To equip a private house with a chimney for a gas boiler, you must adhere to certain rules. The part of the pipe rising above the roof is just a small part of a complex structure. The pipe removes smoke and gas from the house. Having a private house, you must understand how the chimney works in order to imagine the operation of the heating system and understand how to operate it correctly. First of all, when planning the installation of a gas heating boiler, you should consider various chimney options and learn about their advantages and disadvantages.
Which chimney to choose
When equipping a private house with a chimney for a gas boiler, it is worth familiarizing yourself with their varieties. The previously popular brick options are no longer used so often. These are outdated designs, quite complex in design, taking up a lot of space. In addition, their construction is quite long-term and expensive, and the characteristics of bricks are inferior to modern materials. Therefore, most owners who have a private house that is heated by a gas boiler abandon brick options in favor of new designs.
Using stainless pipe
Stainless steel can be successfully used when installing a chimney in a private home. The undoubted advantages of steel are high strength and resistance to aggressive substances. Steel structures are a sandwich system of two pipes of different diameters. The gap between them is filled with heat-resistant insulation. They look modern and are highly reliable. Currently, options of this type are among the most popular.
Coaxial chimney
A good solution for a boiler would be a coaxial chimney. Its biggest advantage is that condensation is not able to form on its inner surface. But for systems operating on gas fuel this is one of the main advantages. In addition, this model is very attractive in appearance and has all the necessary characteristics.
Using a ceramic chimney
The ceramic structure can also be used when equipping a private house with a chimney. This solution is very reliable, fireproof and affordable. The luxury construction segment today uses just such options. In addition to all the above advantages, they are easy to install.
Requirements for chimneys of gas boilers
All existing requirements governing the rules and features of installing a chimney for a gas boiler are prescribed in SNiP 2.04.05-91. They must be strictly observed, otherwise the installation will be carried out incorrectly, and it will not be possible to connect the structure without violations. And this will naturally affect the safety of operation. One of the most important parameters necessary for the proper operation of a gas boiler will be to ensure good draft. This will help to efficiently use thermal energy. In addition, there are several more mandatory rules:
- The chimney must be equipped with a condensate collector to prevent excess moisture from accumulating on the walls of the structure.
- The head does not need to be equipped with fungi and deflectors, as they make it difficult to remove soot. These elements can cause carbon monoxide to enter your home.
- When equipping a private house with a chimney, special attention must be paid to the joints of the structure, all elements must fit tightly to each other, it is necessary to achieve absolute tightness.
- If it is necessary to create sloping sections, their angle cannot exceed 30 degrees.
- Any branches to the sides should be no more than 1 meter.
- During installation, cross sections are excluded, and elbows are placed only in the necessary places and in an amount of no more than three. When installing elbows, it is necessary to equip the system with inspection hatches for easy cleaning of the structure.
- If it is necessary to extend the pipes, the links should be connected to each other with an overlap, which will be half the diameter of the pipe.
- The bottom of the pipe is equipped with a drip and inspection.
- A private house contains partitions and ceilings, and pipe joints should not coincide with them.
- Horizontally located parts of the pipe, if a private house is still under construction, cannot be longer than 3 meters. For finished buildings this value is no more than 6 meters.
- If there are flammable materials in the building structure, the chimney of the gas boiler must be located at least 25 cm from them.
- If a pipe passes through flammable structures from which a private house is built, it must be well insulated. Use basalt wool and fire-resistant mastic.
Indoor or outdoor installation
Chimneys can be internal or external. The internal design is different in that it does not require thermal insulation. It passes through all the rooms and only the outer part is insulated. Installation of an internal chimney involves composing several parts of different diameters, which will lead to certain difficulties in sealing. The disadvantage of this solution is that there is a high probability of carbon monoxide entering the house. In addition, the internal chimney is quite difficult to repair.
The external option is more fireproof, but requires good thermal insulation. All its parts fit well together, which makes installation of the structure easier. By equipping a private house with an external chimney, you can be sure that subsequent cleaning and repairs will not cause any particular difficulties.
Internal chimney device
Before you begin installing the chimney, you need to mark the roof and ceilings of a private house, and mark the places where you need to cut holes. You need to measure everything very carefully, carefully thinking through the future design. Only after analyzing everything can you cut out the openings. The pipe leaving the gas boiler is connected to an adapter. Next, the tee and revision are installed, the main bracket is fixed and the structure is equipped with all the necessary fittings. If there is a need to extend the pipe, you can use elbows.
Important ! If installation is carried out through the ceiling, you need to use a special pipe. A galvanized sheet of iron is placed on the chimney pipe, which is fixed to the ceiling with clamps or wire.
Features of connecting a gas boiler to a chimney
A chimney for a gas boiler cannot be connected to several heating devices simultaneously by combining pipes. Since in this case a private house can be filled with combustion products. Materials of different compositions: brick, galvanized iron, asbestos or aluminum are not combined together. The optimal height for installing a chimney is 5 meters or more. If the house has a flat roof, then the pipe should rise 1.5 meters above it.
If a private house is equipped with a pipe whose height is more than two meters, it must be additionally secured with construction braces.
Exiting the chimney to the outside
The diameter of the chimney for a gas boiler must correspond to the diameter of the heater outlet. To bring it outside, you need to first measure all the dimensions and mark the area for work. After the holes are made, the passage element is connected to the gas boiler pipe, and the pipe is led out to the street. The holes formed as a result of the pipe exit must be well insulated.
Since your private house is equipped with a gas boiler, another tee with an inspection is installed on the chimney and a plug is put on. The pipe should be extended with several links, which are attached to the wall with brackets, the distance between which should be no more than 2 meters. Use clamps for reinforcement.
When the required pipe height is reached, a cone-shaped tip is installed to protect from wind and precipitation. Next, you should arrange thermal insulation. It is carried out if your private house is equipped with a chimney not made of sandwich material. A wall-mounted gas boiler must, first of all, be safe and efficient, and then you should think about aesthetics.
Important ! If you decide to install a chimney and connect a gas boiler yourself, carefully study the technology. Otherwise, if you are not confident in yourself, it is better to trust professionals who can guarantee safety.
Requirements for installing a chimney in a private house
It is necessary to equip a private house with a chimney in compliance with all rules. Gas removal and air supply to the boiler are carried out using special equipment. It resembles a mine with a pipe inside. The chimney is mounted vertically. There should be no expansions or contractions inside the channel, or any interference with air movement.
For installation, only non-flammable, non-melting, non-toxic, safe materials are used. The design eliminates the presence of cracks and other damage so that combustion products do not penetrate into a private home. All joints are sealed with special heat-resistant sealants. The height and diameter of the pipe must correspond to the parameters of the gas boiler. Otherwise, the traction will be insufficient.
How to install a chimney for a gas boiler in a private house? Is it possible to retrofit an old chimney? What is the difference between a chimney for a gas boiler?
What technical requirements are there? You can find answers to these and other questions in this article.
What types of chimneys are there?
Before installing a gas boiler, you need to take care of the chimney installation. To do this, you can hire workers, or you can make a chimney with your own hands.
It's not difficult, although there are still certain requirements. First, you should familiarize yourself with the different types of chimneys.
Chimneys can be made of:
- bricks;
- ceramic pipes;
- of stainless steel;
- coaxial chimney.
Brick chimney
A brick chimney is undoubtedly the cheapest option, but perhaps the most difficult to make with your own hands.
The fact is that a brick pipe has quite a decent weight. Therefore, its construction requires laying a foundation. But ventilation ducts can be installed in the brick pipe itself.
The pipe laying should be done from solid ceramic bricks. To make the upper part of the pipe protruding above the roof surface, it is permissible to use facing bricks.
The requirements for brickwork are such that the thickness of the chimney wall can be half a brick.
But to ensure the strength and reliability of the pipe, it is recommended to lay it in at least one brick.
For a gas boiler, a smoke exhaust duct with a cross-section of half a brick will be sufficient. If desired, you can make it wider.
If you plan to insert a connecting tin box inside the channel, then it is best to make a channel with a cross-section of 20 by 20 cm.
To extend its service life, a brick chimney is installed along the internal wall of the house. The fact is that the durability of such a pipe is directly related to the high temperature of the smoke.
When temperature changes, the brick will begin to collapse. Additionally, maintaining proper temperature ensures better traction.
Ceramic pipes
Making a chimney from ceramic pipes is easier and faster to install yourself. This type of chimney is considered the most durable.
The smooth inner surface of the pipe reduces the chance of soot settling on it and makes cleaning the chimney easier.
Some pipes are equipped with condensate drains, which prevents condensation from forming on the inner surface of the pipe.
The chimney itself is assembled from parts 0.5 - 1 m long. The upper edge of each part has a coupling - an extension into which the next part is inserted.
Ceramic pipes can be of different types:
- round ceramic pipes for installation in special concrete blocks;
- rectangular pipes for installation in brick;
- ceramic pipes in a steel casing;
- ready-made blocks with ceramic sleeve.
To make a pipe from round ceramic links, you need to purchase special reinforced concrete blocks.
They provide a cavity for installing ceramic pipes and seals. In addition, they have holes into which reinforcement is inserted during installation.
Concrete modules with an additional ventilation duct are available. Asbestos is used as a sealant when installing pipes. It helps protect nearby surfaces from fire.
Rectangular ceramic sleeves have a square cross-section of 20 by 20 cm and are designed for installation in a brick pipe.
The length of each individual section varies between 0.5 - 1 m. They are mounted in the same way as round ones, only you do not have to buy special blocks to install them.
Ceramic sleeves in a stainless steel housing are even easier to install.
Such a chimney is much lighter than a ceramic or brick one, so a foundation is not necessary. Pipes in a steel shell are connected to each other using clamps.
Ready-made concrete blocks are also available for sale, already equipped with a ceramic liner, a ventilation duct and holes for reinforcement.
Coaxial chimney
Unlike all the types described above, the coaxial chimney for a gas boiler has a horizontal outlet.
The convenience of such a chimney is that it is exhausted through the wall, and not through the roof, like a vertical chimney. To install it, simply drill a hole in the wall.
Such chimneys are designed according to the “pipe-in-pipe” principle. Here the possibility of supplying air to the boiler burner and removing smoke is immediately provided.
However, in our climate, a coaxial chimney for a gas boiler has one significant drawback. During the cold season, the air entering the burner significantly cools the exiting smoke.
As a result of temperature changes, condensation occurs. Freezing occurs on the outside of the pipe, which gradually clogs the passage and reduces draft.
Modern gas boilers are equipped with automatic shut-off, so carbon monoxide poisoning due to reduced draft does not threaten anyone.
But in order to resume operation of the boiler, the pipe will have to be cleaned of the ice that has formed in it.
Fewer problems arise with chimneys that use two separate pipes for air supply and exhaust. But such pipes are rarely found on sale.
Stainless steel pipe
The chimney is made of thick stainless steel and can be either vertical or horizontal. Installing such a pipe with your own hands is quite simple.
Disadvantages of a steel chimney:
- the service life of such a pipe is shorter than that of a brick or ceramic chimney;
- the cost is higher.
The advantages are simple, quick installation and lightweight design. A stainless steel pipe does not require installation of a foundation.
Since it is light in weight, it is suitable for wall mounting. Their inner surface is absolutely smooth, thanks to which soot almost does not appear.
If such a chimney becomes clogged, it can be easily cleaned and, if necessary, can be disassembled. Replacing used parts is also not difficult.
Stainless steel pipes can be either single-walled or double-walled, with insulation between the walls. It is better to use just such sandwich pipes.
Stainless steel chimneys can be used in rooms where a smoke exhaust pipe is not even provided for in the design. In this case, it is enough to lead the pipe to the street through the wall.
Single-wall steel pipes are used when converting an existing chimney for a gas boiler.
The connection of the gas boiler to the chimney occurs through a steel pipe, which is led into a brick pipe and fixed there.
How to choose the type of smoke exhaust structure?
To make the right choice, first of all you need to familiarize yourself with what requirements the manufacturer sets for the chimney.
When choosing the type of chimney for a specific boiler model, you must be guided by the following parameters:
- temperature of the exiting smoke;
- pressure and type of traction;
- the presence of channels for condensate drainage;
- recommended requirements for the distance to kitchen furniture and other household items.
Based on the combination of all these characteristics, you can choose which type of chimney is suitable. In addition to these parameters, each manufacturer has its own requirements for the required channel cross-section.
The diameter of the chimney for a gas boiler can only be determined by deciding on a specific model. Therefore, it is not advisable to arrange a smoke exhaust duct in advance.
In addition to the characteristics of the gas boiler, it is also necessary to take into account the characteristics of the building. It is not advisable to install a brick chimney in a panel country house or in a frame building.
For light buildings, a stainless steel or coaxial chimney is best suited. In addition to the fact that these types are relatively light in weight, they are easier to install with your own hands.
The following requirements apply to the chimney itself, regardless of what material was used in its construction:
- absolute tightness;
- presence of traction;
- vertical location of the outlet channel;
- if a vertical position is not possible, then the slope angle should not exceed 30°;
- smoothness of the inner surface of the pipe;
- presence of a hatch for cleaning;
- ability to reduce cravings;
- insulation of external areas.
The smoke duct must be completely sealed. Even a small amount of gases can cause poisoning.
To avoid this, it is necessary to check the channel for leaks and the presence of traction. The slope of the pipe from the vertical can be a factor that reduces traction.
The inner surface of the channel should not contribute to the accumulation of soot on its walls, for which it is necessary to check its smoothness.
This is especially true for brick chimneys, since in other types this problem occurs less frequently. The seams between the bricks must be perfectly even. You can also use a pipe insert.
Many people think that the smoke exhaust shaft starts from the boiler. This is wrong. The channel should fall below the boiler outlet by 30 - 50 cm.
This is necessary for installing a wall hatch, which will be used to clean the channel. Using it you can check the traction.
In some cases, it may be necessary to limit cravings. To do this, it is recommended to install a damper in the channel above the boiler.
A damper device is only necessary if the boiler is not equipped with a built-in damper. The damper can be replaced with an automatic limiter.
The greater the power of the gas boiler used, the larger the cross-section of the chimney duct and the height of the pipe should be. This will ensure good draft and proper operation of the boiler.
Security
During gusty winds, air from outside can enter the chimney, blocking the draft. In this case, if the boiler is not equipped with an automatic switch, the room will become smoky.
The same thing can happen during heavy rain or snowfall. To avoid the influence of atmospheric phenomena, the chimney outlet is covered with a special umbrella.
You can make an umbrella for a steel pipe from any piece of metal. You can also make a head for a brick channel.
The head structure provides smoke outlets from the side of the pipe, and the top itself is covered with a brick or plate.
Since most often the chimney is the highest point of the roof, it is worth thinking about making proper grounding - a lightning rod. Any metal structures have an increased degree of lightning hazard.
If the chimney is made of brick, then the lightning rod is manufactured as follows:
- metal fittings are mounted to the wall of the smoke duct;
- the fittings are connected by wire to the grounding system of the roof of the house;
- The grounding cable goes to a metal plate that is buried in the ground.
This grounding scheme can also be used when the smoke duct is made of metal. In this case, the role of the lightning rod is played by the metal head of the channel.
However, such grounding is only possible if the boiler is not equipped with an electronic processor.
To prevent the electronics from malfunctioning, the lightning rod should be made separately, at a distance of at least 50 cm from the chimney.
This grounding scheme provides that:
- when connecting the smoke exhaust duct and the grounding pole, no conductive materials are used;
- The lightning rod is located above the chimney.
To properly make a grounding system, you should use reinforcement with a cross-section of at least 10 mm.
When installing a smoke duct, you also need to worry about fire protection. The fire protection scheme provides for a 5 cm indentation when passing through the ceiling, which is filled with asbestos.
Fire safety rules require a minimum distance of 26 cm from walls, furniture and other objects that may catch fire.
Happy construction!
Gas ducts in an apartment building or private building are considered an essential element of ventilation. The exhaust structure of the chimney can be external or internal. The chimney device has different designs. At the same time, it is important to know what sizes, types, and standards for drainage channels there are.
The hood is used for forced ventilation. Its design includes an air intake that tapers to a bell. The latter is mounted to the pipeline. This mechanism can be found above the plates. For the heating system, a similar system is implemented, but the execution is different. For a gas boiler, the chimney plays the role of an exhaust hood.
The need to install a chimney:
- Removing gas combustion products and preventing them from entering the house;
- Draft for oxygen to enter the system;
- Effective use of the system.
But these functions will be provided with proper installation of the system. All installation and commissioning work must be agreed upon with the gas service. But when using a gas cylinder, you do not need permission from the service. But during inspections, violations may be found and the system will be prohibited from operating.
Types of chimneys for gas boilers
The chimney for the boiler creates optimal and safe working conditions by removing combustion products. But before installation, you need to select a scheme and installation option. Chimneys are divided depending on the material of manufacture.
Types of chimneys:
- Made of brick. To install it, a foundation is required, so installation of the system is carried out at the design stage of the house. The inner coating of the pipes must be sufficiently smooth. And the brick itself is resistant to aggressive vapors.
- Made from stainless steel. The material is resistant to chemical and mechanical influences. The system appears to have a sandwich design. A product with a smaller diameter is mounted into an external stainless steel pipe.
- Coaxial design. This is a split chimney where the pipe fits into the pipe. Oxygen for combustion enters through one, and combustion products exit through the other. Thanks to this, the efficiency of combustion and fuel use increases. Moreover, this design is considered environmentally friendly.
- Made of ceramics. These look like heat-insulating ceramic blocks mounted in a concrete base. A ceramic chimney has many advantages, but the main thing is to connect the modules correctly.
We suggest studying the advantages of installing coaxial type chimneys:
Certain pros and cons apply to each specific case. The main thing is that the design complies with building codes and regulations. SNiP prescribes the correct installation of any type of chimney.
Standards and requirements for a gas pipe in a private house
All work with the chimney, from design to installation, is strictly regulated by building codes. All information is specified in SNiP 2.04.05-91 “Heating, ventilation and air conditioning”. If these rules are neglected, the pipeline will prove dangerous during use.
Main regulatory requirements:
- Good draft will ensure rapid removal of combustion products;
- Thermal resistance;
- All connections must be treated with sealant;
- The section of pipe through the roof must be solid;
- To collect and remove liquid, a condensate collector is provided in the system;
- If there are turns, you will have to equip inspection hatches, which will help monitor the condition of the chimney;
- The optimal length of branches should not be more than 1 m;
- The number of turns is no more than 3;
- For good draft, the chimney pipe must be higher than the roof structure;
- The distance between flammable materials is 25 cm, non-flammable - 5 cm.
The gas boiler is most often located in a separate room -. All connections are assumed to be tight. All other installation rules are described in the above standards.
The tightness of the connections will ensure the insulation of the structure, and combustion products will not leave the system.
The chimney elements include a flue, pipes, inspection and connecting elements. The flue is a channel that is located at the junction of the boiler and the pipe. The revision is used to clean the structure. It is located at the bottom of the chimney.
Find out about the correct choice of pipes for the chimney and the features of manufacturing a smoke exhaust system:
The sequence of installing a chimney for a gas boiler in a private house
There are internal and external installation systems. It all depends on the stage of design planning. When building a house, the internal system is performed. In prefabricated buildings, the external structure is performed.
The external system is characterized by the need for complete thermal insulation of the chimney. To do a good job, you will need to follow all the rules and regulations. Elements of the same type are selected for the design. Their connection is quite simple. At the same time, the system is freely accessible for maintenance.
When installed internally, the system must be installed in a strictly vertical order, without deviations in the diameter of the pipes.
The internal structure requires thermal insulation only in the area that is located on the street. The system is unsafe: smoke can enter the room, there is a high fire hazard. The number of structural elements is quite large, so installation has certain difficulties. Operating a chimney also has its difficulties.
Consistently internal installation:
- Marking the structure and connecting elements;
- Equipment for the chimney opening;
- Connection of the boiler to the flue through a special pipe;
- Installation of revision and tee;
- Pipe installation;
- Attaching clamps at joints;
- Installation of brackets;
- Thermal insulation.
The internal system is installed during the construction of the house and the construction of the foundation. This is how you can make a safe structure. Due to this, the amount of liquid in the pipes is minimal. Otherwise, you will need to equip a condensate collector.
How to properly install a chimney on a gas boiler
The chimney installation must comply with building regulations. Otherwise, problems will arise with the operation of the structure. All installation features are taken into account in a number of rules and recommendations.
Installation Tips:
- The maximum pipe slope is 30 degrees;
- To remove condensate, it is necessary to install a condensate collector at the bends of the system;
- You should think about the marking of the drip and revision in advance;
- It is mandatory to install dampers to stabilize traction;
- On the street it is necessary to insulate the pipe;
- When joining elements, there should be no cracks or gaps;
- The joints will need to be well sealed;
- The pipe installation must be in a strictly vertical position;
- For insulation, you can use mineral wool, and install a brick layer on top of it.
In addition, special attention should be paid to the material used to make the chimney. It is best to choose fire-resistant elements. The pipe itself must be smooth; bends and irregularities are not welcome. Before starting work, you will need to thoroughly inspect the integrity of the structure. Pipes must be smooth and even.
The main cause of chimney failures is the presence of condensation. At the design stage, it is important to consider the drainage of liquid from the pipe.
The internal structure of the pipe must be freely accessible for cleaning and repair work. If you deviate from the standards, the gas service may prohibit the use of the boiler. It is important to approach the installation process correctly and responsibly.
Stages of installing a pipe for a gas boiler
First, equipment is purchased and all tools and materials are prepared. Also, a project, diagram and all calculations must be prepared in advance. After this, you can build a veterinary channel.
How to build a chimney:
- First, preliminary assembly of the structure is carried out to ensure the integrity and completeness of the materials;
- The chimney is then connected to the gas boiler;
- All structural elements must be fixed with connecting parts;
- The system is then checked for leaks.
The outer pipe is discharged from the boiler room through the wall. Sometimes they can use ready-made ventilation or a window. You will have to make a hole in the wall of the required diameter for the pipe and thermal insulation.
There is no need to rush the hole. First you need to make sure the calculations are accurate.
One section of pipes is inserted into the resulting hole, secured and insulated. On the street, sections are gradually added and a plumb line test is performed. Using brackets, the chimney is attached to the wall. The end of the chimney is equipped with a roof.
Fighting liquid: condensate collector for the chimney
A condensate trap is a special compartment in a pipe where liquid accumulates. But you can reduce the amount of condensate in other ways. Therefore, only dried fuel should be used.
Smoke must move freely through the pipes, so the walls of the chimney must be smooth and even, with a minimum number of bends.
Proper operation of the pipe requires regular cleaning of soot and contaminants. Additional devices are also welcome. You will need to install a protective cap, a collector, a limiter and a diverter.
If the temperature of the gases exceeds 100 degrees, then the condensate will not settle on the walls of the chimney, but will simply evaporate. Compliance with the standards guarantees the effective use of the chimney. All dimensions and locations of pipes should be adhered to.
Types of chimneys for a gas boiler in a private house (video)
A chimney is needed for any AOGV boiler. It doesn’t matter whether the installation is carried out internally or externally, but basic standards and GOSTs should be observed in everything. The ventilation ducts of a wall-mounted gas boiler must be well insulated and insulated.
Examples of chimneys for a gas boiler (photo)
Does a gas heating boiler need a chimney? Of course! Is it possible to build a chimney for a gas boiler with your own hands? Certainly! You just need to study the design features of the most common types of smoke exhaust structures, familiarize yourself with the key requirements for such systems and carry out everything in full accordance with the provisions of the manual.
Features of the chimney device
Regardless of the type of chimney chosen, it will include the following components:
Different materials can be used to make a chimney. Check out the features of the most common solutions and make your choice.
If we judge objectively, then a brick chimney is not even the last century, but the century before last. Such a smoke exhaust system has a complex design and requires serious time, labor and financial costs for arrangement.
In addition, a brick chimney will be inferior to its modern “brothers” in many significant indicators.
Chimney made of galvanized pipe
The sandwich-type design made of pipes is rightfully considered one of the most effective and successful options for smoke exhaust devices.
Today, manufacturers offer a huge range of such chimneys. Among their advantages, it is necessary, first of all, to note their resistance to aggressive external influences and various mechanical loads.
First step . We connect the adapter to the unit pipe.
Second step. We install the tee and revision.
Third step. We begin to build up the chimney.
If necessary, we carry out work using the so-called. knees Where the pipe crosses the floors, we use a special protective pipe.
Fourth step. We put a stainless steel sheet on the chimney. We cut out a hole in the sheet in advance, slightly larger than the pipes. Such a sheet should be located on both sides of each floor.
Fifth step. We strengthen the joints of the structure with clamps.
The popularity of using gas heating boilers is due to a number of advantages of natural gas over other types of fuel. But gas, while making it easier to solve the heating problem, is a high-risk fuel, so the requirements of regulatory services to ensure the safe operation of gas boilers, like any other gas-powered equipment, are also increased.
The chimney is an integral element of the design of any heating unit, the principle of operation of which is based on the combustion of fuel. A gas boiler is no exception. When gas burns, visible smoke that is not familiar to the eye is formed, but carbon monoxide is a colorless and odorless compound that is deadly to humans, requiring direct and complete removal to the outside, which is what the chimney pipe for a gas boiler does - an independent structure or an integral part of the overall smoke exhaust system from housing.
General requirements for chimneys of gas boilers
- complete sealing of the chimney channel throughout its entire length;
- the presence of sufficient draft to completely remove combustion products from the boiler;
- fire resistance and chemical resistance of the material used on the inner surface;
- high temperature resistance;
- each boiler is equipped with a separate chimney;
- the smoke channel along its length should not have more than 3 turns, and the ovals in the configuration are made with a radius of curvature no less than the diameter of the outlet pipe;
- the vertical chimney must be at least 5 m in height - the minimum value that provides the necessary vacuum and draft;
- the diameter of the chimney pipe for a gas boiler should not be less than the size of the outlet channel of the heating unit;
- inadmissibility of connecting chimneys to ventilation ducts;
- compliance with regulatory requirements:
When installing a chimney, it is also necessary to take into account the dependence of its parameters on the power of the gas boiler, set out in regulatory documents, but more clearly presented in the table:
Options for the location of chimneys for gas boilers
According to the location of their installation, chimneys are divided into:
- internal;
- external.
These types of chimneys are devices whose main structure is located vertically.
An independent type of chimney is a coaxial pipe, in which combustion products and air from the street move towards each other in the channel.
Both types of chimneys are arranged taking into account the requirements of the above regulatory documents, but have individual design features that determine their advantages and disadvantages.
Internal chimneys
A chimney installed inside the building's contour, limited by the outer walls, is called internal.
The outer walls of the pipes of such a chimney for a gas boiler are not exposed to the negative effects of the external environment (temperature changes, precipitation, ultraviolet radiation, wind, biological factors), so the design is durable.
In addition, during the movement of hot combustion products through the channel, heat transfer into the air of the home through the walls of the chimney continues - the side surface of the chimney is an additional source of heat, therefore the efficiency of such a heating system is higher, especially in 2-story houses.
However, this arrangement of the chimney also has disadvantages:
- in case of depressurization of the chimney, carbon dioxide will leak into one of the rooms;
- overheating of the channel surface poses a risk of fire;
- the places where the chimney passes through the floor slabs need thermal insulation;
- The shaft or chimney pipe occupy a certain area and volume in the premises, so the factor of their presence must be taken into account when rearranging furniture and choosing finishing materials.
If the internal chimney is installed during the construction of the house, then there are no problems with its construction - the project contains everything necessary for execution, including the technology for manufacturing an individual foundation for it. If a decision is made to build a chimney of this design in an already built house, then its installation is associated with significant expenditures of time and money, since it will be necessary to make openings in the floor slabs, and this will damage the existing finish.
External chimneys
A chimney attached to the wall of a house or brought out through a side wall is called an external one.
Advantages of this location:
- simplicity of construction - the possibility of installation in an inhabited house without compromising the finishing;
- efficiency;
- ease of maintenance and repair;
- safety - depressurization does not threaten poisoning.
Disadvantages of outdoor chimneys:
- the need for insulation - to prevent the formation of condensation on the inner surface of the walls;
- exposure to negative environmental factors;
- a lower efficiency value means the inability to use the side surface as an additional heat source.
Summary table of characteristics of internal and external chimneys: 
Coaxial chimneys
These devices are especially popular when equipping a gas boiler with a closed combustion chamber with a smoke exhaust. A coaxial chimney is a pipe within a pipe in which two processes occur simultaneously - the entry of air from outside into a closed combustion chamber and the removal of combustion products from the inside to the street. The coaxial pipe can be used both on wall-mounted boilers and when installing a chimney for floor heating units. The location of the channel can be internal or external, orientation - vertical or horizontal.
Installation consists of making a through hole of the required diameter in an external wall, floor slab or roof according to pre-made markings, installing a pipe into it and filling the gaps with heat- and moisture-resistant sealant.
Types of chimneys based on materials of manufacture
Chimney pipes for a gas boiler are made of the following materials:
- brick;
- ceramics;
- steel;
- combination of materials.
Brick chimney
The ideal cross-section of a pipe through which smoke passes at the highest speed is a circle, and it is irrational to lay out a chimney with a round cross-section made of brick. In addition, the brick needs to be fire-resistant, but this does not save the channel walls from fouling with soot and destruction due to the influence of condensing acidic components of gas combustion products. Therefore, chimneys for solid fuel heating boilers or stoves made of identical material are laid out of brick.
The process is labor-intensive, as well as the need for careful selection of heat-resistant bricks and a binder with heat-resistant characteristics.
Construction begins with the construction of a strong individual foundation inside the building’s contour without a rigid connection with load-bearing walls and floor slabs. It is not advisable to carry out this work yourself, without having the skills to work in laying furnaces, but knowledge of the technology will help control the work of a professional performer.
One of the conditions for ensuring sufficient traction is the required amount of elevation of the pipe head above the roof ridge, depending on the location. The diagram demonstrates this better than the description.
But the presence of draft, nevertheless, does not completely eliminate the factor of the destructive effect of smoke, its acid-forming components and condensate on the brick.
The influence of these factors can be eliminated by installing a chimney from a steel pipe and covering it with refractory bricks. The ideal channel material is stainless steel, resistant to chemically aggressive substances and moisture.
Based on the nuances of using brick when constructing a chimney, its use for equipping a heating system based on a gas boiler is not justified.
Chimney made of ceramic pipes
The ceramic smoke exhaust pipe is a prefabricated structure. The outer body is a load-bearing frame made of lightweight concrete. There is a ceramic pipe inside it. The space between the inner and outer layers is filled with a special heat-insulating material.
A ceramic chimney is assembled from individual elements 20-60 cm long, having a connecting shaped socket at one end, which during assembly is treated to seal the joints with an acid-resistant adhesive.
The ceramic channel is insulated from the outside with heat-resistant thermal insulation and lined with hollow expanded clay concrete blocks or heat-resistant bricks with cement mortar. Grooves in the blocks promote ventilation of the insulation and neutralize thermal expansion of the ceramics. The design and profile of the blocks can be different - depending on the diameter of the chimney and the number of ceramic pipes in the channel.
To facilitate installation, manufacturers offer ready-made kits of ceramic chimneys, which include all the necessary fittings and have a guaranteed service life of 30 years or more.
Installation of a ceramic chimney
Ceramic chimneys are rarely installed outside, since the external design will require an additional reinforcing shell made of bricks or blocks.
The device begins with determining the exit location of the channel in the roof. Then they project this place down with a construction plumb line, remove the soft soil, plan the site, mark the contour of the foundation and make a crushed stone backfill.
Foundation
If the base for the chimney is the foundation of the house (the structure is a cushion) or a concrete floor with reinforcement, then the installation of the duct is carried out on it, having previously waterproofed the site.
The dimensions of the foundation in plan and its depth depend on the properties of the soil and the parameters of the chimney - sectional contour and weight (number of floors of the building).
Important! The foundation for the chimney is constructed independently; it should not have connections with the base of the building.
Formwork is installed along the contour marked on the ground, after which reinforcement is made - a mesh of variable profile reinforcement with a diameter of 10-12 mm is laid, connected with a knitting wire to a cell of 10x10 or 12x12 cm.
The foundation is poured with concrete of a grade not lower than M-200. A week after installation, it will gain 70% strength, and you can begin laying the chimney by waterproofing the area under it (roofing felt, bitulin).
Installation of blocks
Ceramic elements are laid in accordance with the design of the installation joints; a heat-resistant compound is applied to the joints of the elements before installation, which not only firmly fixes the joint after curing, but also seals it. It is convenient to lay the composition with a mounting syringe, or, if not available, with a trowel. The excess mixture that comes out after installation is immediately rubbed down with a piece of foam rubber flush with the joint - there should be no drips or bulges.
Important! It is prohibited to “revive” a prepared but already hardening composition by adding water and stirring - a significant part of the strength of such glue will be lost.
The laying of the supporting frame is carried out depending on the design of concrete or brick blocks, which are made either solid with an installation hole in the cross-section, or detachable, laid around the pipe.
In the lower tier, the first module should be located with a device for collecting and draining condensate. To do this, use a grinder to make a slot in a concrete or brick block to bring the outlet pipe out. A solution is applied to the base, the mounting area of the product is wetted, and the block is placed in place, after which a ceramic module with an outlet pipe is installed in it, also on the cement mortar.
The verticality of the mounted sections is controlled by the building level. When laying the walls, it is also necessary to provide for the location of inspection hatches and connections for the outlet pipe of the gas boiler in order to mount these elements in areas corresponding in height with the desired orientation.
Thermal insulation is laid around the pipe by inserting it from above into a block installed on the solution with preliminary adjustment of the dimensions.
Important! Horizontal joints of ceramic modules and hollow concrete blocks of the supporting frame when passing through the floor slab should not be located in its plane - a solid element should pass through the slab, equipped along the perimeter of contact with it with a heat-resistant elastic sealant that neutralizes possible deformations.
To enhance the strength of the outer load-bearing frame, the blocks are provided with through holes - reinforcement channels, which must be aligned during masonry production. Before the solution hardens, pieces of steel reinforcement of variable profile are inserted into these holes so that the joints of the rods with each other fall in the middle of the block, and not at the seam. The diameter of the reinforcement is selected so that after installing the rod there is space left in the reinforcement channel to fill it with liquid cement mortar. The reinforcement is straightened and cut into pieces that allow 2-3 blocks to be fastened together.
The external seams between the blocks or bricks of the supporting frame are also carefully rubbed, and excess mortar is removed before curing, so that subsequently there is no need to knock on the channel to remove it.
The cross-section of a ceramic chimney for gas boilers with a closed combustion chamber is somewhat different - in the supporting frame blocks there is a separate channel for air supply to the burners, which, like the reinforcement holes, must be carefully aligned during installation, but the technology for laying structures is identical to that described above.
The top of the pipe must be equipped with a protective cap to prevent moisture and foreign objects from entering the chimney. The aerodynamics of the exit of gases depends on the shape of the head, so it is better to install an industrially produced product rather than experiment with homemade crowns.
The finishing of the outer surface of the chimney in the premises is carried out depending on the interior of the home; the most practical is cladding with ceramic tiles with appropriate temperature characteristics.
Advantages of a ceramic chimney:
- the inner surface of ceramic pipes is covered with a layer of heat-resistant glaze, which, unlike brick, does not contribute to the deposition of soot - one of the conditions for good traction;
- the glaze is waterproof, which prevents the pipe from absorbing condensate and destroying the walls when it freezes - condensing compounds flow down into a special sump, which ensures the strength of the chimney body;
- low intensity of soot layering - practically no soot settles on a smooth surface, and most of it flies into the atmosphere along with smoke;
- ease of maintenance - soot is removed from smooth glazed walls much easier than from brick walls;
- fire safety - even if there is a certain amount of soot in the pipe, its ignition will take place without consequences, since ceramics are heat-resistant and have low thermal conductivity;
- resistance to chemicals - ceramics do not interact with acids formed during condensation of moisture and gas combustion products on the walls of the pipe;
- durability;
- ease of processing - ceramic chimney elements do not require special tools.
Disadvantages of ceramic channels:
- significant weight of the structure;
- the need to build a foundation;
- high price;
- the need for precise fitting skills.
Ceramic chimney in a steel casing
This design is a more advanced version of the previous device produced in Germany. The inner part is made of ceramics, and the outer shell is made of steel elements 60-100 cm long, assembled into a solid structure using special crimp-type fasteners. Installation is simple and can be located anywhere, including installation inside a wall - rectangular systems are produced for this purpose.
Despite the many advantages of a ceramic chimney in a steel shell, this material has a significant drawback - its high price, which prevents the growth of its popularity when used in everyday life.
Steel chimneys
For the manufacture of such channels, ordinary or stainless steel with a thickness of 0.5-0.8 mm is used. The advantages of stainless steel in this case are obvious - durability due to resistance to acids formed when nitrogen and sulfur components of smoke come into contact with condensate.
The degree of aesthetics of the design depends on the status of the building - cottages are equipped with channels made of stainless steel or with a colored enamel surface, fixed to the walls using decorative structures, country houses can be equipped with pipes made of ordinary steel painted with aluminum powder.
Pipe chimney systems are mainly located outside the home, attached to the walls using brackets of various designs, but internal placement is also possible provided the following conditions are met:
- pipe material – stainless steel;
- device of protective thermal insulation of the internal sections of the chimney to prevent burns from direct contact;
- construction of fireproof cutting around pipes at points of contact with walls and floor slabs;
- fulfillment of the requirements for the structural arrangement of chimney elements:
Installation
A foundation is not required for steel chimneys, and you can install them yourself.
Assembly is done from bottom to top. The design must include a sump for condensate with a pipe for draining it.
Prefabricated elements are connected to each other by shaped joints, the contact surfaces of which are covered with heat-resistant silicone sealant before assembly, which allows for spot repairs to dismantle the desired fragment. Crimping clamps are additionally applied over the joints.
The depth of installation of pipes on top of each other is determined by fire safety standards - no less than the radius of the mounted element.
It is allowed to have one horizontal section of pipe in the circuit, but with a length of no more than 1.0 m.
The pitch of the chimney mounting brackets on the wall is 1.5-2.0 m; each turning point (elbow) needs individual fastening to the base.
If the roof of the house is made of flammable materials, then a spark arrester deflector is installed at the end of the pipe.
To reduce the formation of condensation and increase draft, insulation is performed on the outer sections of the chimney with stone wool - a method that prevents it from getting wet. At the top of the pipe, where the insulation layer ends, a collar is installed on the channel with a downward slope around the perimeter to prevent moisture from entering the insulation from the end.
The part of the pipe facing the roof is attached to the base with three braces, evenly distributed around the circumference at 120 degrees.
Sandwich chimneys
Sandwich pipes are two steel shells of different diameters, between which a heat-resistant insulation of a certain thickness is placed. This design allows you to mount a chimney pipe for a boiler from elements that are already equipped with thermal insulation on the outside, so sandwich chimneys are equally suitable for both external and internal installation.
Based on the material used, sandwich pipes are produced in the following types:
- both shells are made of stainless steel;
- The inner pipe is made of stainless steel, the outer pipe is made of galvanized steel.
However, the resistance of steel to oxidation does not yet determine the degree of its suitability for use in smoke ducts.
The following types of stainless steel are used in the production of sandwich pipes:
- AISI 430;
- AISI 439;
- AISI 316;
- AISI 316i;
- AISI 304;
- AISI 321;
- AISI 310S.
The most inexpensive materials are steel grades AISI 430 and AISI 304, but their application is appropriate - only for external shells. The highest quality are AISI 316i, AISI 321, AISI 310S, used for both external and internal pipes, and this must be taken into account when choosing a material.
The grade of steel used has a significant impact on the cost of pipes. Therefore, when looking for the best offer, you need to take into account the material of manufacture. A conscientious manufacturer always supplies its products with labels indicating the grade and thickness of the stainless steel of the internal and external contours. The dependence of the cost on the grade of steel is clearly demonstrated in the summary table of prices for stainless steel chimneys on the official website of the ROSSTin company.
Installation
The construction of an external sandwich chimney begins with the installation of a starting unit on the outer wall of the building. At the starting unit, the first element of the sandwich chimney is installed - the support plate.
A tee is installed on the support plate, from which the vertical part of the chimney is installed, and an inlet hole is made in the wall according to the markings with calculations to equip the entrance with a fireproof passage and thermal insulation.
The fragments are attached to each other by inserting ends into each other, made in compliance with the required landing diameters. Crimp clamps are installed over the landing joints. But when installing pipes, two methods of their orientation are used - “along the smoke” and “along the condensate”.
When installing sandwich pipes, the following rule must be followed:
- the assembly of the horizontal section up to the tee is carried out “by smoke” - the next fragment is put on the previous one;
- the vertical section of the chimney is collected “by condensation” - the next fragment is inserted into the previous one.
Both methods of mating must be performed using sealant.
After installation, the upper part of the chimney is attached to the base with braces using a special clamp and eyes.
Self-installation of a sandwich chimney is simple only at first glance. In practice, this operation requires professional skills to perform many types of work, including at height. In addition, not only the efficiency of the gas boiler, but also the safety of the people living in the house depends on the quality of execution and compliance with technical standards. Therefore, it is recommended to undertake the independent installation of a sandwich chimney, which includes many small but important nuances, only with the participation of a professional mentor.
Conclusion
Installing a chimney for a gas boiler is a very responsible procedure, and taking into account the cost of materials for modern designs, it is quite expensive to undertake without knowledge of the technology and skills in performing roofing, construction, installation and finishing work. However, knowledge of the operation algorithm and the basic requirements for chimneys will facilitate ongoing monitoring of the work by a professional contractor.
