In recent years, more and more chimneys are made from sandwich pipes. The point is a relatively low price, long service life, and quite attractive appearance. It is also important that independent installation of a sandwich chimney is possible. This is not a very simple matter - there are many nuances, but you can do it yourself, without the involvement of specialists.
What is a sandwich pipe and what are they?
The sandwich pipe was named so for its multi-layer nature: there are two layers of metal, between which there is insulation. This structure solves many of the problems that were inherent in a simple chimney made of a metal pipe. Firstly, the insulation layer does not allow the outer metal casing to heat up to critical temperatures, and hard radiation does not emit from the pipe. More comfortable conditions are created indoors. Secondly, the same insulation significantly reduces the amount of condensation that forms when the pipe is brought outside. Thirdly, since the outer casing is no longer at such a high temperature, it is easier to make the chimney pass through the roof or wall.
A sandwich pipe is two metal cylinders, the space between which is filled with insulation.
What materials are they made from?
Sandwich pipes are made of galvanized or stainless steel. Galvanized sandwich pipes for chimneys are rarely used. Perhaps for the removal of combustion products from a low-power wall-mounted gas boiler or gas water heater. Can be used for insulated ventilation. They are unsuitable for more serious heating devices - at high temperatures, zinc burns out, steel quickly rusts, and the chimney becomes unusable.
Sandwich pipes for high-temperature flue gases are made of stainless steel. Moreover, stainless steel is used in different grades - from alloys with a small content of alloying metals to highly alloyed heat-resistant ones. The thickness of the metal can also be different - from 0.5 to 1 mm, as well as the thickness of the insulation - 30 mm, 50 mm and 100 mm. It is clear that the scope of application will be different, and so will the price.
The main grades of steel that are used in the production of sandwich pipes for chimneys, their purpose and main characteristics are summarized in the table.
| Stainless steel grade | Main characteristics | Application area |
|---|---|---|
| AISI 430 | It has sufficient resistance to atmospheric influences, but does not tolerate high temperatures well | Used for outer casings of sandwich pipes |
| AISI 439 | Contains titanium, which increases resistance to elevated temperatures and aggressive environments. | Suitable for gas boilers, low-power solid fuel units (up to 30 kW) |
| AISI 316 | Alloying additives - nickel and molybdenum - provide high resistance to acids and increased heat resistance. | Optimal for gas boilers of any type. |
| AISI 304 | Cheaper version of AISI 316 with fewer alloying additives | Economy option for gas boilers of medium and low power |
| AISI 316I, AISI 321 | Withstands temperatures up to 850°C | Can be used for heating solid fuel stoves |
| AISI 310S | Increased heat resistance - up to 1000°C (and price) | For sauna and pyrolysis solid fuel stoves |
As is clear from the table, different grades of stainless steel have different purposes. Cheaper alloys are used for the outer casing, more heat-resistant and expensive ones for the internal casing. This is necessary to reduce the cost of products, and high resistance to temperatures outside the chimney is not needed. There are even more budget options - the outer casing is made of galvanized steel. Externally, these products are inferior to stainless steel, but serve normally (with normal insulation and its thickness).
Insulation and its thickness
There is insulation between two layers of metal. Most often this is stone wool. The thickness of the insulation varies from 30 to 100 mm:
- With 30 mm thick insulation, the flue gas temperature should not exceed 250°C. Such temperatures are produced only by gas boilers of small and medium power.
- A 50 mm insulation layer can withstand temperatures up to 400°C. Scope of application - any gas and liquid fuel boilers, wood-burning, provided that the chimney is vented to the street (through the wall).
- A 100 mm layer of stone wool can withstand temperatures up to 850°C. Such a sandwich chimney can be installed on any type of solid fuel boiler, in fireplaces and hearths.
In addition to the thickness of the insulation, you need to pay attention to its brand, or rather, to the temperature range in which it can operate. Not every stone wool can withstand heating up to 850°C, but only some special brands. If you need a chimney for a solid fuel boiler, you will also have to take into account the heat resistance of the insulation.
Connection types
Sandwich chimney elements can be connected to each other in two ways: with sockets and corrugated edges. A socket connection requires a slightly wider chamfer on one side. With this design, a high degree of chimney tightness is achieved. This type of sandwich pipe is well suited for gas boilers, where it is important to prevent leakage. There is also a minus: installation requires high precision.
The corrugated edge of the sandwich allows you to assemble the chimney without problems. The disadvantage of this solution is that to ensure tightness, a significant amount of high-temperature sealant is required, and it costs a lot.
It is also worth paying attention to the longitudinal seam. It can be welded or folded. If the seam is welded, it must be made in an argon protective environment (so that alloyed metals do not burn out). This type of connection is necessary for solid fuel boilers, sauna stoves and fireplaces. For all others, you can use a seam connection.
Installation methods
There are two ways to vent the chimney outside. The first is to run the pipe through the wall, and then raise it along the outer wall to the required level. The second is up, through the ceiling and roof. Both are imperfect.
If the chimney is outdoors, condensation actively forms in it due to temperature changes. Therefore, a tee with a condensate collector (glass) and a cleaning hole must be installed in the lower part of the chimney. This unit allows you to maintain the chimney without much difficulty: the glass is unscrewed and the condensate is drained. Also, soot periodically gets knocked off without any problems - you can run a special chimney brush through the cleaning hole.
If the chimney will be discharged through the roof, several passage units will be needed - according to the number of ceilings. If the house is one-story, you will need one passage through the ceiling, and a second through the roof. You will also need a master flash or an apron for a round galvanized pipe.
Installation of a sandwich chimney on the street requires only one passage unit - through the wall. But it will be necessary to attach it to the wall every 1.5-2 meters. If the walls of the building are flammable (wooden house or frame), the walls must be protected with a non-combustible screen.
By smoke or condensation
As mentioned above, one side of the sandwich pipe is slightly wider, the other is slightly narrower. Due to this difference in diameter, the modules are connected to one another. If the wider end is turned upward (in the figure on the right), the assembly is called “condensate”. With this installation method, drops of condensate flow down unhindered. The disadvantage of this method is that if the joints are not properly sealed, smoke can leak into microcracks. This type of sandwich chimney installation is used when the pipe is routed through a wall. This is where the free drainage of condensate is required, and small smoke leaks are not scary - they are not critical on the street.
If the narrower edge is turned upward, the second element is put on top of it with the wider part. This type of assembly is called “by smoke” (in the picture on the left). In this case, condensate flowing down the wall may leak through a joint that is not sealed well enough. But the smoke passes freely. This type of assembly is used if the pipe goes indoors (out through the roof). Condensation flowing through the pipe, of course, spoils the appearance, but it is not as dangerous as flue gases leaking into the room. Moreover, if the joints are well sealed, condensation will not leak out.
In order for the connection of the sandwich chimney modules to be reliable, each of them is usually coated with a heat-resistant sealant and then tightened with a clamp.
Options
Sandwich chimneys are good because they have a modular structure, which allows you to assemble any configuration, with any parameters. Before you go to the store, you need to know the required diameter of the chimney, the height of the pipe and those additional elements that will be needed.
Chimney diameter
When choosing the diameter of a sandwich pipe, a simple rule applies: it cannot be less than the diameter of the boiler outlet pipe. If your outlet pipe is 120 mm, then the internal diameter of the sandwich should be the same or larger. It may be wider, but definitely not smaller, and the narrowing cannot be done along the entire length of the chimney. If the chimney is slightly wider than the pipe, an adapter is purchased, which is placed directly at the boiler outlet, and then the working size comes next.
If you don’t have a boiler yet, but you know its power, you can choose a chimney based on these data:
- boiler power up to 3.5 kW - internal diameter of the sandwich - 80 mm;
- from 3.5 kW to 5.2 kW - at least 95 mm;
- more than 5.2 kW - 110 mm and more.
But it’s better to buy (or at least choose) a boiler, and then decide on the chimney, because many manufacturers insure themselves by making the outlet pipes wider to improve draft.
Pipe height
The height of the chimney above the roof surface depends on the location of its outlet, but its minimum height should be 5 m. That is, if the height of the house is small, in any case, install the pipe to a height of 5 meters. If the height of the house is above 5 m, then the pipe should rise above the roofing material to the following height:
- Should rise 50 cm above the ridge if it comes out at a distance of less than 150 cm from it.
- If the distance from the ridge to the pipe is more than 300 cm, then the pipe may be lower than the ridge level, but the angle should be no more than 10° (see figure).
- If the chimney exits at a distance of 150 to 300 cm from the ridge, its height can be at the same level as the ridge element or higher.
Under such conditions, normal traction is ensured. The smoke will go away normally regardless of weather conditions. To prevent leaves from getting into the chimney, they install special umbrellas, weather vanes, and in windy places - deflectors, which further improve draft.
If it is not possible to bring the pipe to such a height, they install a smoke exhauster - a forced draft is obtained. A fan will not be needed all the time, but in some conditions, when natural draft is not enough, forced exhaust saves the situation.
Installation of a sandwich chimney through a wall
When venting a chimney through a wall, there are two ways. The first option (pictured on the left) is to raise it in the room closer to the ceiling and take it out there. The second is to draw a conclusion at the level of the smoke pipe from the boiler. In this case, almost the entire chimney ends up on the street.
The second option is preferable - it has only one knee, which means, under equal conditions, the traction will be better. Also, with this structure there is less chance of soot plugs forming.
If the outlet of the smoke pipe is located not at the back of the stove, but at the top, the installation diagram changes slightly - a 90° elbow is added, then a straight section for passing through the wall, and then the same as in other diagrams.
The stove itself is placed on a non-flammable base, and the wall behind the stove is covered with a non-flammable screen. The easiest way is to fix a sheet of metal to the wall. It can be mounted on ceramic insulators 2.5-3 cm in height. There will be a layer of air between the sheet of metal and the wall, so the wall will be safe. The second option is to place a thermal insulation material under the metal - for example, mineral wool cardboard. Another option is an asbestos sheet (as in the photo).
A hole is made in the wall. Its dimensions are determined by SNiP - the distance from the pipe to non-combustible walls must be at least 250 mm on all sides, and to combustible walls - 450 mm. It turns out to be a solid hole, especially if we talk about walls made of flammable materials. There is one way to reduce the size of the opening for the passage of the sandwich: make the dimensions according to the standards of non-combustible walls and sheathe the opening with non-combustible material.
The opening can be round or square, as long as fire safety standards are met. Square holes are easier to make and cover, which is why they are made more often.
A passage unit is inserted into this hole - a box made of non-combustible material. The sandwich chimney pipe is inserted into it and fixed in the center. All gaps are filled with heat-resistant insulation, the hole is closed on both sides with non-combustible material. This is usually a sheet of metal.
One important point: the chimney must be designed so that there is no junction of two pipes inside the wall. All joints must be visible and serviceable.
Next, you need to make or install a ready-made support bracket that will support the entire weight of the pipe. The design may differ in details, but the main idea is the same - a support platform, which, with the help of stops, transfers weight to the wall.
Homemade support platform for an external sandwich chimney from corners 50*50 mm and 40*40 mm
A similar structure can be welded from a profile pipe of small cross-section 25*25 mm or 25*40 mm.
As you can see, a tee is connected to the pipe that goes through the wall. At the bottom there is a removable glass in which condensation accumulates. Some models have a fitting at the bottom with a small tap. This is even more convenient - you don’t need to remove the glass, you can connect a hose to the fitting, drain it into some container (it is very toxic, so there is no need to drain it near the house) and drain it by simply turning the tap.
Next, the tube is brought to the required level. Since in this case the distance to the ridge will clearly be more than 3 m, it is possible that the height of the chimney should be slightly lower than the ridge - no lower than 10° relative to the horizontal line drawn from the level of the ridge.
But since this house is located in a low area, to ensure traction, the pipe was raised even higher than the ridge. It was attached to the wall with stainless steel clamps, in increments of a little more than a meter. The roof is equipped with guy wires made of steel rods with a diameter of 6 mm. To install guy wires, there are special clamps “with ears” to which the guy wires are attached.
Attaching guy wires to a chimney from sandwich tubes
Another important point that many people forget: at the place where the pipe is installed, a snow retention section must be installed on the roof, otherwise in the spring the pipe may be blown away by snow (if the pipe is not routed towards the gable, as in the photo).
How to install a chimney through the roof
When venting a chimney from sandwich pipes through the roof, it is necessary to take into account the location of the floor beams and rafters on the roof. It is necessary to arrange it so that the pipe passes between these elements. The minimum distance from the outer wall of the pipe to the combustible element must be at least 13 cm, and this is provided that the combustible element is protected by insulation. To meet this requirement, the pipe often has to be displaced. This is done using two 45° angles.
Please note that the installation of a sandwich chimney from a solid fuel boiler begins with a metal pipe without insulation. In the photo above it is black. After this, an adapter is placed on the sandwich, and a chimney with insulation enters the passage unit.
A hole is cut in the ceiling that meets fire standards - 250 mm from the edge of the pipe, if the ceiling is protected by thermal insulation material. Having cut a hole, its edges are covered with non-flammable heat-insulating material. Minerite is best suited for this (it is nailed or secured with wood screws).
The gray material around the perimeter of the hole is mineralite
The sandwich chimney pipe is inserted into the resulting box. It should be directed strictly vertically, without the slightest deviation. You can’t fix it rigidly, you can only give it direction by installing several bars that will hold it, but it can move up/down without difficulty. This is necessary, since when heated its length increases significantly.
The remaining space is filled with basalt wool (check the temperature range). Another option is to pour expanded clay or granulated foam glass. Previously, sand was still poured in, but sooner or later, it all spilled out through the cracks, so now this option is unpopular. On the front side, all this “beauty” is covered with a stainless steel sheet, under which a non-combustible material is placed (between it and the ceiling). Previously, it was an asbestos sheet, but since asbestos is recognized as a carcinogen, mineral wool cardboard began to be used.
There is another option. Trim the edges of the hole with mineral wool, and then insert the finished stainless steel ceiling-passage assembly. It immediately contains both a box and a decorative stainless screen.
Having brought the pipe into the attic, they make a hole in the roofing pie. All films in the passage area (vapor barrier and waterproofing) are cut crosswise. The resulting triangles are wrapped and secured with staples from a stapler. This way the damage is minimal. The exposed sheathing is cut so that it is at least 13 cm from the pipe.
How to bring a chimney through the roof - passage of the ceiling and roof
In the right photo above, the passage through the roof is incorrect - the distance between the pipe and the boards is too small. In a good way, you need to cut them according to the standard, and cover them with the same mineralite. The result should be something similar to the following photo.
Master flash for a sandwich chimney - a rubber cap with a flexible “skirt”
The joint between rubber and pipe is sealed with heat-resistant sealant. The roof surface under the “skirt” is also coated with sealant.
Please note that each connection of the sandwich modules is tightened with a clamp. This is also true for the internal chimney.
In this article we will talk about how to correctly calculate the dimensions and how to assemble a sandwich chimney with your own hands. All figures given in the article are based on the requirements of building codes that relate to heating, ventilation and air conditioning.
A chimney is necessary for houses if they are heated by a fireplace, stove or gas boiler. Its main task is to remove combustion products outside. In this case, all safety standards must be observed.
Due to the simplicity of its design, assembling a sandwich chimney does not seem to be a difficult task. And thanks to its special design, the chimney does not require frequent maintenance, and its service life is quite long.
We calculate the correct dimensions for the chimney
The exact installation diagram of a sandwich chimney depends on the overall dimensions of the pipe required for normal smoke exhaust. To do this, it is important to calculate the cross-sectional dimensions and length of the pipe.
Determining the dimensions of the pipe section
- 0.14*0.14 m with boiler thermal power up to 3.5 kW;
- 0.14*0.20 m with power from 3.5 to 5.2 kW;
- 0.14*0.27 m with power from 5.2 to 7 kW.
That is, the cross-sectional dimensions depend directly on the thermal power of the heating equipment. The above parameters will help you choose the section size yourself. If a round pipe is used as a chimney, then its area should be equal to the cross-sectional area of a rectangular pipe for a certain boiler power.
All sandwich chimney elements must have a certain length.
- in accordance with SNiP 41-01-2003, the height of the smoke trap pipe should not be less than 500 cm;
- the chimney pipe is installed above the ridge by 50 cm or more;
- if the roof of the house is made of flammable material, it must be at least 1 m;
- if there are extensions whose roof height is higher than the main building, the chimney pipe is installed above this extension.
The influence of the pipe location on its height:
- For a flat roof, the pipe should be installed 50 cm higher from the roof surface.
- If the chimney pipe is located close to the ridge (up to 150 cm), then its height should be 50 cm above the ridge.
- If the pipe is located at a distance of up to 3 m from the ridge, then it can be brought out flush with the ridge, the main thing is to understand how to assemble a chimney from sandwich pipes.
- If the chimney is located far from the ridge (more than 3 m), then the end of the pipe can be brought below its level (the line drawn from the ridge to the end of the chimney should have an angle to the horizon of up to 10 degrees).
Based on the instructions above, you already know how to properly assemble a sandwich chimney.
Important aspects of chimney installation
Before installing the sandwich, it is necessary to check some aspects of the heating system.
It is important to know the following:
- chimney pipes should not have ledges;
- the temperature of the gases rising through the pipe should not be more than 500 degrees (read also: " ");
- pipes can be moved to the side at an angle of 30 degrees;
- inclined sections of the chimney should not have any roughness. The cross section must have an area not less than the vertical one.
In addition, it is important to protect the chimney itself from precipitation. The function of such protection is performed by a deflector, umbrella and other similar attachments. It is also important to remember that it is strictly forbidden to lay electrical wiring or other communications in close proximity to the chimney.
Sandwich chimneys: instructions
- Attaching a sandwich chimney starts from the fireplace or stove. The first link of the pipe is connected to the outlet pipe of the heating device. The gaps are closed with a plug. Read also: "".
- The pipes are inserted into one another. You will immediately notice how this needs to be done, since one edge of the pipe is always narrower than the other. This method of collecting pipes allows the resulting condensate to fall down unhindered.
- It is important not to forget that not only the outer but also the inner pipe must be joined. Connecting both pipes at the same time is quite a difficult task. In order to carry out this procedure, it is enough to simply release the inner pipes outwards with an overhang of 15 cm. This allows you to easily connect them. And only after that the external pipes are joined.
- The resulting joint must be strengthened. To do this, take a galvanized clamp, which is wrapped around the joint. Then we tighten the clamp with nuts, bolts or wire. A layer of sealant that is resistant to high temperatures is applied to the pipe (stability margin is up to 1000 degrees).
The chimney sandwich is almost assembled. Next, using the same principle, they begin to attach the tee, corners, tip and umbrella. Every 2 meters, sandwich ferrum chimneys are attached to the wall. must be quite reliable; brackets are used for this. The tee is attached to the wall with support brackets. This allows you to reduce the load on the chimney riser. If necessary, you can install horizontal chimney links, but then their length should not be more than 1 meter.
During installation, it is important not to forget to remove the film that covers the sandwich pipes.
What is a derogation
Like any other chimney, our design needs so-called setbacks. This term should be understood as the space formed between the wall and the smoke exhaust duct. The size of the setback is taken in accordance with building codes.
Table - Sandwich chimney sizes
If the setback is placed in the walls, then two holes should be arranged at different levels. Each such hole must be protected with a mesh and have a cross-section of at least 150 sq.cm. In a closed retreat, the floor is made of non-combustible materials. At the same time, it is raised 7 cm above the level of the main floor.
Passage through floors
Overlappings are carried out using the so-called cutting. At the point where the chimney comes into contact with the structure of the house, it is necessary to install a special link. Often this is a box with a hole or a pass-through pipe.
The cutting size is made 7 cm larger than the thickness of the ceiling. Its main task is to protect wooden and, therefore, flammable structures from fire (more details: ""). In this case, the cutting does not need to be rigidly connected to the structure of the house. The pipe in the pipe is selected so that it does not have joints.
Despite the huge selection of materials for the construction of chimneys, the most widely used today are double-circuit steel pipes, popularly called “sandwich”.
The sandwich type chimney is a two-layer structure. Between two metal pipes of different diameters there is a layer of heat-insulating material, which simultaneously serves as insulation and insulation.
Thanks to the British, all structures that consist of more than three layers are called “sandwiches”. And, of course, there is a chimney with a similar name, where between the two circuits there is a thermal insulation layer (mainly made of basalt-based materials).
Thanks to this, combustion products are removed from the combustion chamber as efficiently as possible, since:
- internal surfaces are resistant to condensing moisture and high temperatures;
- the thermal insulation layer prevents overheating of the external circuit;
- excellent traction is achieved;
- Design features do not allow moisture to enter the thermal insulator.
The interior of the chimney is made of stainless steel, which is known to be resistant to rust. As for the external, it is often made from galvanized steel, which is less durable, but costs less. Therefore, you will have to choose between quality (read: stainless steel) and economy (galvanized).
In addition to the chimney itself, during installation you will need:
- a special “adapter” for passing through the roof;
- brackets for fixing pipes;
- platform for unloading – it will allow you to evenly distribute the weight and relieve the base from the load;
- audit with a window for cleaning;
- clamps for fastening structural elements;
- adapters;
- elbow 90 or 45 degrees (to change the direction of the chimney);
- adapters.
Note! The upper part of the pipe can be decorated with a cone or other elements - a fungus, a spark absorber, a woppler, a weather vane, and so on.
The sandwich chimney provides excellent thermal insulation, so it can even be installed outside the house. But it will function much better if you install it in the house, as close as possible to the heat source (this minimizes heat loss).
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.
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.
Advantages and disadvantages of sandwich pipes
In industrial conditions, stainless steel products are used for the inner layer of the sandwich, and zinc-coated steel pipes are used for the outer layer. In this case, the inner contour is covered with thermal insulation and placed inside the outer cylinder. As a result, such a structure functions quite efficiently and efficiently.
Installing a chimney made from sandwich products does not take much time and effort - all the work can be completed in a day. Below we present a number of advantages and disadvantages of such pipes.
Among the advantages of such structures are:
- multitasking - such pipes can be used in buildings made of any materials;
- occupy a minimum of space;
- ease of transportation;
- Even a beginner in construction can install sandwich pipes, as it is very simple and quick;
- laconic and pleasant appearance;
- fire safety - this is one of the best options for chimneys in this regard;
- the existing roof truss system does not create any obstacles to the installation of a sandwich pipe;
- due to the presence of several layers, much less soot accumulates in such a pipe and almost no condensation forms, so cleaning it is required much less frequently;
- The sandwich pipe is capable of fully protecting residents from the influence of toxic combustion products.
But such designs have very few disadvantages, although they still exist:
- the price of a sandwich pipe is quite significant;
- The optimal service life of such products is only about 15 years.
If you want to make a sandwich pipe with your own hands, then such a chimney will cost you much less than, say, one made of brick. This will result in a completely reliable chimney, and there should be no difficulties with installation and assembly.
- The thermal insulation layer prevents the outer pipe from heating to a critical temperature.
- Compact and versatile in use.
- The smooth surface of the inner casing increases the chimney draft.
- Low price compared to ceramic material.
- Operating temperature up to 850 degrees (for single-circuit pipes, for comparison, 500).
- Easy to assemble.
- The fire safety of the home increases.
- Easy maintenance compared to a solid pipe chimney (less soot accumulation).
- Does not create additional noise when drafting smoke.
Stainless steel chimneys have the following qualities:
- Easy to install.
- Compact.
- Universal. There are exits both upstairs and through the wall.
- Multi-layered. Best protection against condensation.
- Wear-resistant and not susceptible to aggressive influences. Resistant to even the most aggressive chemicals.
- The most fireproof of all those currently on the market.
The use of metal pipes to remove fuel combustion products has been practiced since ancient times. This is due to the fact that their shape is optimal for the flow of hot gases; less soot buildup forms on the smooth inner surface. In addition, compared to brickwork, installation work is significantly simplified.
Chimneys made of metal pipes are exposed to aggressive hot gases. This leads to the development of corrosion processes and, ultimately, to burnout of the exhaust system. The use of corrosion-resistant metal alloys for its manufacture solves the problem only partially, while the following negative factors remain:
- Reduced draft in the chimney due to the high thermal conductivity of the metal. This is due to the rapid cooling of hot gases in the external parts of the structure in contact with the environment.
- Condensation of moisture vapor on the internal surfaces of pipes due to temperature differences. This leads to a decrease in their permeability and contributes to the formation of soot deposits.
- A hot metal chimney poses a fire hazard. Elements of a building structure may catch fire, touching the surface of which results in a burn for a person.
When installing a standard furnace or boiler room and a boiler operating on solid, liquid or gas fuel, a chimney installation is required. The smoke removal system serves to remove flue gases into the atmosphere and requires general rules for its installation as for a boiler, stove or fireplace.
Therefore, all issues related to installation work must be resolved at the design stage. Having decided to carry out the installation yourself, it is important for the owner of a country house to additionally familiarize himself with the main rules and useful tips regarding the performance of such work.
Before you properly make a chimney for a gas boiler, you must first pay attention to the following factors:
- correct calculation of all parameters, including the size of installed pipes;
- determining the correct pipe length; determining the location of the chimney;
- familiarization with the basic rules for assembling a structure;
- features of the passage of floors, the creation of insulation for the pipe and the exit of the chimney pipe to the roof.
Before installing a chimney, it is necessary to correctly determine the dimensions of the structure. This includes not only the length of the chimney, but also the cross-sectional diameter of the chimney pipe. To make the most correct choice, it is enough to familiarize yourself with the regulatory requirements of SNiP. It is recommended to select the diameter according to the thermal power of the furnace or boiler.
- the diameter of the pipe should not be less than the diameter of the boiler outlet;
- if the thermal power indicator is less than three and a half kilowatts, the optimal pipe cross-section should be 14 centimeters;
- if the thermal power indicator varies between 3.5-5.5 kilowatts, the diameter must be increased to twenty centimeters;
- if the thermal power indicator is 5.5-7.5 kilowatts, it is necessary to install a chimney with a diameter of 27 centimeters.
In this case, the length of the chimney must be determined according to the following rules:
- the minimum height that will make it possible to create the required thrust is 5 meters from the combustion chamber to the top;
- if the roof is flat, then the chimney must rise above the roof by at least 0.5 meters;
- do not forget to pay attention to the roofing material used during construction work. If the roof is made of flammable roofing material, the height of the pipe above the ridge should be one meter. The best option is one and a half meters.
Installation diagrams for chimney sections
If you prefer to install the structure externally, you need to attach a pipe to the wall every meter. This is possible thanks to special brackets that prevent collapse under strong wind influence. It is also important to pay attention to the distance from the wall at which the brackets are mounted on the chimney of the boiler room.
1, 4.Brackets 2.Tee 3.Plug 5.Insulator 6.Pipe
- Triplets item 2 should be selected locally in accordance with the area of the pipe of the device connected to the chimney.
Bracket for attaching pipes to the wall of a building
1. Console 2. Angle 3. Half-clamp 4,5,6 Bolt, Nut, Washer
- It is also important to pay attention to the distance from the wall at which the brackets are mounted on the chimney.
Bracket for fastening the base of the chimney pipe
1. Console 2. Strut 3. Angle 4. Hairpin 5. Pipe 6. Bottom
Chimney passage through the wall of a building
- The gaps between the bracket pipe and the tee are sealed with 30 mm asbestos cord.
Chimney insulator for penetration through the wall of a building
An example of a sleeve (piece of pipe) when passing through a wall made of non-combustible materials.
The next option is installation inside the building. As a rule, the chimney is located on the outside of the building, but it can be installed right at home, although for this you will have to create passage units through the ceiling and roof. Here you will need to pay special attention to the places where the pipe passes through the ceiling and what your ceilings (floor, ceiling) are made of, whether they are flammable or non-combustible materials.
1. Sandbox 2. Tee 3. Plug 4. Support structure 5. Apron 6. Pipe
Chimney insulator when passing through ceilings
- After installation, the insulator must be filled with non-flammable filler, for example sand.
Attaching the insulator to the ceiling
- The orientation of the supporting structure is taken depending on the supporting beams.
The assembly of the chimney through the combustible ceiling
The assembly of the chimney through the fireproof ceiling
The passage of the chimney through the roof (roof)
Support structure for roof penetration
- The size of the supporting structure is taken depending on the melting between the rafters.
The final chimney installation scheme is determined by the owner of the house at his own discretion.
Features of determining the height of the pipe based on its location
To determine this parameter, it is necessary to take into account the location of the chimney in relation to the ridge structure; a diagram of the wind support zone will help with this.
In this case, the building owner should also not have difficulties:
- if the distance between the pipe and the ridge is up to one and a half meters, the upper part of the pipe must be raised above the ridge by 50 centimeters;
- if the chimney is located from one and a half meters to three meters from the ridge, its height can be at the same level as the ridge;
- if the distance between the chimney and the ridge is more than three meters, the height can be fixed at the level of the contour located at an angle of ten degrees from the horizon of the roof ridge.
Note. Before making a chimney, you must also pay attention to the presence of buildings nearby. If their height is greater than that of a residential building, the top point of the chimney must exceed the top point of the extension roof by one meter. Thus, the constructed chimney will always be operated with maximum safety.
Assembling the pipe structure
One sandwich segment is one meter high. During the installation process, one pipe is installed into another (into a socket). When installing a sandwich chimney with your own hands, you must adhere to a strict sequence of work. So, for example, installation begins from below the stove, and then smoothly goes up. During installation, joints are always formed on the outside of the pipes. They must be covered with a special plug that covers the insulation. We install individual segments one meter high one inside the other.
Note! Before installing the chimney correctly, you must remember that the pipe always has one narrowed end. It must be installed in the next pipe. Each link is assembled in such a way that the condensate released during operation cannot be retained. It should flow down.
The joining must be done so that the inner pipe and the outer casing have a tight connection with each other. Without possessing specialized skills, it may initially seem that this work is problematic. You can simplify the task with one simple trick. Before installing the inner pipe, you need to extend it 15 centimeters, and then insert one pipe into the other. Only after this can you begin to connect the outer casings.
Note. Sometimes manufacturers pack their own products in special plastic film. Before you start installing chimneys for gas boilers, you must get rid of it.
When assembling the structure, it is important to strengthen all joints with special clamps. Usually they are included in the basic kit, but if you notice that they are not there, you will have to purchase additionally. Place clamps and tighten them around the joint; it is important to pre-treat the joints themselves with a special sealant so that the structural layer of the chimney is not damaged by heating. On sale you can always find special compounds that are used for furnace equipment.
Chimney pipe design
Before assembling the chimney, do not panic about possible difficulties. To correctly assemble the structure, you must remember that this is just a product, the assembly of which is made of individual segments. Each of them contains a pipe, inside of which there is another one, but with a smaller diameter.
Between each pipe there is a special thermal insulation layer. Its type is selected depending on the scope of application and technical features of the furnace and boiler.
The outer layer is a casing made of stainless steel. The inner layer is also made of stainless steel, but inside it is coated with a special anti-corrosion coating.
There are other varieties. For example, you can not only assemble a chimney from stainless steel, but also purchase products made from copper, brass or ceramics. In this case, stainless steel is the highest priority option, since all other varieties are characterized by high cost.
For example, if you assemble a chimney from simple ordinary steel, its service life will be limited by its wall thickness, since soot from flue gases contains sulfur, which upon contact with moisture turns into acid; it will gradually turn such a chimney into a sieve.
On the good side, we can also note asbestos-cement pipes; they are connected into a socket and are durable, but they are relatively heavy, fragile and, in my opinion, they have a temperature limit.
Thus, experts recommend installing a chimney made of sandwich pipes, where each part is made of steel. Manufacturers prefer to install insulation (mainly basalt) between the pipes, which will have a positive effect on the operation of the pipe.
The use of this design allows you to take advantage of a number of advantages. Firstly, basalt insulation does not collapse under the influence of temperature changes. Secondly, the product is characterized by increased resistance to chemical and physical stress. In terms of thermal insulation benefits, this material is one of the most effective. Different manufacturers prefer to install insulation with different thicknesses.
The minimum indicator is 26 millimeters, the maximum is 60. Such chimney pipes help prevent the penetration of cold into the premises when the stove is not in use.
Conclusion
In itself, installing a chimney from sandwich pipes is not a difficult job. It is quite possible to build such a structure yourself. The main advantage of using a stainless steel chimney is that there is no need to use bulky equipment to carry out the work. During the installation process, it is necessary to correctly select the height of the structure as a whole and the height from the roof of the building.
A correctly assembled chimney will always delight you with trouble-free and high-quality work over a long period of time. But if you do not understand all the intricacies of chimney installation, it is best to seek help from specialized specialists.
Many future owners of country houses would like to have their own cozy home. Installation of a stove or fireplace necessarily requires the installation of a chimney pipe. The installation of a chimney is carried out at the time of construction and erection of walls, however, there are cases that customers have already built a house, but forgot to think about such things in advance. Therefore, today’s article will be useful not only to those who are still at the construction stage, but also to those who have a desire to build a small fireplace after the construction of the house. We will try to answer in detail in this article how to do this and what to pay attention to.
Preparatory work
Before proceeding with installation, it is necessary to clarify several basic factors. When selecting a channel, you need to take into account the height of the building, the diameter of the future channel, and others. Give special attention to the installation site and location of the heating equipment. Installation of a sandwich chimney, like any other, can be done in two main ways:
- Internal.
- External.
For example, when installed internally, the installation of a sandwich chimney is carried out directly in the heated room, and in this case additional sealing is not required. But, there is a nuance, if the attic space is not heated, in this case, it would be useful to additionally insulate the pipe during installation and carry out a seal to prevent exhaust gases from entering the rooms with the ensuing consequences.
In addition, at the initial stage, think about what to do with those materials, walls, next to which, in contact, the chimney will pass. Surfaces must be treated with special fire retardants.
As for external systems, the assembly of the external sandwich chimney must be carried out taking into account the mandatory insulation. These types are much safer, since they immediately remove the pipe to the outside during installation, reducing the likelihood of exhaust gases entering the premises.
Which type and shape should I choose? Here it is worth giving preference not only to aesthetic indicators, but also to functional ones. Keep in mind that it is easy to fix or fasten a square chimney, it is quite easy to use and does not require special skills during installation. But the main disadvantage of such a system is the accumulation of condensation and other unnecessary dirt and dust inside.
Round elements in this part are much preferable, given their shape; they retain much less not only a variety of debris that can get in from gusts of wind, but also form less condensation, naturally taking into account proper insulation. The only thing is that such systems are difficult to install and you will need skill.
In addition, do not forget to prepare the necessary tools for installation in advance. So, the tools needed to install a chimney:
- Drill, grinder.
- Jigsaw, screwdriver.
- Hammer.
- Screwdrivers.
- Protective ammunition.
- Spatula and chisel.
Main stages of installation
To install a chimney with your own hands, you need step-by-step instructions. Below is a sample work plan that is recommended to be followed. So:
- First of all, calculate the channel and adjust the dimensions “on the ground”.
- We install the formed stainless steel chimney pipe with our own hands.
- We connect the system, that is, we install the source (boiler, stove) and capacitor. It is also recommended at the time of installing a stainless steel chimney or installing a chimney made of sandwich panels, installing a condensate receiver and drain.
- Checking the system and installing the “umbrella” (head).
The peculiarity of fastening for chimneys involves the use of fastening elements, regardless of the type of system, every meter and a half. Taking into account the design of the chimney, carry out insulation and sealing work. When thermally insulating especially iron pipes, it is recommended to use a method that has been proven for centuries, namely clay. All modern methods cannot guarantee one hundred percent protection, so pay attention to this.
Calculation of chimney components
Installation of a chimney must take place after mandatory calculation of all elements, taking into account some rules that are fundamental. So, the necessary list of rules:
- If a flat roof of the building is provided, the ridge of the pipe should extend no less than 0.5 meters.
- For pitched roofs, the exit of the “umbrella” must be at least 1.5 meters and at the same level as the top ridge.
- When arranging a roof made of flammable elements, any pipe must rise at least 1.5 meters.
- In places of joints and passages through ceilings, it is necessary to perform high-quality thermal insulation.
Taking into account these simple rules, parts for the chimney can be purchased back to back, without overpayments. Pay special attention to fire-hazardous roofs; do not skimp on sealing and thermal insulation.
What are sandwich pipes?
What is a sandwich pipe? Sandwich chimney pipes are essentially a conventional design, when one steel pipe is inserted into another. And the formed gap is “filled” with a special heat-protective material. The thermal protection layer carries the entire load during boiler operation, so the outside temperature does not allow condensation to form. And regarding fire safety, this is very good. There is no direct contact with ceilings and walls, which makes it preferable to install such pipes in wooden houses. Otherwise, the stainless steel sandwich is completely identical, with a classic single-layer channel.
Sandwich pipe assembly
- Smoke installation.
- Installation "by condensate".
The first option is not entirely correct from the point of view of organizing high-quality smoke removal, since the formed condensate will fall into the cracks and gaps of the middle layer. This happens due to a loose fit. It is very difficult to notice this, especially during installation, but over time the problem will manifest itself. And when frost sets in, water that gets into the heat insulator will simply “break” the chimney.
Two installation principles: “smoke” and “condensate”
The second type of assembly is more preferable and correct. With this solution, all moisture flows freely through the sealed joint and enters the condensate receiver. Things will be the same externally; drops will flow down the seams without getting into the heat insulator.
Do-it-yourself sandwich chimney installation
The installation of a stainless steel sandwich chimney itself will not cause any difficulties. When installing a chimney with your own hands, remember an important rule: this should only be done from the bottom up. That is, we first work with the boiler, gradually moving towards the roof, so we, as it were, put the upper pipe on the lower one. When installing a chimney or sandwich panels with your own hands, remember that one of the edges will be narrowed. It is this edge that needs to be inserted into the upper pipe so that the seam is made from top to bottom, but not vice versa. By the way, you can also use a tee during installation; it will get rid of accumulating soot and allow condensate to drain into a special receiver.
In places where there is a passage through walls and ceilings, places for brackets for a chimney made of sandwich pipes must be reinforced. To ensure that the transition area is held securely and is not permeable, you can cut a larger hole, cover it with a slab of plywood, screw an asbestos sheet on top, and “galvanize” on top of it. After this, we cut a hole of the required diameter and carry out installation.
The most critical moment in installing a chimney is the passage through the roof. To do this, you will need to attach a galvanized sheet from the inside through which to pass the pipe. When it is completely removed, screw on the “galvanization”. You can bring the edges under the roof, further finishing it.
Don’t forget, if the roof is flammable, you need to install an additional deflector to prevent sparks from hitting the roof.
When the pipe has been completely removed, work can be done to strengthen the joints. This can be done using ordinary clamps. An example of fastening joints: we make connections between each other with a crimp clamp on one side, and joints with other elements, such as tees or adapters, on both sides with the same clamps.
The final stage, after the entire installation is completed, it is necessary to remove the protective film (in places where it passes through the ceilings in advance). Afterwards, it is recommended to seal the seams with a sealant; take into account the heat resistance (at least 1000) when purchasing.
There are also special rules for applying sealant:
- For internal channels - on the outside of the upper internal part.
- For external channels - by appearance.
- In transitions - by appearance.
The main advantages of sandwich panel chimneys
Stainless steel chimneys have the following qualities:
- Easy to install.
- Compact.
- Universal. There are exits both upstairs and through the wall.
- Multi-layered. Best protection against condensation.
- Wear-resistant and not susceptible to aggressive influences. Resistant to even the most aggressive chemicals.
- The most fireproof of all those currently on the market.