How to choose a solid fuel boiler with high efficiency: review of models and prices

Solid fuel boilers with high efficiency, designed for heating water, heating residential premises, buildings for various purposes, can operate efficiently and effectively under any conditions. Their performance directly depends on the design features and the method of fuel combustion.

The parameter that determines the quality of heat transfer during operation is efficiency (coefficient of performance). This indicator displays the ratio of the energy released during long-term combustion to the useful heat released, which provides the entire system. It is expressed as a percentage, and the value depends on the quality of the boiler’s operation: the better the unit functions, the higher the efficiency.

Construction of a solid fuel boiler

The design of the solid fuel boiler is such that it can operate on both wood and coal. What is noteworthy is that to install these units you do not need to obtain an installation permit. In addition, they do not need frequent checks and examinations with the invitation of specialists. Typically the unit has a cylindrical or rectangular shape.

Components present in all boilers:

1. Furnace or combustion chamber. Firewood is placed in it and then burned. Due to this, heat is generated.
2. Blower (ash pan) is a hole that allows air to pass through to the combustion site. It is part of the firebox and is separated from it by a grate, through the cracks of which the slag remaining after the combustion of firewood pours out.

The operating principle of a new type of boiler is based on pyrolysis combustion of fuel. In them, the process of obtaining thermal energy is more complex, but effective.

In pyrolysis boilers, flammable gas is released, obtained during the decomposition of wood under conditions of lack of oxygen. This steam is mixed with air and burns with a torch in the heat exchanger zone. The design is equipped with a loading chamber and a firebox.

After placing coal or firewood in the loading chamber, the raw material enters through a ceramic burner into the combustion chamber, where a torch is located at the outlet. Adjusting the gas supply allows you to keep the coolant temperature at 65–68 ºС.

The heat exchanger is one of the most important components of a high-efficiency boiler. Heat is transferred through the walls of its tubes. By design, the heat exchanger resembles a coil, which is located in the flame zone of the combustion chamber. With new units, in most cases, it is designed so that the firebox itself is located inside the coil, thereby reducing heat loss.

Heat exchangers are divided into two types:

1. Steel. Such units are quite lightweight, easy to install and inexpensive. However, their service life is about 10 years. Cannot be repaired.
2. Cast iron. They are characterized by a long service life - over 20 years. Such boilers are resistant to corrosion. If one of the sections breaks, you can replace it with a new one.

How to increase the efficiency of heating equipment running on solid fuels

Today, many consumers, having at their disposal a solid fuel boiler, are trying to find the most convenient and practical way to increase the efficiency of heating equipment.
The technological parameters of heating devices set by the manufacturer lose their nominal values ​​over time, so various methods and means are being sought to increase the efficiency of boiler equipment. Let's consider one of the most effective options, installing an additional heat exchanger. The task of the new equipment is to remove thermal energy from volatile combustion products.

In the video you can see how to make your own economizer (heat exchanger)

To do this, we first need to know what the temperature of the smoke at the outlet is. You can change it using a multimeter, which is placed directly in the middle of the chimney. Data on how much additional heat can be obtained from evaporating combustion products is necessary to calculate the area of ​​the additional heat exchanger. We do the following:

• we send a certain amount of firewood into the firebox;
• We measure how long it takes for a certain amount of firewood to burn.

For example: firewood, in the amount of 14.2 kg. burn for 3.5 hours. The smoke temperature at the boiler outlet is 460 C.

In 1 hour we burned: 14.2/3.5 = 4.05 kg. firewood

To calculate the amount of smoke, we use the generally accepted value of 1 kg. firewood = 5.7 kg. flue gases. Next, we multiply the amount of wood burned in one hour by the amount of smoke produced by burning 1 kg. firewood As a result: 4.05 x 5.7 = 23.08 kg. volatile combustion products. This figure will become the starting point for subsequent calculations of the amount of thermal energy that can be additionally used to heat the second heat exchanger.

Knowing the value of the heat capacity of volatile hot gases as 1.1 kJ/kg, we make a further calculation of the heat flow power if we want to reduce the smoke temperature from 460C to 160 degrees.

Q = 23.08 x 1.1 (460-160) = 8124 kJ thermal energy.

As a result, we obtain the exact value of the additional power provided by volatile combustion products: q = 8124/3600 = 2.25 kW, a large figure that can have a significant impact on increasing the efficiency of heating equipment. Knowing how much energy is wasted, the desire to equip the boiler with an additional heat exchanger is completely justified. Due to the influx of additional thermal energy for heating the coolant, not only the efficiency of the entire heating system increases, but also the efficiency of the heating unit itself increases.

What is efficiency

The efficiency factor of heating equipment is an indicator that is determined by the ratio of energy spent and useful heat entering the heating system for transportation to the room.

The efficiency percentage is calculated using the following formula:

q 1 + q 2 + q 3 + q 4 + q 5 = 100%

Explanation:

• q 1 is an indicator of the heat that was transferred to the coolant - water;
• q 2 - physical underburning - heat loss with exhaust gases;
• q 3 - chemical underburning - heat loss due to incomplete combustion of fuel;
• q 4 - heat loss during heat dissipation.

The efficiency of a solid fuel boiler will increase subject to optimized operation of the equipment.

High-quality installation, choice of raw materials, availability of ventilation and operating conditions significantly affect the efficiency indicator.

What does it depend on

Efficiency mainly depends on the loss of useful heat resulting from underburning of gases that are released during fuel combustion, as well as on the quality characteristics of the fuel and the amount of thermal energy released into the chimney.

The efficiency indicator depends on a number of factors:

• technical condition of heating equipment;
• load on the heating system;
• quality of fuel used by heating equipment.

Why is the efficiency higher in steel boilers?

In steel boilers, unlike cast iron ones, the efficiency will always be higher, since they require little energy input to heat a certain volume of water to the required temperature.

Steel is a less brittle material than cast iron, so in metal heating units it is possible to design a combustion chamber of a more complex geometric shape. Due to this, the heat exchange area increases, which leads to increased efficiency.

Steel units are characterized by fewer technological limitations. They allow you to increase efficiency by improving the design: adding convection channels, cooled grates, and increasing the reliability of the heat exchanger.

Due to high-quality insulation, steel boilers retain heat better. Two days after the unit is turned off, the temperature of its walls decreases by only 20 degrees.

Radiator installation

To maximize efficiency, you need to install radiators so as to heat the room as much as possible. Heat loss should be minimal. The window sill should cover the top of the battery 2/3. The distance from the top of the section to the window sill is 1 meter, from the floor to the radiator – 1m 20 cm. From the wall to the panel on the radiator (rear part) – 2 cm. Heat flows will partially linger near the window sill, heat the wall, and reduce heat loss through the window.

The coolant also needs to be selected correctly. Antifreeze has a low energy content. Therefore, it is better to fill the pipes with distilled water. You can change the burner from an old model to a new one to improve safety and gas consumption. Systematic pipe cleaning will increase efficiency. Several methods are used for this: chemical, hydraulic or a combination. It is necessary to install mirror screens behind the batteries. Even regular dust removal will improve heat transfer.

Operating rules affecting the boiler efficiency value

To ensure that heating equipment always works properly, experts recommend adhering to the basic operating rules that affect the efficiency of the boiler.

In this case, it is necessary to strictly follow these points:

1. Select only the optimal modes of blowing and operation of the hood.
2. Monitor combustion intensity and completeness of fuel combustion.
3. Constantly monitor the amount of drift and failure.
4. Assess the condition of surfaces that heat up when fuel burns.
5. Clean equipment regularly.

Boiler selection criteria

Before installing a heating system, you need to decide on the type of boiler, find out what power equipment is needed to heat the entire area of ​​the room, and choose the type of fuel.

When choosing, you should pay attention to the following criteria:

1. Boiler power / useful volume of the loading chamber. This indicator indicates how much fuel can be loaded into the combustion chamber and how often this will need to be done. With the same dimensions, cast iron products demonstrate increased power.
2. Dimensions. Cast iron equipment with the same power as steel equipment will be more compact and will require on average 19% less free space for installation.
3. Type of fuel. It is advisable to purchase boilers made of high-alloy durable steel if coal will be used as the main fuel. To use firewood, the ideal option would be a unit with a cast iron chamber.
4. Unit weight. A cast iron boiler weighs approximately 17% more, so the price for delivery and installation of this device will be significantly higher.
5. Impact strength. Steel is more ductile than cast iron and therefore the risk that a metal boiler will receive damage and cracks during loading or transportation is several times lower.
6. Durability. The service life of a solid fuel unit is 10–20 years. The duration of operation depends on compliance with the manufacturer's recommendations. In practice, with proper maintenance, any device can work much longer.
7. Price. Steel units will have a lower price compared to cast iron products of the same class and power. The technology for processing sheet steel is less labor-intensive.
8. Service. Cleaning heat exchangers in steel boilers is easier than cleaning cast iron products.

You can also make a homemade solid fuel boiler.

Instability of solid fuels

Let's consider what is the instability of coal or wood as fuel. Let's start with coal.

There are countless different grades of coal offered on the market. Each brand differs in structure, chemical composition and moisture content. It can consist of both large pieces and small particles, and all of them can be mixed in different proportions. Accordingly, the calorific value of coal will be different each time. Accordingly, the efficiency and power of solid fuel coal will also be different.

If we talk about firewood, the situation here is exactly the same. Logs have different sizes, are stored at different air humidity, which means their ability to generate heat will be different. So, for example, if at a wood moisture content of 15%, its calorific value will be approximately 4.3 kWh per kilogram, then at 20% it will already be less than 4 kWh per kilogram. With higher humidity this figure will be even lower.

Naturally, with such variations, guaranteeing the exact efficiency and power of a solid fuel boiler equal to 90% is, to put it mildly, misleading.

Review of popular models and prices

Manufacturers produce various types of heating units designed for a certain power, as a result of which there are some restrictions on the size of the heated area. A review of popular models and prices of solid fuel equipment allows you to determine which product is best installed in a private home.

Candle 18 AREMIKAS

The fuel for this unit is peat briquettes or sawdust. This device uses a special combustion method, in which only 10–20 cm of the bottom layer of the load is burned. The resulting smoke, with the help of a distributor, directs hot air into the combustion chamber.

When choosing any boiler operating mode, the efficiency will always be high. Thanks to the unique design of the equipment, you can save fuel even in winter.

Advantages of the Candle 18 AREMIKAS boiler:

1. Stable and optimal operating mode. Minimum - 7 hours, maximum - 34 hours.
2. Adjusting the water temperature using the air draft regulator.
3. Only a 10–20 cm layer of solid fuel burns, so when the water circulation in the circuit is turned off, its temperature will increase by only 12–16 ºС.
4. Ash removal is carried out 2-3 times a month, as it does not interfere with the combustion process.
5. Compact size.

On the Russian market, the cost of this unit ranges from 54 to 95 thousand rubles and depends on the characteristics of the model.

Prices for solid fuel boilers AREMIKAS

solid fuel boilers AREMIKAS

Zota Mix 40

To operate the domestically produced Zota Mix 40 model, coal and wood are used as the main type of fuel, and gas and liquid serve as backup sources. To change the type of power source for a pellet boiler, remove the ash pan door, and for a gas boiler, open the combustion chamber flap and install the burner. The unit can also operate using electricity. It is possible to install heating elements made of stainless steel.

The water jacket is located along the entire contour of the boiler, including under the ash pan. The design allows the bunker to be cooled and not subject to deformation, provides additional heat removal and improves liquid circulation.

Achieving maximum efficiency is facilitated by the boiler’s ability to maintain an operating pressure of 3 atm, which also guarantees safe operation of the heating system. The level can be increased to 4 atm. for a short time. The unit is equipped with a pressure gauge for monitoring water temperature and pressure, as well as an automatic draft regulator.

Main characteristics:

1. Capable of heating an area of ​​up to 400 m2.
2. Boiler power - 40 kW.
3. The fuel used is solid.
4. By type of installation - floor-mounted.
5. The minimum service life is 15 years.
6. The firebox body is steel.
7. The average price is from 45 to 48 thousand rubles.

Technical characteristics of ZOTA MIX:

Prices for solid fuel boilers ZOTA

solid fuel boilers ZOTA

Alpine Air Solidplus-4

This model is completely independent of electricity. The boiler can be installed in private houses and cottages, which are located in places where there are no power lines. The service life of this unit is over 15 years.

Pros and main features of ALPINE AIR Solidplus-4:

1. Supplied ready-assembled with a warranty.
2. There is a built-in thermostat.
3. Mechanical control.
4. High heat transfer efficiency.
5. Durability of structural elements.
6. Protection against freezing and overheating is provided.
7. Compact sizes.
8. Temperature control.
9. High efficiency. Minimum amount of harmful emissions.
10. Smooth power control.
11. Low heat losses.
12. It works on the principle of three-pass circulation.
13. The chamber material is high-quality cast iron.
14. Will last almost 50 years with proper use.
15. Universal design.
16. Resistance to corrosion process.
17. Economical work.
18. Easy to maintain and manage.

There are models on sale that are characterized by different power, volume of combustion chambers and number of sections, so it is always possible to choose the best option for a private home.

Characteristics:

1. Brand country: Türkiye.
2. Installation type: floor-standing.
3. The power when using firewood will be 25.5 kW, coal - 17 kW.
4. Open combustion chamber. Number of sections - 4.
5. Cast iron heat exchanger.
6. Dimensions: 107 x 52 x 47 cm.
7. Warranty period: 3 years.
8. Price: 45,150 rub.

How to make efficiency high

There are many methods for increasing the efficiency of solid fuel equipment. Each of them helps to increase this parameter from 3 to 7%.

The most effective ways:

1. Using quality fuel. If possible, it is necessary to use only dry and high-quality raw materials for heating the room.
2. Regular removal of ash. If it is not possible to purchase expensive, high-quality fuel, it is necessary to clean the chimney more often.
3. Ventilation of the room. Since the combustion process occurs in the middle part of the unit, it is necessary to ensure a stable flow of fresh air into the room where the equipment will be located.
4. Reducing heat loss. If a residential building gives off heat faster than it heats up, purchasing higher quality fuel or even new boiler equipment will not give the desired result. Therefore, it is necessary to insulate the living space, install new windows made of wood or plastic, and reliable doors.
5. Installation of auxiliary devices. To heat the house evenly, you need to use a circulation pump. This method is very effective and helps increase efficiency. If the old unit does not cope with the task of heating the house, then you can purchase an inexpensive boiler and install it in a cascade. Additional equipment can be used when the old one alone cannot cope with the heating task. You can find out Vilo pumps for heating at the link.