Gas boiler chimney: standards and installation requirements

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If gas is selected for heating in the house, care should be taken to remove combustion products. This means that you need to choose and properly install the chimney for the gas boiler. Compliance with the rules and regulations in this matter should not be categorically neglected, since this may call into question not only health, but also the life of the residents of the house.

We are ready to share with you useful information about the rules of installation and connection of the chimney for a gas unit, the specifics of the selection of the optimal design. Information is complemented by visual illustrations and video instructions.

The content of the article:

  • Why do you need a chimney?
  • The subtleties of the design of the smoke channel
    • Rule # 1 - Compliance with the channel cross section
    • Rule # 2 - Ensuring Anti-condensate
    • Rule # 3 - Choosing a Sectional Shape
    • Rule # 4 - Performing Dips, Turns, Ledges
    • Rule # 5 - Correct Pipe Connection
    • Rule # 6 - the details of the location of the pipe on the roof
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  • Chimney for two boilers
  • Selection of materials for construction
  • Preliminary calculations and device
  • Conclusions and useful video on the topic

Why do you need a chimney?

One of the most dangerous products formed during virtually all types of combustion is carbon monoxide. This insidious and very dangerous substance, the inhalation of which threatens severe forms of poisoning.

During the operation of a gas boiler in the process of combustion of fuel, in addition to other products of combustion, carbon monoxide is formed.

If the chimney, which removes combustion products, is installed incorrectly or damaged, it can lead to poisoning.

Chimney for gas boiler

This diagram shows the chimney device for a gas boiler and reflects its location inside or outside the building.

Danger should not be underestimated. Carbon monoxide (carbon monoxide) is odorless and colorless, so poisoning can occur completely unnoticed by anyone in the house.

Once in the human body, carbon monoxide molecules interact with hemoglobin. As a result, the so-called carboxyhemoglobin is formed, which prevents the entry of oxygen molecules into the tissues of the human body.

In addition, carbon monoxide can very badly affect other biochemical processes in the body. There were cases when carbon monoxide poisoning was detected too late, the person simply could not be saved.

To avoid such problems, it is recommended to pay the closest attention to the correct chimney design and installation, as well as its further maintenance.

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Gas equipment chimney

In the device of chimneys for gas boilers, the rules and regulations are regulated by the SNiP 41-01-2003 collection

Certified chimney structures and elements

Ready-made structures, prefabricated structures and elements used in the construction of chimney channels are subject to mandatory certification.

Metal chimney structures

In the construction of chimneys and production of elements for the assembly are used exclusively non-combustible materials.

External circuit of the chimney

In the construction of smoke channels for gas units are used both internal and external layout of the main part of the chimney

Laying coaxial chimney in the boiler room

The installation of gas boilers and the installation of smoke pipes in non-residential premises of private houses are recommended.

Connecting the chimney to the collective channels

In multi-family houses, the gas spouts are connected to collective smoke channels.

Tight connection of the smoke channel

Elements of the smoke channel must be connected tightly and regularly monitor the quality of the connection.

Gas alarm devices in the room

In rooms with gas equipment, it is recommended to install devices that signal if gas is released into the environment.

Gas equipment chimney

Gas equipment chimney

Certified chimney structures and elements

Certified chimney structures and elements

Metal chimney structures

Metal chimney structures

External circuit of the chimney

External circuit of the chimney

Laying coaxial chimney in the boiler room

Laying coaxial chimney in the boiler room

Connecting the chimney to the collective channels

Connecting the chimney to the collective channels

Tight connection of the smoke channel

Tight connection of the smoke channel

Gas alarm devices in the room

Gas alarm devices in the room

The subtleties of the design of the smoke channel

With chimney design value has everything: its size, configuration, section, and slope, and other parameters. The following describes a series of guidelines that are recommended to consider first.

Rule # 1 - Compliance with the channel cross section

The cross section of the chimney duct over the area should be not less than the cross section of the gas boiler pipe with which the device is connected to the chimney.

If two devices are connected to the chimney at the same time, the cross section should be increased, taking into account the probability of simultaneous operation of two devices. Those. the channel section must be equal to the total size of the pipes of both units of equipment.

Rule # 2 - Ensuring Anti-condensate

Modern gas boilers are designed so that the maximum amount of heat is supplied to the heat exchanger. Such high efficiency contributes to the production of combustion products with a relatively low temperature.

As a result, moisture is formed on the walls of the chimney. An increased amount of condensate that includes corrosive substances can have a detrimental effect on the integrity of the walls of chimneys.

Tee for chimney

To connect the gas boiler to the chimney construction use a special tee on which a device for collecting condensate is mounted

To protect the structure, it is recommended not only to lay out the chimney from a brick, but also to perform its sleeveing, insert a special stainless steel pipe inside. Such pipes are durable and resist corrosive well.

An alternative solution for dealing with condensate may be lining, i.e. installation of a special flexible chimney. To collect the condensate using a special container. It is installed just below the place where the boiler pipe is connected to the chimney.

Rule # 3 - Choosing a Sectional Shape

The traditional cylindrical shape of the chimney is considered optimal for the effective removal of combustion products. In addition, in such a chimney it is easier to perform preventive cleaning.

Chimneys with an oval cross section are considered quite acceptable, although not as convenient. Square designs also have the right to exist, but the indicators of thrust in them are usually reduced.

Rule # 4 - Performing Dips, Turns, Ledges

Optimal for floor gas boiler It is considered a vertical chimney that does not have ledges. In practice, to achieve such an arrangement of the structure is not always possible.

Deviation from the vertical is allowed no more than 30 degrees. At the same time, it should be ensured that the dimensions of the cross section of the inclined section comply with regulatory requirements.

At the same time, the pipe itself connecting the chimney and the boiler must include a strictly vertical section with a height of half a meter or more. Of course, if necessary, you can make some parts of the chimney horizontal, but they should not be too much.

Chimney slope

When installing a chimney construction for a gas boiler, it is possible to have inclined sections, the slope must be 60 ° or more degrees relative to the horizon, the inclined section length is up to 1 m

For example, if the height of the room in which the chimney is installed is about three meters, then the total length of the horizontal chimney segments should not exceed these dimensions.

Although, as mentioned earlier, the closer the design of the chimney to the vertical, the better. It is not allowed that the chimney slope in the direction of the boiler is more than 0.1 degrees. As for the turns of the chimney construction, their maximum number is three turns, not more.

Rule # 5 - Correct Pipe Connection

To connect the individual parts of the chimney construction use special clamps. The slope of the chimney knee can be 15-90 degrees. A certain distance should be maintained between the connecting pipes and other surfaces.

It depends on what materials these surfaces are covered with. In places where combustible or even fireproof materials are used, it is recommended to maintain a distance of at least 25 cm.

The distance from the surfaces covered with fire-resistant materials should be at least 5-10 cm. To protect the chimney from flammable materials using asbestos board, brickwork, etc.

Chimney Fastening

When installing a chimney for a gas boiler, all its elements must be securely fastened, maintaining the correct pitch between fasteners

Particular attention should be paid to the joints of individual segments of the chimney structure. They must be made of durable materials that do not bend under external influence.

The same characteristics should have all the fastening elements of the chimney. Horizontal or sloping chimney should not be under load.

The elements of the chimney are inserted into each other at a depth that is equal to half the diameter of the pipe or exceeds this figure. No gaps in these places are unacceptable, the connection must be tight and tight.

In case of violation of the tightness of the connection of individual elements of the chimney, carbon monoxide can quietly enter the room. Therefore, the condition of the chimney should be checked periodically, and in all rooms where chimney pipes are laid, good ventilation should be organized.

Rule # 6 - the details of the location of the pipe on the roof

Chimneys should rise above the ridge of the roof by 50 cm or more, and the distance from the edge of the parapet to the chimney should be no more than 150 cm. If the axis of the chimney is located at a distance of 1-1.5 m from the roof ridge, then it should rise 50 cm or more above the ridge level.

Distance to chimney

This diagram clearly demonstrates how, in accordance with technical standards, determine the height of the chimney relative to the ridge of the roof so that it does not prevent the formation of thrust

If labor is still further from the ridge, then it can be made the same height as the ridge. The pipe may be even lower if it is separated from the ridge of the roof by a distance of more than three meters.

In this case, you need to draw a conditional line down from the ridge at an angle of 10 degrees to the horizon. The height of the chimney should reach this mark. It turns out that the further the pipe is located from the ridge, the less should be its height relative to the ridge of the roof.

There is no chimney on the flat roof, therefore, in accordance with the standards, a chimney pipe 100 cm high is erected. On the combined roof, the chimney height should be about two meters.

Basalt shell

The chimney section, located above the roof and within the unheated attic, is necessarily insulated to improve the draft and prevent condensation. One of the options for such insulation - basalt shells

The outer part of the chimney must be warmed. If we neglect this moment, condensate will accumulate on its surface. Moisture can penetrate inside the chimney, leading to the development of corrosion processes and damage to the structure.

The part of the chimney structure, which is located on the outer side of the house, also needs warming. Insufficient insulation can also reduce the efficiency of the chimney, reduce its cravings.

If it is not possible to bring the chimney through the upper slab and roof, use coaxial chimneys. This option can be brought out through the wall, while the intensity of removal of the products of combustion of blue fuel is not reduced.

Chimney for two boilers

If the house has not only a gas boiler, but also other heating or water-heating equipment, the following standards should be considered:

  1. No more than two such devices can be connected to one chimney, located on the same floor or on different floors.
  2. In this case, the openings for the discharge of combustion products for these devices should be at different levels.
  3. Entrances to the chimney should be separated by a distance of 50 cm or more.
  4. Entering the combustion products from two devices at the same level is allowed only if there is a special dissecting insert inside the chimney.
  5. At the same time, the height of the parallel inlets into the chimney, equipped with a divider, must be at least one meter.

Of course, the construction of several chimneys will cost more than just one design, but you should not neglect the requirements of building codes and safety rules for the sake of questionable savings.

Chimney Requirements for Gas Boiler

Construction standards allowed the option of connecting two heating units to one chimney channel. In such cases, a slit thickness of 12 cm is arranged at a height of 1 m from the lower point of pipe connection

When creating a chimney should not use materials with low density and high porosity, which is different foam and cinder blocks. Chimney should not pass through the accommodation.

It is not allowed to install such structures also on closed loggias or balconies. In all rooms where there is a chimney, it is necessary to organize proper ventilation.

Chimneys of boilers that process gas into heat energy, mainly of mounted type. According to the mounted scheme, the channel is installed directly on the slab of the heating unit. However, it is permissible to connect to wall chimneys through pipes no more than 40 cm long.

In the case of connection to the wall chimney, a gap of 14 cm should remain between the lower line of the nozzle and the fire covering. It is necessary to leave 50 cm between the upper line of the nozzle and the combustible ceiling, if there is no fire protection, 40 cm, if there is protection.

The passage of the chimney gas boiler through the fuel ceiling

The passage of the chimney through a combustible structure is equipped with non-combustible insulation materials or devices like sandboxes

There are differences in the arrangement of the intersection of chimney flammable and non-flammable building structures. The passage of the chimney through the non-combustible structure is provided with a mounting support.

The area of ​​intersection of flammable ceiling is equipped with a box with sand or a seal made of non-combustible insulation.

Selection of materials for construction

At the device gas heating country house and the chimney for a gas boiler should use only very durable materials that are resistant to many external factors. They must be fire-resistant, capable of contact with moisture and acids released during the combustion of gas and deposited on the walls of the chimney in the form of condensate.

At the same time, the material should not be too heavy, since such a structure creates an additional load on the walls and foundation of the house.

Stainless steel flues are considered the best choice. They are exceptionally resistant to many types of corrosive effects, have a relatively small weight and provide excellent traction.

Stainless steel chimney

Lightweight stainless steel chimney construction allows for installation on their own. Moreover, the installation of such a chimney is not too complicated, since the individual structural elements are sold as ready-made modules.

The life of the chimney made of steel is usually about 15 years. But galvanized steel with the abstraction of combustion products copes much worse than stainless steel. Wet and hot evaporations with high acidity quickly destroy this material. Galvanized chimney will have to be replaced in five years.

Ceramic chimneys, which can last up to 30 years, are distinguished by their exceptionally long service life. Models of European production with an external contour from steel are especially popular and convenient. But this option has a number of serious drawbacks.

For a start, this is a relatively high weight of the structure, which should be correlated with the bearing capacity of the foundation and walls of the house. To the installation of ceramic chimney increased requirements.

It is believed that for maximum thrust ceramic chimney should be located strictly vertically, and such a configuration is not always convenient.

Coaxial chimney - the choice of highly efficient, modern, but expensive. The design of this chimney is two pipes nested in each other. Combustion products are discharged through the inner tube, while the outer one is designed for air supply.

Coaxial chimney is also supplied in the form of modules, which facilitates its assembly and installation. Another advantage is enhanced security. This, of course, if the installation process is respected coaxial chimney installation rates and building rules.

Coaxial chimney

Coaxial chimney structures are highly efficient, safe and relatively easy to install. They are suitable for removal of combustion products of gas heating units.

A classic brick chimney is not the best option for a gas boiler. A massive structure usually does not have a good load; it weighs too much, but serves only a short time. Clean such a chimney often, there is a lot of condensation on its surface, so its life when used with gas equipment is small.

Brick chimney

When arranging a brick chimney, it is recommended to perform its sleeveing: it is inserted into the body of the brickwork special steel liner liner, the smooth walls of which contribute to the removal of combustion products and prevent accumulation sediments

But if the house already has an old brick chimney, it is quite possible to use it. A special stainless steel insert is inserted inside the structure, and the brickwork becomes a protective case. Of course, the diameter of the liner and its configuration must comply with the standards described above.

Occasionally chimneys from asbestos-cement pipes can still be found, but they are supplanted by more efficient materials. Such constructions are not safe, they can break in case of overheating. The term of operation does not exceed five years. Sometimes these chimneys are installed in country houses, where the boiler is extremely rarely turned on.

All options for chimneys for gas equipment recommended to equip deflectors, with varieties and installation rules which will be introduced by our recommended article.

Preliminary calculations and device

The design of any chimney consists of various elements. Here is a sample list of chimney parts that can be installed with a gas boiler:

  • an adapter connecting the boiler pipe to the chimney structure;
  • a tee with an inspection hole and a fitting designed to collect condensate;
  • clamps for connecting individual elements of the chimney;
  • brackets and other fasteners;
  • conical tip;
  • telescopic tubes;
  • elbows;
  • feedthrough, etc.

It should be remembered that bends are usually recommended to be installed at a distance of no more than two meters from the gas boiler nozzle. This will ensure the most effective traction.

Elements of the gas boiler chimney

Separate elements of the chimney construction for the gas boiler can be purchased in finished form. The main thing is to correctly calculate the size of the structure and comply with safety requirements.

For proper installation of the chimney, it is recommended to first calculate the cross-sectional area of ​​the outlet. In this case, use the formula:

F = (K ∙ Q) / (4.19 ∙ √ˉ H),


  • K - a constant coefficient, its value varies in the range of 0.02—0.03;
  • Q - the performance of the gas boiler, as indicated in the technical passport of the device;
  • H - the estimated height of the chimney.

After the cross-sectional area has been calculated using this formula, it is necessary to compare the data obtained and correct them if necessary.

For example, according to the requirements for a gas boiler chimney, for round structures, the recommended cross section depends on the power of the boiler and can leave:

  • 120 mm for a 24 kW boiler;
  • 130 mm - for 30 kW;
  • 170 mm - for 45 kW;
  • 190 mm - for 55 kW;
  • 220 mm - for 80 kW;
  • 230 mm - for 100 kW.

If a chimney with a rectangular section is mounted, the thermal capacity of the gas equipment is taken into account:

  • for devices with a capacity of less than 3.5 kW - 140x140 mm;
  • for devices with a power of 3.5-5.2 kW - 140Х200 mm;
  • for devices with a power of 5.2-7.3 kW - 140Х270 mm, etc.

If asbestos-cement pipes are used, the cross-section of the chimney channel must be at least 100 mm. The vertical sections of the chimney are fixed on the wall with a pitch of 2.5 m, and in areas with a slope the pitch should be more often - 1.5 m.

Round chimney pipes

Chimneys for a gas boiler may have a round or square section, but the dimensions of such a section must comply with the established standards.

About, which pipe is better to choose for the construction of the chimney, will tell the next article, with the content of which we recommend to read.

Conclusions and useful video on the topic

Video # 1. A detailed overview of the installation of a coaxial chimney, designed for a gas boiler, can be viewed in this video:

Video # 2. Here is useful information on how to choose a chimney, while avoiding common mistakes:

Video # 3. Video about eliminating violations of the chimney installation technology for a gas boiler:

Mounting chimney construction is technically relatively uncomplicated. It is necessary to design the chimney, and then correctly connect and fasten its elements. But at the same time, it is important to comply with all construction requirements and standards so that hazardous products of combustion are released into the atmosphere and do not enter residential areas..

There were questions about the device and installation of chimney for a gas boiler, there are comments to the material, want to share your experience in the field of arrangement of the smoke channel with your own hands? Please write comments in the box below the text.

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