Chimney thermal insulation, its features, advantages and disadvantages, preparatory stage of work, technologies for their implementation. Insulation of the chimney pipe is a primary task to ensure the smooth operation of the heating system at home. About how to properly perform such work, our today's material.
Features of thermal insulation of chimneys
The thermal insulation of the chimney is designed to save it from destruction, for several reasons. The main one is dampness. Despite the fact that the chimney is a warm place, not all moisture is removed into the environment along with the warm air. A certain part of it settles inside the pipe on its walls. In freezing temperatures, condensate freezes, expanding and tearing the brick pipe material. This leads to cracks in the chimney and its further failure. A metal chimney quickly corrodes from dampness.
Another reason is the formation of chemically aggressive substances that inevitably appear during the combustion of a certain type of fuel. The effect of such reagents on the chimney material when mixed with condensate can be compared to the effect of sulfuric acid, which has settled on the walls of a structure and gradually destroys it.
In all these cases, insulation of the chimney pipe can be of great help, which can minimize negative physical and chemical processes in it.
Various materials with low thermal conductivity can be used to insulate the pipe: mineral wool, expanded clay, broken bricks, slag concrete, etc. Their price, in fact, does not matter - the more convenient it is to work, so you can insulate.
The main thing here is not to break the rules below:
- The materials for the insulation of the chimney should not be flammable, since in working order the heating equipment, including the pipe, as well as part of the roof near it, are exposed to high temperatures.
- It is not necessary to create a massive structure from the chimney with thermal insulation in order to avoid that over time it does not push through the roof and does not collapse down with all the heavy ones.
- Before using the selected insulation, you need to carefully read its properties and installation instructions. This information is extremely helpful.
The simplest option for thermal insulation of the chimney and therefore loved by many is insulation using wooden shields. The method consists in covering the chimney with wooden shields. The material for them is wooden blocks 40x40 mm. The size of the cavity between the frame and the chimney should be 10-15 cm wide. It can be filled with sand, glass wool waste, slag, or simply mixed before filling. When insulating the chimney with polystyrene foam or its scraps, the pipe must be brick in order to avoid heating its surface to a temperature that is too high for this material.
The filling of the frame should be carried out in layers, carefully ramming each of them. After completing this procedure, it is recommended to refine the insulated chimney. For this purpose, siding or a profiled colored sheet, which can be attached to the shields with self-tapping screws, are suitable for use. With this method of insulation, the chimney will perfectly keep heat and will relieve the owners of this problem for a long time.
Advantages and disadvantages of chimney insulation
Timely thermal insulation of the chimney can significantly extend its service life. By reducing the temperature difference between the pipe material and the hot air from the furnace or boiler, the amount of condensate formed in the chimney is significantly reduced. At the same time, many aggressive substances are freely removed with smoke, without mixing with condensate and thereby preserving the integrity of the entire structure.
Insulation protects the chimney from the outside from the destructive effects of precipitation, sun and wind, increases its frost resistance. In addition, a decrease in heat losses at home leads to significant savings in fuel for heating it. In the future, there will be additional savings on the current repair of the chimney and roof due to their better preservation.
Finally, a neatly insulated chimney has a more aesthetic appearance due to the use of steel casings and finishing materials in the insulation process.
There are practically no drawbacks to thermal insulation of chimneys, except for the fact that some types of work are difficult for independent execution.
Preparatory work
Before the start of the insulation work, it is necessary to determine their volume: will only the part of the pipe protruding above the roof and passing through the attic be processed or the insulation will touch the chimney along its entire length.
The amount of materials required depends on this. Some of them can be harmful to the respiratory tract, skin and eyes. Therefore, before using them, you should study the instructions of their manufacturer and, if necessary, stock up on protective equipment: gloves, a respirator and special glasses.
It is recommended to clean the chimney before insulating it. This will facilitate the work and give confidence that fungus will not appear inside the structure. This procedure is desirable for all types of pipes, regardless of their material of manufacture.
There are four popular options for insulating chimneys:
- Sheathing of the pipe with mineral wool slabs;
- Making a frame for insulation around the chimney;
- Installation of additional pipes of larger diameter;
- Plastering the surface.
Each of these methods is used depending on the design features of the chimney.
Chimney pipe insulation technology
Due to the variety of types of chimneys, we will consider how to properly insulate asbestos-cement, metal and brick pipes, which are most often used.
Insulation of asbestos-cement pipe
Such thermal insulation is quite capable of performing independently. Its essence lies in wrapping the pipe with mineral wool and fixing the insulation with a metal casing.
First of all, the outer surface of the chimney should be cleaned of dust and other contaminants. Then it is necessary to make several telescopic parts so that the length of each of them is about 150 cm. The parts must be made of galvanized steel in the form of short pipes put on top of each other. The diameters of the casings should be selected so that there is a gap of 60 mm for the insulation between them and the pipe in the assembled state.
The insulation must be laid sequentially, starting with the first casing put on the chimney, and ending with the top of the pipe. During installation, the insulation in the cavity between the pipe and the casing wall must be compacted. In addition to mineral wool, heat-insulating backing can be used. This is technical slag or small brick breakage.
In the upper part of the chimney, it is necessary to create a slight slope, and in the resulting voids between the metal of the casing and the pipe, pour cement mortar. All free space should be filled with it.
Some owners, when insulating a chimney with their own hands, avoid using a galvanized casing. Then it is enough to overlay the pipe with mineral wool in several layers and tighten the entire system with clamps. However, this method has a significant disadvantage: the insulation will absorb atmospheric moisture, gain weight and slide under its weight, which will eventually lead to heat losses and the need to repair the chimney.
Insulation of a steel pipe
Modern steel chimneys are manufactured with ready-made insulation. These are two pipes of different diameters, assembled like a nesting doll. The outer part of such a chimney is made of stainless steel, and the inner part is made of galvanized steel. Thermal insulation material is located between the pipe walls.
The old chimney can be insulated by yourself. To do this, you will need a set of tools, consisting of an electric drill with drills, a screwdriver, an angle machine with a cut-off wheel, a knife, a tape measure and mounting tape.
Before insulating the chimney with mineral wool or a loose insulator, you need to buy a stainless steel pipe with a diameter of 60-80 mm larger. After that, it should be put on the main pipe and carefully secured to the roof. The free cavity between the walls of the two pipes must be filled with the selected insulation, carefully tamping it.
Insulation of a brick pipe
It is more difficult to insulate such a chimney than an asbestos-cement or steel one. There is little material needed for this, so it is recommended to use high quality insulation with low thermal conductivity. Consider the two most common options for thermal insulation of a brick pipe.
The first option is to plaster the surface. It must be said that this type of insulation is ineffective, although it has a right to exist. When using it, you can reduce heat losses, but only by 20-25%. That being said, the effort will be significant.
The method is as follows. A reinforcing mesh must be fixed on the chimney, which must be in close contact with the brickwork. After that, it is necessary to prepare a plaster mortar consisting of sifted slag, slaked lime and Portland cement. The first layer of plaster, 30 mm thick, must be applied to the mesh-reinforced pipe surface. The solution for this should be the thickest.
After the plaster hardens, you need to prepare the solution for the next layer. The process of alternating layers of mortar must be repeated 4-5 times with breaks necessary for the setting of the binder.
The total thickness of all layers applied to the chimney should not exceed 8 cm. After applying the top layer, leveling, trowelling and finishing of the coating must be performed.
The second option for chimney insulation is the use of mineral wool slabs. This method is not easier, but much more effective. It cuts heat loss by 2 times.
Before using it, you should calculate and prepare the required number of insulation boards. If rolled material is used, it should be cut off in such an amount that it is enough for the entire insulated surface of the chimney.
As usual, the pipe will have to be cleaned of dirt, dried and repaired if necessary: to repair cracks, level, etc.
The insulation should be attached to the chimney using umbrella dowels or by stitching it with wire. There should be no gaps at the joints of the slabs or sheets of roll insulation, otherwise the loss of precious heat is inevitable.
After installation, the insulation must be covered with a waterproof mixture to prevent moisture from entering it.
It is recommended to lay a suitable facing material on top of the protective plaster: clay bricks, asbestos-cement sheets or tiles with a thickness of more than 40 mm.
How to insulate a chimney pipe - watch the video:
In conclusion of the topic, it should be noted that it is recommended to carry out thermal insulation of the chimney immediately after the completion of the construction of the house. You can hire a contractor or do it yourself. In any case, chimney insulation will not be too expensive. In addition, the benefits of this event are very large: maintaining the stable operation of the heating system, minimizing the cost of repairing the chimney and preventing its destruction.
