Have you decided to choose a classic gas boiler for heating, but have you heard about a new product - a condensing boiler? Yes, information about it sounds very tempting: the efficiency is already higher than 100%, everything is beautiful and fabulous. What is the whole point? How did you achieve this? Is everything true in his description or is there a drop of ointment? We will answer these and other questions in our article. Now, just a moment of attention!
In order to understand this issue, let's start from the very beginning, namely, with the design of the condensing boiler. Let's look inside and find out what it consists of.
The most main feature this type of boilers - the presence of 2 heat exchangers. Otherwise, its design is similar to that of a conventional gas device and includes:
In order to more clearly understand the ongoing process, let us dwell in more detail on combustion and condensation principle.
What it is? It's simple: when a hydrocarbon fuel burns, then as a result of the ongoing 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. The evaporation process consumes 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 the 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 the toxic condensate: during the combustion of gas, many toxic corrosive substances and the 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 widespread when rust-resistant steel alloys were invented.
That is why condensing boilers have special heat exchangers, which are mainly made of stainless steel or aluminum-silicon alloy (silumin).
Condensing boiler: working principle It all starts traditionally:
The heat exchanger for condensing boilers has been specially designed in such a way as 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 water temperature in this return, the more intense the condensation of moisture... At the same time, the temperature of the water in this pipe should not be more than 50 ° C - otherwise the condensation process will be impossible, and the boiler will work like a regular 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.
As we have already said, the condensate that forms during operation has a very aggressive chemical environment. To collect it, there is a special container in the boiler structure, which must be emptied periodically.
What should be done in this case? Of course, in foreign countries, such as Great Britain, Germany, special standards have been established, according to which the disposal of such condensate is carried out.
In Russia, there are no clear prohibitions and rules: condensate can be drained into the sewer without any negative consequences.
For example: in 1 day of operation of a 25-30 kW boiler, 25-28 liters of condensate are formed.
If this option hates you, then there is an alternative, some models are equipped with special condensate collectors. Magnesium or calcium granules are poured into these containers. They absorb liquid, let it pass through themselves, thus neutralizing its chemically active environment.
All condensing models are equipment with combustion chamber closed type ... There is no other option: open camera simply will not be able to maintain the combustion process. Due to the presence of a 2nd heat exchanger, which significantly complicates the process of movement of combustion products, as well as due to the low temperature of the gases themselves (therefore, they will move very slowly), the rate of air flow in a natural way will be low.
That's why for the removal of gases, a supply and exhaust channel system 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.
The list of advantages of this type of equipment is impressive and makes you think about purchasing very seriously.
Minuses... Of course, with such a rosy picture, you don't want to spoil the impression, but you still have to talk about the essentials. It's about their price - it's 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 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 combustion points... Any fuel has 2 combustion points: the highest and inferior.
The highest temperature is the sum of the lowest + condensing temperature.
The efficiency is determined precisely by the highest temperature.
Heat loss is present in absolutely any device: heat radiation into space during heating, heat loss through remote gases, etc. That is why the expended energy 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: the lowest heat is absorbed 100% by heat exchanger No. 1, and heat from condensation is 8-11% by heat exchanger No. 2. So it turns out that the efficiency of condensing models according to this scheme is 108-110%.
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 clarify a little:
It is the main element of the chimney system. Used on straight sections to achieve the required height.
There are three types of lengths - 250, 500, 1000 mm. , which provides the ability to select elements in accordance with the design configuration. Chimneys of the "Sandwich" type consist of an inner welded pipe (of various steel grades (AISI 430, 304, 321) of different thicknesses and an outer pipe of a larger diameter made of matt or polished (mirror) stainless steel AISI 430 with a thickness of 0.5 mm or galvanized steel. Between the pipes there is a layer of insulation - non-combustible insulating material based on basalt rocks.
Throttle valve
This is a chimney element used to regulate the draft by partially blocking the chimney channel, and also as a damper on an unexploited fireplace with an open hearth to prevent warm air from leaving the room through the chimney.
It is a pipe with a built-in rotary damper and a handle brought out to the outside.
Mono-thermo transition
This is a chimney element used when connecting different types of chimney systems or when it is necessary to change the diameter of the flue duct.
The transition is installed at the junction of parts of the chimney system with different diameters. As a rule, when changing from a smaller diameter to a larger one, in situations when several heat generators are connected to the main channel of the chimney at different levels
The outlet is the main element of the chimney system, allowing you to change the direction chimney in cases where it is necessary to bypass an obstacle, or turn the chimney in the desired direction. Elbows are made of cylindrical sectors connected at a certain angle.
Tee 90 °
Tee 90 consists of two cylindrical elements connected at an angle by means of spot or seam welding.
When installing a tee on the turn of the chimney from a horizontal or inclined position to a vertical one, a plug or a condensate drain plug is installed in the lower part of the tee that closes the entire system.
A 90 ° T-piece is preferable to use in dry mode, since when the flow of gases slows down during a sharp turn, active condensation can occur.
Tee 45 °
The 45 ° tee consists of two cylindrical elements connected at an angle by means of spot or seam welding.
When installing a tee on the turn of the chimney from a horizontal or inclined position to a vertical one, a plug or a condensate drain plug is installed at the bottom of the tee that closes the entire system.
The 45 ° tee provides Better conditions thrust than the 90 ° tee, since it has a larger angle (135 °) of rotation.
This is an inspection element of the chimney, designed to diagnose the state of the chimney and clean the chimney by removing the products of incomplete combustion of fuel (soot). The revision facilitates the maintenance of the chimney.
As a rule, the revision is installed at the base of the chimney, below the connecting tee, as well as in horizontal sections of the connecting chimney with a length of more than 2 meters.
The revision is a modification of the 90 ° tee equipped with a special cover fixed with a pipe clamp. The revision consists of two cylindrical elements connected at right angles.
Plug
Installed at the bottom of the tee to collect soot and condensate, and can also be removed to remove foreign objects from the chimney.
Cap with condensate drain
Designed to collect and remove condensate products from the smoke channel. It consists of a tubular element, a cone element or a pallet with a hole, connected to each other. The hole is designed for condensate drainage and is equipped with a branch pipe.
Conical ending
If special-purpose elements are not installed at the mouth of the chimney, a conical end should be installed to protect the insulation from atmospheric precipitation.
Thanks to the closure inner pipe and the upper edge of the truncated cone, the access of atmospheric precipitation to the insulation is blocked.
It is used as the end of the chimney to protect it from atmospheric precipitation.
Thermo-thermo transition
These are chimney elements used when connecting different types of chimney systems or when it is necessary to change the diameter of the flue duct.
Transitions are installed at the junction of parts of the chimney system with different diameters. As a rule, when changing from a smaller diameter to a larger one, in situations when several heat generators are connected to the main channel of the chimney at different levels.
E. Chernyak
So that the consumer remembers about the boiler only during 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 the prohibition of its delivery for warranty service. This is especially true when installing expensive condensing technology.
Pledge correct installation the boiler and its further normal operation is the competent design of the entire heating system. The point is that, for example, significant efficiency and comfort of equipment operation cannot be achieved without installing thermostats. Modern technologies allow you to create zonal heating systems. In this case, each heating zone under the control of a room temperature sensor maintains 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 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 temperature of the coolant, it is important additional activities to reduce heat loss - thermal insulation of enclosing structures, installation of windows with multilayer glazing.
Guided by regulatory documents, determine a suitable room. At the same time, options with the installation of a boiler in bedrooms, bathrooms, corridors are not accepted in advance. common use, rooms with insufficient ceiling height, small volume and lack of windows (transom, vents). Most suitable places are a kitchen or a separate non-residential premises of sufficient volume with opening windows or vents (Fig. 2). Indoor sewerage is highly recommended.
Rice. 2. The boiler room must have opening windows
When hanging the boiler on the wall, usually use the hooks included in the delivery set. They are fixed 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 at the same time more distant from the wall than the lower one, that is, in the common folk way, it is “overwhelmed”. For a traditional boiler, a forward roll of 0.5-1.0 cm per 1 m does not pose 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 the operation of the boiler, condensation of water vapor from the combustion products occurs in the secondary chamber of the module (economizer section). The resulting condensate is collected in a molded pallet and discharged first into a siphon, and then into the sewer (Fig. 3).
Rice. 3. Formation and drainage of condensate from the condensing boiler module
When the boiler top rolls 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 drum and its blocking.
Therefore, when attaching the boiler to standard hooks, the verticality of the boiler must be carefully checked and, if necessary, leveled. Tilting the boiler forward is not permissible. Also, the boiler is not allowed to deviate to the side.
Deviations from the vertical position are checked with a level gauge.
Most errors in the installation of condensing boilers are due to a violation of the manufacturer's recommendations or neglect of smoke removal standards.
Often there are violations due to the use of coaxial pipes or separate sets from traditional boilers. The materials for the manufacture of coaxial pipes for traditional boilers are aluminum alloys and steel. Their purpose is to withstand high temperatures of the exhaust of combustion products (110 ° C and above). The specificity of the operation of condensing boilers is low temperatures flue gas in normal modes (40 - 90 ° С), while often below the dew point temperature (57 - 60 ° С, depending on the excess air ratio). 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, Baxi company(Italy) supplies for its condensing boilers (Fig. 4), the efficiency of which is 108.9%, plastic coaxial pipe with a tip with a diameter of 60/100 mm, length 750 mm. The delivery set includes: coupling and gasket; a tip that protects against gusts of wind; decorative stainless steel overlay 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 use sewer pipes as chimneys. Due to the rather high cost of special chimneys for condensing boilers, it is often tempting to use sewer pipes, because low temperature flue gas is one of the features of such boilers. The mistake is that the sewer pipes are not designed for continuous operation when 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 O-rings dry up and crack, the chimney path ceases to be dense. This puts human lives at risk and damages chimneys as they become soaked by condensation and gradually deteriorate. In this regard, the use of sewer pipes as chimneys for condensing boilers is unsafe and strictly prohibited.
Incorrect inclination of the chimney or air intake pipes. The installation options for the chimneys of condensing boilers may vary depending on the conditions (Fig. 5), however, the basic rule must be observed - the slope of the chimney must facilitate the condensate drainage back into the boiler module. The slope of the air intake pipe must prevent the ingress of atmospheric precipitation into the boiler drum.
Rice. 5. Variants of chimney installation in accordance with the European classification for type C boilers (with combustion air intake from the outside or from a common shaft)
In fig. 6 schematically shows the right ways organization of chimney and air intake when different 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. The elbows (if any) are assembled in such a way as to ensure that the condensate flows down the pipe back to the condensation module. It is very important to avoid possible places with a negative slope, where stagnant condensation will collect and interfere with the operation of the fan.
As a special case, a single chimney is used, which exits the boiler straight up without elbows. If we deduce the emission of combustion products into the already existing (or total for multi-storey buildings) chimney (Fig. 6 b), then make sure that this chimney can be operated with condensing boilers and has a condensate collector with a siphon at the lowest point. Flue gas emission from condensing boilers in brick chimneys leads to their destruction due to soaking. Emission into chimneys made of black steel or aluminum leads to 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 "sleeve" polypropylene pipes or a stainless steel pipe.
When assembling the chimney, it is very important to observe the connection order: the next section is inserted into the socket with an O-ring from above smooth side... This allows the condensate to drain unhindered back into the boiler module. But often stainless steel chimneys are assembled from scrap materials, and even with gross violations (the lower pipe enters the bell of the upper one), thus the condensate flowing back through the pipe comes out through the joints, which in some cases leads to disastrous results. For example, condensate starts to fill the boiler.
In the case of using a standard coaxial kit, the upward slope of the chimney must also be observed (Fig. 6 c). For wall-mounted boilers of low power, the slope is provided by the design of the end terminal - with the 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 outlet behind the wall. The slope, as in the above cases, is ascending (Fig. 6 d).
Rice. 6. Options for organizing the correct slopes of pipes
In 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 impedes the operation of the fan and leads to the blocking of the boiler (Fig. 7 a). In case of installation as in fig. 7 b or fig. 7c, a large amount of condensate flows out and freezes with the formation of icicles. The location of the air intake pipe is as shown in fig. 7 g, will lead to ingress of atmospheric moisture into the boiler drum, and then to the boiler blocking or short circuit.
Rice. 7. Incorrect installation of chimney slopes
Despite the fact that both the DBN and the manufacturer's recommendations strictly regulate the distance from the discharge terminal to the nearest objects, gross violations of these standards are often encountered. Among the most common are the coaxial terminal's low ground level and the close distance between adjacent terminals.
The first is typical for private cottages. So, for the boiler and accompanying components heating systems (pumps, collectors, expansion tanks, boilers, etc.) most often highlight semi-basements. The choice is obvious and correct - useful living space is not taken, all components of the system can be hidden and they will not interfere with the design of the premises. After all, placing a bulky boiler with piping and a hot water boiler in the kitchen is not a very aesthetic solution. And although the overwhelming majority of adapted rooms have chimney and ventilation ducts, it is tempting to save money on the chimney and instead of “casing” 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 several times less than the regulated one. This arrangement, in addition to the danger to people, also contributes to the active suction 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 a malfunction of the boiler, its premature wear and tear 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 decrease in the required distance between terminals or the use of air ducts that are not intended for such an installation. It is clear that without the reconstruction of chimneys, such boilers cannot be started up and guaranteed. Therefore, it is best to use the kits provided by the boiler manufacturer. (For example, Baxi offers for a 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 obstacles.
Technology by which they work condensing boilers, implies the formation of condensation from the water vapor contained in the combustion products. Depending on the temperature regime and the capacity of the installed boiler, it is possible to generate up to 50 l / day. liquid that needs to be discharged into the sewer. The low acidity of the condensate allows it to be drained from the nearest siphon of household waste, which has an increased alkalinity. No harm is caused by the neutralization reaction environment... Nevertheless, the condensate drainage tract must be made of materials resistant to acidic environment (polypropylene, PVC).
Among the errors during installation is the drainage of condensate to the street. Installers sometimes lead the corrugated pipe directly to the street, by analogy with a split air conditioning system. V winter period this will lead to blockage of the path with ice, filling of the module with condensate and the exit of the boiler to 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, for example, Conlift units (Fig. 8) offered by the Danish company Grundfos. They will allow, as condensation forms, to raise it to the desired height and drain it into the sewer. 
Rice. 8. Condensate removal unit Conlift
Some condensing boiler models do not have a built-in expansion tank and a safety valve. Therefore, they must be installed during installation. Also in this case, a system filling valve should be provided. It must be located on the flow line after the boiler in order 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):
A modern energy efficient heating system is impossible without the installation of thermostats. After all, as we have already noted, condensing boilers work most efficiently at low temperatures. And thermostats allow you to more accurately control gas valve boiler and maintain the coolant temperature at the lowest possible level.
The room 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 currently required in response to a proportional demand from the room thermostat. The digital connection used is immune to interference and protected against incorrect connection and short circuits. Low safety voltages are used. The OpenTherm communication protocol can be used with boilers from various manufacturers. 
Rice. 9. Boiler control by means of a thermostat with a radio module
The thermostat CR4 can be set for a 7-day heating and cooking program hot water... There are 3 adjustable temperature levels and 5 factory heating programs. Display of boiler operating modes and diagnostics of malfunctions are provided. There is frost protection.
Radio frequency communication is carried out using the 868.0-868.8 MHz band. Communication range: 100 m in open space, 30 m in a typical residential building. The receiving module is installed next to the boiler or inside it and is connected using a two-wire cable.
The advantages of remote control using radio communication are that there is no need to lay a cable during installation, which is especially important when reconstructing heating systems.
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Viewed: 45 731It's time to consider and understand the features of condensing gas boilers ...
Thanks to their high-tech design, condensing boilers make the heating system much more convenient, comfortable and economical. If in conventional devices the combustion products give off only a part of the thermal energy, then in this case this is done to the maximum. The company "Luch Tepla" presents boilers of all types in a large assortment.
Design
Condensing boilers are structurally indistinguishable from typical heating appliances. They are carried out in several versions:
Their design includes a non-standard heat exchanger made on the basis of acid-resistant materials. Usually - from stainless steel or silumin. It looks like a pipe with a complex cross-section and spiral ribs. All this increases the heat exchange area and makes the gas boiler more efficient.
In addition, the condensing unit is equipped with a fan in front of the burner. It "sucks" gas from the gas pipeline, mixes it with air and directs it directly to the burner. The boiler also has a pump with electronic control, which allows you to optimize the heating power, reduce noise from the heat carrier passing through the system and save on electricity.
There are several types of condensing boilers:
Moreover, their power can vary from 20 kW to 100 kW, which is quite enough for household boilers. For office and industrial premises, they are produced in higher capacity and in floor-standing design.
In standard boilers, hot gases are simply released into the atmosphere through the chimney, losing a significant proportion of the unused heat. It is discharged outside together with the waste products in the form of water vapor, which is formed at the time of fuel combustion. It is in the steam that the additional heat energy lies, which the condensing boilers store and then transfer to the heating system.
When cooled, the vapor condenses, that is, it becomes a liquid, and releases a certain amount of heat. This process takes place in a special heat exchanger with an extended area. It is he who "takes" heat for transferring to the heating system. This approach has been known before. But it began to be used relatively recently due to the appearance of corrosion-resistant alloys, which are the basis for the production of condensing boilers.
The efficiency of such gas devices largely depends on the characteristics heating system... The lower the water temperature, the more complete the process of condensation of water vapor takes place. Consequently, the higher is the amount of latent heat that is returned to the system.
In this way, the condensation mode is maintained throughout the entire heating period. Therefore, the most important condition for the functioning of a condensing boiler is the average temperature of the heating medium. For example, at the entrance to the boiler, it should be less than 60 degrees (ideally, up to 57 degrees). This will give better condensation and increase the efficiency of the heating device.
But even if you combine the condensing boiler with the old system, it will still bring tangible savings, since it will be more efficient than the old equipment. This is due to the fact that in our climatic zone the coldest days in total take a little more than 10 percent of the duration of the entire heating period. Optimum condensation is possible on other days.
Advantages
Among the basic advantages of this type of boilers is high efficiency. In this case, it is equal to 108-109 percent when compared with other boilers. Another advantage is that they are more economical. It is approximately 15-20 percent higher than that of standard heating appliances.
