How to properly install a chimney from sandwich pipes. Installation of stainless chimneys: step-by-step instructions

Installing a chimney in the form of a sandwich, consisting of a pipe, insulation and an outer shell, allows you to optimize the operation of the heating and smoke exhaust systems. Such a chimney provides good draft, is less clogged and almost does not heat up from the outside, thereby reducing the risk of burns and fires. All the advantages of a combined chimney are fully realized only with proper installation and the use of high-quality materials.

Combined type smoke exhaust structures have replaced the usual asbestos and metal pipes, brick and ceramic smoke shafts due to a number of advantages:

There is less risk of burns and fire - during operation of the heating unit, only the inner chimney pipe becomes very hot, the temperature of the outer shell changes slightly.
Better traction - an insulated pipe warms up faster after igniting the fuel, since it does not give off heat to the external environment.
Fewer soot deposits are formed - the smooth inner pipe facilitates the removal of smoke and does not allow condensation to linger; most of the combustion products do not have time to react with water and form solid compounds.
The inner pipe is protected from the mechanical influence of the external environment, and the outer shell is protected from sudden temperature changes and the effects of aggressive substances that make up the smoke.
Less condensation forms on the outer surface of the chimney, since the temperature of the shell and the external environment differs slightly.

However, any complex solution inevitably has disadvantages. The sandwich chimney is no exception; it also has disadvantages:

high price,
heavy weight,
complex installation.

Design features and materials for manufacturing

In construction, a sandwich is a name given to three-layer building materials and structures. In a smoke exhaust system, a sandwich is understood as a combination of an internal smoke channel, a heat-insulating layer and an outer shell. Sometimes you can get a sandwich chimney based on an existing pipe or shaft by adding the missing layers.

To construct a sandwich chimney, combinations of materials or ready-to-assemble sections can be used:

Materials	Design Features	pros	Minuses
steel, backfill brick or rolled non-combustible insulation	a single-wall smoke duct made of a steel pipe is installed, an external brick shaft is erected, the space between the layers is filled with insulation	low price of materials, easy installation
steel, mineral wool (ready-made sandwich sections)	the chimney is assembled from ready-made non-separable sections consisting of two steel pipes and basalt insulation between them	low cost, Ease of transportation and installation, availability of all necessary connecting and additional elements for sale, Relatively light weight of the structure, Easy to replace failed sections, relatively light weight, configuration variability	short service life - 5-10 years, the outer pipe can heat up
heat-resistant ceramics, steel, mineral wool (ready-made sandwich sections)	the chimney is assembled from ready-made non-separable sections: ceramic smoke channel, basalt insulation, steel outer shell	service life - 20-25 years, average price range, ease of transportation and installation, availability of shaped elements for sale, configuration variability	Unloading areas are required every 2 meters in height, the outer pipe can heat up
heat-resistant ceramics, foam or expanded clay concrete, mineral wool	the chimney is assembled in sections: ceramic chimney, basalt wool, external shaft made of foam or expanded clay concrete		service life – up to 40 years, absolute fire safety
heat-resistant ceramics, brick, mineral wool	the chimney is assembled in sections: ceramic chimney, basalt wool, external brick shaft	average total cost of the chimney, long service life of the smoke duct - up to 40 years, fire safety, no special tools required for the construction of the shaft	a foundation is required, the shaft can only be vertical, The shaft material is hygroscopic, The tightness of the seams is easily broken, which is why moisture can get into the insulation, reducing its thermal insulation properties

How to assemble a chimney sandwich? Every novice stove maker asks this question, because sandwich chimneys firmly occupy a leading position in the construction of fireplaces and stoves, displacing brick and metal chimneys. Their popularity is easily explained: sandwich chimneys are safe, practically do not heat up, are less susceptible to blockages, and in addition, they are easy to install. Our article will tell you how to do this correctly.

This type of chimney includes multi-layer prefabricated chimneys made of stainless steel or ceramics. They are produced in the form of ready-made elements assembled into a single structure. Both types of sandwich chimneys have their own characteristics, but their installation is generally similar.

Stainless steel chimneys consist of an inner pipe, resistant to high temperatures, wrapped in a layer of non-flammable heat-insulating material, protected from external influences by an outer pipe made of stainless steel or, for cheaper chimneys, galvanized steel. The inner pipe can be made of either metal or ceramic; such chimneys are called combined.

Video - installation of a combined sandwich chimney

Ceramic chimneys are a pipe made of heat-resistant ceramics, coated on the inside with a high-strength glaze, and wrapped on the outside with thermal insulating mats. This structure is placed in an outer shell made of expanded clay or foam concrete blocks.

Thanks to their design and thermal insulation layer, sandwich chimneys from the outside never heat up to high temperatures that could lead to a fire. This feature, as well as quick and easy installation, make them popular among builders.

Metal and ceramic chimneys, despite the similarity in design, have differences, the main one being weight. A full-fledged ceramic chimney can weigh about a ton, while the weight of a stainless steel chimney does not exceed a couple of hundred kilograms. A ceramic chimney requires a foundation, while a metal chimney requires unloading areas at each floor level. At the same time, ceramic chimneys are more durable and will last you at least 20-25 years. And metal structures, especially when operating fireplaces with straight chimneys or stoves such as potbelly stoves, burn out after 5-10 years and must be replaced.

Installation of a stainless steel sandwich chimney

Installation of metal chimney elements is not difficult, the main thing is to observe the direction of connecting the elements “through smoke” and “through condensate.” What does it mean? When the stove is fired, smoke rises. If an obstacle is encountered in its path in the form of even a small plane formed by the previous element and facing downwards, solid smoke particles settle on it, and the chimney becomes clogged over time. With condensation, the opposite is true: it flows down, lingering on the ribs of the upward-facing elements, and penetrates the insulation, worsening its thermal insulation and fire-fighting properties. This is clearly visible in the figure.

Assembly of chimney elements “for smoke” and “for condensate”

When working, be sure to use thick gloves - thin metal can cut your skin. When installing elements, it is necessary to check their verticality using a level and ensure that the distance to non-insulated combustible structures does not exceed 25 cm for sandwich elements and 60 cm for single pipes.

Chimney sandwich made of metal: installation sequence

1. A single metal pipe is installed at the outlet of the furnace smoke collector. Its height determines heat transfer into the room. The pipe is placed “along the smoke” - put on the pipe from the outside. A damper is placed before or after the pipe to block the chimney. All joints are coated with heat-resistant sealant.

2. A starter sandwich chimney is installed on a single pipe: a double pipe, closed at the bottom end. Sandwich pipes are subsequently installed on it. The starting element is mounted on the pipe “along the smoke” and put on the pipe. The joints are also coated with sealant.

3. Begin assembling the chimney from the necessary elements; possible chimney elements are shown in the figure. Pipes and elbows are installed “along the condensate”, that is, they are inserted inside the previous element so that the draining condensate does not get into the fiber insulation. It is also advisable to coat the joints with sealant.

4. When passing through the ceilings, unloading platforms are used, and the pipe itself is tightened with clamps every two meters and secured to rigid structures. It is better to do this in places where the pipes are connected, this gives additional strength to the entire chimney. The pipe is separated from combustible structures by a layer of basalt wool placed in a special box.

5. For pipes with many bends and branches, it is mandatory to install inspection elements with a window for cleaning. They are installed in places with open access to the pipe, also “through condensate”.

6. Passage through the roof and sealing is carried out using a special lining - a conical roof, and an apron. The upper part of the pipe is equipped with a head or deflector.

7. During the first fire and heating of the pipe, the sealant hardens and creates additional strength and impermeability to smoke and condensate.

Video - installation of a stainless steel sandwich chimney

Installation of a ceramic sandwich chimney

The main difficulty in installing ceramic sandwich chimneys is arranging a reliable foundation, as well as assembling the outer shell. For the shell of chimneys, blocks of foamed expanded clay concrete are used - they are light, durable and not afraid of moisture. Ceramic pipes are heavier than metal pipes, so installation is best carried out by a team of two or three people.

Ceramic sandwich chimney: installation sequence

1. Check the presence and completeness of all chimney elements in accordance with the project: pipes, blocks, insulation, additional elements.

Insulation - basalt wool

2. Level the foundation using sand-cement mortar and wait several days for it to gain strength. Two or three layers of roofing material are laid on top of the screed - the waterproofing will not allow moisture from the soil to penetrate the walls of the chimney.

3. Install the base block first. This is a very important stage - any deviation from the vertical of this block will lead to a strong distortion of the entire chimney, so at this stage it is necessary to use a level.

4. After fitting and leveling, the block is placed on roofing felt using the same cement-sand mortar and finally leveled.

5. For greater stability, cobblestones, crushed stone or broken bricks are placed inside the block and filled with cement-sand mortar or concrete.

6. All the following blocks are fastened together using a special solution that is resistant to high temperatures - it is purchased together with the chimney kit. The solution is applied onto a metal template with a spatula.

7. To install some elements - tees, revisions - it is necessary to make a cut in the blocks. It is performed using a grinder with a diamond-coated disc using a ready-made template included in the kit.

8. The first element of the pipe is a condensate collector with an outlet; it is installed in a block with a cut hole for the ventilation door so that the outlet faces the cut in the block.

9. A heat insulator is laid around the first pipe element - basalt wool mats.

10. The next pipe element is placed on the condensate collector, connecting the elements with a special sealant.

11. Continue assembling the chimney. Blocks are connected to blocks with a heat-resistant mortar, pipes with a sealant. At the same time, do not forget to combine inspection elements and tees with cuts in the blocks, and wrap the pipes with heat-insulating mats.

12. The passage of the chimney through the ceilings is secured to the rafters or beams using metal brackets, thereby increasing the stability of the chimney.

13. When the chimney exits through the roof, they try to make a minimum gap between the block and the roofing. The junction strips are installed and the pipe is sewn up with a suitable material, in this case, profiled metal.

14. To prevent moisture from getting inside the chimney shell, it is covered with a concrete slab with a hole for the pipe itself. If it is not possible to find a finished slab, you can make formwork with reinforcement and fill it with concrete 5-10 cm thick.

Formwork for concrete slab - pipe slabs

15. A cone-shaped head is placed on top of the pipe; it is also included in the delivery package.

Video - installation of a ceramic sandwich chimney

A properly installed chimney is not afraid of either moisture or overheating; it successfully copes with the task of removing smoke from a stove, fireplace or boiler. Timely installation will extend its service life, so before assembling a sandwich chimney, carefully consider the location of all inspection elements, and the operation of your chimney will become convenient and safe.

FORUMHOUSE users are well aware that high-quality installation of a metal chimney directly affects the safety of living in a cottage. We have already written about that. It's time to talk about the features of installing a steel chimney.

1. What is a sandwich chimney

Despite the large selection of materials for installing smoke exhaust systems, reliable steel sandwich chimneys are most widely used in private housing construction.

A sandwich type chimney consists of two pipes of different diameters inserted into each other, and all the free space between them is a place to be filled with non-combustible insulation - mineral wool.

Mineral wool simultaneously plays the role of insulation and insulator.

Sandwich chimneys have the following main advantages:

High installation speed and low cost compared to brick chimneys;
Low weight of the smoke removal system;
Smooth internal walls of the chimney provide good draft and help reduce soot formation;
The use of acid-resistant stainless steel grades guarantees a long service life of the chimney.

The temperature of the flue gases directly depends on the type of heating boiler and the type of fuel used. The higher the temperature of the exhaust flue gases, the more the pipe and, accordingly, all the structural elements through which it passes, heat up. The following table will help you understand the dependence of the flue gas temperature on the type of boiler and the type of fuel used.

It should be remembered that unprotected wood begins to char at a temperature of 200 ° C. Well-dried wood can ignite from an open flame source at a temperature of 270-290 ° C. And if a wooden surface is subjected to constant heating for more than 24 hours in a row, then it can spontaneously ignite already at a temperature of 170° C. Therefore, when installing a sandwich chimney, it is important to observe all fire safety measures. And any mistake made at this stage can lead to dire consequences - fire and loss of property.

Urban:

– Two of my friends’ houses burned down due to an improperly installed sandwich chimney. Moreover, in both cases, the fire occurred in the place where the chimney exit was located through the wooden ceiling.

According to statistics, up to 80% of fires occur precisely because of improperly installed chimneys. Therefore, when choosing and installing a chimney, you must adhere to SNiP 41-01-2003 “Heating, ventilation and air conditioning.”

2. Chimney: distance to the floor slab and correct penetration

As practice shows, the greatest number of questions arise when calculating the distances from the chimney to wooden floors.

VadimPro:

– I built a house with a distance between the rafters of 60 cm. And only then I found out that according to existing standards, my chimney does not fit into this distance.

And again SNiPs come to our aid:

vova230:

– According to the standards, when driving through wooden floors, it is necessary to maintain a distance of 38 cm from the inner pipe of the sandwich to the combustible structures. All this space must be filled with fireproof material. If the standard passage does not provide this distance, then the dimensions of the furnace passage must be further increased.

If the chimney is laid through protected wooden structures, the distance can be reduced to 25 cm.

Protection of wooden structures - joists, ends of rafters, sheathing - is ensured by a galvanized sheet with an asbestos sheet of at least 5 mm thick laid between it and the wood.

Galvanization performs the following functions:

Prevents the spread of fire in the ceiling;
Provides uniform heat dissipation;
Shields and reflects thermal radiation coming from the pipe.

In the case of tunneling between floors with a single-pipe steel chimney, the distance to unprotected wooden structures must be at least 50 cm!

Also, the parameters of the chimney should be calculated in such a way that the chimney pipe passes through the ceiling entirely - without joints with other elements. The chimney itself is installed through a passage pipe-cut, which is a metal box.

Specialist from the portal website Alexey Telegin from Moscow recommends:

– According to the standards, the thickness of the cutting (metal box) should exceed the thickness of the ceiling by 7 cm.

Sealing the floors where metal pipes pass from the stove with basalt fiber cardboard

Installation of polyurethane foam chimney

The process of installing grooves in a wooden floor can be divided into a number of successive steps:

1. Cut a hole in the ceiling with a size of at least 700x700 mm.

2. If necessary, remove or strengthen the floor beams.

3. We sew up the perimeter of the cut opening with fireproof materials, super insulation, etc.

4. For tightness, we place a sheet of basalt cardboard under the superisol.

5. We make a supporting frame from a galvanized profile, which is used when installing gypsum boards.

6. The dimensions of the frame are calculated for the PPU (ceiling-passage unit) fastening units.

7. We close the opening with sheets of mineralite or superisol with a hole for the passage of the inner part of the polyurethane foam.

8. We fix the foam.

9. Install the sandwich pipe.

10. We insulate the lower part of the polyurethane foam and the space around it with non-flammable insulation, this will avoid freezing and the formation of frost and condensation.

It is better to install and calculate the smoke removal system at the stage of designing the house!

It is also important to pay attention to how the pipes are connected to each other. There are two methods - “by smoke” and “by condensate”.

Docking “through smoke” - the pipe of the lower bend of the sandwich goes inside the pipe of the upper bend of the sandwich. In this case, flue gases move freely up the walls of the pipe;
Docking “by condensate” - the inner pipe of the sandwich: the upper one is inserted into the lower one, the outer pipe of the sandwich: the lower one is inserted into the upper one. With this installation, the pipe allows condensate to pass through, it flows down freely and does not flow out along the outside of the chimney, which can lead to a fire.

Kotlasky:

– The condensate pipe is usually installed on modern gas boilers, because they have a low temperature of the outgoing smoke.

For metal stoves and cast iron potbelly stoves, the smoke temperature is about 300°C; the steam that is released when burning wood begins to condense at a temperature of less than 100°C. At the moment of kindling, steam, falling on the cold walls of the chimney, is deposited in the form of water droplets, which roll down the smooth walls of the chimney down into the condensate collector.

The condensate collector is installed outdoors. It is better to assemble a sandwich chimney “by condensate”.

3. Features of penetration through the roof

Penetration through the roof is done according to the same principles as penetration through ceilings. Let's find out if it is correct that when driving through rafters, the distance to protected wooden structures can be reduced to a size of 150 mm.

Alexey Telegin:

– It is assumed that the chimney cools down when passing through the roof, and the space around it is well ventilated, so you can reduce the gap to the protected rafters. In my opinion, this may be true for a cold roof, but with an insulated roof, you need to apply the same standards and distances as for interfloor ceilings.

Today, the sandwich design chimney is the most popular. Practical, aesthetic, functional... And most importantly, installing a sandwich chimney with your own hands is a fairly simple and safe undertaking if you have purchased really high-quality and certified materials in advance. Chimneys of this type really have many advantages: no condensation, negligible soot formation, high fire safety, simple maintenance, relatively light weight chimney, aesthetics. And finally, sandwich pipes are simply ideal for wooden buildings, which is traditionally the case with a bathhouse. And what to do, how and in what order - you will learn from this article.

How to make and assemble a sandwich pipe yourself?

The finished “sandwich” chimney consists of segments, each of which is one meter long and is inserted into the other during installation. Now let’s figure out exactly how to assemble a sandwich chimney and from what materials.

So, the design of a sandwich chimney is as follows: it is an inner and outer pipe, between which there is a layer of thermal insulation. The inner pipe is made of stainless steel, but the outer one can be made of a variety of materials, even copper and brass. But it is not recommended to take galvanized pipes for the chimney: in heating and cooling mode, it will change its diameter, whereas stainless steel practically does not.

Important! If the stove in the bathhouse is heated with solid fuel, then the sandwich pipe can only be used from high-quality stainless heat-resistant steel.

Most often, basalt fiber or mineral wool, which has good thermal insulation properties, is used as insulation. Experienced stove makers, for example, advise using Rockwool WIRED MAT 80 basalt wool as thermal insulation. Its thickness can vary from 25 to 60 mm.

Expanded clay and polyurethane are also used as internal insulation for such pipes. The only problem when laying thermal insulation between the outer and inner pipes is that the material has to be overlapped with an undercut of half the thickness and an overlap of 10 cm. Or you can even stuff it all by hand, if it works out neatly.

Sandwich pipes are also connected in different ways: by flange method, by bayonet method and by a “cold bridge”, and also “under smoke” and “by condensate”. “By smoke” the chimney is assembled for the purpose of fully guaranteeing that no carbon monoxide will enter the house or bathhouse. And “condensate” - so that the condensate formed due to the temperature difference can freely flow down the pipe.

In the first case, the smoke does not encounter any obstacles and, under the influence of draft, quickly comes out, but condensation can get inside the sandwich if the joints are carelessly sealed. As a result, the internal insulation will suffer a lot. But in the second method, the inner pipe of the sandwich fits into the socket of the lower one, and moisture cannot get inside the pipe in any way. But the smoke, if it finds even the slightest crack, will find a way out. What to choose? Gas is harmful to human health, and condensation is harmful to the durability of the chimney. The only way out is to carefully seal all the cracks and joints with any method, and that’s it.

For the internal pipes of a sandwich chimney, we recommend installing it “on condensate” so that the condensate itself does not fall on the pipe seams and there is no leakage. And, despite their double layer, sandwich pipes still require high-quality insulation from those areas that are most fire-hazardous - from beams, roofing and ceilings. And the sandwich cannot be used as the first pipe that is connected directly to the stove.

So, knowing the technology, you can easily make a high-quality sandwich chimney with your own hands - from materials you personally purchased (preferably with quality certificates).

Installing a sandwich chimney in a bathhouse in stages

The installation of a sandwich pipe for a chimney itself is not difficult. Since sandwich pipes are as fireproof as possible, even a person who is very far from construction can connect and secure them correctly.

The “sandwich” chimney is installed from the bottom up - from the stove to the roof, and the outer pipe needs to be “put” on the inner one. In general, there are several important points for installing a sandwich. Let's go into more detail.

Stage I. Connecting the chimney elements

When installing a sandwich chimney, pay attention to the fact that one of the ends of the pipe is always narrowed with a slightly smaller radius. It just needs to be inserted into the previous pipe. Due to the fact that almost no soot accumulates in such a chimney, it is easy to remove condensate from it - and it is better to additionally install special tees for this.

Stage II. Option 1. We draw the chimney through the wall

If the chimney will exit through the wall, it will have to be dismantled and the mounting locations for the bracket reinforced. Next, we assemble the outer bracket and attach two corners to it like runners - so that you can move the tee without any problems during the installation of the chimney from sandwich pipes, and nothing gets stuck.

The wall itself can be covered with plywood one centimeter thick and an asbestos sheet secured with screws over its entire area. On top of that is a solid sheet of galvanized metal 2x1.20 cm. We cut a square hole in the sheet itself for the passage and secure it with screws. Finally, we coat the bracket with metal varnish to protect it from corrosion. Next, drill the required hole in the adapter and put the sandwich into it.

When building a chimney, they also use such a concept as a concession - this is the space that we specially leave between the smoke channel and the wall.

Important point: calculate the first connecting element of the chimney so that the first sandwich pipe connects to the next one above the ceiling cut. After all, visual inspection of the most fire-hazardous parts is important!

Stage II. Option 2. We draw the chimney through the roof

When running a sandwich pipe through the roof, you must first take a galvanized steel sheet, attach it from the inside to the hole, and remove the pipe. Only after this we attach the sheet to the roof. If necessary, it can be additionally placed under the edge of the roof.

Attention! If the bathhouse has a flat roof, then the chimney above it should rise at least one meter. If the height of the chimney from the roof to the deflector is more than 1.2 meters, then it is necessary to install guy wires with crimp clamps.

If the roof is made of combustible materials, it must be protected from fire. And to do this, we install a deflector with a spark arrestor mesh with small cells on the chimney, which rises above the wooden tiles or bitumen.

Stage III. We fix the chimney

We fasten all tees, elbows and other elements with clamps, and fasten the tee with a support bracket. If the upper part of the chimney remains unsecured, it is better to secure it. At least with the same 120 degree stretches. Here's how additionally you need to fasten the butt joints: sandwich pipes to each other - with crimp clamps, pipes with other elements, such as adapters and tees - with the same clamps, but on both sides.

By the way, you can make a support bracket for the chimney yourself: to do this you need to take two angles of 30 and 50 mm, and use an angle grinder, a drill and M10 and M8 bolts to build everything.

Stage IV. Completion of installation

After completing the assembly, be sure to remove the protective film from the pipes. The optimal length of the chimney is 5-6 m from the stove grate to the top - pay attention to this. And we seal all seams and gaps.

To do this, you will need a heat-resistant chimney sealant that is designed for temperatures of at least 1000˚C. You need to apply it like this:

For internal pipes - on the outer surface of the upper internal pipe.
For external pipes - along the outer surface.
When switching from a single-walled to a double-walled pipe - from the outside, around the circumference.
When connecting a single-wall pipe and other modules - as in the last version.

When everything is ready, be sure to check the most dangerous heating zones of the chimney for temperature. And so that later cleaning the chimney is simple and easy, it must include an inspection - this is a special removable part or hole with a door.

Installation of a sandwich chimney is very simple and easy due to the simplicity of the design and light weight - if you have already decided on the project and purchased the material, feel free to roll up your sleeves!

If you are the owner of a private house or cottage, then you probably know that an integral stage in the construction of any structure heated with a fireplace or stove is the installation of a chimney. The main purpose of this functional element is to remove combustion products from the firebox that pose a health hazard, as well as to provide reliable draft necessary to maintain combustion processes, while the draft level is determined by the diameter of the chimney and the height of the smoke channel. Among supporters of doing all the housework independently without the involvement of specialists, chimneys of the “sandwich” design are the most popular, which is explained by their functionality, practicality, high aesthetic characteristics and other equally significant advantages. However, the prevalence of sandwich chimneys among ordinary craftsmen is largely due to the safety and ease of their installation, of course, provided that only certified and high-quality materials are purchased. Despite the fact that the installation of sandwich chimneys involves connecting structural elements and auxiliary parts in the correct sequence, during their assembly it is necessary to observe a number of certain nuances, neglect of which can significantly reduce the performance characteristics of the structure. Considering the relevance of this problem, in this article we will consider the technology for installing a sandwich chimney with our own hands, as well as the main types and features of this structural element.

Construction of sandwich chimneys: design features

A sandwich chimney is a metal or ceramic structure consisting of several segments, each of which is one meter long and is inserted into the other during the installation process. To put it simply, the design of a sandwich chimney is represented by an inner and outer pipe, between which there is a layer of heat insulator, most often basalt fiber or mineral wool, characterized by high thermal insulation properties, resistance to open flames and immunity to a number of chemicals. Thanks to this three-layer structure, this design is called “sandwich”. In most cases, stainless steel, characterized by increased anti-corrosion properties, is used to make the internal pipe contour, and less durable galvanized metal is used for the external pipe, in order to save money.

Important! When choosing a material for the manufacture of the internal contour of a sandwich chimney pipe, it is necessary to be guided by its ability to withstand elevated temperatures, and for the external one - by its strength characteristics, since it must be sufficiently rigid, which will help preserve the original configuration of not only the pipe, but also the entire structure in in general.

Main components of a sandwich chimney system

It is logical that only straight pipes cannot be used to install a system used for smoke removal. This is explained by the structural features of the building: the sandwich chimney must go around its elements, pass through the ceilings and roof. In this regard, during its assembly, sectional fragments are used, the connection of which is carried out using additional elements. To understand this in more detail, let’s consider what elements a sandwich chimney consists of.

The structure of the sandwich chimney system includes the following main elements:

Sandwich pipes;
Tees are structural elements of the system that are used to connect the chimney to the fireboxes of fireplaces and stoves, as well as in the branching areas of the chimney channel;
Elbows are elements designed for installing chimney bends. For these purposes, models with bends of 15, 30, 45 and 90 degrees are used;
The condensate collector is another part of the chimney designed to drain and remove moisture that accumulates on the internal walls of the chimney as a result of temperature changes;
Roof penetration elements - parts of the system designed for installation of a sandwich chimney in places where it overcomes roof structures while simultaneously ensuring effective thermal and waterproofing;
An inspection tee equipped with a door is a device designed to monitor the cleanliness of the smoke channel and remove soot;
The mouth is a structural element necessary for arranging the upper edge of the chimney;
Support console - a structural element necessary for installing a wall or floor base under the chimney;
Wall clamp is a device designed to securely fix the chimney relative to the wall.

Advantages and disadvantages of sandwich chimneys

High aesthetic characteristics and spectacular appearance;
Thanks to their design features, sandwich chimneys can be effectively combined with various models of stoves and boilers;
Due to the lightness and versatility of the design, sandwich chimneys can be used both outside and indoors;
Unlike brick chimneys, the significantly smaller volume of sandwich structures allows them not to clutter up the interior space of the room;
Due to the fact that sandwich chimneys are made of stainless steel, they are resistant to factors generated during the combustion process, namely chemical and thermal aggression;
During the operation of sandwich chimneys, there is no damage to the internal layer of the structure under the influence of aggressive factors, and therefore it retains its performance characteristics for a long time;
The next advantage of sandwich chimneys is especially important for structures that use equipment with direct exhaust during operation. Thanks to effective thermal insulation, sandwich structures are reliably protected from condensation;
Due to the fact that the internal surface of the chimney is smooth, soot does not settle on it during its operation, which allows cleaning the chimney duct quite rarely;
Thanks to effective thermal insulation, the outer contour of the chimney does not heat up to critical temperatures, which can cause a fire in the combustible elements of the building. Taking this into account, we can talk about the high fire safety of the system;
Due to the convenience of the design, during the installation of which it becomes possible to make turns and bends of the chimney, by laying a sandwich chimney, you will be able to go around any obstacles in its path without resorting to dismantling the ceilings or removing roofing elements;
Thanks to the possibility of erecting a structure without an additional foundation, its installation becomes easier and cheaper.

Despite the significant number of advantages of sandwich chimneys, these structures also have certain disadvantages that also deserve attention.

Disadvantages of sandwich chimneys:

Possibility of loss of tightness of the structure in case of its long-term operation;
Violation of the integrity of the sandwich chimney in the event of constant sudden temperature changes;
Quite a high cost of construction;

Important! Despite the service life declared by the manufacturer to be no more than 10-15 years, in practice sandwich chimneys operate effectively for a longer time.

Main types of sandwich chimneys: brief description

It was previously noted that sandwich chimneys are multilayer structures made of ceramics or stainless steel. Currently, they are presented on the construction market in the form of ready-made elements, which are subsequently assembled into a single structure. Despite the fact that both types of construction are characterized by a similar installation method, each of them also has its own characteristics, which will be discussed below.

Stainless steel sandwich chimneys

The design of stainless steel chimneys includes an internal pipe, characterized by resistance to high temperatures, which is wrapped in non-flammable thermal insulation material. It is protected from external influences by another pipe called the outer loop and made of stainless steel or galvanized metal, the use of which is a budget option. It is important to note that the internal contour can be made of metal or ceramic, which is typical for combined chimneys.

Ceramic sandwich chimneys

The design of ceramic chimneys is represented by a pipe made of heat-resistant ceramics. The outside is wrapped with thermal insulating mats, and the inside is covered with high-strength glaze. This structure must be placed in an outer shell, for the manufacture of which expanded clay concrete and foam concrete blocks are used. The design features of ceramic chimneys, namely the presence of a heat-insulating layer, allow them not to heat up from the outside, which determines their absolute fire safety.

Important! Despite the fact that the design of ceramic and metal chimneys is generally similar, there are also differences, the main one of which is weight. The weight of a full-fledged ceramic chimney can reach a ton, while the weight of a stainless steel chimney does not exceed two hundred kilograms. In addition, an integral stage of installing a ceramic chimney is the arrangement of the foundation, while the installation of a stainless steel chimney is limited to the arrangement of unloading areas at each floor level.

The most current methods of connecting sandwich pipes for chimneys: brief description

There are several ways to connect sandwich pipes for chimneys. The most popular of them are: flange method, bayonet method, “cold bridge”, “condensate” and “smoke”.

The latter method of assembling a chimney completely guarantees that carbon monoxide will not penetrate inside the house or bathhouse. And using the “condensate” method, you can be sure that the condensate formed inside the chimney will flow freely down the walls of the pipe.

What must be observed during the installation of a chimney made of sandwich pipes?

The height of the chimney from the heating device to the tip is a fairly constant value and should be at least 5 m;
It is necessary to pay attention to the roof of neighboring buildings: the elevation of the chimney relative to neighboring buildings should not be more than 1.5 m;
If the chimney is elevated above the roof by 1.5 m or more, it needs additional fastening using braces;

In accordance with the recommendations of experts, the design of the chimney should include plugs equipped with a condensate drain, which is designed to remove condensate and inspect the chimney;
In the case of installing a roof made of flammable materials, the chimney design must include a spark arrester made of mesh with a cell of at least 5x5 mm;
During the installation of a sandwich chimney, it is unacceptable to narrow the diameter of the chimney, but it is possible to expand it. For example, when installing a sandwich chimney for a stove with a chimney outlet diameter of 115 mm, you can use pipes with a diameter of 120 mm, but the use of a chimney with a cross section of 110 mm is strictly prohibited;
Horizontal sections of the chimney should have a length of no more than 1 m;
The chimney elements must be mounted in such a way that their connection points do not coincide with the sections of the ceiling and roof passages;
The installation of bends and tees must be carried out in such a way that they do not bear the load from the weight of the chimney elements that are installed above it.

How to install a sandwich chimney: step-by-step guide

How to choose the dimensions of chimneys: we make the necessary calculations

Before you begin installing a sandwich chimney with your own hands, you need to know the following parameters:

The cross-sectional size of the chimney pipe;
The length of the chimney pipe.

The cross-sectional size of the pipe is determined in accordance with construction rules and regulations (SNiP). They are calculated as follows:

If the thermal output does not exceed 3.5 kW, the calculations are as follows: 0.14 m x 0.14 m;
If the thermal power is in the range from 3.5 kW to 5.2 kW, the cross-section should be characterized by the following parameters: 0.14 m x 0.2 m;
For thermal power values from 5.2 kW to 7 kW, cross-sectional dimensions 0.14 m x 0.27 m.

Important! As can be seen from previous calculations, the cross-sectional dimensions directly depend on the thermal power. After reviewing the above parameters, you will be able to select the most optimal cross-sectional dimensions of the pipes for the chimney. Having given preference to a round cross-section, you should know that its dimensions must be equivalent to those of a rectangular one.

The length of the chimney pipe is also calculated in accordance with building rules and regulations (SNiP):

SNiP 41-03-2001 states that the minimum height of pipes that trap smoke must be at least 500 cm;
Chimneys must be installed above the ridge of the house by at least 50 cm;
If the roof is made of flammable materials, the pipe must be removed from the ridge or parapet at a distance of 1 to 1.5 m;

Nuances that must be taken into account during the installation process

The installation of the chimney should start from the heating device, after which it gradually moves upward. To produce it according to all the rules, it is necessary to take into account the following nuances:

Chimneys must be characterized by the absence of ledges;
The temperature of the gases carried through the outlet pipe should not be higher than 500 degrees;
The maximum angle of pipe outlet should not exceed 30 degrees;
Sections of the pipe located at an angle must be free of roughness, and their cross-sectional area must be no less than that of the vertical ones;
It would not be superfluous to install a deflector, umbrella or other attachments that protect the chimney from precipitation, but they should not prevent the free exit of smoke from the chimney;

Important! The chimney must be installed in such a way that the gas pipeline, electrical wiring and other communications do not come into contact with it.

The chimney originates from the fireplace or stove. First of all, it is necessary to connect the pipe of the heating device to the first link of the chimney and close it with a plug so that the insulation protruding from it is not noticeable and steam does not escape from it;

The pipes are inserted into one another. To perform this manipulation, you need to carefully examine the pipe, after which you will notice that one of its ends is characterized by a smaller diameter. This end must be inserted into the next pipe;

Important! During the installation of the chimney, make sure that the pipe links are assembled in such a way that the condensate formed during their operation flows down unhindered.

It must be remembered that the sandwich chimney installation technology involves joining both the outer and inner pipes, which is often associated with some difficulties. In this regard, a simpler method for assembling sandwich pipes was developed, according to which it is necessary to extend the inner pipes by 15 cm and connect them, and then join the outer pipes;

Strengthening the formed joint. To carry out this manipulation, it is necessary to prepare a steel clamp and, wrapping it around the joint, tighten the clamp using bolts, nuts or wire;

The next stage involves applying a sealant to the pipe that retains its performance characteristics at temperatures up to 1000 degrees;

The sandwich chimney assembly is complete. Working according to the above principle, it is necessary to secure the tee, corner, umbrella and tip. Every 2 m of pipe, it is necessary to fasten the chimney to the wall using brackets. To reduce the load placed on the structure, the tee locations are also secured using brackets.

Important! A chimney, the installation of which was carried out by hand, requires the arrangement of a retreat. The setback is the space between the wall and the smoke duct, the value of which is calculated according to the table below.

If the retreat is located in the walls that cover it, then two openings with different levels, equipped with gratings, must be installed above the stove. The minimum cross-sectional area of each hole must be at least 150 square meters. cm. In the process of installing a closed setback, it is necessary to take into account that the floor in it is mounted from non-combustible materials and should be located 7 cm higher relative to the floor of the room.

Installation of a chimney in places of contact with the house

How to pass floors

The floors (ceiling) must be subjected to so-called cutting. In those places where the chimney comes into contact with the structural elements of the house, it is necessary to install a special chimney unit, which is a passage pipe or a box with a hole inside. It must be remembered that the size of the cut should be 7 cm greater than the thickness of the passable floor. The cutting is designed to protect the flammable structure from fire.

Important! Refuse to rigidly connect the cutting to the structure. The pipe in the branch pipe must be characterized by the absence of joints.

In the ceiling, prepare a hole for the chimney and mark it with a marker, double-checking the accuracy of your calculations several times. After making sure that the pipe is correctly positioned in the ceiling and checking the dimensions of the pipe with the marked marks, proceed to cutting.

Experts recommend covering the pipe from the inside and outside with a foil-coated basalt mat with fire-resistant mastic. The hole itself must also be insulated with mineral wool insulation at the points of contact with the pipe.

Install the flow pipe into the prepared hole and check the verticality of the installed pipe. If it is not strictly vertical, it must be leveled.

The roof, like the ceiling, is passed through a special link, which at this stage is called “roof cutting”. To choose the right one, you need to know the angle of the roof.

It is necessary to prepare a hole in the roof for the chimney, which is also done using a marker and is carefully checked. It is necessary to cut a hole from the inside of the roof.

A galvanized metal sheet with a hole for the pipe is placed on the inside of the roof, after which the pipe is removed and the sheet is secured on the inside. A “roof trim” is installed on top of the roof. If the need arises, a metal roof cutting sheet is placed under the edge of the roof or ridge. Next, you need to install the required number of links to the required height of the chimney and secure the umbrella.

To get a more complete, from a practical point of view, answer to the question: “How to make a sandwich chimney?”, Watch the video below.

Sandwich chimneys video