In order to make the correct chimney device, you must have a detailed diagram of this structure. Incorrect laying can provoke the accumulation of harmful toxic substances inside the room. Such work should be carried out by a highly qualified specialist who knows everything about such a structure.

The correct level of smoke draft ensures that carbon monoxide gases are quickly transported out of the living space. Such a structure is a kind of pencil case that removes corrosive combustion products.

Several chimney models are presented in specialized departments. They differ in their structure and the material from which they are made. Our guide provides detailed instructions on how to make a do-it-yourself chimney for a stove. Experienced specialists' recommendations make this task much easier.

Chimney types

Diversion shafts through which harmful gases saturated with combustion products are removed are required not only for standard stoves, but also for fireplaces and gas boilers. Today, several types of chimneys are known. These include:

Straight streaming. This variety is considered a popular structure, which is most often used for arranging living space. The only drawback of such a chimney is its rapid heat loss. In addition to toxic substances, most of the heat energy evaporates here.

Straight flow pipes with bridges. They trap most of the heat during the combustion of materials. This design is often used in baths. Such a long burning chimney for a stove requires constant cleaning. Ash quickly settles on the surface of the bridges, thereby preventing the rapid elimination of toxic substances.

Straight streaming chimney with a labyrinth. This variety has a high heat dissipation. Carbon monoxide gases pass through numerous bridges. They quickly heat up the walls of the chimney, thereby contributing to the maximum heating of the room.

Bell-type. It is used for the Russian stove. The hot smoke rises quickly, where it gradually begins to cool. After that, it descends along the arch of the chimney masonry. The only drawback of such a structure is its uneven heating.

Modular. They are made from a metal alloy. They are intended for gas-fired heating systems. Metal chimneys for stoves are able to cope with the acidic compounds of methane combustion products. Brickwork in this case will quickly collapse.

Chimney device

The efficient operation of a chimney shaft directly depends on several criteria. For example, the section, height and material from which it is made.

What must be considered in the process of a device of such a design:

The size of the outlet of the heating device should be slightly smaller than the cross-section of the flue duct. If the diameter is slightly larger, then an additional adapter will be needed, which will regulate the process of removing smoke.

Particular attention must be paid to the horizontal part of the structure. Warm air moves up quickly. Soot and combustion products quickly begin to settle here.

Traction control will help shorten this process by reducing the length of these segments. They should be less than one meter. In addition, it is necessary to provide a condensate receiver and doors for cleaning the chimney.

For a sauna stove, it is best to use a vertical chimney. In some cases, a metal pipe can be laid. It is recommended to observe the correct angle of inclination during the fixing process. It should be no more than 2 meters.

Stages of creating a vertical chimney

To create a chimney shaft, you need to prepare the following tools and materials. For this you will need:

• first grade brick;
• construction composition;
• level;
• guide rope;
• stairs;
• design diagram.

Chimney creation includes the following steps:

The first layer is laid out with five bricks. The masonry should be neat and even. Subsequent rows are done in the same way.

When the required height is obtained, you can proceed to the construction of the edge. Each subsequent row lays down 35 ml more. The result will be a stepped structure in the area of \u200b\u200bthe ceiling.

After the pipe has reached the attic level, they begin to lay it according to the initial stage. The hole diameter should be gradually reduced.

The final stage will be the removal of the brick shaft outside the roof. The photo of the chimney for the stove shows the entire working process.

Photo of chimneys for the stove

Various materials are used for the manufacture of chimneys, some of which have been used for several centuries, while others have become actively used only a few years ago. Each type of smoke outlet has its own characteristics, so it is important to have an understanding of each of them.

Chimney materials

The considered structural element of the heating system can be built from traditional building materials, but wealthy owners can also afford materials created using the latest technologies. The choice of a solution for a specific home primarily depends on economic feasibility, fire safety requirements and the aesthetic views of the home owner. We advise you to study more information about in addition to this article.

Metal chimneys

As mentioned above, metal pipes for smoke removal are divided into single-layer and double-layer. Single-layer are a cylinder, which, as a rule, is installed inside a brick or ceramic chimney. Two-layer ones consist of two cylinders of different radii, between which a layer of heat-insulating material is placed, in the role of which is most often basalt mineral wool.

Advice! If your home has an antique exterior design, the metal chimney can be covered with a copper jacket to maintain stylistic consistency.

Black metal

High-quality chimneys made of this material are covered with a layer of enamel on top, which reduces their susceptibility to burnout and corrosion. As a result, such a product can last for a long time at temperatures up to 500 ° C, while short-term drops of up to 700 ° C are permissible.

The key advantage of ferrous metal smoke exhaust pipes is the lowest price, but their performance does not allow them to be an effective solution for stove heating operating in intensive mode.

Stainless steel

This material is ideal for any type of chimney. Alloy stainless steel withstands temperatures well up to 850 ° C and also withstands peaks up to 1200 ° C. We have already written about and recommended to bookmark the article.

The best brand for structures of this type is considered AISI 321 (the composition contains impurities of molybdenum), but AISI 316 and AISI 304 are also widely used. It should be noted that many unscrupulous manufacturers produce products from less heat-resistant brands, as a result of which they can burn out already through 10-15 years of light use.

Advice! When choosing a stainless steel chimney, be sure to ask about the quality of the steel. You can independently evaluate this parameter using a magnet: good steel has a large amount of alloying additions, as a result of which it does not magnet.

DIY chimney sandwich for the oven

The best option for installing a stove chimney with your own hands would be a stainless steel sandwich system. It looks good and meets all modern fire safety standards. An important advantage is the fact that it is as easy as possible to assemble it alone, without having experience and special knowledge. It is enough to adhere to the following recommendations:

• The installation process should start from the bottom elements.
• In places where the pipe contacts wood and other fire hazardous materials (in the area of \u200b\u200bthe attic or roof), insulation, for example, stone wool, must be used.
• In order to protect the surface of the ceiling in the area of \u200b\u200bthe chimney passage, a steel platform should be installed.
• In the case of creating an outer pipe, it is necessary to include tees in the system for condensate drainage.
• The above elements are inserted into the ones below.
• It is advisable to protect the upper outlet of the chimney with a thermofungus, weather vane, deflector or spark arrestor.

Homeowners, as a rule, take the organization of heating in their home very seriously, choose the safest boiler models, and turn to experienced stove-makers. However, it is sometimes overlooked that incorrect installation of the chimney is often even more dangerous.

The chimney is the most important element of the heating system in a private house, the assembly of which is carried out in accordance with building codes and fire safety requirements. The installation of a chimney, performed without observing these rules, is fraught with irreversible consequences - the occurrence of a fire or carbon monoxide poisoning in the house. Today's article will tell you about the types of chimneys, device and installation methods.

The chimney serves to carry smoke and combustion products into the atmosphere, it starts from the inlet of the heater in the house and ends above the roof ridge with a protective umbrella. In private construction, the following types are mainly used:

The material from which the chimney is made can be correctly selected based on three factors: compliance with the material of the heater, low thermal conductivity and tightness of the joints.

Chimney outlet methods

The main task of the chimney is to remove smoke outside the house, which can be organized in several ways. The choice of the pipe insertion location depends on the location of the heater, free area and the type of chimney. The following pipe placement options are used:

External placement is well suited for the bulky structure of a brick chimney, and if you bring a metal pipe through the wall, you will have to take care of additional insulation or the use of special sandwich pipes.

Chimney requirements

The selection of elements is carried out taking into account the requirements of the technical characteristics of the heater. For the system to work smoothly, the basic principles of chimney design must be observed:

1. A round shape is preferable, since combustion products and dust accumulate in the corners of the pipe. Round chimneys require less cleaning than rectangular and square ones.
2. The section of the pipe must not be less than the diameter of the pipe of the heater. It is calculated that for each kilowatt of power, 8 kW is required to ensure the proper level of thrust. see section. Usually, information on the required chimney size is contained in the instructions for the heater.
3. Each heater requires the installation of its own chimney. In some cases, you can deviate from this rule, but then the devices should be located at a different height, the distance between the connection points is 1 m or more. And the size of the pipe section must take into account the total power of the heat generators.
4. The total length of the horizontal sections of the chimney cannot exceed 1 m, violation of this rule reduces the draft force.
5. The chimney ends 0.5-1.5 m above the ridge, on a flat roof - 0.5 m above the surface.

The main criterion for the selection of pipes - fire safety requirements and compliance with a heat-generating device, appearance, aesthetics and economy of space inside the house are secondary.

Installation sequence

The installation of an internal chimney begins with drawing up a diagram and calculating the required number of pipe segments. To complete the assembly correctly, the device is performed in the following order:

Chimney outlet scheme through the roof from corrugated board

After the completion of the installation, it is necessary to start the heating systems, check the traction and tightness of the connections - even a slight small smoke indicates serious problems, the solution of which is unsafe to postpone.

Installing a chimney in a house is a responsible event, the quality of which determines the comfort and safety of the heating system, therefore, follow the recommendations of the manufacturers, the technology of installation work.

Video instruction

The technology of laying a brick chimney itself is quite simple and understandable, since, unlike the brick oven itself, the pipe usually does not have internal channels that are complex in configuration. However, despite the relative simplicity of the design, one cannot but take into account the colossal significance of this section of the furnace, since the quality of heating at home and the safety of both the structure itself and the people living in it directly depend on it. Therefore, in order for all the work to be crowned with success, it is necessary to approach it with the utmost care, relying on the recommendations of experienced craftsmen and on the developed and tested design schemes.

When erecting a chimney, it should be remembered that the evenness of the inner walls of the channel is no less important than the aesthetics of the outer masonry. This circumstance determines not only the stability of the required thrust in the furnace, but also the duration of operation of the chimney without cleaning, since the smoke rising through the pipe leaves on smooth walls, without protruding solution and deepened seams, a much smaller amount of fuel combustion waste, and the channel overgrows much slower.

What are the types of brick chimneys?

Chimneys of brick stoves can be of different types, depending on the place of their installation, the design of the stove, as well as on how many heating devices will be connected to the pipe. So, there are three main types of brick chimney pipes: they are packed-on, root and wall.

• Wall mounted chimneys ... The most widely used designs are casing pipes. They are good because they are compact and do not take up additional space in the room at all, but simply are a vertical continuation of the oven.

They are erected on top of the last brick row overlapping the furnace, around the hole left. Then the pipe is passed through the attic floor, attic, rafter system and rises above the roof.

• Indigenous chimneys ... This type of pipe is installed in cases where it is planned to connect a metal stove to it, or several heating devices located on one or even several floors.

In addition to metal, brick ovens can be connected to such a pipe. This type of chimney is especially convenient in the event that it is necessary to build two stoves in the house in adjacent rooms. For example, a kitchen needs a stove with a hob, and a neighboring room needs only a heating one. In order not to lay out a separate pipe for each of them, a main chimney is built between the rooms, to which both heating devices are connected. To a pipe of this type, not only two, but also three to four stoves can be connected, located on different floors of the house. In any case, it is necessary to very accurately calculate the size of the internal channel of the chimney, otherwise normal draft may not be ensured when several devices work simultaneously. The answer to the question, why can be different.

• Wall chimneys are built near the main (external or internal) walls or are built into them. They can be used, just like the indigenous ones, to connect several stoves located on different floors of a building.

The convenience of this design lies in the fact that it is located, as it were, outside living quarters, without occupying their area. For example, on the first floor of the house a fireplace can be built and connected to the wall chimney (there the chimney will look more like a top-mounted one according to the principle of structure), and on the second floor a chimney pipe of a metal stove is cut in (the same as in the version with a fundamental requirement).

The disadvantages of this chimney option are the considerable cost of the project and the laboriousness of the work. Firstly, much more building material is required to erect this structure. Secondly, the chimney, if it is partially on the street, requires serious insulation measures, otherwise in winter, with temperature drops, condensation will form in the internal ducts, which will significantly reduce the efficiency of the heater. Therefore, if this option of the chimney is chosen, then it would be more prudent to sacrifice the area inside the premises and bring the pipe along the inner wall of the house.

Parameters of brick chimneys

Main sections of a brick chimney

The brick chimney is subdivided into departments that have a different purpose and are named differently. These features must be clarified immediately, so that in the future it will be easier to understand the description of the work on the construction of the pipe.

1 - Pipe head. Laying out this part of the chimney, the bricks are shifted to the outside to form a kind of "visor", as if hanging over the lower sections, partially protecting the pipe walls from precipitation.

2 - The neck of the pipe is located immediately under the head and has the same perimeter along its entire height, without protrusions, extensions or narrowings.

3 - "Otter" has a more complex masonry scheme, since it has a protective function. First, the "otter" masonry, hanging over the gap formed at the junction of the roofing material and the pipe walls, closes it from the penetration of precipitation, and forms a space for the installation of waterproofing material. Secondly, its expanded walls become a guarantee of safety - at the place of passage through the roofing, due to the increased thickness, the necessary level of thermal insulation is created.

4 - A metal or other sheet (apron), mounted in the lower part of the otter, forms a kind of ebb, which closes the joint between the brick wall of the pipe and the roofing material.

5 - "Fluff" - this expanded part of the pipe, located in the area of \u200b\u200bits passage through the attic floor. The walls of the "fluff", like the "otters", are thicker than other flat sections of the chimney - this is necessary for fire safety, since the attic floor very often consists of flammable materials, and they should not be allowed to overheat.

6 - Roofing structure.

7 - The riser is a straight section of the pipe, which has an even masonry along its entire height and is located in the attic space from "fluff" to "otter".

8 - Attic floor.

9 - A hood-umbrella is very often fixed on top of the head, which will protect the inner channel of the chimney from water and debris getting into it.

You may be interested in information about what constitutes

The main function of the chimney is to effectively remove the combustion products from the combustion chamber into the atmosphere. For this, the chimney is connected to numerous channels in the furnace structure, with which it must interact harmoniously. If the stove and chimney are built correctly, in accordance with the developed parameters, then during the operation of the heater, good draft should be created inside the channels, which will contribute to the timely removal of smoke into the street. However, at the same time, this should not lead to the fact that the heat generated by it will literally fly out of the furnace "into the pipe". In short, everything needs a “golden mean”.

Chimney duct section

To select the correct cross-sectional parameters for the chimney channel, it is necessary to take into account the power of the furnace, as well as the size of the combustion chamber. The flue ducts will stay clean longer if their inner walls are made smooth, without protrusions and slugs.

For this reason, during the laying of bricks, excess masonry mortar protruding in the seams must be cleaned not only from the outer, but also from the inner walls. Some owners of houses equipped with fireplaces or stoves also use another way to achieve the smoothness of the channel walls - a ceramic pipe, called an insert, is installed inside the brick chimney.

The advantage of this design is not only that the insert has absolutely smooth inner walls. It is round in cross-section, that is, it has no corners, which means that the smoke flows will not encounter obstacles in their path and thus will not create unnecessary swirls and the effect of "reverse draft".

On the right, the illustration shows the "ideal" movement of the flow of hot gases, which twist into a regular spiral in a circular pipe and do not encounter resistance.

In addition, one must take into account the fact that chimneys with a large width, which are still installed in old houses, often have poor draft. This is due to the fact that the air heated in the furnace in a large space inside the pipe cools quickly, which leads to the formation of condensate, which helps to reduce the draft, also smoke the premises, and quickly overgrow the channel with soot. To heat a stove with such a chimney design will require too much fuel. Therefore, it would be most rational to fix them by dismantling the wide upper part of the chimney, then narrowing the shaft and installing a round or square with rounded corners, ceramic, metal or asbestos insert in it.

Now from the form - to the linear parameters. The size of the inner section of the chimney is one of the most important characteristics, since the efficiency of the furnace directly depends on it. The correct ratio of the power of the heater and the dimensions of the pipe section must be observed. Another guideline for determining the correct size of the channel can be the opening of the blowing door - in any case, the pipe section should not be less than the blowing opening.

The section of the chimney shaft, relative to the size of the combustion chamber window, can be determined as follows. For fireplaces with an open firebox, the chimney opening is 1:10 on average. However, depending on the shape of the section and the height of the pipe, this indicator may vary in one direction or another. The approximate values \u200b\u200bof the channel cross-sectional area (in percent) are given in the table below.

Ratiof /F in% (f - cross-sectional area of \u200b\u200bthe chimney channel;F is the area of \u200b\u200bthe combustion chamber window)

Pipe height, m	Sectional shape of the inner channel of the chimney
	ROUND	SQUARE	RECTANGULAR
5	11.2	12.4	13.2
6	10.5	11.6	12.3
7	10	11	11.7
8	9.5	10.5	11.2
9	9.1	10.1	10.6
10	8.7	9.7	10.2
11	8.9	9.4	9.8

It is clear that, in addition to the size of the furnace window, it is necessary to build on the reasonable height of the pipe - it will look absolutely ridiculous, for example, a huge 10-meter pipe on the roof of a small squat country house.

The calculation itself is not complicated. From the table, based on the height of the pipe and the shape of its inner channel, the optimal f / F ratio is determined. Then, based on the area of \u200b\u200bthe furnace window, it will not be difficult to determine the area of \u200b\u200bthe chimney channel. Well, then, using geometric formulas, it remains only to bring the resulting value to linear dimensions - the diameter for a round pipe or the length of the sides for a rectangle.

This calculation algorithm is implemented in the calculator below.

Despite the wide range of modern and modern heating systems, solid fuel stoves are not at all going to give up their popularity. This is quite understandable - the presence of such a heating structure gives a certain feeling of autonomy - even under the most unfavorable circumstances caused by interruptions in the supply of other energy carriers, a stove with a supply of fuel will help both heat the house and prepare food for the family.

But the oven will only work efficiently and with the proper level of safety if it is designed, folded or manufactured in accordance with all the necessary requirements. And one of the key conditions for the functioning of the furnace is a well-thought-out and reliable system for removing combustion products -. There are several options for the equipment of this system - from laying out a classic pipe “the old-fashioned way” of brick, to using completely new, sometimes even unexpected technological solutions using modern composite materials. And at the peak of popularity in this matter in our time, there are probably sandwich pipes for ovens.

What are sandwich pipes for furnaces, how they differ, what you need to know about their selection and the basic rules for designing a system - all this is in this publication.

What are sandwich pipes and their main advantages

The developers of sandwich chimneys set themselves the task of minimizing the drawbacks characteristic of almost all chimneys, regardless of the material of their manufacture.

Any chimney is subject to negative destructive influences both from the inside and outside. The combustion products have a high temperature and a very aggressive chemical composition, which leads to erosion or corrosion of the materials of the inner channel. In addition, over time, the chimney channel becomes overgrown with soot, which reduces the permeability of the chimney, and as a result, the efficiency and degree of safety of the furnace.

Outside, in open areas, external factors act on the pipes - high humidity, precipitation, fluctuations in air temperatures outside. In addition, the temperature difference outside and inside the chimney leads to the active formation of condensation - and this, in turn, increases the likelihood of soot build-up.

"Classic" brick chimneys, although they are considered time-tested, have a whole bunch of disadvantages.

• First, the rectangular section of the channel is by no means optimal - unnecessary vortices of the gas flow inevitably occur in it. Reducing overall traction.
• Secondly, it is impossible to achieve ideal smoothness of the channel walls - the porous structure of the brick will still contribute to soot deposits.
• Thirdly, the brick chimney itself is a very massive structure, rather complicated to build and requiring a reliable foundation.

How is a brick chimney laid out

If this option is chosen, then a number of important rules must be strictly observed. How to fold a brick chimney on your own - in a special publication of our portal.

• And fourthly, even high-quality brick, due to the influence of a whole complex of negative influences, is defeated by erosion, and the picture of crumbling chimneys is by no means a rarity.

This means that for the chimney to be optimal, it must be made with a round section, smooth inner walls, from a heat-resistant material that is resistant to erosion and corrosion. and light enough not to burden the entire oven structure. It would seem that modern types of stainless steels meet all these requirements. However, such a simplified scheme is impossible for a number of reasons:

• Any metal has a high thermal conductivity, and a high temperature difference inside the chimney and outside can have a destructive effect on thin walls, and most importantly, leads to abundant condensed water vapor, always contained in the composition of combustion products.
• The rapid cooling of gases in open sections of the chimney will inevitably lead to a decrease in the furnace draft.
• The sections of the metal pipe located inside the building are heated to very high temperatures, and this is unsafe both from the fire safety point of view, and from the standpoint of a high probability of accidental injury - burns.

This complex of problems would be completely or as much as possible solved by creating a sandwich chimney structure. The inner channel and the outer surface of such a structure are two separate metal cylinders, separated by an interlayer of heat-resistant heat-insulating material with a pronounced low thermal conductivity.

The inner bore should always be made of a special type of stainless steel, with reliable weld penetration - usually argon welding is used.

The outer casing is also metal, but options are already possible here. Of course, the most resistant to external influences will be a stainless steel casing. However, sometimes in order to save money, cheaper options are also purchased, in which the outer pipe is made of galvanized steel.

Basalt fiber mineral wool is most often used as a thermal insulation layer, as the most resistant to high temperatures. The high density of basalt wool (from 120 to 200 kg / m³) provides the necessary structural strength. The thickness of this layer can vary - from 25 and even up to 100 mm. It depends on the parameters of the heating equipment and, to a certain extent, on the climatic conditions of the region.

The great convenience of such a design is that it carefully considers the installation of individual parts into a single system. For this, connecting units are provided in the form of sockets and narrowed sections, special clamps, stoppers, sometimes flanges, etc.

Such a chimney system for the furnace immediately acquires a number of important merits :

• The mass of the entire chimney system assembled is not so great, that is, it is not necessary to strengthen the foundation of the furnace and its structure, as is the case with a brick pipe.
• The chimney can be positioned on brackets vertically along the outer wall of the building. And this is a simplification of assembly, especially when passing through ceilings, and a significant saving of useful space inside the premises.
• The system is very flexible in terms of its placement possibilities. Manufacturers provide a wide range of additional units and components that allow you to quickly and reliably assemble a chimney of the required configuration. It becomes possible to bypass possible obstacles without resorting to large-scale alterations to the structure of the house.

• The temperature difference outside and inside is compensated for by a thermal insulation layer. This stability guarantees normal, sustained traction while condensation and soot build-up are minimized.
• The outer surface of a sandwich pipe, when properly assembled, does not heat up to critical temperatures, that is, the safety of the chimney operation is significantly increased.
• The assembly of such a chimney, subject to all technological recommendations, is an accessible and intuitive measure that does not require any special training.

Such chimneys have certain limitations :

• A quality kit will be quite expensive.
• Over time, under the influence of high and low temperatures, signs of depressurization may appear at the joints of individual units - this requires special attention: regular checks and, if necessary, preventive work.
• Limited overall service life. Despite the fact that high-quality stainless steel is highly resistant, the aging process does not bypass it either. As a rule, manufacturers guarantee up to 15 years of trouble-free operation of their products. However, any other chimney for such a period will certainly require any repair and restoration work.

How to choose a metal sandwich chimney

As already mentioned, the cost of such a chimney system is quite high, and the replacement of poor-quality pipe sections can result in considerable costs. Therefore, it is very important to be able to correctly evaluate the product when choosing, so that disappointment does not come after one or two years of operation.

The selection criteria can be roughly divided into several categories. So, first of all, the quality of the materials used in the production of sandwich pipes is assessed. The necessary linear parameters are selected - that is, the diameter of the chimney, the height of the future pipe, the thickness of the insulation layer. It is important to immediately think over the features of the structure being created in order to assess whether all the components are available on sale for its installation.

Assessment of the quality of materials of manufacture

To the untrained eye, all stainless alloys appear the same. The new pipe casts shine - but this is not at all a criterion for the quality of the metal.

The same "beautiful and shiny" pipe after a short period of time can deform and even simply burn through - alas, there is a lot of evidence of this on the Internet. And this situation is a direct road to fire or carbon monoxide poisoning.

Unfortunately, we have to admit that the increased demand for such chimneys has given rise to the "shadow sector" of their production, where materials are used that are of little use for such purposes. There is another situation, when a completely high-quality sandwich was applied in conditions for which it was simply not designed. For example, a pipe that is perfectly suitable for a gas boiler is not suitable for use with a solid fuel stove.

Stainless steel grade

When choosing a sandwich pipe, you need to focus on the steel grade that is used primarily for the inner channel. This parameter must be indicated in the passport documentation of the product, if, of course, it is issued by a bona fide manufacturer. If the steel grade is not indicated, then it is better to look for another option.

So, the following stainless steel brands can be found:

- AISI 430... This steel is one of the most inexpensive. It is quite suitable for the outer lining of a sandwich, since its resistance to atmospheric phenomena is quite sufficient. But for the inner pipe, it is categorically not suitable. Its composition predetermines poor weldability, that is, obtaining a sealed seam is very problematic. Such steel does not meet the requirements of increased heat resistance.

- AISI 439... This alloy is enriched with titanium additives, which significantly increases its corrosion resistance and mechanical strength. Pipes made of such steel are quite suitable for any gas installations, as well as for solid fuel boilers and furnaces, but only with a small thermal power.

- AISI 316... This steel has a pronounced corrosion resistance to almost all aggressive substances. Thermal resistance is average, therefore the pipe is suitable only for equipment operating on gas.

- AISI 304... Steel is not of the highest heat resistance, so it is usually not used by serious manufacturers from being used as an internal channel. Suitable for outer casings perfectly.

- AISI 321 and AISI 316i... They have excellent heat resistance and good ductility and are easy to weld with high quality. Such pipes are quite suitable for most types of boiler and furnace equipment, as they can withstand heating up to 850 ° C without deformation.

- AISI 310S. Fully universal steel that can withstand temperatures up to 1000 ° C. It is quite suitable even for powerful solid fuel furnaces and boilers operating on the principle of afterburning pyrolysis gases. The only conditional drawback is the high price.

Knowing the parameters of your oven, you can select the optimal grade of stainless steel.

Do not forget about one more way to check stainless steel. He, of course, will not give an accurate picture, but it will help to immediately avoid buying a low-quality fake:

It is necessary to take an ordinary magnet and try to "glue" it to the inner wall of a vertically standing sandwich pipe. The magnet doesn't have to be held - ideally it will just slide down. If it stays in place or goes down with visible braking, the "black" component of such steel is too high, and the pipe is unsuitable for the chimney.

Insulation material type

As already noted, only basalt mineral wool should be used as an insulating material for the thermal insulation layer. In no case, no matter how attractive the price may seem, you should not purchase a sandwich pipe filled with glass wool. The thermal conductivity coefficient of glass wool is no worse, then the heat resistance is completely different. At temperatures of about 300 ° C, its sintering begins, sagging in size, and all its advantages are reduced to zero. In addition, fiberglass is very brittle, and the insulation layer does not differ in volumetric stability, it is prone to shrinkage.

In really high-quality sandwich pipes, manufacturers use insulation from leading brands - ROCKWOOL, PAROC and the like.

Chimney diameter and insulation thickness

Manufacturers provide a fairly wide range of diameters. So, models are produced with an inner pipe from 110 to 300 mm, with a different thickness of the insulation layer, that is, with a different outer diameter of the structure.

The main parameters of a sandwich pipe are the diameter of the inner channel, the thickness of the insulation and, accordingly, the size of the outer casing

If new equipment, a boiler or a stove is purchased, then the required chimney diameter must be indicated in the passport data - this value should be adhered to. It is more difficult if the chimney is planned to be installed on a brick or homemade one - here it is important not to be mistaken with this parameter.

In this case, you can do it in several ways. The first, simple one, is to navigate according to the table showing the dependence of the thermal power of the equipment and the diameter of the chimney.

Thermal power of solid fuel furnace		The minimum section of a rectangular chimney	Cross-sectional area of \u200b\u200bthe pipe	The minimum diameter of the inner pipe of the sandwich chimney
kW	kcal / hour
up to 3.5	up to 3000	140 × 140 mm	19600 mm²	158 mm
3.6 ÷ 5.2	3000 ÷ 4500	140 × 200 mm	28000 mm²	189 mm
5.3 ÷ 7.0	4500 ÷ 6000	140 × 270 mm	37800 mm²	220 mm

You can also be guided by the approximate consumption of the existing stove of this or that fuel. For the calculation in this case, the following formula is used:

S \u003d Vg /Wg

S - cross-sectional area of \u200b\u200bthe flue duct.

Vg - the volume of combustion products.

Wg - the speed of movement of gases through the chimney (2 m / s is considered optimal).

Thus, to calculate the diameter, you need to apply the formula for the area of \u200b\u200ba circle:

d \u003d √4 ×S /π \u003d √ (4 ×Vg /Wg) /π \u003d √2 ×Vg /π

The quantity remains unclear Vg.It is calculated by the following ratio:

Vg \u003d М × Vу × (1 +T / 273) / 3600

MIs the total approximate mass of fuel burned in one hour.

Vу- specific volume of combustion products from combustion of 1 kg of fuel.

T - temperature at the outlet of the chimney

273 - the difference between the temperature zero value in degrees Celsius and Kelvin.

3600 - the number of seconds in an hour to bring the value to a single value.

So, the formula looks like this:

d \u003d √ (2 × M ×Vу × (1 + T / 273) / (3600 × π))

The values Vуand Tyou can accept tabular, using the table below.

Fuel type	Average calorific value of fuel, kcal / kg	Specific volume of combustion products from combustion 1 kg, m³ / kg	Chimney outlet temperature, ° С
Firewood, average moisture level 25%	3300	10	150
Peat lumpy or loose, air-dried, humidity up to 30%	3000	10	130
Peat in briquettes	4000	11	130
Brown coal	4700	12	120
Coal	6500	17	110
Anthracite	7000	17	110

Surely, the formula will seem "heavy" to many, not conducive to independent calculations. To simplify the task, below is a calculator, which already contains the necessary arithmetic relations.