The chimney is one of the most important parts in the design of a boiler house based on any boilers operating on fuel combustion, including condensing ones. Correct design, material selection and quality installation chimney - necessary conditions for a long and efficient operation of the boiler house as a whole.
Main feature flue gas from condensing boilers is their low temperature compared to flue gases from traditional boilers. In turn, the low temperature leads to the obligatory formation of a certain amount of condensate in the chimney. It is these two factors - low temperature and condensation - that are decisive when choosing a chimney material for condensing boiler... In addition, the need to ensure constant removal of condensed moisture must be taken into account in the design and geometry of the chimneys.
Against the background of the above, we will analyze three main aspects regarding chimneys for condensing boilers:
The two most common materials used to make chimneys for condensing boilers are flame retardant polypropylene and stainless steel.
In domestic applications, PPs chimneys are the most affordable and convenient in terms of installation. Generally speaking, polypropylene chimneys are also used with traditional boilers the most modern designs, but still the service life in this case is limited due to the relatively high temperature flue gases.
In the case of condensing boilers, the emission temperature is low enough to have no influence on the strength of the chimneys. In addition, polypropylene is inert to the acidic composition of condensate formed during combustion of hydrocarbon fuel. That is, from the point of view of durability, this material is ideal for use with condensing boilers.
Another feature of chimneys for condensing boilers is the requirement to operate under overpressure... That is, the connections of the elements must be tight. Typically, silicone seals are used to ensure tightness. Polypropylene is convenient here because, due to its elasticity, it does not require the use of additional clamping clamps, unlike stainless steel.
The main disadvantage of this material is its vulnerability to ultraviolet radiation, that is, such chimneys cannot be laid outdoors in the open.
It is also important to note that polypropylene must be fire resistant. This is usually indicated by the letter “s” in the material designation (PPs). This type of polypropylene is more resistant to high temperatures and, just as important from a safety point of view, does not support combustion.
In past years, the mistake of using ordinary polypropylene sewer pressure pipes for the installation of a chimney was quite common in order to reduce the cost of the material. In no case should this be done for the reasons indicated above.
Acid resistant stainless steel grades are the second most popular chimney material for condensing boilers in domestic applications, and the main one in the industrial and commercial segment!
The basic requirements are the same: work under excess pressure and resistance to chemical composition condensate. In terms of temperature, stainless steel provides a huge margin of safety.
Three main constructive type chimneys, each of which has a specific area of application:
From the name it is clear that these are just pipes and fittings made of the corresponding material. It can only be used indoors or in heat-insulated ducts (for example chimneys during reconstruction). Usually used for flue gas emission when air is drawn from the boiler room.
It is often also used for the manufacture of a channel for supplying combustion air from the street. These air ducts, of course, do not have special requirements for temperature and chemical resistance and tightness. That is, they can be made from almost any available material. However, from the point of view of uniformity and ease of installation, the same type of single-walled chimney is usually used as for flue gas discharge.
Single-wall chimneys can never be used outdoors. The main problem is the constant formation of condensation in the duct. From the point of view of chemical resistance, as noted above, this is not scary, but there is a great danger of freezing of the liquid inside the chimney and, as a consequence, a narrowing of the flow section of the pipe. The drop in natural draft due to cooling of flue gases is not critical for this type of boilers, since they have powerful fans that provide a high value of the residual pressure.
Elements of this type of chimney consist of two concentric pipes of different diameters, the space between which is filled with heat-insulating material, usually stone wool not supporting combustion.
There are no special requirements for acid and heat resistance to the outer pipe, only resistance to atmospheric conditions (precipitation, ultraviolet light) and mechanical strength are needed. Therefore, in the case of double-walled stainless steel chimneys, the inner and outer pipes are usually made of different steel grades to optimize cost. There are options with execution outer pipe made of aluminum.
Double-walled chimneys can be used both indoors and outdoors.
Due to the low temperature of the flue gases and the absence of the likelihood of burns, in the case of condensing boilers, only the outer part of the chimney is usually performed with a double-walled option, and for the inner one, a conventional single-walled pipe can be used.
Again, based on the name, it is clear what this chimney is: two concentric pipes with an empty space between them.
The main feature of this type is that it is used both for the discharge of flue gases (through inner tube) and for intake of combustion air (through the space between the pipes). Accordingly, when using it, it is not required to constantly ensure the flow of combustion air into the boiler room. In addition, the incoming air is heated by the flue gases, thereby increasing the overall efficiency of the boiler room.
Laying coaxial chimneys is also allowed only indoors, the length of the outdoor section in our conditions should be no more than one meter. A common problem in conditions cold winter is the freezing of ice at the end of the chimney. This happens due to the sharp cooling of the flue gases at the outlet when in contact with cold air entering the combustion through the gap between the pipes. To solve this problem, you can cut the section of the outer pipe in the zone of the end of the chimney in order to space the emission of flue gases and air intake; or use the factory winter options the end of the coaxial pipe.
This type of chimney is made from both plastic and stainless steel.
All chimney schemes for condensing boilers are divided into two main types: with combustion air intake from the room and from the street. Naturally, in the domestic regulatory documents These types of smoke exhaust and the requirements for them are described, but in the documentation for the boilers, names are usually found according to European standards. A chimney with air intake from the boiler room is designated as "Bxx", from the street - as "Cxx". The first index varies depending on the specific scheme, the second - on the location of the fan relative to the boiler heat exchanger. In all modern condensing boilers, the fan is located in front of the heat exchanger, which is indicated by the index “3”. Below are the basic diagrams using the example of wall-mounted boilers:
For domestic capacities, the calculation of the chimney is usually not necessary, it is enough to follow the recommendations of the boiler manufacturer for maximum length taking into account shaped elements (elbows, tees, etc.). In the case of industrial boiler rooms, the calculation of the smoke exhaust is mandatory, you can contact the chimney manufacturer for it.
| The easiest way to organize the flue gas outlet. Almost always used for large capacity boilers: industrial or commercial, when floor-standing boilers are used. It is also often found in household use. There are two main requirements when using such schemes: ensuring the necessary air flow into the boiler room and its purity. For boiler houses of large capacities, this is usually not a problem, since these points are carefully taken into account at the design stage. In private boiler rooms, a situation often occurs when a sufficient air flow is not ensured; or it is carried out through adjacent rooms, where, after starting the boiler, they continue Finishing work, which contributes to the presence of fine dust in the air and clogging of the internal elements of the boiler. Naturally, this state of affairs should be avoided or special air filters on boilers. |
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In this case chimney must be brought out above the roof level from the zone of the so-called “wind support”.
This is necessary in order to exclude the influence of fluctuations in air pressure on the smoke exhaust process.
In this case, two main subtypes of the chimney are used: coaxial and separate.
As mentioned above, it is distributed mainly in household use with wall-mounted boilers... In a private house, a coaxial chimney is especially convenient because it is enough to simply bring it horizontally behind the wall, without constructing a vertical trunk extending beyond the roof level. Perhaps this is due to the fact that the air intake and smoke discharge areas are located side by side in the same pressure zone, and, thus, are not affected by the wind.
There remains, however, the question of dispersion of flue gases in the atmosphere. The emissions of modern condensing boilers are environmentally friendly, but the chimney must comply with the standards for distances to windows, doors, ventilation grilles and neighboring land tenure plots. In order to combine the convenience of installing a coaxial chimney indoors and using a double-walled chimney outdoors, you can use special adapter kits.
In the case of modernization of an existing boiler room with brick chimneys, there is a variant with a coaxial pipe up to the zone of this chimney. Next, a new stainless steel pipe is laid inside it (single-wall can be used). Air intake is carried out through the gap between the steel pipe and the brick chimney.
The most varied option in terms of execution options for organizing a chimney. Nevertheless, it is rare in private construction and in industrial boiler houses. Since for condensing boilers in the first case it is usually easier to use a coaxial chimney, in the second - air intake from the room.
It is often found in apartment buildings with separate heat generators for each apartment, according to the following scheme: 
For the selection and purchase of a chimney for a condensing boiler, please contact our
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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 make it possible 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, public corridors, rooms with insufficient ceiling height, small volume and the absence of windows (transoms, vents) are not accepted in advance. 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, the hooks included in the delivery set are usually used. 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 the short circuit of the flame control electrodes to the boiler body 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 using a level gauge.
Most errors in the installation of condensing boilers are due to a violation of the manufacturer's recommendations or neglect of the 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 flue gas temperatures 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 hung 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 the low temperature of the flue gases is one of the features of such boilers. The mistake is that the sewer pipes are not designed for continuous operation at high temperatures (80 ° C and higher). 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. In this case, human lives are at risk and damage to chimneys is caused due to their soaking from condensation and gradual destruction. In this regard, the use of sewer pipes as chimneys for condensing boilers is unsafe and strictly prohibited.
Incorrect slope of 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 correct ways of organizing the 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 drains through 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. The emission of flue gases from condensing boilers into 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 a sealing 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 disrupt 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, there is a temptation to save money on the chimney and instead of “casing” the existing chimney and installing a separate smoke extraction 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 malfunction of the boiler, its premature wear and tear and failure.
The second violation is typical for a 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, the minimum distances from the chimney terminals to the nearest obstacles must also be taken into account.
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 form 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. The neutralization reaction does not harm the 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. IN 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 the 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 request 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 CR4 thermostat can be set for a 7-day heating and DHW program. There are 3 adjustable temperature levels and 5 factory heating programs. The display of the 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 cables during installation, which is especially important when reconstructing heating systems.
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Viewed: 45 731It should be your desire to follow the latest design advances when installing a condensing gas heating boiler. The fact is that ordinary gas boilers, without which no serious system is inconceivable autonomous heating country house do not fully exploit the full potential of such an energy source as gas. That is why, even best models gas heating boilers have an efficiency not higher than 80%. Part of the energy has to be taken out and simply thrown out through the collector.
But, it is possible to squeeze additional dividends out of gas in the form of kilocalories of energy.
The idea is based on the following postulates:
And so it was done - the newest gas heating boilers condensing type. Boilers, which are so widely gaining popularity that according to statistics, more than 30% of all gas boilers in Germany are compensatory.
Born at a time when increased design requirements began to be imposed on products created in the world, condensing boilers are developed with an emphasis on this characteristic - they all look terribly attractive.
Well, and what is hidden inside, thanks to such " double cleaning»Gas and allows you to achieve a real design efficiency from 105 to 110%. In other words, condensing boilers, in essence, the operation process, are double-circuit.
Useful advice! Unfortunately, we cannot say about the same prevalence of the presented boilers in our country as in Germany. Therefore, if you decide to install such a boiler, first of all, choose a worthy model, and most importantly, a worthy supplier and adjuster of the purchased boiler. Frankly speaking, the overwhelming majority of companies have neither experience with such boilers, nor the appropriate personnel for its further maintenance.
Among the advantages are the following:
But one must be aware that such boilers also have some drawbacks, more than an everyday plan:
Despite the fact that these boilers were originally designed as double-circuit, there are also single-circuit models. But most importantly, several modifications of condensing boilers have been developed, depending on the place of their installation.
There are modifications:
Useful advice! If you decide to purchase a gas condensing boiler for industrial use, most likely you will need to choose a model of direct, or they say, "wet", impact on the coolant flow. The efficiency of such boilers is even higher, but their use is still limited to a small supply market. At home, boilers of indirect, or "dry", impact on the coolant, without contact with it, are universally used.
With your own hands, you are unlikely to succeed. This is a too demanding technique, serving for too demanding tasks. Even though you will have installation and operating instructions at your disposal, even though you view all the photos and videos on our website, you still have to contact the professionals for detailed advice.
But to understand the algorithm of operation of condensing boilers and choose the necessary one, according to the power and appearance, this is already for you. In any case, take the choice very responsibly, the price of a mistake is quite high and is expressed not only in the quality of heating your home, in considerable lost financial resources, but also in discrediting such an important thing as the introduction of the most advanced achievements of designers and designers into our life. ...
