What should be the height of the chimney relative to the roof ridge. How high should the chimney be?
Installing a chimney, it is very important to calculate the correct flue diameter, this issue should be given special attention when designing autonomous system heating. Often the chimney is selected based on approximate parameters. Many ordinary people believe that it would be better to make the diameter of the chimney section larger, but this is not at all the case. In order for the heating system to function optimally, an accurate calculation of the diameter of the chimney is required.
Initial parameters calculation of the chimney pipe.
To calculate the chimney, you can use the chimney calculation calculator.
The characteristics of the future chimney are directly affected by certain parameters, of which the most important are:
1. Type of heater. The organization of a gas exhaust system is in most cases necessary for solid fuel boilers and furnaces. The calculation takes into account the volume of the combustion chamber, as well as the area of the opening of the chamber for air entry into the furnace - the ash pan. Often the calculation is also made for home-made boilers that run on diesel fuel or gas.
2. The total length of the chimney and its configuration. The most optimal design is considered to be 5 meters long and with a straight line. Additional swirl zones that negatively affect traction are created by each turning angle.
3. The geometry of the chimney section. The ideal option is a cylindrical chimney design. But this form is very difficult to achieve for brickwork. A rectangular (square) section of the chimney is less effective, but it will also require less labor.
Approximate and accurate calculation of the diameter of the chimney.
Precise calculations are based on a complex mathematical platform. To calculate chimney diameter, you need to know its main characteristics, as well as the characteristics of the fuel and the heating device. For example, we can take the calculation of a standard pipe with a circular cross section without rotary nodes, connected to a stove and running on wood. The following calculation input parameters are taken:
- gas temperature at the entrance to the pipe t- 150 ° C;
- the average speed of passage of gases along the entire length - 2 m/s;
- firewood (fuel) burning rate at one bookmark B= 10 kg/hour.
Following these data, you can go directly to the calculations. First you need to find out what volume of outgoing gases, it is determined by the formula:
Where V is the volume of air required to maintain the combustion process at a rate of 10 kg/h. It equals - 10 m³ / kg.
Substituting this value, we get the result:
Then we substitute this value into the formula, according to which chimney diameter is calculated:
To make such a calculation, you need to know exactly all the parameters in the future gas exhaust system. This scheme is very rarely used in practice, especially in the case of organizing a household autonomous heating system. Determine the diameter of the chimney possible in other ways.
For example, based on the dimensions of the combustion chamber. Since the amount of fuel burned depends on its size, the volume of incoming gases also depends on it. If an open firebox and a chimney with a circular cross section, then the ratio is 1:10. That is, when the size of the combustion chamber is 50 * 40 cm, then the optimal diameter of the chimney will be 18 cm.
When erecting a brick chimney structure, the ratio is 1: 1.5. Chimney system diameter in this case, it should be larger than the size of the blower. The square section will be at least 140 * 140 mm (this is due to the turbulences created in the brick pipe).
Swedish method for calculating the diameter of a chimney.
In the examples described above, the height of the flue system is not taken into account. For it, the ratio of the area of \u200b\u200bthe combustion chamber to the cross section of the pipe is used, taking into account its height. The value of the pipe is determined according to the schedule:
Where f is the area of the chimney and F is the area of the furnace.
However, this method is more applicable to fireplace systems, since the volume of air for the furnace is not taken into account.
You can choose different methods for calculating the diameter of the chimney, but when installing complex heating systems, an optimally accurate circuit is important, especially for low-temperature long-burning heaters.
7975 0 2
How to make a calculation chimney – 4 important points things to consider when installing a chimney
For heating private houses in the cold season, they are most often used, either conventional brick ovens and fireplaces, or household heating boilers on solid, liquid or gaseous fuels. An indispensable condition for the normal operation of such heating appliances, is the free flow of a sufficient amount of fresh air into the flame combustion zone, and the rapid removal of spent fuel combustion products into the atmosphere. To ensure compliance with these conditions, before installing the stove chimney, it is very important to perform a competent calculation of the chimney with natural draft, since not only the efficiency of the heating devices, but also the safety of the residents of a private house will depend on this.
Due to what natural draft is formed in the furnace
Most heating and cooking stoves and boilers autonomous heating are not equipped with a system of forced fresh air intake and removal of exhaust flue gases, so the process of fuel combustion in them directly depends on the presence of natural draft in the chimney pipe.
Theoretically, the method for calculating the chimney is quite simple. To make it clear to the reader where natural thrust comes from, then I will try to briefly explain the physics of thermal and gas-dynamic processes that occur in the furnace during fuel combustion.
- The furnace chimney is always installed vertically (with the exception of certain horizontal or inclined sections). Its channel starts at the top of the firebox vault, and ends on the street, at some elevation above the roof of the house;
- Hot flue gases in the fuel combustion zone have a very high temperature (up to 1000 ° C), therefore, according to the laws of physics, they quickly rush upwards;
- Rising up the chimney at a speed of about two meters per second, the flue gases create an area in the furnace reduced pressure;
- Due to the natural rarefaction in the furnace, fresh air is supplied through the blower and the grate into the flame burning zone;
- Thus, it is easy to understand that for the formation of good natural traction, several conditions must be met at once:
- The chimney must be located strictly vertically. In addition, the ode should be of sufficient height and as straight as possible, without unnecessary bends and turns at an angle of more than 45 °.
- The internal section of the smoke channel must be designed in such a way that it allows the entire volume of flue gases that are formed during the combustion of fuel to freely pass into the atmosphere;
- In order not to create significant aerodynamic resistance to the movement of smoke, the inner walls of the pipe should have the most even and smooth surface with a minimum number of transitions and joints;
- As you move along the pipe, the flue gases gradually cool down, which leads to an increase in their density, and a tendency to form. To prevent this from happening the chimney pipe must be well insulated.
A significant positive effect on the force of natural traction is exerted by the wind on the street. This is due to the fact that a continuous flow of air directed perpendicular to the axis of the chimney creates a reduced pressure in it. Therefore, in windy weather, good draft in the furnace is always observed.
Moment 1. The choice of material and design of the chimney
The normative and technical construction documentation does not stipulate any strict requirements for the arrangement of furnace chimneys, so each homeowner makes a chimney at his discretion. At the same time, I must say that all types of chimneys differ from each other not only in terms of design and external features, but also in terms of heat engineering, weight and gas-dynamic characteristics.
- The masonry chimney is characterized by high strength and durability, it can withstand long-term exposure to high temperatures, but it is poorly resistant to aggressive smoke condensate. Due to the massive brick walls, it has a high heat capacity and satisfactory thermal insulation properties. Concerning the issue of water vapor condensation and gas dynamics brick chimney, then not everything is so good here.
- massive brick pipe has significant weight, therefore, its installation requires its own foundation, which, in turn, also requires separate calculations;
- The rectangular or square cross-sectional shape of the flue ducts, combined with uneven and rough inner walls, create significant resistance to the movement of flue gases, so the cross section of such chimneys should be selected with a small margin;
- Lack of additional thermal insulation can lead to condensation inside the chimney, therefore, its walls must be of sufficient thickness so that the temperature of the flue gases inside does not fall below the dew point.
- Asbestos-cement and ceramic pipes are sold ready-made and are easy to install with your own hands, so they are often used in the construction of private houses to connect gas or solid fuel boilers. Many homeowners are attracted by their not very low price, but I want to remind you that when installing a chimney from asbestos-cement pipes, the following points should be taken into account:
- Asbestos-cement pipes have high thermal conductivity and do not retain the heat of flue gases well., due to which condensation can form inside, which will quickly lead to the destruction of the walls;
- To prevent this from happening, when installing an asbestos-cement chimney, it is important to choose the right heat-insulating material and calculate its thickness so that the temperature of the flue gases at the outlet does not fall below 110 ° C;
- At temperatures above 350°C, asbestos cement can crack and break down, therefore, between the chimney inlet and the boiler outlet, I advise you to install a distance spacer made of insulated metal pipe;
- Its length should be calculated in such a way that the temperature of the flue gases at the inlet to the asbestos-cement pipe does not exceed 300-350 ° C;
- Asbestos-cement pipe, in itself, has sufficient rigidity. Despite this, for better thermal insulation and protection against mechanical damage, I recommend installing such a chimney inside a protective jacket made of brickwork half a brick thick.
- Stainless steel metal sandwich pipes, in my opinion, are the most successful option for a home chimney, which is equally well suited for both a massive brick slab and a modern compact heating boiler. They are recruited from separate sections, so they allow you to make an external or internal chimney of almost any configuration with your own hands.
- The inner sleeve made of heat-resistant stainless steel has a perfectly smooth surface and a round cross-section, therefore creating a minimum aerodynamic resistance to the flow of flue gases. For this reason, the internal diameter of the smoke channel must correspond to the minimum value of the design characteristics;
- Insulated metal sandwich pipe has good thermal insulation properties, and does not need additional insulation, therefore, heat engineering calculations, in this case, are not necessary;
- When installing and assembling the chimney, each section must be mounted in such a way that it is attached to the inner wall or facade of the building at least in two points. In this case, the distance between the mounting brackets should be no more than 1200 mm.
- Prefabricated insulated ceramic chimneys have similar characteristics, and can also be used almost without restrictions, in combination with any type of stove, fireplace or domestic heating boiler.
- They are designed and manufactured in the factory, in compliance with all necessary thermal calculations and the requirements of the rules. fire safety;
- This makes it possible to mount them in the form in which they are, without thinking about your own additional calculations;
- Despite this, I want to remind you that such a sandwich made of expanded clay concrete blocks, mineral wool insulation and a ceramic pipe insert, as an assembly, can have a lot of weight, so it is also necessary to calculate and make a separate foundation for it.
- Recently on the market building materials started to appear the new kind polymer chimneys, better known under the trade name "Furan Flex". It is a flexible reinforced sleeve that is installed in an existing smoke channel and then filled with hot steam under high pressure. under pressure and high temperature the sleeve straightens and polymerizes, as a result of which it completely fills the lumen of the smoke channel, and strengthens the pipe walls from the inside.
- Installation of such a polymer insert requires the use of special equipment. and strict observance of technological regimes, therefore, it can be performed exclusively by qualified specialists;
- Based on this, in this case, I do not recommend hammering your head complex formulas, and entrust the performance of all calculations to the engineers of the contracting organization that will perform the installation.
The asbestos-cement pipe has a rough inner surface, which contributes to the rapid adherence of soot and soot. Over time, the growing layer of soot reduces the internal sectional area and increases the aerodynamic resistance of the smoke channel, so I do not recommend using such pipes for stoves and boilers for solid and liquid fuels.
Moment 2. Calculation of the inner diameter of the chimney for solid fuel stoves and fireplaces
In order to perform a correct calculation of the chimney draft, it is first necessary to determine the required internal cross-sectional area. In this section, I will tell you how this is done, using the example of calculating the cross section of a chimney for heating stoves and solid fuel fireplaces.
- First of all, it is necessary to determine what volume of flue gases will be produced when a certain type of fuel is burned in a furnace in one hour. Such a calculation is performed according to the following formula:
V gas \u003d V * V fuel * (1 + T / 273) / 3600, where
- V gas- the volume of flue gas that will pass through the pipe in one hour (m³ / hour);
- B- the maximum mass of fuel that burns within one hour in the furnace (kg);
- V fuel- coefficient of the volume of flue gases that are emitted during the combustion of a certain type of fuel (m³ / kg).
- This value is determined according to special tables, and its value is: for dry firewood and lumpy peat - 10 m³ / kg, for briquetted brown coal - 12 m³ / kg, and for hard coal and anthracite - 17 m³ / kg;
- T– flue gas temperature at the outlet of the pipe (°C). With a normally insulated chimney, its value can be from 110 to 160°C.
- Having the obtained value of the total volume of gas passing through the pipe per unit time, it will not be difficult to calculate the required cross-sectional area of the chimney channel. It is defined as the ratio of the received volume to the flue gas velocity, and is calculated using the following formula:
S smoke = V gas / W, where
- S smoke- cross-sectional area of the smoke channel (m²);
- V gas- the volume of flue gases per unit of time, which we received in the previous formula (m³ / hour);
- W is the reduced velocity of the upward movement of the gas-smoke flow inside the pipe (m/s). Here I must say that this is a conditionally constant value, and its value is 2 m/s.
- In order to understand what pipe diameter we need to make a chimney, based on the obtained value of the circle area, we need to determine its diameter. For this, the following formula is applied:
D = √ 4 * S smoke / π, where
- D- the inner diameter of the round chimney pipe (m);
- S smoke- the area of the internal section of the chimney obtained in the previous calculations (m²)
To make it clear to the reader, I propose to consider a simple example of calculating a chimney for a stove, if it is known that during heating, 8 kg of dry firewood burns in it per hour, and the temperature of the flue gases at the outlet is 140 ° C.
- According to the first formula given, we determine the maximum amount of smoke that can be released in one hour of burning 8 kg of dry firewood: V gas = 8 * 10 * (1 + 140 / 273) / 3600 = 0.033 m³/hour;
- According to the second formula, you need to calculate the required cross-sectional area of the smoke channel: S smoke = 0.034 / 2 = 0.017 m²;
- The last formula allows you to determine the desired diameter of the pipe, based on the known area of \u200b\u200bits cross section: D = √4 * 0.017 / 3.14 = 0.147 m;
- Thus, we determined that for this furnace, a chimney with an inner diameter of at least 150 mm is required for the bath.
If during the calculations you get a non-integer number, then I advise you to round it up to an integer value, but such rounding is allowed within reasonable limits, because in this case, a very large diameter does not mean very good.
Moment 3. Calculation of the chimney pipe for domestic boilers
In this article, I deliberately did not give separate calculations for factory-made household solid fuel and gas boilers, since any instruction for the use of boiler equipment already contains all the necessary technical information.
Knowing the passport thermal power your his gas boiler, the diameter of the chimney is easy to choose, in accordance with pre-calculated parameters.
- For small heating boilers with a maximum heat output of not more than 3.5 kW, pipes with an inner diameter of 140-150 mm will suffice;
- For household boiler equipment of medium power (from 3.5 to 5 kW), chimneys with a diameter of 140 to 200 mm will be required;
- If the power of the heating boiler is from 5 to 10 kW, then pipes with a diameter of 200 to 300 mm will need to be used for it.
If the gas boiler is equipped with a built-in turbine to create forced draft, then the diameter of the exhaust pipe can be much smaller than the above values. In this case, the recommended pipe size must be indicated in the product data sheet.
Moment 4. Determining the height of the pipe and the location on the roof
The strength of natural draft largely depends on the height difference between the level of the grate of the firebox in the lower part of the furnace, and the wind deflector or the mouth of the smoke channel in the upper part of the chimney.
In order for the heated flue gases to use their energy as efficiently as possible to create natural draft, it is very important to correctly calculate the height of the chimney relative to the grate and relative to the roof ridge.
- The relative height of the furnace chimney, from the level of the grate to the mouth of the chimney, must be at least 5000 mm;
- On residential buildings with an exploitable flat roof, the mouth of the chimney must be located at least 500 mm higher than the maximum height of the side parapet or roof railing;
- On houses with a gable or hip sloping roof, the mouth of the chimney must be located no lower than 500 mm from the level of the roof ridge;
- If on a sloping roof the chimney is located on one of the slopes, at a distance no further than 1500 mm from the roof ridge, then it must also rise 500 mm above the level of the ridge;
- In the event that this distance is from 1500 to 3000 mm, the smoker's wind deflector can be located at the level of the roof ridge;
- On gently sloping roofs with a small slope angle, the chimney can be located at a distance of more than 3000 mm from the ridge. In this case, its optimal height is calculated in accordance with the diagram in the figure below.
Not right choice the height of the pipe or its location relative to the roof ridge, with an unfavorable wind direction, it can cause the formation reverse thrust. This phenomenon is very dangerous, since it can lead to the release of burning coals and poisonous carbon monoxide from the blower or firebox into the living space.
Conclusion
Summing up, I want to note that when choosing materials, dimensions and configuration of the chimney, first of all, one should proceed from the maximum heat output of the heater. At the same time, you also need to take into account your financial capabilities, and what types of fuel your stove or heating boiler is designed for.
You can learn more about all the described types of chimneys from the attached video in this article, and if you have any questions or comments, I suggest discussing them in the comment form.
When installing systems furnace heating it is necessary to carry out design, which includes the calculation of the chimney on the basis of SNiPs and other regulatory documents.
Basic rules for the operation of heating equipment
Let us immediately denote that one stove can be used for heating no more than three rooms located on the same floor. In multi-storey private houses, multi-tiered stoves are allowed, and each should have a separate channel and firebox.
Not allowed:
- installation of forced exhaust ventilation without arranging the corresponding supply air;
- the use of ventilation ducts for the removal of combustion products, and not chimneys.
The stove may have a smoke channel located in the outer wall, the installation of which is carried out from various, as a rule, stone non-combustible materials.
Also, the chimney is installed using root or mounted chimneys.
Each stove must have its own chimney (the calculation must be carried out in such a way that for one heater there is a separate channel and chimney). Although in some cases it is allowed to connect several furnaces located on the same floor to one channel.
Main design parameters
If two or more pipes are used to equip the channel, it is necessary to provide cuts 0.12 mm thick at a distance of at least a meter from the pipe junction.
Also, the calculation should include the installation of valves in the channels. Moreover, the valve should have one hole, the diameter of which is 15 millimeters in the case of using peat or coal as fuel.
The chimney must be designed strictly vertically, without ledges and bends.
If refractory bricks with a wall thickness of more than 120.00 mm or heat-resistant concrete with a thickness of more than 60 mm are used to make the channel, pockets 250.00 mm deep with holes for revision (cleaning) must be provided.
The pipe must be installed strictly vertically, but deviations from the vertical by 30 degrees are allowed, with a slope not exceeding one meter.
In the event that the chimney is operated in a building with a roof made of combustible materials, spark arresters made of metal mesh are installed, the dimensions of the holes should not exceed 5x5 millimeters.
If the furnace has adjoining structures made of combustible materials, then they must be protected by cuttings made of non-combustible materials that prevent ignition.
The distance between parts of the heating system and combustible materials may vary. It all depends on the fuel used, the materials from which the chimney is made, and a number of other characteristics.
Main parameters of combustion products removal systems
The calculation of the main parameters that affect the operation of furnaces is to determine such parameters as the cross section and height of the chimney.
The diameter (section) that the chimney must have depends on the heat output that the stove has.
The dimensions are as follows:
- power up to 3.50 kW - 140 × 140 millimeters;
- power from 3.50 to 5.20 kW - 140 × 200 millimeters;
- power from 5.20 to 7.20 kW - 140 × 270 millimeters.
If the furnace has a circular cross-section of the channel for the removal of combustion products, then the calculation is made taking into account the fact that the cross-sectional area of the circular channel should not be less than the cross-sectional area of the rectangular channel.
The cross-sectional area of the round smoke ducts must not be less than the area of the said rectangular ducts.
The height of the chimney is calculated in such a way that the design:
- towered over the ridge by half a meter;
- was at a distance of one and a half meters from the ridge;
- was not lower than the level of a flat roof, it is better if it is one meter higher.
In the event that the furnace has a channel that exceeds the roof level by one and a half meters, additional extensions must be used. The specified height can lead to increased wind load and deformation of the structure.
As you can see, the stove can have a different design, height, chimney diameter, which necessitates the use of additional formulas for calculating in order to ensure a high degree of efficiency in the operation of stove heating equipment and increase its fire safety.
One of the most important parameters characterizing the chimney as a whole is the height of the chimney.
A properly designed chimney (i.e. a chimney that has the optimal configuration, diameter and height for the given conditions) provides the following advantages:
- Quality fuel combustion
- Ideal or close to ideal traction
- Rapid heating of the walls
- Rapid overcoming of the so-called dew point (temperature threshold at which condensation occurs)
In addition, the correct arrangement of the chimney should ensure that it is easy to maintain and thus guarantee its longevity.
Chimney Design Basics
The location of the chimney in the building
The chimney project must be developed in conjunction with the entire project heating system, which, in turn, is part of the overall design of the building.
The best way of accommodation is determined not only and not so much by your personal wishes (or the wishes of the customer), but first of all by the design features of the house itself.
Note!
When designing, it is imperative to take into account the location of the structural elements of the roof, in the first place - the rafters.
This is due to the fact that when crossing a pipe with some rafters, it is necessary to move the pipe to the side, which is quite difficult.
Where to lay the chimney?
As a rule, the chimney in the house is laid through the kitchen, corridor and utility rooms. But in the bedrooms and living rooms, chimneys should not be laid. This is due to the fact that at active work boiler or furnace in the chimney, quite a lot of noise is possible.
Chimneys
What affects the chimney
As we mentioned above, the height of the chimneys affects many aspects of the operation of the heating system. However, for us, the key points will be such as the efficiency of the boiler (if the design of the chimneys of the building was carried out with an error, it is possible to reduce the efficiency from 95 to 60%) and fuel consumption.
That is why, when starting the arrangement of the heating system, it is necessary to take into account not only the nominal height, but also the material from which it will be made, and its cross section, and configuration. Yes, and the location of the chimney should be determined by the project, taking into account which heating device is used - a boiler, stove or fireplace.
Choice of pipe height
And yet, speaking about the intricacies of arranging a chimney, one cannot get around the most important question - how high should the chimney be?
On the one hand, everything is simple: the higher the pipe, the more thrust. However, if the chimney is too high, the aerodynamic resistance to the movement of combustion products formed in the boiler or furnace will increase. The smoke moves up more slowly, gradually cools down, giving off its heat to the walls of the pipe.
As a result of a decrease in temperature, the mass of combustion products increases - and, accordingly, thrust decreases. That is why even the highest chimney is not a guarantee of sustainable draft.
You also need to consider exactly where the chimney is located. If the chimney is below the level of the roof ridge, then the draft will be inconsistent, as it will be very much influenced by the direction of the wind.
That is why SNiP 2.04.05-91 puts forward the following requirements for the height of chimneys:
- The height of the pipe, starting from the grate to the mouth of the pipe, must be at least 5 meters, and preferably - 6 meters or more
- Pipe located on a flat roof without a large parapet, must be at least 0.5 m high
- Pipe located at a distance of up to 1.5 meters from the ridge or parapet, should rise at least 0.5 m above their level
- When the chimney pipe is located at a distance of 1.5 to 3 meters from the ridge or parapet its mouth should be at the level of these elements of the roof
- If the pipe is located further than 3 meters from the ridge- its mouth can be located not lower than the line drawn from the ridge down at an angle of 10 degrees to the horizontal
Note! If a ventilation duct is located next to the pipe, its height should be equal to the height of the pipe.
However, the correct choice of pipe height is only half the battle. The pipe of the selected height must also be installed correctly.
The technique for erecting a chimney depends on the material that will be used, however, for any chimney, the following requirement will be true: if the height of the chimney above the roof level (from the foot of the chimney to its mouth) exceeds 1.2 m, it is mandatory to install stretch marks. To fix the stretch marks, a special clamp is put on the pipe itself, and the opposite ends of the stretch marks are securely fixed on the roof.
Estimated determination of the height of chimneys
So, we have come to the question that worries many novice builders - how to calculate the height of the chimney?
When calculating the height of the pipe, the following factors must be considered:
- Coefficient showing the level of dispersion of combustion products in the atmosphere
- Coefficient showing the settling rate of combustion products
- Mass of released combustion products per unit of time
- Number of pipes
An alternative to these calculations (by the way, professional heat engineers should still do them) can be the use of calculator programs to determine the height of chimneys.
There are many online and offline versions of such programs on the Internet that can produce in a few seconds and provide you with all the parameters you need to work.
As you can see, the correct determination of the height of the chimney is necessary condition optimal operation of the chimney, and of the entire heating system as a whole. Therefore, if you want your house to be warm and the chimney to work "like clockwork" - pay close attention to the recommendations given in this article.
8 September 2014 Alexei
A fireplace in modern cottages is a common occurrence. On dark winter evenings, it's nice to sit by the fireside and drink a cup of delicious coffee. An important component of the fireplace is the chimney.
The chimney is necessary for the ejection of combustion products to the outside and the establishment of traction. All pipes are made of special heat-resistant materials and are assembled according to specially established rules that ensure uninterrupted and safe operation of the entire furnace system. When installing the pipe, the height of the chimney and other special points are taken into account, which we will consider in the article.
Types of chimneys
When choosing a stove system, one should take into account the material from which the house is built: wood or brick. A wooden mansion burns faster and is less reliable in terms of fire safety compared to a brick house. When installing the pipe, it is very important to calculate correctly so that the combustion products are drawn out of the room without harm to health.
When installing the pipe, it is necessary to correctly install the draft, which ensures the safe removal of carbon monoxide. The optimum height of the pipe is at least five meters.
When installing heating appliances, the correct calculation of the chimney should be made:
- Select the appropriate material
- Calculate the height of the chimney
- Calculate the cross section of the chimney
- Calculate the diameter of the chimney
It is necessary to take into account the fuel that will be heated heating device. Depending on it, you should choose the right material for the pipe:
- Brick
- asbestos-cement
- fireclay
- Iron
- Ceramic
The operational properties of the brick channel are small. The service life is no more than seven years, and the level of safety also fails. When laying, a reliable solid brick is important, which is then covered with a layer of putty for sealing.
Asbestos-cement pipe is very cheap, but not environmentally friendly. When heated, it exudes carcinogens. The most reliable, but also expensive material for the pipe is fireclay. It meets all fire safety requirements, is reliable and practical. The service life of fireclay is quite long.
We watch video types of chimney systems:
The steel chimney is the most durable of all thanks to its modular design. You can always replace the damaged pipe section with a new one. The steel channel is plastic, and any number of elbows can be created from it. The steel structure rotates and bends in any direction. This is a universal material for fireplaces and stoves of any modification.
A chimney made of ceramic material is installed in rooms with a large space. The most popular is the chimney, combined with two moves. It looks like a pipe with two chimney channels.
Characteristics of the flue pipe
Regardless of the material and type heating device, the chimney must comply with the following standards:
- Perfect smoothness of the inner walls of the pipe
- round section
- stainless material
- Protect from fire
- Have sufficient height (at least 5 meters)
- Sufficient wall thickness
Is there a universal chimney
How to calculate a chimney for a fireplace and other heating systems? Is it possible to install such a channel that would correspond to any type of fuel, if its material is always selected exactly in accordance with the type of a particular fuel? At the moment, such a universal mechanism has not been invented. There are some systems that work pretty well with some types of fuel. However, they are far from quality.
Internal section
The calculation of the chimney section is mandatory requirement to the quality of the output system.
- Cylindrical shape. The heating of the gas heating system is uneven, because of this, the movement of smoke through the pipe is carried out in a spiral. Therefore, the optimal shape of the pipe will be cylindrical. It is she who will provide the perfect traction.
If you design a square-shaped chimney, eddies cannot form due to lack of draft, and smoke will collect in the corners. And the quality of the exhaust system and your health depend on the speed of the exhaust force.
Also, the cylindrical shape of the chimney channel is suitable for new generation boilers (stop strat).
We watch the video, the calculation of a square chimney:
The principle of operation of such heating devices is created taking into account the high-speed heating of the heating system. The faster the heating occurs, the more economically the boiler works, going into standby mode.
- Square shape. But for wood-burning heating systems, a square sectional shape will be just better. To calculate the cross section of the chimney, the type of fuel is fundamental. Wood fuel does not require a lot of traction, like gas, so the round section will simply contribute to the weathering of heat from the house.
Inner diameter
The correct calculation of the diameter of the chimney will ensure the smooth functioning of the entire heating system of the house. You can calculate the diameter of the chimney according to the enclosed manufacturer's instructions. But if you don't have one, follow these rules:
- To calculate a square-type chimney, the diameter of the blower should not exceed the diameter of the pipe.
- For a heating system with an open firebox (fireplace), the calculation of the chimney is 1:10 relative to the firebox.
Height
What should be the height of the chimney? It is impossible to determine an unambiguous chimney height for all types of heating systems. Here the following principle applies: the wider the diameter of the pipe, the faster the cooling of the combustion products of the fuel. As a result, condensate settles on the walls of the pipe, which blocks the functional smoke exhaust.
That is, an increase in diameter at a height of 5 meters does not contribute to an increase in traction. And if we increase the height of the chimney and reduce its diameter, then we will thereby increase the volume of warm air and reduce its cooling. And that means we will increase traction. That is, when calculating the chimney, this feature must be taken into account. It is the increase in height with a decrease in the volume of the pipe that will create strong traction. But how economical it is in terms of fuel costs, you decide.
If you want to calculate the chimney in favor of saving fuel, and decide to make the chimney height as high as possible with the minimum volume of pipe, the draft in the system will decrease dramatically. A decrease in draft can lead to the penetration of carbon monoxide into the room. Therefore, the calculation of the chimney cannot be brought into line with financial savings, this will lead to carbon monoxide poisoning.
The height of the chimney will depend on the design of the roof itself.
The calculation takes into account the distance between the chimneys, as well as:
- Roof thickness
- Roof pitch angle
- Distance from the vertical axis of the ridge
But when calculating the height of the chimney, the height of the umbrella covering the pipe is not taken into account.
The calculation of the height of the chimney depends on the required draft. It is she who ensures the correct operation of your heating system. The draft is formed due to the spread of temperatures and pressure in the pipe itself and the surrounding space.
Due to the pressure shift, warm air goes up and cold air goes down. Cold air tends to displace hot air. Accordingly, in cold weather, traction increases.
Formula for calculating thrust: hc = Hd x (ρv-ρg) (mm water column)
- Hc stands for chimney draft;
- Hd - pipe section from the branch pipe to the boiler;
- Pw is the air density;
- Pg is the density of the combustible substance.
1 mm. water. Art. = 0.0001kgf/cm2
Insufficient draft in the pipe can be caused by the short length of the pipe itself. This means that the height of the chimney must be increased. And yet, you need to consider a reasonable limit. In practice, the total length of the chimney should not exceed six meters. The question of how to build a chimney pipe can be solved independently.
Before installing a chimney, carefully read the rules and study the parameters of your heating system. Calculation of all parameters of the chimney is a complex engineering task. Therefore, it is better to entrust everything to a competent specialist and not risk your well-being.