Heating a house with a boiler requires two main requirements - a continuous supply of air to maintain the combustion process and the removal of combustion products. Today, the most effective, easy-to-use type of chimney is a coaxial pipe for a gas boiler. It is distinguished by high efficiency and operational safety.
What is a coaxial chimney
The structure of the chimney is such that a second short one is located inside the pipe with a greater length. There is also a condensate trap. The kit includes a set of knees, clamps, pads.
The purpose of the thin inner tube is to discharge the combustion products. The material for its manufacture is high-quality stainless steel. The role of the outer tube is to supply street air to the combustion chamber. From the side of the room, the pipes are connected to the boiler, and their opposite ends extend outside the room. Since the outer pipe does not have direct contact with hot gas and aggressive chemicals, cheap material can be used for its manufacture.
This type of chimney is used in boilers that support open combustion of fuel. Where a traditional stove chimney cannot be used for various reasons, a coaxial one is installed. For safety reasons, it is not recommended to connect gas boilers to old furnace channels.
For example, this option is used in apartments with individual heating. The boiler can be installed on the ground floors, while the pipe is mounted in a horizontal position, and the draft is provided by the built-in turbine.
Manufacturing material
In the manufacture of a coaxial chimney, two types of material are used - stainless steel and plastic
Plastic
The main advantage of the plastic system is its affordable price. PVC pipes are lightweight, which greatly facilitates their installation. However, the service life of such a product will be lower than that of a high-quality stainless steel pipe. The best solution would be to use a combined material - an inner pipe made of stainless steel and an outer one made of PVC.
Stainless steel
The advantage of the stainless steel pipeline is the high temperature resistance of the material. Stainless steel is much better than plastic withstands exposure to high temperatures and condensation with an aggressive chemical composition. If the system uses food grade stainless steel, you can be sure of the durability of the pipe.
To reduce the amount of condensate and quickly evaporate it from the inner surface, the structure is insulated or a finished product with insulation is purchased.
Types of coaxial systems
Vertical
This type of chimney is used exclusively for private housing construction. The tube passes through the ceilings, the roof and is taken out to the top. In terms of ecology, this option for the removal of combustion products is more environmentally friendly. Plus, this method provides natural traction.
A plastic or metal condensate receiver must be installed at the bottom of the pipe. The vertical version of the chimney installation for a boiler with a closed combustion chamber is more expensive and laborious.
Horizontal
The horizontal installation method is the only available option for an apartment. This method requires minimal material consumption. The negative pipe slope ensures natural condensate drainage.
Installation rules
- Outside, the distance between the ground and the pipe must be at least 2 meters.
- The free distance from the chimney to other elements located in the room must be at least 50 cm.
- The distance from the bottom of the window to the ventilation opening at the bottom must be more than 100 cm.
- On the outside from the ground to the pipe, there must be a free space with a height of at least 150 cm, not occupied by a fence, pillars or adjacent walls.
- In order for the condensate to drain directly to the ground, the chimney is mounted with a slope of 3 - 12 degrees.
- It is not allowed to lead the pipe into an adjacent room. Only on the street.
- The distance between adjacent pipes must be at least 20 cm.
For self-production and installation of a coaxial chimney, you will need to purchase:
- pipes of the required diameter;
- adapters for connecting pipes to the boiler;
- tees and elbow.
Reliable fixation of parts is performed using crimping clamps. When buying a chimney, the kit includes all the necessary elements for assembling and fixing the structure.
In the places where the pipe passes through the structures of the house - in ceilings, roofs and walls - insulating fire-resistant gaskets are used. They protect materials that come into contact with a heated chimney from overheating and fire.
Advantages and disadvantages of coaxial chimneys
If we compare a coaxial chimney with other varieties, its advantages are obvious:
- A closed system is used to supply clean air into a closed chamber. Therefore, the air from the room where the boiler is installed is not consumed.
- When using such a scheme, the probability of penetration of dangerous carbon monoxide into the room is excluded.
- The system does not affect the formation of a draft in the room, changes in humidity, temperature, and other microclimate parameters.
- With such a chimney, the gas boiler gains increased performance. At the same time, natural gas is consumed in an economical mode, and the volume of harmful substances in the environment is reduced.
- The chimney does not come into contact with nearby structures and materials, due to the presence of a protective casing and an air layer.
If the manufacturer's recommendations are followed during the installation and operation of such a system, there is no likelihood of emergency situations. Another pleasant plus is the affordable cost of such a chimney.
The only drawback of a coaxial pipe is the freezing of condensate in cold weather in the section of the pipe located outside. This issue is easily solved by additional insulation with mineral or basalt wool. Some models are equipped with a special head. Experts do not recommend shortening the pipe.
