The coaxial chimney for a gas boiler is a new technical solution that has replaced standard options. It is used for heat generators with closed camera boiler combustion). Main feature and the great advantage of this chimney is that the combustion air into the boiler firebox comes not from the house, but from the street.

Purpose

Coaxial is designed to perform 2 functions at once:

• removal of combustion products outside;
• ensuring inflow fresh air necessary to maintain the gas combustion process in the chamber.

Boilers with a closed combustion chamber are usually equipped with a chimney, the length of which is usually no more than 2 m. It should be noted that most often the chimney is installed outside through a wall. A less common option is when it is brought outside through the ceiling and roof.

If the place in the wall where the chimney is supposed to go is located near a window, then it is best to place it just above the roof. However, in this case it is necessary to install the vertical part of the chimney.

Coaxial chimneys installed in vertical and horizontal positions. They differ only in the installation method, but their operating principle is the same.

Components

A coaxial chimney for a gas boiler consists of the following components:

• several straight pipes;
• tees;
• cleaning;
• condensate collector;
• upper tip of the chimney;
• knee (angle 90).

A chimney is formed from straight pipes. The purpose of the knee is to connect horizontal chimney with its vertical part, as well as a gas boiler.

If the chimney is located only in a horizontal position, its kit includes the following elements:

• straight pipes;
• knee (angle 90);
• chimney tip (side).

A coaxial chimney for a gas boiler, like all engineering systems, has its pros and cons.

Advantages of a coaxial chimney: customer reviews

• Oxygen to support the combustion process comes from the outside, and not from the room. This is the main advantage of a coaxial chimney. Its design includes two pipes, one of which serves as the outer shell and the other as the inner shell. Through a pipe with a smaller diameter, combustion products - exhaust gases - are removed, and air is supplied to the combustion chamber of the boiler through the outer pipe to support combustion.
• The design takes up quite a small amount of space, which allows you to significantly save space indoors.
• The chimney heats the incoming outside air with exhaust gases, which significantly increases the efficiency of the boiler.
• The system is fireproof. When withdrawing flue gases are cooled by air entering the combustion chamber of the heating unit, which reduces the risk of a possible fire. There is no need to additionally insulate the chimney using highly flammable materials.
• Easy to install.

A similar chimney system can be installed on the following types of boilers:

• on gas;
• solid fuel;
• on liquid fuel.

Disadvantages of coaxial chimneys

Freezing. According to user reviews, this is the most important and serious drawback installed chimney. Its first models that appeared on the markets were not designed for low temperatures operation (-15 - -30 °C), which can cause freezing of the structure and failure of the heating unit. The coaxial chimney for a gas boiler (photo presented in the article) was intended for countries with a milder climate.

But not all experts are so categorical. In their opinion, the main reason for the freezing of such a chimney is incorrect thermal engineering calculations. If the chimney is selected correctly, it will not freeze.

When installing a vertical coaxial chimney, there is a problem of condensate collection. Since this drawback is known to manufacturers, certain models are equipped with a condensate collector.

Carrying out installation work

When installing a coaxial chimney yourself, be sure to read the included manufacturer’s instructions and follow all recommendations:

• During installation, only those materials and components that have been tested by the state gas inspection should be used; It is strictly prohibited to make any changes to the design and configuration of the chimney.
• When carrying out work, using materials that do not belong to the chimney manufacturer is strictly prohibited. Everything you need additional components should only be purchased from a special service center.
• All parts of the chimney are connected and tested for flue gas leaks.
• The use of sealants and adhesives is prohibited.
• It is prohibited to join pipes within the thickness of a wall. The junction should be provided outside it.
• The installation of a horizontal coaxial chimney is carried out (unless there are other instructions from the boiler manufacturer): for condensing units 2-3° towards it, for classic version 2-3° from it, to remove condensate and prevent precipitation from entering the boiler.
• The length of this chimney depends on the model heating boiler, complexity of the chimney line.
• It is prohibited to install chimney outlet equipment below ground level into the window pit of a semi-basement building.
• It is important to remember that during the operation of the chimney, all responsibility for breakdowns and possible breakdowns rests with the installer.

Installation sequence

The chimney is attached to the boiler and ducted outside the room. It is best to remove all unnecessary and flammable items before work.

Installation of a coaxial chimney for a gas boiler begins with choosing a location for the heating unit and chimney. It is better to install a gas boiler together. The best option is when the chimney is located 1-1.5 m above the boiler. If necessary, the chimney can be lengthened, but taking into account that there are no more than 2 bends, and their total height does not exceed 3 m.

Now you can start drilling holes of the required diameter (within 11 - 12.5 cm).

The next stage of work is assembling the chimney of the required configuration. Clamps are used for all connections. The chimney that exits the room must have a slight slope to remove moisture (condensation).

That's it. All that remains is to put on decorative overlays for aesthetics.

How to make a choice?

When choosing, first of all, you should pay attention to the recommendations provided by the boiler manufacturer. In some cases, service centers do not accept equipment under warranty due to the installation of a coaxial chimney that is not recommended for this boiler.

The functions of a coaxial chimney include ensuring not only the removal of flue gases, but also the intake of oxygen from the outside; for this reason, the reliability of its operation is very important. We suggest considering proven foreign brands: Baxi, Vaillant, Viessmann, Navien.

Coaxial chimney Baxi

It is made of high-strength polymer material. The standard kit includes a chimney pipe 1 m long, a 90° elbow, a wind protection nozzle, and decorative rings. If necessary, you can purchase an extension cord. It should be taken into account that a coaxial chimney for a Baxi gas boiler, the length of which is up to 1 m, requires the installation of a narrowing diaphragm on the boiler air duct. This is necessary to compensate for draft, since the boiler fan power is designed for a certain length of the chimney (5 m). If there is no diaphragm, an excess amount of air will enter the combustion chamber, which will reduce the efficiency of the boiler. To avoid freezing, the coaxial pipe is installed so that its protrusion from the wall is no more than the length of the tip. When exceeds right size, in this case, the excess is cut off from the inside.

Coaxial chimney Vaillant

Coaxial chimney for Vaillant gas boiler is included in the kit heating unit of this company. Matching the size of the pipes is the key to successful and long-term operation boiler In addition, such chimneys can be purchased separately for boilers from other manufacturers.

Coaxial chimney Navien

The coaxial chimney for the Navien gas boiler from the Korean company has proven itself well in the heating equipment market. It is available for both wall-mounted and floor-standing boilers with a power of up to 75 kW. The price of the Navien coaxial chimney is lower than that of European competitors, but the quality of workmanship, judging by the reviews, is in no way inferior to them.

Coaxial chimney for Viessmann gas boiler

Its advantages:

• Natural heating of absorbed oxygen in winter period time.
• The cost of a chimney and its installation is much cheaper than other types.
• Chimney installation requires less time.

Coaxial chimney - new technical solution, which replaced standard chimneys. The peculiarity and great advantage of this device is that the oxygen for combustion in the boiler furnace is taken from the street, and not from the house.

Coaxial chimney designs

Chimneys are used for different types boilers:

• B - chimneys for boilers with an open combustion chamber;
• C - chimneys for boilers with a closed combustion chamber.

In high-rise buildings you can find a variant of a collective chimney, to which individual boilers are connected. This chimney goes to the roof

Coaxial chimneys are mounted in two positions:

• vertical;

• horizontal.

Only the installation method differs, but the principle of operation of the chimney is the same. Like everyone else engineering systems, it has both advantages and disadvantages. Let's look at them.

Advantages

Structurally, the chimney consists of two pipes, one acts as an outer shell, the other as an inner shell. Combustion products - exhaust gases - are discharged through a pipe of smaller diameter. Air enters the combustion chamber of the boiler through the outer pipe to maintain combustion. This system provides a compact and aesthetically pleasing appearance, takes up little space. The system ensures heating of the incoming outside air with exhaust gases, which increases the efficiency of the boiler.

Another important advantage of this system is its fire safety. When flue gases are removed, they are cooled by air that enters the combustion chamber of the heating unit, reducing the risk of fire to zero. Additional insulation of the chimney with highly flammable materials is not required.

A similar chimney system can be installed on various types boilers:

• on gas;
• liquid fuel;
• on solid fuel.

Disadvantages of a coaxial chimney

Freezing. This is probably the main and most serious drawback when installing a horizontal chimney.

The first models of coaxial chimneys that appeared on the Russian market were not designed for such low operating temperatures - -15 - -30°C. They are designed for countries with milder climates. As a consequence, there is the possibility of freezing of the chimney and failure of the heating unit.

Although not all experts are so categorical. In their opinion, main reason freezing of a coaxial chimney is due to incorrect thermal engineering calculations. In this case, the boiler efficiency depends on the supply air temperature. In pursuit of increasing efficiency, designers reduced the diameter of the exhaust pipe. In this case, the temperature of the flue gases drops below the dew point, which leads to an increase in condensation formed inside the exhaust pipe and freezing. To reduce the effect of this factor, it is necessary to increase the temperature of the flue gases by increasing the diameter of the pipe. A properly selected coaxial chimney should not freeze.

When installing a vertical coaxial chimney, we are faced with the problem of collecting condensate. Since the problem is known to all manufacturers, models of coaxial chimneys intended for vertical installation are equipped with a condensate collector.

Rules for installing a coaxial chimney for a gas boiler

When installing a coaxial chimney yourself, you must read the manufacturer's instructions. Be sure to follow the rules for installing a coaxial chimney.

• During installation, use only materials and components that have been tested by the state gas inspection; It is prohibited to make any changes to the configuration and design of the chimney.
• During installation, it is prohibited to use materials not from the chimney manufacturer; Purchase necessary additional components only from service centers.
• All parts of the chimney are firmly connected and tested for flue gas leaks.
• Use of sealants and adhesive compositions forbidden.
• It is forbidden to join pipes within the thickness of the wall; it is necessary to provide a joint location outside the wall.
• A horizontal coaxial chimney is installed (unless otherwise specified by the boiler manufacturer): for condensing boilers 2-3° towards the boiler, for classic 2-3° outwards, ensuring condensate drainage and preventing precipitation from entering the boiler.
• The length of the coaxial chimney depends on the boiler model, the complexity of the chimney route and ranges from 1 to 7 m (the maximum length for a straight installation for a boiler with an installed turbine with a power of more than 30 kW).
• It is prohibited to install a coaxial chimney outlet below ground level into a window pit in a semi-basement.
• Remember, the installer is responsible for breakdowns and accidents during the operation of the chimney.

Coaxial chimney installation diagram

The exit of a coaxial chimney through the enclosing structures must comply with a number of rules and requirements. Since type C boilers have a closed combustion chamber, they can be installed in all types of premises. Regardless of the presence of windows in the ventilation system and the volume of the room itself, several standards must be adhered to. The photo shows the requirements for installing a coaxial chimney in different versions:

• a- minimum distance from the axis of the chimney to any opening element of the facade of the house;
• b - the minimum distance from the axis of the chimney to any air intake;
• c - minimum distance to sidewalks (to reduce the distance, install a grill with a deflector, in this case the distance will be 0.15 m);
• d - minimum distance from the ground;
• e - the minimum distance from the axis of the chimney to the wall at an angle of 90° with opening elements or air intake openings; (0.15 m with a deflector);
• f - the minimum distance from the axis of the chimney to the wall at an angle of 90° without opening elements;
• g - minimum distance to green spaces;
• h is the minimum distance to the drainage system or vertical pipeline.

Choosing a coaxial chimney

When choosing a coaxial chimney, first of all you need to pay attention to the recommendations of the boiler manufacturer. There have been cases when service center did not accept the equipment for warranty through the installation of a coaxial chimney, which was not recommended for this boiler.

A coaxial chimney must ensure not only the removal of flue gases, but also completely ensure the intake of oxygen from the street, so the reliability of its operation is very important. It is worth choosing from proven foreign brands: Baxi, Vaillant, Navien, Ferroli, Ariston, Viessmann.

Coaxial chimney Baxi

Chimneys are made from stainless steel and high strength polymer materials. The standard kit includes a 1 meter long chimney pipe, a 90° elbow, a wind protection nozzle, and decorative rings. If it is necessary to use an extension cord, it must be purchased separately. It should be noted that for a chimney up to 1 m long it is necessary to install a narrowing diaphragm on the boiler air duct. The procedure is carried out to compensate for draft, since the boiler fan is designed to maximum length chimney (5m), and in the absence of a diaphragm, a large amount of air will enter the combustion chamber, which will lead to a decrease in the efficiency of the boiler. To protect against freezing, the coaxial pipe should protrude from the wall to the length of the tip, no more. If the length of the pipe is longer than necessary, the excess is cut off from the inside.

Photos of the main Baxi coaxial chimneys:

Coaxial chimney Vaillant

Vaillant company completes boilers own production coaxial chimneys. Compliance with the size of the pipes is the key to successful operation of the boiler. Also, Vilent coaxial chimneys can be purchased for boilers from other manufacturers.

Coaxial chimney Navien

Navien smoke removal systems from the Korean company are well established in the heating equipment market. Chimneys are produced for wall-mounted and floor-standing boilers with a power of up to 75 kW. The cost of Navien coaxial chimneys is slightly lower than their European competitors, while the quality of workmanship is not inferior to them.

Any heating equipment: stove or heating boiler, fireplace or even simple geyser connected by a common feature: they need to utilize air, which is saturated with combustion products. This is not only a guarantee of comfort, but also safety. Failure to comply with chimney installation standards can even lead to dire consequences - carbon monoxide poisoning.

The latest solution for modern technologies heating is a coaxial chimney. It allows you to significantly reduce the volume of the chimney; moreover, during operation, air from the room is not used at all, which is undoubtedly an important advantage. This type of chimney is suitable for boilers with a built-in smoke exhauster (forced draft). It is much shorter and more compact than a regular traditional pipe. His European quality combined with an excellent price.

The principle of operation of a coaxial chimney

The smoke exhauster built into the boiler system allows air to be taken in from the outside through an external pipe at the same time as flue gases are removed through the internal pipe. Since air draft is practically guaranteed, the outer pipe has a small diameter and length corresponding to the installation layout. Exhaust air containing an admixture of combustion products is discharged from the boiler through an internal pipe. It is also shorter than the traditional one, and thus the boiler does not take up much space. The coaxial chimney is made from modern reliable acid-resistant materials, therefore inner tube does not react with harmful impurities, that is, it is not subject to destruction.

The structure of such a smoke exhaust is such that when exhausting, flue gases do not enter the air channel. All this must be taken into account when designing a coaxial chimney, installation standards and fire safety including. One more the most important condition Its reliable operation is ensured by the tightness of the connection of the external air channel and pipe.

SNiP for installation

Heating systems running on gas fuel are somewhat different from coal and wood stoves. Therefore, if a coaxial chimney is installed, the installation standards are also different.

In the case of chimneys of this type, combustion products can be discharged into the atmosphere through external wall premises. In this case, in particular, there is no need for a device vertical channel from the system through which combustion products will be forcibly removed. In this case, the opening of the smoke duct on the facade of the house is placed according to the installation instructions gas equipment from the manufacturer, but subject to the following conditions:

• at a distance of at least 2 meters from the ground level;
• the minimum horizontal distance to doors, windows and open ventilation grilles (openings) should be 0.5 meters;
• the minimum distance to the top edge of doors, windows and open ventilation grilles (openings) should also be 0.5 meters;
• the vertical distance from the windows located above the smoke duct opening is from 1 meter;
• in the area of ​​1.5 meters from the coaxial pipe there should be no obstacles, say, walls, pillars, etc.

The chimney pipe, if there is no condensate collector, must be installed at an angle to the ground, preventing condensate from flowing back. Optimal slope is 6–12°.

• If smoke channel placed under a balcony, canopy or roof eaves of a house, then it must extend beyond the circle with radius R. It is equal to the width of the part of the building protruding above the chimney.
• The smoke duct should not go through the external wall into passages (arches), underground passages, tunnels, etc.

When exiting through a wall, the length of the horizontal section of the channel is taken to be no more than 3 meters. However, manufacturing plants have different interpretations on this issue. For example, according to the instructions, the Ferroli coaxial chimney has a maximum permissible pipe length of 4 m (60/100) or 5 m (80/125), and the Navien coaxial chimney is 3 m. From all this we can conclude that, first of all, even before At the beginning of design, you must carefully study the instructions for the gas equipment that you intend to install, since for different boilers some of the basic parameters may not be the same.
(below are the SNIP documents and installation rules for chimneys of some manufacturers)

Coaxial chimneys from the best manufacturers are the key to reliability and quality

Coaxial chimney Ariston
Ariston chimneys made in Italy are suitable for most modern boilers. They also come with sealing gaskets and wall trims.

Coaxial chimney Baxi
The chimney in its design should have a length of up to 5 m. If it is directed towards the street, it is given a slope at the rate of 1 cm for each meter of its length. For Russian climate conditions, insulated options with the following changes made to the design are more suitable:

• head lengthened
• the design of the air intake duct is especially protected,
• made of composite material.

Such a system makes it possible to prevent icing of the chimney and cause the boiler to stop in emergency mode if the outside temperature drops to -50 C.

Coaxial chimney Proterm
These products are very easy to install and help increase the efficiency of the corresponding Protherm boilers. In addition to them, the company also offers extensions for chimneys, adapters designed for separate smoke removal, and more.

Coaxial chimney Vaillant
This company is considered one of the leaders in the European market. Its products are in great demand in recent years. When choosing chimney It is especially important that its cross-section corresponds to the cross-section of the Vaillant boiler pipe. When installing, it is necessary to ensure a distance between the chimney and flammable structural elements at least 100 mm.

Viessmann coaxial chimney
In addition to the coaxial outlet (diameter 60/100, 90°), the kit usually includes: a coaxial pipe equipped with a tip (diameter 60/100, length 0.75 m) and wall linings. Its special design prevents the pipe from freezing in winter.

Increasingly, in the manufacture of a smoke exhaust system, a coaxial chimney for a gas boiler is used. If installed correctly, the coaxial pipe copes with two tasks at once: removes combustion products and provides sufficient air flow for operation 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. Essentially, these are just two pipes of different diameters, inserted into one another, so that there is a gap of several cm between the walls of the outer and inner contours.

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 are chimneys designed for domestic use and connected 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 find out 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 efficient operation of the pipe, you will need to: strictly observe SNiP for coaxial chimneys, carry out a preliminary calculation of the system, and also carry out correct assembly, including the installation of safety components: condensate collector, 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 that have a closed combustion chamber, 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 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 a separate system for removing combustion products through two separate outlets. One for removing combustion products, the other for air intake. In such modifications, connecting a coaxial pipe is 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 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, 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 from a 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:

1. Light weight.
2. Low cost.
3. Easy installation.

The disadvantages include the relatively short service life of coaxial plastic chimneys, 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 buildings residential buildings– standards allow the installation of pipes of this type, subject to the 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.
  There is no danger of poisoning from combustion products discharged through a coaxial pipe when using a condensing boiler. 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 5 cm. Minimum clearance is due to 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 is allowed only if the length of the pipe 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 heating season. The accumulated condensate is removed, the tightness of the joints and the absence of burnout in the structure are checked.

Requirements regarding safe operation 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, the main reason for the boiler to blow out, 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 technical characteristics buildings. 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.

Features of using a two-channel chimney in winter time– increased production of condensate. The reason for moisture loss is that the system was originally designed for more favorable conditions operation. 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

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

1. System output through the wall.
2. Connection to the boiler.
3. Possibility of extending the two-channel system.
4. 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.
• Node of passage through brick wall is done with a gap of 1 cm. The gap is not sealed with non-flammable material and is closed with a special lining.
• 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 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 to ensure safety, it is recommended that the minimum distance of the coaxial chimney outlet above ground level should be 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, the 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. Generally, 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. Installing equipment with high performance parameters leads to insufficient draft, increased condensate production and icing.

How to protect a two-channel chimney from the wind

Blowing out the boiler, availability reverse thrust 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:

1. Cost of design and installation.
2. Advantages and disadvantages.
3. 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. Every extra meter for lengthening, another 1800-2000 rubles. Elbow and sealing rubber - 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 to use sewer pipes 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 and the total area of ​​the room used for the boiler room are reduced.

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, a large amount of toxic condensate is released. 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 require wind protection, a diaphragm, and an anti-icing module.

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

Choosing the optimal chimney for a gas boiler is not an easy, but completely achievable task. After all, you want it to be an extremely simple design to install and operate, and even with high efficiency. The coaxial type meets all the requirements, the installation of which can become a bit of a “snag”. Do you agree?

We will help you understand quite complex issues. We provide site visitors with extensive information about the rules for constructing a coaxial chimney, about the selection and arrangement optimal option. Here you will find valuable advice for decorating sections of canals laid inside houses.

The article we have proposed describes in detail the standards for installing a coaxial chimney. Given useful diagrams for its proper assembly and installation. The information is confirmed and supplemented by photo collections and video tutorials.

In the family of devices for removing combustion products, the coaxial chimney stands apart. This modern design much more efficient and safer than a conventional chimney. This system is ideal for boilers with a closed combustion chamber.

To make a coaxial chimney, you need to take two pipes different diameters and place the narrow pipe inside the wide one. Still need to connect inner side wide pipe and outside narrow pipe with special jumpers so that the central axes of both pipes coincide. Well, the coaxial chimney is ready.

In practice, such a design is, of course, easier and more reliable to buy than to make. The cost of a coaxial chimney will be higher than the price of an ordinary stainless steel pipe, but the costs will be fully recouped.

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