IN last years More and more chimneys are being made from sandwich pipes. The point is a relatively low price, long service life, and quite attractive appearance. It is also important that it is possible self-installation sandwich chimney. 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 than one is created indoors comfortable conditions. 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 | 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 | More cheap option AISI 316 with less 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 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 Sandwich pipes are well suited for gas boilers where it is important to prevent leaks. 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 along external wall raise 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 flash master or an apron for round pipe made of galvanized steel.
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 are necessarily 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 assembly is used if the pipe goes indoors (out through the roof). Condensate flowing through the pipe, of course, spoils 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;
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 higher than 5 m, then the pipe should rise above 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 elbow, which means that when equal conditions, 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 attach 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 it is maintained fire safety standards. 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 profile pipe small 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 rafter legs 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 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 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.
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 big choice materials for the installation of smoke removal 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 for filling 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. What if wooden surface is subjected to constant heating for more than 24 hours in a row, it can spontaneously ignite even at a temperature of 170 ° C. Therefore, when installing a sandwich chimney, it is important to observe all safety measures fire safety. 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 wooden structures- joists, ends of rafters, sheathing - is provided 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 case of penetration interfloor ceilings 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 site 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 of floors at the passage point metal pipes from the stove with basalt fiber cardboard
Installation of polyurethane foam chimney
The process of installing cutting in wooden floor can be broken down into a number of sequential 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, outer pipe sandwich: the bottom is inserted into the top. 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.
Smoke is a constant companion of the combustion process and can pose a threat to humans. Therefore, a specific system must be installed that allows it to be removed. This is a well-known chimney. And the efficiency of removing combustion products depends on how correctly it was chosen and installed. Failure to do so may result in a fire or carbon monoxide poisoning.
Before you begin installation work, you need to carefully study all the recommendations of professionals, since you can install a chimney correctly by thoroughly and thoroughly studying the installation process.
What should a proper chimney look like?
The installation of a smoke exhaust system is usually carried out during the construction of a house parallel to the device heating equipment. And if earlier brick was used for this, a fairly durable material that retains heat well, today the sympathies of developers have leaned in favor of ceramics. There are a number of reasons for this, but the most important, perhaps, is the incompatibility of modern heating devices and brick chimneys. In addition, there is no longer a need for the rather expensive services of professional stove makers, since modular systems You can assemble it yourself and much faster.
Whatever design the chimney has, it must satisfy the basic requirements for it.
- Normal draft in the system. If the device is leaky or faulty, then backdraft is created - a process when, instead of removing smoke from the body generator, it, on the contrary, is thrown into the room in which it is installed.
- Safety. The safety of the chimney must be ensured both for those living in the house and for the building itself, that is, it must be taken into account how to install the chimney correctly.
- Aesthetics. This may not be a matter of primary importance, but it is still important. The external chimney should not spoil the appearance of the house from the outside, and the internal chimney should not disrupt the harmony of the internal space.
- Durability. This is another important requirement regarding chimneys.
Here you can also add condensation in the chimney and soot on its inner walls, which should form in minimal quantities, and low thermal conductivity.
There are certain recommendations that also apply to the cross-section of chimneys. It cannot be smaller than the cross-section of the furnace or boiler to which it is connected. The most effective is the round channel. It does not form “dead zones”, it is ensured free movement air, and the soot that forms on the walls can be easily removed.
Options for correct design of chimneys
When starting to install a chimney, many factors are taken into account. The height, diameter and thrust force are selected based on the principle of proportionality between the increase in thrust and the increase in height. The optimality of the design primarily determines its efficiency and safety, and then its appearance and combination with other exterior elements.
When choosing a system design, the characteristics of the room and the installation location of the body generator are important. There are external and internal chimney installations.
External chimney design
The external design of the smoke exhaust system consists of
- a flue that connects the exhaust pipe of the heat generator and a pipe located outside,
- pipe sections,
- revisions.
This chimney is quite safe and easy to install. Its advantages also include complete independence from the nature of the interior of the premises. In this case, the outside must be provided chimney insulation. The optimal shape for it is considered to be a cylinder. The configuration is chosen to be as simple as possible, so that less soot is deposited. If it is impossible to do without horizontal sections, for the normal functioning of the system, their length should not exceed one meter.
Internal chimney design
In this design, the pipes are placed directly in the room that is to be heated. In this case, grooves, a protective casing for the chimney and supports must be installed. Such a chimney does not need insulation: in the absence of thermal insulation, heat will be released into the living space. The exception is unheated attics.
Such designs carry certain risks:
- the likelihood of a fire if the fire protection of chimneys is performed poorly;
- danger of gas poisoning if the system is depressurized.
Combustible materials, walls, partitions that are located close to the pipe are necessary: the same applies to the places where it exits outside.
In addition, the design of such a chimney is somewhat more difficult to install and maintain than an external one. The chimney is brought to the roof using passage pipes and a roof outlet. The roof sealing is ensured by the roof groove for the chimney. Let's look at the main points of installation in more detail.
Installing an internal chimney: what to pay attention to
The chimney is connected to the heating apparatus using a tee, pipe and system elbow. The lower parts of the pipes are connected in series to the upper, with the upper part partially entering the lower. Thereby,
- rising smoke in chimney will not encounter obstacles on its way,
- condensation will not flow out,
- moisture from the outside will not get on the insulation, and it will remain dry.
The housings of the elements are connected using rivets or self-tapping screws.
The joints of the internal pipe elements are sealed using high-temperature silicone sealant.
Brackets are screwed to the wall every 1.5 m, which are used to secure the pipe.
When installing a chimney in areas interfloor ceilings the most important thing is to ensure its fireproof passage, since floor materials usually ignite easily. For this purpose, special insulating feedthroughs are used. In addition, an air gap is left between the ceiling and the smoke duct and non-combustible mineral insulation is installed around the hole.
One of the important points that can cause difficulties during the interfloor installation of a chimney duct is the correct calculation of the parameters of its design - it must pass through the openings of the floors without joining the links - entirely.
Another difficult, but very important point is the output of the chimney structure to the roof. The safety measures taken here are similar to those used during interfloor installation. The exit is sealed with roof grooves, they are selected to the required angle of inclination of the roof of the building. Its conical part regulates the slope, and the edges of the sheet are secured under the roof ridge. At the junction of the chimney pipe and the cutting, the tightness is ensured by an adjustable special apron.
Today, installing a stainless steel chimney is becoming more commonplace than brickwork for removing combustion products from a residential building. Popularity of prefabricated structures modular type made of stainless steel, including chimneys, due to ease of assembly, reliability and long service life. For their production, only high-quality chrome-plated material, steel sheets and galvanization, as well as alloys with various percentage metals known for increased resistance to external environmental influences.
Main parameters of stainless chimneys
In the modern construction market, chimneys made of stainless steel and various other alloys are presented in a large assortment, and they all meet basic operational requirements. There are chimneys for various types boilers:
- diesel;
- gas;
- solid fuel;
- combined type;
- universal.
Metal chimneys vary in shape:
- straight;
- telescopic;
- stainless steel sandwich chimneys;
- corrugated flexible stainless steel chimneys.
The quality of installation not only affects the rapid formation of stable draft, but also the efficiency of the boiler and the safety of the residents of the house. Do not forget that during the combustion process, depending on the type of fuel, not only heat is released, but also:
- soot;
- volatile acid compounds;
- gaseous combustion products;
- carbon monoxide;
- volatile resins;
- ammonia and other compounds.
To protect yourself and your loved ones from any troubles, it is important to ensure that all these harmful volatile compounds are removed through the chimney, especially carbon monoxide or CO. During installation stainless chimneys It is equally important to comply with all safety measures and legislative norms. They are set out in specialized literature and legislative acts.
The essence of these standards is that it is important that the cross-section of the chimney corresponds to the power of the boiler, the height of the chimney is more than 5 m, and it is installed above the roof level in order to avoid turbulence and backdraft. And the chimney duct must have a minimum of turns and broken sections. The dimensions of stainless steel chimneys are initially taken into account by manufacturers, so industrial production takes into account these standards.
Basic requirements for the chimney:
- smooth surface and rounded shape promote stable traction;
- condensation formation is minimal;
- high levels of heat resistance and tightness;
- ease of installation and maintenance;
- fire resistance and safety.
However, all these advantages can be guaranteed only if you follow all the recommendations for assembling the structure, which are shared by experts - stainless steel chimney installation: video.
Attention: When purchasing modular-type stainless steel chimneys, be sure to thoroughly study the section in the instructions that deals with its compliance with the power for which the boiler or stove is designed!
In addition to proper installation, accessibility to the chimney is no less important - for its cleaning and maintenance, as well as condensate drainage, which requires a separate pipe.
Flexible stainless steel chimneys greatly facilitate the installation of autonomous heating system, especially if it is impossible to maintain a straight path for the smoke exhaust system. The corrugation is also effective at high temperatures, up to 900°C, when working on fuel oil, and is also not afraid of temperature changes and quickly warms up, providing stable draft when starting the boiler. The main parts of the prefabricated structure are similar, but the chimney pipe itself is different.
IN brickwork Sometimes fairly wide channels of an ellipsoidal cross-section are used, that is, with an oval cross-section. Their shape also does not contribute to the accumulation of soot and smoke from reverse draft.
Also produced:
- single-circuit or single-wall chimneys, the so-called mono-systems (a variant of a chimney without insulation), which can withstand temperatures within 450°C, applicable inside a building, including corrugation;
- double-circuit thermal systems (with a double or triple layer of chimney) on basalt wool insulation between metal.
There is also the possibility of additional insulation of a stainless chimney, which will be discussed in the last section of the article. But it will only be needed for external structures.
The quality of operation of the smoke exhaust system is also affected by:
1. Wall thickness, which is calculated and specified in the standards:
- for gas boilers, the thickness of the chimney duct ranges from 0.5 mm,
- on diesel fuel - from 0.8 mm;
- for solid fuel boilers - from 1 mm.
2. Configuration. The ideal chimney is straight, and the fewer bends, turns and protrusions, the more efficient the draft and the less accumulation of soot. A smooth cylindrical chimney pipe of sufficient cross-section contributes to efficient operation.
3. The proportions of the diameter (section), length of the pipe or height of the chimney provide sufficient draft force. Stainless steel chimneys with a diameter smaller than necessary for normal operation reduce the efficiency of the boiler, fireplace or stove. Experts also say that it should rise above the top point of the roof by at least 20 cm, and the chimney itself should be no shorter than 5 m.
Special parts solve problems with its maintenance:
- inspection with soot removal;
- condensate drainage;
- air intake for the combustion process;
- chimney for protection from precipitation.
What metal is used for chimneys
“Stainless steel” is a group of steel-based alloys with a small chromium content or galvanized sheet iron- “galvanization” is more correct. Such products are distinguished by excellent anti-corrosion characteristics when interacting with oxygen, water and the aggressive environment of acidic compounds released during combustion. This provides a few microns of chromium oxide deposits, which is why the process is called "chrome plating".
Various grades of steel are used for chimneys:
- 430 - casings and other parts for low-aggression environments;
- 409 - contains titanium, used for pipes of fireplaces, solid fuel boilers and stoves;
- 316 - with the addition of nickel and molybdenum for heat resistance and resistance to acid compounds in diesel furnaces;
- 304 - with the same additives, but in smaller quantities for less aggressive environments;
- 321 - universal grade for chimney pipes with increased heat resistance, up to 850°C;
- 310 - the most heat-resistant, durable and durable chimneys for the most powerful heating equipment.
Attention: For multilayer sandwich pipes, steel of different grades is used. On the internal table it is more resistant and heat-resistant, on the external table it is cheaper and simpler, so it does not look as impressive in appearance as a single-layer chimney.
Main elements and their characteristics
The chimney consists of several elements that have different purposes and assembly order:
- tee;
- pipe elbows;
- audit;
- condensate collector.
1. The main element is a long straight chimney pipe of different lengths, and its fragments are connected like a socket without special fastening.
2. An inclined elbow (at an angle of 45°) connects 2 pipes, changing the slope of the chimney, and it is used at the junction of horizontal and vertical fragments.
3. The universal elbow (at an angle of 90°) is also used as a rotary element to change the configuration of the chimney. Several of these elements are used throughout the chimney - from the top to the junction of the boiler pipe.
4. Tees lead flue gases into the chimney and cut off condensate. They are also joined using a socket method or one-on-one.
5. The condensate drain is placed under the tee to drain excess liquid.
6. Revision - open element, which is designed to remove soot from the chimney. Mounted under a tee at the base of a vertical trunk - picture:
Installation of a stainless steel chimney
Modular chimneys received today greatest distribution, thanks to the ease of assembly. This principle makes it possible not to waste time on labor-intensive fastening and sealing of the chimney. Given how extensive the selection of parts for assembling stainless chimneys is, it is possible to vary its configuration as much as possible without compromising the draft and operation of the boilers. Sometimes you can’t do without a corrugation or several bends in order to competently build a chimney with minimal reconstruction of the walls.
1. Preparation for installation involves calculations on the expected configuration of the chimney, a preliminary sketch and marking of the walls along which its fastening is planned. This will allow you to most accurately calculate the total length of the structure and select the necessary rotating parts for the pipe joint.
Attention: Do not forget to add an outer section, which should be at least 25-50 cm above the level of the roof ridge - to ensure traction in any weather.
2. Before assembling the chimney inside the pipe, the seams are supposed to be treated with a special sealant, which guarantees maximum efficiency of the joints. The outer and outer walls do not require this.
3. Proper installation of the chimney is done from the boiler or stove, that is, from the bottom up, sequentially connecting all the bends and pipe links. Docking according to the socket type - when the upper pipe is inserted into the lower pipe using a special latch. If it is not there, but the shrinkage depth is almost half of the outer diameter.
4. The links at the junction must be securely fixed with clamps, which are included in the kit. The finished pipe must be attached to the wall or load-bearing structures at intervals of one and a half to two meters, and separate brackets are used for mounting bends and tees.
Attention: Make sure that horizontal sections and elbows do not rest on communications. The fragments must not come into contact with gas pipes and electrical wiring!
As you can see, it’s quite easy to make stainless steel chimneys with your own hands. To do this you will need 2 pairs of working hands and 1-2 for time. If you still have questions, watch the video on chimney installation:
Tip: Make sure that condensation does not flow past the pipes, falling onto the insulation and insulation. Also carefully treat the joints with sealant. It is important to properly route the chimney through the roof, which is described in more detail in the previous article.
Chimney insulation
This is one of the important stages in completing the construction of a chimney. Without insulation, which is provided only for stainless steel sandwich chimneys, the installation will have disadvantages. With a poorly insulated chimney, ensuring stable draft when starting a boiler or igniting a fireplace is problematic. And its rapid cooling reduces general indicator Efficiency of the entire autonomous heating system. In addition, condensation that forms on the metal walls when the outside and inside temperatures differ, gradually destroys the internal walls of the chimney and reduces its efficiency.
A sandwich-like design is very popular today when installing and insulating chimneys for modern boilers:
- universal;
- solid fuel;
- gas;
- combined.
They operate in interval mode, that is, “stop-start”. Solid fuel boilers They require additional fuel loading and cleaning of the ash pan, so they do not turn off for some time. And constantly operating boilers, when the required temperature is reached when the sensor or relay is triggered, turn off on their own to avoid overheating. When temperature regime the room drops to a predetermined level, automatic heating also works automatically.
During the “sleep mode”, the temperature in the chimney also drops, a difference forms outside and inside the chimney, and condensation occurs. When the boiler warms up for a long time, it slows down the operation of the heating system, which leads to excessive fuel consumption.
A mineral filler is used as insulation - basalt wool, which is known for its excellent fire-resistant parameters. The pipe is wrapped with it in layers and such a “blanket” is secured with wire and/or clamps. These materials are not afraid of high temperatures, so the chimney can operate on any type of fuel, heating up to 1000°C. However, basalt wool needs to be insulated from excess moisture, since dampness reduces the effectiveness of insulation.
For waterproofing, galvanized or stainless steel is used, which is attached with self-tapping screws on top of the finished “blanket”. To cope with such work, you will need metal scissors and work skills. But it is easier to order such caps of the required diameter in a specialized workshop ready-made. And at home there will be no problems in completing the final stage of insulation.
Attention: At the end of the installation, be sure to secure the top of the pipe so that it does not blow away during a strong gust of wind or tornado. A chimney must be installed at the top to protect the entire system from the penetration of precipitation.
1 General rules for the design and assembly of chimneys
The design and installation of chimneys must be carried out in accordance with current regulations:
SNiP 41-01-2003; VDPO (RULES FOR WORK, REPAIR OF OVEN AND SMOKE CHANNELS); SP 7.13130.2009.
The purpose of the chimney is to remove combustion products and provide normal draft to maintain combustion. The draft level depends on the height of the smoke channel and the diameter of the chimney.
When installing a chimney, the following rules must be observed:
- The height of the chimney from the heating device to the head must be at least 5 m.
- The elevation of the chimney above the ridge/parapet is determined according to the diagram (Fig. 1).
- The elevation of the chimney above closely spaced roofs of neighboring buildings must be at least 1.5 meters.
- If the chimney rises 1.5 meters or more above the roof, it must be additionally secured with braces (Fig. 2).
- In the chimney design, it is recommended to provide plugs with a condensate drain to remove condensate and/or inspection to allow cleaning and maintenance of the smoke channel
- If the roof is made of flammable materials, a spark arrester made of mesh with a cell no larger than 5 x 5 mm should be installed in the chimney.
- When designing and assembling a chimney, it is not allowed to narrow the diameter of the chimney, but it is allowed to widen it. (For example, to assemble a chimney heating stove with a chimney outlet diameter of 115 mm, you cannot use a chimney with a cross section of 110 mm, but you can use a 120 mm chimney using an adapter from 115 mm to 120 mm).
- The length of the horizontal section of the chimney should not be more than 1 meter.
- The joints of the chimney elements should not coincide with the places of ceiling and roof passages, passages in the wall.
- Bends and tees must be installed so that they do not bear the load from the weight of the chimney elements installed above them.
2 Chimney design and calculation of mounting elements
CHIMNEY DIAMETER. The diameter of the chimney must be equal to or greater than the diameter of the outlet of the heating device. To transition from one diameter to another, use the “Adapter” element of the corresponding diameter.
SELECTION OF PIPES TYPE. The use of a regular pipe or an insulated pipe depends on the location of the chimney. Conventional pipes are used only in heated rooms. Insulated pipes can be used in heated and unheated rooms, and outside. The choice between a regular and insulated pipe in heated rooms is made by the consumer, comparing cost, fire safety and comfort during operation. To switch from a regular chimney pipe to an insulated pipe, use the “Transition from non-insulated to insulated” pipe.
SUPPORTING PLATFORM. The choice of chimney design with or without the use of a “Cantilever Bracket” support platform is determined by the design of the heating device and the location of the chimney.
Without a support platform, it is only possible to use a flat vertical chimney resting directly on the heating device. Figure No. 3.
In all other cases, it is necessary to use the “Cantilever Bracket” support platform. Figures 4, 5, 6. The location of the supporting element “Cantilever bracket” should be at least 5 meters along the height of the chimney.
TURNING THE CHIMNEY. To change the direction of the chimney, use a “bend or outlet insulated at 45 or 90 degrees”
CONDENSATE COLLECTION AND CHIMNEY CLEANING. To collect condensate from the chimney and clean the chimney, use a “Tee or tee insulated at 45 or 90 degrees” together with the element “Plug with condensate drain” or “Blind plug”.
PASSAGE THROUGH THE CEILING. If the chimney passes through the ceiling, it is necessary to use the “Insulated passage through the ceiling” element. Which should be 70 mm greater than the thickness of the ceiling.
IMPORTANT
- Some heat-generating devices (furnaces, boilers) may have an increased temperature of the exhaust gases. This will require additional insulation building structures and individual design of the ceiling passage assembly to ensure fire safety. During the operation of the chimney, it is necessary to control the temperature on the outer surface of the “Insulated passage through the ceiling” element and, if necessary, replenish the insulation layer as it shrinks.
- The surface of the chimney heats up during operation. If the chimney passes near building structures made of flammable materials, it should not heat them above 50°C (clause 4.39.8 of GOST R 53321-2009).
PASSAGE THROUGH THE ROOF. If the chimney passes through the roof, then it is necessary to use the element “Passage through the roof” or the element “Rubber seal for the roof”, straight or angular. When installing a chimney through the roof, it is necessary to comply with current building codes and fire safety regulations.
COMPLETION OF THE CHIMNEY.
To complete the chimney, standard elements “Umbrella” or “Insulated Umbrella” are used.
IMPORTANT
- For heating installations When operating on gas, the chimney must remain open!
FIXING THE CHIMNEY. The fastening must exclude the possibility of deflection and any displacement of the chimney from the wind or its own weight. To do this, use the “Wall Fastening” element, which is installed at the rate of: 1 fastening for every 2 meters of the chimney.
To calculate the required number of elements, draw a chimney diagram taking into account all the above rules and recommendations. The number of straight sections of bends and tees is determined by the layout of the chimney and its design. Typical chimney assembly diagrams are shown in Figures 3 to 6.
3 Chimney assembly
- Installation of the chimney starts from the bottom, from the heating or heating device upwards. To be able to regulate the draft, install a damper element in the chimney.
- It is recommended to assemble the chimney elements “by condensate” so that condensate and tar deposits do not escape outside.
- All joints of pipes and other elements (bends, tees, etc.) must be sealed with heat-resistant mastic-sealant, carefully connected to each other to the full depth of the landing socket and fastened with a “Clamp” element in EACH connection.
- After installation, a test fire should be carried out, during which it is necessary to check the tightness of the joints and make sure that adjacent structures made of combustible materials are not exposed to high temperatures and do not heat up.
When using the chimney for the first time, an odor and light smoke may appear as a result of the evaporation of oil residues from the metal surface and the crystallization of sealing materials.
When a stainless steel chimney, including a double-walled one, is heated, tarnished colors may appear on its surface, which is not a defect. The chimney needs maintenance. The chimney should be cleaned regularly, at least 2 times per heating season.