Repair and construction

The chimney for a gas copper is coaxial, appointment, installation

July 31, 2020

Lots of ideas for that, how to heat the room are embodied in various inventions and technologies, which are successfully used today. Evidence of this is the emergence of modern autonomous heating systems, which are becoming more practical, economic mini factories for heat production. The system can run on many types of fuel, in the process of combustion of which combustion products are released, life threatening. Therefore, the efficiency of the boiler also depends on the efficiency of smoke outside the room.

Coaxial chimney is a modern system of removal of combustion products of heating boilers, including gas

Coaxial chimneys for boilers

Combustion is supported by air flow. During the operation of the furnace, air enters the furnace from the room, burning large amounts of oxygen inside, the room has to be ventilated, at the same time valuable heat is lost. This is how most households with a classic individual heating system are heated. Now began to use alternative heating systems with a closed combustion chamber (gas boiler, convector, radiator). In this case, the air supply and simultaneous removal of smoke is carried out by a coaxial pipe for a gas boiler - a technologically non-standard solution, not so long ago, but is already in demand. The progressiveness of the solution is, that the air in the boiler comes from the street through the same pipe, which removes combustion products. Two functions are performed by one pipe due to the peculiarities of its design.

And the peculiarity is this: coaxial chimney consists of two pipes. Smaller diameter pipe (60-110 mm) located in a pipe of larger diameter (100-160 mm) So, that they do not touch each other (have one axis) using jumpers along the entire length, which give the structure strength. The inner pipe is a chimney, and external is required for air flow. Circulation of air masses of different temperatures creates traction, streamlining their movement. Indoor air is not involved in the combustion of gas in the boiler, microclimate and heat are preserved.

Importantly! Coaxial chimneys are intended only for devices with a closed combustion chamber.

Material - steel (stainless, galvanized, enameled). The length of the coaxial chimney should not exceed 3 m, to prevent air flow vortices. You can also find information on limiting the length of the chimney in the instructions for the gas boiler, which must be taken into account, as the uninterrupted operation of the device depends on it. Reduced or extended diversion will not provide normal natural traction without electric boost.

The coaxial chimney consists of two pipes - the smaller part is inserted into the workpiece of larger diameter

The whole design is quite compact, mandatory kit includes:

  • coaxial pipe (there may be several);
  • coaxial angle (knee, withdrawal) 45, 90 city .;
  • tee;
  • adapter for connection to a gas boiler;
  • cleaning (section of the system for preventive work);
  • condensate collector;
  • chimney tip (protection against weather phenomena);
  • collar - fastener;
  • flange wall mounting;
  • sealing rings.

The design can be supplemented by details of the extension of the flue - coaxial pipes in length 0,5-1 m.

Another distinctive feature of the coaxial chimney from the usual - is the horizontal exit of the pipe outside the room, which saves a lot of space and gives more options for choosing the location of the boiler. Pipe, connected to the boiler (mainly with forced circulation of air masses), is displayed through the wall in a horizontal plane, reducing the cost of expensive chimney parts. If you lead the flue through the wall, it is not possible (near the window, the facade will be broken), the vertical conclusion through a roof is provided. The vertical position can also be mounted on the outside of the building wall, coaxial chimney, connected to the boiler, is displayed through a wall and upwards.

The coaxial chimney is designed to be serviced as a single boiler (individual), and several (collective). The individual is lined up in one line and has no branches, collective consists of individual branches of the coaxial system, removed on each floor of a multi-storey building and connected to a single pipe for the removal of combustion products.

In a multi-storey building, the flue is located vertically. It can be external (on the facade of the building) and internal (home mines, channels). The external chimney has constant access for repair and maintenance, however spoils the appearance of the structure.

The design of the chimney includes a lot of details, but the assembled design is compact

Positive aspects of coaxial chimney

We can name the following features of such channels:

  • significantly increases the productivity of the boiler: the fuel is completely burned due to the circulation of warm air streams. Cold air from the street, passing through the pipe, heats up, while the heated smoke comes out, thus maintaining the balance of temperatures in the chimney. This advantage also speaks of the environmental friendliness of the entire heating system (the level of emissions into the atmosphere is reduced);
  • fireproof. The outer surface of the flue does not reach the flash point (decay) adjacent materials. To increase safety, the pipes are insulated in contact with wooden surfaces, however, not as thorough as in the case of conventional metal flue. Unburned particles do not accumulate on the inner surface of the chimney, this eliminates ignition inside the pipe;
  • indoor, where the boiler is installed, comfortable temperature indicators remain, humidity, no harmful impurities in the air due to closed air exchange in the equipment through the coaxial pipe;
  • operation of a gas boiler with a coaxial chimney is economical, as fuel consumption is reduced, no heat loss;
  • does not take up much space in the room (especially relevant for small kitchens);
  • simple installation, different sizes of coaxial pipes and auxiliary parts facilitate their selection for boilers of any capacity;
  • the inner steel pipe is resistant to acids (combustion products in combination with condensate form destructive acids), can withstand temperatures up to 500oC, service life in compliance with all installation standards 25-30 years.

The downside of the coaxial chimney:

  • coaxial pipe for gas boiler is not insured against condensation, followed by icing at a temperature of 15oC;
  • in systems with forced air circulation, the operation of the chimney is disrupted in the event of frequent power outages or voltage fluctuations;
  • high cost, expensive repairs.

One of the disadvantages of this type of chimney is its freezing in winter, but this is often the result of improper installation

Installation of a gas flue gas boiler

Preparation for the installation of a coaxial chimney should begin with acquaintance with the rules and regulations:

For the collective system:

  • the flue must be installed only vertically and exceed the roof at a distance of at least 1,5 m;
  • the conclusion of a smoke by a single pipe with connection to it of branches from each copper. Ducts must not pass through living quarters;
  • the chimney of the basement is displayed at a height of at least 2 m from the ground;
  • the location of the chimney near the windows, doors or balconies are not desirable, although allow the distance in 1 m from the pipe to the window above it. Complaints of residents are inevitable.

Importantly! The conclusion of the coaxial chimney in the window pit of basements and semi-basements is not allowed.

For individual system:

  • vertical coaxial chimney in a one-story building should rise on 0,5 m above the ridge of the roof;
  • the outlet should be on 1,5 m above the furnace of the boiler;
  • the outlet channel must not be diametrically smaller than the boiler outlet;
  • distance from the chimney to the windows, doors, ventilation holes should be 0,5 m, if it is on the side or above them. If under them, then 1 and more meters;
  • the height of the horizontal exit of the chimney above the ground 2 m;
  • the distance from the head of the flue with a deflector to the blank wall of a neighboring house 2 m, to the wall with windows, doors 5 m. Without deflector 8 m;
  • protect the chimney from the wind, constantly blowing against the smoke will help the barrier (diaphragm) of sheet metal, located at a distance 0,4 m from the head;
  • the distance to the gas pipeline is not less 0,2 m.

The length of the chimney must meet the established standards

Coaxial chimneys for gas boilers are suitable for self-assembly. It will not be difficult to assemble the system if the instructions and safety measures are strictly followed. First of all it is necessary to define a place of installation of heating equipment so, so that the location of the pipe does not contradict regulatory restrictions. Then at the stage of calculating the amount of material, the following nuances of installation are taken into account:

  • the height of the chimney from the nozzle of the floor gas boiler to the wall opening is not less than one meter, from the wall - half a meter;
  • the system must not include more than two rotating parts;
  • the length of the horizontal section should not exceed one meter, vertical five meters. At forced draft the vertical site of a pipe should not be mounted, if it is displayed in the wall;
  • horizontally lying pipe is given a slope in 3 city. towards the boiler (condensing) or from the boiler (usual) preventing the accumulation of condensate;
  • the entire length of the flue system should not exceed three (five) meters;
  • the wall opening for the chimney is made with a gap 10 mm. The hole through flammable materials must have a gap 50 mm;
  • the joint of the chimney parts must be outside the thickness of the walls and floors;

Importantly! It is inadmissible to include in the composition of the coaxial chimney structurally unforeseen parts or parts from different manufacturers, self-made, with the presence of defects. It is forbidden to use adhesive joints and sealants.

Once the location is determined and the heating unit is installed, the hole on the same wall should be marked and drilled., to which it adjoins. Then the coaxial pipe is connected to the gas boiler (outlet pipe) by means of a collar with a bolt coupler. All elements of the flue system are connected by clamps according to the design plan, are fixed on a wall vertically by special arms. The horizontal section is installed in the hole. The gap between the wall hole and the pipe is filled with non-combustible insulation, from the street is insulated with foam. To make everything look aesthetically pleasing, the holes are closed with decorative overlays. The horizontal and vertical parts are connected by special swivel parts (angle, knee). The joints of the elements are complemented by heat-resistant rubber seals. The head of the vertical chimney should be protected from falling precipitation.

If the coaxial chimney for a gas boiler passes through combustible material (wooden walls, overlap) protective covers are used in places of contact, segments of asbestos-cement pipe in combination with insulation. It is recommended to increase the street length of the pipe to 0,6 m, to avoid contact of wooden walls with hot smoke. Although coaxial chimneys for gas boilers are NOT flammable, their surface does not reach the flash point, however, these fire protection measures should be used.

In the place of passage of the chimney through the wall must be installed ??heat-resistant plate

Installation is always carried out according to the manufacturer's instructions in accordance with the rules and regulations. After completion of installation work the system is checked for tightness of joints, pulling force.

Solving the problem of education and freezing of condensate

The main problem, which the owner of the coaxial chimney will have to face is condensate, formed at subzero temperatures outside. Presence in a design of a smoke removal capacity for collecting condensing moisture will prevent its hit in a copper and by that disturbance of its work.. Slope pipes on 2-3 city. towards the boiler will allow moisture to flow through the tee into the condensate drain.

Importantly! It is forbidden to discharge condensate into the ground, since it is a dangerous acid-containing substance.

Thermal insulation of the outer surface of the chimney of any type is considered mandatory, but in the coaxial chimney it does not solve the problem due to the design and principle of operation of the system. The issue of coaxial chimney insulation has caused controversy, initially such a measure was not provided by the manufacturer. It is carried out experimentally and does not give a clear effect. An even bigger problem is the freezing of condensate - freezing of the pipe head or the formation of ice plugs inside the chimney. If the deviation was made from the boiler (so that the condensate does not stagnate inside and drain out), then the solution may be to shorten the inner tube. There is a special nozzle - a module for protection against frost.

When designing a system, it is important to make the right calculation. So it depends on the length of the flue, what will be the outlet temperature. Exceeding the length will cause cooling of the flue and freezing of the formed condensate.

The problem with the formation of condensate can be caused by the installation of a heat unit with high productivity, where the chimney will not be able to provide normal traction, resulting in increased moisture production. Coaxial chimney is suitable for boilers with a capacity of up to 40 KW. Therefore, often the flue system comes complete with a boiler, and do not have to doubt them accordingly. A short horizontal exit of the pipe from the wall can cause condensate to get on the brickwork, what to avoid, as this will destroy the wall (condensate - an aggressive chemical environment with an accumulation of combustion products).

Although the operation of the coaxial chimney for a gas boiler is designed for mild climates, correctly performed calculations, compliance with the rules, norms and instructions will allow you to quickly and efficiently assemble a system with high efficiency, which will last a long time.