Chimney for solid fuel boiler with own hands

The chimney is an important part of the boiler equipment, which ensures the safe removal of combustion products. He is responsible not only for the removal of waste gases, but also for the supply of oxygen, without which burning is simply impossible. The market offers a large selection of chimneys for solid fuel boilers from various materials. In this article we will consider which of them are most effective, and also tell you how to make a chimney for a solid fuel boiler yourself.

Features of choice

Chimney is an integral part of the heating system. Without it, no boiler will work, no matter what fuel it operates. The main task of the chimney is to remove flue gases and products of fuel combustion from the house to the outside. Without it, all the smoke will go into the room, creating a life-threatening situation. Choice and installation of a chimney on a solid fuel boiler is a responsible task, in which it is necessary to pay attention to the smallest nuances and possess certain knowledge and skills.

Thrust force

One of the main criteria for choosing a chimney is the thrust force that it can provide. It depends on it how efficient and quickly the exhaust gases will leave the room, as well as the overall performance of the heating equipment. Thrust in the chimney is determined by the speed of movement of gases, which are formed as a result of the collision of air currents with different temperatures and differences in atmospheric pressure.

The amount of traction depends on many factors, but the main ones are the shape of the chimney( the presence of bends and the length) and the cross-section of its pipes. To get the best possible traction, the chimney must be straight and taper to the top. The more the pipe bends, the weaker the pull, since air requires more effort and time to pass from the boiler to the exit. For this reason, when installing a chimney for a solid fuel boiler, you should try to make as few turns, bends and slopes as possible. For this, it is better to place the heating equipment in a room from which it is possible to immediately pull the pipe out. Depending on the characteristics of the boiler it can be a kitchen, a vestibule or a separate utility room - a boiler room.

Parameters that determine the efficiency of the traction:

1. If the chimney constantly buzzes or periodically starts to make noise, it is recommended to install a special damper( gate) in it. It will help to regulate the traction force and will achieve the highest possible performance.
2. If you notice that the flue gases and smoke are gradually penetrating into the room, then the chimney has a low draft. Typically, such signs appear during the first test. In this case, it is necessary to revise the structure of the structure, make it more direct and eliminate possible malfunctions.
3. To obtain a stable good traction, the height of the chimney for a solid fuel boiler should be at least 5 m. At the same time, the pipe leaving the roof outside should rise at least 1 m above the ridge beam.

Features of

structures If you are familiar with the basics of physics, you should know that the smoke exits the furnace compartment of the boiler spirally, and its speed gradually increases. Such a phenomenon causes the need to equip the maximum direct and vertical chimney. If this is not done, the smoke trajectory will be broken and the traction will be weakened.

Also take into account the shape of the pipe section for the flue duct of a solid fuel boiler. The optimal shape is a circle or an oval. Square and rectangular pipes can not provide the most efficient removal of flue gases. In this case, turbulence will form, quickly there will be a deposit, soot, the pipe will become clogged, the thrust will be insufficient. The choice of the shape of the section and the length of the chimney is determined by the heating system used, the type of boiler and the features of the building.

Types of chimneys

In any solid fuel boiler, the temperature of the flue gases can vary from 180C to 500C.Naturally, not every material is capable of withstanding such extreme conditions, therefore, special high-strength and temperature-resistant raw materials are used for making chimneys.

Types of chimneys depending on the material:

• asbestos-cement;
• brick;
• ceramic;
• metal;
• glass.

Each of the types differs in performance, cost and installation method.

Asbestos-cement chimneys

Asbestos-cement pipes were widely used for the construction of chimneys just some 20 years ago, but they were quickly replaced by more advanced materials. Despite the low cost, such chimneys often did not withstand the high temperature of the combustion products and burst.

In addition, asbestos-cement pipes can be installed only on vertical sections, since they can not be bent. They weigh a lot, and it's quite difficult to master the installation yourself without using large lifting equipment. Another serious drawback is the inability to make absolutely sealed joints between the elements. This is considered a gross violation of the rules for the operation of chimneys in private houses.

Due to the specific composition of the pipe, a condensate is absorbed into its walls, which very quickly destroys it. In other words, although pipes made of asbestos-cement are cheap, they are very unreliable and they are not recommended for chimneys.

Brick chimneys

If you still want to save as much as possible, but do not sacrifice quality, you can build a brick chimney. It will be cheaper than the analogues listed below. It is worth noting that for the installation of this chimney, you can only use burnt fireproof brick( red or chamotte).Such a pipe will withstand any high temperatures and even ignition of soot inside.

But if you remember, we said that a good chimney with a stably strong thrust can only have a round or oval cross section. It is impossible to build such a pipe from bricks - it will be either square or rectangular, which means that accumulations of soot and vortices can not be avoided. In addition, the brick itself is very heavy, and when you consider that the length of the chimney should be about 5 m, the load on the foundation will be quite serious. Before you decide on this option, make sure that the foundation of the house will withstand an additional weight of several centners. For heavy brick chimney it is necessary to build an additional strong reinforced concrete floor. In general, such work requires professional skills, so it is often trusted by bricklayers.

Rough surface of bricks will inevitably accumulate soot, so the chimney will need to be cleaned periodically. In the past, there was even a special profession of chimney sweepers in European countries, as in all houses there were brick or stone chimneys. This profession is still alive today, but chimney sweeps are used only in cases of severe blockages.

Masonry features:

1. The chimney masonry should only be made of solid bricks.
2. For fixation use a conventional cement-sand mortar.
3. The walls of the chimney are laid out in half a brick to a thickness of 12 cm.
4. The dimensions of the chimney and ventilation duct must be a multiple of the dimensions of the brick plus the width of the vertical joints( section 140x140 mm, 140x200 mm, 140x240 mm, etc.).
5. The exhaust gases must not be cooled too much in the chimney, so it is better to place it in the masonry of the inner bearing wall of the building or to attach it to the wall. Those parts of the canal that will pass through unheated rooms, for example, an attic or a storage room, must be wrapped outside with non-combustible thermal insulation material( usually it is made with mineral wool).

Brick chimneys are perfect for solid fuel boilers, because they supply waste gases of high temperature, which does not allow the formation of condensate. On the contrary, if you build such a chimney for a liquid fuel, pellet or other boiler that is constantly operating in the slow burning mode, then the condensate will quickly destroy the brickwork.

Modern designs of boilers are distinguished by a rather low temperature of exhaust gases, so a brick chimney is more suitable for old models or conventional wood-burning stoves. The exhaust gases are saturated with sulfur, which, when mixed with the condensate, forms a destructive sulfuric acid. If you notice dark wet spots on the walls of the chimney, then sulfuric acid has already begun to corrode them.

Helpful Hint: To connect a brick chimney to a boiler with a low exhaust gas temperature, a special insert must be inserted into the duct in the form of a metal or ceramic pipe.

Ceramic chimneys

These chimneys can be used for any boilers, including solid fuel, because the pipe material is immune to extremely high temperatures and aggressive chemical environments. This type of products is considered the most durable and quality, as evidenced by its high cost.

Depending on the permissible temperature of the exhaust gases, ceramic chimneys are classified as follows:

1. For solid fuel boilers, pipes capable of withstanding a maximum of 600-650 ° C are suitable. They are resistant to ignition of soot deposits and can be used in a dry state.
2. For oil and gas boilers it is necessary to use pipes that can withstand a maximum of 400-450 ° C, which can function in a wet state. They have special bends for condensate.

Important: The peculiarity of the ceramic pipe is that it absorbs condensate, and therefore during installation, it is necessary to ensure good ventilation of the external walls.

Since the walls of the ceramic chimney are completely smooth and smooth, they do not practically accumulate soot. Cleaning them is very convenient, and it will have to be done quite rarely. For the assembly use a variety of elements: pipes from 60 cm to 1 m in length. They are connected by means of fittings and special adhesive heat-resistant mastic.

The image below shows the flue device for a solid fuel boiler. It is rather difficult to create such a system with your own hands, so it's better to instruct a specialist. In addition to the ceramic pipe itself, it is necessary to lay a heat-insulating material so that the gases do not cool down too quickly and do not provoke condensation. It is also necessary to build a shell of concrete modular blocks with ventilation ducts and openings for vertical reinforcement. Ceramic pipes should be placed in special vertical channels, for the construction of which they take hollow bricks or concrete blocks. The channel itself can be located in the building's ventilation block. In concrete blocks, in addition to the ventilation ducts, there must be holes for mounting the reinforcement. The part of the pipe protruding above the roof must be reinforced without fail.

Insulation around the pipe is needed not only to prevent too rapid cooling of exhaust gases, but also to protect surrounding structures from fire. As a heat-insulating material, mineral wool is best suited. It is inexpensive and has a proper temperature resistance.

Metal chimneys

Metal chimneys today are, perhaps, the most popular mainly due to the ease of installation. However, their service life is much lower than that of ceramic products, and the cost sometimes exceeds the price of a good brick or ceramic chimney. For the manufacture of pipes use stainless steel thickness of 0.5 mm, capable of withstanding the temperature of gases to 400-450C and the effect of condensate with sulfur.

Important: For solid fuel boilers, pipes made of heat-resistant steel with a thickness of at least 1 mm should be chosen.

Despite the short period of operation, steel chimneys are in demand because they are very easy to install, they do not weigh much and do not require reinforcement of the base for installation or equipment of ventilation ducts. If necessary, they can easily be repaired or replaced one of the sites without disassembling the entire structure.

There are several types of steel chimneys:

1. Single-walled pipes - they can be installed in a special pre-equipped vertical channel. The design features are the same as for a ceramic chimney( insulation, ventilation).A single-walled chimney is suitable for repairing a brick chimney and adapting it to a gas boiler. To do this, the pipe must be simply inserted into the channel. It is possible to make such a chimney with your own hands from sheet steel.
2. Double-walled sandwich-tube - prefabricated construction of finished parts. In fact, one tube is located inside another, which serves as a protective shell. The space between the two pipes is filled with heat-resistant thermal insulation material. For the manufacture of the outer tube using galvanized steel or stainless steel. Such chimneys are very popular, because they can easily be assembled as a designer, and can be installed even in houses where special chimney channels are not provided. Even if you bring them to the roof along the outer wall, it will look neat.
   
3. Coaxial chimney - designed for heating equipment with a closed combustion chamber. The structure is a pipe placed in another pipe. The internal channel drains the exhaust gases, while the outer channel feeds oxygen to the boiler to maintain combustion. Because of this efficiency, the cost of coaxial chimneys is quite high.

Glass chimneys

It's hard to believe, but the chimney can be made even from glass. It is clear that such an exotic product is unlikely to get at home. Nevertheless, factory glass chimneys are the most effective than all the analogues described above. They appeared relatively recently, but immediately demonstrated their exceptional qualities. Since the glass is not corroded at all, condensate is not afraid of it. It is easy to clean, if at all it should be done - a smooth glossy surface almost does not accumulate soot or soot.

The chimney made of glass is the safest and most reliable, but it also has its drawbacks. The main one is a prohibitive cost and a specific installation that requires the presence of a professional. However, compared to the advantages, the amount spent on a glass chimney will pay off in a few years.

Installation rules

From all written above, we can conclude - in order to know how to make a chimney for a solid fuel boiler, you need to know the characteristics of the material in use, have a clear plan of action and a scheme for laying the pipe from the boiler to the roof. Do this work yourself, and even without the proper skills, almost unrealistic. It is much easier and safer to buy a finished product in a store and collect it or invite a specialist.

Here are some recommendations on how to properly make a chimney for a solid fuel boiler:

1. Always mount the elements of the structure, moving from bottom to top.
2. If you use tees, bends or other similar elements, fasten them with metal clips. Make sure that the joints are outside the ceiling.
3. For tees, install brackets for support.
   
4. After every 2 m of the chimney, attach it to the wall, making sure that the pipe does not bend.
5. Do not allow the channel to come in contact with any kind of communication, be it a gas pipe, electrical wiring, etc.
6. When removing the chimney through roofs or floors, keep a distance of 15 cm between the insulated pipe and 30 cm without insulation.
7. If the installation of a chimney is indispensable without creating a horizontal section, make sure that its length does not exceed 1 m.
8. The diameter of the chimney for a solid fuel boiler must be calculated in accordance with the characteristics of the heating equipment( its capacity), the length of the channel and the features of the building.
9. When installing the flue, take into account the fact that the structure can be deformed due to regular temperature loads and swings. That it does not hurt the whole system, install a flexible adapter. If you did not install it for any reason, attach the pipe to the bracket not too tightly - leave a margin of 10-15 mm in case of temperature changes.
10. For roofs made of combustible materials, a spark arrestor must be installed on the chimney. You can buy it or make it yourself from a metal grid with cells no more than 5x5 mm.

To the chimney served you for a long time and did not break, take the rule at least once in six months to look inside the pipe, check its condition and clean it if necessary. Finally, we offer a video about chimneys for solid fuel boilers: