Condensing heating boilers are an innovative development that is successfully used in EU countries. Due to the increased efficiency, the device allows you to save on heating, which is very important in our time. In this article I will talk about its structure and features.

Condensing boilers

Operating principle

Condensing gas boilers are a type of heating equipment designed to heat the heating system and sanitary water (in the case of a double-circuit design).

Like conventional boilers, it has:

• gas combustion chamber;
• heat exchangers;
• expansion tank;
• coaxial chimney;
• control automation;
• circulation pump.

However, there are also significant differences.

The principle of operation of the device is based on the fact that when the heat of the burnt fuel is released, condensation occurs of vapors formed from water in natural gas. As a result, the vaporization energy hidden in these vapors is not released through the chimney into the street, but is used for additional heating of the coolant.

As is known, dew point temperature is required for water to condense. Under gas boiler conditions it is equal to 57 °C. Therefore, for the system to operate, the heat exchanger or part of it must be cooled below the dew point temperature.

To do this, the temperature of the return coolant supply must be 40 - 50 °C or lower. This means that a condensing boiler will work productively only with a low-temperature, high-inertia heating system. This could be underfloor heating or panel heating.

Another condition for the effective operation of the device is presence of special a heat exchanger that can sufficiently cool the combustion products of fuel. First, these products pass through the part of the heat exchanger farthest from the return, they are pre-cooled, then they again pass through the coldest and closest to the return part of the economizer and are cooled below 57 ° C.

Water vapor contained in combustion products condenses on the walls of the heat exchanger and releases thermal energy released during condensation. This is, at first glance, an insignificant amount of heat can increase boiler efficiency by 9 - 11% compared to a conventional convection device.

So, we have a boiler that receives additional heat by cooling the gas combustion products. As a result Steam condenses on the walls of the heat exchanger, and the released energy is used to heat the coolant.

Device

In general, the design of a condensing unit resembles the design of a conventional gas boiler.

To implement the principle described above, the following nodes must be present:

• A special heat exchanger made of corrosion-resistant material (copper or silumin), which is divided into two sections. In one of the sections, the main heating of the coolant occurs, then the combustion products are sent to an additional section with the coldest water, where the water vapor condenses and releases its energy;
• A closed combustion chamber with a coaxial chimney allows more precise control of the process of movement of gas combustion products and the saturation of the mixture with oxygen;
• A blower fan in front of the heat exchanger with a variable speed allows maintaining an optimal air/natural gas ratio;
• Chimney made of ceramics or heat-resistant plastic. It is possible to use plastic here, since the smoke temperature does not exceed 70 °C;
• Flue gas removal pump with electronic power control. It optimizes the operation of the device, reduces noise and helps set the optimal mode;
• Condensate removal system. The water settled on the walls of the heat exchanger is discharged into the sewer.

The photo shows a plastic coaxial chimney.

For the most productive and comfortable operation of the device, it is necessary to have a low-temperature heating system, for example, “

You can set up the device yourself, but it is better to call a specialist.

Among the advantages of using condensate units, the following features are usually distinguished:

1. The most efficient use of thermal energy from fuel combustion;
2. The highest efficiency of all known heating boilers;
3. Simple instructions for using the device;
4. Significant savings on energy costs;
5. Reliable and durable performance.

It is important to understand that this is not an innovation in its infancy. The devices are successfully used in many European countries, and their residents have not asked what it is for a long time. In some countries, for example, in the UK, only condensing boilers are sold, as the government cares about savings and the general well-being of citizens.

The only drawback is the high price of the device, but it quickly pays for itself due to gas savings, which is very expensive in European countries. Considering that the problem of the high cost of energy resources is gradually becoming relevant for everyone, Russian citizens should also take a closer look at this technology.

Conclusion

We looked at a condensing boiler and examined the principle of its operation. This device allows you to achieve maximum efficiency and significant savings on heating. You can get even more information from the video in this article, and ask your questions in the comments.

Due to their design features and operating principle, condensing boilers use fuel energy much more efficiently and economically than traditional gas units. Despite the fact that the price of condensing equipment is still high, homeowners are increasingly choosing it. And this is not surprising - the boiler efficiency reaches up to 98%, and gas savings reach 20%. Experts say that condensation technology is the future.

Operating principle of condensing boilers

The cost of fuel is becoming higher from year to year, so energy-saving technologies are confidently gaining popularity. Condensing boilers appeared in the middle of the last century, but they were not immediately able to win the trust of consumers. At that time, the devices were unreliable, and manufacturers had to modify their design. As a result, they ensured that these models of heating boilers took leading positions in the market.

An interesting fact is that European countries stimulate and support their citizens who decide to buy a condensing gas boiler by providing loans at minimal interest.

A conventional heating boiler running on natural gas uses only part of the energy obtained from combustion of fuel. Exhaust gases, which have a fairly high temperature and powerful potential, are discharged into the atmosphere through the chimney, giving off unused heat to the outside air. A condensing gas unit more efficiently uses thermal resources released not only during gas combustion, but also during condensation of water vapor contained in smoke. The steam entering a separate heat exchanger, when cooled, turns into a liquid called condensate. This releases a certain amount of heat. Moisture is discharged into the condensate collector, and thermal energy is discharged into the heating system.

A conventional gas boiler uses a lower calorific value during operation, while condensing-type equipment uses a higher calorific value, consisting of the heat released during fuel combustion and the heat generated during condensation. This is the more efficient use of natural gas and efficiency, as well as increased efficiency indicators, which distinguish not only floor-standing units, but also wall-mounted heating devices.

The condensation-type equipment under consideration is ideal for radiator heating and hot water supply systems, as well as for underfloor heating.

Design of condensing heating devices

Any of the boilers has a heat exchanger in which the coolant is heated, which then enters the heating system of the house through pipework. Gas boilers of the condensing operating principle are equipped with two heat exchangers, the first of which operates according to the traditional scheme, and the second, condensing, is put into operation later.

The secondary heat exchanger is a structure of pipes of complex cross-section with spiral fins. This shape allows you to significantly increase the area in contact with steam. Flue gases in an additional heat exchanger heat the coolant coming from the return line. At this point, the water vapor cools to its dew point, resulting in condensation.

In other words, in a condensing boiler, part of the energy is returned for reuse, whereas during the operation of a conventional boiler it is irretrievably evaporated into the atmosphere along with steam.

For the manufacture of secondary heat exchangers, stainless steel is used, as well as coatings made of aluminum-silicon alloys called silumin. This protects the device from chemically aggressive condensate.

Gas condensing boilers are equipped with high-tech burners. Their peculiarity is that in combustion mode they provide constant control over the mixing proportions of the gas-air mixture, maintaining the optimal ratio. The design of heating devices has a closed combustion chamber, isolated from the room. Therefore, the boilers in question are relatively safe equipment.

Externally, energy-saving and traditional gas boilers are practically no different. Manufacturers produce wall-mounted and floor-mounted models, in single-circuit and multi-circuit versions. But you should pay attention to the fact that condensing equipment has more power with the same dimensions. For example, wall-mounted boilers that use the heat of air steam can have a power of up to 110 kW, while conventional gas units with a power of more than 40 kW are available in a floor-standing version.

Modern models of heating boilers using the condensing principle of operation are available in two modifications - with dry or wet heat transfer. The first option is intended for residential buildings, and the second, more efficient and expensive, for boiler houses. But boilers with wet heat transfer have not yet been fully developed, because... are still under development.

Condensate disposal

A condensing boiler produces a fairly large volume of condensate per day. It depends on the power of the equipment and can be 30 or more liters. It is not allowed to pour aggressive liquids directly into the household sewer system, which is why manufacturers equip modern gas heating appliances with neutralizers.

The additional device is a separate tank into which acid condensate enters. It passes through a layer of alkali metals (magnesium and potassium), resulting in a chemical reaction. As a result, the condensate decomposes into carbon dioxide and water, which can already be drained into the sewer system.

How profitable is it to use condensing boilers?

There are many opinions about the economic benefits of using condensing gas equipment in domestic conditions. The fact is that for consumers in Russia the price of gas is significantly lower than for residents of European countries. Therefore, some experts claim that condensing boilers in our conditions will pay for themselves in at least ten years. But this is not true.

Firstly, gas is not as cheap as we would like. Secondly, reviews from owners of heating boilers indicate that significant savings can be visible already in 2-4 years of operation. This period depends on the technical characteristics of the equipment, such as power, and on additional equipment.

For clarity, we should consider some examples.

A budget option

A condensing boiler with a built-in heat exchanger for a private house, involving a heat load of up to 30 kW with the simplest wiring and connecting only heating radiators, will cost a third more than a traditional boiler. But operating costs at maximum loads will make it possible to return this difference in 3.5-4 years, taking into account the annual increase in gas prices. In the future, the condensing boiler will begin to significantly save fuel costs, becoming more profitable every year.

Advanced option

The price of a traditional boiler (including the purchase of a set of additional devices) for a house requiring a heat load of approximately 35 kW, with a multi-circuit heating distribution system and the presence of a 200-liter hot water tank will be higher than condensing gas equipment. Therefore, there is no need to talk about payback here. It turns out that a condensing boiler, designed for medium heat loads, begins to save the owner’s money from the first day.

Highly advanced option

In this category, you can consider multi-circuit boilers with a heat load reaching 60 kW. In this case, the condensing boiler will need to be completed, so its price will be 15-20% higher. But the difference, taking into account the rise in gas prices, will be equal sooner than with the budget option. We can talk about payback in 2.5-3 years.

Reviews from experts and consumers indicate that condensing heating boilers are preferred by those owners who know how to count their money. They understand that in addition to saving on gas bills, such equipment will last at least twice as long compared to a conventional gas appliance.

But do not forget that the efficiency of condensing equipment will depend on several factors:

• boiler age;
• correct ratio of heated volume and power characteristics of the unit;
• use of modern gas burners.

Installation of floor-standing gas boilers

High-power boilers are manufactured in floor-mounted versions. They are installed in separate rooms in which it is possible to organize additional ventilation. The installation process is carried out in stages.

1. At the stage of preparatory work, a foundation is installed in the form of a concrete pad 100-200 mm high or a support frame is installed.
2. The connection points for the chimney, supply and return heating pipes to the boiler equipment are determined and organized.
3. The gas boiler is installed horizontally on the prepared base. It is adjusted using screw feet.
4. The unit is connected to the pipelines of the coolant circulation system. It is taken into account that double-circuit and multi-circuit boilers have additional pipes and flexible piping.

Before entering the heating boiler, a special coarse filter must be installed on the return pipe to prevent scale or rust from entering the heat exchanger.

1. The unit is connected to the gas pipeline using copper pipes or flexible hoses. A valve is mounted on the inlet pipe. The outlet pipe is connected to the chimney.
2. Seams and connections are checked for leaks, and gas pressure in the pipeline is checked for compliance with regulatory requirements.

Regardless of the model, floor-standing gas boilers can be installed in rooms with a ceiling height of at least two meters. One unit requires a minimum volume of space of 7.5 m3 and a mandatory ventilation hole for the flow of air from outside.

The minimum distance from a wall made of non-combustible materials is allowed to be 100mm. Roofing steel with a thickness of at least three millimeters is used as an insulating material.

Non-flammable coverings must be laid on the floor under the gas boiler. It could be:

• steel sheet;
• tile;
• a natural stone;
• cement strainer;
• expanded clay concrete slabs.

Installation of wall-mounted boilers

Wall-mounted devices are installed after preparing the electrical connections and connections to the hydraulic and gas circuits, which is done using the supplied templates. Before this is determined:

• location of the heating device;
• possibility of communication arrangement;
• admissibility of organizing the correct removal of combustion products.

The wall-mounted heating boiler must be secured to a reliable base. In most cases, load-bearing walls or a specially installed frame in the form of frames, consoles, hangers, racks, etc. are used for this. Manufacturers provide a range of fixtures and fittings, supplied complete with equipment or purchased separately. Also, the wall-mounted unit can be fixed to a vertical fence using a mounting frame made for a specific model of heating device. Its use in combination with decorative panels and covers allows the condensation equipment to harmoniously fit into the interior of the room.

After installing the boiler on the wall, they begin to directly connect it to the supplied utility networks and communications.

The pipe responsible for removing carbon monoxide is connected through corrugated pipes to the chimney. In this case, their sharp bends are not allowed. The chimney should not be located at a distance of less than 100mm from flammable surfaces. In any case, it would be better to isolate them.

Valves are installed on gas pipes and gas pipelines are checked for leaks. The wall-mounted boiler must be connected by a specialist, carrying out appropriate tests and purging of the pipes.

To be able to connect the equipment to a 220V power supply, you will need to install an outlet and have a stabilizer. We should not forget about the grounding of condensing boilers, and also that contact of the cable with hot elements can lead to its melting and failure. Safety requirements must be observed unquestioningly.

The water circuit is connected to the wall-mounted boiler following the appropriate diagrams supplied with the equipment.

Features of chimneys for condensing boilers

On wall-mounted and floor-mounted condensing-type boilers, ready-made chimney pipes made of plastic or aluminum are installed. By design they can be:

• coaxial, which is a “pipe-in-pipe” design;
• two-pipe, divided into smoke exhaust and air intake segments.

The low temperature of the exhaust gases exiting through the chimney allows the use of plastic in the exhaust system. At a temperature of 35-70 degrees it does not deform, does not melt and copes with its functions perfectly.

This circumstance greatly helps when replacing an old boiler with a brick chimney with new equipment. A conventional gas boiler will require dismantling the old chimney, since temperature fluctuations and aggressive condensation will cause the masonry to collapse too quickly. To prevent an emergency, you will have to think in advance about installing an anti-corrosion, gas-tight chimney made of stainless steel or polymer liners, the price of which is quite high.

For a condensing boiler, you can limit yourself to lining the old chimney with plastic, which will be much cheaper.

Myths about condensing boilers

The popularity of any product always gives rise to numerous rumors and myths, which do not always reflect reality. Condensing boilers, both wall-mounted and floor-mounted, are no exception. Let's try to understand some of them.

Price

Experts say that condensing boilers are more expensive than traditional gas units. But this is only with a superficial glance at the price tag or price list. Having understood the issue, you can understand that the equipment differs not only in price and design option (wall-mounted or floor-mounted, single- or double-circuit devices), but also in thermal power.

By paying attention to the technical characteristics of gas boilers of different operating principles, as well as comparing two units with the same performance and capabilities, you can be convinced that the final price of traditional equipment is often higher than condensing equipment. And if we take into account that for conventional gas boilers it is necessary to purchase additional devices, the price of which can be significant, then the question of the higher cost of condensing equipment will disappear by itself.

Efficiency

Many manufacturers claim that their condensing boilers have an efficiency of more than 100%. This statement evokes a double feeling. On the one hand, it is quite attractive to consumers, but on the other, it causes confusion.

The use of additional heat, of course, increases the efficiency of using this type of equipment and increases efficiency. But talking about a coefficient exceeding 100% is only conditional.

The fact is that to facilitate the comparison of two types of gas heating equipment, the efficiency is calculated using the method for determining the indicator for traditional boilers that use only the lower calorific value. And here the heat of condensation is not taken into account, which adds 7-9% to the efficiency. Condensing units use 100% of the lower heat and its part arising as a result of the condensation process, which makes up the figure of 107-109%. In fact, the efficiency does not rise above 98%.

Chimney

Despite opinions about the need for condensation devices to install chimneys made of acid-resistant materials, the price of which is quite high, they are not much different from conventional chimneys installed in systems of gas units with a closed firebox.

Spent combustion products are removed forcibly, so the boilers in question can be connected to various smoke exhaust systems. The main thing is to maintain the tightness of the structure.

Condensate

Many consumers are sure that when the boiler operates, problems arise due to the appearance of condensation. But manufacturers of condensing equipment include systems for neutralizing and recycling aggressive moisture into the design of their devices. For conventional gas units, in the chimneys of which condensate is present, although in smaller quantities, diverters and neutralizers are installed additionally.

Famous manufacturers

The heating equipment market is diverse and extensive. Domestic and foreign manufacturers offer a huge range of boilers, differing in their dimensions, power and type of fuel used. Among the most well-known manufacturers of condensation equipment, several companies can be distinguished.

The German company appeared in 1917 as a workshop for the production of agricultural machinery, and 10 years later its founder Johann Wissmann developed and produced the first boiler. Until now, the company is headed by one of the family representatives, already in the third generation.

Today, Viessmann includes several companies specializing in heating systems, as well as ventilation and refrigeration systems. Its products are largely produced for export, and production sites are located in 11 countries. The company released its first condensing boiler in 1992.

The small private company was founded by Prussian engineer Johan Vaillant in 1874. Thanks to the extraordinary abilities of the owner, she quickly achieved success. Since 1894, the company began producing gas equipment, and today the Vaillant Group, which has factories in 7 countries, is known all over the world, including for its developments in the field of energy-saving equipment.

Bosch

The workshop, founded in 1886 by the German inventor-researcher Robert Bosch, for a long time had nothing to do with heating boilers. Only in 1929 did the founder of the company decide to restructure it and move to a broader field of activity. Since that time, many enterprises have joined the structure of the corporation, including companies producing household boiler equipment.

The history of the German company Buderus began in 1731, when its founder Johann Wilhelm Buderus rented a small metallurgical plant where cast iron parts for furnaces were produced. In 1898, the company received a patent for its own sectional boilers, and in 1981, it introduced cast-iron condensing equipment. Since 2003, the Buderus trademark has belonged to the Robert Bosch GmbH group of companies.

Baxi

The company appeared in 1866 in England. It was founded in partnership between Richard Baxendaal and Joseph Heald, and the Baxi trademark was used only in 1930 when producing one of the heating systems. Today, boilers made in Italy by Baxi S.p.A., which belongs to one of the enterprises of the Baxi Group holding, are entering the Russian market.

According to statistics, to create autonomous heating in their homes, most Russians purchase gas heating systems, which are rightfully considered the most economical and environmentally friendly.

Modern industry offers a huge selection of boiler equipment, differing in many parameters, among which the most common are thermal power, functionality, method of installation and exhaust gas removal. This publication will cover hot water gas boilers, which have some design differences from traditional heating installations. We are talking about condensing and parapet type boiler equipment.

Energy from steam condensation

To understand what a gas condensing boiler is, you must first consider the operating principle of a traditional boiler system. When gas is burned, heat is released, which heats the heat exchanger and, accordingly, the coolant passing through it. After which, the heated coolant enters the radiators, where heat exchange occurs between the air and the coolant, and combustion products are discharged through the chimney.

From a school chemistry course, everyone knows that combustion is an oxidation process that occurs with a large release of thermal energy. When a gas-air mixture burns, carbon dioxide and water are released, which is in a vapor state. In order to turn water into steam, a colossal amount of energy is expended.

The operating principle of a condensing gas boiler is to convert water vapor found in fuel combustion products back into water. During condensation, steam releases the accumulated heat to the surface of the heat exchanger.

It works like this: the return flow from the heating system enters the condensation heat exchange chamber of the boiler, through which the exhaust gases pass. The temperature of the coolant coming from the system is much lower than the temperature of water vapor from combustion products. The steam condenses on the walls of the heat exchanger, releasing the accumulated thermal energy to the coolant, which, being warm, enters the primary heat exchanger, where it is heated to the nominal temperature.

The heated coolant flows back into the heating system, and the condensate is discharged through the drainage into the sewer system. The acidity of condensate usually does not exceed 3.5 units: discharging it into the sewer does not violate established standards.

For boiler units of this type, the efficiency reaches up to 98%, with lower fuel consumption (compared to traditional installations with the same technical parameters).

The efficiency of the boiler depends on the temperature of the coolant entering the boiler equipment: the lower it is, the higher the efficiency of the device. The operation of this device becomes most efficient at temperatures of forward and reverse coolant flow of 40/30°C.

Parapet installations

In connection with the huge range of heating equipment presented on the Russian market of climate control equipment, many of our compatriots are interested in the question: “What are parapet gas boilers?”

Despite this somewhat tricky name, these are completely energy-independent boiler units, with a sealed combustion chamber, which represent a kind of symbiosis of a gas boiler with a convector. The scope of application of such equipment is wide: from industrial premises to heating city apartments and private houses that do not have a stationary chimney. The removal of combustion products and the supply of air necessary for normal combustion of gas is carried out through a coaxial chimney.

Since this type of heat generator is non-volatile, it will only be used in heating systems with natural coolant circulation.

Structure of a parapet boiler unit:

• Housing made of thick-walled steel. It has an easily removable decorative casing with an inspection door. Thanks to the perforation, this heating device, not connected to the heating system, performs the function of a convector.
• Burner block with gas valve. The unit consists of a main and pilot burner and is mounted on an easily removable frame structure. The pilot burner includes a thermocouple and a spark electrode.
• Sealed combustion chamber.
• Heat exchanger with copper coil.
• Coaxial chimney through which exhaust gases are removed and street air enters.
• Non-volatile automation and regulation unit.

This type of installation is equipped with a thermometer, a piezo ignition system and a smoke-air unit.

A distinctive feature of parapet heat generators is the design of the heat exchanger with a copper or steel water heating coil. Spiral turbolizers are installed in the inner part of the heat exchanger, which are designed to reduce the speed of exhaust gases. This design allows you to significantly increase the contact of heated gases with the surface of the heat exchanger, and, consequently, heat transfer.

How to adjust the operation of a gas installation

Many owners of heating equipment ask how to adjust a parapet boiler? We strongly do not recommend adjusting the boiler yourself. We warn you that this instruction is given for informational purposes only.

Let us immediately make a reservation that interfering with the operation of gas equipment is prohibited by law in our country. Its independent adjustment of operation can lead to a decrease in efficiency, equipment failure and other undesirable consequences. Condensing boilers must be adjusted by specialists who are licensed and experienced in this type of activity.

Adjusting the operation of the boiler, as a rule, consists of adjusting the gas valve. There are two adjustment screws on the burner block (under the decorative panel): adjusting the maximum and minimum gas pressure.

1. With the boiler cold, start the pilot burner.
2. Set the first mode.
3. If the boiler does not start, then turn the minimum pressure screw (see the data sheet for location) until it starts.

You have adjusted the boiler start. The cutoff is adjusted in the same way.

The condensation heat generator is adjusted using a gas analyzer, the probe of which is installed in a special socket in the chimney. The maximum and minimum power is regulated by turning the damper on the gas valve, based on the readings of the gas analyzer: at maximum power, the carbon dioxide content in the flue gases should not exceed 9.5%; residual oxygen – no more than 4%.

Popular models of heat generators

Today, on the domestic market of climate control equipment you can easily find parapet boiler equipment from several Russian, Ukrainian and European manufacturers. The consumer quite often has a problem with the choice. So, a double-circuit parapet gas boiler: which manufacturer is better?

AOGV 13 P DV "ROSS" is a double-circuit heat generator designed to create autonomous heating and hot water supply in domestic and industrial premises.

This model has a power of 13 kW, which is enough to heat a room of 100 m2. Features of this model: steel heat exchanger; reliable Italian automatic equipment; The system can be connected from any side and can operate on both natural and liquefied gas. Small dimensions allow installation of the unit in any convenient place, but no further than 5 m from the external wall. DHW capacity – 4 l/min. Efficiency – 90%; fuel consumption 1.4 m 3 / h. Cost – 23 thousand rubles.

The heating system connection is universal (left or right), gas supply is only on the right. This device can be mounted on a wall, on the floor, and its small size allows it to be installed under a window sill. DHW capacity – 4.1 l/min; Temperature limits in the heating circuit are 40/90°C. Efficiency – 90%. Gas consumption 1.4 m 3 /h. The average cost is 19 thousand rubles.

Aton Compact 12.5 MV – Ukraine. This dual-circuit model has become quite popular thanks to the reliable German Mertik Maxitrol automation and high build quality.

The body of the Aton Compact 12.5 MV boiler unit is covered with powder enamel, which reliably protects it from corrosion and makes it visually attractive. Installation power 12.5 kW; fuel consumption no more than 1.4 m 3 / h; DHW productivity – 300 l/hour. Efficiency 90%. The average cost is 18 thousand rubles.

Choosing the best model and manufacturer is a matter of taste and financial condition of the user. But, a larger number of our compatriots believe that the AOGV 13 P DV “ROSS” heat generator is the best of the parapet models.

If you decide to purchase condensing boiler equipment for heating and creating hot water at home, we recommend that you familiarize yourself with the most popular models.

Vaillant AtmoTEC plus VUW 200-5 is a wall-mounted condensing double-circuit gas boiler from the famous German manufacturer Vaillant Group.

A special feature of this model is the plate design of the heat exchanger in the DHW unit, which eliminates the appearance of scale. The copper main heat exchanger is coated with Supral, which significantly increases heat transfer. Burner material: chromium-nickel steel. The device is equipped with an LCD display. Thermal power of this model is 22.2 kW; DHW – 9.6 l/min; Efficiency – 98%; Cost – 53.5 thousand rubles.

Chaffoteaux TALIA GREEN EVO SYSTEM 12 FF is a condensing heat generator with a power of 13.3 kW. Designed for autonomous heating and creation of hot water supply in apartments and private houses without a stationary chimney.

The peculiarity of this model is the highest efficiency (99%), efficiency (up to 30%), versatility and automation. This installation can work with an indirect heating boiler. Power consumption 105 W. The average cost is 57 thousand rubles.

BAXI DUO-TEC COMPACT 24 GA is a dual-circuit turbocharged model with a closed combustion chamber, made in Italy.

A special feature of this device is the ability to adapt to fuel quality. The boiler is equipped with a stainless steel burner with preliminary creation of a gas-air mixture and adaptive flame control, due to which a reduced composition of CO and NOx is observed in the combustion products. The efficiency of the installation varies depending on the operating mode
97.6-107.6%. Average cost – 60 thousand rubles.

Based on user reviews, the best condensing boiler in its class is the Vaillant AtmoTEC plus VUW 200-5.

Advice: making the right choice of heating device is a rather difficult task, especially for a person who has not encountered these devices. In any case, before purchasing a gas boiler, consult a professional.

They create a comfortable indoor microclimate and are a highly efficient heating system. Compared to traditional boilers, condensing wall-mounted boilers have an undeniable advantage - saving gas consumption by approximately 11-15%.

A double-circuit condensing gas boiler, like a single-circuit condensing boiler, works to heat the room using thermal energy released after complete combustion of the energy carrier has occurred. Inside the economizer there are combustion products that do not disappear, but turn into condensate and are used in the process of heat release.

A gas wall-mounted condensing boiler uses fuel energy to the maximum, resulting in real savings on space heating.

Operating principle, types of condensing boilers. Main Components

The essence of the operation of condensing boilers is that they take heat from both gas and combustion products. In an ordinary gas boiler, very hot combustion products go into the chimney, which are released into the atmosphere through the chimney. A certain percentage of heat is lost because steam leaves along with the gases.

1. First of all, this is a tank for collecting condensate, into which the condensate enters through a separate drain.
2. Burner – regulates the supply of air and gas.
3. Management control system.
4. The heat exchanger is a part of the boiler that is made of acid- and corrosion-resistant materials (acid-resistant steel, aluminum-silicon alloy), because condensate is a light acid. Some models use main and condensing heat exchangers.

Performance Benefits of Condensing Boilers

A gas wall-mounted condensing boiler, like a floor-standing one, has a number of positive properties:

• almost silent operation. The design features of the boiler help eliminate noise effects, which is very convenient when using it inside a living space;
• maximum power is achieved at low heating temperatures;
• environmental friendliness and long service life. Thanks to high-quality materials, the service life of such boilers is 2 or more times longer than the service life of conventional gas boilers. And new burner design technologies significantly reduce the amount of harmful emissions;
• efficiency due to the possibility of modulating the boiler power. The savings compared to traditional analogues are approximately 10%.

These are not all the advantages of condensing gas boilers, however, these are its main positive characteristics that will guide and help you when choosing.

Wall-mounted condensing double-circuit gas boilers, like single-circuit gas boilers, are used either in conjunction with a heated floor system or for radiator heating.

Disadvantages of condensing boilers. Main Components

Naturally, like any other technology, they have condensation disadvantages. Condensing boilers, disadvantages:

• price. Condensing gas boilers are on average 50% more expensive than conventional gas boilers;
• the need to install a separate condensate tank. In these boilers, condensate cannot be drained into a septic tank, because it will immediately kill all bacteria in the septic tank. Therefore, you will have to install a special tank of a certain volume;
• ineffective at very low temperatures.

These disadvantages of condensing gas boilers should definitely be taken into account before purchasing and installing them. Before purchasing, you need to find out what a condensing gas boiler is, the principles of operation, and, already knowing all the pros and cons, you can make your choice either in the direction of efficiency or in the direction of quality and efficiency.

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The principle of operation of a gas boiler

Many people know that a heating system running on natural gas is the most economical and efficient way to heat rooms. But what’s strange is that the use of gas seems to suit everyone today, but high and stringent energy consumption requirements set certain restrictions. Therefore, condensing boilers occupy a special place in the heating equipment market. By the way, in some European countries the law prohibits the use of other types of heating gas appliances, except condensing ones. Let's try to understand gas condensing boilers, the principle of their operation, advantages and disadvantages.

Principle of operation

First of all, we will be interested in the operating principle of this type of boiler. To show how it differs from conventional units, it is necessary to understand the operating features of the latter.

What's going on in them?

• Gas as fuel is supplied through the burner to the combustion chamber, where it is burned. In this case, the released thermal energy heats the metal heat exchanger in which the coolant moves.
• Giving up part of the thermal energy, the flue gases pass into the chimney and are discharged through it to the street.

It would seem that it could be simpler. But there is one very important nuance here. In order for the draft in the chimney to be appropriate and condensation not to form or accumulate in it, it is necessary that the temperature of the flue gases drops from 200C to 140C. That is, there should be an intensive release of thermal energy to the heat exchanger. But take into account the fact that the temperature of the exhaust gases should not be lower than this level.

In fact, a temperature of 140C is quite a serious potential, which simply evaporates into the atmosphere. The thermal energy contained in the exhaust gases is not spent for its intended purpose. Moreover, inside the flue gases there are always moist air vapors, which also have a certain temperature potential. That's why condensing boilers were invented, in which all these nuances were collected and used.

Moisture collects inside a gas condensing boiler, which, when condensing, releases part of the energy used to heat the additional heat exchanger.

Device

So, it is clear that the design of a condensing gas boiler has two heat exchangers. The first one works according to the standard principle, that is, it is heated by combustible fuel. It is here that the main selection of thermal energy occurs. The second, which is called condensation, takes away the secondary energy of condensed moist air vapor.

The design of a condensing heat exchanger is quite complex. After all, the temperature of the exhaust gases and condensate is not very high, so care must be taken to remove as much heat as possible.

There are several technical solutions that help achieve the desired result:

• Increasing the temperature sampling area. To do this, fins in the form of spirals are welded to the heat exchanger.
• Internal cavities with different sections are used. This makes it possible to intensively extract thermal energy by reducing the volume of the coolant flow passed through.
• A secondary heat exchanger is installed on the return circuit of the heating system. In this way, rapid condensation of wet vapors from exhaust gases is achieved by reducing the dew point. It turns out that the coolant enters the heating gas boiler already heated. And this affects the reduction of fuel consumption and the efficiency of the unit itself.

If we consider the operating principle of this type of unit from the perspective of a traditional boiler, then a kind of recovery occurs in it, which is usually used in air conditioning systems of buildings.

I would like to add that manufacturers install only high-tech burners in the design of a condensing gas boiler, with the help of which optimal mixing of main gas and air is achieved. This again increases the efficiency of the gas apparatus.

Pros of a condensing unit

Wall-mounted gas condensing boiler Buderus

What does all this lead to when comparing traditional and condensing gas boilers?

1. The fuel consumption efficiency of a gas condensing boiler is 20% higher than that of a traditional one.
2. Emissions of carbon monoxide and other combustion products are reduced by almost 70%.

That's what's surprising. The principle of operation of the boiler and its design were invented about a century ago. But only now its use has become possible. The fact is that the metal components and structures of the device could not withstand for long the serious loads associated with the process of condensation of wet vapors and high temperatures.

Currently, these problems have been solved through the use of corrosion-resistant materials in boilers. After all, the resulting condensate is a chemically active substance, which in a short period of time destroys any durable materials. Therefore, boilers of this model use either stainless steel or silumin - an alloy of aluminum and silicon.

If we talk about the external differences between the two models, then it will be difficult for an inexperienced person to do this. But condensing gas boilers are wall-mounted units with a closed combustion chamber. Anyone who has an idea of ​​what we are talking about will understand how many advantages are added only due to these two indicators.

The real state of affairs

Boiler structure

So, condensing gas boilers are more economical - there is no dispute here. But you will still have to pay at least once for this savings. These models are one and a half times more expensive than traditional ones. This is the first.

Second. I would like to draw your attention to some positions that are not striking at first glance. And even some experts do not always pay attention to them. For example, a condensing boiler - a wall-mounted version - has a power rating in the range of 20–110 kW. Traditional wall-mounted units have more modest performance - up to a maximum of 36 kW.

Can you imagine that a small double-circuit condensing apparatus is capable of providing heat and hot water for household needs to a large private house? For example, with a total area of ​​800 m². If you use a traditional heating unit, then only the floor type.

Based on this, you can compare the cost of the two models. It almost levels out. But condensation models have much more advantages:

• Fuel economy.
• Reducing harmful emissions into the atmosphere.
• Efficiency of equipment operation.
• In addition, there is no need to allocate a separate room for them to organize a boiler room, as is usually the case with floor-standing units.

The most important thing is that the efficiency of the device depends on how intensively it is used. After all, the lower the temperature of the coolant in the return circuit, the more complete the condensation in the secondary heat exchanger, the more thermal energy is released, and the higher the efficiency of the equipment becomes. This is why this type of heating device is more cost-effective in so-called low-temperature heating systems - heated floors as an example.

Gas boiler diagram

But in reality, Russian operating conditions are completely different from those in Europe. For example, when the temperature outside the window is minus 20–50C, it is necessary to increase the temperature of the coolant. This can be done only by increasing fuel consumption, because the main source of thermal energy is burned gas. This means that the temperature of the coolant in the return circuit will not drop below 60C. With this indicator, we cannot talk about condensation of wet vapors. That is, the condensing gas boiler you installed begins to work like a regular one. So is it worth purchasing such an expensive device?

However, we will not diminish the advantages of condensation models. Even when operating in this mode, they are more economical than traditional ones. True, at first glance, the savings are not very large - up to 5%, but if you recalculate the annual gas consumption, the amount will be impressive. In addition, the boiler is designed in such a way that even with a maximum drop in gas pressure in the pipe line, it will continue to operate. Efficiency, if it falls, will be insignificant.

Conclusion on the topic

Anyone who considers himself a frugal person and keeps the expenses of the family budget under tight control should purchase a condensing gas boiler for heating and hot water in his own home. With the help of such a unit, you can save a lot on fuel consumption without reducing such an indicator as efficiency. Moreover, gas prices are rising every year.