The device, the principle of operation and installation of a coaxial chimney

An autonomous heating system, if it does not work on electricity, cannot do without a device that removes combustion products. If earlier it could only be a traditional chimney, now there are other options, more efficient and practical.

Installation of a coaxial chimney provides many advantages, in addition, it can be made in an already constructed building. What is so good coaxial type chimney? We'll figure out.

The content of the article:

  • Coaxial chimney: what is it
  • Types of coaxial type chimneys
    • External and internal systems
    • Not warmed and warmed devices
    • Horizontal or vertical output
    • Collective and individual designs
  • Why choose coaxial systems
  • How to choose device dimensions
  • Installation of chimney in the light of regulations
  • Some installation features
  • Coaxial chimney mounting technology
    • Installation of the internal system
    • Mounting external structure
  • Useful video on the topic

Coaxial chimney: what is it

In the technology, the concept of "coaxial" means the presence of two any objects arranged so that one is inside the other. Thus, the coaxial type chimney is a two-circuit design made of pipes of different diameters. Inside the larger element is a smaller part. The distance between them is strictly the same throughout the length of the structure, including all bends and knees.

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For this purpose, special jumpers are placed between the pipes. In the context of such a system looks like a pair of concentric rings. The channel for the removal of smoke is an inner, smaller pipe. Through the gap between the two parts inside the heater from the street enters the necessary oxygen to maintain combustion. Thus, the gases inside the system move in opposite directions.

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Advantages of coaxial type flues
A weighty advantage of coaxial chimneys is a significant reduction in channel volumes while maintaining the standard performance.
Constructive advantages of the smoke channel
Chimneys of coaxial construction do not trap air from the treated room for combustion, do not affect the formation of the microclimate in it
Tightness of connection of the air channel
One of the fundamental conditions for the normal operation of a coaxial chimney is tightness at the point of connection of the external part of the air duct and branch pipe
Laying a horizontal pipe section
The horizontal pipe section should not pass through the dwelling, its length should not exceed 3 m
Compliance with the manufacturer's recommendations in the installation
When installing a coaxial type chimney, you should strictly follow the recommendations given in the instructions given by the system manufacturer.
Permitted in the manufacture of chimney materials
In the manufacture of coaxial chimney devices it is allowed to use only materials of non-combustible category. The thickness of the inner tube is at least 1 mm
Scope of use of coaxial flues
Coaxial type chimneys are not allowed to be installed in apartment buildings; use only in private low-rise buildings is allowed.
Conditions for safe operation
To ensure safe operation, the external area must be removed from the window and door openings. at least 0.5 m. When used in conjunction with a gas boiler, the installation of a detector is recommended. gas pollution
Advantages of coaxial type flues
Advantages of coaxial type flues
Constructive advantages of the smoke channel
Constructive advantages of the smoke channel
Tightness of connection of the air channel
Tightness of connection of the air channel
Laying a horizontal pipe section
Laying a horizontal pipe section
Compliance with the manufacturer's recommendations in the installation
Compliance with the manufacturer's recommendations in the installation
Permitted in the manufacture of chimney materials
Permitted in the manufacture of chimney materials
Scope of use of coaxial flues
Scope of use of coaxial flues
Conditions for safe operation
Conditions for safe operation

The design features of the coaxial type chimney enable it to perform functions immediately. The device provides uninterrupted flow of air, which is necessary to maintain the combustion process. In addition, it successfully removes combustion products from the boiler. The length of the structure usually does not exceed two meters. Most often mounted systems are oriented horizontally, but there are also vertical variations.

Coaxial chimney
Coaxial chimney system called "pipe in the pipe." Combustion products are discharged from the boiler through the internal element, and air is supplied through the external element.

A coaxial type chimney is a system of modules, which makes it possible to manufacture chimneys of various configurations taking into account the architectural features of the building. All elements included in the system are standardized, which greatly simplifies their installation.

Coaxial chimney
Coaxial type chimney can be oriented horizontally or vertically. In practice, mixed structures with vertical and horizontal sections are more common.

The standard kit consists of several modules:

  • Straight pipes. From the straight pipe segments is formed the actual chimney.
  • Tee. It is mounted into the system only in case of using two or more boilers.
  • Connecting elements. These are the 90 ° and 45 ° elbows, couplings.
  • Condensate discharge device. Such a kit is necessarily provided for each vertically oriented section. It is equipped with a water valve, which prevents the decrease in pressure of the gas-air mixture in the chimney.
  • Elements with a revision hole. It is intended to inspect and clean the system.
  • Output and input nozzles. Supplied with caps, used to remove the products of combustion and clean air intake. The exit nozzle is always mounted at a distance from the place of air intake so that it does not mix with the exhaust gases.
  • Adapter. It is used to connect the system with the boiler.
  • Armature for fasteners. These include brackets, clamps and flanges.
  • Seals. Devices required to ensure the tightness of the passage of the pipe through the wall or roof.
  • Decorative overlays. Flanges covering the passage of the passage of the chimney through the building structure.

For the manufacture of parts for coaxial chimneys used galvanized or stainless steel. It is resistant to high temperatures, durable and light. Some models are made of aluminum alloys or heat-resistant plastic. For joints, seals are used, made of heat-resistant polymers that can withstand temperatures of about 230-250 °.

Coaxial chimney
Coaxial chimneys are standardized modules from which a structure of the desired size and configuration is easily assembled.

Types of coaxial type chimneys

There are several types of construction "pipe in pipe". Consider in detail each of them.

External and internal systems

All coaxial flues, depending on their location, are divided into external and internal. The first are located on the outside of the building and are fixed directly on the facade. Given that such structures somewhat spoil the appearance of the building, they are trying to place them on the inner sides of the building. A distinctive feature of the exterior chimney - easy maintenance and installation.

Internal structures are mounted in specially laid mines that run inside the building and are separated from the living quarters. In some cases, traditional chimneys can be used as such mines. It is important that their device and dimensions fully comply with modern fire safety requirements. Internal systems are quite difficult to maintain and install.

Not warmed and warmed devices

In cold weather, especially in severe frosts, the channel that feeds air into the system may freeze through. In this case, the amount of oxygen entering the combustion chamber decreases sharply, which leads to deterioration of the heater. In some cases, and to his stop. Therefore, where low temperatures last for a rather long period of time, as well as where there are frequent severe frosts in winter, it is recommended to install heat-insulated systems.

Insulated coaxial chimney
Insulated coaxial chimneys are distinguished by the presence of another pipe. A layer of non-combustible heat insulator is laid between it and the external part, which prevents the structure from freezing.

The coaxial flue of the warmed type differs from the standard one by the presence of one more pipe. The system looks like three nested parts. The free space between the two extreme elements is insulated. To this end, it is filled with any suitable insulation. It reliably protects the air channel from frosting and frost penetration.

Horizontal or vertical output

Initially, coaxial chimneys were designed as horizontally oriented systems, but in practice such an arrangement is not always possible. Most chimneys of this type are mixed constructions. They can contain both vertically oriented and horizontal sections. This is due to the location of the heater in the building. In some cases, it is possible to use vertical chimneys, but only for boilers without forced draft.

Collective and individual designs

For maintenance of one heating device, individual coaxial chimneys are used. These are simple, branchless systems that may have a different configuration. To work with multiple boilers mounted collective chimney. This is a mine system with several branches. In addition, each of the branches goes to one of the heat generators. Such a design can only be vertical.

Collective coaxial chimney
The collective coaxial type chimney is characterized by the presence of several heat generators connected to one mine. It can be both external and internal

Why choose coaxial systems

The design features of a coaxial type chimney enable it to operate on a different principle from the traditional chimney. To ensure combustion, oxygen must be supplied to the boiler furnace, and the combustion products should be removed. Boilers equipped with separate chimneys draw air from the room in which they are installed. It is dangerous enough for a person and requires constant airing of the room.

Exhaust gases are discharged to the outside through natural draft. Appliances with coaxial chimneys work differently. Such chimneys are a combined air supply and smoke exhaust system. The thrust required for the operation of the device is created in a natural way or with the help of a fan, which makes it possible to use structures of small length.

Advantages of installing a coaxial chimney
Weighty plus chimney coaxial design - ease of installation and the ability to bring the combustion products by the nearest way, for example, through the wall

Thus, the complete isolation of the exhaust of combustion products and the supply of oxygen makes it possible to completely eliminate their impact on the composition of the air in the room where the boiler is installed. Oxygen "burning out" does not occur, as a result of which ventilation of the room is not required. The amount of air in the combustion chamber is optimal, which increases the percentage of fuel combustion and, as a result, the boiler is more efficient and environmentally friendly.

Hot smoke from the heater is discharged through the inner tube. It passes inside another, through which the cold air moves. Thus, there is no thermal effect on the walls and floors, inside which the chimney is laid. This significantly increases its fire safety, which is very important for buildings made of wood and other fairly flammable materials.

Coaxial chimney
The figure schematically shows the main difference between coaxial chimneys and traditional ones. The first takes the air outside, the second - indoors, which is dangerous for those who are in it

The coaxial system increases the efficiency of the heater. This is due to the fact that the air supplied to the furnace, passing through the internal cavity of the structure, heats up from the pipe that removes the hot smoke. Another significant advantage of chimneys of this type is compactness and relatively small size, especially compared to traditional separate chimneys.

It would be a mistake to think that the system has no flaws. They are. First of all, it is quite a high cost of such a design. On average, it is 40% more expensive than traditional. Another is due to the coaxial-type chimney device. Pipes with hot smoke and cold air in contact, which inevitably leads to the formation of condensate, especially in cold weather. Thus, the system needs to arrange a special drain for condensate and additional insulation, which further increases its cost.

How to choose device dimensions

The technical documentation that is attached to the chimney must indicate its diameter. The designation represents two digits written through a fraction. The first one shows the diameter of the inner tube, the second one - the outer one. To choose the desired size is quite simple. It must be indicated on the boiler passport, which will be connected to such a chimney.

Coaxial chimney
The dimensions of the coaxial type chimney are selected in strict accordance with the type of the boiler and the size of its outlet nozzle of the boiler. All necessary information should be in the technical documentation of the heater

In this case, the determining factor will be not only the diameter of the system, but also its length. The latter is defined as the sum of the lengths of all sections of the chimney. It has limitations, fixed in the installation instructions, and is measured in equivalent meters. In addition, all these nuances are indicated in the selection table, which should be attached to the technical documentation of heating equipment.

Installation of chimney in the light of regulations

A coaxial type smoke evacuation system can be installed in a private house or apartment building. The latter is also quite common, especially in connection with the widespread installation of individual heating systems in apartments. Until 2012, the design and installation of coaxial-type chimneys in apartment buildings and private houses were regulated by one SNiP and did not differ.

In 2012, a set of rules SP 60.13330.2012 was adopted, which is an updated version of SNiP 41-01-2003. The document divided the conditions for installing a coaxial chimney in an individual and apartment building. In the latter case, it is prohibited to install individual chimneys in apartments, as was allowed earlier, and the installation of a collective chimney is prescribed.

Therefore, you need to be very careful and know that if the designers offer to arrange an individual allotment exhaust gas from a heat generator located in one of the apartments of an apartment building, this is contrary to current regulations. The distance from the ridge of the building’s roof to the cross-section of the smoke exhaust channel should be not less than 1.5 m. A similar value for a private house is from 0.5 m.

Coaxial chimney
The outlets of the coaxial chimneys must be located at a sufficient distance from the windows, otherwise the smoke will enter the room

Special acts regarding individual buildings were not adopted, therefore it is believed that their The arrangement should not contradict the requirements applied when installing chimneys in multi-unit homes. Based on the new edition of the SNiPa, coaxial systems of any type can be installed in private homes. In multi-unit - only vertical.

An important nuance. If in a building until 2012 chimneys were installed that contradicted the current edition, they can be left unchanged if they do not cause inconvenience to neighbors.

Some installation features

For each boiler, the direction of the channel that discharges the combustion products is determined individually. Horizontal systems can only be used for devices with forced ventilation.

Coaxial chimney
Errors in calculations and installation can lead to freezing of the system and freezing of condensate at the outlet. In such conditions, the boiler will not be able to work

But even in this case, the maximum length of such a section should not be more than 3 m. It happens that the manufacturer establishes other standards for their boilers, so you should be familiar with the technical documentation devices.

Vertical-type constructions for private houses are used only if there are reasons that prevent the exit of the smoke outlet through the wall. It can be close to the outlet window, a narrow street on which the building stands, and the like. In some cases, if it is very necessary, inclined installation of a coaxial chimney is allowed.

The optimal distance to install coaxial chimney
Options for the passage of a coaxial chimney through building structures and the distance between the chimney and the elements of the house are based on many years of operating practice

The system is connected to the heater with a tee, elbow or pipe. In this case, the diameters of the discharge channel and the outlet of the boiler must be the same. In the process of installation, all subsequent parts are fixed in the preceding ones so that no obstacles are formed that can disrupt the movement of combustion products. The number and type of elements for assembly are directly dependent on the location of the outlet.

If it is located on the side, the arrangement of the horizontal system is supposed, if it is on the top - vertical. The latter option is more simple to install. In the process of arranging the coaxial chimney, transition units with rigid fastening of the junction of the two elements with the help of clamps are necessarily used. Some "craftsmen" prefer to use homemade options.

Coaxial chimney
The figure shows the layout of the passage of a horizontal coaxial chimney through the wall

These can be self-made adapters, tape windings or sealant seals. Such things are unacceptable to use because they are extremely unreliable. A system assembled with such elements is considered unsafe in operation. In addition, the following rules are observed during installation:

  • The horizontal chimney exit should be tilted down 3 °. At the horizontal section of the chimney, the horizontal section is tilted in the opposite direction, i.e. it decreases towards the boiler. This is necessary for unobstructed draining of condensate.
  • Throughout the chimney channel should not be more than two folds.
  • Inspection hatches, adapters and a condensate discharge device should be readily available for periodic inspection.
  • Chimney cannot be moved below ground level. At the same time, the distance from the coaxial chimney outlet to the neighboring building should be more than 8 m. If the pipe a deflector is installed, this distance is reduced to 2 m for a blank wall and 5 m for a wall with window openings.
  • If the horizontal chimney is installed in a place where winds prevail, the direction of which is opposite to the direction of smoke diversion, it is necessary to install a tin barrier at the pipe outlet. The distance between it and the outlet should be at least 0.4 m.
  • On coaxial chimneys, towering above the ground level less than 1.8 m, it is necessary to install a deflector grille. It will work as protection from hot smoke.

All structural elements should fit snugly together. Each subsequent part must go inside the previous one at a distance equal to not less than half the diameter of the channel section. To encircle the structure around any obstacles, specially designed knees are used. The angle of inclination may be different. If the system is displayed through the roof, all fire safety requirements must be met.

Coaxial chimney
Arrangement of the passage of a coaxial chimney through the roof or through the wall must be carried out with strict observance of all fire safety requirements

For this purpose, special insulating pipes and non-combustible insulation materials are used. There must be an air gap between the pipe and the overlap. In order to avoid contact between the chimney channel and fragments of the roofing cake, a protective cover is used. The exit of the structure through the roof is carefully sealed. Sections of the joints are covered with a special apron.

Coaxial chimney mounting technology

The installation process of external and internal coaxial chimney has differences. Consider both options.

Installation of the internal system

First of all, we check the conformity of the diameters of the boiler outlet and the chimney. Then proceed to the preparation of the hole in the wall through which the smoke outlet will go out into the street. Its diameter must exactly match the size of the coaxial tube. After making the hole, you can proceed to the installation of the structure. It starts from the outlet of the boiler, to which the corresponding element of the chimney is attached.

The resulting connection is fixed with a collar and secured on both sides with bolts. Further consistently assemble the entire structure. Each element is inserted into place and secured with special clamps to give the system additional reliability. Overlays are installed overlays, so the attractive appearance of the structure is preserved.

The chimney is brought out through the wall to the street. If necessary, a deflector or additional wind protection is installed on the outlet pipe. The passage in the wall is sealed. At the same time, fire safety requirements are complied with. A special protective cover is put on the pipe. The joints of the passage are sealed and covered with an apron.

Coaxial chimney
External chimney coaxial type vertical orientation. Such systems are quite simple to install.

Mounting external structure

Before its beginning, the place of exit of the coaxial chimney is determined and its location on the wall of the building is planned. Then a hole is made in the wall with a diameter corresponding to the cross section of the smoke outlet. Further, all the internal work. Begin by connecting the pipe to the heater. For this, a single-circuit knee and a double-circuit tee are used.

The latter is needed to secure the structure in a vertical position. The resulting structure is fixed on the wall surface with special brackets. Further, all work is carried out similarly to the method described above. The chimney exit section is sealed and the pipe is being assembled to the desired height. The design is fixed to the wall with clamps. To connect the dual-circuit pipes used transition nodes.

Useful video on the topic

Device and installation of coaxial chimney

Installation of coaxial type chimney in a wooden house

How to install a coaxial chimney yourself

The coaxial flue is an effective and practical device that significantly increases the efficiency of the heater. In addition, it is absolutely safe to operate, compact and quite simple to install. The only significant disadvantage of it is the relatively high cost of arranging such a system, which, however, pays off with its long-term effective work.

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