The optimal pipe diameter for the chimney of a solid fuel boiler. Refractory brick chimney. Other properties of solid fuel boilers

Due to the constant rise in the cost of traditional energy sources, heating installations that burn wood, coal and other types of fuel are becoming more widespread. The owner of a private house, who has decided to purchase such a product for heating, needs to create conditions for its normal operation. To ensure stable combustion and efficient removal of flue gases, a good chimney for a solid fuel boiler is required. It plays an important role, especially in cases where the unit is not equipped with forced air supply devices and the combustion process depends on the natural draft created by the chimney.

Types and a short description of chimneys

Flue gas discharge devices differ into several types in terms of design and type of execution:

1. Brick vertical ducts built into the inner wall of the house together with ventilation shafts. This also includes new types of built-in ducts - ceramic rectangular gas ducts.
2. Chimneys attached to the outside of the wall of the house. Also made of red ceramic bricks.
3. Vertical metal pipes running inside the building with access to the roof.
4. Steel pipes for the removal of combustion products, located outside the cottage. They can be attached to a wall or to a free-standing lattice mast made of rolled metal.

In houses built of bricks or blocks, ducts for ventilation and removal of combustion products are provided in advance by the project. Most often, a brick chimney for solid fuel boilers is arranged in the inner wall of the building, adjacent to the furnace room. In older houses, you can find gas ducts attached to the outer wall and resting on a separate foundation.

The disadvantages of brick diverters are as follows:

1. The inner surface of the brickwork consists entirely of irregularities and roughness, contributing to the intensive deposition of soot on them from the combustion of solid fuels.
2. The rectangular design of the chimney has inferior aerodynamic characteristics in comparison with the round one and increases the resistance to the flow of gases, the force of natural draft is lower.
3. Brickwork, attached outside the house, due to the temperature difference, begins to separate from the wall and a crack appears between them. If the extension was laid out later than the main construction proceeded, then the crack width may be even greater due to the foundation settlement.
4. Condensation formed on the walls of the masonry penetrates into the pores of the material and, under the influence of low outside temperatures, destroys it. The result is shown in the figure.

A vertical chimney made of ceramic bricks is quite suitable for connecting a solid fuel boiler, since it is durable and in good harmony with the exterior of a brick mansion. To eliminate its inherent disadvantages, it is necessary to modify the design of the gas duct or to execute it correctly even at the construction stage, which will be discussed below.

Construction of two steel pipes with a layer of insulation - this is a modern correct chimney... It is assembled from separate sections with a length of 1-2 m, which are lightweight, so even one person can do the job. The inner part made of stainless steel is smooth, soot does not settle on it, and condensate flows freely into the lower part of the structure, from where it is easily removed through a special pipe.

One of the latest technical solutions for the removal of waste gases is a metal coaxial chimney. The principle of its operation is that combustion products exit through the internal section, and air from the street enters the combustion chamber through the space between the walls. Such air ducts are allowed to be used in conjunction with heating units, in which such a possibility is provided. As a rule, these are installations with forced air injection and a closed firebox. To make sure of this, it is imperative to study the technical data sheet for the product.

It is better to improve the existing brick chimney for a solid fuel boiler by taking a number of measures. One of them - the sleeveing ​​of the mine, is done with the aim of:

• change the rectangular section of the channel to a round one and thereby improve its aerodynamic characteristics;
• make the inner walls of the flue smooth to prevent soot from settling;
• additionally insulate the space between the round sleeve and the square opening and protect the material from the effects of condensation.

The essence of the event lies in the fact that a round metal pipe of the corresponding diameter is inserted into the rectangular channel along its entire height. On the side, 2 holes are cut out in it, one above the other, the first is for connecting the outlet from the boiler, and a hatch is mounted in the second - revision. To avoid the ingress of precipitation, the outlet is closed with a decorative umbrella, a deflector - a spark arrester or a rotating weather vane. Insulation, usually basalt wool, is stuffed into the cavities formed between the round pipe and the rectangular channel.

The destruction of the material of the walls of the mine from the effects of condensate is possible by insulating them from the outside with plates of basalt fiber 80-100 mm thick. If the channel is located in the inner wall of the house, then it is necessary to insulate its upper part, which is located in an unheated attic and above the level of the roof. Attached smoke shafts should be lined with heat-insulating material as a whole, sheathing the insulation from the outside with galvanized metal 0.5 mm thick.

Performing a brick chimney device in order to connect a solid fuel boiler to it, you can use modern ceramic materials. They are rectangular blocks, inside of which a circular channel is made.

The main shaft is assembled from such blocks to remove combustion products, and from the outside it is lined with masonry made of decorative stone such as "bassoon" or another, depending on the exterior of the cottage. In this case, additional insulation is not required.

Since ceramic blocks and their installation are not cheap, a cheaper option can be used during construction - to make the same sleeve metal pipe with insulation.

Calculation of the distance and height of the chimney

During construction, the height of the chimney for a solid fuel boiler must be maintained in accordance with regulatory documents. The stable operation of any heating installation that burns coal or wood depends on this. The required height provides the natural draft force to create a vacuum in the furnace of the unit, and also dissipates the combustion products in the atmosphere. The requirements of regulatory documents apply to all types of pipes, regardless of what material they are made of. There is a chimney scheme for a solid fuel boiler, which must be adhered to during construction:

As an example, it is proposed to consider a design scheme with the following initial data:

• the height of the building in the ridge is 6 m;
• the distance from the smoke exhaust device to the ridge is 6 m.

Of course, open pipes increase the efficiency of heating, but you must remember that in this case, safety - at least 30 cm must share the chimney from any flammable elements of home and construction equipment. They are adapted for outdoor installation. And it owes its construction - an internal combustion pipe, thermal insulation and a second pipe made of stainless steel or aluminum. This chimney is convenient when the boiler is located in a place where it cannot be connected to an existing chimney or ventilation duct.

It happens that everything is done correctly and the end of the pipe is at the required height, but there is still no draft in it, the boiler plant cannot function normally. The reason may be simple: there is a taller structure next to your house, or the cottage itself has a complex multi-level shape and your gas flue has fallen into the zone of wind support.

But this, of course, is not the only argument in favor of the solution of such a chimney - it is so attractive that it can be made from an architectural element of a building block. Double-walled chimneys are fixed to the wall with clamps and console support.

It is also equipped with a drainage system and a condensate drainage system. At the top of such a chimney there is a so-called. a mouthpiece to be covered with a rain cap, and preferably a rotating chimney hood. They also have a very interesting design. This is because, in addition to the exhaust gas, they also supply the air necessary for the operation of boilers with a closed combustion chamber and condensation.

Calculating the wind pressure zone is very simple: draw an imaginary line from the highest point of the building to the ground at an angle of 45 degrees, as shown in the diagram.

In this zone arises high blood pressure and the traction will be very weak, the end of the shaft will have to be raised half a meter above the imaginary line. In order to avoid wind back pressure, regulatory requirements have also been written, according to which it is necessary to maintain an angle of 10º at a distance of more than 3 m from the ridge of the roof.

One of the main conditions is that the diameter of the chimney of a solid fuel boiler must be no less than the outlet for exhaust gases of the installation itself. Otherwise, there is a lack of gas duct throughput when the unit is operating at medium and maximum power, which is unacceptable. If the shape of the vertical shaft is rectangular, and the outlet for gases from the heater is round, it is necessary to compare them with each other in the area of ​​the flow area.

When connecting a solid fuel boiler, make sure that the length of the chimney at its outlet is at least two diameters before the first turn, and the latter is as small as possible along the entire length of the flue. Each turn creates additional flow disturbance and turbulence, causing increased local drag. Accordingly, the traction force deteriorates.

In order for the flow of gases passing through the circular cross-section of the chimney to flow smoothly into the vertical shaft, it is better to place the horizontal section from it to the heating installation at an angle. Ideally, this angle is 45º, however, this is not always possible, therefore a value of 30 or even 15º with an inclination towards the unit is acceptable. If the latter is equipped with a blower or a smoke exhauster, then the observance of the slope becomes not so important, since the combustion products are thrown out forcibly.

Conclusion

Parameters such as the height and size of the chimney for solid fuel boilers have great importance for their further comfortable operation. The best thing that can be done is to work out this issue at the stage of building design, in extreme cases - during construction. It will be more difficult to eliminate the consequences of flaws and will be more expensive

People need warmth - this is how nature works. V apartment buildings this problem is being addressed by the appropriate structures. When building a private house and outbuildings on a site, responsibility for the warmth and comfort is assigned directly to the owner himself, that is, many owners install a heating unit with their own hands and independently arrange a chimney for a solid fuel boiler.

For the full and safe operation of the boiler, it is necessary that the chimney is correctly installed (see Installation of chimneys). For example, a solid fuel boiler requires air to work, which must enter the equipment through special openings. After the fuel has burned out, the flue gases must be removed from the boiler. For this, there is a chimney for a solid fuel boiler. Let's figure out whether it is possible to implement a chimney for a solid fuel boiler with our own hands.

Chimney draft

Draft is the main parameter of the chimney. It reflects the speed of movement of flue gases. As you know, thrust arises due to the temperature difference (warm air rises) and the pressure difference in the room and outside, therefore, such parameters as the height and cross-section of the pipe directly affect the draft, this must be taken into account when planning the construction of a chimney with your own hands ..

Other properties of solid fuel boilers

The properties of heating units are unstable, this must be taken into account when planning to build a chimney for a solid fuel boiler with your own hands.

They are unstable because they directly depend on unstable factors: temperature of flue gases, air, direction and strength of wind, etc. Also, the properties of a solid fuel boiler are affected by the fact that the combustion of fuel in them is uneven. Thus, the temperature of the flue gas entering the chimney for a solid fuel boiler is not constant. In units powered by wood, it reaches 70-300 ° C, and in coal-fired boilers - 400–600 ° C.

It should be borne in mind that during the ignition of the boiler, the temperature rises sharply, and after the start of operation in standard mode, it decreases, and these factors also affect the intensity of the draft.

Parameters influencing the boiler operation

1. One of the important factors affecting the operation of the chimney of a solid fuel boiler is the height of the pipe, that is chimney length ... The explanation is simple: on straight sections, the flow of flue gases picks up speed. The cross-section and smoothness of the chimney walls are also important. Below are the parameters that are critical for effective work chimney:
   • To- absolute outside temperature;
   • g- acceleration of free fall;
   • Ti−average internal temperature (K);
   • A- cross-sectional area of ​​the pipe (m2);
   • h- pipe height (m);
   • Q- air flow, (m³ / s);
   • C- coefficient introduced due to friction (0.65–0.70).
2. Of no small importance is also chimney design for a solid fuel boiler. The fewer horizontal and narrowed sections, turns, the better the traction. This is explained by the fact that the flue gas flow rises along the pipe along a spiral path. Encountering obstacles on its way in the form of roughness, seams, etc., the flow changes direction, and gases are mixed.

Chimney temperature resistance

As already described above, the flue gas temperature can fluctuate within 70–600° C , therefore, the factor of heat resistance of the chimney is important. Today, various materials are used in the construction of chimneys, the best are steel, ceramics and refractory bricks. In very rare cases, glass chimneys are also installed.

Ceramic chimney

Ceramics is an excellent material if you are building a chimney for a solid fuel boiler (see Ceramic Chimneys for Chimneys). Ceramic flues have the following properties:

Chimneys for solid fuel boilers made of ceramics can be installed both indoors and outdoors.

Stainless steel chimney

Metal chimneys for solid fuel boilers are made of stainless and black steel (see Stainless steel sandwich chimneys). Products made of black steel are becoming less and less popular, as they are unstable to the effects of aggressive media: soot and condensation. Chimneys made of stainless steel contain additives of molybdenum, titanium, nickel and others chemical elements... For solid fuel boilers, steel 316, 316 L, 321 and some others are used. The composition of these grades of steel allows them to withstand temperatures up to 700–800° C ... A stainless steel chimney is a durable, reliable and inexpensive option.

Refractory brick chimney

Chimneys, pipes and other products made of this material can withstand temperatures up to 1000 ° C... Refractory bricks have a large set of positive properties, however, the manufacture of a chimney from this material for modern solid fuel boilers is undesirable. The walls of a brick chimney take a long time to heat up, which leads to the formation of condensation.

Chimney for a solid fuel boiler: installation rules

General Provisions

• Installation and installation of boilers must be carried out in strict accordance with the regulations and rules of fire safety.
• The optimal section and height of the chimney is selected in accordance with the instructions provided by the equipment manufacturer.
• The maximum length of horizontal sections should not exceed one meter.
• The chimney height is selected according to the manufacturer's recommendations (or should be no more than five meters).

When installing a chimney with your own hands, be sure to take into account that its device must allow condensate to drain, clean the pipes from soot and carry out maintenance.

Chimney connection rules

Chimney assembly

Systems of insulated and single-walled chimneys are assembled using the pipe-to-pipe method. In order to prevent tarry emissions and condensate from flowing into the pipe, the steel chimney is assembled using the "condensate" method. The vertical parts from the tee are also collected "by condensate", and the elements between the heating equipment and the tee are collected "by smoke".

When making the channel sleeve, a gap must be left. When using sandwich elements, rivets or self-tapping screws must be used to fasten them.

Chimney fixing

1. The fastening of single-wall chimneys is carried out at the rate of at least one fastening per one and a half meters. Fixing sandwich chimneys requires fixing each element. If the height of the pipe is more than one and a half meters above the level of the roof, it is necessary to install a brace.
2. The final stage of the do-it-yourself installation is the installation of a deflector or fungus on the top of the chimney pipe.

Before you start operating a self-assembled chimney for a solid fuel boiler, it is better to additionally check that everything is properly prepared: the protective film must be removed and the gate open.