Construction of houses

Chimneys: purpose and classification

You dream of your own country house, in which, sitting by the fireplace on cold winter evenings, you will enjoy the silence and the quiet howling of the wind in the chimney. You have already decided what kind of house you will build and where you will put the fireplace. The normal functioning of the fireplace requires the obligatory installation of a chimney with your own hands. In this article, we will highlight the main issues of the correct and safe arrangement of such systems, and tell you how to make a chimney yourself. If you follow all the recommendations carefully, you will succeed..

Table of contents:

The purpose of the chimney

A chimney is a vertical pipe with a round or square cross section, which serves to remove fuel combustion products from the heating unit into the atmosphere. The product is designed for natural draft, due to which air for combustion products enters the furnace and flue gas is discharged from it. The main parameters of a good chimney are: ideal draft, high-quality combustion of fuel, rapid heating of the walls and overcoming the condensation threshold.

A competently installed combustion product removal system in a modern home is able to protect the owners from unnecessary troubles. Also, its advantages are that it distributes heating air flows in the most optimal way. Incorrect arrangement of the chimney provokes unwanted smoke, the appearance of reverse draft, or even the threat of a fire in it. Impassive statistics show that heating problems have become at all times the main cause of fires in suburban dwellings..

Chimney types

The chimney is one of the main elements of the boiler room, because neither a heating boiler, nor a gas water heater, nor a fireplace can do without it. To create a vacuum in the heating unit, which ensures the combustion process, different types of chimneys are used..

Typical classifications of chimneys

According to their location, the channels that are used to remove smoke are wall, that is, located inside the main walls, root, which are isolated in the form of a free-standing riser, and external, which are located on the facade of the building. For rooms with brick walls, the first option is the most economical and convenient, since it does not need additional materials, they make a chimney with their own hands simultaneously with the walls when building a building.

According to the method of gas removal, heating devices are divided into two groups: with natural and forced draft. In the first case, the exhaust of gases occurs due to the built-in fan in the boiler, in the second – with the help of a draft that is created in the chimney. For a forced draft heating system, it is better to install a compact coaxial chimney.

The single-wall chimney is a stainless steel pipe that has a thickness of 0.6 – 1.0 millimeters. It is customary to use such pipes for location inside the house, or inside brick channels, because due to their heat transfer, the room can be additionally heated. Double-walled pipes have two layers of stainless steel, between which there is a layer of insulation – non-combustible basalt wool. Also, stainless steel is often housed in a zinc casing. Most often, double-walled pipes are used to equip chimneys outside the house or inside wooden buildings..

Chimney classification by material

The main advantages of a brick chimney are long service life and fire resistance, and the disadvantage is an uneven inner surface, which causes soot deposition. The pipe “overgrows” gradually and the draft decreases. It is customary to install brick chimneys at the stage of building a house..

Brick smoke ducts are characterized by good fire resistance, as well as resistance to condensation and external influences. It is possible to install such a chimney on the facade or inside the building. The main disadvantage of the design is the laboriousness of installation work, as well as significant weight. This is due to the metal rods that run inside the product..

Welded chimneys made of steel pipes corrode. If a certain amount of sulfur oxides is present in the emissions, then these substances combine with condensate and eventually form sulfuric acid, which destroys pipes. The installation of such chimneys is a long and very laborious process..

Corrosion-proof chimneys have all the properties of a “good chimney”: they are durable and easy to install, lighter than brick ones, do not corrode. Chimneys made of stainless steel can be installed through wooden floors. Do-it-yourself pipe modeling and chimney repair are possible on site.

Chimney characteristics

The optimal shape of the smoke exhaust duct is a cylinder, based on the fact that the more obstacles caused by angularity, the more difficult it is to pass through and the more soot will be deposited on the walls. The dimensions of the chimney are determined by the height and diameter of the structure..

The diameter is calculated taking into account the power, the width of its outlet, the nature and number of obstacles in the path of the combustion gases. The chimney height is calculated in accordance with building codes, taking into account the height of the building, the type of roof and the dimensions of adjacent buildings. It is important to comply with the design requirements for the horizontal sections of the chimney. Their length should not be more than 1 meter, because warm air moves vertically.

The figure below shows the distances that are recommended to be observed:

  • when installing a chimney on a flat roof, the pipe should protrude to a height of at least 500 millimeters;
  • when placing the pipe at a distance of less than 1.5 meters from the ridge, the height of the pipe should be at least 500 millimeters in relation to the ridge;
  • when the chimney is located at a distance of 1.5 – 3 meters from the ridge, it must not be lower than the ridge;
  • when placing the chimney at a distance of 3 meters or more from the ridge, it should not be below the line that is drawn from the ridge down to the horizon at an angle of 10º.

Connecting a fireplace insert or boiler to a chimney is often associated with problems of inconsistency in diameters. In this case, it is customary to use a reduction adapter. The area where the chimney is connected to the equipment must be treated with a special sealant. Further assembly of the chimney is carried out with expansion upstream of the condensate so that condensate does not escape to the outer wall of the pipe.

Chimney construction: basic rules

The mistakes that were made in the chimney business are fraught with serious consequences. Remember that when building a chimney with your own hands, it is important to comply with all building requirements and standards. Some consequences of illiterate design cause expensive alteration of the chimney, while others provoke poisoning by combustion products or fires.

Experts do not recommend using materials that are not intended for this purpose, for example, aluminum and asbestos. Changing the pipe diameter during useful operation without the involvement of specialists at least reduces the efficiency of the heating system. The load on the base of the chimney should not be greater than the value, which can lead to the destruction of the building.

Several installations can be combined into one chimney network only if there are confirming calculations that were made by a specialized specialist. Among the most dangerous mistakes are the following: insufficient thermal insulation of the pipe, which leads to charring of adjacent materials and their fire; use of ventilation ducts for smoke removal; unauthorized repair and modification without preliminary calculations.

Chimneys for stoves

The construction of a chimney for stoves is strictly regulated by building codes. So, it is recommended to build one stove for heating no more than 3 rooms, which are located on the same floor. In two-story houses, it is allowed to erect bunk stoves with separate fireboxes and chimneys for each floor..

The flue ducts of the oven can be located in the outer walls made of non-combustible material. In the absence of walls where a chimney can be placed, it is customary to use main and mounted chimneys to remove smoke. As a rule, a separate pipe or a separate channel is made for each furnace. Two ovens can be connected to one pipe, which are located on the same floor. When connecting two channels, it is necessary to provide for incisions that have a thickness of 0.12 meters and a height of at least 1 meter from the bottom of the pipe connection.

Chimneys are designed vertically without ledges. Deviations of the chimney from the vertical by 30 degrees are permissible, with a slope of no more than 1 meter. Sloped areas should be smooth. Chimneys on houses with roofs made of combustible material should be equipped with spark arresters made of metal mesh, in which there are holes that are no more than 5 by 5 millimeters in size.

Structures made of non-combustible or combustible material that are adjacent to stoves, ventilation ducts and chimneys should be protected from fire by cutting from non-combustible materials, and the resulting gaps between walls, partitions, ceilings and cuts are recommended to be filled with non-combustible material. The distance from concrete or brick chimneys to difficult-to-combustible and combustible elements of the roof must be at least 130 millimeters, from a ceramic pipe without insulation – 250 millimeters.

Chimneys for fireplaces

The requirements for chimneys for a fireplace echo the conditions that apply to stoves. The fuel is the same, the principle of operation of heating systems is similar. For example, fireplaces are often used for heating. But if we are not talking about large-scale heating, then you can get by with a radiator pipe, which is a special device made of plates that increase the heat transfer area.

As with other chimney designs, the smoke from fireplaces must be removed in a simple way. It is better if you build a straight vertical chimney that is more than 6 meters high. You can also make a more complex design, in which there are bends with an acute angle less than 45 °. If necessary, you need to use an elbow and install a tee that facilitates access for subsequent cleaning.

An appropriate level of thermal insulation is also important. The smoke heats up the pipe, which means that it is necessary to protect the ceilings and wall materials from fire. If a sandwich chimney passes near wood or plastic, it is customary to insulate it with basalt-based material. The flue gas outlet must also be protected from cold. For example, a single wall stainless steel pipe is not permitted outside. Protect the chimney with an installed weather vane or fungus.

Chimney for solid fuel and gas boiler

Heating boilers that operate on solid fuels are close to fireplaces and stoves, as well as to gas boilers. With the first group, they are united by wood as a common type of fuel and the frequent need to clean the apparatus from ash, with the second – by the similarity in the distribution of energy for heating. The scheme for the construction of a chimney for solid fuel boilers is broadly similar to.

The chimney for gas boilers must have a channel in its design – two devices can be connected to one channel, which are located at a distance of at least 750 millimeters. It is imperative to build a sealed chimney to prevent carbon monoxide leakage and a condensate-resistant structure. Modern high-performance gas boilers produce 1-3 thousand liters of condensate per year, and due to the low temperature of the outlet gas, the condensate cannot evaporate, but flows down the walls of the chimney, penetrating and destroying the brick.

It is impossible to worsen the chimney draft for a gas boiler. The ideal cross-section for the exhaust duct is round. An uneven or rough inner pipe surface will impair traction. The cross-section of the smoke exhaust duct must not be less than the diameter of the flue pipe on the connected appliances. For example, if the diameter of the outlet on gas boilers is 150 millimeters, then the diameter of the exhaust duct should not be less than 150 millimeters. Such a chimney should go into the sky, without the presence of covers and visors.

Chimney for saunas and baths

The firebox and chimney of a Russian bath or Finnish sauna require thermal insulation. It is customary to isolate the ceilings by analogy with the above described chimneys, and the wall material next to the firebox must be covered with metal sheets. The excess heat generated by the chimney can be used for business.

A popular option for increasing efficiency is the use of a metal mesh, where stones are poured, which are capable of enveloping a hot chimney and heating up. Another addition is the combustion intensity regulator. The chimney draft should maintain combustion at the required level, not letting out all the heat into the street and creating a temperature in the room close to 70-80 degrees Celsius. It is clear that there can be no question of smoke entering the steam room..

Thus, you got acquainted with the intricacies of the device of a functional and technically correct chimney and watched the video of installing the chimney with your own hands. Each option has its own subtleties of installation and needs to be consulted with a specialist. Follow the basic intricacies of installing a smoke exhaust duct, and the heating system in your home will work with high efficiency..