The term "condensing boiler" is for many synonymous with reliable and economical heating equipment. However, not everyone can explain what this concept means, and how a condensing type unit differs from a conventional gas boiler.
Principle of operation and internal structure
In traditional gas heating units, flue gases, the temperature of which is +100-(+170 0 C), together with the formed water vapor, are removed into the atmosphere. The calorific value of the fuel used in such installations is called the net calorific value. Condensing gas boilers, thanks to the use in their design and production the latest technologies, are capable of converting the energy of condensation of water vapor into heat.
Definition! The total energy of combustion of a gaseous fuel, including the energy of converting water vapor into a liquid, is called the gross calorific value of the fuel.
Features of condensing device heat exchangers
Almost every gas boiler can theoretically be made condensing by retrofitting it with a condenser / heat exchanger and ensuring that additional aerodynamic resistance is overcome by the removal of combustion products.
Attention! The surface temperature of the condensing heat exchanger must be below the dew point of the fuel used.
At the beginning of the development of condensing technologies, the production of units of this type followed this path. The operating heat generating plants, as a rule, were floor units made of cast iron, equipped with lamellar condensing modules made of corrosion-resistant steels.
Relatively recently, unified heating systems began to be created. gas installations, originally designed for operation in condensing mode. The heat exchangers of such units must:
- ensure intensive and efficient removal of steam condensation energy;
- be resistant to condensate, which provokes corrosion processes.
Definition! The condensate of gas boilers is a mixture of carbonic, nitric, sulfuric acids of low concentration.
Gas condensing boiler is manufactured with one or two heat exchangers:
- In the first case, this is a double heat exchanger with a branched heat exchange surface, made of stainless steels.
- In the second case, the high-temperature heat exchanger is made of aluminum-silicon alloys, copper, and stainless steel. As a rule, such a heat exchanger is made of stainless steel.
Attention! Cast iron is not used in wall-mounted boilers for high-temperature heat exchangers due to its significant mass.
Advantages of condensing gas heating equipment
- The innovative design of the burners ensures almost complete combustion of fuel, due to the high efficiency, the amount of gas used is reduced (by 10-15%) and, consequently, the amount of emissions into the atmosphere is reduced.
Attention! The maximum efficiency is obtained when using units of this type in low temperature heating e.g. in underfloor heating systems.
- equipment thanks to design features, is virtually silent.
- Wall-mounted models can have a power of up to 100 kW, while traditional wall-mounted gas boilers produce a maximum power of 35 kW.
- The service life of this heating equipment is 2-3 times higher than that of conventional gas units.
Manufacturers of heating equipment of the type in question
To the condenser heating technology of the highest class can be attributed to the products of the German companies Viessmann and Buderus, the Italian company Baxi.
- Condensing gas boilers Viessmann Vitodens have a power range from 4 to 66 kW. These units are manufactured using a fundamentally new design of the heating surface. The Inox-Radial heat exchanger is a parallelepiped coiled into a coil. Stainless steel is used for its production. The company completely abandoned the installation of aluminum heat exchangers due to lower corrosion resistance and, consequently, a shorter service life.
Attention! The design of Inox-Radial heat exchangers provides for the possibility of installing, if necessary, devices for condensate neutralization.
Vitodens 300, 333, 343 are equipped with modulating burners to save fuel and modulating circulation pumps to minimize energy consumption. The cost of installations with a capacity of 26 kW is approximately $ 1,800.
- The German company Buderus is a pioneer in the production of condensing technology. Logamax plus GB 112 models are manufactured with a capacity of 80 and 100 kW, which is a record for wall-mounted gas boilers. At the same time, the units have compact dimensions - their width is equal to that of conventional boilers with a capacity of 24 kW. This equipment uses a finned heat exchanger made of silicon-aluminum alloys. approximate price boilers of this brand with a capacity of 24 kW - $ 1,400.
Models of the BAXI brand are a combination of excellent performance characteristics and reasonable price. The 28kW Prime HT costs approximately $1,500. This economy class condensing wall-mounted boiler is equipped with the possibility of electronic modulation of the flame, both in heating and cooking mode. hot water.
In the production of heating systems, the most promising innovative technology is the condensation of water vapor, which is formed during the combustion of hydrocarbons. This is how condensing boilers work. This new heating equipment has appeared on the Russian market recently, but is already in considerable consumer demand. Condensing boilers of both foreign and domestic manufacturers are on sale.
A wide range of condensing boilers is offered by BAXI, which, thanks to high quality its products, has become a leader Russian market boiler equipment. Condensing boilers Baksi are floor and wall-mounted condensing boilers, characterized by a high efficiency. Other well-known brands of boiler equipment in the domestic market include condensing vaillant boilers and wisman.
condensing boiler
Principles of combustion and condensation
Any hydrocarbon fuel releases heat when burned. In the process of fuel combustion, the end products are carbon dioxide (CO 2) and (H 2 O) water, which, under the influence of high temperatures, turns into steam. When evaporating, water expends heat, but it can be obtained back in the process of condensation, that is, if the water from the gaseous phase passes back into the liquid.
How condensing boilers work
The principle of operation of condensing boilers has been known for a long time, but it was impossible to use it in boiler equipment made of cast iron and steel, since water condensate, having high acidity and containing carbon dioxide, caused corrosion of steel and cast iron boilers. Only with the advent of corrosion-resistant alloys and stainless steel, it became possible to introduce this technology in the production of boiler equipment.
As we already know, when cooled, the vapor again turns into a liquid state and releases a certain amount of heat. If we consider a conventional boiler, then during its operation there is a struggle with the condensation process, and in condensing boilers, condensation is only welcome. Their design provides for a special heat exchanger, in which the condensation process takes place, and the heat generated during this process is taken for the heating system.
The condensing boiler has an efficiency of 108-109%. How is this possible if, according to the laws of physics, the efficiency cannot exceed 100%, since energy losses in any processes are inevitable.
In non-condensing boilers, not all heat energy is taken away during gas combustion, but only its most of. The heat flow in the heat exchanger is cooled only to a temperature of 140-160 ° C, when it is cooled to a lower temperature, the draft decreases in the chimney, aggressive condensate is formed, causing corrosion of the boiler elements. Thermal energy, which can be obtained during the condensation process in conventional boilers is not used, it is called latent.
Condensing gas boilers use in their work the energy hidden in condensing water vapor, therefore their efficiency, in comparison with the efficiency of conventional boilers, exceeds 100%. The main element of any boiler is a heat exchanger. There are two heat exchangers in the design of condensing boilers. They can be separate or combined (two-stage). The first heat exchanger works in the same way as in conventional boilers. A heat flow passes through it, but does not cool below the dew point. The second condensing heat exchanger removes the heat remaining from the combustion products and cools it down to a temperature below the dew point.
Water vapor condenses on the walls of the second heat exchanger and releases latent heat energy to water. At this moment, additional heat is taken from the combustion products; their temperature at the exit from the heat exchanger is only 10-15°C higher than the coolant temperature.
To solve the problem of corrosion caused by aggressive condensate, manufacturers use materials that are resistant to corrosion and chemical attack (stainless steel, silumin (aluminum-silicon alloy)) in the manufacture of boilers.
In Europe, and in particular in Germany, there are regulations requiring that condensate be neutralized before being discharged into the sewer. The neutralizer is a container with granules of magnesium and potassium. By passing through these alkaline reagents, the condensate is neutralized, and when discharged into the sewer, it does not pose a danger to environment. In Russia sanitary norms do not require condensate neutralization, so it is simply collected in a special tank provided in the boiler design, and, as a result, is discharged into the sewer in its original form. In boilers with a capacity of up to 30 kW, intended for heating private houses, about 30 liters of condensate are formed in 24 hours a day.
Advantages and disadvantages of condensing boilers
Wall mounted heating boiler
A condensing gas boiler can be called one of the most economical and highly efficient heating appliances. Its efficiency is 10-15% higher than the efficiency of a traditional boiler. In addition, condensing boilers are 20% more economical than conventional boiler equipment.
The design of condensing boilers uses high-tech burners that prepare fuel-air mixtures in optimal proportions, which minimizes the possibility of incomplete combustion of the fuel. This reduces emissions harmful substances.
Exhaust gases have a low temperature (below 40 °C), which makes it possible to use plastic chimneys for condensing boilers, thereby reducing installation costs heating system.
The advantages of condensing boilers include:
- small dimensions and light weight of boiler equipment;
- efficiency (gas savings are 35% per season);
- deep modulation (saving gas at partial loads);
- low vibration and low noise;
- possibility of cascade installation;
- savings on the chimney (you can install chimneys with a smaller diameter);
- reduction of emissions of harmful substances NO X and CO 2 (7 times lower than conventional boilers).
Cascade of condensing boilers
Due to the small dimensions and low weight of the boiler equipment, the installation of the boiler requires less space at the same time, the cost of its transportation and installation is reduced. There is a misconception that condensing boilers work effectively only with underfloor heating systems. In another case, their efficiency is no more than that of traditional boilers. But it's not. In construction condensing boiler there is a modulating burner that allows you to achieve deep modulation of power, while reducing the cost of gas and air.
The process of condensation in the boiler also occurs during the operation of heating equipment with a radiator heating system. At reduced loads, the efficiency of a condensing boiler may well reach high values, unlike conventional gas boilers, in which the efficiency drops in this mode due to an excess of air.
For the cascade installation of condensing boilers, manufacturers offer special regulators (for example, BAXI sells the RVA47 regulator for its boilers), which turn boilers installed separately into a single system.
The advantages of the cascade system are the ease of installation and the compact dimensions of the boiler room. Due to the reduced vibrations and low noise level during the installation of condensing boilers, there is no need to make vibration-proof platforms and soundproof the room intended for the boiler room. Which also saves cash when installing a heating system.
To save on the size of the chimney, the fan working in condensing boilers allows. He develops quite high pressure, so the diameter of the chimney can be two times smaller than when installing a heating system with traditional boilers.
Due to low NO X and CO 2 emissions, condensing boilers are classified as environmentally friendly equipment, they are often used to equip boiler houses in resort and protected areas. Finding flaws in condensing boilers is very difficult. The main disadvantage of this heating equipment is high price, which is twice the price of conventional boilers.
Application
By appearance condensing boilers are not much different from traditional ones. They are made in wall version and outdoor version. Wall-mounted gas condensing boilers have less power than floor standing ones and are used in everyday life for heating private houses and cottages.
Floorstanding condensing boilers with high output are used for heating industrial facilities and office space.
Condensing gas boilers produce single and double circuit. Double-circuit boilers are used for both heating and water heating. The power of single- and double-circuit boilers is 20-100 kW. This is enough for domestic use boilers. For industrial applications produce models with higher power.
The main differences between the design of condensing boilers and conventional boilers
Condensing boilers differ from traditional material used for the heat exchanger. Their heat exchanger is made of acid-resistant silumin alloy or stainless steel. The water condensate formed in the boiler has hyperacidity and causes corrosion of materials such as steel and cast iron, which are used in the manufacture of non-condensing boilers. The shape of the heat exchanger is a pipe of complex cross section with additional helical ribs. This form of heat exchanger increases the heat exchange area and increases the efficiency of the boiler.
In condensing boilers, a fan is installed in front of the burner, which “sucks” the gas from the gas pipeline and mixes it with air, after which it directs the mixture of gas and air to the burner.
Condensing boiler device
Flue gases are removed through coaxial chimneys made of heat-resistant plastic. In addition, the condensing boilers have an electronically controlled pump that optimizes the heating output, saving energy and reducing noise from the heating medium flowing in the heating system.
The design of traditional boilers does not provide for the condensation process and the use of indoor energy, so the temperature of the combustion products is maintained at a high level. Part of the heat in such boilers is not used, but is removed with combustion products through the chimney.
Since condensate is chemically aggressive, in order to use it, it is necessary to make boiler elements from chemically sustainable materials, which are quite expensive. It is much easier for manufacturers to sell cheaper products than to invest in advanced but expensive technologies. Therefore, most of the boilers on the market are based on outdated technologies. For users, it is more profitable to buy albeit expensive, but more efficient condensing boilers that save on fuel consumption.
Manufacturers offer connection kits, condensate neutralizers, expansion tanks, safety devices, boiler piping kits, flue gas exhaust systems.
In European countries, condensing boilers are the most popular type of heating appliances. There are countries where the installation of non-condensing boilers is prohibited. The reason for this is more high efficiency D and lower emission of harmful substances in condensing boilers.
The complexity of applying the principle of condensation used to be that the accumulated condensate in the gas heating boiler led to corrosion metal elements designs. The problem ceased to exist when corrosion-resistant alloys and stainless steel began to be used for the manufacture of equipment.
Boiler device
Condensing boiler - what is it in terms of design?
The main working element is a stainless steel heat exchanger in the form of a coil. Inside the spiral is heating element(burner). The coolant enters the coil from the return, heated by the burner.
From the side of the inlet pipe, where the water is the coldest (less than 59 degrees), steam condenses on the walls of the chamber. In condensing models, the combustion chamber closed type, i.e. The boiler takes the combustion air from the street, and the combustion products do not leak into the boiler room.
The system is equipped with:
- a circulation pump that forcibly distills the coolant (located on the return pipe, equipped with a filter);
- coaxial chimney (double pipe, for air supply and smoke removal at the same time), connected at the top of the unit;
- fan for forced air supply to the burner;
- steam trap.
The circuit includes protection and control devices (). Modern models boilers allow the possibility remote control, starting with remotes and ending with SMS.
Pros and cons
Conventional or condensing boiler - which is better, and in what situations?
The main advantages of condensing units are high efficiency and economy. Due to the design of the burner (), the fuel burns out almost completely, the amount of waste is minimal - that is, in environmentally this boiler is better too.
The smoke temperature is below 40 degrees - this means that plastic chimneys can be used, and they are cheaper than metal ones. Due to the smaller amount of combustion products and built-in forced ventilation smaller pipes can be used.
The advantages of this boiler equipment include:
- compactness, light weight;
- easier installation;
- modulating burner;
- gas savings, an average of 35%;
- low level of noise and vibrations;
- savings on the chimney;
- environmental friendliness (7 times less harmful emissions);
- cascade installation is possible (several boilers in a common system).
The main disadvantage is the high price, but in a properly organized heating system, the difference pays off.
Features of condensation models
The principle of operation of condensing boilers is such that a small temperature fork between supply and return is needed for operation. Means, initial temperature coolant should not be too high. Therefore, it is believed that the most effective use of such models is.
Like a simple gas boiler, a condensing boiler exists in design. The advantage of the floor - higher power, wall - compactness. The power of the unit is selected at the rate of 1 kilowatt per 10 square meters plus 10% of the reserve.
For small house a high power boiler is not needed. A compact and eco-friendly wall model can be hung in the kitchen, no separate boiler room is required.
Video about the principle of operation of a condensing boiler.
The condensing boiler is actively used in all European countries. No one doubts that this is a practical and reliable device. Europeans simply admire it - it is environmentally friendly equipment and significant energy savings. The first country to start using a condensing boiler was Holland. In the United States, the use of such devices makes it possible to obtain preferential terms taxation. Per last years the technology of their production has become much cheaper, which allows you to pay attention to them all more of people. However, these units are twice as expensive as conventional ones, which is quite justified.
A condensing boiler works on a very simple principle. The creation of such devices became possible only after the appearance of a corrosion-resistant light alloy made of stainless steel. This is due to the fact that in the process of formation of water condensate, corrosion of cast iron and steel occurred. Now we can talk about how a gas condensing boiler works. Water enters the unit, heating up there due to the combustion of gas. After that, it is sent from the boiler to the heating system, where it cools down. Further, the water is again in the boiler. When the gas burns, not only heat is formed, but also various products of this process in the form of chemical compounds. The combustion of hydrocarbon fuels produces water and nitrogen. The first component turns into steam under the influence of high temperatures. Incomplete combustion of fuel leads to the formation of carbon monoxide and soot. These hot gases give off their energy to the heat carrier, passing through the boiler heat exchanger, and water is heated. The cooled gases exit to the atmosphere through the chimney. goes away with the smoke.
The condensing boiler is equipped with a specially designed secondary heat exchanger, which allows water to condense on surfaces where the temperature is less than 50°C. The heating system return heat carrier is used to settle the steam. Warm gas, which was not used in the process of heating water in the main heat exchanger, ends up in the second one, where the liquid flows after cooling. The vapors condense, giving off some of the energy, which makes it possible to heat the water. The resulting condensate drain pipe goes down the drain.
Gas condensing units work the more efficiently, the lower the temperature of the water entering the device. The optimum temperature for such devices is 30-40 degrees Celsius. In a radiator system, the temperature is usually 60-70 degrees, which leads to a decrease in the efficiency of such equipment, but it still remains quite high. Optimum performance condensing boiler is possible when the difference in the temperature of the direct and return lines is at the level of 20 degrees, no more.
The gas condensing boiler is a relatively new concept in the field of heating technology. Distinctive feature equipment is a high efficiency, especially at low temperatures. The units were created with the aim of saving energy, improving efficiency and improving environmental performance. The most famous companies: Vaillant, Baxi, Viessman, Ariston, Bosh manufacture boilers according to innovative technologies that meets all standards.
To understand what a condensing gas boiler is and how it works, you need to understand how it works. In conventional heating units, combustion products are removed into the atmosphere at a temperature of 100-170 ° C with water vapor, reducing efficiency. Thermal energy, designed to increase the efficiency of the carrier, flies out through the chimney along with waste.
The principle of operation of a condensing boiler is the reverse exchange process, in which latent heat is taken from the exhaust air and transferred to the room. The recovery efficiency factor is the ratio between the maximum possible energy received and its actual value. Depending on the power of the unit, the indicator can reach 90% efficiency. Smoke emission in such condensing products is carried out through coaxial chimney. Automation allows you to select right conditions for a fan that blows air at a variable speed.
The device for heating differs from similar standard types in that the boiler is equipped with an additional heat exchanger (separate or combined), which receives the carrier in the reverse direction from the circuit. Condensation depends on the pressure, type of fuel, oxygen and gas concentration. When a dew point is formed on the body of a gas boiler, the carrier is heated, so it enters the base with more high temperature. The necessary energy is created in a short time and with low resource costs.
To prevent negative impact water vapor exchangers are made of stainless steel or silumin. Also, the specificity lies in the features of the burner, which provides optimal ratio gas and air, constantly monitoring the process in the condensing unit. The closed combustion chamber is isolated from the room, which guarantees the safe operation of heating equipment.
Description of models
Well-known manufacturers of heating equipment offer wall and floor standing boilers, with one- and two-pipe wiring. Like any device, these devices have their pros and cons. To have an idea about the proposed condensing gas boilers, you can consider the products of several companies:
The devices are designed for use in multi-apartment and private houses, for industrial facilities. The Vitosolar-300F is a compact 800 l solar heater unit. Also included are expansion tank, pump, pipelines, mixers, condensing gas boiler. All elements are mounted in a single block, which ensures convenience and ease of installation. Burner and radial heat exchanger made of stainless steel. Using built-in electronics, the operation is controlled in a given mode, depending on the air temperature in the room.
Viessman Vitodens-300V – wall model with 98% efficiency, MatriX burner, diagnostic unit. The gas boiler unit collects data from sensors, measures the speed of the carrier and transmits the information received to the switch, which is triggered when energy consumption is reduced. Thanks to the Smart system, the risk of breakage is reduced to zero.
A distinctive feature of the condensing units of this company is high performance combined with compact dimensions and low weight. According to the heating method, there are single and double circuit systems with natural and forced methods. The Pro series includes Atmo TEC pro VUW equipment. Available in standard and reduced versions, power - up to 24 kW. Equipped closed camera combustion and turbocharged smoke extraction.
The Vaillant TEC plus VUW single-circuit device with natural smoke extraction provides high-quality heating and makes it possible to connect a water heater. Automation allows you to control processes and set the temperature. With the help of a valve with a built-in stepper motor, wall-mounted gas heating boilers smoothly reach required level power.
Judging by consumer reviews, the condensing boilers of this company are especially effective in homes without a centralized water supply. All types can work on liquefied gas, the temperature is adjusted in two modes: 30-85°C and 30-45°C for underfloor heating. The Baxi ECO Compact electric gas boiler is adapted to any fuel, equipped with auto ignition, a modulating burner and ionization flame control. The exhaust gases pass open chamber combustion.
DUO-TEC is a two-circuit heating device with the possibility of connecting an external storage boiler. It has a control panel with an accessible display, built-in automation that responds to the climate. The condensing gas boiler provides control over multi-temperature zone systems.
Each model can connect to solar collectors, equipped with a high-speed plate exchanger for efficient heating. The supply and mixing system gives the optimum ratio of gas and air. The burner is designed for 25 years of service. The GAZ 2000 brand has a membrane expansion tank, circulation pump with deaerator and three speeds.
The gas boiler Condens 2000 W ZWB can operate at a pressure of 5 bar, according to customer reviews, adapted for apartment buildings and private houses. The fuel used is natural or liquefied gas with a maximum flow rate of 2.5 m3/h. The hot water output is 12 l/min.
Buyer opinions
Based on consumer opinions about different models and the principle of operation of gas boilers, taking into account all the pros and cons, you can make a choice of suitable equipment for heating a house and hot water supply:
“I installed a solar system in my house in order to save money, I needed to buy the appropriate equipment for heating. The most suitable technique for me is the condensation type. Atmo TEC pro VUW from the German manufacturer Vaillant has been working for two years without interruption. Provides not only all rooms, perfectly combined with warm floors. The electronics are sensors and a screen with an accessible interface that controls all modes according to the specified functions.
Viktor, Moscow.
“Condensing boilers are quite comfortable and functional. But for savings, it is important that the temperature of the coolant is a maximum of 60 ° C. In our house with an area of 300 m2, a double-circuit Vitosolar-300F is installed, which is manufactured by Viessman. On particularly cold days, the radiators were quite hot, the flow did not exceed 50°C. At the same time, gas consumption was about 1,000 m3 per month. We noticed that for such devices it is necessary to use clean water. A competent approach to operation ensures uninterrupted operation and a long service life.
Vadim, St. Petersburg.
“They planned to buy a condensing gas boiler at the design stage of the house. The question was only about the manufacturer. We trusted the Italian company Baxi and chose the ECO Compact model. Works well for heating low temperatures also provides hot water. The automation system is convenient: you set the mode - and you don’t have to worry. Impressed by the aesthetic design. Many friends have similar equipment, the reviews are the most positive. Even in severe frost, the house is warm.”
Anna, Kyiv.
“When we decided to purchase a new boiler, the question of savings arose. I wanted to choose a device that meets all the requirements. After reviewing several options and re-reading a lot of reviews, we settled on the German company Bosh. They have a huge model line of condensing appliances with different capacities and capabilities. GAZ 2000, which we installed three years ago, showed itself only with better side. Convenient automatic control, beautiful decoration, quality service. We plan to install in a year solar system, since this brand is perfect for her. Savings will increase several times, so the rather high price fully justifies itself.”
Maria, Kharkov.
Summary
Summing up, we can note the pros and cons of such boilers for heating:
1. Low noise and vibration.
2. High efficiency.
3. Improving the emission of combustion products by half.
4. Reducing the release of harmful substances into space.
5. Compact size and light weight.
6. Fuel economy is increased by 30%.
7. Possibility of installing solar systems.
Like any equipment, gas condensing boilers have disadvantages:
- Pretty high price.
- The work involves the loss of condensate, so it is necessary to think over a system for removing its excess.
- Possibility of operation only in low temperature mode.
- Energy dependence.
Price overview
The cost of condensing products from different manufacturers is formed on the basis of power and specifications. The table shows the models of the most famous brands and their prices:
| Manufacturer, model | Boiler installation option | Number of circuits | Dimensions (h/w/d in mm) | Weight, kg | Power, kWt) | efficiency % | Cost, rubles |
| Viessmann, Germany | Wall | 2 | 850x450x360 | 120 | 35 | 110 | 90 000 |
| Vaillant, Germany-Slovakia Atmo TEC pro VUW |
Wall | 2 | 440x720x338 | 35 | 24 | 107 | 60 000 |
| Baxi, Italy | Wall | 1 | 700x400x298 | 30 | 24 | 90 | 50 000 |
| Bosch, Germany Condens 2000W ZWB |
Wall | 2 | 700x400x300 | 40 | 25 | 103 | 80 000 |
Wall-mounted condensing boilers are highly efficient, economical equipment that can be installed both for new heating elements and for existing ones.
Loading...