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How to choose the right chimney?
This question is of interest to many people who sell or professionally install chimneys, are building their own houses, summer cottages or baths.
We bring to your attention a number of tips from the Teplov and Sukhov company on how to choose the right chimney.
The first is the choice of steel.
When choosing a steel grade for a chimney, it is imperative to take into account the characteristics of the heating unit used, the operating mode, the type of fuel and the temperature of the flue gases, therefore we strongly recommend focusing on such metal indicators as temperature resistance and corrosion resistance. Strength, heat resistance, heat resistance (please note that heat resistance and heat resistance are different concepts) and other properties of steels depend on the content of the main alloying elements (manganese, chromium, nickel, titanium, etc.). In chimney systems, austenitic and ferritic stainless steels with different alloying elements are used, which makes it possible to make the best choice - to choose a steel chimney for any heating unit, operating mode and type of fuel.
With the same steel grade and chimney diameter, it is preferable to use a metal with a greater thickness, which to a greater extent affects:
- the service life of the chimney associated with the corrosion of the flue duct (heat resistance);
- bearing capacity along the vertical axis of the chimney, the loads on which increase in accordance with the increase in diameter and the effect of elevated flue gas temperatures (thermal strength).
The second is the connection of the chimney pipes.
The main problem for pipes with a seam connection is the assembly of the chimney elements together. Due to the increase in thickness (in 4 layers) in the place of the seam joint, it is not possible to achieve a tight fit of the metals of the chimney elements along the entire perimeter, and the thicker the metal of the chimney wall itself, the larger the gap, as a result, the low tightness of the chimneys.
The disadvantages of a corrugated connection include the following:
- forced narrowing of the smoke channel at the junction of the chimney elements with each other, and as a result - the appearance of turbulent eddies at the junctions with soot settling;
- inability to install sealing silicone rings - for chimneys working under pressure;
- less reliability of fastening at the junction of the chimney elements with horizontal and vertical loads on the chimney.
The advantages of a socket joint:
- the diameter of the chimney is the same along the entire length of the chimney - there is no change in the flow area;
- high tightness of the chimney;
- clamps on chimneys with a socket joint perform a double function - they fix the elements of the chimney together and tighten them, increasing the tightness of the smoke channel;
- additional ability to install sealing rings and operate the chimney under pressure
- simplicity and convenience of chimney assembly.
Teplov and Sukhov recommends to ALWAYS use the connecting clamps of the chimney elements along its entire length.
The third is the type of welding of the chimney elements.
Butt welding allows you to achieve the exact geometric dimensions of the chimneys in diameter and the minimum error in the thickness between the weld seam and the chimney metal itself, which is of great importance during assembly.
A wide range of adjustable parameters for automatic TIG and laser welding allows you to exclude defects typical for this process, such as undercuts, burn-throughs and non-penetration.
In automatic butt-welding of chimneys, filler wire is used for welding stainless steels containing nickel and chromium. This makes it possible to obtain a weld seam even more alloyed than the base metal of the chimney in ferritic steels.
The process of welding in an environment of shielding gases (Ar) on all sides of the seam excludes the interaction of the metal of the weld pool with oxygen, which is an oxidizing agent and contributes to the burnout of alloying elements of the metal.
The fourth is the way of packing the chimney elements.
Packaged goods mean the reliability of the safety of the goods, the absence of damage during transportation, and the convenience of storage in the warehouse and in the store. This is what differentiates customer-centric manufacturers from manufacturers in general.
When choosing a chimney, pay attention to these features, this will allow you to avoid many troubles in the operation of the chimney.
Fifth - product labeling and bar-coding.
Marking and barcoding is essentially the pedigree of each element. Their presence indicates that the manufacturer is careful about storing information and has nothing to hide from the buyer. What distinguishes the Teplov and Sukhov company is that we apply product marking with a laser. This allows you to save information about the manufacturer and the product during the operation of the chimney. The laser barcode does not fade, which happens to the paper label stuck on the outside of the elements.
Sixth is isolation.
Chimney insulation fulfills the main tasks:
In the shortest possible time, bring the chimney to operating mode
Protect the outer circuit of the flue from high temperatures of the inner circuit.
When interacting with the environment, condensation forms on the inner surface of the pipe. Condensation is one of the most harmful phenomena for chimneys. During the furnace, flue gases passing through the chimney inevitably cool down, water vapor on the walls of the chimney condenses (turns into water), dissolves soot in itself, that is, it combines with the products of fuel combustion in the boiler (in a gas boiler - CO, CO2; in liquid and solid fuel boilers and fireplaces, besides this also sulfur compounds), forms the corresponding acids or their mixtures. These acids include hydrochloric, nitric and sulfuric acids. In some cases, a mixture of them may form.
Therefore, thermal insulation plays a vital role, insulation is necessary in order to reduce the likelihood of a "dew point" - the formation of acid condensate.
The higher the operating temperature of the chimney and the cyclicity of the furnace, the more effective the heat-insulating layer should be, and the increase in the thickness of the thermal insulation.
When working on gas, the thickness of the chimney insulation must be at least 25-30 mm
With a wood-burning firebox - 30 ... 100 mm.
Even when using a chimney with a large insulation thickness, one should not forget about fire safety measures, because even in this design, the outer circuit of the chimney can be heated to high temperatures. The recommended distance from the chimney to combustible surfaces in the "line of sight" is 500 mm. *
When laying a flue duct in the open air, Teplov and Sukhov recommends ALWAYS use a heat-insulated chimney in order to increase its durability and, as a result, safety.