Chimney for the oven with your own hands

The furnace chimney can be built by hand if there is a masonry scheme at hand, and the home master has at least minimal skills in the mason's work. The erection of this department requires no less serious approach than the construction of the furnace itself, since the quality of its masonry will depend on the efficiency of heating, the safety of those living in the house, the total lifetime of the entire heating installation.

Working on the chimney, it must be remembered that its internal surfaces must be as neat and smooth as the external ones, since this factor directly affects the creation of good traction.

Types of brick chimneys

Chimney pipes are divided into types, depending on the location of their installation relative to the furnace itself. So, they are indigenous, nasadnye and wall.

• The most common design of a brick chimney is the embedment. It is installed directly on top of the heater and is its continuation.

• The second most popular is the chimney. This type of pipe differs in that it is installed next to the furnace or enters into its structure and is placed on one of its sides.

Indoor pipes can be installed for both brick and cast iron furnaces. In addition, one basic construction is often used for several heating appliances. For example, in a two or three-story house, one chimney is passed through all the floors and the stoves are connected to it. If it is planned to use the pipe in this way, then in this case, accurate calculation of its parameters must be made, otherwise there will be no normal draft, which means that the efficiency of the furnaces will decrease, and the risk of penetration into the rooms of combustion products increases.

• The wall pipe is built into the main internal or external walls. But, in the latter case, the walls of the chimney will have to be very well insulated, since due to the large difference in external and internal temperatures, condensate will actively collect inside the channel, which will significantly worsen the operation of the furnace, reducing the draft and facilitating the rapid growth of the chimney by soot.

It should be noted that although this design is highlighted in a separate view, it can be either root or crocheted.

Construction of a brick chimney pipe

Chimney has several sections. To understand its basic construction, as an example, you can take the structure of the pipe, as most often it is chosen by the engineer-engineers, composing the scheme-ordering furnaces.

So, the design of the casing pipe with its passage through the attic ceiling and truss system, includes the following departments and elements:

1 - Metal cap or umbrella. It can have a variety of forms, but its function is always to protect the internal space of the chimney from the penetration of atmospheric precipitation of various types, as well as dust and dirt.

2 - The pipe head consists of outward-facing bricks that will protect the neck of the structure from rain drops that will flow down the protective cap. The metal umbrella is fixed, including, and on the protruding parts of the head.

3 - Pipe neck.

4 - The cemented or otherwise waterproofed inclined surface of the otter, designed to remove water from the neck of the pipe.

5 - Otter. This part of the design has thicker walls than the neck of the tube. The otter should be located at the passage of the chimney through the rafters and the roof. Thick walls of the otter will protect the combustible materials of the crate under the roof from overheating.

6 - Roofing material.

7 - Trimming of the rafter system.

8 - Rafters.

9 - Pipe stand. This department is in the attic of the house.

10 - Folding. This part of the chimney begins under the ceiling inside the house, passes through the attic and ends in the attic, just above or level with the beams overlapping. The flap, just like the otter, has thicker walls than the neck and riser pipe. The increased thickness also protects wooden beams and other combustible materials of attic or interfloor overlapping from overheating.

It should be noted that in some cases instead of firing in its place around the pipe mounted metal box, filled with non-combustible materials, such as sand, vermiculite or expanded clay. The functions of this interlayer, having a thickness of 100 ÷ 150 mm, are also the protection of combustible overlap materials from overheating.

11 - Beams overlap.

12 - Insulation, which is most often made from asbestos, is in any case necessary for creating fire safety, since the walls of the chimney will come into contact with the wood of the joists and other materials, of which the ceiling and ceiling consist.

13 - Smoke damper located in the room at the top of the pipe, allowing to regulate the intensity of the diverted streams of heated air and combustion products.

14 - The neck of the pipe, which starts at the top of the furnace - is overlapped.

Calculations of parameters of a chimney

The principle of operation of a chimney system consists in the movement of air masses from the combustion chamber to the outlet to the street, that is, from the lowest point to the upper one. This process occurs through the creation of a thrust that arises in connection with temperature and pressure drops. It is thanks to all these factors and the normal functioning of the chimney system.

To create optimal aerodynamic processes, the pipe channel size should correspond to the capacity of the furnace, which, in turn, largely depends on the size of the furnace. Surfaces of the internal chimney space must have smooth walls, through which air flows will slide freely without turbulence, and thanks to this, there will be no reverse thrust. That is why often enough a brick square flue is built in a tab of a round ceramic pipe, which has an absolutely smooth surface and does not have internal corners.

Size in section

In connection with these factors, it is necessary to carefully calculate the internal size of the chimney, taking into account its length, since the larger this parameter, the higher the thrust in the pipe.

The matching of the parameters of the chimney passage and the power of the boiler, as well as the size and number of channels provided for by the design and passing inside the furnace, is of great importance for the creation of normal thrust and the high-quality functioning of the appliance.

If the parameters of the internal dimensions of the chimney in the section exceed the calculated value, this will lead to a rapid cooling of the heated air in it and the appearance of condensation, and hence to a reduction in thrust. In this case, the necessary balance will be disturbed, and the streams cooling at the top of the pipe can return downward, creating smoke in the room.

The size of the chimney hole is calculated as follows:

• The size of the fireplace chimney with an open firebox approximately corresponds to the proportions 1:10( section of the chimney( f) / area of ​​the furnace window( F)).This formula as a whole acts both for square or rectangular, and cylindrical type of pipe, but not directly, but taking into account the shape of the channel section and the overall height of the chimney.
• The chimney diameter of the furnace with a closed combustion chamber is proportions of 1: 1.5.In the case where the heat transfer of the heating plant is less than 300 kcal / h, the cross-section usually has a size of 130 × 130 mm or half-brick( not less).When carrying out calculations, it must be taken into account that the size of the flue duct section must not be less than the inlet of the blast furnace.

When calculating a chimney chimney, you can use the following table.

height pipe H, m	5	6	7	8	9	10	11
ratio f / F in%
pipe cross section	Cylindrical	11.2	10.5	10	9.5	9.1	8.7	8.9
Square	12.4	11.6	11	10.5	10.1	9.7	9.4
rectangular	13.2	12.3	11.7	11.2	10.6	10.2	9.8

Note the direct dependence of the flue duct section not only on the parameters of the furnace, but also on the height of the pipe. Probably, sometimes in calculations it will be more reasonable to start from this parameter. For example, it would be absolutely ridiculous to look like a pipe 11 meters high on a single-story country house.

The same dependence, but more accurately presented in the form of a graph.

Let's assume that it is necessary to calculate the section of a chimney for a fireplace with a firebox whose window dimensions are 500 × 700 mm, ie the total area is 0.35 m² .It is assumed that a pipe with a total height of 7 meters is permissible on the building.

• We look according to the graphic scheme:

- for the circular section of the chimney optimal ratio f / F = 9,9% ;

- for square - 11.1% ;

- for rectangular - 11,7% .

• It is easy to calculate the optimum chimney duct section area:

- circle: 0,35 × 0,099 = 0,0346 m² ;

- square: 0,35 × 0,11 = 0,0385 m² ;

- rectangle: 0,35 × 0,117 = 0,041 m² .

• Now, using the simplest geometric formulas, it is easy to reduce the area to linear dimensions:

is the diameter of a round pipe: d = 2 × √S / π = 2 × √0.0346 / 3.14 ≈ 0.209 m = 210 mm .

- side of a square pipe: a = √S = √0,0385 ≈ 0.196 m = 196 mm .

- the rectangle can have different variants - for example 0,130 × 0,315 m or 130 × 315 mm .

Of course, these dimensions are obtained for reference, and usually "tied" to the standard pipe diameters or brick dimensions.

Chimney height

The height of the pipe has already been mentioned above, but there was a calculation from the already known value. And what should be the optimal height?

To calculate the height of the chimney, you must also take into account several factors. Hot air passing through the internal channels of the furnace and chimney, leaving it, immediately cools down, which means that the longer it will be inside the channels, the longer the heat will stay in the oven.

Correctly selected pipe height contributes to the normalization of the thrust and at the same time - longer heat preservation inside the structure. So, if the pipe is lifted a little higher than required by calculations, the draft can increase to such an extent that the heat does not stay in the furnace for a long time, which means that it will not have time to warm up and give heat to the rooms. In this connection, it is necessary to put fuel all the time, which will make the furnace work extremely uneconomical. Well, too low a pipe can lead to the creation of a return draft system inside the system, which will provoke the ingress of carbon monoxide into the living rooms. The same phenomenon can also occur when the section of the chimney internal channel is inconsistent with its height.

According to the existing rules, the height of the pipe( or, more precisely, the vertical distance from the grate to the mouth of the chimney) can not be less than 5 meters.

The height of the chimney above the roof is usually calculated separately, taking into account such parameters of the structure of the house structure as the angle of the roof slope, the thickness of the roofing and the distance between the chimney and the ridge of the roof. All calculations are carried out without taking into account the height of the protective umbrella( cap) covering the pipe from above.

If the chimney is not properly installed on the roof, then turbulence of warm air will appear at the outlet, which will significantly reduce the draft. Therefore, the chimney must be raised above the plane of the roof, taking into account certain rules that relate to the level of its outlet with respect to the ridge line:

• If the pipe leaves the roof at a distance of 1500 mm from the ridge, its height above itshould be not less than 500 mm.
• If the pipe leaves the roof at a distance of 1500 ÷ 3000 mm from the ridge, then it must be raised to its level.
• In the event that the chimney pipe passes through the roof over a distance of more than 3000 mm from the ridge, its upper cut must be on a conditional line drawn at an angle of 10˚ from the horizontal from the top point of the ridge.

Nevertheless, no matter at which distance the chimney from the ridge is located, it should rise above the roof not less than 500 mm. This also applies to flat roofs.

It should be noted that the chimney is a serious engineering structure, and it is quite difficult to independently envisage all the nuances of its construction. Therefore, for the furnace to function properly, it is recommended to use the services of a specialist, computer programs or ready-made schemes. Usually, the masters place their development-orders, which already indicate the optimal dimensions of the chimney channels. And there should not be any independent activity in such matters.

How to choose the "right" brick for masonry chimney?

To ensure that the constructed pipe lasts a long time, and the brick does not break down from the temperature drop and the influence of external environmental influences, it is necessary to choose this material correctly. In addition, reliable brickwork must provide complete fire safety for the combustible materials surrounding the chimney.

. According to its main characteristics, the brick must be full-bodied, fire-resistant and fired.

For the construction of a chimney, the brick is selected according to its grade, which is determined by the level of firing, and is divided into three categories:

• grades I is a moderately burnt building material.

A qualitative, well-fired brick of the first grade has the following characteristics:

- The color is bright red or with a slight yellow tinge.

- Good clay density.

- Smooth without traces of crumbling fins and smooth surfaces without scoring.

- When tapping a high-quality brick with a hammer, it should produce a sufficiently sonorous sound.

• II grade - unbaked brick, can be characterized as follows:

- Color pale orange unsaturated.

- Low frost resistance, density and heat capacity.

- High porosity.

- When tapping this brick gives a deaf short sound.

- On the surfaces of bricks of the second grade there may be small scuffs, its edges may have crumpled areas.

• III grade - burned brick. This material has the following special features:

- Has a deep deep red, down to brown.

- Not frost-damp.

- The structure of the brick is dense, but porous.

- High thermal conductivity.

- Durable for compression, but fragile and does not withstand other loads.

- Its edges can be crushed, and the surfaces have chipped.

- Sound when tapping is very sonorous.

From the presented characteristics it can be concluded that a first-grade brick with the marking M150 ÷ ​​200 is suitable for a chimney. Unburnt material is recommended to be completely excluded from the chimney masonry, and the burned material can be used for foundation work when erecting a chimney.

Before using the brick in for masonry, some stoves soak it in water, while others use dry. Dry brick will absorb moisture from the mortar, which will make the masonry less durable, and the strewed soaked material will dry longer. Therefore, each master chooses his own technology and the most convenient method of work for himself.

Making mortar for masonry

It is very important to choose not only the correct brick for the construction of the chimney, but also the mortar for its masonry, since the seams of this structure must be absolutely sealed and resistant to external influences.

Differences in solutions depending on the masonry area

This diagram shows the areas of the stove construction, by which you can determine which solution is used in each of them.

can be used in different parts of the oven. Since only the flue is considered to be a chimney, it is necessary to determine the solution used in zones numbered 7 to 11. If the furnace has a core type pipe, zone 3.

• So, zone number 3 are the first two rows of the root type chimney, which are laid on a concrete foundation and are under a clean floor. Since these rows are the basis of the masonry of the whole structure of the chimney, they must have sufficient strength and resistance to high loads. Therefore, sand-cement mortar is used for their laying, which is kneaded in proportions of 3: 1 or 4: 1.Some stoves prefer to add ½ pieces of lime, which will make the mixture more plastic.
• Zone No. 7 - these are the first two rows of a casing pipe, which are located directly above the furnace. This area is called the source of the chimney, the temperature in it reaches 355 ÷ 400 degrees. The laying of the source is carried out on a clay-sand mixture.
• Zone number 8 - the flue pipe of the chimney is located in the living room under the ceiling, before the passage of the structure through the attic floor. Sometimes this element of construction can cover the passage itself, but ends in an attic space. The temperature in this region can reach as high as 355 ÷ 400 degrees, so the clutch is also produced on clay-sand mortar.
• Zone number 9. For this area, you can use sand or expanded clay, as well as clay-sand mortar. This zone of the pipe is called the cutting and serves to protect the combustible materials of the overlap from overheating. To create the cutting, a metal box is built around the pipe, and then it is filled with one of the selected materials. Another variant of the cutting is the thickening in this place of the pipe walls.
• Zone number 10 - the neck of the pipe is in the attic space and goes outside, therefore it experiences great loads from temperature changes and the influence of external factors. For this section of the pipe, sand-clay mortar with the addition of cement is most often used.
• Zone number 11 - the chimney head is laid out from the same solution as the neck of the pipe, or simply using a cement-sand mixture.

Composition of masonry furnace solutions

The solution materials must be well cleaned of various impurities. Clay is taken medium grease, sand washed and sifted, lime - necessarily hydrated. Cleaning of dry clay and sand is carried out by sieving through a sieve made of a mesh having 1 × 1 mm cells. Clay can be cleaned and after it is soaked by rubbing it through the same sieve. This method of cleaning is faster and more efficient.

The approximate formulation of the various solutions is given in the table:

Solution types	Clay mortar	Lime mortar	Cement mortar
Used materials	Material consumption in parts
Sand	4	2,5	3-4
Clay clay	1	-	-
Conventional clay	1	-	-
Lime	-	1	-
Cement M400	-	0,5	1

As the clay-sand mortar is the main one for laying the chimney, its preparation is worth considering in more detail.

. Before mixing the solution, the cleaned clay needs to be prepared. It is soaked and mixed well until homogeneity, it must be infused and swollen, having absorbed water. This process will take 12 ÷ 14 hours. The soaked mixture is periodically mixed and, if necessary, water is added thereto. At the final stages of soaking and mixing, sand is added to the clay, according to the proportions. Mixing of ordinary clay solution is carried out in proportions 1: 2, 1: 3 or 1: 4 - this parameter depends on the fat content of the clay, the fatter it is, the more parts of sand it is added to.

It is recommended to test various proportions of the solution - to make prototypes - balls or strands, and see which one will be the most stable after drying. Based on the results of such an "experiment" and you can choose the optimal ratio of ingredients.

The solution should have a uniform consistency, without lumps and impregnations, be ductile and easily slip off a clean metal spatula.

The masonry mixture is applied to the brick with a layer 8 ÷ 9 mm thick, and when it is pressed with the top brick, a seam of 6 ÷ 7 mm should be formed.

Flue stacking

The laying of the chimney starts from the blocking of the furnace, and the chimney is from the foundation, which is laid out on the same principle as the base for the heating installation.

It should be noted that the order of the chimney is not as complicated as the masonry scheme of the furnace itself, so it will be easy to understand.

Different versions of chimneys can differ and the number of rows, and design features. Masonry is always made with bandings of rows.

Below in the tables one of the variants of laying of the chimney as the most common one, with its passage through the attic and through the roof, will be considered.

The order of the

• chimney laying The first stage is the erection of a chimney from the furnace to the roof.

Illustration	Brief description of the operation
	The first two rows of the neck of the chimney, each consisting of five bricks, must be executed neatly and perfectly evenly, as they set the direction and evenness of the remaining rows of the structure.
	The same way all the rows of the neck of the chimney are laid out. The number of rows in each case may be different, but this part of the pipe must be completed in two rows before it passes through the attic.
	Next, there is a flare of the chimney. It can also consist of a different number of rows - from two to four. Each of the rows of the pile is placed with a ledge outward at 30 ÷ 35 mm, which results in a step-like construction expanding to the ceiling. Despite the fact that this section of the pipe extends to the outside, the internal chimney remains in its original dimensions.
	In the picture presented above, it is possible to consider the cross-section of the neck of the pipe before the firing.
	This shows the first row of the fretboard, which does not reach the floor surface of the attic in one row. It already consists of 6 solid bricks, two halves( brick is divided across), 2 halves( brick is divided along) and 2 quarters.
	The next row, also entering the fir-tree, leads the chimney to the level of the attic floor, with a non-flammable gasket made between the brick and the flooring materials( usually using asbestos sheets cut into strips). This series consists of the same number of bricks as the previous one.
	The next row of fretting is the widest in section, and its extreme bricks reach the surface of the attic floor, approximately 30 to 35 mm. This series consists of 12 whole bricks and 3 halves.
	1 row of riser is stacked on top of the flap. Its length and width are returned to the original size of the pipe, and it is laid out of 5 bricks.
	Further, in the roof, a hole is cut out and cut through which the chimney will exit to the street. To accurately mark the hole for the passage of the pipe, you should use a plumb line. The hole is cut using the most convenient tool, for example, jigsaw.
	When the hole for the passage is ready, the chimney flue is completely laid out, each of the rows of which consists of five bricks. Mandatory strict control of the verticality of the masonry.

• Stage of the second - passage through the roof and the pipe head.

Illustration	Brief description of the operation
	The last row of the riser is laid out half the brick above the lower part of the roof slope in the cut out hole. A gasket made of asbestos strips is made between the masonry and the roofing material, as well as the crate.
	The next step is the first row of the chimney department, called the "otter", which has an expanded size, compared to the riser. Front of the row - the bricks extend forward, overlapping the lower side of the bore. This series requires 5 whole bricks, 1 half, 1 part ¾ bricks, 1 part - ¼ brick, that is, one of the bricks can be divided into ¾ and ¼ pieces.
	The second row of the "otter". The size of the outer section of the pipe becomes larger by increasing it in the front. The front two bricks extend forward and in the lateral sides at 30 ÷ 40 mm above the previous row. For this stage 5 whole bricks, 3 halves and one brick are divided into ¼ and ¾ pieces.
	The next two rows are laid out according to the configuration of the previous one, but with a bandage of bricks.
	The fourth row of "otter" is laid with a ledge at the rear of the section - it hangs over the roof and overlaps the joint between the brick and the roofing material. For this series, 8 solid bricks are used, 2 parts are ¾ brick and ¾ of brick is divided into two parts along.
	Next, laid out the first row of the neck of the chimney. The series consists of five bricks that move inside the masonry to 80 ÷ 90 mm, that is, everything returns to the original perimeter of the outer section. Further, in the same order, with a bandage of rows, the neck of the chimney rises to the desired height, taking into account the fact that the headline consisting of two rows will also be laid out.
	The next stage is the first row of the head. It is laid out with a ledge outward at 30 ÷ 40 mm, and thus will be one of the protective elements of the neck of the pipe from precipitation. The series consists of 5 solid bricks, 1 piece of ¾ brick, 2 pieces of ¼ brick, 6 halves of bricks cut along.
	The final row of the head, consisting of 5 bricks, is laid out with a shift inward to the same 30 ÷ 40 mm. The protrusion of the previous row is closed with a concrete solution with a slope to the outside. This protrusion and the last row will be secured protecting from getting into the chimney duct of sediments and debris cap.
	From the side of the construction of the chimney, passing through the attic ceiling, the roofing system and the roofing material will end up looking something like this.

After the laying of the pipe itself, a waterproofing must always be arranged around the roof, which will seal the joints between the walls of the chimney and the roofing material. One of the variants of this passage is shown on the attached video:

Video: How to insulate the passage of a pipe through the roof of the "ondulin"

In conclusion, it must be said that the masonry of the chimney itself is quite feasible even for the beginner, but when working at height,security. Of course, it is better to build a chimney along with a reliable helper who can not only give an expert advice on the implementation of the masonry, but also provide the necessary insurance.

Video: Demonstration of the basic tricks of laying brick pipe