Height and diameter of the chimney for solid fuel boilers. Selecting a chimney for a gas boiler: types, calculations, step-by-step installation instructions Diameter of the exhaust pipe of a gas boiler

From the article you will learn how to install a chimney for a gas boiler in a private house, about external and internal chimneys, about chimney elements, about coaxial chimneys, about the features of a condensing gas boiler that does not use conventional chimneys, about brick chimneys and about the correct installation of a chimney .

Why do many people choose gas heating these days? Yes, because it is the cheapest type of fuel.

Once you have decided on the choice of a gas boiler, you should also think about removing the “waste” gas from the room. What should a chimney be like for a gas boiler? The Fire Inspectorate has very high requirements for these structures, so approach the work consciously and responsibly.

Selecting the overall dimensions of the chimney

The gas boiler chosen for heating a private house must be available to you, only after that you can select the correct chimney for the gas boiler and calculate its dimensions (see).

The height of the chimney depending on its location relative to the ridge of the house

Attention. If there are extensions above the house or it is planned to build them in the near future, then it is necessary to build a pipe that extends beyond the adjacent building.

Variations with chimney length

By selecting the required diameter and length for the chimney pipe and calculating its usable area, it may turn out that this same area will be less than the internal area of the gas boiler. If you change the pipe diameter to the next one (all pipes are produced in standard diameters), then with the same length you will get an excess chimney area and, accordingly, an excess consumption of material.

What can be done in this situation? Increase the length using a smaller pipe diameter. The table shows the minimum pipe heights. They can be increased, but not decreased.

After calculating the overall dimensions of the chimney pipe and purchasing the necessary building materials, you can begin installation.

Installation of chimneys for gas boilers

Immediately before starting work, you should determine the location of the chimney. There are 2 accommodation options:

When choosing the location of the chimney, you should understand:

location inside a private house will provide the structure with the most “comfortable” operating conditions;
the location behind the walls of a private house requires the presence of insulation to prevent the chimney from freezing; in this case, it is advantageous to use a sandwich pipe (the sandwich pipe has a multi-layer device, in the center of the sandwich pipe there is a layer of insulation).

Of course, the choice of location of the chimney for a gas boiler is yours. Check out the table below to help you make your choice.

Comparative characteristics of a chimney inside and outside a private house.

How to make a chimney for a boiler?

Installing a chimney for a gas boiler in a private house is not very easy.

Let's look at the basic principles of installing a chimney for a gas boiler.

It is necessary to correctly assemble all pipe elements.
In places where the smoke exhaust structure passes through the ceilings or walls of a private house, it is necessary to install special passage elements.
Insulation of all surfaces in contact with flammable materials.

Chimney elements of a floor-standing gas boiler:

adapter from the gas boiler pipe to the chimney pipe;
tee with inspection (at the bottom there is a fitting designed to remove condensate);
main fastenings - bracket and wall clamp;
bends, they are used at a distance of no more 2 m from the beginning of the chimney, otherwise it becomes possible to reduce the boiler draft;
feedthrough pipe;
telescopic pipes;
special tip having a conical shape

Please note that the tip for chimneys that remove “exhaust” gas must have a conical shape. It is strictly forbidden to install ordinary deflectors and umbrellas. It is allowed not to install the tip at all.

Requirements for the chimney of a floor-standing gas boiler:

the slope of some sections of the chimney is allowed no more than 30°;
maximum branch to the side - 1m;
the smoke exhaust duct device should not have ledges or narrowing of the cross section;
the maximum number of elbows that a structure can include is 3, the radius of curvature must be greater than the diameter of the pipe;
at turning points it is necessary to install a hatch for cleaning and eliminating condensation;
one side of a rectangular chimney should not be 2 times larger (smaller) than the other, i.e. the shape should not be elongated;
At the bottom of the chimney, an inspection and drip device is required;
Deflection of chimney elements is not allowed;
the pipe links are placed on top of each other by at least half the diameter of the pipe;
Any gaps between pipe joints are not allowed;
in places where the ceilings (roofs) pass, the pipe should not have joints;
all elements must be very tightly connected to each other;
the slope of the pipe towards the gas boiler must be at least 0.01°;
Roughness in the chimney is not allowed, the inner surface of the chimney elements must be perfectly smooth;
horizontal sections can have a total length 3m in buildings under construction and no more 6 m in built;
Below the connection point of the tee, a so-called “pocket” is required, with a length of at least 25 cm with a hatch (this will provide access to the pipe and the ability to clean it);
distance from the pipe to the structure (walls and ceiling) for flammable materials - 25 cm, non-flammable - 5 cm;
if the pipe passes through unheated areas of the structure, thermal insulation or installation of a sandwich pipe must be provided;
when removing “exhaust” gases from utility appliances, dampers (gates) should be provided;
it is necessary to bring the gate control to an accessible place with fixation of the “open” and “closed” positions;
If the device has a traction stabilizer, then dampers are not needed.

How to properly build a chimney for a gas boiler outside the house?

We attach a passage element to the pipe coming from the floor-standing gas boiler, which will pass through the wall of a private house.
After the opening is ready, we take the chimney out. The sandwich pipe section and the hole in the wall must be insulated.
We attach the tee with revision, put on the plug.
We extend the sandwich pipe by attaching links, attach it to the wall of the house with brackets, in increments of at least 2 m .
Having reached the estimated height of the chimney, we attach a cone-shaped tip.
We reinforce all sandwich pipe joints with clamps, which must be tightened with bolts or wire.
It is advisable to paint the pipe with heat-resistant paint, which will protect the material from corrosion.

If you do not want to use sandwich pipes as a building material for the chimney, then do not forget about the thermal insulation of the structure.

Installation of chimneys for boilers in the house

Let's start with the preparatory work:

We mark the holes for the chimney in the ceilings and roof.
Be sure to check the marked marks several times with the dimensions of the passage pipe. Cut out the required opening for the pipe.

Let's start installing the pipe:

A pipe comes from the boiler. We connect the adapter to it.
Next, we attach the tee and revision (for cleaning the pipes), attach the steel sheet and install the main bracket.
We extend the pipe, if necessary, use the so-called elbows.
When passing through ceilings, we use a special pipe.
We put a galvanized steel sheet on the pipe with a hole slightly larger than the diameter of the pipe. We attach the sheet to the ceiling on both sides.
We reinforce all joints with clamps secured with wire or bolts.
The chimney is secured using wall clamps (each 2 m) and brackets (each 4 m).
We complete the design with a special cone-shaped tip, which will protect the chimney from precipitation and wind blowing.

Insulation of chimney elements

All contacting parts of the chimney and flammable structure must be insulated. To do this, the passage pipe must be covered on all sides with a foil-coated basalt mat with fire-resistant mastic. Mineral wool insulation can be laid around the perimeter of the opening in the ceiling.

Upon completion of installation work, be sure to check the tightness of all seams in the structure. Make an ordinary soap solution and apply it to all chimney seams. If, after connecting a gas boiler to the chimney, you see bubbles, this indicates a leak.

Brick chimney for gas boilers

A chimney can be built not only from steel (certain grades), but also from brick. Or rather, the chimney will be located in brickwork, i.e. the chimney pipe can be metal, asbestos or ceramic. Visually, it will seem that the chimney is made of brick.

Why is it undesirable to build a chimney made of brick?

The fact is that brick is a fairly porous material that does not hold heat well enough. When gas burns, water vapor with various impurities is formed, which, in fact, must be removed from the room, and the construction of a brick chimney will contribute to the formation of condensation.

Chimney for condensing boilers

In general, the chimney of a condensing boiler differs little from the chimney of a conventional boiler, but there are some peculiarities. The chimney of a condensing boiler must be made of acid-resistant materials to protect against corrosion.

It is important that the chimney of the condensing boiler is located with a slope towards the heating unit. It is necessary that the condensate flows back, but that precipitation does not enter the unit. Raindrops can damage the condensing boiler.

Chimney for wall-mounted gas boilers

The most optimal building material for a wall-mounted chimney is double-circuit pipes.

A coaxial chimney consists of 2 pipes, which are inserted one into the other (see). This chimney resembles sandwich-type pipes, but without insulation between the pipes. This ensures the removal of “exhaust” gas and the flow of fresh air through the gap between the pipes.

Installation of such a chimney is quite simple. We attach a flow pipe to the pipe from the boiler and take the pipe outside. The distance from the chimney to the ground must be at least 2 m. When placing the chimney under a window, at least 1 m from the window to the ground level.

Gas boilers without chimneys

Gas boilers without a chimney are the last word in technical progress in this direction. The operation of the system as a whole differs from a conventional gas boiler. Let's not go deeper into this issue. The best thing about this system is that there is no need for a traditional chimney.

In any heating system it is necessary to remove combustion products outside the room. The difference is in the chimneys. In the new system, the chimney can be made of PVC pipes (the temperature of the “exhaust” gases is relatively low) with any number of turns; it no longer has to be strictly vertical.

The boiler operating temperature can be any. The unit runs on both natural and liquefied gas. In case of any problem it turns off automatically.

The information you have gathered will help you when installing a chimney with your own hands. If you want to use the services of professionals, then you will be savvy in the topic of chimneys for gas boilers. This will allow you to independently carry out supervision of the work being carried out.

Careful calculations must be made before purchasing materials.

Below we describe how to calculate a chimney for a gas boiler. Formulas for calculating the cross-section and power of the heater are presented. In addition, you will be able to superficially familiarize yourself with the types of materials used for the construction of chimneys and their designs, as well as the requirements for the exhaust system.

First, let's look at the materials of chimney pipes. Brick ones have not been used for these purposes for a long time. This is due to the fact that the smoke released during combustion has a relatively low temperature, about 150 degrees. Based on this, its speed in the system will also be low. The smoke has time to cool down to the dew point temperature and condensation forms along the internal diameter of the chimney of the gas boiler. Moisture has an extremely destructive effect on brick. If it is possible to use a brick structure for the above-mentioned type of equipment, then only with a liner inside. Prefabricated structures are the most widely used. These are metal double-circuit and three-layer pipes. Therefore, you should choose one of them as a pipe for the chimney of a gas boiler.

Requirements for the installation of a chimney for a gas boiler

there must be good traction;
reliability and durability;
corrosion resistance;
resistance of the exhaust pipe for a gas boiler to chemically aggressive environments;
ability to withstand high temperatures.

The height of the pipe depends on the cross-section and power of the equipment

In modern construction, only round or oval chimneys are used as outlets for fuel combustion products in heating systems. Almost no soot settles on their walls. It is also important that the surface of the internal diameter of the chimney pipe for a gas boiler is smooth. Structures with a square cross-section are more problematic to operate. Soot gets packed into the corners, then you have to get it out of there somehow, this causes a lot of hassle. Ideally, if you constantly use the heating system, you should inspect the exhaust pipe for the heating boiler twice a year. It is carried out by a knowledgeable person, a master. If the cross-section is round, then you can get by by calling a specialist only once a year.

Be sure to carry out preventive maintenance every year if we are talking about the house in which you live permanently. Call a professional before the start of the heating season. Otherwise, the soot, having accumulated, will reduce the diameter of the chimney for the gas boiler.

Types of combustion chamber designs

Before we move on to calculating the diameter of the chimney for a gas boiler, let's look at their types. The design of the combustion chamber matters more. The chamber in which combustion occurs may or may not be sealed. If it is not sealed, then oxygen to support the combustion process comes from the room in which the boiler is located. The heater has a special air duct in the lower part, through which air is supplied naturally. For such systems, only horizontal chimneys can be installed. These are metal double-circuit and ceramic sandwich pipes. If the design provides for the use of one chimney by two heaters, then the minimum height between chimney inserts for gas boilers should be more than half a meter. Even if the heaters are on the same floor.

Sealed combustion chambers take air from the street. For this purpose, a special chimney has been developed, which is called coaxial. The dimensions of a coaxial chimney for a gas boiler are much smaller than a conventional one. It is a metal pipe within a pipe. The smoke goes out into the street along the internal circuit, and through the external circuit it enters the boiler. To maintain circulation, a fan is installed at the top of the heater. This chimney can be installed both vertically and horizontally.

The standards for a chimney with a sealed combustion chamber provide for the installation of an individual outlet for carbon monoxide. It is impossible to connect two heaters to one coaxial system.

Calculation of chimney dimensions for a gas boiler

Calculations are carried out to determine the necessary parameters. What matters:

cross-sectional area;
The height of the chimney for a gas boiler is at least five meters, while the head must be at least half a meter higher than the roof ridge.

The draft depends on the correct calculation of the chimney diameter

Let's consider two possible options for calculating the chimney diameter for a gas boiler. The first option is when you have a heater and you need to calculate the cross-section of the chimney for it. Everything is very simple here. The ventilation should not be the same size as the stake pipe. Simply measure the smoke outlet hole at the top of the heater and you're done. If you cannot do this because it is not in stock, for example, when you ordered it and are waiting for delivery, the cross-section can be calculated based on the power of the gas equipment. In any case, you will know its characteristics. To calculate the cross-sectional area of the chimney, you need to multiply the heater power in kW by 5.5. The result will be calculated in square centimeters.

Before calculating the diameter of the chimney for a gas boiler, read the heater data sheet. For calculations, take not the thermal power, but the nameplate power. For example, for a unit with a nameplate power of 1.5 kW, the thermal heat can reach 38 kW. Insert a smaller value into the formula, otherwise you will be horrified by the result.

If you need to connect two gas heaters to one chimney, and this is allowed by fire safety standards, you should take into account the total power of both units.

The second option is when there is already a chimney. There is no need to calculate the diameter of the exhaust pipe of a gas boiler, since it can simply be measured. But you can find out the degree of productivity of equipment that is suitable for this system using the formula:

If the boiler chimney pipe diameter calculations are not done correctly, the hood will not work as it should. More than half of fires start due to a faulty chimney. Take this seriously.

The internal size of the chimney pipe should be either the same as the diameter of the chimney hole in the gas boiler, or slightly larger. Increasing the cross-section, of course, will affect the draft, but it will be there, and carbon monoxide will not enter the room.

Rules for installing chimneys for gas boilers

In order for the system to have good traction, the following technical requirements must be observed when installing a structure made of double-circuit pipes:

assembly is carried out from the heater;
the smoke channel must be smooth;
there should be no bends along the entire length of the chimney for a gas boiler;
to have good traction, it must be at least five meters in height;
two bends are allowed at an angle of 45 degrees and one at a right angle. Moreover, these segments should be no more than one meter;
the structure must be rigid, for this it is attached to the wall at a certain distance;
the umbrella should rise above the roof ridge by at least 50 cm;
Do not neglect the installation of additional elements, such as a moisture accumulator, a purifier and a head.

The parts of the metal sandwich pipe are fastened with rivets at the joints. Additionally, you can put on a clamp to hide the fasteners. Where the structure passes through walls and ceilings, a metal screen is installed. This is a square sheet of tin with a round hole in the middle. Special heat-resistant wool is placed into the resulting void between the warm lining of the chimney and the ceiling material. It looks like mineral wool, and foil is glued to both sides.

In the article “Installing a chimney for a gas boiler,” we looked at what kind of chimney is needed if a gas boiler is installed. In this article we will finish our discussion of installation technology and give an example of how to perform structural calculations.

Installation of the structure

Installation is carried out in several main stages.

Marking

At this stage, calculations are taken that indicate the cross-section of the chimney, its dimensions and height, and markings are applied in accordance with these parameters:

in floors and roofing pie – internal structure;
on the outer wall - an external structure or a coaxial chimney.

The correctness of the markings must be checked several times;

Cutting openings

Using a special tool, it is necessary to cut openings either in the wall or in the interfloor ceiling and roofing pie.

Connecting structural elements

We connect the boiler pipe to the adapter. We install the revision and tee. A special pipe is installed in the ceilings. Joints and external chimneys are strengthened with clamps at intervals of 2 meters and brackets at intervals of 4 meters;

Insulation

It is carried out using special heat-insulating materials.

Requirements for combustion product removal systems

Please note that if a gas boiler is installed, the chimney must meet a number of parameters:

We also note that the combustion product exhaust system must be warm; to ensure this condition, various heat-insulating materials are used.

In addition, the cross-sectional dimensions of the channel should not be smaller than the cross-section of the gas exhaust pipe installed on the boiler. For example, if the cross-sectional diameter of the outlet on gas equipment is 150 millimeters, then the cross-sectional diameter of the outlet channel should not be less than 150 millimeters.

Methodology for determining the main parameters

Different calculations are used for various gas equipment. Let's take the simplest option - a classic solid fuel stove, converted to run on natural gas (a gas nozzle is inserted into the firebox).

One of the key parameters for the functioning of any gas stove chimney is its cross-sectional area (measured in cm 2, denoted F).

The calculation is performed using the following formula:

F = (K ∙ Q) / (4.19 ∙ √ˉ N),

where, K – coefficient calculated empirically (equal to 0.02-0.03);
Q – degree of performance of gas equipment (see the technical characteristics that each boiler has);
H is the height of the chimney.

The obtained result must be adjusted in accordance with building codes and regulations. You can find them on the website or on the Internet. Type in the search query: “Technical conditions for converting stoves to gas.”

For example, if a stove or boiler has a brick chimney, then the calculation is performed with the condition that the cross-section should be ½ by ½ brick.

If asbestos-cement pipes are used, which is extremely undesirable, the diameter should be 100.00 millimeters.

Based on the above, we note that the calculation of the chimney, including the determination of such parameters as the height and cross-section of structures, depend on the location of gas heating and/or water heating equipment, the architectural features of the structure and the final technical characteristics that the stove has.

The calculation of a chimney for a gas boiler is influenced by a number of factors: the dimensions and layout of the room in which installation is intended, the model and technical characteristics of the device, the material and design of the pipes. Failure to comply with installation requirements violates fire safety standards and deteriorates the performance and power qualities of the boiler.

Coaxial chimney for gas boiler

Formula for calculating the optimal design

The formula for calculating the parameters of a chimney combines several conditions, each of which is calculated separately, analyzed and added to the marking scheme during installation. This formula shows:

flue gas movement speed;
chimney length;
sectional shape of the structure;
channel area;
room height;
chimney material;
average internal and external temperatures;
how much does free fall accelerate?
pipe wall smoothness coefficient.

For example, the pipe cross-section (F) in m2 is calculated using the following equation:

(КхQ)/(4.19х√ˉh)=F,

in which K is a coefficient (calculated empirically), Q is an indicator of the degree of performance of a gas boiler (power, kW, indicated in the technical data sheet of the boiler), and h is the height of the chimney.

To calculate the value of gravity (mm water column), the effective height of the chimney is multiplied by the difference between the air density and the density of the flue gases.

Calculation formulas identify new parameters and check the correctness of the calculation. This is how they check the correctness of the calculations of the dimensions of the chimney length using the formula:

P*L>S,

in which P is the perimeter of the cross-section of a square pipe, L is the length of the chimney, S is the area of the inner surface of the pipe. For a pipe with a round cross-section, the P indicator is replaced by I. I can be calculated using the formula I = 2пR, where R is the radius of the pipe.

Other indicators regarding the technical characteristics of the boiler, the gas supply rate to the device, which will be needed for calculations, are in the passport documentation.

Dependence of length on boiler power and pipe cross-section

Pipe material requirements

In addition to supplying air to the burner and good draft, the chimney exhibits:

corrosion resistance;
endurance under extreme temperatures;
resistance of the coating to aggressive chemical environments.

The indicators of these quantities are taken into account in the calculations and influence the choice of chimney material and the operating features of the gas boiler. So, the combustion products emitted by the device are at a low temperature (about 150 ° C compared to 300-600 degrees for solid fuel boilers) and the rate of their removal through the chimney is also low. The smoke cools down faster than it reaches the dew point and forms condensation inside the chimney. Therefore, important quantities for calculating the dew point are:

density of water vapor in combustion products;
fuel composition and moisture content;
excess air and temperature in the coefficient.

In addition, information about the technical data, materials and design of the pipes can ensure high performance of the chimney. The most preferred ones include:

ceramic;
steel (sandwich pipes);
condensation

It is impossible to use a brick chimney under a gas boiler: it does not resist condensation well and is destroyed under its influence, it is not sealed and provokes the leakage of combustion products. It is undesirable to use pipes with a square cross-section; they are inconvenient to use, accumulate soot, and distort the operation of the boiler. The optimal shape is a circle or oval with smooth inner walls.

Sandwich pipe

Installation location value

There is a difference between where the boiler is installed. The chimney is calculated for installation:

in a private house;
apartment building.

For private housing, vertical natural air circulation and forced draft are used. Another option for removing combustion products is to install a chimney with an exit through the wall (coaxial). For an apartment in a multi-storey building, the use of horizontal gas exhaust is permitted.

Depending on the area of the room:

if the dimensions of the room are less than 80-100 m2, it is recommended to install branches with forced draft;
in rooms with an area of more than 100 m2, a natural and forced system for removing combustion products is used.

Boiler installation in a private house

How does calculation affect installation work?

Calculating the chimney for installation is important, since this stage is fundamental and work begins with it. In addition to these nuances, SNiP requirements put forward several more points that are taken into account when arranging for the removal of combustion products during installation. These include:

2 gas channels can be connected to one chimney at a distance of at least 750 mm;
when assembling the pipe, a minimum number of narrowings, bends and horizontal sections are allowed (no more than 3 on one vertical riser), otherwise the traction will be disrupted;
the cross-sectional diameter corresponds to the dimensions of the outlet channel of the pipe located on the gas boiler;
the drainage system is made at a height of 5 meters and is insulated with insulating materials, the joints are treated with sealants;
in the drainage device, vertical deviations are allowed no more than 30%;
There is a condensate collector at the bottom.

Standards for the location of chimneys relative to their height

Alternative calculation methods

Even when correct calculations are used, gas boilers are operated correctly: do not overheat, do not set to maximum power, and are cleaned once a year. It is recommended to rely on the help of professionals for cleaning, installation and calculations.

They use consultations in centers where a gas boiler is purchased, which will provide detailed information with the installation requirements for the selected model, or use free online programs for quickly calculating chimney parameters (for example, EN13384, JEREMIAS).

In contact with

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.