Heating a house with gas requires strict adherence to standards for the installation of equipment. The chimney for a gas boiler is an integral part of the heating system. Not only the high-quality work of heating depends on the correctness of its installation, but also the safety of the residents. You should understand the requirements and recommendations for the installation of gas equipment.
Why do you need a chimney for gas boilers
During combustion, a substance hazardous to human health is formed. The consequence of inhaling carbon dioxide can be a sharp deterioration in general condition and even death. If the chimney for the boiler is installed incorrectly or is damaged, the chances of getting poisoned increase.
Carbon monoxide is insidious in that it does not have a pronounced odor and color, so poisoning occurs gradually. Carbon monoxide provokes oxygen starvation and negatively affects all biochemical processes in the body. In order to prevent tragedy, the installation of the chimney should be taken very carefully.
Materials for making
The chimney pipe can be made of different materials, but all of them must meet certain requirements - to be airtight, fire-resistant and resistant to aggressive chemical environments.
Brick
Installing a chimney pipe made of brick is not a new and even outdated method. It is not very popular, primarily because of the massive structure, under which it is necessary to mount a separate foundation. This process requires a lot of effort, time and financial costs. In addition, only an experienced master can perform the masonry with high quality.
There are also technical drawbacks to this design. Unsmooth inner walls provoke accumulation of soot, which subsequently leads to a decrease in thrust. Another disadvantage is the hygroscopicity of the brick. Condensation formed on its surface is absorbed by the brick and causes its rapid destruction.
To solve these problems, an asbestos or steel liner is mounted inside the brick pipe. In doing so, it is necessary to take into account the following:
- The liner at the joints must be sealed. When installing an asbestos-cement pipe, putting cement mortar on the joints will not solve the issue of absorbing condensate. In this case, you will need to use hydrophobic chemically resistant compounds or make the connection using sealed clamps.
- Insulating the pipe will reduce the formation of condensation. The thermal insulation material must have moisture resistant properties.
- To collect condensate and remove it from the bottom to the pipe, a container is mounted in an accessible place.
A brick chimney, mounted taking into account the above rules, will not cause difficulties even with abundant condensation.
Stainless steel
Food grade stainless steel is a material with unique performance properties. It can withstand prolonged exposure to harsh chemicals. It differs from other varieties in a higher price, but its service life is also higher.
The uniform temperature of the pipe contributes to the formation of small amounts of condensate and its rapid evaporation - it is important that it does not cool down. For this, it is insulated. An effective design for a chimney is provided by a "sandwich" type material with a heater inside in the form of non-combustible basalt wool. However, it is recommended to insulate the area located outside, so as not to lose traction and extend the life of the chimney.
The advantage of the sandwich lies in the lower consumption of insulation compared to the arrangement of a single-wall stainless steel structure. In this case, the outer material of the sandwich can be made of cheaper galvanized steel, which is not exposed to contact with condensate, high temperatures and has additional external insulation.
Primary requirements
Requirements for smoke channels are reflected in regulatory documents and must be observed. Among them, the following can be noted:
- the joints must be sealed and moisture resistant;
- the lower part of the pipe must be equipped with a plastic or steel condensate trap;
- the height of the pipe must provide good traction, therefore, it must rise at least 50 cm from the roof surface;
- a visor is mounted above the pipe, which will protect it from precipitation and debris.
The listed rules will guarantee the safe operation of the gas heating system.
Chimney device and diagram
The combustion chamber is of two types - open and internal combustion. This factor determines the type of chimney. In the first case, an ordinary pipe is mounted, and in the second, a coaxial one.
The principle of operation of an open combustion chamber is that the flue gas is discharged through a pipe into the atmosphere due to the draft, and oxygen for combustion enters the chamber from the room in which the boiler is installed.
For a boiler with a closed chamber, a coaxial chimney is installed. It consists of two pipes inserted into one another. One is used to supply air to support the combustion process, and the other is used to remove combustion products. On the street, such a pipe is often taken out through the wall, since the turbine provides traction.
Correct installation
Section selection
The chimney cannot have an inner diameter smaller than that of the outlet on the boiler, through which the equipment and the pipe are connected. It is also worth considering that the curvature and narrowing of individual sections of the chimney are unacceptable throughout its entire length.
If two boilers are to be connected to one pipe, its cross section is increased. The size of the inner diameter of the pipe must be equal to the sum of the diameters of both nozzles.
Drafts and padding
The location of the pipe must be vertical. When designing a chimney, it is best to avoid sloping areas. If this cannot be achieved, it is important to take into account that the slope from the vertical location should not exceed 30 °, and the section should remain within the standard values. The length of the section mounted with a slope should not exceed the height of the room.
There is a limited number of permitted turning sections - there should be three of them.
Connection requirements
A tight connection during the installation of individual parts of the chimney is obtained through the use of special clamps. When installing pipes, take into account the material of adjacent surfaces.If they are made even from raw materials that are hardly combustible, the distance to the chimney should be 25 cm or more. At the same time, it is recommended to insulate the pipe from the outside with asbestos cardboard or other fire-resistant material. If the material is fire resistant, the distance can be shortened to 5-10 cm.
Special attention should be paid to the joints of the chimney duct and fasteners - they use durable material that is resistant to mechanical stress. It is important to avoid stress on sloped areas.
When assembling a stainless steel pipe, the immersion depth of one element in another should be equal to the radius of the channel or slightly more. In this case, the formation of gaps is unacceptable. Otherwise, there will be a possibility of carbon monoxide entering the room.
Roof pipe location
When choosing the location of the flue, take into account that for a gas boiler, the location of the channel above the roof at its highest point should be at least 50 cm.The distance from the chimney to the edge of the overhang should not exceed 150 cm.
If the protruding part of the chimney is at a distance of more than three meters from the ridge, its height may be less than 50 cm.
If the roof is flat, the chimney should be 1 meter high. If the roof structure is combined, the smoke channel should rise 2 meters above its surface.
The inside and outside of the pipe is insulated to prevent the formation of too much condensation. It will still appear, but inside the insulated pipe it will evaporate. If you allow an excess of condensate inside the channel, over time, corrosion processes will begin to appear, which will lead to the destruction of the entire structure. Lack of insulation also reduces traction.
Possible mistakes when choosing a gas duct
If during the operation of the heating system an excessive amount of condensate forms or there is not enough draft, most likely, the installation of the chimney was performed incorrectly. The most common mistakes when installing a flue gas duct include:
- wrong choice of channel section and height;
- insufficient use of insulation on the outside of the pipe or in the area inside an unheated attic space;
- violation of fire safety requirements.
The reason for improper operation and rapid destruction of the flue gas pipe can be the choice of an unsuitable material for it. For example, it may be unstable to high temperatures, corrosive chemicals, or insufficient wall thickness.
