Coaxial chimney for gas boiler is a new technical solution that replaced standard options. It is used for heat generators with closed camera boiler combustion). Main feature and the great advantage of this chimney is that the combustion air into the boiler firebox comes not from the house, but from the street.
Purpose
Coaxial is designed to perform 2 functions at once:
- removal of combustion products outside;
- ensuring the flow of fresh air necessary to maintain the gas combustion process in the chamber.
Boilers with a closed combustion chamber are usually equipped with a chimney, the length of which is usually no more than 2 m. It should be noted that most often the chimney is installed outside through a wall. A less common option is when it is brought out through the ceiling and roof.
If the place in the wall where the chimney is supposed to be brought out is located near a window, then it is best to place it just above the roof. However, in this case it is necessary to install the vertical part of the chimney.
Coaxial chimneys installed in vertical and horizontal positions. They differ only in the installation method, but their operating principle is the same.
Components
A coaxial chimney for a gas boiler consists of the following components:
- several straight pipes;
- tees;
- cleaning;
- condensate collector;
- upper tip of the chimney;
- knee (angle 90).
A chimney is formed from straight pipes. The purpose of the elbow is to connect a horizontal chimney with its vertical part, as well as a gas boiler.
If the chimney is located only in a horizontal position, its kit includes the following elements:
- straight pipes;
- knee (angle 90);
- chimney tip (side).
Coaxial chimney for a gas boiler, like everyone else engineering systems, has its pros and cons.
Advantages of a coaxial chimney: customer reviews
- Oxygen to support the combustion process comes from outside, and not from the room. This is the main advantage of a coaxial chimney. Its design includes two pipes, one of which serves as the outer shell and the other as the inner shell. Through a pipe with a smaller diameter, combustion products - exhaust gases - are removed, and air is supplied to the combustion chamber of the boiler through the outer pipe to support combustion.
- The design takes up quite a small amount of space, which allows you to significantly save space indoors.
- The chimney heats the incoming outside air with exhaust gases, which significantly increases the efficiency of the boiler.
- The system is fireproof. When exhausted, flue gases are cooled by air entering the combustion chamber of the heating unit, which reduces the risk of a possible fire. There is no need to additionally insulate the chimney using highly flammable materials.
- Easy to install.
A similar chimney system can be installed on following types boilers:
- on gas;
- solid fuel;
- on liquid fuel.
Disadvantages of coaxial chimneys
Freezing. According to user reviews, this is the most important and serious drawback installed chimney. Its first models that appeared on the markets were not designed for low temperatures operation (-15 - -30 °C), which can cause freezing of the structure and failure of the heating unit. The coaxial chimney for a gas boiler (photo presented in the article) was intended for countries with a milder climate.
But not all experts are so categorical. In their opinion, the main reason for the freezing of such a chimney is incorrect thermal engineering calculations. If the chimney is selected correctly, it will not freeze.
When installing a vertical coaxial chimney, there is a problem of condensate collection. Since this drawback is known to manufacturers, then certain models are equipped with a condensate collector.
Carrying out installation work
When installing a coaxial chimney yourself, be sure to read the included manufacturer’s instructions and follow all recommendations:
- During installation, only those materials and components that have been tested by the state gas inspection should be used; It is strictly prohibited to make any changes to the design and configuration of the chimney.
- When carrying out work, using materials that do not belong to the chimney manufacturer is strictly prohibited. All necessary additional components should be purchased only from a special service center.
- All parts of the chimney are connected and tested for leaks flue gases.
- The use of sealants and adhesives is prohibited.
- It is prohibited to join pipes within the thickness of a wall. The junction should be provided outside it.
- The installation of a horizontal coaxial chimney is carried out (unless there are other instructions from the boiler manufacturer): for condensing units 2-3° towards it, for classic version 2-3° from it, to remove condensate and prevent precipitation from entering the boiler.
- The length of this chimney depends on the model heating boiler, complexity of the chimney line.
- It is prohibited to install chimney outlet equipment below ground level into the window pit of a semi-basement building.
- It is important to remember that during the operation of the chimney, all responsibility for breakdowns and possible breakdowns rests with the installer.
Installation sequence
The chimney is attached to the boiler and ducted outside the room. It is best to remove all unnecessary and flammable items before work.
Installation of a coaxial chimney for a gas boiler begins with choosing a location for the heating unit and chimney. It is better to install a gas boiler together. The most optimal option is when the chimney is located 1-1.5 m above the boiler. If necessary, the chimney can be lengthened, but taking into account that there are no more than 2 bends, and their total height does not exceed 3 m.
Now you can start drilling holes required diameter(within 11 - 12.5 cm).
The next stage of work is assembling the chimney of the required configuration. Clamps are used for all connections. The chimney that exits the room must have a slight slope to remove moisture (condensation).
That's it. All that remains is to put on decorative overlays for aesthetics.
How to make a choice?
When choosing, first of all, you should pay attention to the recommendations provided by the boiler manufacturer. In some cases service centers They do not accept the equipment for warranty due to the installation of a coaxial chimney that is not recommended for this boiler.
The functions of a coaxial chimney include ensuring not only the removal of flue gases, but also the intake of oxygen from the outside; for this reason, the reliability of its operation is very important. We suggest considering proven foreign brands: Baxi, Vaillant, Viessmann, Navien.
Coaxial chimney Baxi
It is made of high-strength polymer material. The standard kit includes a chimney pipe 1 m long, a 90° elbow, a wind protection nozzle, and decorative rings. If necessary, you can purchase an extension cord. It should be taken into account that a coaxial chimney for a Baxi gas boiler, the length of which is up to 1 m, requires the installation of a narrowing diaphragm on the boiler air duct. This is necessary to compensate for draft, since the boiler fan power is designed for a certain length of the chimney (5 m). If there is no diaphragm, an excess amount of air will enter the combustion chamber, which will reduce the efficiency of the boiler. To avoid freezing, the coaxial pipe is installed so that its protrusion from the wall is no more than the length of the tip. When exceeds right size, in this case, the excess is cut off from the inside.
Coaxial chimney Vaillant
Coaxial chimney for Vaillant gas boiler is included in the kit heating unit of this company. Matching the size of the pipes is the key to successful and long-term operation of the boiler. In addition, such chimneys can be purchased separately for boilers from other manufacturers.
Coaxial chimney Navien
The coaxial chimney for the Navien gas boiler from the Korean company has proven itself well in the heating equipment market. It is available for both wall-mounted and floor-standing boilers with a power of up to 75 kW. The price of the Navien coaxial chimney is lower than that of European competitors, but the quality of workmanship, judging by the reviews, is in no way inferior to them.
Coaxial chimney for Viessmann gas boiler
Its advantages:
- Natural heating of the intake oxygen in winter period time.
- The cost of a chimney and its installation is much cheaper than other types.
- Chimney installation requires less time.
The German company Vaillant, which specializes in the production of systems autonomous heating, has always been one step ahead of its competitors, offering consumers the latest technological solutions. She managed to achieve incredible success in a variety of niches of the household heating equipment market, including in such a specific area as the production of exhaust gas removal systems.
Today, Vaillant, being one of the industry leaders, is actively developing the direction of coaxial chimneys - a new global trend. In this article we will take a closer look at one of the latest developments by German engineers - the Vaillant 60x100 coaxial chimney, which is designed for units with a closed combustion chamber.
The design is made in the classic “pipe-in-pipe” format, which ensures efficient intake of fresh air and rapid elimination exhaust gases. The Vailant coaxial chimney ensures complete isolation of the processes of air supply to the firebox and smoke removal. Installing such a chimney not only helps maintain optimal levels of humidity and oxygen in the room, but also increases the efficiency of the boiler by several percent.
The operating principle of the Vaillant chimney, despite its perfect design, is quite simple. The pressurized burner, which is located in the boiler, exhausts exhaust gases to the street through an internal pipe, and through an external pipe of a larger diameter, fresh air is sucked from the combustion chamber.
This design is compact and easy to use and install. The Vaillant smoke extraction system cannot be compared to a traditional chimney. A coaxial pipe can be installed in absolutely any room, and quite quickly. To install a chimney in an apartment, you need to make a small hole in the wall for the unhindered removal of gases.
The versatility of the German Vaillant coaxial chimney is noted by many experts. It can be installed on either the right or left side of the boiler.
What is included in the installation kit? It includes:
- 90 degree elbow with a flange for aggregation with the boiler and specially provided holes that make it possible to take a sample of combustion products;
- 750 mm section of coaxial chimney;
- Cuffs for decorating the inter-wall passage;
- Installation kit for installing screws, gaskets and clamps.
Vaillant brand coaxial chimney is used for horizontal exhaust gases and rapid air flow into the combustion chamber. The total length of the structure is 1 meter.
Results
If you do not have the opportunity to equip a full-fledged exhaust gas removal system, this does not mean that your only choice is an electric water heating boiler. Today installation of gas or solid fuel boiler, requiring additional installation gas exhaust systems, possible in any room. The Vailant coaxial design, which has proven itself well among European consumers, will help you solve this issue.
Installation of a coaxial chimney requires a serious approach, as well as technical and theoretical knowledge. You should know all the requirements for fire safety, be able to follow these rules.
Only under this condition can the installation of a coaxial chimney be carried out successfully and safely. In this article we will talk about how to install a coaxial chimney from various manufacturers.
This article will cover the requirements and rules for the installation of chimneys “Baxi”, “Navien”, “Bosch”, “Vaillant” and others. The topic of how to install a vertical coaxial chimney will also be discussed.
Advantages and Disadvantages
The assembled coaxial chimney kit has the following significant advantages:
- Sufficiently high efficiency, which is ensured by the highly heated incoming air flow(this effect is especially noticeable in Baxi, Bosch, Vaillant and Navien chimneys);
- Compact design, ensured by one massive pipe (which, however, has an impressive diameter) instead of two in other types of chimneys;
- No need to add extra ventilation system(although in some cases it may be required in Baksi and Navien chimneys);
- The air circulating in the hotel system is absolutely safe for both humans and animals;
- Coaxial chimneys "Baxi", "Bosch" and "Vaillant" have the utmost low price drainage systems;
- No problems with condensate in the chimney system;
- Coaxial chimneys "Baxi", "Bosch", and "Vaillant" significantly reduce the overall fuel consumption for saunas and baths.
Another undoubted advantage of this type of chimney is the circulating cold air, which perfectly protects the walls of the building from possible overheating.
But this type of chimney also has a significant problem. We are talking about the possible risk of freezing of pipes that have a small diameter. The diameter of the pipes in this case plays a key role, since only pipes with a small diameter are susceptible to freezing.
And this problem is common for coaxial type chimneys manufactured by Baxi, Bosch and Vaillant.
Such frostbite occurs due to the fact that the temperature of the so-called “flue gases” when leaving the coaxial chimney becomes minimal, since it indirectly heats the inner pipe. And this subsequently leads to the formation of condensation.
It is for this reason that such freezing of pipes with a small diameter in coaxial chimneys is the norm.
However, when operating chimneys in Russian conditions, where the usual outside temperature quite often it is at -15 degrees Celsius and below, this can be fatal.
Even such advanced models of coaxial chimneys as Baxi, Bosch and Vaillant are not protected from this.
And moreover, there is currently a completely justified opinion that coaxial chimneys are generally not suitable for use in Russia. It’s no secret that they were originally created to work in the regions southern countries. Many people see this as the reason for freezing.
But there are also experts who think that such destructive freezing is just a problem of an initially incorrectly designed chimney and nothing more. In general, the debate has been going on for a long time, but there is only one conclusion.
It lies in the fact that the turbocharger, together with the galvanized chamber and the smoke exhaust burner, very quickly fail due to freezing problems.
Repairing them not only takes a huge amount of time, but also requires serious financial costs. And this is at a fairly high cost of the coaxial chimneys themselves!
However, from practice it can be seen that those models are usually subject to freezing heating equipment, in which, chasing the highest efficiency, the temperature of the flue gases goes off scale.
At the same time, it reaches the so-called “dew point”, for this reason the diameter of the chimneys is subsequently tried to be reduced to an absolute minimum.
The manufacturers of coaxial chimneys themselves answer all questions about freezing by saying that they were not created for such a climate. And it’s not that they weren’t created, but they were simply not tested for performance at average temperatures in Russia. And this must be taken for granted.
1.1 Installation of the chimney
Installation of coaxial types of chimneys does not differ from model to model. So chimneys such as “Baxi”, “Bosch”, “Vaillant” and others have the same general instructions.
At the same time, coaxial chimneys can only be installed in gas convector boilers and various radiators that have closed combustion chambers.
To install a coaxial type chimney, the following structural elements will be required:
- Knee:
- The actual smoke exhaust pipe (its length does not matter);
- Flange;
- Specialized adapter for the boiler;
- Crimp clamp.
The chimney should be installed at the shortest distance between the boiler and the wall. In this case, the entire length of the area from the boiler to the wall must be cleared of foreign objects and materials that can ignite.
It is also important to determine with utmost precision the point where the pipe will subsequently be discharged into the external environment (street). IN best case scenario the location of the pipe should be one and a half meters above the flue outlet from the boiler itself.
The holes should be made with a diameter of 110 - 125 millimeters. That is, to put it simply, just down the pipe. And here you can already understand that the requirements for the installation of coaxial types of chimneys are much less stringent than those of conventional models.
After installing the coaxial chimney, it is necessary to close the hole in the wall of the building with a specialized decorative overlay. It must be laid strictly according to the diameter of the pipe, for which you can use construction glue or so-called “liquid nails”.
In this case, the opening of the end from the street is most often foamed to prevent cold air masses from entering the boiler room from outside. Due to this, drafts and condensation can be avoided.
It is noteworthy that the coaxial chimney does not have to be routed through the wall of the building. In modern realities, it is quite possible to implement a scheme of so-called “collective chimneys”.
2 Fire safety requirements
There are quite strict and natural requirements and standards for the installation of coaxial types of chimneys. They are presented as follows:
- 0.5 meters horizontally directly to open various ventilation holes, windows and even doors;
- 1 meter vertically to all existing windows in cases where the chimney exits exclusively under them;
- 0.5 meters vertically to all existing windows in cases where the chimney exits exclusively above them (not to be confused with the previous point!);
- 2 meters from the ground, regardless of whether people walk on it or not.
In addition, when a gas pipe passes directly under a coaxial chimney, the distance between the pipe and the chimney must be no less than 20 centimeters.
At the same time, the distance from the corner of the house is no longer standardized or regulated in any way; there is freedom for improvisation and one’s own desires.
The most significant advantage of coaxial types of chimneys is, undoubtedly, the absence of the mandatory need to install additional ventilation in the boiler room. But here it is important to note that recently many experts recommend installing ventilation.
In any case, this will definitely not be superfluous and due to this it will be possible to significantly reduce the risks of fires and failure of the coaxial chimney.
2.1 Review of a coaxial chimney for a bath (video)
Choosing the optimal chimney for a gas boiler is not an easy, but completely achievable task. After all, you want it to be an extremely simple design to install and operate, and also with high efficiency. The coaxial type meets all the requirements, the installation of which can become a bit of a “snag”. Do you agree?
We'll help you figure it out complex issues. We provide site visitors with extensive information about the rules for constructing a coaxial chimney, about the selection and arrangement optimal option. Here you will find valuable advice for decorating sections of canals laid inside houses.
The article we have proposed describes in detail the standards for installing a coaxial chimney. Given useful diagrams for its proper assembly and installation. The information is confirmed and supplemented by photo collections and video tutorials.
In the family of devices for removing combustion products, the coaxial chimney stands apart. This modern design much more efficient and safer than a conventional chimney. This system is ideal for boilers with a closed combustion chamber.
To make a coaxial chimney, you need to take two pipes of different diameters and place the narrow pipe inside the wide one. Still need to connect inner side wide pipe and outside narrow pipe with special jumpers so that the central axes of both pipes coincide. Well, the coaxial chimney is ready.
In practice, such a design is, of course, easier and more reliable to buy than to make. The cost of a coaxial chimney will be higher than the price of an ordinary pipe made of stainless steel, but the costs will be fully recouped.
Image gallery
Updated:
2016-08-15
It's no secret that one of the main components of comfort in a home is warmth in it. A coaxial chimney will serve as a faithful assistant for solving this problem in private homes. This device for removing smoke from boilers is an effective replacement for outdated traditional pipes.
The design of a coaxial chimney (hereinafter referred to as KD) involves a design of a pair of pipes arranged according to the matryoshka principle. The pipe contours are connected by jumpers. The design itself is designed to work with heat generators closed type. An example of this is geyser. The inner pipe ensures the removal of combustion products, while the outer pipe serves to supply air from the outside. This allows you to forget about constant ventilation of the room. The price justifies the money, because boilers with pressure blowers, especially from the well-known company Baxi, are much more efficient than traditional ones, and at the same time they maximum length does not exceed 2 m in length. Most often, the CD is taken outside through a hole in the wall. Much less common is a vertical coaxial chimney that goes onto the roof.
In addition, there is a whole series problems that can be successfully resolved by installing a coaxial chimney:
- The compactness of the device allows you to save a lot of space;
- an impressive selection of CD models for systems of various capacities, the price of which may surprise no less than their quality;
- ecology and economy: thanks to high Efficiency system not only ensures complete combustion of fuel, but also reduces heat losses(due to heating of the air entering through the outer pipe with hot smoke in the inner one);
- the risk of fire of surfaces in contact with the coaxial chimney is significantly reduced (due to constant cooling of the inner pipe);
- After installing a coaxial chimney, additional ventilation of the room will not be required; the design eliminates the possibility of poisoning residents carbon monoxide, whether systems from Baxi or from other manufacturers.
Where does the installation of coaxial chimneys begin?
Before installing a coaxial chimney, you first need to choose the type of system - vertical or horizontal (including inclined). The price here is approximately the same, but please note that the latter option requires installation forced ventilation with the device. Besides, horizontal section the device should not exceed 3 m in length. Vertical CD is recommended if smoke will enter nearby nearby windows or into a narrow street. Always follow the diagram and instructions from the manufacturer (Baxi, Ochag, etc.) for a specific system, which describes the installation rules in detail.
For example, the ratio of the size of the boiler to the diameter of the outlet pipe is important; they must be equal to avoid overheating of the channel. And to ensure that combustion products escape unhindered, pipes, tees and elbows are attached by a specialist. It is better not to do the installation of a chimney yourself without having experience installing a coaxial chimney. It is easier to mount a vertical CD, the main thing is to stock up on brackets. The coaxial pipes themselves are connected into the system using a special transition unit. At the junction area, clamps are used to securely fasten the elements.
Chimney outlet and finishing work
The price of success is installation accuracy. When removing the pipe from the side of the heating device, there must be a horizontal section of the pressure pipe. In this case, the level of the pipe must exceed the level of both the boiler and the street by 1.5 m or more so that the pressure chamber does not become dirty. The angle of inclination of the outlet pipe is set from 3 degrees. This will prevent condensate from flowing back into the boiler. The pipe opening should be 60 cm or more from the window, and from gas pipes- half the diameter of the CD. In order to guide the device around an obstacle, you can use up to two differently inclined knees. The joint between the wall and the pipe must be insulated with non-combustible materials.
If the pipe is installed vertically on the roof, fire safety requirements must be taken into account. Use fire-resistant insulation, insulating pipes and special protective covers for the smoke exhaust duct. The pipe and the ceiling must be separated air gap. The outlet itself must be covered with a special apron that insulates the joint.
If a working CD is always cool, even when the geyser is working intensively, then the installation was carried out correctly. However, everything comes at a price: in cold climates, the device can freeze up. As a rule, this happens when it is positioned horizontally. In this case, you should contact the Baxi office or another manufacturer supplying heating products to purchase special protection.
Conclusion
To feel the desired comfort in your home, sometimes it is enough to know what a coaxial chimney is and how it is installed. In just a few days, as if by magic, your home will be transformed and life will become even more beautiful. You can install a coaxial chimney yourself, but if you have reasonable doubts about your abilities, it is better to hire an experienced specialist.
