Connecting a coaxial chimney. What is a coaxial chimney for a gas boiler? Requirements for installing a coaxial boiler

Today we will consider in detail the coaxial chimney outlet from a gas boiler, what is its main feature and why should it not be used for solid fuel boilers? This and more will be discussed further. In addition, let's consider important aspects when choosing chimneys, what types there are and their main differences. In addition, attention will be paid to the connection diagram, as well as the selection of the optimal installation option for the installation, taking into account the personal characteristics of the structure.

Understanding the question of what a coaxial chimney is is simple at first glance, but in fact it is a rather complex design in terms of technology. However, having certain knowledge and installation rules, you can install it yourself, the main condition is to adhere to accepted norms and rules.
In simple terms, a coaxial chimney for a gas boiler is a “pipe within a pipe.” Often, such devices are used in closed chambers, heaters, and the like. Main feature This design is due to its technical ease of assembly, because each element is a separate puzzle, which is assembled from several component blocks. The parts are inserted into each other and held there by jumpers pre-provided by the manufacturer, so-called “blind” locks. They do not allow the parts to interact directly, there are no shocks, movements, or sliding of parts.

As already mentioned, the coaxial chimney device consists of two pipes. That is, before us are classic double pipes, between the walls of which there is a space of several centimeters. If you take the middle pipe, then its internal planes are used to remove hot gases, but a gap of several centimeters (the gap) is used to intake fresh air. This is necessary for technical reasons so that the burner itself functions reliably. Thus, the incoming air is already hot, due to heating on the walls of the outlet pipe. Thus, no additional waste is required to heat the incoming air.

A coaxial chimney consists of two pipes

The most interesting thing is that this design allows you to significantly reduce fire danger. After all, the escaping air simultaneously heats the cold air and at the same time cools itself. Often, the outlet of such chimneys is provided immediately behind the wall from the boiler.

Such a device also plays an important role in the combustion process. We have already found out that the air initially arrives heated, which means the heat transfer coefficient increases. In addition, such designs allow the boiler to be completely sealed, thereby preventing gases from entering the building. In simple terms, the boiler is completely localized.

In addition, you can even completely isolate the outlet part using an air “gap”; it will make it possible to avoid serious overheating of the wall and the floors in general. This is especially important for buildings made of wooden materials or subject to fire.

By the way, due to the cooling of the exhaust gases, the overall thrust is noticeably improved.

Types of coaxial pipes

There are not so many types of such pipes, however, we need to talk about them, because they are divided into several classifications. The first of them divides into insulated and non-insulated.

The first option is more suitable for Russian conditions, it is often used in northern latitudes, central Russia, Siberia and the Far East. The latter, not insulated, are in demand in the southern regions, where temperatures rarely drop to sub-zero values for a long time.
In addition, chimneys differ in installation options:

Vertical coaxial duct, chimney for a gas boiler. Often, this method is used only in cases where it is not physically possible to remove the pipe directly from the boiler, that is, on the side of a building, or in a low room with windows or another building nearby.
You already guessed, the second type is a horizontal chimney. The operating principle of a coaxial chimney is equal to the need for ventilation (forced). But, do not forget that the length to which the channel can be output has limitations. As a rule, all manufacturers try to indicate their own parameters for each model, but a “removal” of no more than three meters is generally accepted. Therefore, before planning a design, first familiarize yourself with the characteristics of a particular model.
Sloping chimney. Such options can be found much less often than it might seem. Often, the choice falls on them only if it is not technically possible to install a full-fledged vertical or horizontal outlet. It is worth noting that such designs will have a radically different output and efficiency, in relation to others, less.

Installation options

Depending on the installation option, you must adhere to certain rules specified in the instructions. But, for all types of channels there are some General characteristics and rules:

Initially, choose the type of outlet, focusing on the boiler, its cross-section, characteristics prescribed by the manufacturer; it may turn out that the manufacturer did not specifically provide such an outlet in the design.
To generate and support better traction, it is better to install the outlet slightly higher than the ridge. This rule is more suitable for vertical installation options.
You need to take a very responsible approach to installation, the slightest damage or incorrect installation, can lead to exhaust gases entering the room.
Another nuance, it is generally accepted that the outlet channel must have a diameter larger than the outlet of the boiler.
The heat source should be located one and a half meters below the level of the outlet pipe. The tilt angle is allowed at least 3 degrees. This type of arrangement allows for unhindered “draining” of condensate into a special receiver.
Also note that the channel entrance must be located at a level of at least one and a half meters.

Advantages and disadvantages

Now let’s take a closer look at the advantages of a gas boiler equipped with these types of channels:

The possibility of gases entering the living space is completely eliminated, naturally taking into account correct and qualified work. Such pipes provide for the principle of localizing the combustion chamber, a pipe with incoming air and a pipe that removes exhaust gases.
The air supplied to the chamber does not pass directly into it, but goes around a “ring”, and as it moves through it it heats up, thereby increasing efficiency.
The exhaust smoke is cooled by the incoming cold flow, thereby increasing the level of fire safety. This advantage is of great importance for wooden houses.
A higher percentage of fuel combustion generally increases the level of environmental compliance of the boiler.
This design has smaller dimensions than similar separate pipes, which significantly simplifies and reduces installation time.

Flaws:

The first disadvantage applies to a greater extent to the vertical coaxial chimney, for which the cost is, in general, 40% higher than classical designs. The price of horizontal types is also about 30-35% more expensive.
The second disadvantage is the small maximum length coaxial chimney for a gas boiler. As already said, no more than three meters in a horizontal position and no more than 5-6 meters in a vertical position.
The third disadvantage is that this type of design, which is a cylinder with inserted channels, allows condensation to form to a greater extent. What requires the installation of special receivers, as well as if insulation is necessary. Insulation allows you to practically get rid of excess condensation. Condensation will almost always cause the pipe to become icy severe frost, so initially consider protecting against this, insulation or installing special receivers.

One of the disadvantages of chimneys is their icing in winter time

Coaxial chimney installation diagram

In this section we will look at the two most popular installation options. So, the first option is to install a vertical coaxial chimney in wooden house, according to

SNiPs, the following features of the scheme should be taken into account:

The head should be located at least two meters from the ground.
The norms and rules for installing a coaxial chimney imply the need to make a hole for the pipe, 1-2 cm larger than the cross-section. In wooden walls and ceilings, at least 5 cm.
Distance from doors window openings, ventilation fences, at least 50 cm.
More than 1 meter from windows located directly above the pipe.
From neighboring houses, at least 2 meters.
Directly at the exit from the building there should be no trees, walls, pillars, etc.
When installing such boilers, it is not allowed to combine them for two different systems heating, that is, natural draft and forced, in this case it is prohibited to combine.

It is possible to conduct the channel even through an adjacent room, but it must be taken into account that the horizontal length of the coaxial chimney in this case should not exceed 3 meters (with natural draft). No more than 5 meters with forced draft.

Horizontal channel diagram

Install a coaxial chimney for a wall-mounted gas boiler in a “lying” position. There are some design features of a coaxial chimney:

Possibility of placing no more than 3 meters of horizontal section.
The number of knees should not exceed two.
The distance from the window is at least 600 mm.
The distance from the nozzle to the outlet channel is no more than 1 meter.

In addition, remember important aspects, do not use sealant for joining and sealing. To do this, use only special rubber gaskets. Also pay attention to the fact that it is prohibited to use homemade adapters to connect to the boiler. Elements of a coaxial chimney must comply with manufacturer standards.

Installation features

Gas boilers with a coaxial duct and chimney mean certain features installation, which we present below. So, coaxial chimney for a gas boiler, installation rules:

Do not use more than two folds.
In horizontal structures, the section of the outlet channel must necessarily have a downward slope of 3 degrees. If the horizontal section, on the contrary, enters the boiler, then the tilt is made in the opposite direction. This is required for good condensate drainage.
Installation of boilers where the installation of a coaxial chimney is provided does not require the presence of windows in the room.
Installation must be carried out in such a way that during subsequent repairs the relative position of the boiler and pipe does not change.
Condensate drain areas, elbows, and adapters must be accessible for inspection.
It is prohibited to install pipes below the potential ground level.
There must be at least 8 meters from the canal to the nearest wall of the adjacent building. In some cases, it is allowed to reduce the distance to 2 meters (if there is a deflector and the wall is blank) and to 5 meters, if there are openings.
If the head comes out at a height of less than 1.8 meters, according to the standards it is necessary to install a special grille that will protect from hot air.
Correct installation of a coaxial chimney includes requirements for installation of this type - pipes need to be inserted only in such a way that the previous one is inserted into the next section, and vice versa if the movement goes to the boiler.
If turbulence and strong wind currents often appear at the exit points, you need to install a special barrier. Its installation is meant to be at a distance of at least 40 from the outlet.

For each channel, the manufacturer always supplies individual instructions. Be sure to pay attention to this and, if possible, compare it with the current requirements of current SNiPs and rules. In case of disagreement, the strictest of them should be followed.

In conclusion, I would like to add that such chimneys do an excellent job of maintaining the atmosphere inside the room in ideal condition, without the penetration of exhaust gases, due to the closed combustion chamber. Every year, owners of country housing, which is just under construction or has been built for a long time, turn their attention to such systems as the most optimal and safe.

Increasingly, in the manufacture of a smoke exhaust system, a coaxial chimney for a gas boiler is used. Given that correct installation, the coaxial pipe copes with two tasks at once: it removes combustion products and provides sufficient air flow for the operation of heating equipment.

There are several types of chimneys, differing in material and design, as well as various technical characteristics.

Coaxial chimney - what is it

The coaxial chimney is simple design. Basically it's just two pipes different diameters, inserted one into the other, so that between the walls of the outer and internal contour there was a gap of several cm.

All pipes, regardless of the design features and the material used, can be divided into two groups:

Collective coaxial chimneys for gas boilers are manufactured exclusively in the factory and installed during the construction of the building. To increase traction characteristics, they have an internal layer of thermal insulation.
Individual systems – chimneys designed for household use and connections to one heating device. Plastic chimneys are mainly used for condensing boilers, due to their low cost. Double-channel stainless steel pipes are used much less frequently.

The effectiveness of the smoke exhaust system largely depends on the right choice pipes. First you need to learn about how a chimney works, as well as on which boilers you can install a coaxial pipe.

The principle of operation of a coaxial chimney

The coaxial pipe is designed for simultaneous removal of combustion products and air intake from the street. The gas circulation process is carried out through two channels.

The principle of operation of the chimney is as follows:

For effective operation of the pipe, you will need to: strictly comply with SNiP for coaxial chimneys, carry out a preliminary calculation of the system, and also perform correct assembly, including the installation of safety components: a condensate collector, an anti-icing nozzle, etc.

On which boilers can a coaxial pipe be installed?

Coaxial type chimneys are designed for connection to condensing and turbocharged boilers with closed chamber combustion, with forced or natural system smoke removal

The pipe is optimally suited for parapet units and convectors. It is possible to install a coaxial system on a boiler with an atmospheric burner if the pipes are made of stainless steel.

The simple design significantly increases the operating efficiency of gas equipment. Almost everything modern models connect to two-channel systems. The installation of steel coaxial chimneys for single-circuit and double-circuit gas boilers is permitted, regardless of the operating principle and design of the combustion chamber.

To determine whether it is possible to install a two-channel chimney, you should be guided by the parameters specified by the manufacturer in technical documentation. Typically, it contains detailed instructions and standards, as well as requirements for installing a smoke exhaust system.

Some models of condensing turbocharged boilers have separate system removal of combustion products through two separate outlets. One for removing combustion products, the other for air intake. In such modifications the connection coaxial pipe not advisable.

Types of coaxial smoke exhaust pipes

When choosing a coaxial pipe for gas equipment, you should remember that for some brands of boilers only branded chimneys manufactured by the same company as the unit itself are suitable. , – all these manufacturing companies manufacture equipment with non-standard sizes of outlet pipes. Therefore, the use of branded components is considered optimal for the manufacture of a smoke exhaust system.

In all other cases, the choice mainly comes down to selection suitable material pipes. The design of the systems is made of aluminum, of stainless steel and plastic. In domestic conditions, plastic pipes and stainless steel products remain the most in demand.

Double-channel plastic chimneys

Plastic chimneys are made of special heat-resistant material that can withstand maximum heating temperatures of up to 205°C. Pipes are connected to condensing equipment gas type. Advantages of plastic:

Light weight.
Low cost.
Easy installation.

The disadvantages include the relatively short service life of coaxial chimneys made of plastic, as well as limitations associated with the ability to connect to conventional gas boilers. The system may only be used in low-temperature gas exhaust conditions.

Stainless steel coaxial pipes

The stainless steel used in the manufacture of the chimney is acid-resistant and can withstand more than plastic pipe temperature, up to 550°C. Manufacturers offer chimneys of two designs:

When choosing a coaxial pipe, they are primarily guided by the recommendations of heating equipment manufacturers specified in the technical documentation.

Regulatory requirements for installing a coaxial chimney

State standards and rules for installing a coaxial chimney for a gas heating boiler with a closed combustion chamber are set out in. Design, calculation and installation work is carried out in accordance with regulatory documents. Failure to comply with the recommendations leads to a refusal by the Gas Service to commission the heating system.

The standards regulate the distance from the coaxial chimney to the window, doorways, nearby buildings. Indicated minimum requirements, related to the production of fireproof cuts and other safety standards. In particular, SNiP stipulates:

The location of the coaxial chimney on the facade - the head is placed no lower than two meters from the ground level. The size of the hole in the wall should exceed the diameter of the coaxial pipe by 1 cm, in the case of a brick wall, by 5 cm for a wooden wall.
The use of coaxial chimneys in multi-storey residential buildings - standards allow the installation of pipes of this type, subject to following conditions. The minimum distance to window and door openings located on the same level is at least 0.5 m. To a window located above the chimney is at least 1 m.
Danger of poisoning from combustion products discharged through the coaxial pipe, if used condensing boiler, absent. Provided the system is installed correctly, the impact of exhaust flue gases on residents of the upper floors is negligible. Violations during the installation process lead to condensation on neighbors' windows.
Fire regulations and safety requirements. The size of the gap between wooden wall and a coaxial chimney of 5 cm. The minimum gap is determined by the fact that during operation the surface of the outer contour of the pipe practically does not heat up. It is necessary to install non-combustible materials between the coaxial pipe and the wooden wall. It is optimal to use basalt insulation.
The regulated distance from the coaxial chimney, relative to the windows and doors of neighboring houses and other buildings, is at least 1.5 m. The area should not be blocked by walls, tree poles, etc. Discharge of combustion products from a condensing boiler into a conventional chimney, instead of a coaxial one, is prohibited.
A coaxial chimney can be either horizontal or vertical. Installation of a collective smoke exhaust system is carried out only after obtaining permission from the gas service. It is not allowed to connect boilers with forced and natural removal of combustion products to the same network.
Horizontal section - laying a two-channel chimney through an adjacent non-residential premises allowed only if the pipe length does not exceed 3 meters. In turbocharged models, with the presence of a function for forced removal of combustion products, it is allowed to increase the horizontal section to 5 m.
Restrictions on output through the facade. The prohibition against draining condensate onto the ground must be carefully observed. The pipe is installed at an angle to the boiler. If there is a condensate drain, it is possible to slope the outlet pipe towards the ground to drain rainwater. When connecting collectively, you will need to coordinate the disposal of accumulated condensate with the sanitary and epidemiological authorities.
Installation standards - the coaxial chimney must protrude from the wall at a distance of at least 30 cm. For turbocharged boilers, with a chimney section of about 1 m, a narrowing diaphragm must be installed - a unit that compensates for the insufficient length of the chimney. A diaphragm in a coaxial chimney is needed to limit the flow of air into a closed combustion chamber. Turbocharged boilers are designed to use a chimney 5 m long. The diaphragm eliminates the difference.
Coaxial pipe maintenance - the system is serviced annually, at the beginning and end of the heating season. The accumulated condensate is removed, the tightness of the joints and the absence of burnout in the structure are checked.

Requirements regarding the safe operation of coaxial chimney systems may change, therefore, before purchasing and installing, you should consult a specialist.

Mounting options

Complete with a coaxial chimney, factory assembled, required detailed instructions on installation. Following and carefully implementing these recommendations is reflected in the operation of the boiler and the efficiency of the smoke exhaust system. According to experts, main reason blowing out of the boiler, the appearance of frost or ice, is associated with errors in calculations and when connecting the chimney.

Horizontal installation of coaxial pipes

Horizontal installation is carried out taking into account the technical characteristics of the building. Initially, the location where the pipe exits the wall is selected. There are restrictions related to the distance to the nearest neighbor's window when removing a horizontal coaxial chimney from the wall, which must be carefully observed.

Additionally, the following parameters are calculated:

The height of the pipe is from the boiler outlet to the passage hole in the wall; for floor-standing gas boilers, the height must be at least 1 m. Direct pipe outlet from the outlet to the street is not allowed. For wall-mounted gas boilers, the height can be reduced to 0.5 m.
The number of rotary couplings on the site should not exceed 2 pieces.
The maximum length of the horizontal section is 3-5 m, depending on the boiler model. To extend the pipe, a coupling with heat-resistant sealing rubber bands is used. The use of silicones and sealants is prohibited.

A peculiarity of using a two-channel chimney in winter is the increased production of condensate. The reason for moisture loss is that the system was originally designed for more favorable operating conditions. If the formation of condensate increases, the pipe will need to be insulated.

Vertical installation of a two-channel pipe

Vertical installation of the chimney provides two connection methods:

How to properly install a coaxial chimney pipe

Exist general rules and standards that help install the chimney pipe in such a way as to avoid further operational problems. The recommendations specifically stipulate:

System output through the wall.
Connection to the boiler.
Possibility of extending the two-channel system.
Protection against icing and wind.

Coaxial type chimney outlet through the wall

Installing a coaxial smoke exhaust system through a wall is actually quite simple. The difficulty lies in the definition optimal location, to complete this task. Fire safety requirements are imposed on the location of the coaxial chimney. Some standards are described in SP 60.13330.

The recommended tilt angle of the horizontal section is 3° towards the heater. If a condensate drain is installed, it is possible to slope in the other direction.
The maximum length of the horizontal section of the coaxial pipe is from 3 to 5 m, depending on the technical parameters of the installed boiler. No more than two corners may be used along the entire length of the chimney.
The passage through the brick wall is made with a gap of 1 cm. The gap is not sealed non-flammable material and is closed with a special cover.
The passage through a wooden wall expands by 5 cm compared to the diameter of the pipe. Basalt insulation is placed into the resulting gap. Alternatively, seal the hole around the coaxial chimney in wooden wall at home, you can use special fireproof polyurethane foam.
A tee with a condensate collector and an inspection channel for cleaning is installed.
The concentration of exhaust gases when connecting a coaxial chimney is low. But for safety reasons, it is recommended that minimum distance the exit of the coaxial chimney above ground level was no lower than 2 meters from the ground. Thus, the minor danger of gas combustion products can be completely eliminated.

Installation work is carried out in accordance with the instructions provided by the manufacturer.

How to connect a two-channel chimney to a boiler

One of the common mistakes when connecting a coaxial smoke removal system is the use of improvised means, which is a gross violation of safety and operational regulations. The standards require the use of a special adapter for connection. It is prohibited to install a self-made pipe from a piece of stainless pipe.

Immediately after the outlet pipe, install a tee with a condensate collector, after which the pipe is raised up 0.5-1 m, an angle is set and the chimney is brought out through the wall. Before commissioning, check the quality of traction.

How to lengthen a coaxial pipe

It is not always possible to install the boiler in such a way that the chimney is no more than 1 m. In some cases, it will be necessary to increase the length of the pipe. The structure is assembled according to the “father-mother” principle. Pipes are installed over condensate. For corners, 45° and 90° rotary couplings are used.

It is prohibited to seal joints with silicone. The adapters are equipped with rubber seals that can withstand heating up to 250°C. During installation, it is necessary to reduce the number of turns and angles as much as possible to ensure better traction. Mounting clamps are installed along the entire length.

How to protect a coaxial gas exhaust system from icing

Icicles on the head indicate obvious violations during installation work. As a general rule, if the design calculations and subsequent installation are carried out correctly, there is no risk of icing.

You can additionally protect the chimney from ice formation as follows:

An anti-icing nozzle is a unit that helps eliminate the problem of pipe freezing, even if installed incorrectly.
If the pipe design does not have a condensate drain, the slope should be made towards the boiler, which will lead to condensate draining into the tee and a special collection tank. When, despite observing the slopes, frost still forms on the head, this indicates incorrect calculations. If a condensate drain is installed, you will need to protect the brick from gas combustion products by extending the pipe head 50-60 cm from the wall.

When using individual coaxial chimneys in low-rise residential construction, installation of an anti-icing nozzle is mandatory.

The maximum boiler power allowed for connection to a coaxial chimney is 40 kW. Installation of equipment, with large parameters performance, leads to insufficient draft, increased condensation production and icing.

How to protect a two-channel chimney from the wind

Blowing out the boiler and the presence of reverse draft is unacceptable. If you do not protect the system from wind and draft, combustion products will enter the room, which often leads to carbon monoxide poisoning of residents.

You can avoid backdraft as follows:

Installation of wind protection and diaphragm.
Correct placement of the pipe under the window, relative to doorways and surrounding buildings.

The distance from the window on the outside of the wall is at least 1 m. If the chimney is placed closer, a draft will form when the window opening is opened.

Pros and cons of coaxial smoke removal systems

Every smoke exhaust system, without exception, has certain advantages and disadvantages. When deciding whether the use of a coaxial pipe is justified, you should pay attention to several important factors:

Cost of design and installation.
Advantages and disadvantages.
Boiler type.

Cost of a coaxial chimney kit

Compared to a conventional chimney, a coaxial chimney is more expensive. A standard meter set will cost approximately 3,000 rubles. Each additional meter for extension costs another 1800-2000 rubles. Knee and sealing rubber at 1500 and 300 rubles. respectively.

In general, assembling the system, provided that the connection is carried out independently, will cost from 6 to 10 thousand rubles. Pleasure is not cheap. For some types of gas equipment, there is no alternative to installing a coaxial pipe. For example, it is prohibited to use a conventional chimney for a condensing heating boiler.

Some, wanting to reduce the cost of the smoke exhaust system, use improvised means. On the Internet you can find videos and articles about how sewer pipes are used as a chimney for a condensing boiler, which is dangerous and leads to carbon monoxide poisoning of the residents of the house.

It is better not to skimp on safety and buy the chimney pipe that the heating equipment manufacturer recommends installing.

Advantages of a chimney made of coaxial pipes

The main advantage of a coaxial smoke exhaust system is that during the operation of a gas boiler, air taken not from the room, but from the street, is burned. As a result, the requirements for room ventilation are reduced and total area room used as a boiler room.

Existing standards allow the boiler to be installed in an unventilated room, since the need for ventilation in the boiler room is minimal. If we compare, a boiler with a closed combustion chamber uses the same amount of oxygen from the room during operation as is necessary to burn one burner of a gas stove.

The main advantages of a coaxial pipe over a conventional chimney are as follows:

Installation speed.
Can be used for almost any heating equipment.
Provided that it is installed correctly, good performance traction characteristics.
Possibility of application for apartment buildings.

Given the advantages of two-channel designs, it is not surprising that such systems have become widespread.

Disadvantages of two-channel pipes

Double-channel pipes have their disadvantages:

Coordination with sanitary and epidemiological supervision is required. During operation it is released a large number of toxic condensate. It is prohibited to pour it into the ground. Disposal is allowed in specially designated areas.
In practice, if you install a two-channel design in a private house, then all possible complaints will be reduced to the wishes of the owners of the house, from representatives of the gas service, to dispose of condensate in the correct way. For collective systems, you will have to obtain permission from the sanitary and epidemiological inspectorate.
Large amount of condensation. No matter how you insulate a two-channel pipe, the amount of condensate produced will still be large. Even minor violations during installation lead to icing of the outlet, decreased traction characteristics, etc. When installing a coaxial chimney, you will need to insulate the pipe from condensation.

Typical errors during installation and operation

The main mistake still remains connecting the pipe independently by a person who does not have special skills. The main recommendation of installation specialists is to invite licensed workers to carry out the work, capable of performing calculations and installing the structure without violations.

As practice shows, certain violations occur more often than others:

Incorrect calculation of the system - there is a direct dependence of the outlet temperature on the length of the pipe. Exceeding the maximum distances leads to cooling of the escaping smoke so much that it is not able to heat the accumulating condensate. As a result, icicles form on the head.
Failure to comply with fire safety regulations. Length of horizontal pipe section outside wooden building increases to 60 cm. Fire clearances must be made.

As a separate point, we can highlight the absence of protective units and elements, which slightly increase the cost of the structure, but increase the efficiency of the smoke exhaust system.

Required components vertical system is a kit for draining condensate, as well as a valve to increase draft. Horizontal structures wind protection, a diaphragm, and an anti-icing module are required.

Correct calculation and qualified performance of work, in accordance with existing SNiP and SP, guarantees effective work coaxial chimney throughout its entire service life.

The onset of winter always raises the question of the need for proper organization of the heating system.

Everyone needs to warm up; no one wants to live in a cold apartment and freeze. And they heat rooms most efficiently gas boilers. They heat up quickly, hold the temperature well, and the cost of operating such equipment will probably be affordable for everyone.

Let's not forget about the functionality of boilers. Good unit It is capable of not only heating the room itself, its power is also enough to heat water for domestic needs. But here another question comes to the fore - how to remove combustion products from the boiler to the outside of the building and do this as efficiently as possible? Now you'll find out.

Contents of the article

Problems with standard chimneys

A gas boiler has many advantages compared to the same electrical appliances. But there are also disadvantages. The disadvantages primarily relate to the removal of combustion products from the boiler.

Be that as it may, electricity does not leave waste behind, but after the operation of a gas boiler, a large amount of carbon dioxide and carbon monoxide is formed, which must be removed in a timely manner.

To eliminate carbon waste they use. Chimneys are different. Meet the usual steel pipes, ceramic, brick pipes, etc. Their installation and features depend on the specific variety, type of house, location of outlet and many other things.

However, conventional chimneys also have their disadvantages. They are quickly forgotten, and the draft inside the boiler decreases. If cleaning is not done in a timely manner, the problem only gets worse.

The chimney may become clogged, completely blocking the operation of the gas boiler. As a result, it either will not function or will emit combustion products inside the room, which is also, of course, unacceptable.

Plus an ordinary chimney, although an effective thing, has its own design flaws. For example, the smoke exit and air supply go through the same pipe. In most cases there is no problem here, but there are exceptions.

For example, if the chimney is even slightly clogged, then the flow of incoming air will greatly decrease, which will immediately affect the draft inside the gas boiler, and this will accordingly reduce its efficiency. You will have to burn more fuel to get the same result. Not the most pleasant action, is it?

Product Description

However, such situations can be circumvented. Modern technology has long learned to create truly effective designs, freed from the problems of the past.

A coaxial pipe is just one of these structures. A coaxial pipe is a pipe that consists of two main parts. Two shells that function in pairs.

The inner shell of the pipe has a smaller diameter. Its standard size is approximately 60 mm. A pipe with a diameter of 60 mm is considered the basic one, but other, larger samples are also found.

Pipes smaller than 60 mm are not suitable for coaxial chimneys; their cross-section is too small to remove smoke and combustion products outside in sufficient quantities.

Also, when interacting with a pipe less than 60 mm in diameter, the chance of it becoming clogged with sediment increases greatly, although it is significantly reduced for coaxial products compared to conventional chimneys.

The second pipe will be larger. Its diameter is approximately 100 mm, provided that the inner one has a diameter of 60 mm. That is, the size ratio is at the level of 1 to 1.5.

The purpose of a pipe with a diameter of 100 mm is to organize a constant flow of fresh air to the boiler. It also drains condensate, which accumulates on the outer walls of the inner pipe. It is worth understanding that a 100/60 mm pipe is only one of the options, and there are a great many of them.

The pipes are attached to each other using clamps and various types of supports. Due to their design, they do not touch each other, which is very important.

Actually, such a solution is called coaxial because of the two-axis structural mechanism embedded inside.

Advantages and disadvantages

The use of coaxial pipes together with the design of gas boilers gives an amazing result. This design has more than enough advantages.

Let's list the main ones:

increasing the efficiency of heating equipment;
safe and continuous removal of carbon monoxide, reducing the likelihood of clogging the chimney pipe with reverse draft;
constant condensate removal and fresh air supply through insulated pipe with a diameter of 100 mm or more;
reducing the likelihood of breakdowns;
simple and at the same time very effective design (installation is carried out according to a pre-designed scheme).

As you can see, this solution provides a lot of positive results. The efficiency of a gas boiler increases due to several factors. Primarily due to the constant and continuous flow of air through an external pipe with a diameter of 100 mm.

Condensation also accumulates in it; it does not have access to the insides of the smaller part of the chimney with a diameter of 60 mm. This brings up another important advantage.

Cleaning coaxial chimneys is greatly simplified in terms of the application of physical effort, since condensate with oxidation inside often causes the formation of solid deposits on its walls.

At the same time, the condensate dries out on its own, due to the same reverse draft. Moreover, this process occurs quickly, without unnecessary costs.

Accordingly, thoughtful design has a positive effect on all aspects of the heating equipment.

Do coaxial designs have any disadvantages? Of course have. All equipment without exception has them.

Main disadvantages:

increased price;
pipes are strictly typed and standardized, developers customize them for specific tasks, which complicates the modification process;
more difficult to do on your own;
installation involves following safety measures and special requirements that cannot always be met.

Installation of equipment

As we noted above, the installation and installation of coaxial pipes for a gas boiler differs from what we are used to seeing. The special design of coaxial outlets adds requirements that seriously complicate installation.

Now you need to think not only about how to lay a pipe according to the simplest scheme. And this is not so easy, especially if the withdrawal is supposed to be organized from an apartment in an apartment building.

It is also necessary to comply with all requirements, ignoring which is fraught with serious complications in the future.

Primary requirements

Before we consider the entire installation from start to finish, let’s turn to these same requirements. They are very important and for good reason.

Basic requirements for the installation of coaxial pipes with dimensions of 100/60 mm:

the pipe is installed so that it is suspended with a slope of approximately 3 degrees;
The outlet of a coaxial chimney cannot be installed closer than 1.5 meters from the ground and 0.6 meters from the window;
Installation of all components (and the coaxial chimney is completely collapsible) is carried out only using. No initiative, otherwise there will be trouble;
If the pipe needs to be lengthened or further stretched, we use sealants and mastics for coaxial leads. It is better to buy them from manufacturers; they often provide their customers not only with direct products, but also with all the materials necessary to service them.

All these requirements must be strictly observed. This is especially true for points that are responsible for the direct location of pipes.

Installation at an angle of 3 degrees is necessary for safe and continuous removal of condensate from the pipe. If the angle is broken, condensation will flow slowly and stop drying, and this is fraught with serious problems.

Installation process

Let's look at the installation of a pipe using the example of installation under a Baxi boiler. In fact, you can choose any boiler; they almost always have an identical design.

As a working coaxial chimney, we will take the most common option in our area, a 100/60 mm pipe. Where 100 mm is the diameter of the outer pipe for generating draft, and 60 mm is the diameter of the inner pipe that directly removes combustion products.

Stages of work:

We are preparing all the equipment.
We are planning the route for laying the pipes.
We drill holes in the structures that interfere with us. We select the diameter according to the outer chimney pipe, adding another 10 mm to it for fasteners. If our pipe has a diameter of 100 mm, then the hole must be drilled with a diameter of 110-115 mm.
We connect the base to the output from the boiler. Most often, this pin is located on its top panel.
We install the first part of the pipe, secure it with fittings.
We continue to lay the coaxial chimney in compliance with all requirements.
We seal pipe joints.
We test the operation of the system.

As you can see, there is nothing complicated in this process.

Installation of a coaxial chimney (video)

Try to fasten all parts of the pipes as best as possible. The better the quality of the joints, the fewer problems there will be in the future.

If necessary, add fittings to the structure, but only where they are really needed. For every three meters of pipe, a maximum of 3 fittings or two elbows are allowed. But this is a boundary line mark. It is advisable to reduce their number to a minimum.

Make sure that the axes of the outer and inner pipes are parallel to each other and never move. Displacement, of course, can happen, but only over time. During the installation process, everything must be perfect.

One of the most effective means for heating a home is a heating system connected to a gas boiler. Boilers using gas as fuel warm up quickly enough and maintain good temperature regime and inexpensive to operate. In addition, a good gas boiler often also provides water heating, which is very convenient and profitable.

An important component heating system The pipe that allows the boiler to operate is a pipe that discharges combustion products into the atmosphere. The removal of combustion products can be carried out by coaxial pipes for gas boilers, which will be discussed in this article.

Problems with conventional chimneys

As mentioned above, one of the main problems that arise when using gas heating equipment is the removal of combustion products from the system. This is a serious drawback, and most other heat sources do not have this quality - but here you have to take care of removing carbon dioxide and carbon monoxide.

To remove these substances, chimneys are used, which may have different designs and be created from different materials - metal, ceramics, brick and many others. The installation and characteristics of a chimney directly depend on its purpose, design features and other parameters.

All chimneys that fit this description, in addition to their advantages, also have a lot of disadvantages. Firstly, it is worth noting the problem associated with the exhaust and supply of air through one pipe - sometimes this leads to deterioration in the operation of the system. However, this problem seems insignificant compared to the next one.

Secondly, any chimney becomes clogged over time, as a result of which the draft in the boiler becomes much worse. If you leave a clogged chimney for a gas water heater in an apartment without attention, then at some point it will become completely clogged and the heating system will stop working. In addition to stopping the heating, a clogged chimney also threatens that gas combustion products will enter the living space - and this should not be allowed under any circumstances.

Installing a coaxial pipe for a gas boiler as a solution

The problems described above are quite unpleasant, but technology does not stand still, and the construction sector was no exception - coaxial pipes began to be used as chimneys. A coaxial pipe is a structure that includes two pipes, one of which is located outside, and the second, respectively, inside.

The inner tube has a smaller diameter - the standard value is usually about 60 mm. However, sometimes a larger diameter of the coaxial pipe for a gas boiler is selected. It will not be possible to use a pipe with a diameter of less than 60 mm as a chimney - such a cross-section is not enough to effectively remove combustion products. In addition, the small diameter of the chimney often causes complete clogging with various deposits, even taking into account the low susceptibility of the coaxial pipe to this factor.

The outer pipe has a larger diameter - the average value for a 60 mm inner pipe is 100 mm. Simple calculations allow us to say that the dimensions of the pipes are in a ratio of 1:1.5. A pipe with a diameter of 100 mm ensures a continuous supply of air to the boiler. In addition, the outer shell is necessary to drain condensate that is released on the inner pipe.

Regardless of the selected sizes of coaxial pipes (and their configuration may differ significantly from standard values), installation of the coaxial pipe of a double-circuit gas boiler is carried out using clamps and special fasteners. During installation, it is necessary to ensure that there is no direct contact between the two pipes - in fact, the coaxial nature of the structure implies the presence of a biaxial mechanism.

Advantages and disadvantages of such a solution

Coaxial pipes in combination with gas heating equipment ensure high-quality operation of the entire system. This is largely due to the positive qualities inherent in the type of chimney in question.

The main advantages of coaxial pipes are as follows:

Significant increase in the efficiency of the heating system;
Safe and permanent removal of combustion products;
Good protection of the structure from clogging;
Condensate is removed from the system through a safe circuit, and air enters the system through a separate pipe;
Low probability of problems occurring;
Simplicity of design with high efficiency.

All these advantages together seriously increase the efficiency of the system as a whole. For example, a constant supply of fresh air through an external pipe provides the system with the oxygen necessary for combustion. Condensation is also retained on the outer pipe and gradually dries, so the inside of the system is protected.

The condensate aspect is very important - most of the internal damage to the system is caused by it. As a result of the release of condensate and the accompanying oxidation processes, solid deposits appear on the surface of the pipe, which subsequently must be cleaned. The use of a coaxial pipe with its special characteristics makes cleaning the structure much easier.

However, coaxial pipes also have several disadvantages, including:

High cost of materials;
Standardization of pipes does not allow the creation of individual configurations;
Installing a coaxial chimney is very difficult to do on your own;
During installation, it is necessary to comply with a number of safety requirements, which is not always possible to do.

Requirements for installation of coaxial pipes

To realize all the positive qualities of a coaxial chimney, the following requirements must be met:

The slope of the pipe from the axis should be about 3 degrees. This requirement will allow the system to independently remove condensate from the pipe. Otherwise, moisture removal will occur too slowly, resulting in the system becoming clogged and unable to perform its functions.
The pipe outlet should be located at a height of 1.5 meters from the ground and at a distance of 0.6 m from the nearest window.
During installation individual elements designs, it is necessary to use fittings, avoiding various handicraft methods of connecting pipes. In addition, it is undesirable to bend the pipe more than three times - an excessive number of turns reduces the strength of the structure.
The length of the coaxial pipe for a gas boiler can only be increased with the help of special sealants or mastics purchased from pipe manufacturers. Inappropriate materials may cause damage to the integrity of the chimney.

Installation of a coaxial pipe of a gas boiler, carried out in compliance with these requirements, will allow you to assemble a reliable and high-quality structure.

Installation of coaxial pipe

Installing a coaxial pipe for a gas boiler falls into the category of complex processes - the design is not simple, and the requirements for it are quite serious. In addition, you need to think in advance about how to install the pipe according to the simplest possible scheme, so as not to complicate the already problematic installation.

The process of installing pipes for different boilers is practically the same. For example, you can take a standard chimney, which includes pipes with a diameter of 100 and 60 mm (external and internal pipes, respectively).

The installation algorithm for coaxial pipes is as follows:

First you need to prepare all the equipment and design the future structure.
In all ceilings and obstacles through which the pipe will pass, it is necessary to drill holes, the size of which should be 10 mm larger than the diameter of the outer pipe. A 10mm tolerance is required to install the fasteners.
The base is connected to the boiler outlet. Most boilers have the outlet on the top, so there shouldn't be any problems.
Next is installed Bottom part pipes. Its fixation is carried out using clamps and fittings.
After installing the first section, you can begin installing the remaining elements of the coaxial chimney.
The pipe connections must be treated with sealant or similar material.
The last stage is to check the system for functionality, for which you need to conduct a test run.

The pipes must be connected tightly and efficiently - its operation depends on how well the sections of the chimney are joined. The outer and inner pipes must be located on the same vertical axis and strictly parallel to each other - any contacts are unacceptable. As practice shows, a small displacement occurs during operation, but it is insignificant and does not affect the performance of the system.

It is best to keep the number of fittings and elbows to a minimum. According to the requirements, 3 fittings or 2 elbows can be installed on a three-meter piece of pipe, but this is the maximum permissible quantity - the smaller it will be various connections, the more reliable the design will be.

Conclusion

Installing a coaxial pipe for a gas boiler is quite complicated, but in the future it pays off in the efficiency of the heating equipment. When designing and installing, it is necessary to take into account all the nuances and approach the work with all care in order to create the most reliable and high-quality design.

Simply put, the chimney is inserted into the supply valve pipe. As a result, air is sucked into the combustion chamber through the gap between the pipes, and carbon monoxide, water vapor and other components of the boiler exhaust are discharged through the internal channel.

Both horizontal and vertical coaxial chimneys are designed in a similar way. After all, the orientation of the central axis of the supply and ventilation air duct does not affect the design features of such chimneys.

Through the coaxial air duct, both the gas or liquid fuel combustion chamber is ventilated and air flows to the burner. Wherein ventilation duct is installed inside the supply air duct.

Coaxial chimney delivery set

As a rule, coaxial systems for removing combustion products are included in the delivery package of gas boilers, as well as heating devices operating on liquid fuel. But if the consumer is not satisfied with the standard system, then he can purchase a coaxial chimney kit from a third-party manufacturer. However, such a kit must necessarily include the following components:

Elbow – a fitting for connecting the air duct and the boiler.
Coaxial air duct is a channel for pumping air into the firebox, inside of which there is an insulated pipeline that removes combustion products.
Chimney adapter - a fitting for arranging the point of passage of a coaxial air duct through a wall.
Clamps and flanges - fittings for connection components chimney.
Overlays are washers for decorating the point where the chimney passes through the wall.

At the same time, most manufacturers of gas boilers categorically do not recommend using homemade coaxial systems to remove combustion products. After all, it is practically impossible to create a truly efficient coaxial chimney with your own hands - such a product simply cannot provide a uniform flow of air into the combustion chamber. In addition, “homemade” increases the risk of carbon monoxide poisoning by almost an order of magnitude.

Types of coaxial chimneys

Despite the general structural design and configuration, the range of coaxial chimneys can still be divided into three groups, using the structural materials from which air ducts and fittings are made as the basis for classification.

Such a scheme allows us to distinguish the following types of chimneys from the general range:

Galvanized steel kits are the cheapest option for a coaxial chimney. However, the service life of such a product is only 5-6 years. After which the structure loses its presentability (rusts), and then completely collapses.
Stainless steel set - this material guarantees both a long period of operation and preservation of the original exterior. At the same time, “stainless” chimneys are not very expensive. But in the case of collective or industrial use of the system, installation of a coaxial chimney made of stainless steel is not recommended - this material will not withstand the high concentration of chemically active components of the “exhaust” of the heating device.

Sets made of acid-resistant high-alloy steel - this material will withstand the highest concentration of chemically active combustion products. However, such chimneys are not cheap.

As a result, “galvanized” chimneys are suitable only for supporters of budget solutions, “stainless” kits will suit only owners of household boilers, and industrial and municipal heating systems will have to be equipped exclusively with high-alloy, acid-resistant air ducts and fittings.

If you purchased a “standard” coaxial chimney - installation requirements similar system, as well as the installation diagram for such a design, can be found in the documentation for the heating device. The “passport” of the boiler or hot water column will outline the installation procedure and indicate the installation dimensions - the distance to the boiler, the diameter of the passage through the wall, etc.

The buyer of an “outside” chimney will not receive such hints. However, the versatility of the design and standard scheme configuration allows you to formulate installation rules common to all coaxial chimneys. As a result, the installation diagram of a “standard” or “extraneous” boiler furnace “ventilation” system looks like this:

Before installing the coaxial chimney, secure it to supporting surface the heating device itself. Moreover wall-mounted boilers should be fixed at a distance of 50-60 centimeters from the ceiling. The distance from the boiler to the wall adjacent to the supporting surface cannot be less than 15 centimeters. Floor heating devices are installed on a podium, raised above the floor, since the vertical section of the coaxial air duct cannot be longer than 300 centimeters.

Next, you need to punch a hole in the wall to allow the chimney to exit outside the house. The ideal location for the hole is above the boiler, right in the supporting wall. However, a hole can also be punched in the adjacent wall, closest to the supporting surface. In this case, the distance from the edge of the hole to the zero point (to the ground) cannot be less than 200 centimeters. The diameter of the hole should be 2-3 centimeters larger than the outer diameter of the coaxial duct. At the end of this stage, an adapter is attached to the outside of the wall, fixing the horizontal section of the chimney.
Next, you need to insert a horizontal section of the chimney into the hole. Possible from the street side. Moreover, the distance from the end of the outer section of the chimney to the wall should not exceed 60 centimeters. At the final stage, decorative washers are placed on the chimney from the inside and outside.

The next step is the installation of the elbow, which is installed on the chimney fitting of the boiler. If the heating device is installed on the floor or slightly below a hole punched in the wall, then a vertical air duct will have to be installed on the chimney fitting and only then an elbow outlet, the axis of which should coincide with the center of the hole. In this case, it would be a good idea to slightly raise the elbow above the axis of the hole, ensuring a slope of the horizontal section for the condensate to drain from the air duct onto the street. As a result, the minimum distance from the horizontal section of the chimney to the boiler body cannot be less than 25 centimeters.

Finally, it is necessary to fix the vertical air duct or elbow to the boiler chimney fitting using a clamp. Next, we fix the horizontal section of the chimney with the same clamp and, sealing the point of passage of the air duct through the wall mineral wool or other non-flammable heat insulator, we attach decorative pads-washers to the adapter.

As you can see: the installation diagram is not particularly complicated. Moreover, this operation can be started by arranging the point of passage of the chimney through the wall, postponing the installation of the boiler until last. In this case, you will not have to buy additional coaxial air ducts - the boiler neck will simply be installed directly under the chimney elbow.