How to install a condensing gas boiler. Installation of condensing boilers. Reduction of harmful emissions

18.10.2019

To understand how profitable condensing heating boilers are in use, it is necessary first of all to consider their principle of operation. One of the features in this case is the receipt of additional heat, which is the result of the condensation of combustion products. This phenomenon occurs due to a decrease in temperatures in the combustion chamber to 100-110 degrees, which cannot occur in a conventional chimney due to a strong decrease in thrust.

Therefore, in order to achieve maximum use fuel energy should connect the work of hidden resources. Latent heat is that part of it that is brought out along with water vapor and smoke. Such heat losses may seem insignificant, but in fact, their preservation can significantly increase the efficiency of the heating structure.

The efficiency of a condensing boiler is higher due to the fact that, compared to a conventional design unit, it condenses the steam released during combustion. Further, this steam is mixed with smoke, and the energy released in this case is directed to ensure additional heating of the coolant.

Important! In order for condensation to occur, it is necessary to provide a temperature difference between the vapor and the surface with which it is in contact. Thus, cooling, the vapor passes into a liquid state, reaching the dew point. To ensure an efficient condensation process, it is necessary to ensure that the temperature drops to 60 degrees Celsius.

Design features

The work of the ordinary gas boiler is as follows: when the fuel is burned, the coolant is heated and the combustion products are released into the atmosphere through the chimney. Any unit long burning in practice proves the low efficiency of such a scheme. Therefore, to increase efficiency, there are several significant changes in the design of condensing-type units:

For effective cooling of smoke, another chamber is provided in the design. It is fed into it after the fuel burns out in the furnace.
Adjustment of the intensity of the flame thanks to the installed modular burner.
The system has an additional heat exchanger, thanks to which water is circulated from the return pipe. The temperature difference contributes to the condensation of steam, in which heat is actively released, heating the coolant.
Removal of the cooled smoke is carried out by means of an external contour of a coaxial cable. The system also has an internal circuit used to supply oxygen.
Condensate is collected in a specially designed container.
A fan is installed in front of the burner, due to which the gas is better saturated with oxygen.

The principle of operation of such boilers on video

Advice! In order to save money, the chimney for such a boiler can be made of plastic. Since, due to the design features, the temperature of the exhaust air does not exceed 40 degrees, then plastic pipe will do the job perfectly.

Advantages and disadvantages

Now let's take a closer look at the pros and cons of condensing boilers. The design has several obvious advantages:

Both floor and wall condensing gas boilers have a higher power in comparison with conventional units.
Substantial fuel savings, achievable due to original design burners. Thanks to it, it is possible to accurately regulate the operation of the unit.
The minimum amount of harmful emissions into the atmosphere.
Heat loss in the volume of not more than 2% of the total heat.
High compactness. Even a floor condenser will be significantly more compact than its counterpart of a traditional design.
A double-circuit boiler of this type is great for houses with a "warm floor" system.

Durability due to the high quality of the materials used and the competent setting of the operating mode.

Important! Such units are most effective when used in houses whose area exceeds 200 m2. In this case, there is a large difference in return and supply temperatures, and the efficiency of the device increases significantly when the low-temperature return branch of the coolant is heated. In addition, the larger the heated area, the more obvious the savings when using such equipment.

The disadvantages of this type of boilers include the following:

A sealed chimney equipped with forced ventilation is required.
A high level of efficiency is achievable only in low temperature systems heating.
Energy dependence.
High cost compared to traditional designs.

Mounting Features

Installing a condensing unit involves several important nuances. And the first one is the choice of location. The best option in this case, a specially designated room will become, but if it is not there, then installation can be carried out in the kitchen.

Advice! The walls of the room in which the unit will be installed must be tiled. The floor must also be non-combustible. There must be an exhaust hood in the room.

Hinged structures are fixed on the wall using dowels. The correct location of the boiler is achieved if its lower part has a slightly greater indentation from the wall than the upper one.

Chimney installation features

Today there is whole line options for connecting the chimney to the heating boiler. But whichever of them is chosen in the end, it is important to maintain high tightness. The design of chimneys for condensing units does not differ significantly from the chimney connection schemes in traditional models.

The main requirements are as follows:

Production material. Chimney such a unit must be made of plastic or stainless steel. The main parameter here is not resistance to elevated temperatures, but acid resistance. The fact is that condensate has the same effect as light acid, therefore it is very important that the material is not afraid of corrosion.

Chimney angle must be such that condensate can flow back into the boiler, but precipitation must not enter it, as this may result in damage to the unit due to a short circuit.

How to organize the correct condensate drainage and avoid installation errors

As mentioned above, the basis for the operation of condensing boilers is the formation of condensate.

Important! The amount of condensate formed directly depends on the power of the equipment. So, during the day, the unit can accumulate up to 50 liters of condensate, which has a low acidity. Therefore, you can drain this liquid directly into the siphon of household waste, which will not cause any harm. environment.

Consider the main mistakes that can be made when installing such equipment:

One of the most blunders is the absence in the system of a container designed to drain condensate, or its unsuitable size. Unfortunately, given error allowed even by experienced professionals.
The wall-mounted boiler is installed on a wall that has a coating that is not protected from fire. This may cause a fire.
The condensate is discharged outside. This is unacceptable, since at sub-zero temperatures, icing of the tube is possible. As a result, the unit may simply lock up and fail.
Lack of gas filters in the system.
The boiler is equipped with a gas meter that does not match its capacity.
During installation, the correct slope of the equipment is not observed.

When installing, be sure to take into account all the above points. Only in this case, the installed unit will function correctly for a long time.

The most popular manufacturers

In today's market heating appliances there are a number of condensing units manufactured by various companies. Consider the most popular manufacturers whose products have proven themselves due to high performance and uninterrupted operation:

Wisman ( Viessmann). The company is one of the world leaders in heating and refrigeration systems. Its products are distinguished by the introduction of new technologies and high performance. Wiesmann is doing an excellent warranty service its technology and carefully cares about the quality of products. True Italian quality at relatively affordable prices.
Vaillant ( Vaillant) is a German manufacturer of heating equipment, which has gained considerable popularity in more than 60 countries around the world. The high quality of Vaillant products is underlined by the conformity international standards. The company annually invests a lot of money in the modernization of its technologies, producing premium-class equipment.

Baksi ( Baxi). Another Italian company specializing in the production of heating equipment. It is one of the European leaders, having been present on the market for more than a decade. Large the lineup and high reliability of the equipment produced by the company - distinctive features this manufacturer.
Buderus (buderus). Known German company which is one of the oldest in Germany. It has been manufacturing heating equipment and accessories for almost 300 years. Today it is one of the undisputed leaders in the world market.

Conclusion

Condensing boilers are an excellent option for home heating. This is a reliable and productive equipment with high efficiency and enviable economy. Best of all, such units are suitable for heating private houses of a large area, since in this case the level of efficiency increases significantly.

E. Chernyak

So that the consumer remembers the boiler only during the passage of the planned Maintenance It is not enough just to choose high-quality and reliable equipment. It is important to mount it correctly, because often an illiterate installation leads to equipment failure and a ban on its delivery for warranty service. This is especially true when installing expensive condensing equipment.

General principles

pledge correct installation boiler and its further normal operation is the competent design of the entire heating system. It's about that, for example, significant efficiency and comfort of equipment cannot be achieved without the installation of temperature controllers. Modern technologies allow you to create zonal heating systems. In this case, in each heating zone under the control of the sensor room temperature maintained its own microclimate.

The temperature of the condensing heat exchanger must be below the dew point of the exhaust gases, and the formation of reactive liquid condensate on its surface is not only normal, but also necessary. Moreover, it must be taken out in one way or another and neutralized. Flue gas evacuation systems must be made of corrosion-resistant materials.

When installing systems with condensing boilers, it is important to accurately calculate the heat loss of the building and design heating, taking into account the use of such equipment.

To reduce the required coolant temperature, additional measures to reduce heat loss are important - thermal insulation of enclosing structures, installation of windows with multi-layer glazing.

Place for the boiler

Guided by regulatory documents, a suitable room is determined. At the same time, options for installing a boiler in bedrooms, bathrooms, common use corridors, rooms with insufficient ceiling height, small volume and lack of windows (transoms, vents) are not accepted in advance. The most suitable places are the kitchen or a separate non-residential premises of sufficient volume, with opening windows or vents (Fig. 2). The presence of sewerage in the room is highly recommended.

Rice. 2. The room for the boiler must have opening windows

When hanging the boiler on the wall, the hooks included in the delivery are usually used. They are attached to the wall with dowels. Then the unit itself is hung on these hooks. It is unacceptable if the upper edge of the boiler is further away from the wall than the lower one, that is, in the common folk “littered”. For a traditional boiler, a forward roll of 0.5-1.0 cm per 1 m does not represent a significant danger, but in the case of a condensing boiler, the situation is different. After all, the condensation module is rigidly fixed to the frame. During operation of the boiler in the secondary chamber of the module (economizer section), water vapor condenses from the combustion products. The resulting condensate is collected in a molded pan and discharged first into the siphon and then into the sewer (Fig. 3).

Rice. 3. Formation and drainage of condensate from the condensing boiler module

When the top of the boiler tilts forward, the condensate overflows into the primary chamber, comes into contact with the heat exchanger tubes and begins to evaporate intensively. This leads to a short circuit of the flame control electrodes on the boiler body and its blocking.

Thus, when fixing the boiler on standard hooks, it is necessary to carefully check the verticality of the boiler and, if necessary, align it. The forward roll of the boiler is unacceptable. Also, the deviation of the boiler to the side is not allowed.

Deviations from the vertical position are checked using a level gauge.

Chimney Requirements

Most errors during the installation of condensing boilers occur due to violation of the manufacturer's recommendations or neglect of smoke exhaust standards.

Often there are violations due to the use of coaxial pipes or separate sets from traditional boilers. The material for the manufacture of coaxial pipes of traditional boilers are aluminum alloys and steel. Their purpose is to withstand high temperatures of the emission of combustion products (110 ° C and above). The specifics of the operation of condensing boilers are low flue gas temperatures in normal conditions (40 - 90 ° C), while often below the dew point temperature (57 - 60 ° C, depending on the excess air coefficient). Condensation of water vapor from combustion products occurs not only in the boiler module, but also in the chimney. The condensate has a low acidity at pH = 4, but with prolonged exposure to aluminum or steel chimney channels, it can destroy them. Therefore, the chimneys of condensing boilers along the exhaust path are made of special polymers (for example, polypropylene) that are resistant to acid corrosion of condensate and can withstand temperatures up to 120°C. For example, the company Baxi (Italy) supplies for its condensing boilers (Fig. 4), the efficiency of which is 108.9%, a plastic coaxial pipe with a tip 60/100 mm in diameter, 750 mm long. The scope of delivery includes: coupling and gasket; a tip that protects against gusts of wind; decorative overlay stainless steel on the outside of the wall.

Rice. 4. Wall mounted gas condensing boiler

The use of chimney kits from traditional boilers on condensing boilers and vice versa is prohibited.

There are also violations due to the use sewer pipes as chimneys. Due to the rather high cost of special chimneys of condensing boilers, it is often tempting to use sewer pipes, because the low flue gas temperature is one of the features of such boilers. The mistake is that sewer pipes are not designed for continuous operation at high temperatures (80 ° C and above). And the flue gas temperature may be higher than this value, for example, when the boiler is operating in DHW mode. At the same time, the sewer pipes are deformed, the sealing rings dry out and crack, the chimney tract ceases to be tight. At the same time, people's lives are at risk and damage is caused to chimneys due to their soaking from condensate and gradual destruction. In this regard, the use of sewer pipes as chimneys for condensing boilers is unsafe and is strictly prohibited.

Incorrect slope of chimney or air intake pipes. Installation options for condensing boiler chimneys may vary depending on the conditions (Fig. 5), however, the basic rule should be observed - the slope of the chimney pipe should allow condensate to drain back into the boiler module. The slope of the air intake pipe must prevent atmospheric precipitation from entering the boiler body.

Rice. 5. Variants of installation of chimneys in accordance with the European classification for boilers type C (with combustion air intake from the outside or from a common shaft)

On fig. 6 schematically shown right ways organization of chimney and air intake at various types chimney pipes. So, in fig. 6a shows the use of one chimney and the transfer of the boiler to work with air intake from the room. Elbows (if any) are assembled in such a way as to ensure that condensate flows back through the pipe to the condensing module. It is very important to avoid possible places with a negative slope where stagnant condensate will collect and disturb the operation of the fan.

As a special case, a single chimney is used, which exits the boiler straight up without elbows. If you discharge the emission of combustion products into an existing (or common for multi-storey buildings) chimney (Fig. 6 b), then you need to make sure that this chimney can be operated with condensing boilers and has a condensate collector with a siphon at the lowest point. Emission of flue gases from condensing boilers in brick chimneys leads to their destruction due to soaking. Emission into chimneys made of black steel or aluminum leads to their increased corrosion. The most optimal are insulated chimneys made of polypropylene or stainless steel. If the customer has a chimney, for example, a brick one, then it can be “sleeved” polypropylene pipes or stainless steel pipe.

When assembling the chimney, it is very important to follow the order of connection: the next section is inserted into the socket with the sealing ring from above with the smooth side. This allows the condensate to flow back unhindered into the boiler module. But often stainless steel chimneys are assembled from improvised materials, and even with gross violations (the lower pipe enters the socket of the upper one), so the condensate flowing back through the pipe exits through the joints, which in some cases leads to disastrous results. For example, condensate begins to flood the boiler.

In the case of using a standard coaxial kit, it is also necessary to observe the upward slope of the chimney (Fig. 6 c). For wall-mounted boilers of low power, the slope is provided by the design of the end terminal - with a horizontal arrangement of the outer pipe, the inner one has an upward slope.

Structurally, it is possible to install a boiler with a single horizontal discharge behind the wall. The slope, as in the above cases, is ascending (Fig. 6d).

Rice. 6. Options for organizing the correct pipe slopes

On fig. 7 shows diagrams of incorrect installation of chimney and air intake pipes. In this case, the formation of a stagnant zone is possible, which prevents the operation of the fan and leads to blocking of the boiler (Fig. 7 a). In case of installation as in Fig. 7 b or fig. 7v, condensate in large numbers flows out and freezes with the formation of icicles. The location of the air intake pipe as shown in Fig. 7 g, will cause atmospheric moisture to enter the boiler body, and then to block the boiler or short circuit.

Rice. 7. Incorrect installation of chimney slopes

Despite the fact that both DBN and the manufacturer's recommendations strictly regulate the distance from the release terminal to the nearest objects, gross violations of these standards are very often encountered. Among the most common are the low level of the coaxial terminal relative to the ground and the short distance between adjacent terminals.

The first is typical for private cottages. So, for the boiler and related components of the heating system (pumps, collectors, expansion tanks, boilers, etc.), basements are most often allocated. The choice is obvious and correct - useful living space is not taken, all system components can be hidden and they will not violate the design of the premises. After all, placing a bulky boiler with a piping and a hot water boiler in the kitchen is not an entirely aesthetic solution. And although the vast majority of adapted rooms have chimney and ventilation ducts, it is tempting to save on the pipe and instead of “sleeving” the existing chimney and installing a separate smoke removal and air intake kit, bring the coaxial pipe from the boiler directly through the wall. As a result, the distance from the ground to the terminal is often many times less than the regulated one. Such an arrangement, in addition to the danger to people, also contributes to the active absorption of ground dust and sand into the boiler fan, and then their entry into the mixing path and the combustion chamber. In the future, this can lead to disruption of the boiler, its premature wear and failure.

The second violation is typical for the cascade installation of boilers. In this case, the desire to save money often leads to a reduction in the required distance between the terminals or the use of air ducts not intended for such installation. It is clear that without the reconstruction of chimneys, it is forbidden to start up and put on a guarantee such boilers. Therefore, it is best to use the kits offered by the boiler manufacturer. (For example, Baхі offers for cascade installation not only chimney, but also hydraulic accessories, control automation).

Before installing the boiler, it is also necessary to take into account the minimum distances from the chimney terminals to the nearest obstructions.

Condensate drain

The technology used by condensing boilers involves the formation of condensate from water vapor contained in the combustion products. Depending on the temperature regime and the power of the installed boiler, the formation of up to 50 l / day is possible. fluid to be drained into the sewer. The low acidity of the condensate allows it to be drained into the nearest siphon of household waste, which has an increased alkalinity. As a result of the neutralization reaction, no harm is done to the environment. But still, the condensate drainage path must be provided from materials resistant to an acidic environment (polypropylene, PVC).

Among the errors during installation is the removal of condensate to the street. Installers sometimes lead the corrugated tube directly to the street, by analogy with a split air conditioning system. AT winter period this will lead to the blocking of the duct by ice, filling the module with condensate and the boiler going into emergency blocking.

If the sewerage level in the house is significantly higher than the boiler, it is necessary to use special condensate pumps with built-in tanks, such as Conlift units (Fig. 8) offered by the Danish company Grundfos. They will allow, as condensate forms, to raise it to the desired height and drain it into the sewer.

Rice. 8. Installation for removal of condensate Conlift

Security group

Some models of condensing boilers do not have a built-in expansion tank and safety valve. Therefore, they must be installed during installation. Also in this case, a valve for filling the system should be provided. It must be installed on the supply line after the boiler to prevent cold make-up water from entering the heated boiler heat exchanger.

In addition, there are such errors when installing condensing boilers (typical for traditional heat generators):

wiring of the heating system and piping of the boiler with pipes of small diameter;
incorrect gas supply (narrowing of the gas pipeline, the use of a gas meter that does not correspond to the power of the gas meter boilers, the absence of gas filters or their illiterate installation, etc.);
installation of boilers on wooden and other flammable walls without prior protection;
lack of filters on the return line of the boiler and at the inlet of cold tap water;
errors in the organization of power supply (there is no stabilizer or voltage relay at the input to the boiler, there is no ground loop, generators or other power sources are used that do not have a zero phase or produce distorted characteristics, for example, a non-sinusoidal voltage).

Thermostat connection

A modern energy-efficient heating system is impossible without the installation of thermostats. After all, as we have already noted, at low temperatures, condensing boilers work most efficiently. And thermostats allow you to more accurately control the gas valve of the boiler and maintain the temperature of the coolant at the lowest possible level.

The room air temperature controller CR4 manufactured by Honeywell (USA) uses the OpenTherm digital communication protocol to control the boiler (Fig. 9). This technology means remote control of the burner, in which the boiler produces exactly the amount of heat that is required at the moment in response to a proportional request from room thermostat. The digital connection used is noise-immune and protected against misconnection and short circuits. Low safety voltages are used. The OpenTherm communication protocol can be used with boilers from various manufacturers.

Rice. 9. Boiler control with radio thermostat

The CR4 thermostat can be set to a 7-day heating and cooking program hot water. There are 3 adjustable temperature levels and 5 factory heating programs. Display of operating modes of the boiler and diagnostics of faults is provided. There is frost protection.

Radio frequency communication is carried out using the band 868.0-868.8 MHz. Communication range: 100 m in open space, 30 m in a typical residential building. The receiver module is installed next to the boiler or inside it and is connected using a two-wire cable.

Advantages remote control with the help of radio communication lies in the fact that during installation there is no need to lay a cable, which is especially important in the reconstruction of heating systems.

More important articles and news in the Telegram channel AW-therm. Subscribe!

Viewed: 45 731

Heating a house or other building has gone far from its ancient prototype. It has long been no longer necessary to throw firewood or coal into the "insatiable" firebox. But in order to fully realize the advantages of modern equipment, you need to know this very equipment well.

What it is?

A condensing boiler, including a gas-fired one, is designed to solve the problem of replenishing a warm floor. The low (relatively) temperature of the circulating fluid allows this task to be handled efficiently. And also, according to the statements of suppliers, it is possible to reduce spending on the purchase of energy resources over a long period of time. If you turn to the information materials of manufacturers, you can stumble upon references to efficiency at the level of 108-100%. This seems to contradict the laws of thermodynamics, especially since best boilers other types have an efficiency of 90-95%.

The reason for this difference is that conventional gas-fired boilers do not involve an evaporation and condensation stage. The hot gases that have passed through the heat exchanger in the condensing boiler do not fly into the chimney, taking away a few percent of the heat energy that is useless. The solution to the problem was found in lowering the temperature of the outflowing gases to 55 degrees. This temperature is equal to the dew point under normal conditions, when water vapor reaches this point, it condenses and releases thermal energy. So, the main feature of the condensing boiler is the use of energy released during phase transitions.

Advantages and disadvantages

Condensing boilers of modern design do not forget about environmental problems. The use of latent thermal energy avoids the occurrence of condensate. A feature of these systems is the minimum amount of noise and comfort during use. But it is important to understand that a condensing boiler is more expensive than analogues comparable in power. A one-time solid amount allows you to recoup your investment sometime in the future, but it should initially be laid out in full.

In Western European countries, wall-mounted and floor-standing condensing boilers are used very actively., because they calculate long-term consequences. In addition to being economical, equipment operating on this principle is characterized by increased safety. This setting is supported by the built-in electronic system. Numeric panels have no handles or levers - but they work quite efficiently. Some models are equipped with monitors showing technical parameters, which allows you not to rush back and forth, constantly checking the operation of the system.

Important: the condensing boiler works normally only with an uninterrupted supply of gas or other fuel. It is not provided in all places in Russia, and the inhabitants of such territories, unfortunately, will have to abandon their decision.

Boilers consume approximately 70% less fuel than alternative designs. The wall type of the boiler is more popular than the floor format. But the latter is distinguished by an increased variety of assortment and can warm up an enlarged area.

A condensing boiler differs from a conventional convection apparatus not only in its high efficiency and energy efficiency. The low temperature of the exhaust gases causes such a difference as the possibility of building a plastic chimney. When using fuel, a minimum of harmful substances is released into the atmosphere. Of course, optimal parameters are achieved only with proper installation and quality service. Here much depends on the people themselves.

Principle of operation

The condensing boiler works in such a way that the first heat exchanger is heated by burning fuel, and the second takes heat from the burnt gases. The walls of the secondary apparatus concentrate the steam. But so that the condensate process does not cause corrosion, manufacturers use excellent alloys. They are selected on the principle of chemical resistance.

In order for the secondary heating circuit to collect maximum heat, solutions such as:

attaching additional spirals;
application internal parts various sections;
installation of a condensing heat exchanger on the return flow of the heating system.

It should be noted that the best results when using condensing boilers can only be obtained when using burners of the latest design. In them, the mixing of air and the supply gas is carried out strictly according to the optimal proportion.

Gas condensing boilers with a boiler can solve the problem of hot water supply even when using heating systems with a single-circuit profile.

There are three main options:

embedding the boiler in the boiler itself;
adding external tanks;
the use of boilers operating according to the indirect heating scheme.

According to statistics, a built-in boiler with a capacity of 50 liters allows you to cover the needs of a family of 3 or 4 people in hot water supply by 100% without any difficulty. It should be borne in mind that the presence of a tank narrows the choice of the consumer; it is impossible to hang on the wall, even the strongest, structures with a volume of more than 100 liters. It happens that the boiler is not initially equipped with a boiler - or even equipped, but its operation is not efficient enough. The solution to the problem is the installation of remote tanks. Compatibility with them is provided for almost all wall-mounted gas appliances.

The pipes and pumps that provide circulation in such a system should be designed separately for heating and for hot water supply. The total capacity of the tank is selected according to the capacity of the boilers. If it is not large enough, heating the liquid will take a very long time or will not reach the required value at all. The standard approach to the factory setting of boiler automation implies the primacy of the heating vector. As soon as the coolant cools excessively, the sensor detects this and starts the heating unit.

To keep hot water at the same temperature all the time, boilers with a boiler are equipped with an internal heating element. The controller depends on the electrical supply and is guided by the automation of the boiler itself. A rather interesting question is whether it will be possible to use boilers for heating.

Theoretically, this is possible, but there are a number of pitfalls.

Most drives are equipped with heaters of only 1500 watts. This is enough to warm up 10 square meters. m, but only with solid insulation and not too strong winds, frost.
The heating element, working constantly, will significantly increase the total electricity consumption.
It is possible to push water through the system using standard strapping, but it is not able to compensate for the weakness of the central link.

It should be noted that condensing boilers are not only gas, but also diesel; similar designs are produced even by many eminent manufacturers. The promised efficiency is somewhat lower than that of gas-powered devices, however, 98% is an extremely good indicator. Viessmann Vitorondens 222-F and 200-T are prime examples of such systems. The heat exchanger is made of stainless steel grades. The systems use a universal type burner capable of using any type of liquid fuel.

A small emission of harmful substances is due to the preparation of a mixture of fuel and air in ideal proportions. The developers have managed to equip these devices with a comfortable control unit and sensor equipment. Heat sources can even be built into a perfectly tuned heating system. Modern condensing boilers are almost always equipped with special casings that further reduce noise. Thanks to this, they can be used even in the immediate vicinity of the living space.

The device of the main nodes

Even a general acquaintance with condensing heating equipment shows that it is rather complicated.

Main constituent parts its are:

compartment for burning fuel;
apparatus supplying this fuel;
a fan that improves the injection of the mixture;
original heat exchanger;
cooling chamber, where the mixture of vapors and gases cools down to a temperature of 56-57 degrees;
condensation circuit heat exchanger;
condensate collector;
chimney through which cooled gases move;
a pump that pumps water through the heating system.

The initial heat exchanger mates tightly with the compartment where the fuel burns. In this exchanger, the resulting gases cool slightly, but are still warmer than the dew point. At this phase of special differences from the classical condensation scheme no. Then the smoke mixture artificially moves to heat exchanger No. 2, which cools the gas mass to less than 56 degrees. The condensate, having shared its heat with the heated system, goes through the outlet pipe into the sewer.

But it is important to understand that it is not pure water that condenses inside the boiler, it is saturated with inorganic acids. Since the temperature of the liquid is higher than room temperature, the aggressiveness of even a weak solution increases significantly. Therefore, designers are trying to use resistant substances - stainless steels or an alloy of silicon with aluminum.

To reduce the destructive effect of acids, it is recommended to install cast heat exchangers. A weld, even a very high quality one, turns out to be an entrance gate for caustic substances.

Chimneys are also made from acid-resistant steels or plastics. Horizontal fragments of the gas passage should be inclined at an angle. This solution allows you to redirect the water that appears during the condensation of water vapor back to the boiler. Since the gases leaving the condensing circuit lose their temperature, moisture that has not condensed before will inevitably settle on the walls of the chimney. It is known that heating boilers are required to produce a different amount of heat depending on the time of day and weather conditions.

Adjustment is made using a burner; the modulating type makes this adjustment very easy. There are options with fixed power levels, and then the boiler automation simply gives the command to turn on less often. In most of the most modern devices, however, modulated systems are installed, which are considered more adequate and flexible designs. The amount of fuel consumption is determined primarily by the total power of the heating equipment and the load that it carries. Condensing boilers are designed in such a way that they do not work well in high temperature circuits and require too high an air quality.

Features of choice

The advantages of condensing boilers fully compensate for their individual weaknesses. But in order to realize all their advantages, it is necessary to take into account many subtleties when choosing. The latent heat released during condensation varies depending on the fuel used. If you use methane (in other words, natural gas), the heat released allows you to increase energy output by 11% compared to simple combustion. Liquefied gas adds 9%, and diesel fuel increases heat generation by 6%.

Other types of fuel - not only liquid, but also solid - make a much smaller addition of energy. It is the above types of fuel that are considered the most promising for use in condensing boilers. The condensation of water released during the combustion of solid fuels is given too little effect, since it provides very difficult way. Even among pellet machines, this approach is rare. By increasing the cooling of the flue gases, it is possible to increase the energy extraction.

But the paradox is that when these gases lose heat, it will actually be more difficult to extract heat. The equipment is becoming more and more complex, the actual energy addition does not live up to expectations. In addition, boilers are able to operate at different air temperatures, in different modes. And at the same time, the appearance of condensate in the chimney or in the boiler should be avoided.

It is very important to choose devices with a minimum number of such phenomena.

Considering that convection boilers can only be regulated by the operation of the burner, it is advisable to choose options with the most complex burners and their control units. Bithermic heat exchangers cost less, they are technically simpler. But such devices are much more demanding than conventional ones in terms of the quality of the water passed through them. If it is not large enough, the tubes will fill with a layer of scale very soon. Inevitably, the efficiency of the system will drop.

This danger is less inherent in separate heat exchangers, however, they require the addition of:

secondary heat exchanger;
crane with three moves;
systems that control this crane.

The higher the required power of the boiler, the less auxiliary parts should be. Anticipate their impact on practical work systems are extremely difficult. First of all, as energy production increases, it is necessary to remove built-in expansion tanks and pumps with their surroundings. Most strong boilers do not even have control systems. You can correct the situation by purchasing specially selected additional systems and units.

The latest innovation is pumps that allow you to adjust the rate of rotation of the shaft. Such an apparatus immediately increases the cost of the entire system and complicates it. We'll have to install a more advanced than usual controller. Rarely such equipment is installed in the boiler itself, almost always you have to buy it separately. Therefore, you will have to pay for installation, and for a more thorough configuration.

Nevertheless, experts believe that the future belongs to these pumps. According to their estimates, by 2020 almost all new models of boilers will be equipped with such systems. Chimneys in condensing boilers are already initially different from the usual models. In addition to the use of acid-resistant materials, the use of a coaxial circuit is typical. Most often, two pipes in such circuits are made of plastic.

Important: coaxial chimneys cannot be longer than 5 m, which must be taken into account when choosing, as well as the preferred choice in the wall.

Conventionally, the installation scheme (we consider the Victrix 50 boiler as an example) can be divided into several connection stages:

security kit;
storage boiler;
solar collector;
hydraulic separator.

Let's take a closer look at each stage.

Safety kit

When connecting a boiler with a power of more than 35 kW, European legislation obliges to pay closer attention to safety issues. Therefore, a special safety kit is provided, which includes a safety thermostat, a maximum water pressure switch (4 bar), a pressure gauge and a system filling valve (sleeve for connecting a gas shut-off valve thermocylinder).

There are also fittings for connecting an expansion tank and a sleeve for an immersion alcohol thermometer. The pressure switch and the overheating thermostat are manually unlocked and are connected in series to the boiler power circuit (Fig. 2). The limit of operation of safety devices is configurable and is 3 bar and 105 °C, respectively. This kit allows for a compact, fast and reliable installation of safety devices, and also guarantees reliable protection against accidents under any circumstances.

storage boiler

Since the boilers are single-circuit, it is proposed to use a storage type boiler to meet the needs for hot water. Several standard sizes of boilers are offered, with a capacity from 80 to 200 liters. Boilers have a rectangular body white color. The material for the manufacture of the body and the boiler coil is high quality food grade stainless steel. To reduce heat loss, the boiler is enclosed in high-performance polyurethane foam insulation.

The boilers are equipped with spiral heat exchangers with a large heat exchange surface, which are connected according to the counterflow scheme (Fig. 3). This allows you to quickly heat the accumulated water supply. To ensure the preparation of a large volume of hot water, two 200 l boilers can be used, in which the heating medium and sanitary water circuits are connected in parallel. To connect the boiler to the boiler, you must use a special kit, which consists of adapters and a three-way valve. As in all other mounted boilers, operation in hot water mode is based on the principle of hard DHW priority.

Connecting solar collectors

A feature of 200-liter boilers is the possibility of their work with solar collectors. On fig. 4 shows an example of connecting solar collectors to a heat supply system based on a condensing boiler. High-quality solar collectors and a house heating system coordinated with them allow considering economic use solar energy already like necessary condition building an effective system.

In our latitudes, the total radiation (reflected and direct) in optimal conditions(cloudless clear sky, middle of the day) is a maximum of 1000 W/m 2 . Solar collectors, depending on their type, allow the use of up to 75% of the total radiation. It remains only to note that from our point of view, the combination of a condensing boiler + solar collector(heat pump) - the most promising direction further development autonomous heating systems.

hydraulic separator

Since the boiler is designed to carry a significant heat load, this implies the presence of separate heating circuits with zone control. Therefore, the issue of independent control of circuits becomes relevant. There is a possibility of a change in the amount of coolant circulating through the boiler, which adversely affects its hydraulic regime.

The natural solution in this situation is the use of a hydraulic separator (hydraulic arrow). At the same time, a transition is made to pipes of a larger diameter, which makes it possible to connect the “hydraulic arrow” directly to the supply and return distribution manifolds. For one boiler, a compact solution for this unit is proposed, in the form of a rectangular pipe (Fig. 5).

This unit is located directly under the boiler, which can significantly reduce the installation dimensions. Since the collector is installed horizontally, in order to remove sludge from the heating system, it is obligatory to install a sediment filter on the return line, in front of the collector.

Decided to choose a classic gas boiler for heating, but heard about a new product - a condensing boiler? Yes, the information about him sounds very tempting: the efficiency is already above 100%, everything is beautiful and fabulous. What is the whole point? How was this achieved? Is everything true in his description or is there a drop of tar? We will answer these and other questions in our article. And now - a moment of attention!

Condensing boiler device

Internal organization condensing boiler

In order to understand this issue, let's start from the very beginning, namely, with the design of a condensing boiler. Let's look inside and find out what it consists of.

The most important feature of this type of boilers is the presence of 2 heat exchangers. Otherwise, its design is similar to the design of a conventional gas device and includes:

Water inlet and outlet pipes- through them, cold liquid enters the equipment, heats up, and then through the outlet pipe it is fed to radiators and hot water supply.
Burner- responsible for the supply of gas to the combustion chamber, as well as for the uniform distribution of fuel.
Fan- is installed in front of the burner, and during operation it mixes particles of gas and air so that the resulting mixture burns well.
Heat exchanger No. 1- heats the water flowing through it to a predetermined temperature.
Heat exchanger no. 2- serves to condense moisture and extract heat energy from it. But more on that later.
Pump- to maintain water circulation.

Features of the condensing boiler

In order to better understand the ongoing process, let's take a closer look at principle of combustion and condensation.

What it is? It's simple: when hydrocarbon fuel burns, then as a result of the reaction, 2 substances are released: carbon dioxide CO 2 and water H 2 O. The resulting liquid, being in such a hot environment, almost immediately turns into steam. During the evaporation process, thermal energy, which, however, can be returned and sent additionally to our needs. And you can return it only if the steam is converted back into water.

The process of condensation and release of energy in this case has been known for a long time, but it could not be used in heating equipment. It's all about toxic condensate: during the combustion of gas, a lot of toxic caustic substances and formed carbon dioxide get into the combustion products. Such a vigorous composition very quickly caused corrosion of steel and cast iron heat exchangers.

Condensing units only became popular when rust-resistant steel alloys were invented.

That is why condensing boilers have special heat exchangers, which are made mainly of stainless steel or aluminum-silicon alloy (silumin).

The principle of operation of the condensing boiler

Condensing boiler: working principle

It all starts traditionally:

Water enters the device, gas begins to flow into the combustion chamber. There it is ignited by the ignition system.
During the combustion of fuel, combustion products are formed with high temperature. They pass through the first heat exchanger and heat its walls. And the walls, in turn, give off heat to the water circulating through the heat exchanger.
Further, these gases with a temperature above the dew point exit the heat exchanger No. 1 and enter the heat exchanger No. 2.
In heat exchanger No. 2, gases are cooled by means of water circulating through it from the heating system.
When their temperature equals the dew point temperature (at which condensate occurs), the released water vapor energy is transferred to the liquid that enters the heating equipment. And it was released during condensation.

Operating modes

The heat exchanger of condensing boilers has been specially designed to extract energy from the steam as efficiently as possible. The principle of operation of such a heat exchanger is also special: as we have already said, a heating return pipe is connected to it, through which water flows.

The lower the temperature of the water in this return, the more intense the condensation of moisture.. At the same time, the water temperature in this pipe should not be more than 50 ° C - otherwise the condensation process will not be possible, and the boiler will work like a conventional gas boiler, but still with less gas consumption - the benefit will be about 5%.

Therefore, we present the dependence of the efficiency on the water temperature in this reverse system.

If a liquid with a temperature of 40˚С flows in the direct water supply system, and 30˚С in the return one, then efficiency = 108%.
If the temperatures are 70˚С and 60˚С, then the efficiency will already be lower - 104%.
And at values of 90˚С and 75˚С, it will fall to 98%.

Features of condensate

As we have already said, the condensate that forms during operation has a very aggressive chemical environment. To collect it, the boiler design has a special container that needs to be emptied periodically.

How to be in that case? Of course, in foreign countries, such as Great Britain, Germany, special standards have been established, according to which such condensate is disposed of.

In Russia, there are no clear prohibitions and rules: condensate can be drained into the sewer without any negative consequences.

For example: for 1 day of operation of the boiler with a capacity of 25-30 kW, 25-28 liters of condensate are formed.

If this option disgusts you, then there is an alternative, some models are equipped with special condensate collectors. These containers are filled with magnesium or calcium granules. They absorb liquid, pass it through themselves, thus neutralizing its chemically active environment.

Gas outlet

All condensing models are equipment with closed combustion chamber. There is no other option: an open chamber simply cannot support the combustion process. Due to the presence of the 2nd heat exchanger, which significantly complicates the process of movement of combustion products, and also due to the low temperature of the gases themselves (therefore, they will move very slowly), the rate of air intake in a natural way will be low.

So for the removal of gases, a system of supply and discharge channel is used: it is logical to direct it through the wall / roof of the room, you can build smoke exhaust systems with your own hands.

Pros and cons of a condensing boiler

The list of advantages of this type of equipment is impressive and makes you think about purchasing it very seriously.

Compact dimensions and weight- they can be used even in houses and apartments with a small free area. In addition, you will significantly save on its transportation and installation.
economy- quite a logical plus, because the device of the boiler was created in such a way that to achieve the result it was spent less fuel. And so it is! Costs are less than traditional ones by 30-35%!
Precise modulation - in fact, this means a very careful choice of boiler power depending on external parameters (heat demand, air temperature in the room and outside the window, etc.). This also makes it possible to reduce fuel consumption if the boiler is partially loaded.
Low noise- it is also very pleasant, since the equipment can be placed next to living quarters, without fear that it will disturb the sleep of children, and indeed life in general.
Cascade function- an important aspect, especially if you need to heat a large house, or you will insure yourself in advance against a possible breakdown of the boiler. In this case, it can easily be replaced by another boiler from the cascade.
Reducing the selection of toxic substances into the atmosphere– a condensing boiler is about 70% more environmentally friendly than its traditional counterparts.
Low flue gas temperature- this is also a significant plus, since the low temperature of the combustion products allows you to install plastic chimneys. And their purchase and installation cost is much lower than similar work with classic steel chimneys.

Minuses. Of course, with such a rosy picture, you don’t want to spoil the impression, but still you have to talk about the essential. The point is their price - it is almost 2 times more than conventional heating models.

Of course, the boiler can pay off, but this is influenced by such factors as the intensity of use, temperature conditions etc.

Condensing boiler efficiency

Condensing boiler in the house

In order not to break the brain in vain, we will give an example of how they reached such a figure.

So, as we have already found out, a condensing boiler heats water from 2 types of heat: gas combustion and steam condensation.

Now let's turn to the very form of efficiency - what is it? Physics says: we will get the efficiency if we divide the value of the heat that was released by the heating batteries by the value of the heat that was released during the combustion of gas in the boiler chamber. Well, let's multiply everything by 100%.

Now let's turn to the concept fuel combustion points. Any fuel has 2 points of combustion: higher and inferior.

The high temperature is the sum of the low temperature + the condensing temperature.

Efficiency is determined precisely by the highest temperature.

Heat losses are present in absolutely any device: heat radiation into space during heating, heat loss through distant gases, etc. That is why the energy expended will never turn into heat. This is the reason why the efficiency will always be less than 100%.

However, there is a slightly different calculation system: lower heat 100% is absorbed by heat exchanger No. 1, and heat from condensation 8-11% by heat exchanger No. 2. So it turns out that the efficiency of condensation models according to this scheme is 108-110%.

Operation of the condensing boiler: video

If you have not yet fully figured out how this notorious condensing boiler still works, then we advise you to watch this video. It will bring some clarity: