Coaxial chimney for gas boiler: installation, device and feedback (photo)

A 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 in the boiler furnace comes not from the house, but from the street.

Purpose

Coaxial chimney for a gas boiler is designed to perform 2 functions at once:

• Combustion products outward;
• Ensuring the influx 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 not more than 2 m. It should be noted that most often the chimney is installed on the street through a wall. Less common is the option, when it is taken outside through the ceiling and the 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 way they are installed, and they work the same way.

Components

The coaxial chimney for the gas boiler consists of the following components:

• Several straight tubes;
• Tees;
• Cleaning;
• Condensate collector;
• The upper tip of the chimney;
• The knee (angle 90).

From the straight pipes form a chimney. The purpose of the knee is to connect the horizontal chimney with its vertical part, and also the gas boiler.

If the chimney is located only in a horizontal position, its kit includes the following elements:

• Straight pipes;
• Knee (angle 90);
• The tip of the chimney (lateral).

A coaxial chimney for a gas boiler, like all engineering systems, has its pros and cons.

Advantages of 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 performs the function of the outer, and the other of the inner shell. Through a pipe with a smaller diameter, the combustion products are exhausted - exhaust gases, and air is supplied through the outer tube to the combustion chamber of the boiler to support combustion.
• The design takes up quite a bit of space, which saves considerable space inside the building.
• The chimney heats the incoming outside air with exhaust gases, which significantly increases the efficiency of the boiler.
• The system is fireproof. When venting, the flue gases are cooled by air entering the combustion chamber of the heat-generating unit, which reduces the risk of a possible fire. It is not necessary to produce additional insulation of the chimney with the use of difficult flammable materials.
• Ease of installation.

Such a chimney system can be installed on the following types of boilers:

• On gas;
• On solid fuel;
• On liquid fuel.

Disadvantages of coaxial chimneys

Freezing. According to users, this is the most important and serious flaw in the installed chimney. Its first models, which appeared on the markets, were not designed for low operating temperatures (-15 - -30 ° C), which can cause frost in the structure and failure of the heat generating unit. A 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 a wrong heat engineering calculation. If the chimney is properly selected, it will not freeze.

When installing a vertical coaxial chimney, there is a problem of collecting condensate. Since this drawback is known to manufacturers, certain models are equipped with a condensate collector.

Installation work

In case of independent installation of the coaxial chimney, it is necessary to familiarize yourself with the manufacturer's instructions and adhere to all the recommendations:

• During installation, only those materials and components that have been inspected in the State Audit Office should be used; It is strictly forbidden to make any changes to the design and configuration of the chimney.
• When carrying out work, use materials that are not owned by the manufacturer of the chimney, is strictly prohibited. All the necessary additional components should be purchased only in a special service center.
• All parts of the chimney are connected and tested for flue gas leaks.
• It is forbidden to use sealants and glue compounds.
• Docking pipes in the thickness of the wall is prohibited. The place of the joint should be ensured beyond its limits.
• 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 classical version 2-3 ° from it, to remove condensate and prevent the penetration of sediments into the boiler.
• The length of this chimney depends on the model of the boiler, the complexity of the chimney line.
• It is prohibited to conduct the chimney outlet equipment below the ground level in the window pit of the semi-basement building.
• It is important to remember that during the operation of the chimney all responsibility for the breakdown and possible accidents is assigned to the installer.

Sequence of installation

The chimney is attached to the boiler and the rooms are taken out. All unnecessary and flammable objects should be removed before work.

The installation of the coaxial chimney of the gas boiler starts with the selection of the location for the heat unit and chimney. A gas boiler and a coaxial chimney are better to be installed together. The best option when the chimney is located above the boiler is 1-1.5 m. If necessary, the chimney can be lengthened, but taking into account that the knees were not more than 2, and their total height did not exceed 3 m.

Now you can start drilling holes of the desired diameter (within 11 - 12.5 cm).

Further, the pipe and the outlet throat of the boiler itself are connected. For this, a clamp is used, which is clamped on both sides with bolts.

The next stage of the work is the assembly of the chimney of the required configuration. Clamps are used for all connections. The chimney that exits the room must have a slight inclination to remove moisture (condensation).

This completes the installation work . It remains only for the aesthetics to wear decorative lining.

How to make a choice?

When choosing, first of all, it is necessary to pay attention to the recommendations provided by the boiler manufacturer. In some cases, the service centers do not accept the equipment for warranty because of the installation of a coaxial chimney not recommended for this boiler.

The function of the coaxial chimney is to provide not only the flue gas outlet, but also the intake of oxygen from the outside, for this reason the reliability of its operation is very important. We offer to consider the tested foreign brands: Baxi, Vaillant, Viessmann, Navien.

Coaxial chimney Baxi

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 90 ° elbow, a windproof headpiece, decorative rings. If necessary, you can purchase an extension cord. It should be borne in mind that a coaxial chimney for a gas boiler Baxi, the length of which is up to 1 m, requires the installation of a narrowing diaphragm on the duct of the boiler. This is necessary to compensate for the thrust, since the power of the boiler fan is calculated for a certain length of the chimney (5 m). If there is no diaphragm, an excessive amount of air will enter the combustion chamber, thereby reducing the efficiency of the boiler. To avoid frost, the coaxial tube 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.

Chimney coaxial Vaillant

Coaxial chimney for gas boiler Vaillant is included in the set of the heating unit of this company. The correspondence of the dimensions of the nozzles is the key to the successful and long-term operation of the boiler. In addition, such chimneys can be purchased separately for boilers of other manufacturers.

Chimney coaxial Navien

The coaxial chimney for the gas boiler "Navien" from the Korean company has perfectly proved itself in the market of heating equipment. It is available both for wall and floor boilers, whose power is up to 75 kW. The price of the coaxial chimney "Navian" is lower than that of European competitors, but the quality of performance, judging by the reviews, while not inferior to them.

Coaxial chimney for gas boiler viessmann

Its advantages:

• Natural heating of the absorbed oxygen in the winter period of time.
• The cost of the chimney and its installation is much cheaper than other types.
• It takes less time to install the chimney.