Coaxial pipe for the boiler: advantages, disadvantages and installation instructions

Modern gas boilers are reliable equipment that can provide us with not only warmth in the house, but also with hot water supply. But for their proper operation and high productivity it is necessary to install a special chimney. It must perform two basic functions at once: supply of oxygen to the burner and removal of combustion products from the premises. For this, a coaxial pipe is used. Let's talk about what it is and what its features are.

General information

We will not now talk about any design features of heat generators. It is enough to understand that for their effective operation a chimney is needed. There is the same situation as with the most common wood-burning stove. Of course, the coaxial pipe for the boiler has a completely different design, and its installation is carried out with its own nuances, which will be discussed below. So, the key feature of this chimney is that it works on the principle of "pipe in the pipe." It turns out that we have two pipes: one smaller, and the second larger diameter (outer and inner). According to one of them, oxygen enters the combustion chamber, and on the other, combustion products are discharged into the environment. A very effective solution, especially if you take into account the fact that such a pipe takes up very little space and is installed in one day.

About the advantages of the system

Coaxial gas pipe has a number of significant advantages, due to which it deserved such popularity. First, it is the localization of the combustion process, which is carried out by an isolated supply and discharge of air and, accordingly, combustion products. As a result, there is no mixing of oxygen and gas mixtures. Consequently, the productivity of the equipment increases.

Another plus - in the process of entering the boiler, the air heats up. This is achieved due to the fact that the pipe, through which it enters, is heated by waste products of combustion. In general, it is very effective, especially in the cold season. Of course, one can not ignore the fact that the design of a chimney "pipe in a pipe" in itself has smaller dimensions in comparison with a separate installation. This reduces the number of fasteners, and the complexity of installation is significantly reduced.

A little about the minuses of the system

Of course, there is no ideal system that does not have shortcomings. In our case, there are minuses, although some of them can be ignored, because they are insignificant, and others will have to accept.

The main drawback of such designs is that their cost is ultimately 20-40% higher than the installation of separate systems. Another problem is the concentric arrangement of pipes with hot and cold air. You probably noticed the icing on such pipes more than once. It is formed due to the accumulation of condensate and its freezing at minus temperature. Fight this with the installation of additional drain and insulation. But all this will further increase the price.

Well, the last drawback is the limited length of the coaxial tube. It's about 4-5 meters. Therefore, if your boiler is not installed near the window or there is no way to pull out the coaxial pipe for any reason, this option does not suit you.

About the regulatory framework

It is necessary to understand that you can not just take and install such a chimney, as the installation of a coaxial pipe is carried out taking into account existing requirements and norms. For example, there is a clear rule, which states that it is only possible to install chimneys through the roof. But this does not apply to individual heating, where you can mount horizontal coaxial chimneys. In general, the horizontal systems for the removal of combustion products and air supply can be installed only in private houses, and for multi-storey buildings vertical structures are envisaged that should rise 1.5 meters above the roof of the building.

Classification of systems

All modern coaxial chimneys are divided into internal and external chimneys. The first in residential buildings are practically not used. Such structures are mounted in special mines or old chimneys. But they must meet the requirements of fire safety. In addition, often the installation of such systems is very difficult, as well as maintenance.

Similar defects are lacking external coaxial chimneys. By the way, they are also classified according to the insulation. So, there are insulated and insulated. In regions where the air temperature does not fall below -10 degrees Celsius, chimneys can not be insulated. In other cases, there is a risk of partial or complete freezing of the pipes. In addition, there are individual and collective chimneys. The first are designed to serve one gas boiler, and the second - for a multi-storey building.

Structural composition and material of the chimney

The coaxial system is modular and consists of a large number of compositing elements. This includes an adapter for a gas boiler, straight pipe sections, connecting elements such as couplings and tees, and much more. True, components such as a coaxial tube extension, decorative lining, and may not be supplied in the kit - they need to be bought separately if necessary. But the mounting hardware and gaskets, ensuring the strength and tightness of the system, must necessarily be present in the kit. When installing such a system, it is desirable to use jumpers. They are necessary for fixing the inner tube relatively to the outer one.

As for the materials from which the coaxial tube is made, it is most often galvanized and stainless steel that can withstand high temperatures easily and does not undergo corrosion for a long time. In some cases, it is advisable to use heat-resistant plastic or aluminum. Often, for the consumer, it makes no difference what material the pipe will be made from, the main thing is to make the correct installation.

Features of chimney selection

In most cases, the coaxial pipe is supplied with the heating equipment, that is, with the gas boiler. That is why practically all manufacturers of heat generators produce similar chimneys. In the installation instructions for the equipment there is an item that indicates the maximum permissible length of the chimney. Under no circumstances can this value be exceeded. Otherwise, the efficiency of the equipment is significantly reduced. If the chimney operates on natural draft, that is, there is no fan in the boiler, then a parameter such as the minimum length of the pipe is entered. If you install a chimney smaller in length, then there will be no thrust and the combustion products will remain in your apartment or house. The diameter of the pipeline in the passport data is written as 100/140, where the first value is the diameter of the inner tube, and the second, respectively, the outer tube.

Mounting the coaxial pipe with your own hands

The first thing you should remember is the presence of no more than 2 folds in your chimney. When installing a horizontal system, place the pipe with a slope of at least 3 degrees. This is necessary for the condensate to drain by itself. If, however, the coaxial tube eventually joins with the common chimney, the angle must be changed in the opposite direction with a slope to the boiler.

The most important stage of work is drilling holes in the wall. Do this with the help of diamond equipment. But it is desirable to carry out such work if the house is being repaired, since there will be a lot of noise and dirt. After the hole is ready, it is necessary to lay the pipe, insulate it, and seal it. In general, there is nothing complicated. The main thing is that the chimney at the bends is well sealed. Also do not forget about the minimum slope, which is necessary for the drainage of condensate.

System Installation Rules

A vertical coaxial tube is mounted an order of magnitude simpler than a horizontal system. But to lead the chimney to the roof is not always possible. So, if you want the coaxial pipe to be installed correctly, you need to observe a few simple requirements.

So, you can not install the system below ground level. If the distance from the outlet to the ground is less than 1.8 meters, a deflector grille is installed to protect the pipe from dirt. If there are strong winds in your region, it is quite possible that the boiler will go out and not work at full capacity. Having installed a tin barrier, you can completely solve this problem. Of course, it is desirable to entrust such work to specialists who installed heating equipment, but if this is not possible, then, by observing these requirements, you will be able to manage on your own.

Conclusion

We talked about what a coaxial tube is. As you can see, this is a very effective and feasible in terms of productivity and space saving chimney. It is quickly mounted and serviced, which is without doubt an important point. If there is a need, you can install an extension coaxial tube, which will allow several to increase the total length of the chimney. Pay special attention to insulation, as often such systems are completely freezed. There is nothing good in this. Especially since this happens in the worst frosts. The problem though and dares quickly, but nevertheless it is better, that it was not. Now you can decide for yourself whether to use such a system or not. All the best!