The coaxial chimney for a gas boiler is a new technical solution that has replaced the standard options. It is used for heat generators with a closed combustion chamber (convectors, gas boilers). The main feature and great advantage of this chimney is that the combustion air does not come from the house, but from the street, into the boiler furnace.
Destination
The coaxial chimney for a gas boiler is designed to perform 2 functions at once:
- discharge of combustion products to the outside;
- providing an influx of fresh air, necessary to maintain the gas combustion process in the chamber.
Boilers with a closed combustion chamber, as a rule, are equipped with a chimney, the length of which is usually not more than 2 m. It should be noted that most often the chimney is installed on the street through the wall. Less common is the option when it is brought out through the ceiling and roof.
If the place in the wall where the chimney is supposed to be taken is located near the window, then it is best to place it just above the roof. However, in this case, it is necessary to mount the vertical part of the chimney.
Coaxial chimneys are installed in vertical and horizontal positions. They differ only in the installation method, and they work the same way.
Components
The coaxial chimney for a gas boiler consists of the following components:
- several straight pipes;
- tees;
- cleaning
- condensate collector;
- the top tip of the chimney;
- knee (angle 90).
A chimney is formed from straight pipes. The purpose of the knee 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, the following elements are included in its kit:
- straight pipes;
- knee (angle 90);
- chimney tip (side).
Coaxial chimney for a gas boiler, like all engineering systems, has its pros and cons.
The advantages of a coaxial chimney: customer reviews
- Oxygen to maintain the combustion process comes from outside, not from the room. This is the main advantage of a coaxial chimney. Its design includes two pipes, one of which performs the function of the outer, and the other of the inner shell. Through a pipe with a smaller diameter, combustion products - exhaust gases are discharged, and air is supplied to the combustion chamber of the boiler through an external pipe to support combustion.
- The design takes up quite a bit of space, which can significantly save indoor space.
- The chimney heats the incoming outside air with exhaust gases, which significantly increases the efficiency of the boiler.
- The system is fireproof. During removal, flue gases are cooled by the air entering the combustion chamber of the heat generator, which reduces the risk of a possible fire. Additional insulation of the chimney using flame-resistant materials is not required.
- Easy installation.
A similar chimney system can be installed on the following types of 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 of the installed chimney. His first models, which appeared on the markets, were not designed for low operating temperatures (-15 - -30 ° ), which can cause freezing of the structure and failure of the heat generator. 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 the wrong heat engineering calculation. If the chimney is correctly selected, it will not freeze.
When installing a vertical coaxial chimney, there is a problem of condensate collection. Since this disadvantage is known to manufacturers, certain models are equipped with a condensate collector.
Installation work
When you independently perform the installation of a coaxial chimney, you must definitely read the attached manufacturer's instructions and adhere to all recommendations:
- During installation, only those materials and components that have been tested in state gas supervision should be used; It is strictly forbidden to make any changes to the design and configuration of the chimney.
- When carrying out work, the use of materials that do not belong to the manufacturer of the chimney is strictly prohibited. All necessary additional components should be purchased only at a special service center.
- All parts of the chimney are connected and tested for flue gas leaks.
- It is forbidden to use sealants and adhesives.
- Joining pipes in the thickness of the wall is prohibited. The junction should be provided outside.
- The installation of a horizontal coaxial chimney is carried out (unless otherwise specified by the boiler manufacturer): for condensing units 2-3 ° towards it, for the classic version 2-3 ° from it, to remove condensate and prevent the ingress of precipitation into the boiler.
- The length of this chimney depends on the model of the boiler, the complexity of the chimney line.
- It is forbidden to carry the chimney exit equipment below ground level into the window pit of the semi-basement building.
- It is important to remember that during the operation of the chimney all responsibility for breakage and possible accidents rests with the installer.
Installation sequence
The chimney is attached to the boiler and taken out of the room. All excess and flammable objects are best removed before work.
Installation of a coaxial chimney of a gas boiler begins with the choice of a place for a thermal unit and a chimney. A gas boiler and a coaxial chimney are best installed together. The best option when the chimney is located 1-1.5 m above the boiler. If necessary, the chimney can be extended, but taking into account that there are no more than 2 elbows and their total height does not exceed 3 m.
Now you can start drilling holes of the desired diameter (within 11 - 12.5 cm).
Next, the pipe and the outlet neck of the boiler itself are connected. For this, a clamp is used, which is clamped on both sides by bolts.
The next stage of work is the assembly of the chimney of the required configuration. For all connections, clamps are used. The chimney that leaves the room must have a slight slope to remove moisture (condensate).
On this installation work is completed. It remains only for aesthetics to wear decorative overlays.
How to make a choice?
When choosing, first of all, you should pay attention to the recommendations that the boiler manufacturer provides. In some cases, service centers do not accept warranty equipment due to the installation of a coaxial chimney that is not recommended for this boiler.
The function of a coaxial chimney is to provide not only the exhaust of flue gases, but also the intake of oxygen from the outside, for this reason the reliability of its operation is very important. We offer to consider trusted foreign brands: Baxi, Vaillant, Viessmann, Navien.
Baxi Coaxial Chimney
It is made of stainless steel and high-strength polymer material. The standard kit includes a chimney pipe having a length of 1 m, a bend of 90 °, a nozzle that protects from winds, decorative rings. If necessary, you can purchase an extension cord. Please note 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 duct. This is necessary to compensate for draft, since the boiler fan power is designed for a certain chimney length (5 m). If there is no diaphragm, an excess amount of air will flow into the combustion chamber, thereby reducing the efficiency of the boiler. To avoid freezing, the coaxial pipe is installed so that its protrusion from the wall is not more than the length of the tip. When the length of the chimney exceeds the desired size, in this case, the excess is cut off from the inside.
Coaxial chimney Vaillant
A coaxial chimney for a Vaillant gas boiler is included in the heating unit of this company. Corresponding pipe sizes are the key to successful and long-term operation of the boiler. In addition, such chimneys can be purchased separately for boilers of other manufacturers.
Coaxial chimney Navien
The coaxial chimney for the gas boiler "Navien" from the Korean company has perfectly established itself in the market of heating equipment. It is available for both wall and floor boilers, the power of which is up to 75 kW. The price of the Navien coaxial chimney is lower than that of European competitors, however, judging by the reviews, the quality of execution is not inferior to them at all.
Coaxial chimney for gas boiler viessmann
Its advantages:
- Natural heating of the absorbed oxygen in the winter.
- The cost of the chimney and its installation is much cheaper than other types.
- The installation of the chimney requires less time.