Do-it-yourself coaxial chimney: types, design requirements, installation and operation. Coaxial pipe for a boiler: advantages, disadvantages and installation instructions Is it possible to make a coaxial chimney separate

The issue of autonomous heating will be resolved individually. Very popular gas boilers with a coaxial chimney due to excellent efficiency, availability of fuel and reasonable cost. The main advantage of such a system is the possibility of installation after the house has been built. This article will discuss how to install a coaxial boiler.

The installation of equipment can be entrusted to specialized companies that will carry out turnkey work. Thus, saving owners from coordinating documentation with competent organizations and installation nuances.

However, if you want to carry out installation work on your own, then knowing the operating principle of gas equipment and observing all the norms and regulations (SNiP), you can cope with this process without any special difficulties.

Single-circuit coaxial boiler

Operating principle of a coaxial boiler

The coolant, usually water, enters the heat exchanger, where it is heated to the desired temperature due to gas combustion. The device has 2 igniters (main and additional, used to maintain the “sleep” mode). Ignition can be manual or automatic.
The equipment is divided into single-circuit and double-circuit. In the first case, the models are intended only for connecting a heating system. Gas units with two circuits provide not only heat in the house, but also heat water for domestic and economic needs.
The combustion chamber is isolated from external influences. The influx of air masses from the street and the exit of carbon dioxide (combustion products) is carried out through a coaxial channel. Its pipe-in-pipe design does not allow mixing of two different flows.

Basically, all units are equipped with control and safety systems. Automation consists of thermostats, indicators, reset and safety valves, sensors, fans, etc.

Types of coaxial heating boilers

Boilers differ not only in technical specifications, but also by installation methods. They are floor and wall mounted. The latter type is much lighter and does not take up much usable space.
With compact dimensions, the power of the equipment is correspondingly reduced. Its installation is carried out for heating greenhouses, office and residential premises with an area of up to 150-250 sq.m.
The floor-standing coaxial boiler, due to its large combustion chamber, has a high efficiency. Such models are suitable for heating and providing hot water to industrial buildings and large residential buildings.

For the manufacture of cases they use various metals and their alloys. The most popular devices are made of cast iron and steel. Such products are characterized by good performance at an affordable cost.
Copper and silumin boilers are distinguished by their high reliability, heat transfer and long service life. However, their cost stops many consumers from purchasing them.

Nuances of choice

To select equipment, it is better to consult with specialists; it would not be a bad idea to ask the opinions of neighbors or relatives who operate such devices.

Their disinterest will help to give a more objective assessment of the boiler’s operation, to note the absence of one or another function, or, on the contrary, to emphasize a wide range, half of which is not necessary to use.

As a rule, devices have a combined operating mode - gas and electricity. When purchasing, give preference to non-volatile models, otherwise you will have a hard time if there is a power outage. The equipment can be equipped with a source uninterruptible power supply. The power of modern UPS is 200-350 kW/h.

IN general outline the plan will consist of the following points:

obtain permission for installation from the gas service;
based on the project, prepare a place for installation of equipment and chimney wiring;
choosing a boiler by power, size, brand, appearance and other parameters.

The consumption of natural or liquefied gas determines the performance of the unit. As a rule, for every 10 sq.m. area consumes 1 kW/h. It follows from this that for a building of 100 sq.m. You need a device of at least 10 kW. Thus, a device with a minimum power of 10 kW/h consumes 1.12 cubic meters. natural gas or 0.86 kg/h liquefied propane-butane.

Country of origin of coaxial gas boilers

As for the manufacturer, the leading places are occupied by factories Sweden and Germany. Their products are characterized by reliability, quality and functionality. High positions are supported by an equally high cost.

Italian boilers have stable quality without complaints. However, positive recommendations are given only for devices assembled in this country. Chinese assembly reduces all advantages to zero.

Equipment from Czech Republic quite unpretentious. However, their weak point is electronics, which is especially important to keep in mind, because instability of the voltage supply in electrical networks is typical for our country. The solution may be to install a stabilizer.
TO budget options include boilers of domestic, Korean and Chinese production. This category can be called a “happy accident”, that is, you can buy a cheap boiler that will surprisingly last for many years or, as often happens, a breakdown will occur in the midst of the first heating season.

Requirements for installing a coaxial boiler

When choosing a location for placing gas coaxial equipment, it is necessary that it meets the following requirements:

presence of a ventilation system and gas analyzer;

When installing a suspended heat generator, the wall is insulated with non-combustible material;
installation of floor-standing models is carried out on concrete base or metal sheet;
It is prohibited to place other gas appliances and electrical equipment closer than 30 cm to the main boiler.

If you comply with the above norms and rules, you can count not only on the effective operation of the system, but also on the safety of all family members.

Attention: when installing a boiler with an open firebox, the requirements are more stringent!

Coaxial chimney

Boilers with closed camera combustion systems are installed much more often compared to other types of heating equipment. Their main advantage is the possibility of installation in rooms not equipped with special stationary hoods. For the heat generator to work, a coaxial channel is required, which is discharged through a window or a technological hole in the wall.
Equipment of this design can be installed in attics, kitchens and basements. Here, only one condition is necessary - the presence of a window or the ability to drill through the wall for the chimney pipe to exit.
The design consists of two pipes of different sections inserted into each other. Combustion products exit through the inner pipe. The distance obtained by the difference in diameters is used to draw in fresh air masses.

The features and advantages of a coaxial chimney include:

the flow of air with the simultaneous removal of combustion products provides protection against the entry of carbon monoxide into the room;
the special design does not allow heating the outer casing of the pipes, which means it does not transfer heat to the walls, which is not safe for wooden buildings;
This system increases the efficiency of the entire heating system of the house as a whole, by partially heating street air.

Channels are purchased separately from the boiler, large selection provides the opportunity to select products not only of the required diameter, but also of the preferred material (polymers, ceramics, galvanized steel, etc.). Sometimes pipes are included with the gas device.

Installation of coaxial boilers

The equipment is installed no closer than 60 cm from the window opening; such standards are determined so that the escaping carbon monoxide does not return back. If such conditions do not exist, use the maximum possible distance.

Floor boiler. This unit requires a level base. A technological gap is left between the rear wall of the housing and the wall of the building for servicing the device. Having placed the unit in the intended location, assemble the coaxial system. Then mark its exit point on the wall with minimum distance 1.5 m from the floor.
Wall-mounted boiler. Installation of this type of device is carried out on a load-bearing or reinforced wall. Estimate at what height it will be convenient to service it, optimal parameter- 1-1.6 m. At this level, mark points for the bar (it is included in the kit). Check the levelness with a building level.

Place the boiler on the mounting strip. Next, you need to assemble the chimney duct and determine where to drill a hole for the pipe. Here it should be taken into account that with a horizontal outlet of the channel, the slope must be at least 3 degrees. This will greatly facilitate the drainage of condensate.

Chimney hole

After moving or removing the equipment, use a hammer drill with a special attachment to drill a hole of the required diameter. The pipe must pass freely into it. The crown is selected depending on the material from which the walls are built (wood, brick, concrete blocks).
There is no need to worry about the interior and exterior. Special decorative overlays are available for sale.

Assembly of coaxial pipes

Each specific case determines the direction of the channel. This can be inclined, vertical or horizontal.

Advice: horizontal movement of the system is only possible with forced ventilation!

The vertical direction is more often used when it is not possible to make a channel exit through the wall. In this case, it is necessary to calculate the path of the channel through the roof so that the pipe does not rest against joists or other structural parts of the roof.

For the chimney, use factory-made fittings and components. With their help, assembly and installation will be better and more reliable. Try to avoid numerous bends and turns.
Maximum simple form channel will work more efficiently. When extending the channel, but not more than 3 m, special clamps are used.

Advice: it is prohibited to use sealant or any other available materials.

Assembly of the entire system

The final assembly of all system elements begins with the installation of gas equipment in place. The boiler is connected to the gas supply. A special rubber hose is used for this. The tightness of the connections is checked by wetting them with a soap solution.
An adapter is used to connect the pipe to the equipment. Next comes a vertical extension, a connecting clamp, and then an elbow for horizontal rotation of the channel. You can immediately use the elbow after the adapter.
A pipe of the required length is connected to the elbow, followed by a discharge channel. The distance must be calculated so that this element protrudes onto the street by at least 30 cm.
With a horizontal outlet, a condenser collector is required. It is mounted at the bottom of the structure.
Now all that remains is to connect the boiler flare to the water supply system.

Before work, contact the authorized bodies to obtain permission to install and operate heating equipment. The ease of installation of the boiler itself and the coaxial chimney should not be misleading. Only by adhering to the attached instructions and observing the requirements of SNiP can we talk about the quality of heating of the premises and the safety of all residents.

IN modern world The coaxial chimney for a gas boiler has become very popular. When installed correctly, such a pipe performs two important functions at once: it removes combustion products and guarantees the necessary air flow for operating the heating system. There are several types of chimneys, which differ in design, material and technical properties.

These designs differ in some characteristics

Main characteristics

In order for a heating system in which an open flame burns to function properly, two rules must be observed: a regular supply of air in sufficient quantities is necessary, and the safe removal of combustion products and exhaust gases into the environment must be established.

If the private sector can use stove chimney, then in a city apartment it will be very difficult to implement this option. However, in both cases this method will have many significant disadvantages:

For the flame to burn, a significant influx of air is needed, which will be borrowed from the living space. This promotes drafts and also increases the flow of cool air from the street.
Stove chimneys installed in private houses are most often made in the form of brick blocks with vertical or horizontal smoke channels. Manufacturers of gas boilers strictly prohibit connecting them to such chimneys.
In order to make a separate chimney with exhaust in the apartment, you will need a lot of money. This is a difficult task to achieve, since, in addition to the large financial costs of installation and production, permission will be required from the executive authorities that are responsible for the visual component of the city.

In this video you will learn how to modify a coaxial chimney:

In view of these factors, the installation of coaxial chimneys for boilers is considered the most rational. In addition, this is an economical option that does not require huge funds for purchase and installation.

Appearance and principle of operation

The design of such a chimney consists of one long metal pipe, located inside another, shorter, but with largest diameter. In addition, the set contains various connecting accessories - elbows, clamps, linings - as well as a receiver for collecting condensate.

The types of such equipment may have slight differences, but the device diagram and operating principle are almost identical for all systems:

A thin inner tube is necessary to remove combustion products. It is made from high quality and reliable stainless steel. The inner end is connected to the hole at the boiler outlet, and the outer end is led outside the living room to the street.
The outer pipe is responsible for the flow of air from the environment into the combustion zone. Its inner end is connected to the hole at the entrance, and the outer end is removed from the living area.
The spent waste is discharged into the atmosphere through the inner pipe due to draft, and in its place clean air enters the combustion area through the outer pipe.
The outer pipe does not come into direct contact with hot gases, but it is located in an area of strong temperature difference. This part can be made from cheaper steel.

Don't forget that the kit includes various connecting devices.

Types of chimneys

How combustion products will be removed is influenced by the type of gas boiler, as well as the layout of the room that will be heated. This process can occur in two ways: through the outer area of the building to the side or through the ceiling and roof of a private house. Therefore, coaxial chimneys for gas boilers are divided into two types: vertical and horizontal.

A vertical coaxial chimney for a gas boiler is used only in the private sector. It is designed to remove waste elements through the ceiling. This method is more environmentally friendly and allows for complete heat exchange between incoming and outgoing air. The placement of the pipe mouth affects the formation of good traction.

When placing the pipe vertically in its lower area, it is necessary to install a special receiver to collect condensate. The vertical type of chimney has more high cost, since it is more labor-intensive to install, more material is consumed to create it.

The horizontal type is the only available option for boiler equipment that can be connected in a city apartment. You can arrange such an outlet yourself, since this will require a minimum of materials. Installation is also simple; a device for collecting condensate does not need to be installed. Water will be able to flow out into the street naturally due to the negative slope of the chimney.

The horizontal option is one of the optimal ones for the corresponding boilers

Advantages and Disadvantages

The coaxial system has many advantages compared to other types of chimneys. The following advantages can be highlighted:

Clean air, which is needed for the flame to burn, moves from the street to closed system equipment. Air from the heated space is not used to operate the device.
This circuit prevents carbon monoxide or natural monoxide from entering the room. There will be no drafts in the house, the operation of the system will not affect the humidity and air temperature in any way.
Coaxial chimney increases the productivity of a gas boiler, natural gas consumption will be economical, and the amount of substances released into the environment will be reduced.
The smoke channel is reliably protected by a casing with an air gap, so there is no open contact with surrounding structures and objects.
With proper installation and operation, the possibility of fire or burns is eliminated.
The purchase and installation of a coaxial pipe will require much lower financial costs than the purchase and installation of another type of chimney.

This equipment has a lot of advantages

Such a system has only one drawback - freezing of condensate on the surface outer pipe in extreme cold. However, this is an absolutely solvable problem. The end of the chimney can be insulated with basal or mineral wool.

Some craftsmen are confident that condensate freezing can be avoided by shortening the pipe. Professionals do not advise changing the design with your own hands. Manufacturers have developed a model with a head against ice formation. It can be used to prevent freezing.

Air enters this pipe through its holes in the lower area. This invention is designed to work even in severe frost conditions. The device has a nozzle for the inner pipe, inside of which a special spiral is placed. The holes for air intake along the edge of the pipe are distributed from below.

Installation features

The horizontal type of chimney is quite easy to install, and it also takes a lot less space. To get the maximum quality work a number of requirements must be followed:

The outer pipe should be 2 meters from the ground.
Distance from pipe to doors, windows, ventilation ducts etc. vertically and horizontally should be at least 0.5 meters.
If there is a window above the ventilation hole, the distance to its lower area should be at least a meter.
There must be a free space of at least 1.5 meters under the coaxial pipe. There should be no obstacles, pillars, walls or fences at this distance.
If there is no receiver for collecting condensate, then the pipe must be placed with a slope towards the ground. Its angle should be from 3° to 12°.
It is prohibited to route the channel into any space other than the street.
If gas pipes and the chimney parts pass nearby, a distance of 20 cm should be maintained between them.

The chimney pipe can be placed under a canopy or balcony. The closer the chimney opening is located to the balcony, the longer the length of the outer part of the pipe should be. There is an opinion that with a horizontal installation scheme, the length of the chimney should not be more than 3 meters. This is not always true. Some types of equipment are 4-5 meters long.

To install a coaxial chimney with your own hands, you need to stock up on the necessary materials. The list of tools may vary depending on the situation, but most often the following devices are required:

the pipes themselves;
adapter connecting the chimney and boiler;
tee, elbow;
crimp clamps for effective fixation of parts.

Most often, all installation equipment is supplied with the chimney. To route a pipe through a roof, wall or ceiling, use fire-resistant gaskets. They are required to protect materials located near the chimney from ignition and overheating.

Installation and operation

Installation and correct connection of the system to the boiler is a simple process. To install horizontal chimney, you need to follow the step-by-step instructions:

First, you need to place the gas boiler in its place, and mark the center of the intended pipe outlet on the outside wall of the building.
Now the boiler should be temporarily removed and using a hammer drill and a cutting bit, drill a hole in the load-bearing wall. Its diameter should be 20 mm larger than the size of the outer pipe.
An adapter must be connected to the boiler outlet hole. When connecting, use a sealing gasket. Then, using self-tapping screws or self-tapping screws, attach the adapter flange to the surface of the boiler.
The pipe must be connected to the external pipe of the adapter. To create reliable fixation no sealants should be used.
Be sure to check the tightness of the connections and the fixation of the fasteners. If everything is done correctly, the pipe is inserted into the hole in the wall.
Now the boiler can be returned to its original place and mounted on the wall. The chimney must be installed with a slope of 3-5 degrees towards the street. It should be fixed in the wall with small stones.
Holes between the outer casing and the wall must be sealed with polyurethane sealant.

High-quality ventilation

Although waste substances exit through a sealed channel, and air enters from the outside, care must be taken to ensure good ventilation of the room in which the boiler is located. This will allow you to maintain ideal humidity levels in the room, which will have a positive effect on the operation of the equipment and extend its service life.

No matter how high-quality the system is, it may fail after some time. If a minor breakdown occurs in the boiler room, with good ventilation, carbon monoxide will escape naturally. In this case, the risk of gas poisoning is significantly reduced.

A coaxial chimney is a reliable, efficient and easy-to-install equipment. In order for the system to work efficiently, it is necessary to comply with the installation requirements and follow the operating instructions.

IN modern devices Various heating elements can be used. Their composition depends on the type of coolant and heating method. A mandatory component of such installations is a chimney, which is responsible for removing smoke and other combustion products from the room. Let's figure out what it is - a coaxial chimney for a gas boiler and what its advantages are. When installed correctly, such a design not only eliminates burning and smoke, but also ensures an influx of fresh air.

This is what the design for removing combustion products looks like

The design of a coaxial chimney for a gas boiler is not so complicated. It consists of two pipes of different diameters that are installed inside each other. In this case, a gap of several centimeters is left between the walls.

There are two types of similar chimneys:

collective structures are produced only in industrial conditions and are installed only at the stage construction work. The device assumes the presence of heat-insulating components;
individual options are used in everyday life and can be connected to only one heating unit.

Works coaxial installation like this: air is taken from the street through an external pipeline, then it moves through pipes and heats up. The air is supplied to the firebox already heated, which reduces gas consumption. Smoke is removed from the inside through a channel. Certain devices have an insulation system. In order for the chimney structure to work correctly, high-quality assembly must be carried out. This turns on the security nodes.

For units with chambers closed type chimneys with a length of no more than two meters are suitable. This will prevent swirls from appearing.

Useful information! The coaxial version can be installed even in wooden building, as it is perfectly protected from fire.

Related article:

Do you know why this technique is so good? In this review we will look at all the advantages and disadvantages, as well as the secrets of choosing this type of boiler

Location of the coaxial chimney system

Most often, a coaxial chimney is installed using direct passage through the wall. In some cases, the device is passed through the roof or through ceilings. The best location for such a design is horizontal. If the heater is located in a hard-to-reach place, the air duct is routed using vertical sections.

Such lines are ideal for parapet equipment and convectors. A coaxial type system with a burner can be used. Steel chimneys are suitable for double-circuit and single-circuit units. Stainless steel, aluminum or plastic are used in the production of pipes.

For your information! When selecting pipes for gas equipment, it is necessary to take into account that for individual heating devices Only designs manufactured by the same manufacturer as the main units are suitable.

Related article:

In the article we will consider design features designs, average prices, customer reviews and secrets the right choice of this type boilers .

Composition of a coaxial pipe to a gas boiler

A coaxial chimney for a gas boiler contains the following elements:

straight pipes were used to form the chimney;
A rotating element or tee is used as connecting parts. With their help, straight parts of the device are mounted to the boiler;
special area for performing maintenance work;
container for condensate accumulation;
the upper part of the structure used to protect the installation contours.

The unit is manufactured from acid-resistant stainless steel, which can withstand significant temperature increases. Chimneys are like this:

pipes without insulation have a simple structure. Such a structure must be additionally insulated to reduce condensation;
pipes with insulation are used for vertical structures. Insulated lines have excellent aerodynamic characteristics.

Important information! Many boiler manufacturers advise installing coaxial equipment with a slope towards the heating unit.

Why do you need a coaxial installation?

The most important advantage of a floor-standing gas boiler with a coaxial chimney is that the flow of fresh air allows you to maintain the combustion process. When installing such a device, you will not have problems with excessive dryness in the room. In addition, you will not have to ventilate the rooms often.

The air passing through the installation circuit warms up, thereby improving the combustion process. This contributes to greater equipment efficiency. Due to the constant flow of air, the gas in the combustion chamber is completely burned, which increases the efficiency of the system. The coaxial line does not have such a high surface temperature as a traditional chimney.

For your information! You can select a coaxial type chimney for each heating structure. There are pipes of different diameters and from different types of material. Such a device can easily be installed even by an untrained specialist.

Coaxial chimney: installation requirements and installation

Some rules for installing a coaxial chimney will help you build a high-quality heating system. Of particular importance are the step-by-step instructions:

make sure all elements are in place. In addition to the set of pipes, there must be connecting parts and various insulation materials;
before installation, you need to mark, calculate all the chimney channels and make all the necessary holes;
installation heating unit and chimney is produced simultaneously;
the exit is located one and a half meters above the combustion chamber;
the chimney line is fixed to the outlet pipe using a clamp and a pair of bolts;
the structure is assembled according to a special project;
the installation elbows are secured using clamps;
a slight slope is created on the exit section of the chimney.

Installing a chimney through a wall does not require special equipment or skills. This design is relevant for buildings with an autonomous heating system.

Such chimney elements are easy to install and also have a long service life. Under the influence of low temperature values, some areas of the chimney structure may freeze, which affects the efficiency of the entire system. Insulation will help to avoid such situations. It is important to take into account the features of a specific device when a pipe is in a pipe. An effective solution would be to reduce the cross-section of the chimney installation. You can try making the inner tube shorter. This will prevent condensate from freezing. Installation of separate steel pipes is practiced. In this case, one will take in air, and the second will remove combustion products.

In the table you can see prices for individual models.

Image	Models	Price, rub.
	Ferroli Ø 60/100 (010012X0 / KIT12X0)	1750
	Kiturami 125	4300
	De Dietrich DY 908 DN 60/100 mm (800 m)	4100
	Universal kit 60*100 (Pl) 750	3200
	Buderus 60/100 - length 810 m	2900
	Navien kit	3100

The decision to install a coaxial chimney will give good results. A useful recommendations and using the instructions will help you install such a structure yourself, without the involvement of specialists.

Coaxial chimney for a parapet gas boiler (video)

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DIY instructions and drawings of long-burning solid fuel boilers

A modern autonomous heating system consists of many elements. Its composition may vary depending on the type of coolant or the method of heating it. When heating the coolant in pipeline systems or in heat exchangers with an open fire, heating furnaces operating on various types of fuel can be used. Regardless of the combustion material, the heating boiler must provide a system for removing combustion products, or a chimney. This design can also be built in different ways. So if you have a gas heating system good elections there will be a coaxial chimney; for gas boilers they are:

wall (vertical);
horizontal (inset through the wall).

The very concept of “coaxial” involves placing one cylinder inside another cylinder. Thus, the coaxial chimney system for gas boilers consists of one pipe, which is placed inside another pipe. Thus, the system will have two circuits created from pipes of larger and smaller diameters. To ensure that the distance between the large and small pipes remains the same throughout their entire length, they are fixed with jumpers that prevent the walls of the pipelines from touching each other.

Purpose of coaxial chimney system

The main area of use of coaxial chimneys is heating systems with gas heating boilers equipped with closed furnaces for fuel combustion. It can be represented by a gas boiler, convector or radiator. The two circuits of the coaxial chimney perform different functions:

The first circuit is responsible for removing gas combustion products from the boiler furnace.
The second circuit is responsible for the flow of fresh air into the firebox, necessary for efficient combustion.

In order to ensure efficient draft and uniform combustion of gas, boilers with closed combustion chambers must be equipped with coaxial chimney systems of length not exceeding 2 meters. Otherwise, turbulences will form throughout the pipe, which will prevent the free removal of combustion products and the flow of fresh air.

Rules for placing coaxial chimney systems

The short length of coaxial chimney systems dictates strict limits for their placement. The most common installation method is direct penetration through the wall to the street. More rarely, during installation, coaxial chimney systems are observed to pass through ceilings or through the roof. A coaxial chimney pipeline works most efficiently if it is strictly horizontal. If the gas heating boiler is located in an inconvenient place for such an outlet, the outlet can also be made through the roof, using vertical sections of the structure.

Composition of the coaxial chimney structure

The standard design of a coaxial chimney for gas boilers consists of the following main parts:

Straight pipes - they form the channel of the chimney system

Connecting elements (tee or rotary section) are designed to connect straight sections and connect the chimney directly to the gas boiler. The cleaning area is intended for carrying out regular maintenance work,

A place for collecting water condensate - gas combustion products carry water vapor, which can accumulate on the walls as it cools. To prevent it from entering the combustion chamber, such a section is formed.

Upper outdoor area chimney - designed to protect the internal contours of the chimney coaxial chimney system from the effects of atmospheric conditions: snow or rain, as well as protection from the wind.

What materials are coaxial chimneys most often made from?

Industrial production of elements of coaxial chimneys for gas heating boilers is carried out from many materials:

Pipes made of stainless steel. This is perhaps the longest-living material, but such equipment has an increased price.

Galvanized steel pipes - such devices are sold cheaper, but they are more susceptible to corrosion.

In addition, various sections of the chimney, as well as external and internal pipelines, can be made of a wide variety of materials, including high-strength polymers.

What does installing a coaxial chimney provide?

The most important advantage of placing a coaxial chimney for a gas heating boiler is the fact that fresh air is taken in to constantly maintain combustion in the firebox from outside the room. In this case, you will not experience discomfort due to the burning of oxygen in the room, and you will not encounter excessive dry air. The use of coaxial chimneys will avoid frequent ventilation of the room in which the gas boiler is located. This is especially important in cold weather, because when ventilating through windows you cool the air in the rooms, and heating back up requires increased consumption of coolants and energy.

In addition, the air entering along the contour of the coaxial chimney, when moving from the street into the combustion chamber, heats up, which facilitates the combustion reaction and increases the efficiency of your gas boiler. With a constant supply of fresh air heated to room temperature, the gas in the furnace of your boiler is completely burned, significantly increasing the efficiency of the entire heating system.

It is worth noting that complete combustion of fuel also increases the environmental friendliness of the heating system - you do not pollute the surrounding air with unburned elements.

Also, combustion products, when passing through the exhaust circuit, give up part of their heat to fresh air coming from outside. This reduces the risk of fires inside the pipe in areas with an accumulation of unburned particles. The coaxial pipe has an outer surface temperature that is significantly lower than a classic chimney, which reduces the fire safety requirements for its installation. Thus, coaxial pipes (with appropriate insulation, of course) can be passed through wooden walls or overlap, which is impossible for a conventional steel chimney. A gas heating system with a coaxial flue exhaust creates a completely closed fuel combustion circuit, in which oxygen for constant combustion is taken from the street air and combustion products are discharged there. This creates comfortable atmosphere in the room where the gas heating boiler is located. This is important, since gas water heating boilers are often located in habitable areas, for example, in kitchens.

Wide range

Selection of a coaxial chimney is possible for almost any gas heating system, regardless of its power: pipes of the most different diameters made from a variety of materials. Installation of such a system is relatively simple and can be easily performed even by an untrained specialist.

Installation of a coaxial chimney

Please note that improper construction or installation of a coaxial chimney system can negate all its advantages. For correct installation follow the step by step instructions:

Make sure you have all the necessary materials and tools. To do this, you will need a set of coaxial pipes and connectors, wall trim to form a seal, and an outdoor ferrule.
Before proceeding with installation, make markings, calculate the path of the chimney, remove unnecessary objects, and make a hole of the appropriate diameter in the wall. When designing the installation, make sure that there are no flammable objects near the pipe.
The best choice would be to simultaneously install a gas heating boiler and a corresponding coaxial chimney.
The chimney outlet should be located approximately a meter and a half above the level of the gas combustion chamber. To achieve optimal location the chimney system can be lengthened, but installing more than two elbows in it will lead to the formation of turbulence with a sharp decrease in its efficiency.
The coaxial pipe is connected to the outlet pipe of the combustion chamber of the gas boiler using a clamp. It is fixed with two bolts.
After this, we assemble the chimney system in accordance with the designed configuration.
The chimney elbows are also secured to each other using clamps.
At the outlet section of the chimney, we form a slight downward slope, so that condensing moisture is removed from the system by gravity.
A protective weather vane can be placed on the upper outer part of the coaxial chimney.

We insulate the coaxial chimney

At low negative temperatures outside, some sections of the coaxial chimney may well freeze, which negatively affects its efficient work. In order to avoid negative aspects, such areas must be insulated. This would seem to be a reasonable solution, but the “pipe-in-pipe” design itself negates any insulation.” Instead the best way out there will be a reduction in the cross-section of the chimney system. If frost is observed on the chimney head, try making the inner pipe of the system shorter. In this case, condensate freezing can be avoided. In extreme cases, it is practiced to install two separate steel pipes, one of which takes in air, and the other removes combustion products.

Coaxial chimney for a gas boiler video

Heating equipment operating on solid or liquid fuel requires the installation of a complete system for removing combustion products. Previously, a classic chimney made of single-walled steel pipes was used as an exhaust device, which has a lot of disadvantages. Nowadays more practical and effective solutions based on a coaxial pipe.

What is a coaxial chimney

The concept “coaxial” is used to designate any structure consisting of two objects located around a common axis. In the case of a coaxial type chimney, this is a smoke exhaust channel consisting of pipes of different sections.

The distance between the pipes is the same along the entire length of the chimney, including rotary elbows, bends and other elements. This is achieved through special jumpers, which are located along the entire length of the chimney.

The coaxial chimney is made of two pipes with a common central axis, separated by special internal jumpers

The principle of operation of a coaxial chimney

The channel between the inner and outer pipes ensures a constant supply of fresh air, which is necessary to maintain combustion processes. The inner pipe is a channel for removing flue gases and other combustion products. In fact, the special design of the coaxial pipe allows the chimney to perform two functions at once: output harmful substances and supply ventilation.

Flue gases are removed through the internal channel, and fresh air enters the combustion chamber through the inter-tube space

The main area of application of coaxial chimneys is wall-mounted and floor-mounted gas boilers with a closed combustion chamber, geysers and convectors. With equipment running on solid fuel, coaxial type chimneys are not used.

Advantages and disadvantages of the coaxial chimney design

Among the advantages of coaxial type chimneys are:

Despite many advantages, the design of a coaxial pipe is not without drawbacks. At temperatures below -15 o C, the coaxial chimney can freeze severely.

This is due to the fact that, in fact, this is an advantage of the design in question - the cold air is heated due to the temperature of the flue gases escaping outside. The combustion products cool greatly and can condense at the outlet of the chimney, which leads to severe icing on the chimney head.

One of the main advantages of a coaxial chimney turns into its main disadvantage - at low temperatures outside, combustion products condense and ice freezes on the pipe head

To prevent icing, you should choose special devices designed to operate under negative temperature, and also more carefully calculate the cross-section of the chimney.

Types of coaxial chimneys

Depending on the method of laying the chimney, coaxial type chimneys are divided into two types:

Vertical - the chimney is located strictly in a vertical position. Gases and combustion products rise from the fuel chamber and are released into the atmosphere above the ridge level. Mainly vertical structures are used in residential buildings and provide a good level of natural traction.
Horizontal - the main chimney channel is represented by a structure located in a horizontal position, which is discharged through load-bearing wall. In this case, flue gases come out in the immediate vicinity of the heating equipment. It is most often used in private homes where closed heating systems are installed.

A vertically oriented coaxial chimney, despite some advantages, is a more expensive and difficult to install system. The total length of the smoke exhaust duct usually exceeds 5 meters, which significantly complicates the process of installation and fixation of the structure.

To manufacture a coaxial type chimney, various grades of steel and plastic are used. In accordance with this, several types of chimneys can be distinguished:

galvanized - the most affordable option for a coaxial type chimney. Average term The service life of the product does not exceed 5–7 years, after which the structure partially rusts or becomes damaged. The cost of the product depends on the manufacturer and technical parameters, but rarely exceeds 2–2.5 thousand rubles;
made of plastic and aluminum - combined option for private use. The internal chimney channel is made of aluminum up to 2 mm thick. The outer pipe is made of high-strength heat-resistant polypropylene. Such chimneys are used only in the private sector to work together with boilers of low and medium power;
Coaxial chimneys made of galvanized steel are designed to last 5–7 years, plastic products will last much longer
stainless steel chimneys are more reliable and durable than galvanized ones. They are designed for 10–12 years of use. The cost is almost the same as stainless steel products. They are not used in industry and collective smoke exhaust systems, since “stainless steel” does not withstand high concentrations of chemicals;
made of high-alloy steel - the most durable and durable option for a coaxial chimney. High-alloy steel is not afraid of exposure to high temperatures and chemicals contained in flue gases. The average service life is at least 15 years.
A coaxial chimney made of high-alloy steel, unlike stainless steel, is not destroyed by aggressive chemicals contained in combustion products and lasts at least 15 years

The range of some manufacturers (Electrolux, Viessmann, Schiedel) includes models of coaxial chimneys with an additional thermal insulation layer. This is a classic design with two channels, which is located in another pipe. The voids between the outer pipes are filled with non-flammable thermal insulation material, preventing freezing and blockage of the air channel.

Video: coaxial pipe for parapet gas boilers

Basic elements of a chimney

A coaxial chimney consists of various elements that make it possible to produce a chimney of the desired configuration for specific operating conditions and structural features.

The coaxial chimney kit contains everything needed for its installation.

Fitting, connecting elements, nozzles and other structural elements are manufactured according to a certain standard, which simplifies the process of assembling and installing the chimney. The range of leading manufacturers includes more than 80 elements of various configurations.

A ready-made coaxial chimney kit from the manufacturer includes the following elements:

To ensure the tightness of all connected parts of the structure, special sealing rings made of heat-resistant material (thermoplastic) are used. When heated to high temperatures, the ring expands into a more elastic form, which allows it to maintain a seal even at high pressure.

Making a coaxial chimney with your own hands

In order for the chimney to cope with its tasks throughout its entire service life, it must be correctly calculated and correctly installed.

Calculation of chimney parameters

When designing a chimney, special attention should be paid to calculation operations, since the performance of the system as a whole will depend on the parameters of the chimney. The cross-sectional area of the outlet channel of the coaxial chimney should not be less than the cross-section of the connecting pipe of the heating equipment.

The cross-section of the smoke duct of the coaxial chimney is selected to match the dimensions of the heating equipment pipe

In collective systems, when connected to two or more heating devices, the channel cross-section increases in proportion to the size of their pipes. This is necessary in order to ensure sufficient throughput smoke exhaust duct during simultaneous operation of several boilers.

Table: dependence of the cross-section of the chimney channel on the rated power of the heating device

The cross-sectional diameter of the outlet hole is calculated by the formula - F = (K * Q) / (4.19 * √H), where:

K - constant coefficient equal to 0.02–0.03;
Q (kJ/h) - maximum power of the gas boiler specified in the device specification;
H (m) - design height of the smoke channel.

For example, let's calculate the cross-section of the chimney outlet for the Ariston CLAS B gas boiler. The maximum thermal power in heating mode is 24.2 kW. The height of the smoke channel is 8 m.

To convert power from W to kJ/h, we will use one of the online programs that are easy to find on the Internet. We get that Q = 87 120 kJ/h.
We find the cross-sectional area using the above formula: F = (0.02 * 87,120) / (4.19 * √ˉ8) = 147.03 mm.

After calculations, the resulting value must be compared with the data in the table. It indicates optimal area chimney sections round section for domestic gas boilers. If necessary, the value is adjusted up or down. In our case, you can use a pipe with a diameter of 130 mm.

Necessary tools for installing a coaxial chimney

To install a ready-made coaxial chimney kit you will need:

For self-made a coaxial chimney will require two pipes of a suitable diameter, which are connected using stainless steel jumpers. Steel rivets or self-tapping screws are used for connections.

It is important to understand that completely repeat the design of finished chimneys industrial production it won't work. You can only make a straight section of coaxial pipe yourself.

Preparatory work before installing the chimney

According to statistics, coaxial type chimneys are the safest. The rules for their assembly and installation are described in detail in SNiP 2.04.08–87, SNiP 2.04.08–87 and PB 12–368–00. Before installing the chimney, you should carefully study the attached instructions and become familiar with the requirements outlined by the manufacturer of the structure.

In general, when installing a coaxial chimney, the following rules must be observed:

When installing a coaxial type chimney in wooden houses, the place where the pipe meets load-bearing wall or the ceiling is sheathed with non-combustible material. Usually an asbestos pipe or a box made of asbestos-cement slabs is used.

Step-by-step instructions for installing a coaxial chimney

Before installing the chimney, you should carefully check the completeness of the purchased device. If any parts are missing, the chimney assembly should be postponed. In addition, it is imperative to check the diameter of the outlet pipe and the cross-section of the internal channel.

The technology for assembling a coaxial type chimney consists of the following steps:

In the designated location, markings are applied for the exit of the smoke duct to the street. For a floor-standing gas boiler, the chimney outlet should be located 1.5 m above the combustion chamber. For wall-mounted installations, it is possible to remove the pipe immediately after installing the rotary elbow.
The chimney of a wall-mounted boiler can be removed immediately after installing the rotary elbow on its pipe
After applying the markings, using a hammer drill with a crown attachment, a hole of the required diameter is drilled at an angle of 3° to the wall surface. It must be taken into account that in addition to the pipe, an insulating gasket is installed in the hole.
An adapter is connected to the outlet pipe of the gas boiler, onto which a straight section of pipe or a 90° coaxial elbow is mounted. To connect the elements, a crimp clamp is used, which is tightened with a Phillips screwdriver.
A special adapter is used to connect the chimney to the gas boiler
An asbestos pipe and a sealing collar are installed in the wall hole. Next, the straight section of the chimney is led outside. From the inside, the pipe is connected to a rotary elbow or extension nozzle and secured with a crimp clamp.
The hole in the wall is additionally insulated using special pads. To do this, the contact point is treated with heat-resistant sealant, and the nozzle is screwed onto galvanized screws. If necessary, a deflector or blow-out protection is placed on the end of the pipe.
The deflector protects the boiler from blowing out through the chimney

When installing a vertical structure, a hole in the ceiling is cut using a grinder with a wood saw. A box of asbestos-cement slabs is installed at the junction point. In this case, the distance from the outer pipe to the ceiling should not be less than 20 cm.

A similar condition is met when the pipe exits through the roof. To do this, a special passage element is mounted at the junction point, which is attached directly to the roofing material using galvanized screws.

Video: coaxial chimney in a private house

Chimney insulation

Freezing and icing of the head of a coaxial chimney is associated with condensate entering the air intake duct. To prevent moisture ingress, you should check the slope of the coaxial pipe relative to the combustion chamber. If the slope angle is at least 3 o, then freezing of the tip will only occur at temperatures below -15 o C.

The main mistakes when installing a chimney are related to incorrect inclination of horizontal sections

Additionally, a special element can be installed on the head, which extends the internal channel by 10–40 cm relative to a pipe of larger diameter. In addition, several holes can be drilled in the lower part of the outer pipe. This will allow air intake even when the tip is partially frozen.

If the slope is insufficient, freezing cannot be eliminated, since the condensate will not flow towards the combustion chamber, but, on the contrary, towards the outlet, which will lead to the formation of icing and icicles at the end of the pipe. Insulation by covering with heat-insulating material with outside pipes won't help.

Video: removing condensation from the air supply pipe in winter

Chimney cleaning and periodic repairs

For operation of heating equipment with a closed combustion chamber, it is used natural gas- methane. During the combustion of gas, harmful aromatic hydrocarbons, toluene, benzene, etc. are formed. The formation of soot and burning does not occur as such.

Almost all gas combustion products are discharged through a coaxial chimney. At the same time, complete cleaning of the smoke channel is not required even with daily use. It is enough to check and clean the condensate collector once a heating season. Once every few years, it is recommended to inspect the smoke duct using special video inspection equipment.

A highly sensitive thermal imager is used to inspect and inspect the chimney

To repair a chimney, you will need to dismantle all elements of the smoke exhaust channel down to the damaged area. After replacement, the structure is assembled taking into account regulatory requirements.

The coaxial chimney is a highly efficient and practical design that significantly increases the efficiency of heating equipment. Subject to the rules described in regulatory documents, a coaxial chimney does not require periodic repairs and reliably removes all flue gases.