Coaxial chimney installation regulations: requirements and rules

Choosing the optimal chimney for a gas boiler is not an easy, but quite realistic task. After all, I want this to be an extremely simple to install and operate design, and even with high efficiency. All requirements are met by a coaxial type, the installation of which may become a kind of "catch." Do you agree?

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

In our proposed article describes in detail the installation of a coaxial chimney. There are useful schemes for its competent assembly and installation. Information is confirmed and supplemented by photo-clips and video tutorials.

The content of the article:

  • Principle of operation and device
  • Features of installation of coaxial chimneys
    • Basic installation requirements
    • Misuse problem
    • Basics of choosing a horizontal or vertical type
    • Good ventilation device
  • Conclusions and useful video on the topic

Principle of operation and device

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

To make a coaxial chimney, you must take two pipes of different diameters and put the narrow pipe inside wide. You also need to connect the inner side of the wide pipe and the outer side of the 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, of course, easier and safer 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 pay off in full.

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Coaxial chimney on a log gable

The use of a coaxial chimney allows you to remove the products of combustion through the facade of the house, there is no need to install 5 m of vertical chimney

Affordable and implementation options

The assembly of a coaxial type chimney can be done with your own hands, at a cost it is the cheapest way to make a chimney

Installation paired with any type of equipment

Coaxial pipes, round in cross-section and smooth inside, best of all remove smoke formations of boilers and furnaces on solid and liquid fuel, are considered ideal for working with gas equipment

Vertical options for coaxial designs

In addition to horizontal schemes for installing coaxial pipes, vertical ones are actively used, because during operation oxygen is not burned in the room.

Errors in the installation of a horizontal pipe

Installation of the chimney should be carried out in accordance with the manufacturer's instructions. For example, a slope of 1 cm by 1 m should be observed towards the head of the pipe so that condensate does not flow backwards.

Insulated pipe modifications

Coaxial systems are produced in the insulated version and in versions without insulation. When using insulated elements, the chimney can be brought above the roof and lay a large part of the pipe parallel to the facade

Length of horizontal sections

The length of the horizontal part of the system is limited by the manufacturer’s instructions. Usually it can not exceed 3 - 4 m

Conclusion coaxial pipe on the gable

Due to the smoke discharged into the atmosphere, the coaxial chimney cannot be installed closer than 1 m under the windows. Exception - gable ventilation windows

Coaxial chimney on a log gable

Coaxial chimney on a log gable

Affordable and implementation options

Affordable and implementation options

Installation paired with any type of equipment

Installation paired with any type of equipment

Vertical options for coaxial designs

Vertical options for coaxial designs

Errors in the installation of a horizontal pipe

Errors in the installation of a horizontal pipe

Insulated pipe modifications

Insulated pipe modifications

Length of horizontal sections

Length of horizontal sections

Conclusion coaxial pipe on the gable

Conclusion coaxial pipe on the gable

Double pipe is necessary for the simultaneous performance of two functions. Combustion products are discharged from the inner narrow pipe from the boiler furnace. And through the lumen between the inner and outer pipe air enters the combustion chamber, i.e. oxygen required for burning fuel.

This solution has a number of advantages. An alternative to a coaxial chimney is the traditional chimney in combination with the forced injection of air into the combustion chamber.

In this case, the air is usually taken from the room in which the boiler is installed. Coaxial chimney allows you to take air from the street and feed it directly into the furnace.

Coaxial chimney operation scheme

The diagram shows the general principle of operation of the coaxial chimney, as well as its device compared to the traditional chimney (+)

What happens in such a chimney while the boiler is running? Hot combustion products move through the inner tube to the outside, and in the opposite direction there is a parallel stream of fresh cold air. As a result, a completely natural heat exchange takes place: the hot gases give off heat to the neighboring cold stream.

The air enters the combustion chamber already in a heated state, which increases the overall efficiency of the boiler, because you do not need to spend precious kilojoules to heat the air masses. The temperature of the outer surface of the coaxial chimney is noticeably lower than when using a standard chimney. This circumstance makes the design more secure.

Another advantage of coaxial chimney is simpler. boiler installationbecause you don't have to install the system forced ventilation. In addition, these structures have different requirements than traditional chimneys. As a result, the system for removal of combustion products takes up less space.

Coaxial and traditional chimney

On the outside of the building, the coaxial chimney pipe looks much more concise and takes up less space than with the external installation of a traditional chimney.

Coaxial chimneys are universal, they can be installed with gas boilers, and with devices operating on liquid or solid fuel. Chimneys with different diameters are on sale, which allows choosing suitable pipes for a specific boiler.

Installation of a traditional chimney in an already constructed building is a rather complicated task. If a chimney installation was not foreseen in the design, it is necessary to pass overlappings and roofing or take the chimney out.

A bulky construction can create problems both inside and outside the building. But coaxial designs are simpler and more compact. The conclusion of such a chimney on the outer wall looks concisely, it will not spoil the appearance of the house.

Features of installation of coaxial chimneys

Chimneys of this type can be installed horizontally or vertically. The preferred option is the first option, which is considered simpler and takes up less space. At the same time a number of requirements should be observed:

  • the distance from the pipe to the ground level on the outside of the house must be at least 2 m;
  • the pipe should be no less than half a meter horizontally from windows, doors, air vents, etc .;
  • the same distance to these objects should be kept vertically;
  • if there is a window above the ventilation duct, the distance to its lower edge should be at least one meter;
  • the free space in front of the coaxial pipe must be at least one and a half meters, i.e. there should be no walls, fences, pillars or other such obstacles;
  • if there is no special device for collecting condensate, the coaxial chimney pipe should be placed on a slope to the ground;
  • the size of such a slope can vary within 3-12 degrees;
  • It is not allowed to remove the chimney channel not into the street, but into another room or structure: an entrance, a basement, a tunnel, an arch, etc .;
  • a distance of not less than 20 cm should be kept between the elements of the chimney and gas pipes, if they pass nearby.

We should also consider the situation when the exit pipe of the coaxial chimney is located under the balcony or some canopy. This is a perfectly acceptable situation, but it is necessary to consider the next point.

It is necessary to mentally draw a circle in the plane perpendicular to the wall. The center of the circle will be the junction of the shed and the wall, and the radius will be the length of the shed or balcony.

The chimney pipe should protrude beyond this conditional boundary. It turns out that the closer to the canopy there is a hole for the chimney, the longer the outer part of the pipe should be.

Coaxial chimney installation requirements

This diagram clearly demonstrates the basic requirements for the placement of a coaxial chimney with respect to various objects located near it (+)

It is believed that the length of a coaxial chimney using a horizontal installation scheme can not be more than three meters. This is a general rule from which exceptions exist. For example, some Ferroli chimney models may be four or five meters long.

The set of materials for installing a coaxial chimney depends on the type of its location, but in general the list of elements may look like this:

  • chimney proper;
  • adapter for connecting the boiler to the chimney structure;
  • knee, tee, etc .;
  • crimping clamps for reliable connection of elements.

Usually, the delivery kit for a coaxial chimney includes all the elements necessary for its installation. To hold the pipe through the wall, ceiling or roof, you must use fire-resistant gaskets. They will prevent overheating and ignition of surrounding materials.

Elements of coaxial chimney

This diagram shows the individual elements of a coaxial chimney. If the pipe needs to be expanded, additional industrial parts should be ordered (+)

Here is one of the options: they make a hole in the wall and insert a sleeve from an asbestos-cement pipe into it. Then the space between the surface of the coaxial pipe and the sleeve is filled with asbestos cord. All elements of the coaxial chimney must be manufactured in industrial conditions and meet the established standards.

It is not recommended to use home-made designs, even for an adapter. Some amateur craftsmen are trying to increase the length of the pipes using sealing tape and high temperature sealant. But this option does not hold water in terms of safety.

Basic installation requirements

The type of installation - horizontal or vertical - depends on the characteristics of the room in which the boiler will be placed. There should not be any foreign objects in the space between the boiler and the wall, into which the coaxial chimney will be led, this is an important safety requirement.

At the same time, the exit point of the chimney pipe from the wall and the pipe of the boiler, to which it is connected, should be separated not less than 1.5 m vertically. The pipe should also have a small slope - about 3 degrees to ensure the outflow of moisture condensed on the surface of the communications.

Installation of coaxial chimney

The space between the boiler and the wall into which the coaxial chimney is led must not be encumbered with any foreign objects.

The next important parameter is the diameter of the pipe and the nozzle of the boiler. In size, they must match. In no case is it allowed to install a pipe whose diameter is narrower than the dimensions of the outlet of the heating device.

Before installation, carefully review the technical data sheet and boiler deviceto ensure that the dimensions of the nozzle and chimney meet the established standards. The boiler pipe can be located on top or side. It is believed that the top location of the nozzle simplifies installation.

Coaxial chimney adapter

The dimensions of the boiler pipe for the chimney, the adapter and the coaxial pipe must match each other. The use of pipes of smaller diameter is not allowed.

To connect the chimney pipe usually use an adapter in the form of a tee, elbow or a piece of ordinary pipe. At the same time inside the adapter should not be any obstacles to the advancement of gas and air masses.

If the length of the coaxial pipe has to be increased, care should be taken to ensure that the connection is tight. For this use crimp clamps. Similarly connect adapters, knees and other elements of the chimney.

Installation of a coaxial chimney

The individual elements of the coaxial chimney are inserted into each other in such a way as not to create obstacles to the movement of air and combustion products. Connection points are rigidly fixed with hose clips (+)

It is not recommended to perform a design that includes more than two knees. The total length of a coaxial chimney consisting of several multidirectional sections should be no more than three meters.

During the installation of a coaxial chimney, its lower elements are inserted into the upper and rigidly fixed clamps. This method of connection allows for good traction. The individual elements must enter each other at a depth of at least half the diameter of the structure in accordance with the requirements for coaxial chimneys.

For reliability, the exit point of the pipe from the outer wall is blown with assembly foam. Special decorative grilles are installed on top to make the installation site look attractive. The grid can be glued with a suitable adhesive composition, for example, liquid nails.

The part of the coaxial chimney that is laid indoors can be masked, for example, using a drywall box:

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Step 1: Masking Device

In order to hide the lining of the inner part of the coaxial pipe, constructed a box of drywall. CD guides are installed for its installation.

Step 2: Foaming the hole in the wall passage

Before sewing the frame, the gaps in the hole through which the coaxial pipe goes outside should be replaced with foam. The solution is not used, because the pipe vibrates slightly during operation

Step 3: Sew the lower tier of the frame

First, a part of the frame is sewn adjacent to the wall, which masks the base of the structure

Step 4: Installing the duct over the coaxial tube

Install the outer part of the drywall duct directly above the pipe. Seams and attachment points are treated with primer before finishing the wall.

Step 1: Masking Device

Step 1: Masking Device

Step 2: Foaming the hole in the wall passage

Step 2: Foaming the hole in the wall passage

Step 3: Sew the lower tier of the frame

Step 3: Sew the lower tier of the frame

Step 4: Installing the duct over the coaxial tube

Step 4: Installing the duct over the coaxial tube

Misuse problem

Regarding the slope of the coaxial chimney pipe, the question may arise: where exactly should it be directed? Some experts argue that the condensate should flow towards the boiler. According to other masters, the slope must be done in the opposite direction, so that the moisture flows down the pipe to the ground. In both cases, reasonable arguments are given.

It looks quite logical option in which droplets of condensate are moved as far as possible from the boiler. The firebox is protected from waste moisture, which remains outside the house and naturally dissolves in the environment. Everything looks that way until the ambient temperature drops below zero.

Coaxial chimney icing

Coaxial chimney fouling is a natural but dangerous phenomenon. Ice deposits prevent the removal of combustion products and the entry of fresh air into the furnace

When frosts occur on a coaxial pipe installed with a slope to the ground, droplets of condensate freeze, forming an ice crust. Icing can be observed both on the outside of the chimney and in the space between the two pipes of coaxial construction.

This occurs because the temperature of the external contour of the chimney of this type is low, it is not enough to quickly melt the frost. As a result, ice deposits create obstacles for the normal flow of air into the furnace, as well as for the effective removal of combustion products.

And this reduces the efficiency of the device. Long-term operation of the boiler with an icy coaxial chimney can even lead to significant equipment breakdowns. It turns out that in warm regions, where even in winter there is almost no frost, a coaxial chimney can be installed with a slope to the ground.

In all other cases, it is recommended to tilt the pipe towards the boiler, which usually corresponds to the recommendations of the manufacturers of these structures. What to do with the condensate, which with such an installation will flow to the heater?

It's simple, you need to install and use a special tank for collecting condensate. Such a condensate trap is a small device that copes with its tasks quite satisfactorily. Partially, the problem of freezing the chimney can be solved with the help of its insulation, but this measure does not provide one hundred percent guarantee.

Condensate collector for coaxial chimney

This diagram shows the device of a special element - a collection for condensate. It picks up droplets of moisture flowing through the coaxial pipe to the boiler, and protects equipment from corrosion.

Some craftsmen believe that to prevent condensate from freezing in a coaxial chimney with a slope to the ground You can, if you shorten the inner tube, but experts do not recommend changing their own construction

On the issue of icing coaxial chimney there is also another interesting opinion: the larger the diameter of the pipe, the lower the probability of condensate freezing. While the craftsmen broke spears, discussing the optimal slope of the coaxial chimney, manufacturers took care of creating a special kit.

Coaxial Chimney Anti-icing Nozzle

To prevent the icing of the coaxial chimney, it is recommended to use a special model with an anti-icing tip. Air is drawn into such a pipe through the holes on its underside.

This design is resistant to icing and is designed to operate in the harsh Russian winter. This device is equipped with an extension nozzle for a gas exhaust (ie inner) pipe. Inside the nozzle is installed a narrow protective helix. In this case, the air intake holes on the edge of the outer pipe are located below.

Basics of choosing a horizontal or vertical type

It is not always possible to fulfill all the requirements for horizontal installation of a coaxial chimney. Difficulties may be encountered if the room where the boiler is installed is very small. Problem may be the outer side of the building. For example, when there are windows close to each other.

Vertical Coaxial Chimney

If necessary, the coaxial chimney can be removed vertically through a sloping or flat roof using appropriate weather nozzles. The length of such a chimney depends on the power of the boiler connected to it (+)

It also happens that the distance to neighboring buildings is too small to ensure normal coaxial chimney draft. If it is not possible to comply with all the conditions for horizontal installation of the structure, preference should be given to vertical installation, i.e. pull the pipe through the roof.

With vertical mounting of the coaxial chimney, as with installing a traditional pipebrackets are used. They allow you to hold the structure in the correct position and at a distance from the walls.

When removing the coaxial chimney through the roofing pie, special attention should be paid to fire safety issues. Here insulating pipes should be used, and the use of fire-resistant insulation is recommended.

They also use protective covers to isolate the chimney from contact with other objects and materials. A small air gap should be left between the coaxial pipe and the overlap section, but the roof at the exit point of the pipe is sealed very carefully. Place the junction of the pipe and roof covered with a tight protective casing.

Good ventilation device

It may seem that a heating device with a closed combustion chamber and the presence of a coaxial chimney relieve home owners of the need to provide the boiler room with normal ventilation. Indeed, the air enters the furnace from the outside, and the products of combustion are removed through a reliable hermetic channel.

However, the need to ventilate the room in which the boiler is installed is still necessary. For a start, a normal air exchange will allow you to maintain an optimal level of humidity in the room, which prevents the development of corrosion processes and protects the equipment from damage.

And it should be noted that any system may eventually fail. If the boiler room is adjusted good ventilation, in the event of a breakdown, a small amount of carbon monoxide will be removed from the room naturally. As a result, the risk of accidental carbon monoxide poisoning becomes significantly lower.

Conclusions and useful video on the topic

Video # 1. The device of a coaxial chimney, its principle of operation and installation features are presented in the following video:

Video # 2. It shows in detail the equipment of the coaxial chimney of industrial production:

Video # 3. An overview of the anti-icing coaxial kit:

Coaxial chimney is a convenient and easy to install device that can significantly improve life in the house. But in order for such a chimney to function efficiently, it is important to comply with the norms and requirements during its installation.

There were questions in the course of familiarization with the material, found shortcomings, or is there a desire to tell about your own experience in assembling and using a coaxial chimney? Please post comments in the box below the article. Leave posts with your opinion and photos on the topic.

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