood, causing it to smolder slowly rather than burn with a bright flame. Due to this, a longer burning time for this type of equipment is achieved.

The sequence of kindling a conventional solid fuel unit is no different. Here, as is the case with newer, modern units, it is important to use dry firewood. Methods for laying firewood are determined by the size of the combustion chamber and the fuel combustion process itself. An air-type wood-burning boiler is nothing special in terms of fuel loading.

Classic solid fuel boilers are of the least interest, since this type of heating equipment is unpopular today.

Important! Under no circumstances should you use flammable and flammable substances such as gasoline, diesel fuel, and various chemicals when lighting solid fuel boilers.