How to make the right chimney for a gas boiler with your own hands? Chimney for a gas boiler in a private house: basic installation requirements Chimney pipes for gas boilers.

A hood for a gas boiler in a private house performs two main functions:

It is necessary for the efficient functioning of the equipment;
The combustion process occurring in it is impossible without a regular supply of oxygen.

Secondly, ventilation ensures the safety of people living in the house. The circulation of air flows prevents the accumulation of moisture, which, in turn, prevents the appearance of mold and fungi that are dangerous to health. In case of unforeseen situations, ventilation protects against carbon monoxide intoxication, fires and explosions. In this article we will look at what components make up an exhaust system for gas equipment and how to install it yourself in your home.

Low power boilers (up to 30 kW) can be placed in the kitchen if it meets a number of requirements:

the kitchen area is at least 15 m2;
the ceiling is located at a height of 2.2 m and above;
sufficient glazing (total window area) - at least 3 cm 2 per m 3 of the kitchen;
the windows are equipped with transoms and vents;
there is a distance of 10 cm between the gas device and the wall;
the walls are finished with fire-resistant material;
air flow is ensured through cracks, for example, at the bottom of the door.

In order for powerful devices (from 30 kW) to serve for a long time and at the same time be safe, experts strongly recommend equipping a separate room - a boiler room. Of course, not every room in the house is suitable for such purposes. Its volume should be at least 13.5 m 3 for devices with a power of 30-60 kW and at least 15 m 3 for 60 kW.

How to choose material for the hood?

For these purposes, brick, galvanized and stainless steel and ceramics can be used. Let's take a closer look at each of them, and also study what other options the market and engineering offer.

Brickwork hood

Although brick is used by builders when arranging ventilation, its properties do not allow them to save on other materials. Firstly, brickwork is not durable. The most comfortable conditions for her are constant contact with hot gases. Otherwise, condensation will form, which leads to its rapid destruction. Secondly, a brick chimney is labor-intensive to install, has a complex design and is unreasonably high in cost. Therefore, if you are faced with the task of arranging a chimney for a gas boiler, it is better to pay attention to other options. In this situation, a shaft is made of bricks. This same option can be chosen if for some reason heating the house with gas is currently impossible, but in the future it is planned to use it.

If brickwork is chosen as the material for the shaft, then the chimney itself is assembled from single-circuit galvanized pipes. The thickness of their walls is selected taking into account the temperature of the outlet gases.

Steel hood

In this situation, steel pipes are very convenient. They are easy to install when compared, for example, with brickwork. The wall thickness is selected depending on the heating. Gas boilers produce quite hot exhaust gas, about 400-450˚C, so the thickness of the walls should be 0.5-0.6 mm. However, there are pitfalls here too. Of course, steel is resistant to the negative effects of condensation. But on average, its wear resistance is much lower than, for example, the wear resistance of ceramic products. In addition, thin-walled pipes burn out quickly if used with solid fuel devices, so this option is not optimal when using different types of heating elements for different periods of time. Steel choose:

during reconstruction;
if there is no space for a ceramic hood.

Since steel ventilation ducts often spoil the exterior of a private house, they are covered with brickwork or other finishing materials.

Steel pipes are marketed in two variations - single-circuit and double-circuit. The second option is called a “sandwich” in slang. It consists of two pipes nested one inside the other, the gap between which is filled with fire-resistant basalt wool. The thickness of the inner pipe is determined by the temperature of the outlet gases (recall that this value is 0.5-0.6 mm for the devices discussed in the article).

“Sandwiches” are considered more economical among all steel hood options. This conclusion suggests itself if we take into account good thermal insulation, which increases the efficiency of the heating device.

Double-circuit steel chimneys are made of stainless and galvanized steel. Both metals are combined in “sandwiches”, since using only stainless steel is not economically feasible. The difference between galvanized and stainless steel is the latter’s higher resistance to condensation, which negatively affects its price. Otherwise, the properties of these two materials are not inferior to each other.

It is critically important that the internal part of the double-circuit structure is made of stainless steel; the material of the external part does not play a special role. This is due to the properties of zinc. Its heating above 419.5°C is dangerous. In this situation, the metal oxidizes, and further chemical reaction leads to the release of toxic fumes. Everything becomes even worse with high humidity, which cannot be avoided when commissioning a gas boiler. Therefore, when purchasing a sandwich structure, pay attention to this.

In principle, you can make a double-circuit chimney yourself without any special skills. To do this, wrap the stainless steel pipe in fire-resistant heat-insulating material. When choosing the latter, you can pay attention to basalt fiber, expanded clay or polyurethane. Then place everything together in a galvanized pipe of larger diameter.

Features of installing a steel ventilation column:

The segments are assembled using the “pipe to pipe” method in order, starting from the bottom;
For the convenience of subsequent cleaning of the post, provide a sufficient number of inspection wells;
For stability, wall brackets are attached in approximately 150 cm increments;
When designing, pay attention to the horizontal segments - they cannot be more than 1 meter long unless forced draft is provided.

Ceramic hood

This type of hood is the most versatile, so it is an ideal option if you plan to switch from or to gas fuel. They are easy to clean, resistant to dirt, due to their high gas density, and to aggressive chemical compounds, so you don’t have to worry about toxic substances getting into your living rooms. And, of course, ceramics are durable.

But there are also disadvantages. Ceramic pipes have high moisture absorption. If you choose them, you will have to provide good external ventilation and equip the structure with condensate drains, otherwise the invested effort and money will not be worth it.

Ceramic alone is not used in chimneys. To make the most of its positive properties, it is combined with mineral wool and stone. Simply put, the ceramic pipe is wrapped in insulating material and then placed in an expanded clay concrete shell.

Coaxial ventilation structure

When designing ventilation for gas boilers, pay attention to the compact “pipe-in-pipe” design, or, in other words, a coaxial chimney.

Coaxial systems, due to their characteristics, are suitable for heat generators with a closed combustion chamber (which is a gas boiler). Oxygen necessary for combustion enters through the outer pipe, and exhaust gases are removed through the inner pipe. This design has its advantages:

safety (exhaust gases are cooled by cold air circulating in the outer pipe);
the incoming air heats up and increases the efficiency of the boiler;
high efficiency means that the coaxial design is more environmentally friendly than others;
can be used with the appliance in the kitchen (it is located outside the room and does not affect the comfort in it).

Features of installing a coaxial chimney

You cannot use a horizontal coaxial chimney if you do not plan to install forced draft;
try to get by with no more than two knees;
if there are several boilers, create a separate chimney for each; combining them is undesirable.

Video - design and installation of a chimney and hood for a gas boiler

Natural and forced ventilation of the boiler room

According to the method of updating the air space, natural and artificial (or forced) ventilation are distinguished.

Natural ventilation operates without the use of fans; its effectiveness is determined solely by natural draft, and, consequently, weather conditions. The draft force is influenced by two aspects: the height of the exhaust column and the temperature difference between the room and the street. In this case, the air temperature outside must be lower than that indoors. If this condition is not met, reverse draft occurs and ventilation of the boiler room is not ensured.

Forced ventilation involves the installation of additional exhaust fans.

Usually these types are combined into one boiler room exhaust system. When calculating it, it is important to take into account that the volume of air drawn outside must be equal to that pumped into the room. To ensure this condition is met, check valves are installed.

Calculation of the ventilation system

According to building standards, the entire air space of the boiler room must be replaced with new one every 20 minutes. To ensure the appropriate air circulation, you will have to arm yourself with a calculator and formulas.

If the ceilings are located at a height of 6 meters, then without special devices the air in the room is renewed three times per hour. Six-meter ceilings are a luxury for a private home. The reduction in ceilings is compensated for in calculations in the following proportion - for each meter lower, air exchange increases by 25%.

Suppose there is a boiler room with dimensions: length - 3 m, width - 4 m, height - 3.5 m. To solve this problem, you need to perform a number of actions.

Step 1. Find out the volume of air space. We use the formula v = b * l * h, where b is the width, l is the length, h is the height of the ceiling. In our example, the volume will be 3 m * 4 m * 3.5 m = 42 m 3.

Step 2. Let's make an adjustment for the low ceiling using the formula: k = (6 - h) * 0.25 + 3, where h is the height of the room. In our boiler room the correction turned out to be: (6 m – 3.5 m) * 0.25 + 3 ≈ 3.6.

Step 3. Calculate the air exchange provided by natural ventilation. Formula: V = k * v, where v is the volume of air in the room, k is the correction for lowering the ceiling height. We got a volume equal to 151.2 m3 (3.6 * 42 m3 = 151.2 m3).

Step 4. It remains to obtain the cross-sectional area of the exhaust pipe: S = V / (w * t), where V is the air exchange calculated above, w is the air flow speed (in these calculations taken as 1 m/s) and t is the time in seconds. We get: 151.2 m3 / (1 m/s * 3600 s) = 0.042 m2 = 4.2 cm2.

The dimensions of the channel also depend on the area of the internal surface of the boiler. This number is indicated by the manufacturer in the technical documentation of the device. If this number is not indicated, calculate it yourself based on the volume of the device. Then compare the area with the radius of the section according to the inequality:

2πR*L > S, where

R – internal radius of the chimney pipe section,

L – its length,

S is the area of the internal surface of the boiler.

If for some reason such a calculation is difficult, you can use the table.

The last stage of the calculation is the height of the weather vane relative to the roof ridge. The need for this is due to the creation of additional draft by the wind, which increases the efficiency of the entire exhaust structure. At this stage, we are guided by the following principles:

the height of the weather vane above a flat roof, or at a distance of up to 1.5 meters from its ridge, must be at least 0.5 meters;
at a distance from 1.5 to 3 meters - not lower than the ridge of the roof;
at a distance of more than 3 meters - not lower than a conventional line drawn from the roof ridge at an angle of 10˚;
the weather vane should be 0.5 meters higher than the building, which is attached to the heated room;
if the roof is made of flammable materials, the chimney must be raised 1-1.5 meters above the roof ridge.

Installation of natural ventilation

Natural ventilation in the boiler room is ensured by installing supply and exhaust ducts.

To install the supply channel you need:

Select a piece of plastic pipe, a suitable size grille and a check valve. The diameter of the first is selected taking into account the power of the boiler. If the power is less than 30 kW, 15 cm is enough. Higher power means larger diameter.
To allow air to pass directly into the firebox, a through hole to the street is punched next to the heating device and not higher than its working area. Then a pipe is placed in the hole, the gaps inside are filled with mortar or foam.
From the outside, the hole is covered with a fine grille to protect it from dirt and animals. It is necessary to install a check valve from the inside to prevent backdraft to the street.

The exhaust duct is ducted outside through an opening above the boiler at the top of the room. Usually it is also equipped with a check valve that prevents air from entering from the street. The chimney can also be equipped with a protective rain canopy or weather vane, condensate drains and inspection windows for cleaning.

Artificial ventilation

Additional draft in the exhaust system is created using fans. Their power and number depend on the air load on the channel and the volume of the room.

power is taken from the calculation: maximum load plus a reserve of 25-30%:

max * 1.25, where max is the maximum load;

the number of devices is selected in proportion to the volume of air required for pumping (increase the volume of the room three times):

(h + b + l) * 3, where h – ceiling height, b – width, l – length;

the length of the chimney, its geometry and the number of bends are taken into account.

The fan is protected by an installation box. This box is made of non-flammable and stainless materials. Usually copper or aluminum alloys are used.

The design of artificial ventilation is similar to the installation of natural ventilation. After installing the supply pipe, the duct fan is installed. Next, the builders lay the wiring to power the engine, install sensors, a noise absorber and a filter. Just as when installing natural ventilation, grilles are attached to both ends of the pipe. The device for the exhaust pipe is installed in the same way, only taking into account that the air is drawn out and not pumped.

Artificial ventilation requires constant energy costs. Sometimes during construction they save money by installing a fan only for exhaust or only for air supply. However, more efficient circulation is achieved by using both.

The automatic ventilation system allows you to turn off the fans when the boiler is stopped and turn them on when it starts.

To install a chimney under a gas boiler, you must adhere to certain norms and rules. High-quality installation work contributes to more efficient heating of a private home. The shortcomings contribute to insufficient removal of combustion products, minimal draft, and increased costs. Reinstallation is expensive and economically ineffective, so it is necessary to clearly decide on the choice of equipment at the project development stage. Note that different types of structures have some subtleties during installation and are adapted to different temperatures of fuel combustion.

Among the general norms are the following:

Having chosen a heating system, taking into account the type of fuel, rated power, taking into account the requirements of the manufacturer, passport data, you should determine the cross-sectional area, the number of channels. An insufficiently large diameter will contribute to frequent attenuation and reduced draft, which will negatively affect the performance of heating equipment.

Insufficient diameter of the ventilation duct is the main cause of device malfunctions.

When constructing a chimney, you need to take into account some recommendations from experts: place the structure significantly higher than the ridge of the roof; with a flat roof, the chimney itself should be located at a distance of up to 3 meters. Massive structures require additional fastening.

Features of manufacturing materials

Considering the chimney for a gas boiler made of stainless steel, we will highlight the high characteristics of fire safety and tightness. The smooth surface and round cross-section contribute to the formation of good traction. When planning to install chimneys for gas boilers with your own hands, when buying pipes, you need to pay attention to the markings and the quality of welding of joints.

Focusing on brickwork, we note that exposure to condensation will have a negative impact on the integrity of the structure, which will not last long. Stains and mold will periodically appear on the walls and ceiling due to dampness.

A modern solution is to use furanflex, a material consisting of reinforced fibers and durable plastic. It has low thermal conductivity and is resistant to high temperatures. The use of galvanized pipes is fraught with the appearance of corrosion processes, so you should not count on a long service life. An attractive option is asbestos chimneys for gas boilers, the price of which is more affordable.

But there are a number of disadvantages:

complex installation process;
insufficient sealing of butt joints;
if overheated, the pipe will split or rupture.

Coaxial boilers

The presence of a closed combustion chamber is a distinctive feature of the use of coaxial equipment, therefore a gas coaxial boiler has a convenient smoke removal system. In turn, there are: wall-mounted (simple installation, convenient operation) and floor-standing boilers. There is a fairly simple principle of operation, when combustion products exit through the central hole of the pipe, while at the same time atmospheric air is taken in.

Modern flueless gas boilers are an excellent solution when installed in an apartment, since not all housing can be equipped with appropriate smoke exhaust equipment. For optimal operation, care should be taken to ensure sufficient ventilation.

For most consumers, the correct solution is when a coaxial pipe for a gas boiler acts as a chimney, the internal part is the chimney itself, fresh air enters the combustion chamber due to the gap between the pipes. A notable parameter is the simplicity of the device. The direction of the pipe can be: horizontal, upward, at an angle. In a horizontal position, equipment with forced ventilation must be installed, which helps remove carbon monoxide. Vertical installation is acceptable if the pipe does not interfere with neighboring apartments.

A modern coaxial pipe for a gas boiler, the price of which is acceptable for public sector housing owners, is a real solution for autonomous heating.

Advantages and disadvantages of chimneys made of various materials

As discussed above, the most common materials for the manufacture of smoke exhaust structures are brick, plastic, steel (you can study in more detail). Thus, chimneys for floor-standing gas boilers have distinctive features and advantages, depending on the material of manufacture: ceramic products eliminated the disadvantages of brick structures.

However, many owners of private housing prefer to save money and buy a chimney for a gas boiler at a more reasonable price, regardless of the performance characteristics. Steel structures are also not the best option due to the effects of corrosion and significant temperature differences. If there is no operation for a long time, ice will form on the inside of the pipe.

The sandwich chimney combines lightness of design, versatility of installation, resistance to corrosion, has a worthy competitive position, and is widely in demand on the market.

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D To remove combustion products inside the furnaces of heating devices, chimneys for a gas boiler in a private house of different designs from different materials are used. The standards SP 7.13130 specify the requirements for cross-sections, heights, location of chimneys, safe diagrams of passage units through structures made of flammable materials.

Chimney from a gas boiler on the facade of the house

Requirements for chimneys and installation rules

Combustion products have high temperatures, so chimneys must fully comply with the standards of SP 7.13130. The use of factory products that have not passed the Russian Federation certification is not allowed.

The main provisions of the set of fire safety rules are:

internal cross-section of the chimney - 14 x 14 cm - 14 x 27 cm depending on the thermal power of the boiler (3.5 - 7 kW, respectively) for concrete, brick, ceramic structures, the area of round or asbestos-cement pipes must correspond to these dimensions;
height – 5 m minimum from the firebox to the deflector;
chimney thickness - 6 cm for heat-resistant concrete, 12 cm for ceramic brick, not standardized for asbestos cement, sandwich.

The height of the deflector (an umbrella structure that protects the pipe from rain and wind) relative to the ridge depends on the distance of the chimney from it:

0.5 m higher at a distance within 1.5 m;
level with the ridge at a distance of 1.5 - 3 m;
at the level of an imaginary line at an angle of 10 degrees relative to the horizontal, drawn from the ridge to the pipe, at a distance of more than 3 m from it.

When moving the chimney outside, elbows are allowed within 1 m from the axis of the main pipe to the side at an angle of less than 30 degrees relative to the vertical. The cuts should exceed the thickness of the floors with decorative ceiling cladding by 7 cm with an even distribution of this size from below/top.

The distances from the outer surfaces of structures to wooden elements of load-bearing structures (sheathing, rafters, beams, crossbars) must be greater than the specified dimensions, depending on the chimney material:

Attention! It is prohibited to combine chimneys with ventilation ducts without a special design. But you can run combustion products from two boilers into one pipe if necessary.

Chimney structures

When choosing a chimney or channel, you should focus on the best combination of construction budget, resource, and maintainability. Depending on the materials used, chimneys for a gas boiler in a private house are attached with clamps to the enclosing structures or rest on separate foundations.

In all vertical structures, a serious problem is the formation of condensation, which is released when hot gases come into contact with the cold walls of the pipes. In coaxial modifications, which are often located horizontally, this disadvantage is absent. In addition, it is enough to give the pipe a slight slope towards the ground so that possible condensation drains out of it without additional costs.

Sandwich installation

Chimneys made of two pipes of different diameters, inserted into one another, with a heat insulator between them, are called sandwiches. The design allows you to reduce the external temperature of the walls (increased fire safety), eliminate the formation of condensation (useful for increasing the service life).

A sandwich chimney of a wall-mounted gas boiler is installed in a private house using two technologies:

Attention! Gas boilers have gases with low temperatures at the exit from the combustion chamber. Therefore, the “condensate” technology is used.

The chimney assembly technology looks like this:

installing a damper on the boiler outlet pipe to adjust the cross-section of the chimney channel;
installation of pipes until they are blocked by condensate;
making a cutting from a steel box attached to the floor from below;
cutting through the chimney, building up to the roof;

fastening to the canopy sheathing - a plate with a conical pipe located at the desired angle to it, depending on the slope of the slopes;
fixing the sandwich chimney pipe to the roof with a okapnik (a conical clamp of a complex profile), which decorates and seals the joint.

After that, it remains to install one of the elements at the mouth of the pipe:

volper - deflector for increasing traction with a flat lid;
weather vane - deflector to improve draft of the original design;

fungus – conical nozzle for protection from precipitation.

These elements are made of stainless steel and fully correspond to the style of sandwich chimneys.

Stone and brickwork

Chimneys for a private house can be built into brickwork (only into a load-bearing internal wall) or made from blocks. Domestic manufacturers produce several types of chimney modules:

concrete - used only in conjunction with ceramic pipes running inside them, the outer surface is square, the inner is round;

ceramics - pressed into special molds, then fired in kilns, have the design of an internal pipe, an external square thin-walled box, connected by stiffening ribs.

The Ukrainian company Schiedel produces chimney blocks made of volcanic pumice. The modules are called Isokern and are a budget option for individual developers. The material is much lighter than concrete and ceramics, the only drawback is the rough inner surface and the lack of Russian certificates. Regional fire safety services accept structures made from this material in 50% of cases.

Brick chimneys are built into walls during the construction of enclosing structures. To lay the blocks, it is necessary to concrete a separate foundation. But, the pipes can be placed in any convenient place, there are no problems with the passage units, rafter systems, or floors.

Asbestos cement pipe

Aggressive advertising by manufacturers of sandwich chimneys cites the main disadvantage of asbestos - the lack of environmental safety. In fact, only safe raw materials and technologies are used in domestic production. According to reviews from craftsmen who install all types of modern chimneys, an asbestos-cement pipe has the following advantages:

is self-supporting - no need to attach to walls;
does not condense moisture - there are no leaks into the combustion chamber;
resistant to combustion products - the resource is higher than that of concrete and brick;
cheaper than ceramics - the cost is much lower.

Installation of an asbestos cement pipe is extremely simple:

the first pipe is installed on the foundation, secured with racks or a frame;
the chimney is increased to the required height, the pipes are connected with couplings;
The top is covered with a deflector, and a hatch is made at the bottom to install the cleaning door.

The connection from the boiler is made with a steel elbow, which can be replaced if necessary.

Installation of coaxial structure

Unlike other chimney modifications, a coaxial pipe can only be used for closed combustion chambers. (supercharging) is a mandatory operating condition of the system. The design of a coaxial chimney is similar to a sandwich, but instead of insulation, there are jumpers between pipes of different diameters. The inner pipe is used to remove combustion products; the street air necessary for burning natural gas is sucked into the interpipe space.

Unlike conventional chimneys, the pipe does not need to be pulled vertically across all floors. Instead, a 90-degree outlet is put on the outlet pipe, a coaxial chimney is attached to it horizontally, and goes out through the nearest wall while maintaining fire safety distances:

maximum length of horizontal part 3 m;
minimum 0.2 m to the ceiling, floor, ground;
more than 30 cm from the axis of the chimney to the wall surface;
at least 60 cm from the mouth of the pipe to the opposite wall.

The coaxial structure can be installed vertically above the roof, horizontally through the wall, or connected to a smoke duct built into the brickwork of the wall.

conclusions

Thus, for closed combustion chambers, a coaxial chimney is preferable, saving the construction budget and the aesthetics of the roof, in which there will be no holes. The most reliable for open fireboxes are asbestos-cement pipes or sandwiches. The most discreet wiring is ensured by built-in smoke channels in brickwork, structures made of concrete, ceramic blocks or Isokern modules made of volcanic pumice.

The arrangement of the exit path for carbon monoxide from the boiler must be carried out in accordance with established requirements and standards. There are dimensional and other restrictions for the chimney so that the outflow of smoke from the gas boiler is carried out safely for human health.

Each individual heating system has its own special requirements for organizing a combustion product removal system. For gas heating equipment, the main thing is to design the chimney in such a way as to ensure the best possible draft.

Gas boiler with chimney and air intake pipe

Ill-proper chimney system equipment can lead to the penetration of carbon monoxide into a living space - this, in turn, poses a serious danger to human health and life.

Requirements for the material for the manufacture of chimneys

The following requirements apply to the material used for the manufacture of pipes intended for the removal of flue gases:

resistance to high temperatures;
high anti-corrosion qualities;
chemical inertness.

Exhaust pipe

Inside, on the walls of the smoke exhaust pipes, due to constant temperature changes, condensate constantly forms, which contains a high content of sulfuric acid. Therefore, it is extremely important that the material used to make the chimney does not react chemically with acids and also has excellent corrosion resistance. When purchasing, you should also separately specify that the thickness of the inner layer is at least 0.05 cm.

Advice. To reduce the amount of condensate released inside the pipe, the chimney should be insulated.

Metal, ceramic or coaxial chimney?

In a private house, chimney pipes for gas-fired boilers can be metal, ceramic or coaxial. The preferred type of flue pipe material that is suitable for use with a particular boiler is usually indicated by the manufacturer in the technical documentation.

Chimney device

The most common option is a metal chimney that can withstand an operating temperature of 800 degrees. Typically, the pipes of such chimney structures are made of stainless steel; ferrous metal coated with zinc can also be used as a manufacturing material.

In general, the standard design consists of several components: the inner layer of the chimney is made of stainless steel, on top of which there is a layer of heat-resistant basalt wool and a thin iron casing. Among the advantages of metal chimneys are high resistance to mechanical damage, as well as increased reliability and a universal, presentable appearance.

Ceramic chimney pipe

Ceramics, which can withstand up to 1200 degrees, are in slightly less demand among consumers. The structure also consists of three layers: a ceramic component, a layer of insulation and a hard shell of expanded clay concrete. Chimneys made from this material are distinguished by their simplicity and reliability, ease of installation, as well as high fire safety.

The coaxial chimney is valued for its presentable appearance and fairly high performance characteristics. In general, this type of construction has a somewhat specific shape, due to which it has an important advantage - condensation does not form on its internal walls. This property is very important for gas equipment, so when choosing a suitable material you should consider purchasing a coaxial chimney.

Diagram: coaxial chimney device

Attention! Brick pipes are suitable for solid fuel, not gas equipment. Therefore, for gas boilers, an old brick chimney must be converted by inserting a liner made of metal, followed by insulation.

Basic standards

Section size and shape

When calculating the cross-sectional area of a chimney pipe, the dimensions of the pipe installed on a particular gas boiler are taken into account - the chimney ultimately must be no smaller in size. Two boilers can be connected to the chimney pipe, but only on the condition that their inputs will be located at different levels and at a distance of 0.5 m relative to each other.

In this case, the cross-sectional area of the pipe is calculated as the total power of both heaters, multiplied by 5.5. For example, provided that the power of one according to the passport is 1 kW, and the other is 1.4, the cross-sectional area of the common pipe will be (1 + 1.4) x 5.5 = 13.2 cm square.

Installation of a chimney system for a gas boiler

The cross-sectional shape can be in the form of a rectangle or a circle. The smoke flow moves in a spiral inside the chimney pipe and, encountering corners, loses its speed, therefore the round shape is more preferable, allowing for high-quality draft.

Pipe location

The chimney must be installed in a vertical position. The permissible deviation is no more than 30 degrees or up to 1 meter in any direction. At the point of connection to the chimney pipe of the gas unit, a vertical section must be installed, and the height of the section must be at least 0.5 m.

Correctly installed chimney for a gas boiler

Ideally, there should be no bends and all kinds of roundings on the chimney pipe at all, but up to 3 such outlets are allowed. It is allowed to slope horizontal pipes exclusively in the direction where the boiler is located, with a slope angle of up to 0.01 degrees.

Number of probes

It is allowed not to install headers if they impede the exit of flue gases. Under each of the probes, which are located on the tip, you cannot place more than 1 pipe, that is, all individual pipes must have their own “fungi”. The headband must have a cone shape.

Rules for the installation of chimney pipes intended for gas units

During the installation process, you must adhere to a number of established rules:

installation is always carried out in the direction from bottom to top;
the structure is attached strictly vertically;
pipes in height should not reach more than 5 m;
the slightest deflections of pipes are excluded;
all joints, transitions and curves must be carefully sealed using heat-resistant sealant;
along the path of smoke movement there should not be more than 3 horizontal transitions more than 1 meter long;
the head should be located above the wind pressure zone.

Chimney outlet options

Another important requirement for a chimney structure is the mandatory fastening of the pipe to the adjacent wall. Ideally even sections of the pipe are fastened in sections of 150 cm, while its individual parts are fixed to each other without exception. To enhance the overall reliability of the structure, all connections of the elements are fastened together with metal clamps.

SNiP requirements

Regardless of the type of construction, all chimneys for gas boilers must be manufactured and installed in accordance with SNiP 2.04.05-91 and DBN V.2.5-20-2001. Strict adherence to all requirements guarantees safe operation of the heating system. If the standards set out in these documents are violated, problems will arise that will need to be resolved directly with the gas industry.

Proper chimney installation

The main points of the regulatory documents:

good traction must be organized;
the design of the condensate collector must be carefully thought out so that excess moisture does not accumulate on the walls of the chimneys;
It is not allowed to install fungi, deflectors, etc. on the chimney head, since they slow down the process of removing combustion products;
When carrying out installation work, special attention must be paid to the tight fit of all individual structural parts at the connection points;
A mandatory requirement is to maintain complete tightness at the joints and joints.

Conclusion

The installation of chimney pipes is a responsible process. If installation errors are made, the system may fail, causing serious harm to health and even a threat to human life. Also, if the requirements and standards are not met, more frequent cleaning of the pipe will be required, since large quantities of ash will settle on its walls.

Connected gas boiler

Therefore, during the installation process, especially when it comes to a complex chimney system, it is recommended to involve qualified specialists who will draw up a separate project, as well as carry out all the necessary calculations and ensure the uninterrupted functioning of gas equipment.

Connecting a gas boiler: video

Chimney for a gas boiler: photo

One of the most important parts of a solid fuel boiler is the chimney. Through it, flue gases and soot are released into the atmosphere. It ensures high boiler operating efficiency and high efficiency.

Intensive use of the chimney pipe leads to clogging. The cross section decreases, combustion products cannot pass through quickly. As a result, traction decreases, the device begins to work in heavy duty, and efficiency decreases.

To prevent soot accumulation and for the boiler to function normally, the chimney pipe must be made from appropriate materials according to well-executed drawings. In addition, it is very important to correctly calculate the diameter and cross-section.

When the system has insufficient thrust, poor fuel burn occurs. As a result, soot is formed. It gradually clogs the pipe passage, reducing its cross-section.

You can, of course, achieve increased draft by increasing the cross-section of the chimney pipe. But this will not lead to a positive result. The heat from the boiler will simply leave the room through the pipe. To be able to regulate the draft, the boiler is equipped with special dampers.

The appearance of draft is based on the difference in temperature between the room and the environment. The draft becomes maximum when the cold weather sets in. A small temperature difference is enough so that combustion products do not settle on the surface of the pipe, but escape into the atmosphere. This can happen under one condition. The chimney must be properly designed and installed.

When the boiler starts working, outside air is supplied to the combustion chamber. Due to this, the combustion process is supported. Exhaust gases are directed into the chimney and quickly thrown out.

If the pipe diameter is insufficient, exhaust gases begin to accumulate inside the combustion chamber. As a result, the fire begins to fade, and there is heavy smoke in the room.

The traction force depends on several factors:

Pipe length.
The presence of turns.
Bends.

For example, the presence of a right angle in a structure greatly reduces its maneuverability. This becomes noticeable when the atmospheric pressure decreases. To correct this situation, a special stabilizer is installed in the rod.

Additional features of the chimney

It should not react to high temperatures. Therefore, a chimney made of particularly heat-resistant materials is installed in a solid fuel boiler. When coal or wood burns in such a boiler, the temperature of the smoke is much higher than the temperature of gas combustion. For example, the smoke temperature of a gas boiler does not exceed 200 degrees. When wood burns, the temperature can exceed 300 degrees. If the boiler is heated with coal, the temperature reaches 600 degrees. Sometimes there is a temperature jump. It begins to rise when heated.

It is prohibited to ignite the combustion chamber with solid fuel, gasoline, or other flammable substances. This option can cause a soot fire due to a burnt-out chimney. It is strictly forbidden to try to remove contaminants in this way.

Chemical neutrality

When a boiler uses solid fuel for operation, materials that are neutral to the effects of chemical elements must be used. Do not forget that the resulting condensate contains a large amount of sulfuric acid. That is why the chimney material should not be afraid of an aggressive acidic environment

Reliability

This requirement remains very important for the operation of the boiler and traction. However, many are stopped by the price; they simply forget about safety. Of course, it is much easier to replace a completely broken chimney. But if there is no draft, the room will begin to fill with carbon monoxide. It has no odor, so you can simply fall asleep in the room and never wake up again.

How to calculate chimney sections

When choosing, you need to first measure the existing cross-section of the pipe. It should have the same dimensions. It is desirable that the sizes match. If the diameter is larger, a drop in pressure will occur and the traction force will decrease.

It is prohibited to operate two solid fuel boilers with one chimney. Each must be equipped with a separate pipe. With the correct selection of diameter, as well as competent installation, there will always be good traction.

The cross-sectional size (sq. m) is determined by the formula:

volume of fuel consumed (m3/s) / gas velocity.

The chimney can have different cross-sectional shapes:

Circle.
Rectangle.

For normal operation, you can use any option, but a round section is still much preferable. When smoke moves inside the pipe, it spirals. Any foreign part in the pipe creates resistance to the movement of the gas flow.

If the inner surface of the pipe is rough, the gas velocity will decrease. When smoke, during circular movements, collides with a right angle, a sharp change in trajectory occurs, and mixing occurs. As a result, soot settles in the corners.

Constant, thorough cleaning will be required.

What materials should exhaust pipes be made of?

With a wide variety of materials, only a few types can be used to operate a chimney. The main ones are:

Brick.
Metal.
Ceramics.

The most popular are pipes made of brick. They are able to withstand very high temperatures. Its maximum reaches 1000 degrees. Today, on the roof of modern expensive cottages you can see an original chimney made of eurobrick. However, upon closer examination, you can see pipes inserted inside the brick chimney. They can be steel or made of ceramic. This is explained very simply. One brick is not suitable for normal operation. In other words, it will work, but not for very long. It will quickly be destroyed by caustic condensation. Therefore, a liner is inserted into the brick pipe. Free cavities are filled with insulating material.

Sandwich pipes made of ceramics can withstand very high temperatures. It can exceed 1200 degrees. This value is much higher than the maximum smoke temperature after coal combustion.

Such a pipe is not afraid of condensation and any atmospheric phenomena. Condensate is drained through a special drain hole. Sometimes for this purpose an additional container is made at the end of the watering can. A ceramic chimney pipe is installed on the facade or inside the building.

A chimney of the Schiedel Uni brand, if a soot fire occurs, is able to cope with such a thermal load. When burning, soot heats up to a temperature of 1100 - 1200 degrees.

Disadvantages of ceramics

They do not have a beautiful appearance. Their cost is much higher than their steel counterparts. Installing these pipes requires construction skills and experience. These pipes remain popular among consumers with low incomes.

Metal chimney

For its manufacture, ordinary steel or stainless steel is used. Unfortunately, steel chimneys cannot withstand

aggressive environment. When the boiler operates continuously, the pipe will become unusable in a very short time and may cause a fire.

The composition of the stainless steel used includes special additives consisting of several chemical elements

Titanium.
Nickel.
Molybdenum.

They are the ones who save stainless steel from corrosion. For installation

The following steel grades are used in boilers:

316 L.

They contain substances that allow steel to withstand temperatures between 700 and 800 degrees. These grades of steel are not afraid of condensation, they are neutral to acids, and do not react with other aggressive substances.

The cost of a chimney made of stainless steel is affordable to the average buyer. It is considered most suitable for installation in a solid fuel boiler.

Glass chimney

Very rare. Its positive qualities include:

Low thermal inertia.
Corrosion never occurs.
Original look.

The cost of such a design is very high. Therefore it is very rare. In addition, its installation is very labor-intensive and costs a lot of money.

Device and installation

When installing a metal chimney, work starts from the bottom, gradually moving upward. Pipes can be connected in several ways:

By the movement of smoke.
For condensate

When the boiler is connected to the chimney according to the first option, installation occurs from the boiler. The second option, on the contrary, goes to the boiler. The metal structure consists of several parts:

Cup.
Pipe sandwich.
Condensate collector.
Spark arrestor.
Header.
Cleaner.

To create a reliable connection, establish:

Adapters.
Tees.

The joints are fastened with clamps from the outside.

Technological requirements

The following technical requirements must be observed:

A special area must be provided to disperse the smoke. It is a vertical pipe installed behind the nozzle of a solid fuel boiler. The acceleration section is made one meter high.
The chimney is installed only vertically. Deviation of no more than 30 degrees is allowed.
Deflections are prohibited.
The length is very important (3 - 6 meters).
Three horizontal sections are allowed. Moreover, the length of each should not exceed half a meter.
The height of the head above the roof must exceed 100 cm.
The pipe is attached to the wall in 1.5 meter increments.
To create a sealed joint, the pipes are generously lubricated with heat-resistant sealant.

To obtain ideal draft, it is necessary that the chimney design has a minimum number of turns. A straight pipe is considered best.

The chimney can be installed inside or outside the building. For the first option, it is necessary to protect the pipe so that it does not come into contact with flammable materials. A special metal screen is used, installed where the pipe passes through the ceiling. The chimney must be located at a distance of more than 25 cm from the wall.

External structures look much safer. They are much easier to maintain. Masters consider this method the most preferable.

Pipe height

This size is determined by SNiP, which sets certain parameters:

If the roof is flat, the chimney should rise 1.2 meters above it.
If the chimney is located near the ridge, and the distance is less than 1.5 meters, it should rise above the ridge by 0.5 meters or more.
When the pipe is located in the range of 1.5 - 3 meters to the ridge, it should not be below the ridge line.
If the location of the chimney from the ridge exceeds 3 meters, its height should be on a line extending from the ridge, maintaining an angle of 10 degrees relative to the horizon line.

To determine the height of the chimney, a large number of indicators are taken into account. The parameters presented above apply only to gas equipment. To make an accurate calculation, you need to use the services of a specialized company.

Fire safety technology

It is allowed to install a chimney in accordance with the requirements:

SNiP 2.04.05–91U.

DBN B 2.5-20–200.

NAPB A.01.001–2004.

Installation should only be carried out by professionals. The cross-section of the chimney must correspond to the value specified by the manufacturer in the instructions supplied with the boiler.

If there is a horizontal section, its length should not exceed one meter.

The design must provide for the possibility of draining condensate, as well as cleaning the smoke exhaust channel.

How to connect a chimney

All connections of parts to the nozzle of a solid fuel boiler are made with a heat-resistant sealant that can withstand temperatures in the range of 1250-1500 degrees.

When the diameter of the chimney does not match the size of the chimney outlet, an adapter is installed to create a tight joint.

How the parts are assembled

Any single-walled, as well as sandwich, with insulation, are assembled in only one option: “pipe is inserted into pipe.” The connection points of the chimney parts do not require the installation of additional clamps.

If the structure is made of special stainless steel, assembly is carried out only using condensate. In this case, condensate, as well as the resulting tar deposits, will never get out; they will flow along the walls of the pipe directly into the condensate drain.

If an inspection is used in the chimney and tees are installed, all parts are assembled “in the smoke.” The assembly of vertical parts extending from the tee is carried out “using condensate”.

If it is necessary to line the channel, the gap formed between the pipe and the channel must be more than 4 cm. It is necessary when the metal expands when heated.

To ensure that the chimney sandwich parts have a more rigid fastening, rivets are installed or screws are screwed in.

Fixing the chimney

The pipe is attached to the wall only with special materials.

The single-wall structure must be fastened with a fastening step of 1.5 meters on all vertical sections of the pipe.

If the sandwich chimney does not have a supporting structure, it is necessary to secure each element.

If the system uses a 45–87 degree tee or a 45–90 degree elbow, installation is carried out in such a way that the load on the rotating parts of these parts is completely eliminated.

If installation requires additional support, use a floor stand installed under the inspection.

When the chimney pipe is raised above the roof by more than 1.5 meters, a bracket must be installed under the brace.

Passage through floors

To make a passage through the wall of a house or its ceiling, it is necessary to use the building codes that are in force today in Ukraine.

If a sandwich chimney with insulation passes through wooden walls, a liner must be installed and another layer of thermal insulation is applied.

When a chimney pipe is installed through the roof, builders must install a special additional pipe part, the so-called “roof”. Another additional layer is created, consisting of fireproof insulating materials.

The final stage of construction

When a brick chimney is lined, its upper part is closed with an additional part - the end.

Usually the top of the pipe is covered with a baffle or a beautiful fungus.

If the building's roof covering is made of a fire-hazardous material, such as bitumen shingles, a special spark arrester is installed on the top of the chimney.

If a gas boiler is installed in the house, installing a deflector is strictly prohibited. According to current regulations, the upper part of the gas device pipe is always kept open.

Starting the chimney

Check again that there are no flammable or flammable objects near the chimney to prevent a fire.

The protective film is removed from the parts.

The gate that regulates the traction force opens.