Pipes

Sandwich pipe for the oven: device, principle of operation and installation

May 7, 2020

Today, brick pipes for stoves and fireplaces are installed much less often. This is due to the emergence of more reliable products, which better cope with the removal of combustion products and are easy to install. One such product is a sandwich pipe for a fireplace or stove, which consists of several layers and has high fire safety.

Chimney sandwich for the chimney of the stove or fireplace - the most practical and safe option

Features of sandwich pipes

The chimney is an important part of the heating system, which performs a number of functions. However, the main purpose of this design is to remove combustion products from heating devices. It is also worth noting, that the chimney ensures the safe operation of the entire system.

Sandwich pipes are a very popular solution for chimney installation. Such pipes differ in that, preventing the formation of condensate in winter. The absence of accumulations of moisture reduces the amount of soot deposits on the walls of the products. This allows for preventive cleaning less often and increases the service life of the system as a whole.

The design of the sandwich is quite simple: it consists of two pipes, one of which is located in the other. Inner tube, usually, made of heat-resistant stainless steel, and the external is presented ??galvanized. The distance between the inner and outer pipe is filled with insulating material. Mineral wool can act as insulation, basalt or ceramic wool, as well as vermiculite.

Useful Information! The optimal thickness of the insulating material is selected depending on the purpose and type of recycled fuel.

Sandwich pipe meets all fire safety requirements, therefore such chimneys are irreplaceable for buildings from flammable materials

There is a rule for wooden buildings: the outer pipe must be insulated, to reduce the risk of fire. exept this, it is worth noting, that the products have the best properties, in which the outer and inner tubes are made of stainless steel.

Chimney sandwich is used in various systems, which may have such heating structures:

  • furnaces;
  • fireplaces;
  • gas columns;
  • boilers.

Installation of such pipes requires compliance with building codes and regulations, as well as fire safety requirements. Ignoring the rules can lead to fires and endanger the lives of the occupants of the house, therefore, the constituent issue must be taken seriously.

Requirements, which must correspond to the sandwich pipe for the furnace

Smoke construction, which carries out the removal of combustion products outside the house, must meet certain requirements: have high strength characteristics, long service life, as well as good heat resistance. Among other things, chimney must ensure efficient removal of combustion products from heaters and comply with all modern fire safety regulations.

The sandwich pipe has a round cross section, this provides good aerodynamic performance

Consider the main criteria, which determines the quality of such a pipe:

Aerodynamic indicators. They depend on several important factors. First of all, it is a form of pipe crossing. A product with a round cross section is the best solution and does not interfere with the circulation of air flows, which allows you to maintain good traction in the system. Traction problems are quite common and are often related to this, that design, consisting of sandwich parts incorrectly mounted. For normal traction in the system, the number of horizontal sections should be taken into account, tees, taps, etc.. D. Another important factor, which affects the aerodynamic properties of the system - the smoothness of the inner walls.

Ease of operation and maintenance. In brick structures, the walls of the inner channel, usually, contain depressions and protrusions, which interfere with normal air circulation, and also collect soot and soot deposits. Therefore, such systems require frequent cleaning. Sandwich designs have smooth inner walls and the operation of such systems is much easier, because they do not accumulate layers of soot in short periods of time.

Resistance to corrosion. Chimney corrosion is a common problem, which leads to the destruction of pipes. Exhaust gases contain aggressive chemical compounds, which in combination with condensate destroy the walls of the pipes. The inner channel of the sandwich design consists of stainless steel, which is resistant to corrosion. exept this, as mentioned above, no condensate is formed in such systems. Therefore, if you compare the sandwich design with a brick chimney, then the first, certainly, is more reliable.

Importantly! Experts recommend laying sandwich chimneys in the inner wall of the house. It is desirable to install such a structure with the conclusion through the roof as close as possible to the ridge.

Such a chimney, like a sandwich, it is possible to deduce without a special pipe not only through a roof, but also through the wall

However, in some cases this is not possible, therefore it is possible to spend it a flue through a wall, but you have to remember, that such an installation is associated with some difficulties. Example, pipe, located outside the house, it is necessary to insulate well, protecting it from freezing in winter. Chimney insulation, coming out, will help to avoid condensation. The walls of such a channel must be thicker, than in indoor structures. The same applies to thermal insulation material, located between two sheets.

Advantages and disadvantages of sandwich pipes

Sandwich pipe for the fireplace, stoves and other heating equipment, has advantages and disadvantages.

Consider the main advantages of such products:

  • versatility of installation. The pipe can be removed through the roof of the house, and through the wall;
  • ease of installation. The design of a sandwich product allows to mount it without special difficulties. No special construction equipment is required for installation. All this allows you to speed up the laying of communication from such pipes;
  • no condensate. The chimney sandwich device eliminates the formation of condensation, and also slows down the accumulation of soot. If necessary, you can additionally install a special tee, which prevents condensation;
  • compactness. Large spaces are not required to install a sandwich system, which is very convenient;
  • security. Such pipes differ in that, that they can be installed even in wooden houses and other structures made of this material (example, baths). Sandwich chimney is safe, if all conditions of installation of such system are observed;
  • require minimal care. Preventive inspections and cleaning of such a structure are carried out much less often, than for chimneys, made of other materials;
  • reliability. Stainless Steel, from which internal are executed, and sometimes external, pipes in a sandwich, differs in excellent anticorrosive qualities, as well as resistance to high temperatures;
  • plasticity. Today in the construction market you can find any components for such chimney structures. A large selection of components allows you to lay the chimney, wrapping around the beams, rafters and other obstacles, which may be encountered in the path of the chimney sandwich during installation;
  • saving. Sandwich pipes for stoves and fireplaces can reduce not only temporary, but also financial costs. This design does not require a separate foundation;
  • long service life. Properly covered, it will withstand a great deal of adverse conditions 15-20 years.

Accessories for sandwich systems are available in a very wide range, this allows you to create chimneys of various configurations

However, sandwich chimneys have their drawbacks. Consider them:

  • despite the fact that the service life of such a pipe is higher, than a brick, it is not recommended to use it anymore 10-12 years. After this period, it is desirable to carry out repair work or complete replacement of the structure.
  • if the pipe is operated in conditions of constant temperature jumps, there may be a deterioration in tightness. It is recommended to check the fastening of such structural elements of the chimney at least once a year.
  • the main disadvantage of such sandwiches is their high price, due to ??ease of installation and excellent technical characteristics.

Sizes of stainless steel sandwiches

Buying a sandwich, it is necessary to pay attention to indicators of section of an exit of a branch pipe from a copper. The diameter of the sandwich must be at least this value. It has to do with that, that the pipe is provided at the outlet of the pipe and from this point begins its laying.

Indicators of section of an internal pipe from stainless steel can be from 100 to 300 mm. And it's worth remembering, that such parts are produced in segments 0,5 or 1 m. The wall thickness of such products may vary depending on the purpose of the pipe (0,5 or 1 mm).

Importantly! Components for the sandwich chimney have certain angles, which are worth paying attention to. The corners have an angle 90 °, and tees can be of two types: 90 and 135 °.

The thickness of the insulating layer often does not exceed 6 cm

The thickness of the insulating layer between the inner and outer pipes may differ, however, most common indicators - 4-6 cm. The dependence of the outer diameter of the sandwiches on the inner is presented ??in table № 1.

Table 1

Do inner tube, mm Du outer tube, mm
300 350-400
250 300-350
200 250-300
180 250
150 200-250
140 200
130
120
115
110
100

There are a number of rules to consider when removing the chimney through the roof, related to this event. The correct location of the flue pipe provides a good output of combustion products and normal draft in the system.

Determining the height of the chimney above the roof

When calculating the length of the flue over the roof, the following rules must be observed:

  • the height of the flue must be at least 5 meters. Such indicators are required for normal traction in the system, which ensures the removal of combustion products. If the channel length is less, than 5 meters you need to install a special device, which will increase traction - an electric smoke extractor;
  • over a flat roof it is necessary to mount a sandwich pipe so, to make it rise at least by 0,5 m above the roof material;
  • if the distance from the roof ridge to the sandwich pipe is less than 1,5 m, the pipe should rise above the ridge at least on 0,5 m;
  • if the distance from the ridge to the chimney is from 1,5 to 3 m, then the pipe can be mounted flush with the upper edge of the roof;
  • if the distance from the ridge to the pipe exceeds 3 m - the height of the structure must be below the level of the upper limit of the roof with a slope of not more than 10 °;
  • when installing a stove sandwich pipe in the bath must take into account another important rule: if there are buildings above the bath nearby, then the pipe is mounted above these objects.

The height of the chimney is calculated depending on the shape of the roof of the building, proximity to the grasshopper, as well as the presence of other structures around the house

structural elements

The main details of such a chimney are straight lengths 0,5 and 1 m. However, exept this, there are auxiliary parts, which are worth paying attention to:

  1. Horizontal sections. In the people such sites name "sunbeds". Connection of such details is carried out by means of auditing tees. This is necessary for that, to avoid clogging the structure.
  2. Tee. Construction element, mounted at the beginning of the vertical channel and performs the function of eliminating condensate and unwanted debris in the system. In most cases, tees are installed immediately after the exit of the structure through the wall. One of the outputs of such a product is made as follows, so that you can remove the accumulated moisture in it.
  3. Corner. Such an element is necessary to change the direction of the structure at right angles. Such products are made of the same materials, of which the sandwich pipe is made. Insulated with an additional layer of insulation.
  4. Compensator. Sandwich chimney under the influence of high temperatures, usually, expands in a linear direction. The compensator is needed to balance the movement of the structure. In multi-storey buildings, such devices are usually mounted on each floor.
  5. Checkpoint node. Construction, which is mounted in the ceiling and roof and provides passage of the pipe, through these overlaps. Is a protective box, containing heat-insulating material.
  6. Waterproofing apron. Installed around the perimeter of the flue pipe on the roof to protect the roof openings, through which the sandwich chimney passes.
  7. Clamps. Fasteners, which provide reliable fixing of a design to walls and ceilings.
  8. Protective cap. Element, installed at the end of the flue pipe on the roof. Protects the chimney flue from precipitation, as well as garbage.

All structural elements of the chimney (taps, corners, tees and more) are also equipped with a layer of thermal insulation

Choice tips

Experts recommend being careful when choosing sandwich pipes for the oven and pay attention to the following points:

  • first of all it is necessary to check up quality of material, from which such a product is made. Good material is the key to that, that the structure will not fail during operation;
  • the second important point is the density of the insulating material between the two pipes. It is recommended to buy products with insulation, which is able to withstand at least 700 ° C;
  • do not forget about welds. For stoves and boilers, which generate heat by burning solid fuels, it is recommended to buy a sandwich pipe with seams, performed by laser welding. Ordinary skating seams are also suitable for gas boilers;
  • it is very important to remember, that the inner tube in the sandwich must be made of stainless steel. Galvanizing is only suitable for gas boilers;
  • if the chimney is used for a solid fuel stove is desirable, so that the outer layer was made of stainless steel. However, in this case, galvanized steel is also allowed, but not copper, brass, etc.. D .;
  • stainless steel has its own brand. The brand is determined by the technical characteristics of the metal. The most suitable brands for making inner pipes in a sandwich are 316 You, 321 and 310S. Such brands are able to withstand the temperature 850 ° C, and the latter - more 1000 ° C.

Temperature indicators of combustion products depending on the type of heating equipment and fuel are shown in table №2.

Table 2

heating equipment fuel Smoke temperature, ° C
fireplace Firewood

 350-650
oven
Bath stove Firewood 350-700
boiler

 coal 500-700
gas 120-200
Diesel fuel 160-250
sawdust 220-240

How to make your own hands?

To date, it is easy to buy all the necessary materials for this, to Make a Sandwich Pipe by Yourself |. The work on the installation of the sandwich must be performed in stages.

Insulated pipe can be made yourself, but for this you need to find suitable materials

However, before you start it, you need to buy and prepare all the necessary materials:

  • stainless steel pipe;
  • heat-insulating material;
  • sheet of galvanized iron.

pay attention! You can choose any suitable material as insulation. Basic rule, which should be guided - the purpose of the future design. Based on this, we can determine, what temperature will be in the system and choose the right insulation.

The thickness of the insulating layer, as mentioned above, can be from 4 to 6 cm. exept this, it is worth noting, that expanded clay or polyurethane can be used as insulation.

Once the insulation and other materials are selected, you can proceed directly to the assembly of the structure. First you need to lay the insulation material on the inner stainless steel pipe. Then turn the resulting workpiece into a sheet of galvanized steel. Usually, the outer tube consists of several fragments. It is necessary to pay special attention to fastening of separate fragments of a design. Self-tapping screws are suitable for connecting galvanized iron. The surface of the sheet must be well fixed with them, and also to fasten together separate fragments of galvanization (if any).

Pipe section, adjacent directly to the heater is exposed to high temperatures and can burn out. Therefore, it is recommended to mount this section as follows, that it was possible to make its operative replacement in case of breakage. It is important to remember, that in contrast to the purchased products, such pipes are more difficult to mount. Assemble the chimney as a designer will not work. Based on this, it is recommended to fasten all design at once.

When laying pipes through the ceiling and roof should take care of it, to eliminate the risk of ignition of the floor material. To do this, a special steel box is mounted in the place of overlap, filled with insulating material.

The passage of the pipe through the roof must be performed in accordance with fire safety regulations

Preparation for installation of a chimney from a sandwich of pipes

Preparation includes project planning, as well as the necessary design calculations. The project of future communication is drawn on paper, thereby determining the best way to lay it. If necessary, you can download a ready-made project online. But you need to remember, that each case is unique and experts recommend always to make individual projects.

exept this, it is strictly forbidden to place the sandwich pipe directly above the stove. This requires the installation of a furnace gutter, which will come out of the furnace. Such a gutter must be made of heat-resistant material, to withstand high temperatures. The sandwich part is attached to this gutter with a special adapter.

Once the project is completed, it is necessary to start calculation of materials and details. It all depends on that, which pipes you use - homemade or purchased. The calculation of finished pipes is quite simple, since they are manufactured to certain standards, but in case you decide to collect all the elements of the chimney with your own hands, will have to be patient. The calculation of materials is carried out for each case individually, however, it is recommended to buy them in stock.

Then you should do all the necessary marking. Marking is performed for brackets. It is very convenient, since the brackets are located every meter. Proper markup is an important point, which will maintain the verticality of the system. Then you need to mount the bushings (boxes).

Installation of a pipe is carried out from below upwards, last of all the part is mounted, coming out of the roof

Installation of sandwich pipes

Joining pipes together is quite simple: the inner pipe of the upper part of the chimney joins the lower element of the second pipe. So, a tight and strong connection is obtained.

Importantly! Laying a sandwich chimney is always carried out from bottom to top.

Experts recommend applying a special sealant to the pipe sandwich joints for extra reliability. Such a sealant must be resistant to temperatures not lower 100 ° C. exept this, separate parts of a design are fixed by means of special clamps and arms.

In the vast majority of cases of installation of a chimney from sandwich pipes there is a need to make turn. You can rotate in two ways:

  • return design to 15, 35 or 45 °;
  • on 90 °.

The first option is mainly needed to bypass the obstacle when laying the pipe through the ceiling or roof, and turn at right angles, usually, the chimney sandwich through a wall is necessary at installation.

The passage through the floor should be performed vertically or horizontally (through the wall) position. Any deviations are not allowed. When laying the chimney through the wall, remember, that the length of the horizontal segment should not exceed 1 m. Otherwise, such a system will have problems with traction, easy to clog and will soon fail.

Among other things, must be traced, so that communications inside the house do not come into contact with the sandwich structure. This rule applies to all networks: gas pipes, electrical cables, etc.. D.