Gas boilers are a very popular solution in places where there is access to a centralized gas supply. To ensure reliable and efficient heating of a house with a gas boiler, it is necessary to choose the right material for the chimney and carry out its installation in accordance with accepted standards. In this case, mistakes must not be made, since they will lead to a deterioration in draft, therefore, combustion products will not be completely removed, which will negatively affect the efficiency of the boiler. Gas consumption will increase, so heating costs will increase. In addition, improper operation of the chimney can pose a threat to human life, since combustion products, instead of being discharged outside, can enter the room. Redesigning a chimney is not only expensive, but also time-consuming, so before installing it, you need to familiarize yourself with how to do it correctly, and take into account the advice and recommendations of specialists.
One of the most popular types of fuel is gas, therefore gas boilers are a common and demanded equipment. During gas combustion, the temperature of the products discharged through the chimney does not exceed 150-180 degrees. This fact largely determines the requirements for the materials used to create the chimney.
When building a new house, the type of heating equipment is foreseen in advance, and its project is also being developed. If it is necessary to install a gas boiler in an old building, its reconstruction may be necessary.
To create a chimney for a gas boiler, different materials can be used, but all of its types, except for brick, have the following elements in their composition:
A chimney inside a building usually has more fittings than an outside chimney
As part of the heating system of a house, the chimney is of great importance, since it serves to remove fuel combustion products. Not only the efficiency of the gas boiler operation, but also the safety of residents depends on how correctly it is executed and installed.
To correctly make a chimney, you need to familiarize yourself with the existing requirements for this element of the heating system. One or two boilers can be connected to one chimney, provided that the exhaust of combustion products is carried out into openings located at different levels at a distance of more than 50 cm from one another. Elbows can be at the same level, but cutting devices installed at a height of 50 cm or more must be used.
When installing two boilers located at different levels, the flue gas outlets must be at least 50 cm apart.
Of particular importance is the correct calculation of the chimney cross-section, while it cannot be less than the size of the boiler outlet. When several heating devices are connected to one chimney, its diameter is determined taking into account the simultaneous operation of all boilers.
Gas boilers have high efficiency, usually it reaches or even exceeds 95%, so the temperature of the combustion products will be low. But it must be borne in mind that this produces a large amount of condensate, which has a particularly negative effect on the brick chimney. To reduce the destructive effect of condensate on a brick, experts recommend casing such chimneys using a special pipe made of stainless steel, or lining with a corrugated pipe.
For a gas boiler, the optimal chimney section is a circle, its oval shape is allowed, and a rectangular configuration is rarely used, since it cannot provide high draft.
The following requirements are put forward for the chimneys of gas boilers:
There should be no more than three turns in the chimney of a gas boiler
The installation height of the chimney head above the roof depends on its distance to the ridge
It is strictly forbidden:
|Installation location of the bend||The smallest distances, m|
|to the natural draft boiler||to the boiler with a fan|
|Equipment power||Equipment power|
|up to 7.5 kW||7.5-30 kW||up to 12 kW||12-30 kW|
|Under the ventilation hole||2,5||2,5||2,5||2,5|
|Near the ventilation hole||0,6||1,5||0,3||0,6|
|Next to the window||0,25||0,5||0,25||0,5|
|Above a window or vent||0,25||0,25||0,25||0,25|
|Above ground level||0,5||2,2||2,2||2,2|
|Under parts of the building that protrude more than 0.4 m||2,0||3,0||1,5||3,0|
|Under parts of the building protruding less than 0.4 m||0,3||1,5||0,3||0,3|
|Under another bend||2,5||2,5||2,5||2,5|
|Next to another bend||1,5||1,5||1,5||1,5|
You can choose different materials for creating a chimney, but they must:
For the correct choice of material for the chimney, you need to familiarize yourself with the pros and cons of each option.
Until recently, brick was most often used to create a chimney for a gas boiler, but now other materials are usually used. This is due to the fact that the brick has a lot of weight, so a strong foundation must be erected to create it. You will not be able to make such a chimney on your own; you will have to invite a master.
Among the main disadvantages of a brick chimney, the following should be noted:
To eliminate the disadvantages of a brick chimney, it is enough to insert a pipe of the required diameter inside. It can be metal or asbestos, as well as corrugated pipe.
For the reconstruction of an old brick chimney, a stainless steel pipe is placed inside
When creating a combined chimney, you must adhere to the following rules:
If you carry out such a reconstruction of a brick chimney, then it will reliably, efficiently and safely serve for many years.
Due to the fact that the temperature of combustion products in modern gas boilers is low, condensate is constantly and in large quantities formed in them. If there is good draft in the chimney, then the bulk of the condensate goes out with the smoke to the street, and if it is well insulated, the rest evaporates. If everything is done correctly, then although condensation is constantly formed, there will be a minimum amount of it in the condensate trap.
In order for pipes made of stainless steel to serve for a long time, they must withstand prolonged exposure to aggressive substances. Food grade stainless steel does this best, but is expensive.
Sandwich pipes are the best option for creating a chimney
To reduce the likelihood of condensation formation, the chimney pipe must not be allowed to cool, therefore it must be insulated. If a sandwich pipe is used for laying an external chimney, then to extend its service life it is better to perform additional insulation. To do this, you will need to lay only one layer of insulation, while when using a single-wall structure, at least 2-3 layers will be required. Although the cost of a single-wall pipe is lower than that of a sandwich structure, due to the need to use several layers of insulation, in the end result, their cost is practically equal. When creating a chimney for a gas boiler, it is best to use a sandwich pipe.
When using single-wall pipes, the part that is outside the residential part of the building must be well insulated
Installation of pipes when creating a chimney outside the building is carried out "by condensate", which means that the upper pipe is inserted into the lower one. If the chimney is laid inside the building, then it is done "through the smoke" - the upper pipe is put on the lower one, which prevents gases from entering the room.
Depending on whether the chimney is inside or outside the house, the assembly is carried out "by condensate" or "by smoke"
The reliability of a sandwich pipe will be higher than that of a single-walled pipe due to the presence of two layers of metal. If you decide to insulate a sandwich pipe, then you can take one with an outer pipe made of galvanized metal. It is cheaper than made of stainless steel, has no contact with condensate and is not visible under the insulation, so this solution will save money.
The main advantages of a ceramic chimney are its high reliability and durability - the service life is 30 years or more. Ceramics are highly resistant to the action of the acid contained in the condensate that settles on the pipe walls. Such a chimney can be used with a boiler operating on any type of fuel, it provides good draft, heats up quickly and accumulates heat.
But it also has several drawbacks:
Ceramic chimney resists aggressive substances well, but is heavy
In the past, asbestos pipes were often used to create the chimney of a gas boiler. This is due to the fact that the temperature of the combustion products is low, so this design can withstand it. The main advantage of asbestos pipes is their low cost. Among the shortcomings, it is worth noting the rough surface and the difficulty of sealing the joints. Do not use an asbestos pipe if the temperature of the combustion products is more than 250-300 degrees, as this can lead to damage to the pipe. It is imperative to study the boiler documentation to determine whether the selected material is suitable for creating a chimney.
When creating a chimney from asbestos-cement pipes, you must adhere to the following rules:
Considering the fact that when using asbestos pipes you need to suffer with sealing joints, it is much easier to use stainless steel pipes to create a chimney, the installation of which is faster, and the price does not differ much.
Such stains occur due to poor sealing of asbestos-cement or metal chimney pipes.
In this case, one pipe is placed inside the other, and they are connected to each other by thin bridges. You purchase a ready-made chimney, so its installation is quick and easy.
This solution allows you to remove combustion products from gas boilers in the absence of the possibility to install another type of chimney. Most often these are apartment buildings or structures in which there are no chimneys. Such a chimney can only be used with a boiler with a closed combustion chamber.
The main advantage of a coaxial chimney is that it simultaneously performs two functions: removing flue gases and supplying air to the combustion chamber.
The coaxial chimney is used with gas boilers with a closed combustion chamber
Installation of this type of chimney provides the following advantages:
For a boiler with an open burner, a flat vertical chimney is required, which can be built in two ways.
For a gas boiler with an atmospheric burner, you can make an internal or external chimney
When creating chimneys, both options are used, but making the outside is easier. In the case of an internal arrangement, it is difficult to create a passage through the floor and the roofing pie. To ensure fire safety in these places, special pass-through elements are used.
To calculate the diameter of the chimney, it must be borne in mind that this value is in direct proportion to the power of the heating device. The condition must be taken into account: the cross-section of the inner diameter must be constant along the entire length of the pipe.
When performing calculations, experts recommend that for each kilowatt of gas boiler power, there should be at least 5.5 cm2 chimney area. This is the optimum value, which ensures good draft, efficiency and safety of the gas boiler.
When installing a chimney from a sandwich pipe, only its inner diameter is taken into account
If we talk about such a parameter as the height of the chimney, then for a gas boiler it should be at least 5 m. The specific requirements for the location of the pipe head have already been discussed by us in the section "Features of the chimney arrangement for a gas boiler".
The calculation of the chimney diameter can be done in two ways.
When calculating the diameter of the chimney, it is necessary to take into account the passport, and not the thermal power of the boiler. For example, with a rated power of 1.5 kW, the thermal power can reach 38 kW, but a lower value is taken for the calculation.
Let's consider a specific example: let's say the boiler power is 24 kW.
|Chimney diameter, mm||100||125||140||150||175||200||250||300||350|
|Gas boiler power, kW||3,6–9,8||9,4–15,3||7,1–19,2||13,5–22,1||18,7–30,4||24,1–39,3||37,7–61,3||54,3–88,3||73,9–120,2|
For a gas boiler, you can make a chimney inside or outside the building. In each case, the owner independently decides how to mount the smoke channel, but to make it easier to decide, you can be guided by the data from the table.
|Internal installation of the chimney||External installation of the chimney|
|The chimney, passing through all the rooms, heats them additionally, so only that part of it that is outside the living quarters needs to be insulated.||It is necessary to carry out thermal insulation of the chimney along its entire length.|
|Since a large section of the pipe runs inside the building, there is a high probability of carbon monoxide entering it, and the fire hazard also increases.||High level of safety, since even if carbon monoxide leaks, it will remain outside.|
|Since additional elements are used, the installation of the system becomes more complicated and its cost increases.||Fewer chimney elements, so installation is easier and faster.|
|If it is necessary to carry out repair work, additional difficulties arise.||Since the chimney is located outside the building, there is always free access to it, so repairs are simple and quick.|
Comparing the data obtained, everyone will be able to decide for themselves in which way it is better to mount the chimney in his case.
The process of creating an internal chimney consists of the following steps.
It is necessary to make a passage for the pipe in the ceiling of the house, as well as in the roofing pie
The pipe and condensate trap are connected to the boiler using a tee
Usually the length of one vertical pipe is not enough to create a chimney, so it is increased
The box for the passage through the ceiling can be purchased ready-made or made yourself from stainless steel
If the height of the attic is large, then the pipe is additionally attached to the elements of the rafter system
To design the passage of the chimney through the roofing pie, a special passage element is used
To protect the chimney from atmospheric precipitation, a cone-shaped tip is used
Basalt wool is used for thermal insulation of the chimney passage through the ceiling.
The procedure for installing the chimney outside the building will be slightly different.
A special passage element is used to lead the chimney through the outer wall.
To bring the chimney to the street, a hole is made in the wall
After installation in the pipe hole, it is sealed with high quality
A tee and a revision are attached to the element protruding from the wall
To strengthen the joints, clamps are additionally used
In order to avoid mistakes when independently installing a chimney for a gas boiler, the following facts must be taken into account.
Condensate must not be drained outside from the condensing boiler, as it will freeze in winter and the boiler will stop working.
To collect and drain condensate, if its spontaneous drainage is impossible, a special condensate trap is used
All work on the installation of the chimney, both inside and outside the building, must be performed carefully in order to obtain a sealed structure. The correct installation of the chimney will determine not only the quality of the heater, but also the safety of all residents of the house.
Any heating device, and especially one that runs on gas, is a source of increased danger. All work related to the installation of a gas boiler, as well as the creation of a chimney, must be performed correctly and in accordance with existing standards. Before starting the installation of the chimney, all calculations must be performed correctly. If you are not confident in your abilities, then it is better to entrust the work on installing a chimney for a gas boiler to specialists.
Imperceptibly during the holidays, winter approached its middle. The traditional dacha planting chores will begin very soon. But while it is cold outside and February frosts are still expected ahead. Comfort and coziness in a home is associated with warmth. And whether it is enough in a country house directly depends on the heating equipment and its correct installation.
One of the important elements of a solid fuel boiler is a chimney. Compliance with all the rules for its installation is a guarantee of not only stable efficient operation of the equipment, but also the fire safety of the building. Therefore, in continuation of the topic of installing solid fuel equipment, which dealt with the device of the boiler room, we will consider how to correctly make a chimney for a solid fuel boiler.
Installation of chimneys for a gas boiler is carried out in the direction of the structure from the bottom up, that is, from the heating objects of the room towards the chimney. With this installation, the inner tube is pushed onto the previous one, and the outer tube is inserted onto the previous one.
All pipes are fastened to each other with clamps, and along the entire laying line, every 1.5–2 meters, brackets are installed to fix the pipe to a wall or other structural element. The clamp is a special fastening element, with the help of which not only the parts are connected to each other, but also the tightness of the joints is ensured.
The laid sections of the structure in a horizontal direction up to 1 meter should not come into contact with elements that pass near communications. The working channels of the chimney are located along the walls of the buildings.
Be sure to install a bracket on the wall every 2 meters of the chimney, and the tee is attached using a support bracket. If it is necessary to fix the channel to a wooden wall, then the pipe is lined with a non-combustible material, for example, asbestos.
When mounted on a concrete or brick wall, special aprons are used. Then we bring the end of the horizontal pipe through the wall and there we mount the tee required for the vertical pipe. It is necessary to install the brackets on the wall every 2.5 m.
The next step is to attach, raise the vertical pipe and lead it out through the roof. The pipe is usually assembled on the ground and the fastening for the brackets is prepared. The fully assembled volumetric tube is difficult to fit on the elbow.
For simplicity, a hinge is used, which is made when welding pieces of sheet metal or cutting a pin. Typically, the vertical pipe is pushed into the tee pipe and secured with a pipe clamp. Attaching the hinge to the knee is similar.
After lifting the pipe in a vertical position, the pipe joints should be bolted where possible. Then you should unscrew the nuts of the bolts to which the hinge was fastened. Then we cut or knock out the bolts themselves.
With the hinge selected, attach the remaining bolts to the joint. After that, we tighten the remaining brackets. We first adjust the tension manually, then we fix the cable and adjust it with screws.
Necessary distances to be observed when placing the chimney outside
The installation is completed by checking the chimney draft. To do this, bring a burning piece of paper to the fireplace or stove. Draft is present in case of deflection of the flame towards the chimney.
The figure below shows the distances that must be observed in various options for the location of the chimney outside:
The setting depends on the type of channel directions required for the combustion of the fuel. In the interior of the room, there are several types of chimney directions:
Chimney support bracket
It is necessary to install support brackets for fixing the tees every 2 meters of the flue duct, it is necessary to provide additional fastening to the wall. Under no circumstances should horizontal sections be created above 1 meter when installing the chimney.
When installing chimneys, consider:
The gas boiler flue connection is carried out on the basis of building codes and the manufacturer's instructions. The chimney must be cleaned up to four times a year (see How to clean the chimney).
To optimally calculate the height of the chimney, it is necessary to take into account the type of roof and the height of the building:
The main advantage of installing such a pipe is that the air in the room does not dry out, therefore, there is no need for frequent ventilation or the purchase of expensive climate systems. The air stream from the street, passing through the system, gradually heats up, improving the combustion process. Thanks to this, the gas burns out completely, and this increases the efficiency of the equipment.
You should know this! You can choose a pipe for any heating equipment. Manufacturers produce designs of different diameters and materials. In addition, the installation of a coaxial chimney of a gas boiler is easy to do with your own hands, and this is a significant budget saving.
Flow circulation principle
The standard single-circuit gas boiler is intended for heating only. Its design allows water to be heated in a loop heating system. To heat water in such cases, gas water heaters or boilers are used. But this is unprofitable if a double-circuit gas boiler can be used. There is much more effect from such a device. In addition to the fact that you do not need to buy and connect additional equipment, it allows you to almost simultaneously heat water for use in the bathroom, shower, etc.
Gas boilers differ in the type of heating
Remember! Single-circuit gas boilers are used only for heating, double-circuit ones - for heating and heating water in unlimited quantities.
Electronic piezo-ignition devices are installed to ignite the boiler. Also, the combustion process is controlled by automation, which excludes the possibility of supplying gas to the combustion chamber in the absence of traction in it or in an extinguished state. Residues of combustion products are discharged due to natural exhaust or turbo compulsion.
Modern gas boilers are completely environmentally friendly
Let's talk about the best option for a heat generator for the heating system of a house - a condensing gas boiler.
To organize the heating system of a country house in the modern world, many different equipment are used. It can run on gas, electricity or wood. For those who are especially concerned about environmental safety, a condensing boiler is the best choice. Thanks to its high efficiency of 98%, it will also help to significantly save on fuel. Heating equipment manufacturers provide a wide selection of these units. You shouldn't worry about their high quality either, because the devices are manufactured using innovative technologies, reliable and durable materials.
The condensing gas boiler originated from the simplest gas-fired convection unit, with the most elementary operating principle. Natural or liquefied gas acts as a fuel for it. At the moment of its combustion, water and carbon dioxide are formed, releasing energy in large quantities. The heat carrier is heated by the released heat and circulates through the heating system of the dwelling. With this principle of operation, the efficiency is about 90%, the remaining 10 simply fly out into the street through the chimney. The condensing gas appliance developed by the engineers solved this problem.
In the unit, after burning fuel and transferring most of the heat to the heat exchanger, the condenser cools the gaseous combustion products to 50-60 ° C, thereby helping the development of water accumulation. Due to this, the efficiency increases, and, therefore, the volume of heat transferred to the coolant increases. Additional energy is also obtained due to the condensation of water vapor, which in conventional devices is lost when the vapor-gas mixture evaporates. The device takes the heat generated during this procedure and transfers it to the coolant. Thus, the efficiency of the device approaches 100%, because he can get almost everything possible from the combustion process. Moreover, such a high efficiency is achieved while reducing the consumed energy resources.
The design of a condensing boiler, although not essential, differs from a simple gas appliance. Its most important elements are as follows:
In the primary heat exchanger, which is connected to the combustion chamber, the emitted gases are cooled to a temperature above the dew point. After that, the flue mixture goes to the condensing heat exchanger, where it is further cooled to less than 56 ° C. Steam accumulates on the walls of the heat exchanger, giving off the last heat. Condensate is collected in a tank, from which it is discharged through a pipe into the sewer. The heat carrier water moves in the opposite direction to the steam-gas mixture. When cold, it first heats up in a condensing heat exchanger, and then goes to the primary heat exchanger, where it heats up to the temperature desired by the consumer.
The boilers themselves are made of stainless steel and silumin, the heat exchanger is cast, because the condensate is a mixture of diluted inorganic acids. Such materials allow to extend the life of the device, and the absence of seams - to prevent corrosion. To avoid the destruction of the chimney by a small amount of condensate falling on it, it is made of plastic or acid-resistant stainless steel.
The burner helps to regulate the supply of heat at different times throughout the day. It can be simulated (allows you to gradually change the power during operation) or non-simulated (with a set value), while the burner switching frequency adjusts the device to the required parameters. In the best condensing gas boilers, simulated burners are often installed.
This heating equipment is divided into:
Before buying equipment, you should decide on its purpose, the area of the premises that it should heat. If there is no need for hot water, then for a small cottage it will be advisable to take a wall-mounted single-circuit condensing boiler.
The growing popularity is due to a number of advantages of condensing boilers:
The disadvantages of condensing boilers can be distinguished much less, but nevertheless, this almost ideal unit has them:
The device is an innovation of the heating system, characterized by quality, environmental friendliness and high efficiency. Despite the high cost, it is safe to say that it is still worth buying a condensing boiler, because such an investment will certainly pay off, allowing you to save on heat carriers with maximum heat transfer.
If you have any questions on this topic, ask the specialists and readers of our project here.
If you have a fireplace (fireplace stove) with a closed firebox, the chimney should be cleaned at least once a year, before the start of the heating season. A long-burning stove with a constant firebox contaminates the pipe much faster: the layers of soot, which are terrible for their combustion, grow in just a couple of months. But gas and liquid fuel equipment gives its owners much less trouble: even with intensive operation, you will have to do chimney prophylaxis every 2 to 3 years. It is best to use a weighted metal brush for cleaning. In winter, when it is difficult to climb onto the roof, you can periodically add special preparations to the firebox, partially destroying creosote deposits.
|Comparative characteristics of "exhaust" of heating units with a thermal power of 10-12 kW||Mass fraction of suspended solids in smoke,%||Condensation *, l / day|
|Flue gas unit type, С||Temperature|
|Fireplace with closed hearth||Up to 400-600||40-50||0.5-1|
|Fireplace stove with flue||Up to 250-450||40-50||0.5-1.5|
|Long burning oven||150-600||Up to 70||To 10|
|A gas boiler||140-250||10-20||0.2-0.4|
|Low temperature boiler (gas, liquid fuel)||Up to 120||5-7||Up to 15|
|* When using a sandwich-type steel chimney with a length of 6 m, insulated with a 30 mm thick layer of mineral wool.|
Author: Well-known construction journalist V. Grigoriev. Drawing: M. Chernov. Photo: StroyExpertiza Plus
Frozen condensate at the outlet of the coaxial chimney.
Options for the location of a coaxial chimney in a private house and the minimum distance between the axis of the pipe and the nearest objects, m.
Each chimney system must be supplied with detailed assembly and installation instructions. Before starting the installation, you need to compare the requirements set forth in the instructions with the requirements of the currently valid regulatory documents, and be guided by the more stringent ones.
Variants of arrangement of coaxial chimneys with vertical outlet.
The coaxial chimney and closed combustion chamber of a gas boiler eliminate the influence of the combustion process on the atmosphere inside the room, thereby increasing the comfort of people living in the house. Thanks to their positive qualities, chimneys "pipe in pipe" every year acquire more and more adherents among those who plan to equip a house with an efficient and economical gas heating system.
Interior solution: decorative grilles for heating radiators
Optimum thermal insulation for heating pipes
Self-insulation of heating pipes on the street