26.10.2017
2669
Pechnik (Moscow)

The diameter of the chimney for a gas boiler is one of the main values, the calculation of which must be made by a professional or taking into account generally accepted standards and fire safety requirements. After reading this article, as well as familiarizing yourself with the photo selection presented by us, you will be able to perform all the necessary calculations with your own hands, without the help of a professional.

Stages of calculations

Calculation of the chimney diameter for a gas boiler is carried out in several stages, which you can find out in more detail in the table below:

Stagedness	Detailed Descriptions
Performing installation and marking	Calculation of the chimney diameter for a solid fuel boiler or gas equipment is carried out before any installation and installation work is performed. Markings must be applied only in accordance with previously drawn up instructions or drawings. Also find out about that. What cross-sectional size the chimney should have can be found in the technical documentation supplied with the heating boiler. Also, surface markings are applied taking into account such criteria as the height and dimensions of the system. The internal part of the structure includes the roofing pie and various ceilings. External ones are external walls and a coaxial type chimney system.
	The calculation of the chimney for a solid fuel boiler should be correctly displayed at the cutting stage. Surely you will need to make cuts and create various openings in the walls and ceilings of the house.
Correct connections	The correct dimensions of the chimney for a gas boiler allow various elements and fittings to be easily connected and mated together. Thus, the adapter, or otherwise the adapter, must be connected to the pipe. Also, any design consists of elements such as revisions and tees. The space between the ceilings is supplemented with special pipes, and all joints and connections are reinforced and secured with clamps, the pitch of which is about two meters. For additional fixation, the structure is also reinforced with brackets, the distance between which should not be more than four meters.
Product of insulation	The price for installing and assembling a chimney system is quite high, since during the work it is necessary to take into account a lot of nuances and rules. At the last stage, you need to secure the correct assembly and calculations by performing insulation. To do this, choose only fireproof, environmentally friendly materials.

Things to consider

Without knowing what chimney diameter for a solid fuel boiler you should choose, you first need to familiarize yourself with the basic requirements for such exhaust systems and be sure to take them into account in the future:

1. The basis is taken from the requirements and rules specified and described in SNiPs;
2. The chimney system must have its own individual channel, through which all combustion and decay products will be removed. If necessary, you can simultaneously connect several devices to it. The distance between them should not be less than 75 centimeters;
3. Pipes must have perfect tightness. Gas should not pass through small openings and enter the room. That is why the use of a brick chimney for gas equipment is unacceptable;
4. The selected material must be able to withstand regular exposure to moisture (condensation), which is formed as a result of sudden temperature changes, especially in the winter;
5. The system must have a perfectly smooth surface of the internal walls, with a minimum amount of roughness and irregularities. The best section is round.

Important:calculating the height of the chimney of a gas boileris made taking into account the design features of the house itself, as well as the power and functionality of the heating equipment. No less important is the presence of a thermal insulation layer. This promotes rapid and uniform heating of the pipes, as a result of which the amount of condensate formed is significantly reduced.

The instructions, which are used as a basis by all professionals, say that the channel must have a cross-section equal to the gas exhaust pipe. If the cross-section of the output element has a diameter of 17 centimeters, then the pipe itself should have a similar size.

An illustrative example:chimney diameter for boiler donwill be determined as follows. It is important to take into account such an indicator as the cross section, which must be measured in square centimeters orF.

To make calculations we use the universal formula:

F = ( K∙Q) / (4.19 ∙ √H)

Explanation:

• The K number is equal to a numerical value from 0.02 to 0.03;
• The numerical value of the Q indicator (performance) can be found in the technical documentation supplied with the boiler equipment;
• H is the height of the chimney system.

Basics of operation and functioning of various exhaust devices

The final final value must be adjusted in accordance with established and generally accepted standards and fire safety requirements. To familiarize yourself with them, it is recommended to go to the appropriate website or watch the video in this article.

For brick systems, it is important to take into account that the section size is half by half brick. For chimneys made of asbestos cement (not recommended!), the diameter will be about 100.00 mm.

Installation of a chimney with an open system

For this variation, we recommend choosing a coaxial exhaust mechanism. It features simpler installation. However, one should take into account the fact that the outlet pipe must have smaller dimensions (diameter) than the pipes of the structure themselves.

Basic criteria and rules for performing installation work:

• Coaxial type systems are located in a strictly horizontal direction (more about: horizontal chimney);
• The distance from the pipe to ground level must be at least two meters;
• The installed hood is installed as far as possible from the windows, doors and ventilation ducts of the house. The optimal safe distance is 1.5-2.5 meters (from the horizontal element);
• The minimum length of a vertical section is 1-1.5 meters;
• Do not place the chimney in such a way that there are other buildings, walls, barriers, fences nearby (the minimum distance to such objects should be 1.5 meters);
• The exhaust system should not extend into an arch, tunnel or passage;
• To ensure that condensate does not accumulate in large quantities in the structure and is able to gradually flow down, the pipes are installed at a slight inclination (from 5 to 14 degrees).

Installation of an open structure

Before installation, you must familiarize yourself with the basic standards and requirements for it:

1. Installation should be as simple as possible, with a minimum number of elbows (3 pieces) and bends;
2. For insulation and assembly of the device, exclusively non-flammable materials are used;
3. To reduce the amount of accumulated condensate, the inner surface of the pipes must be insulated with special heat-insulating materials;
4. For subsequent maintenance and convenient removal of soot and soot from the inner surface of the pipes, provide in advance for the presence of a special damper in the chimney design;
5. Condensate is also collected in a collection tank specially equipped for these purposes;
6. Compare the required height and diameter of the pipes with the recommended values ​​​​specified by the manufacturer in the instructions for the heating boiler;
7. All areas must be vertical, tilting no more than 25-35 degrees is allowed;
8. The upper part is complemented by a special protective umbrella; it does not allow dirt and precipitation to penetrate inside the installation;
9. For a standard curved roof, the height of the chimney above the ridge level should be about 500-800 centimeters. For flat roofs, this figure increases to 2-2.5 meters.

The height of the pipe above the roof level must be determined individually

Tip: if you want to insulate a chimney yourself, we recommend using one of the following materials to choose from: bricks, asbestos cement, lime mortar. In addition, carefully seal each joint and connection of pipes so that gas does not enter the room under any circumstances!

Several construction options:

• Use of bricks. Not the most suitable option in this situation. Brick does not tolerate contact with the resulting combustion products and soon begins to collapse, the structure loses its tightness. The option is not durable and has a high degree of safety;
• Steel pipes. Steel tolerates contact with combustion products well, as well as strong heating and sudden temperature changes, which allows it to be used for both internal and external walls of pipes;
• Aluminum. Has similar characteristics and scope of application to steel;
• Enameled connections. The most convenient and practical option, which, as a rule, does not require insulation, since it initially has it.

In general, in order to construct an open type chimney, you will need the following materials: bricks, concrete mortar and containers for mixing it, trowels of a suitable size, building level, Steel (from which the protective dome (umbrella) is assembled and the interior of the pipes is finished ).

The diameter of the chimney for a gas boiler plays a key role and affects the quality, efficiency, and safety of the heating unit.

If gas is chosen for heating the house, care should be taken to remove combustion products. This means that you need to select and correctly install a chimney for a gas boiler. Compliance with the rules and regulations in this matter absolutely cannot be neglected, since this can call into question not only the health, but also the life of the residents of the house.

One of the most dangerous products formed during almost all types of combustion is carbon monoxide. This is an insidious and very dangerous substance, the inhalation of which can lead to severe forms of poisoning.

When a gas boiler operates during fuel combustion, in addition to other combustion products, carbon monoxide is also formed.

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

The danger should not be underestimated. Carbon monoxide (also known as 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 have a very bad effect on other biochemical processes in the body. There have been cases when carbon monoxide poisoning was discovered too late, and the person simply could not be saved.

Image gallery

Correct operation of gas heating equipment largely depends on the system that removes combustion products. Before installing a chimney for a gas boiler in a private house, you need to have an idea of ​​the types of equipment, the principles of its operation and the regulatory documents according to which it is installed. Regardless of who will carry out the work, the choice of device and installation should be taken with full responsibility.

Installing a combustion product recovery system on a gas boiler contributes to the efficient functioning of the equipment and the entire heating system, safe and comfortable heating, as well as trouble-free operation of the boiler. Before buying a chimney for a gas boiler, it would be a good idea to get specialist advice about the existing options for chimneys and the feasibility of their use.

Types of smoke ducts for gas boilers:

• brick chimney - its construction is planned at the stage of building a house and a foundation is laid under it. A prerequisite is the smooth surface of the internal walls of the chimney. It should be noted that the structure must be resistant to acid, which is formed due to steam condensation. Otherwise, rapid destruction of the brick chimney pipe will occur. Used in combination with ceramic or steel liners. Brick chimneys for gas boilers are distinguished by their complex design, construction time and cost. In terms of technical indicators, they are in many ways inferior to the modern chimney systems that have emerged;

• stainless steel pipe design - this version of the chimney is highly resistant to chemical environments and mechanical damage. The system is made in the form of a sandwich structure: when a pipe with a smaller diameter is inserted into the outer pipe. Fire-resistant material - basalt wool - is placed in the free space between them. Manufacturers offer a wide selection of chimney models;
• coaxial chimney - the design is assembled according to the “pipe-in-pipe” principle: air for combustion is taken in through one pipe, and combustion products are discharged through the other. Such a system has high technical characteristics that help improve the safety of all gas equipment and increase its efficiency. And due to the fact that the combustion cycle occurs outdoors, a boiler with a coaxial chimney is environmentally friendly equipment;
• chimney made of ceramic pipes - consists of ceramic blocks with thermal insulation, installed in a concrete frame. Such a smoke exhaust system is resistant to temperature fluctuations, waterproof, fireproof and has high mechanical strength. The main requirement for installation is high-quality joining of ceramic modules.

Which chimney pipe is best to use - everyone decides based on their specific situation. The main thing is to highlight the strengths and weaknesses of any option. Regardless of what type of chimney you choose, its design and installation must comply with SNiP 2.04.05-91 “Heating, ventilation and air conditioning.” After studying these standards, you can learn how to properly install a chimney on a gas boiler.

Chimney for a gas boiler in a private house: basic requirements of SNiP 2.04.05-91

Measures for installing a chimney for a gas boiler, from the design stage to the actual installation of the system, must comply with the requirements of the current regulatory framework, since improper installation and operation of gas equipment calls into question the safety of people using gas installations.

Main elements of the chimney design:

• flue - a channel leaving the boiler into the chimney pipe, connected by an adapter;
• chimney pipes;
• revision - attached to the bottom of the smoke exhaust shaft and serves to clean the channel from combustion products and remove excess moisture;
• fastening elements (brackets, clamps) - used for fastening to the wall;
• other components for the system device.

As a rule, the location of a gas boiler in a private house is planned on the ground floor in a separate room (boiler room). All elements of the heating system must be connected to each other strictly tightly. The basic rules for installing chimneys for gas boilers, regulating the technological order, are presented in regulations SNiP 2.04.05-91 and contain the following requirements:

• proper draft - ensures complete removal of exhaust gases;

• resistance to high temperatures;
• tightness of connecting points - all components along the entire length of the chimney exhaust system must fit tightly to each other;
• the pipe where it passes through the ceiling must be solid, without joints;
• condensate collector - the design of this element must ensure the collection and removal of liquid;
• if the structure has turns, inspection hatches are installed in these places to diagnose the condition of the chimney, clean it and drain condensate;
• the length of the pipe branch to the side should not exceed 1 m;
• the permissible number of turns on chimney pipes is possible - no more than 3;
• the height of the chimney pipe must exceed the height of the roof (at the highest point) to ensure good draft and prevent reverse draft;
• the distance between the chimney pipes and the surface, which is made of non-combustible materials, can be at least 5 cm, and if the surface material is flammable - at least 25 cm.

Helpful advice! Complete sealing of the chimney sections will not allow hot combustion products to escape the system.

The procedure for installing a chimney for a gas boiler in a private house

Depending on the stage at which it is planned to install a chimney for a gas boiler, the exhaust system can be internal or external (remote). In cottages under construction, where the use of gas boilers is envisaged, internal chimneys are used, the placement of which is taken into account in the design. In old houses, when switching to heating using a gas boiler, the chimney is vented outside.

You can compare the strengths and weaknesses of external and external chimneys by reading the table:

Chimney type
Remote	Interior
Full thermal insulation of the chimney is required	Thermal insulation is only necessary in the area that faces the outside
Safe operation is guaranteed if the standards are followed	The possibility of combustion products entering the room cannot be ruled out; there is a high fire hazard
The chimney device is made of the same type of elements and is characterized by ease of execution	It is characterized by complex installation, since there is a need for a large number of components and components of the chimney
Availability of any kind of repair work and maintenance	Difficulty in maintaining and repairing the chimney

The installation of a chimney for an internal type gas boiler involves the construction of a foundation and a protective channel made of brick. Then safe operation will be ensured. Such systems are more efficient and the formation of condensate in them is minimal. In some cases, chimneys can be attached to the wall of the house behind which the boiler is installed.

The installation of an external chimney requires high-quality fastening and mandatory maximum insulation, since condensate in such structures is formed in larger quantities.

The main stages of installing a chimney for an internal gas boiler:

• marking places for making holes in the ceiling and roof of the house;
• arrangement of an opening for the chimney;
• connection of the boiler pipe with the gas duct;
• installation of revision, tee;

• extension of the chimney pipe;
• strengthening joints with clamps;
• fastening the structure with brackets;
• thermal insulation of the outer part.

Helpful advice! The location of the smoke exhaust system must be strictly vertical, without narrowing or widening the channel.

Chimneys for gas boilers made of stainless steel

Chimneys made of steel can have a single-walled or double-walled design. Single-layer exhaust pipes can be installed in heated rooms and used for lining brick chimneys. In three-layer systems, there is a heat-insulating layer between the two pipes, which makes it possible to use them for both internal and external installation.

Due to the fact that gas fuel contains sulfur impurities, when exhaust products are removed, its vapors have an aggressive effect, corroding the walls of the smoke exhaust channels. Therefore, in the production of stainless steel chimneys for gas boilers, heat-resistant and acid-resistant material AISI 316L is used. Its use greatly increases the service life of smoke exhaust systems.

One of the weak points of a stainless chimney pipe for a gas boiler is its not entirely aesthetic appearance. The benefits include:

• resistance to corrosion and aggressive chemical composition;
• light weight, no need for a foundation;
• non-flammability of the material - stainless steel does not melt even at a temperature of 500 ºС;
• modular design - factory production of a large number of tees, adapters and elbows allows you to integrate a chimney into any home;
• factory production of all elements of the steel chimney allows it to be assembled and removed at any convenient angle;
• absolutely smooth round inner surface - provides a minimum of obstacles to the exit of combustion products;
• possibility of installation in an already built house;
• Quite affordable price of a chimney for a gas boiler.

When installing an external chimney made of steel, there is a high probability of dew point formation: if the temperature outside is low, the exhaust vapors form condensation and a water plug is created. It clogs the channel, preventing products from escaping, and thereby blocks the combustion process. This can be avoided by placing the pipe in a brick-lined chimney duct. This technique will also solve the aesthetic side of the structure.

Another option to avoid the formation of a water plug is to use a sandwich structure of two pipes, one of which is protected by a layer of basalt wool. Such a remote chimney system no longer requires additional insulation. The diameter of the chimney for a gas boiler is selected so that it coincides with the cross-section of the equipment outlet.

Helpful advice! Stainless steel chimneys are easy to maintain, but it is necessary to have the system inspected by a specialist once every 3 years.

Rules for installing a chimney for a geyser

The key to safe operation of a gas water heater is a proper exhaust system. For the column, chimneys are used, which discharge combustion products into the smoke exhaust channel or directly into the atmosphere. The following types of pipes are used to remove exhaust gases:

• - easy to install, the flexibility of the material allows
  stretch it up to 2-3 m in length, and also lengthen it by connecting several sections of corrugation;
• aluminum pipe - easy to install, resistant to condensation, requires additional thermal insulation;
• coaxial chimneys - the price of such systems can be reduced due to the possibility of leading the pipe through the wall. This reduces material consumption and installation costs. The main advantage of such a chimney is that air from the room is not involved in the operation of all equipment.

Basic requirements for the installation of chimney pipes for geysers:

• operation of the devices is prohibited without a chimney securely fixed in it;
• the draft inside the chimney system must be constant;
• the pipe material must be non-flammable, resistant to corrosion, condensation and high temperatures;
• the outer section of the chimney must be vertical;
• the structure must be sealed to prevent carbon monoxide from entering the room;
• the exhaust pipe should be installed in an open place for quick troubleshooting if necessary;
• the chimney must be located at least 0.5 m above the roof level;
• It is strictly forbidden to use ventilation systems, the space between floors, or attics to remove combustion products.

How to check the draft in the chimney of a gas boiler

Draft is one of the main indicators of the proper functioning of the chimney. Its effectiveness depends on the following parameters:

• cross-section of the chimney pipe - heated gases are removed faster with a smaller cross-section, but if it is too small, there is a risk of combustion products entering the room. If the cross-section of the chimney is unreasonably large, a reverse draft effect may be created;

• accumulation of a large amount of soot on the walls of the barrel - due to this, the working cross-section is reduced, which leads to a decrease in the rate of carbon monoxide removal;
• a large number of turns in the system - any of the turns of the pipe inhibits the movement of exhaust gases;
• insufficient tightness of the chimney - the presence of small cracks and gaps allows cold air to penetrate into the system, which prevents the rapid removal of smoke;
• weather - high humidity and low atmospheric pressure can cause a decrease in traction.

You can check the state of traction using several methods. If diagnostics are carried out by professionals, they use an anemometer - a device for measuring the speed of gas movement. In everyday life they use the so-called folk methods:

• visual inspection - if there is smoke in the room, it means there is backdraft;
• using a thin sheet of paper - it is brought to the viewing window: the stronger the paper is attracted, the better the traction;
• candle flame - a lit candle is brought to the channel and the flame is blown out. The direction of smoke from an extinguished candle towards the chimney indicates good draft.

Important! The draft in gas boilers should be checked with the equipment turned off.

Depending on the reason why weak craving is observed, measures are taken to improve it. The channel is cleared of soot using a special device consisting of a brush, a sinker and a rope. The device is lowered into the canal and, with progressive movements, it is cleaned along its entire length. To achieve complete sealing of a brick chimney, it is necessary to eliminate all cracks formed as a result of the destruction of the masonry.

Coaxial chimney for a gas boiler: installation rules, advantages, installation

The main advantage of installing a coaxial chimney for a gas boiler is that such a chimney not only removes exhaust gases outside, but also provides the combustion chamber with air from the street. Thanks to this, the room does not require additional ventilation, and the air in the house remains capable of maintaining the health and performance of the people there. Equipment with such removal of combustion products is called a gas boiler without a chimney.

Design of a coaxial chimney

The design of a coaxial chimney is based on two pipes of different diameters, one of which is located inside the other. The inner pipe is designed to remove waste substances outside. Through the outer pipe, or rather, through the space between the inner and outer pipes, air is taken in from the outside, which is used for gas combustion. Thus, the chimney copes with several functions at once:

• increasing the degree of safety of the chimney - the incoming air from the street heats up, and the exiting combustion products cool down;
• increasing boiler performance - the efficiency of the equipment increases due to the fact that the air enters the combustion chamber already heated;
• maximum gas combustion - due to the fact that the boiler efficiency increases, complete combustion of fuel is achieved;
• environmental friendliness of the heating system - the entire operating cycle of gas equipment takes place outside, which ensures comfortable and safe heating.

To make a chimney, round pipes are used: the outer pipe with a diameter of 100 mm is made of steel 1-2 mm thick, the inner one is made of aluminum alloy. The diameter of the latter is 60 mm. Pipes with this ratio of diameters are used in coaxial chimneys for wall-mounted gas boilers and floor-standing devices with a closed combustion chamber. To avoid pipes coming into contact with each other, jumpers are installed along their entire length.

According to the installation method, coaxial type chimneys can be horizontal or vertical. The horizontal option is more popular due to its simple installation. In cases where it is technically impossible to install the system horizontally or the distance from the boiler to the outer wall exceeds 4 m, they resort to installing a vertical coaxial chimney. It is worth noting that its installation is more complicated.

Advantages of coaxial chimney systems

Coaxial chimneys are used for various gas equipment in which the combustion chamber has a closed structure. These are floor- and wall-mounted gas boilers, gas flow-through heaters (columns), convectors and other devices.

It is worth noting the main advantages of using coaxial chimneys over other types of gas exhaust systems:

• natural heat exchange - heating of the incoming air and cooling of the exhaust gases occurs due to the design of the pipe, which, in turn, prevents the wall from getting too hot;
• increasing the productivity of the gas equipment itself;
• compactness - the chimney is carefully installed and does not take up much space, which allows it to be used not only in private cottages, but also in high-rise apartments;

• operational safety - there is no lack of oxygen in the air of the room where the boiler is installed, since contact of the air from the room with the substances being eliminated is completely eliminated;
• ease of installation - allows you to reduce the cost of installing a coaxial chimney.

Helpful advice! If you purchased a wall-mounted gas boiler for autonomous heating of an apartment, using a coaxial chimney for it is the safest, since combustion products are not removed into the ventilation duct, but directly into the atmosphere.

Requirements for installing a coaxial chimney

As with any gas equipment, the installation of coaxial chimneys is subject to specific requirements SNiP 2.04.05–91, section 3 “Heating”; 2.04.08–87, as well as regulations regulated by the “Safety Rules in the Gas Industry”. They can be different depending on the installation method of the coaxial chimney: horizontal or vertical.

For any type of installation, there is a general requirement for the maximum length of a coaxial chimney for a gas boiler: it cannot exceed 4 m. When it is necessary to install a chimney exhaust system over a considerable distance, special coaxial models with dimensional standards are used.

When passing a vertical coaxial chimney for a gas boiler through the ceiling and roof, an adapter is used, the design of which is provided by the manufacturer specifically for this system. This also applies to coaxial chimney extensions when it is necessary to install a system of the required length. Tightness in places where pipes pass through the ceiling is ensured by a special head - a terminal. It also prevents precipitation from entering the system.

The horizontal method of installing a coaxial chimney is used, as a rule, for wall-mounted gas equipment. To avoid condensation, it is necessary to maintain a downward slope of the chimney from the boiler of 3 to 5%. There are standards for the location of smoke ducts for a chimney in the outer wall. So, if the hole is supposed to be in the wall next to the window, the distance to the window should not be less than 0.5 m, if above the window - not less than 0.25 m.

Many manufacturers of gas equipment also include a pipe for removing combustion products. If you bought a coaxial chimney for a gas boiler along with the equipment, you need to check that the kit includes a horizontal part of the pipe (usually about 1 m long), an outlet, a terminal (head), a set of sealing gaskets, and a membrane. If, when installing a pipe through a wall, it is necessary to bypass any protrusions or fittings, use elbows and bends.

Helpful advice! It is necessary to provide protection for all outputs and inputs on the coaxial chimney from foreign objects.

Coaxial chimney for a gas boiler in a private house: how to make it yourself

Before installing a coaxial chimney with your own hands, you must read the instructions for the design and operation of the purchased gas equipment. Due to the specific design of the coaxial pipe, the installation of a chimney for a wall-mounted gas boiler must be done with extreme caution. Avoid dents or other damage to the pipes that could lead to depressurization of the system.

To perform installation work, you will need the following system elements:

• pipe with flange;
• crimp clamps;
• coaxial elbow;
• adapter for connecting to the boiler;
• extension cord with sealing cuffs (if required);
• decorative overlays.

According to the requirements for chimney installation, a hole of the required diameter is made in the outer wall. If there is a window opening in the wall, it is necessary to place the hole at a distance no closer than 0.5 m from the window. When connecting a chimney to a gas boiler, first connect the adapter, and then all the links assembled into a single structure.

The pipe is led out through a hole in the wall, maintaining a slope from the boiler. If you need to connect the chimney to the wall, the structure is fixed with clamps. The gaps between the wall hole and the inserted pipe are filled with foam or sealed with mineral wool. After this, these places are covered with decorative rings.

Do-it-yourself brick chimney installation

The brick chimney design is an exclusively vertical channel with a square or rectangular cross-section. To lay a brick chimney, solid ceramic bricks are used, which are laid on mortar. The outer section of the channel is laid out with ordinary brick, corresponding in style to house construction, which can be seen in numerous photos of brick chimneys. If the house is lined with stone or plastered, you can decorate the chimney in the same way.

Brick chimneys for gas boilers: installation requirements

Before laying a brick chimney for a boiler, it is necessary to build a foundation, the height of which must be at least 0.3 m. The dimensions of the base around the perimeter must protrude beyond the contour of the channel itself by at least 0.15 m. If the chimney is located in part of the external wall, its foundation should be level with its base. Laying a brick chimney with your own hands (video instructions confirm this) begins at the stage of building the walls of the house.

Requirements for brick chimneys:

• the smoke channel must be vertical, without ledges, narrowed or widened areas;
• the thickness of the brick pipe for the chimney is taken taking into account the exclusion of freezing;
• the minimum permissible cross-section of smoke exhaust ducts is 14 x 14 cm, which corresponds to the size of half a brick, taking into account the seam;
• the size of a brick chimney, the height of which is less than 5 m, should be increased to a channel cross-section of 14 x 20 cm;
• the chimney is constructed in the walls between heated rooms, which will prevent it from cooling and reducing draft;
• tightness - the brick chimney is laid with ligation so that the vertical seam of the previous row overlaps with the brick of the next one;
• the inner surface of the channel must be smooth;

Helpful advice! To achieve a flat and smooth inner surface of the channel, use special templates when building a brick chimney with your own hands.

• the distance between adjacent smoke exhaust ducts should not be less than 5 average outer diameters of the pipe;

• if ventilation ducts are located near the chimney, their height should be equal to the height of the chimneys.

To reduce construction costs, you should place as many channels as possible in a common chimney. In this case, adjacent chimney and ventilation ducts will heat each other, which will generally improve the functioning of the chimney.

Preparation of mortar for laying a brick chimney

The composition of the mortar for laying a brick chimney is selected taking into account which section of the pipe is being laid: external or internal. To construct the external channel, the same mortar is used as for laying load-bearing walls of house construction. It is prepared from cement, sand, water and can harden in air and water. The mixture is prepared in such a volume that it can be used within an hour, as it sets quickly.

To ensure that the mixture does not deteriorate under the influence of an aggressive environment, it is recommended to add special additives to it that increase its plasticity, strength and acid resistance. Thanks to these additives, you can improve the quality of the masonry itself, increase the speed of construction and the durability of the work performed.

The preparation of a solution for a brick chimney running inside a house is based on the use of fireclay and fireclay in its composition in a 1: 1 ratio. Such mixtures cope well with high temperatures, they are durable and do not emit harmful substances. To give the clay mixture strength, you can add table salt to its composition (about 120-150 g per bucket).

Helpful advice! The strength of the chimney mortar can be enhanced by adding Portland cement in a proportion of 1 kg per bucket.

When laying a brick chimney with your own hands, you can purchase ready-made mixtures that are heat-resistant and acid-resistant. Preparing the solution yourself can reduce the cost of building a chimney.

It is quite possible to build a brick chimney with your own hands - the video below will help you familiarize yourself in detail with the stages of constructing the structure, taking into account all the basic requirements.

The feasibility of using a brick chimney for a gas boiler

Taking into account the advantages and disadvantages of brick chimneys, it is possible to draw conclusions regarding their use in combination with gas boilers. Their advantages include:

• the likelihood of using an existing chimney duct, which reduces chimney costs;
• possibility of operation in conjunction with gas equipment with an open combustion chamber;
• reasonable cost of materials for construction and finishing of the structure.

The durability of brick channels is observed only when they are used for fireplaces or stoves. If they are used for gas boilers, due to the low temperature of the combustion products, condensation will form on the channel walls, and harsh operating conditions in an aggressive environment will lead to the gradual destruction of the brickwork and deterioration in performance.

In addition, the requirements for such chimneys are more stringent:

• impeccable masonry - if the skills are not enough, it will be necessary to invite a qualified mason to work, which will cost a lot of money. Prices for work: rough brick masonry from 6,000 rubles per 1 m³, facing masonry - 2,500 rubles. for 1 m²;

• inability to perform a complex channel configuration (if you need to bypass, for example, a beam in a ceiling);
• the use of the old channel should be carried out using sleeves;
• the need for thermal insulation.

The disadvantages of such a system include a decrease in traction while the brick is warming up. Thus, the correct chimney for a gas boiler will be a brick channel together with a steel or ceramic liner. The photo of brick chimneys shows that liners are installed during the process of laying the channel. In this case, it is necessary to leave a gap between the liner pipe and the brick surface. This is necessary so that the pipe can move inside the channel.

Chimneys for gas boilers: prices for different types of pipes

When planning your budget when purchasing chimney pipes, you should take into account the length and diameter of the channel, the presence and number of turns, as well as the material from which the pipes are made. There are no fundamental differences in the design and cost of chimneys for floor-standing gas boilers and wall-mounted appliances. A stainless steel chimney will cost more than a brick chimney, but a steel pipe is easier to install, which makes its installation costs quite affordable.

You can buy a chimney for a gas boiler at specialized sales points and in online stores that sell these products. A large assortment of fittings, shaped parts, tees, adapters, plugs and other necessary structural parts is also offered for sale. Given the convenient sorting of products by category and model, you can quickly find and order the product you need.

The cost of 1 m of a single-circuit stainless steel pipe with diameters of 100, 110, 115, 120 mm is 650 rubles, the same pipe with a diameter of 140-150 mm will cost 750 rubles. The price of an elbow with a rotation angle of 90° made of stainless steel for a pipe with a diameter of 110-120 mm is 550 rubles. with a metal thickness of 0.6 mm. You can purchase 1 m of stainless steel sandwich pipe with a diameter of 140-230 mm for 1,900 rubles.

Helpful advice! You can save on purchasing high-quality and durable chimney pipes if you place an order during the discount period.

The price of a coaxial chimney for a gas boiler with a diameter of 60-100 mm and a length of 1 m, sold in a horizontal set, is 3,500 rubles. The purchase of a coaxial chimney from Baxi, a global manufacturer of modern heating systems, will cost 4,200 rubles. A complete chimney kit for a wall-mounted gas boiler includes a 75 cm long pipe with a diameter of 60-100 mm, a 90° bend and a tip. All products are guaranteed.

Proper installation of any household appliance is the key to its safe and long-term operation. Especially when it comes to gas equipment. Installation of a combustion product removal system for gas boilers requires preliminary engineering calculations and qualified implementation.

To remove combustion products generated during the combustion of natural gas, chimneys of various designs are used. Previously, chimneys were built only from asbestos-cement pipes and bricks. Nowadays, a smoke exhaust pipe can be assembled from durable and lightweight materials that are much less expensive.

Requirements for chimneys for gas boilers

Design, assembly, installation and other activities aimed at installing a smoke duct are regulated by regulatory documents that clearly and clearly state the basic requirements for these structures.

Regulatory documents regulating the installation of chimneys for gas boilers include SNiP 2.04.05–91 “Heating, ventilation and air conditioning”, as well as DBN V.2.5–20–2001 “Internal gas supply arrangement”.

For floor-mounted and wall-mounted gas boilers, a steel chimney is most often installed

Based on these documents, the following requirements are imposed on smoke exhaust structures that will be used in conjunction with heating boilers:

The above requirements are general and must be met in all cases without exception. When installing a chimney, you should remember that even small deviations from the values ​​​​required by regulatory documents can cause a decrease in the service life of the chimney, and in some cases lead to more serious consequences.

Boiler structures and chimney outlet

Structurally, a gas boiler is a device consisting of a gas burner, to which gas is supplied through nozzles, and a heat exchanger, which is heated by the energy obtained during gas combustion. The gas burner is located in the combustion chamber. Heat movement occurs using a circular pump.

In addition, modern types of gas boilers are equipped with various self-diagnosis and automation modules, allowing the equipment to be used in autonomous mode. When choosing a chimney, pay attention to the type of boiler combustion chamber. The method of intake of air necessary for gas combustion, and as a result, the optimal type of chimney, will depend on its design.

Different types of chimneys are suitable for different types of combustion chambers

The combustion chamber of gas boilers is of two types:

• open - provides natural traction. The air is taken from the room in which the heating equipment is installed. The removal of combustion products is carried out through natural draft using a chimney with an exit through the roof;
• closed - provides forced traction. Air intake for fuel combustion comes from the street. In rare cases, air can be taken from a special room equipped with forced ventilation. To simultaneously remove flue gases and intake fresh air, a coaxial type chimney is used, which is vented outside through the nearest load-bearing wall.

Knowing the type of combustion chamber, you can easily select or manufacture a chimney suitable for the design. In the first case, when the boiler is equipped with an open combustion chamber, a conventional thin-walled or insulated chimney is used.

For boilers with a closed combustion chamber, a coaxial chimney is used, which is a structure consisting of pipes of different diameters. A pipe with a smaller cross-section is fixed inside a pipe of a larger diameter using special racks. Carbon dioxide and other combustion products are removed through the internal channel, and through the gap between the outer and inner pipes, fresh air enters the closed combustion chamber.

Methods for installing chimneys

According to the method of installation, chimneys are divided into:

• internal - chimneys made of metal, brick or ceramics. They are available in both single-wall and insulated double-wall constructions. Positioned vertically upward. There may be several elbows with a 30° offset;
• external - coaxial or sandwich chimneys. They are also located vertically upward, but the chimney is led out horizontally through the load-bearing wall. After the pipe has been removed, a 90° swivel elbow and support brackets are installed to allow installation in the desired direction.

The chimney can be vented outside through a wall in the immediate vicinity of the boiler or in the traditional way through the roof

When choosing a chimney installation method, you should take into account the size of the building in which the equipment is located. For small buildings, it is more advisable to use external chimneys, as they allow the chimney to be taken outside the premises.

In other cases, you should build on your personal capabilities. If space allows and it is possible to provide high-quality insulation where the pipe passes through the ceilings, then an internal chimney will be the best solution. Especially if the structure is lined with brick or protected by a ceramic box.

Do-it-yourself chimneys for gas boilers

As with other heating equipment, a chimney for a gas boiler can be purchased in specialized stores. This will be a standard modular product, which is selected taking into account the type of boiler and its power.

What to make a chimney for a gas boiler from

A chimney for a gas boiler can be made from various materials. The main thing is that the material is non-flammable, resistant to chemically aggressive environments and does not allow gases to pass through the smoke duct.

For the manufacture of steel chimney parts, steel with the addition of molybdenum, titanium and nickel is used

Taking into account regulatory requirements, the following materials are used for the manufacture of the chimney:

• brick is a traditional material for the manufacture of chimneys for solid fuel stoves. For laying the chimney, class A or B stove fire-resistant bricks are used. When using gas equipment, a combined approach is often used, when a steel or asbestos-cement pipe is used as an internal channel;
• steel - used to create chimneys of any configuration. The quality and heat resistance of a material is determined by its alloy, which is indicated by a special marking. Thus, for the manufacture of chimneys, products made of AISI 316i, AISI 321 or AISI 310S steel are better suited;
• ceramics - a fired mixture of clay and sand, from which combined chimneys are made. The internal channel is made of a ceramic pipe of a certain cross-section. A box made of expanded clay concrete shell or brick is used as a protective casing.

If we carry out a detailed comparison, the best material in terms of price and quality ratio is galvanized steel AISI 321 and AISI 310S. Chimneys made of such steel are designed for flue gas temperatures up to 800 and 1000 o C, respectively.

Ceramic chimneys have high performance characteristics, but their cost is noticeably higher than their steel counterparts

The average service life of steel chimneys is 13–17 years, but due to the high standardization of parts, there is no need to completely change the design. During repairs, only part of the burnt-out modules are replaced.

Ceramic chimneys have high performance characteristics and a service life of more than 50 years, but their cost is noticeably higher than their steel counterparts. Therefore, this type of chimney is recommended to be used only if there is a sufficient amount of funds and you want to build a structure for a long time. The use of brick chimneys in conjunction with gas equipment is unjustified both in terms of labor costs and the final cost of the structure.

How to calculate chimney parameters for a gas boiler

In order to correctly select or manufacture a chimney, it is necessary to calculate the cross-section of the chimney, as well as its height relative to the level of the ridge. The total height of the chimney is selected in accordance with the regulatory rules specified in SNiP 2.04.05–91.

Table: dependence of the chimney cross-section on the power of the gas boiler

To calculate the pipe cross-section, the following formula is used - F = (K ∙ Q) / (4.19 ∙ √ˉ N), where:

• K is a constant value, the value of which varies from 0.02 to 0.03;
• Q is the maximum performance of gas equipment specified in the specification;
• H is the estimated height of the chimney according to SNiP.

For gas boilers, the minimum height of the chimney must be at least 5 m. The height relative to the ridge is selected from the rules described at the beginning of the article. Let us remind you that the minimum height relative to the ridge must be at least 0.5 m.

After the pipe area has been calculated, it is necessary to compare the obtained value with the data shown in the table. If necessary, the calculated diameter of the smoke channel is rounded to a larger value.

DIY chimney installation

To assemble the chimney, single-circuit steel pipes or special sandwich pipes of the required diameter are used. If the first option is chosen, then after assembling the chimney it is recommended to insulate it. In the second case, there is no need to insulate the chimney.

When using a sandwich chimney, additional insulation of the chimney is not required

As an example, we will give the technology for installing a steel chimney for a gas boiler. To assemble the chimney, you will need straight steel pipes 50 or 100 cm long, 30° chimney outlets, a passage box for walls and ceilings, a deflector, crimp clamps and heat-resistant sealant.

If the diameter of the outlet pipe does not match the diameter of the chimney, then an appropriate adapter is used. It is better to use basalt wool as an insulating material.

Installation of a chimney for a gas boiler is carried out in the following sequence:

1. A single-wall or insulated pipe is connected to the outlet pipe of the gas boiler. To do this, the pipe is coated with a heat-resistant sealant, after which an adapter is put on it, which is tightened with a crimp clamp.
2. A similar approach is used to connect the adapter to the pipe. First, the mounting end of the adapter is treated with sealant. Next, a straight pipe is placed on it to the required depth. After which the connection is tightened with a clamp.

   
   Before assembling the chimney, it is recommended to check its completeness for the presence of all modules and fasteners

3. To bring the chimney through the ceiling, you will need to cut a square hole in it. The size of the hole is selected so that there is a distance of at least 20 cm from the chimney to the ceiling.
4. A steel box is mounted into a hole cut into the ceiling. For fastening, steel screws 30–50 mm long are used. Then a pipe is passed through the box, which is mounted on a module connected to the pipe. The space between the pipe and the box is filled with mineralized insulation. The top of the box is closed with a steel plate.

   
   The outlet of the chimney through the ceiling must be insulated with a steel box

5. If, after introducing the pipe into the inter-attic space, its displacement is required, then a 30° elbow is installed according to the scheme described above. In other cases, a straight section of pipe is installed.
6. To remove the chimney through the roof, similar actions are performed. First, a square hole of the required size is cut out. Next, a mounting plate with a hole for the pipe is installed. Then a straight section of the chimney is installed. Finally, a conical additional element made of steel or non-flammable plastic is put on the chimney.

   
   A deflector must be installed at the chimney outlet

7. At the final stage, the remaining section of the chimney is installed. A head and a deflector are installed at the end of the pipe. After assembly, the functionality of the assembled structure is checked. To do this, it is enough for the equipment to operate at 50–60% of maximum power for one hour.

When installing an external chimney, a 90° rotary elbow is used. The elbow is connected directly to the adapter, which is also mounted on the gas boiler pipe.

To remove the chimney, you will need to cut a hole in the load-bearing wall. The size of the hole is selected in the same way as in the case of the ceiling and roof. Next, a steel box is mounted in the wall through which the pipe is passed. Basalt or mineral wool is used to fill the box.

To re-rotate the pipe, another 90° elbow is installed. A special support with a bracket is used as a supporting structure, which is installed under the rotating elbow. The installation step of the hanging brackets is 1–1.5 m. Further steps are similar - you need to assemble a chimney from straight products that are connected using clamps and sealant.

Do-it-yourself coaxial chimney for a gas boiler

Before installing a coaxial chimney, you must check the completeness of the purchased product. If any of the elements is missing, then you should replace the missing set with a complete one, which should include:

• pipe with flange;
• coaxial elbow 90 o;
• connection adapter;
• wall trims;
• O-rings;
• connecting clamps;
• decorative rosette;
• mounting screws.

To assemble a coaxial chimney, you must have a complete set of pipes and connecting elements

The installation process of a coaxial chimney consists of the following steps:

Depending on the manufacturer, the composition of the chimney installation kit may differ slightly, but the main elements in the form of an elbow, pipe, clamps and linings must be included in the kit. Before installing a coaxial chimney, it is strongly recommended to study the instructions.

Video: chimney for a gas boiler made of sandwich pipes

How to reduce the temperature of flue gases in a chimney

When natural gas is burned, carbon dioxide, steam, sulfurous salt-forming oxides, etc. are formed. The optimal temperature of the flue gases at the outlet of the chimney should be 100–110 o C.

If the temperature of the flue gases is below the dew point, that is, the condensation temperature of the air, then the water vapor contained in the combustion products will settle on the walls of the chimney. If this happens constantly, the chimney can quickly collapse.

If the temperature of the flue gases is too low, condensation will form at the outlet of the chimney, and the outer part of the pipe will begin to freeze

In addition, the presence of constant condensation in the smoke channel leads to a weakening of natural draft. Therefore, it is so important to monitor the temperature of the flue gases, which directly depends on the cross-section of the chimney.

From the above we can conclude that with correct calculation, the temperature of the flue gases will be in the region of optimal values. If the temperature is too high and needs to be reduced, this directly indicates that the cross-section of the chimney does not correspond to the power of the gas boiler. To reduce the temperature of the exhaust gases, it is recommended to reassemble the smoke exhaust system taking into account the standard values.

Video: condensation in the chimney

How to check and adjust the draft in the chimney of a gas boiler

Draft is a decrease in pressure in the place where fuel combustion occurs. The pressure decrease occurs due to the removal of combustion products through the smoke channel. Speaking within the framework of this article, draft forces fresh air into the combustion chamber, where there is a reduced pressure that occurs due to the fact that gas combustion products are discharged outside.

The presence of draft indicates that the chimney is designed and installed correctly, and the equipment is working properly. The lack of draft may be a direct or indirect confirmation of the need for preventive maintenance or repair of equipment and the chimney system.

The speed of air flow in the chimney can be measured with a special device - an anemometer

The following methods are used to check the draft level:

• visual inspection - there should be no smoke in the room where the heating equipment is located;
• using improvised means, for example, a sheet of paper. It is brought to the inspection hole. If there is traction, then the sheet will deviate towards the hole;
• measurement with a special device - an anemometer. It is used to control air speed.

To control traction, it is better to use the latter method, since only it will show the exact value. When measuring natural draft, the flue gas velocity should be in the range of 6–10 m/s. The value is taken from SP 41–104–2000 “Design of autonomous heat supply sources.”

If it is necessary to reduce the draft level, then this will require reassembling the chimney based on a chimney of a larger cross-section. To increase traction, it is recommended to check the quality of the installation joints and mechanically clean the smoke channel using a steel cable with a brush attachment.

If this does not help, then the only way out is to replace the chimney with a preliminary calculation of the chimney cross-section. In this case, it is desirable to reduce the number of rotating elements to a minimum or remove them altogether.

Why does the boiler blow out and how to fix it

The main reason why the burner in a boiler blows out is the backdraft effect that occurs due to problems with the chimney.

Before starting any measures, you should check the height of the chimney above the ridge level and the presence of an installed deflector, which reduces the penetration of wind flows into the chimney. If the pipe installation is not carried out according to the rules, then after the steps described below, you will need to extend the pipe and install a deflector.

Sometimes, in order to increase draft, you need to clear the chimney of soot

In order to solve the problem with the boiler blowing out, you will need to do the following:

1. First of all, you need to check the draft level in the pipe. It is better to use an anemometer. If you cannot find it, then with the boiler running you need to lean the paper against the outlet of the chimney. If the sheet is attracted to the chimney, then there should be no problems with draft.
2. If you find that the blowing occurs due to a loss of natural draft, you will need to check the chimney joints. A thermal imager is used for this. If the pipe allows air to pass through, the device will show a strong temperature difference between the main pipe and the junction of the two modules.
3. If the chimney is assembled correctly, then it is necessary to clean the smoke channel using a cable with a nozzle. The diameter of the nozzle is selected to match the cross-section of the chimney pipe. To remove soot, tar and other combustion products, an inspection hole is used at the bottom of the chimney.
4. After completing these simple steps, you will need to check the traction level again. If natural draft has not improved, then it is necessary to carry out work to correct the height of the chimney and install a deflector. During installation, heat-resistant sealant and crimp clamps are used.

In cases where the work described above does not produce results, you should contact the gas service to check the gas equipment. Perhaps the problems with blowing are associated with hypersensitive automation.

Video: how to check draft in a gas boiler

Compliance with regulatory requirements is a guarantee that no emergency situations will arise during the operation of the chimney. This is especially true for vertical chimneys, when correcting errors made during their installation will require spending a lot of time.

Installation of boiler equipment and its efficient operation is impossible without a chimney.

The correct choice of materials and compliance with standards when connecting is the key to your safety.

Gas services strictly control the commissioning process and may fine violators or forcibly disconnect the user from the gas supply.

Basic requirements for materials:

• fire resistance;
• anti-corrosion properties;
• resistance to the effects of acid formed as a result of the interaction of condensate with combustion products;
• long period of use.

Brick chimney. It has low draft and is prone to rapid destruction due to the formation of abundant condensation on the surface, which turns into an ice crust during the cold season. Ideal only for fireplaces or as a kind of cover for a stainless steel chimney.

Stainless steel. It has a lot of advantages, which makes it one of the first in popularity among its peers. It has good traction, fire resistance and anti-corrosion, and a long service life (especially dual-circuit models). The modular assembly method allows you to create steel chimneys of different configurations and is accessible even to a non-professional. Compatible with high-power boilers. Will serve you for 15 years.

Chimneys made of galvanized steel behave much worse during use. Galvanization is susceptible to rust.

Service life – maximum 5 years.

Ceramic chimney. Externally, it is as massive as brick. The installation option is strictly vertical only. Austrian manufacturers have developed models of ceramic chimneys with an external contour not only made of ceramics, but also of metal. They are much lighter, but when installing them you need to calculate the loads on the foundation and walls. Warranty up to 30 years.

Asbestos cement pipes. Short service life (5 years), difficult to install, not environmentally friendly. Even the low price of the material cannot serve as a compelling reason to choose such a chimney. Overheating can simply rupture the pipe. Suitable for occasional use in the countryside.

Coaxial- made of aluminum in the form of two sandwich pipes with different diameters, located one inside the other. The external one is intended for supplying air, and the internal one is for removing combustion products. The structure is prefabricated. The location is most often horizontal.

Advantages of a coaxial chimney:

• Safety
• Increased efficiency of the heating system
• Environmental friendliness

Chimney elements

Regardless of the material, the design includes the following elements:

1. Tee with revision— a fitting for condensate is installed at the bottom of the tee
2. Adapter for connecting the gas boiler pipe and the chimney
3. Fastenings- brackets and clamps
4. Cone shaped tip
5. Bends— installed no further than 2 meters from the beginning, otherwise the boiler draft is reduced;
6. Feedthrough
7. Telescopic pipes

Size Requirements

• Smoke channel should not contain ledges and be positioned strictly vertically. With a narrowed cross-section, a significant reduction in draft occurs, and when using pipes with a large diameter, it is possible to blow into the boiler chamber, with its subsequent attenuation.
• Sectional area of ​​the chimney pipe should not be smaller than the area of ​​the pipe through which the chimney is connected to the boiler.

How to calculate the chimney diameter

Key parameters- cross-sectional area (outlet F cm2).

The calculation is made using the formula F = (K ∙ Q) / (4.19 ∙ √ˉ N), Where:

K- coefficient calculated empirically (0.02-0.03);

Q- performance indicator of the gas appliance (indicated in the technical characteristics of the boiler);

N- chimney height.

The resulting number is adjusted by building codes and regulations.

For example, if brick is used, then the cross-section is 0.5 x 0.5 material.
For asbestos cement, the diameter is at least 10 cm.

Diameter of round chimney with a boiler power of 24 kW it should be 120 mm, 30 kW - 130 mm, 45 kW - 170 mm, 55 kW - 190 mm, 80 kW - 220 mm and 100 kW - 230 mm.
The minimum cross-section of rectangular channels depends on the thermal power of the boiler:

• Up to 3.5 kW - 14 by 14 cm.
• 3.5 to 5.2 kW - 14 by 20 cm.
• From 5.2 to 7.3 kW - 14 by 27 cm.

Design rules for boilers with natural removal of combustion products

• • The chimney pipe must be located above the ridge of the roof, is at least 0.5 meters higher than it, provided that its axis is close to the ridge or parapet (less than 1 m and no more than 1.5 m).
  • If the pipe is located further from the ridge (from 1.5 m to 3 m), then its height should be level with the ridge.
  • When the chimney is located at a distance of more than 3 m, its height must not exceed the boundary of a line laid down from the ridge at an angle of 10° to the horizontal.
  • If you have a flat roof, the height of your chimney should also have a minimum limit of 0.5 m, and in the case of a combined roof – 2 m.

A smoke removal pipe outside the building cannot be erected without insulation: the resulting condensate will destroy the chimney.

• The system for ejecting combustion products must be fixed to the wall at intervals of no more than 2.5 meters, in areas with a slope - every 1.5 meters.
• Clamp must be used on any connecting section of an insulated chimney.
• Chimney elbow must have a slope angle of at least 15 ° and no more than 90 ° (no more than three rotary bends in the system are allowed). The vertical section following the turn must be clearly secured with fastenings. It is prohibited to load inclined sections of the pipe or its bends.

• It is necessary to equip the chimney with a condensate drain, which must be available for service.
• The chimney must be insulated from flammable materials using brickwork or asbestos board. The distance from the connecting pipe to flammable surfaces must be at least 25 cm, and if a protective layer is applied - from 10 to 5 cm.
• Stable traction can be ensured, if you build a pipe above the wind pressure zone.

• Smoke exhaust systems built inside the building do not need to be additionally insulated, but it is necessary to take care of the tightness and ventilation system. Toxic smoke can easily seep even through the brickwork of the protective casing.
• Areas located outside the structure are insulated. In the absence of thermal insulation, the gases quickly cool, the draft decreases, and the boiler power drops. Condensation forms on the walls.

Requirements for installation of coaxial chimneys

When installing the smoke duct of such boilers, it is necessary to keep in mind that:

• When the length of the coaxial pipe is no more than 1 meter, it is necessary to install a tapering diaphragm on the air duct. The power of the fan in the chimney is designed for a certain pipe length and, if it is less, there will be a loss of draft with all the ensuing consequences.
• The pipe is located in a horizontal plane, but should still have a slope of 1 cm for each meter of total length and no more than two knees.
• Pipe head can protrude outward no more than the length of its tip - to protect against freezing, and not lower than 2 meters from the surface of the earth.

What do SNiPs say?

The installation of smoke ducts for gas boilers is regulated SNiP 2.04.05-91, and DBN V.2.5-20-2001

If you comply with all requirements during installation work, you can be sure that the gas service specialists will not have any questions for you. On cold winter evenings, your family will be warm and safe.

To learn how to choose and install a chimney correctly, watch the video: