We select a chimney for a gas boiler: types, calculation, step -by -step installation instructions

For a gas boiler, selecting the appropriate chimney is essential to guaranteeing efficiency, safety, and regulatory compliance. A chimney influences the operation of your gas boiler in addition to venting the combustion gases. There are various chimney types to take into account, each of which is appropriate for a particular installation scenario and boiler type.

To start, it’s critical to comprehend the various kinds of chimneys that are available. Prefabricated metal chimneys, flexible stainless-steel liners, and masonry chimneys are common choices. Although they require careful construction, masonry chimneys are traditional and long-lasting. Prefabricated metal chimneys fit different boiler configurations and are simple to install. Relining existing chimneys with flexible stainless-steel liners can increase efficiency.

It’s important to determine the chimney’s size before choosing one. To ensure adequate gas venting, the size should correspond with the boiler’s output. This computation takes into account variables like the BTU rating of the boiler, the chimney’s diameter and length, and local building codes. Inadequate venting caused by incorrect sizing may result in safety risks or lower boiler efficiency.

It’s crucial to install your chimney correctly once you’ve decided on its size and type. Usually, there are multiple steps involved in installation. Prior to mounting, make sure the area is ready and that all flammable materials are clear. After that, assemble the chimney’s parts in accordance with the manufacturer’s instructions, making sure to provide adequate support and tight seals. Lastly, make sure the chimney and boiler’s flue outlet are securely sealed together.

A proper installation also involves checking for any debris or nests that might obstruct airflow. Make sure the chimney has all the required accessories, such as draft diverters to maximize airflow and rain caps to stop water intrusion. By following these installation guidelines, you can prolong the life and improve the efficiency of your gas boiler system in addition to ensuring compliance with safety regulations.

Types of Chimneys There are various types of chimneys suitable for gas boilers, including single-wall metal, double-wall metal, masonry, and flexible liners.
Calculation Calculate chimney size based on boiler output, fuel type, and local building codes to ensure proper ventilation and safety.
Step-by-Step Installation Install chimneys carefully by following manufacturer instructions, ensuring correct angles, supports, and sealing to prevent leaks and ensure efficient exhaust.

Requirements for chimney for gas boilers

Regulatory documents that outline the fundamental specifications for these designs govern the design, assembly, installation, and other actions related to the installation of the chimney channel.

The DBN in.2.5-20-2001 "Internal gas supply device" and SNiP 2.04.05-91 "Heating, ventilation, and air conditioning" are normative documents that regulate the device of chimneys for gas boilers.

The requirements listed below are given to smoke structures that will be used in conjunction with heating boilers based on these documents:

  • The section of the chimney can not be less than the output pipe of the gas boiler. For example, if the pipe has a section of Ø150 mm, then the minimum diameter of the chimney should also be at least 150 mm. For the entire length of the chimney, the pipe should not have narrowed areas and curvatures;
  • The location of the chimney – the chimney should go strictly upward. If necessary, a slope of 30 about . In this case, the length of the bends can be no more than 100 cm, and their maximum amount is not more than 3. If the pipe rotation is required, then the radius of rounding should be larger or equal to the diameter of the pipe used;
  • The height of the chimney above the ridge is at least 0.5 m in cases where the pipe is located at a distance of 1.5 m from the roof skate. If this distance is from 1.5 to 3 m, then a pipe device is allowed with a barrel with a skate level. In other cases, a conditional line is drawn from the level of the ridge at an angle of 10 about . The head of the pipe should "touch" this line. The distance from the ovation of the roof to the chimney – at least 1.5 m;
  • Materials – only non -combustible gas -resistant materials are used for the manufacture of the chimney. When increasing the structure, the upper part of the pipe should be worn on the lower link. In this case, the place of contact must be treated with non -combustible sealant;
  • device – the minimum distance from the chimney to objects and surfaces made of flammable materials should be at least 25 cm. In other cases – at least 5 cm. When passing the chimney through the ceilings and the roof there should not be direct contact of the chimney with these structures. At the bottom of the chimney, the revision module with a dropper is necessarily mounted.

The aforementioned conditions are standard and need to be met without fail in every situation. When installing the chimney, keep in mind that even minor variations from the specifications listed in the regulatory documents can shorten the chimney’s service life and, in certain situations, have more detrimental effects.

Boilers and output of the chimney

In terms of structure, a gas boiler is a device that consists of a heat exchanger that gets heated by the energy released during the combustion of the gas and a gas burner into which gas is introduced through nozzles. The upper chamber contains the gas burner. Pumps that rotate in a circular motion move heat.

Furthermore, many self-diagnosis and automation modules are included in contemporary gas boiler types, enabling the use of equipment in autonomous mode. Consider the boiler’s type of combustion chamber when selecting a chimney. The best kind of chimney will depend on its design since it is specifically on this that determines the air intake method, which is required for gas combustion.

Gas boilers can have one of two types of combustion chambers:

  • open – provides natural traction. Air fence comes from the room in which heating equipment is installed. The removal of combustion products is carried out by means of natural traction using a chimney with output through the roof;
  • closed – provides forced traction. Air fuel burning fuel occurs from the street. In rare cases, air can climb from a special room equipped with supply ventilation. For the simultaneous removal of furnace gases and a fence of fresh air, a coaxial chimney is used, which is excreted through the nearest supporting wall.

It’s easy to select or create a chimney that fits the furnace chamber type if you know what kind it is. In the first scenario, an ordinary thin-walled or insulated chimney is used when the boiler has an open combustion chamber.

An arrangement of pipes with varying diameters is known as a coaxial chimney, and it is utilized with boilers that have closed combustion chambers. Through the use of unique racks, the pipe with the smaller cross section is fixed inside the pipe with the larger diameter. Carbon dioxide and other combustion products are eliminated on the internal channel, and fresh air enters a closed top-throat chamber through the space between the outer and inner pipes.

Ways to install chimneys

The chimneys are classified according to the device method into:

  • internal – chimneys made of metal, brick or ceramics. Are both single -walled and insulated two -walled structure. They are located vertically up. The presence of several knees with a displacement of 30 o;
  • external-coaxial or sandwich dummies. Are also located vertically upwards, but the chimney is excreted through the supporting wall horizontally. After the pipe was removed, a rotary knee is installed 90 O and support brackets, allowing installation in the right direction.

The size of the building where the equipment is located should be considered when selecting the chimney installation technique. External chimneys are preferable for small buildings because they enable the chimney to be removed from the interior.

In other situations, you ought to develop your own strengths. The internal chimney will be the best option if there is enough room and high-quality insulation can be installed where the pipe passes through the ceiling. particularly if the pattern is encased in brick or shielded by a ceramic box.

For gas boilers, selecting the appropriate chimney is essential to both efficiency and safety. This article looks at different types of chimneys that work well with gas boilers, explains the calculations that are necessary to make sure the ventilation is adequate, and offers a simple, step-by-step installation guide. Whether you’re building a new chimney or replacing an old one, knowing these things will guarantee that your gas boiler works efficiently and reduce the risks related to poor ventilation.

DIY chimneys for gas boilers

A chimney for a gas boiler can be bought from specialty stores, just like other heating appliances. This will be a standard modular product that is chosen based on the power and type of boiler.

What to make a chimney for a gas boiler

A gas boiler chimney can be constructed from a variety of materials. What matters most is that the material doesn’t burn, can withstand harsh chemical environments, and doesn’t absorb smoke-channel gases.

The following materials are used in the manufacture of the chimney due to regulatory requirements:

  • brick – traditional material for the manufacture of chimneys of solid fuel furnaces. For masonry, the chimney use the fire -resistant brick of class A or B. When using gas equipment, a combined approach is often used, when a steel or asbestos -cement pipe is used as an internal channel;
  • steel – used to create chimneys of any configuration. The quality and heat resistance of the material determines its alloy, which indicates a special marking. So, products made of steel AISI 316i, AISI 321 or AISI 310S are better suited for the manufacture of chimneys;
  • Ceramics – a burned mixture of clay and sand from which combined chimneys are made. The internal channel is made from a ceramic pipe of a certain section. As a protective casing, a clay -concrete shell or brick box is used.

A thorough comparison reveals that the AISI 321 and AISI 310S brands of galvanized steel offer the best value in terms of both price and quality. These steel chimneys are intended to withstand furnace gas temperatures of up to 800 and 1000 O, respectively.

Steel chimneys typically last 13 to 17 years, but because of their high degree of component unification, you won’t need to entirely replace the structure. Only a portion of the burned modules are replaced during the repair.

Ceramic chimneys are significantly more expensive than their steel counterparts, despite having excellent operating characteristics and a service life of more than 50 years. Because of this, installing this kind of chimney is only advised if one has ample money and intends to construct the structure for an extended period of time. The utilization of gas equipment in conjunction with brick chimneys is not warranted in terms of labor expenses or the overall cost of the building.

How to calculate the parameters of the chimney for a gas boiler

Calculating the chimney’s cross-sectional area and height in relation to the skate’s level is essential for making or selecting a chimney correctly. The entire height of the chimney is chosen in compliance with the SNiP 2.04.05–91 regulatory guidelines.

Table: Dependence of the cross -section of the chimney on the power of the gas boiler

The section of the chimney, mm Peak power of a gas boiler, kW
120 24
130 thirty
170 45
190 55
220 80
230 100

The following formula is used to determine the pipe’s cross-section: f = (k ∙ q) / (4.19 ∙ √ˉ n), where:

  • K is a constant value, the value of which varies from 0.02 to 0.03;
  • Q is the maximum productivity of gas equipment specified in the specification;
  • H – calculated height of the chimney according to SNiP.

The chimney for gas boilers needs to be at least 5 meters high. The height in relation to the skate is chosen using the guidelines outlined at the outset of the article. Remember that you should be at least 0.5 meters tall in relation to the skate.

Following the design of the pipe area, the value that is obtained must be compared to the information presented in the table. The computed smoke channel diameter is rounded to the higher value if needed.

DIY chimney installation

Single-circuit steel pipes or special sandwich tubes with the required diameter are used to assemble the chimney. If the first option is chosen, insulation of the chimney is advised after it has been assembled. In the second scenario, there is no need to insulate the chimney thermally.

We provide the technology for installing a steel chimney for a gas boiler as an example. The chimney assembly requires straight steel pipes that are 50 or 100 cm long, a 30 o chimney, a passage box for the walls and ceilings, a deflector, squeezing clamps, and heat-resistant sealants.

When the output pipe’s diameter differs from the chimney’s diameter, the proper adapter is utilized. Cotton wool made of basalt is a better material for isolation.

The steps involved in installing a chimney for a gas boiler are as follows:

  1. A single -walled or insulated pipe is carried out to the output pipe of the gas boiler. To do this, the pipe is missed by a heat -resistant sealant, after which an adapter is put on it, which is tightened by a squeezing clamp.
  2. A similar approach is used to connect the adapter with the pipe. First, the editing end of the adapter is treated with sealant. Next, a straight pipe is planted on it to the desired depth. After which the connection is tightened with a clamp.
  3. To remove the chimney through the ceiling, you need to cut a square of the square section in it. The size of the hole is selected in such a way that a distance of at least 20 cm remains from the chimney to the overlap.
  4. A steel box is mounted in a drunk on the ceiling. For fastening, steel screws of 30-50 mm long are used. Then a pipe is passed through the box, which is mounted on a module connected to a pipe. The space between the pipe and the box is filled with a mineralized heater. The box is closed with a steel plate on top.
  5. If after entering the pipe into the inter -shallow space it requires its displacement, then the knee 30 O is installed according to the scheme described above. In other cases, the direct section of the pipe is installed.
  6. To remove the chimney through the roof, similar actions are performed. First, a hole of the square section is cut out the right size. Next, the installation of the mounting plate with the opening for the pipe is installed. Then a straight section of the chimney is mounted. In conclusion, a conical diving element of steel or non -combustible plastic is put on the chimney pipe.
  7. At the final stage, the remaining area of ​​the chimney is carried out. At the end of the pipe, the head is installed and the deflector. After the assembly, the performance of the assembled design is checked. To do this, it is enough for the equipment to work at 50-60% of the maximum power within one hour.

An external chimney installation requires a rotary knee 90 about. The adapter, which is likewise fixed on the gas boiler pipe, is directly connected to the knee.

It will be necessary to drill a hole in the bearing wall for the chimney’s output. The hole’s size is chosen in a similar manner to that of the roof and ceiling. After that, a steel box is affixed to the wall and a pipe is run through it. Mineral wool or basalt is used to fill the box.

Another knee of about 90 degrees is needed for the pipe to rotate repeatedly. A unique support with a bracket is used as a supporting structure and is positioned beneath a rotary knee. Installing suspended brackets: 1 to 1.5 meters. Similar actions are required in the future: a chimney must be collected from straight products that are connected with clamps and sealants.

Coaxial chimney for a gas boiler with your own hands

Prior to installing a coaxial chimney, make sure the item you purchased is complete. Should there be none, you ought to swap out the incomplete kit for a full one that comes with the following items:

  • pipe with a flange;
  • coaxial knee 90 o;
  • connecting adapter;
  • wall overlays;
  • sealing rings;
  • connecting clamps;
  • decorative socket;
  • Fixed screws.

The following steps are involved in installing a coaxial chimney:

  1. The inner knee of the coaxial pipe with the output pipe of the gas boiler is carried out. To do this, a heat -resistant sealant is applied to the pipe and a connecting adapter is put on. To fix the adapter, a connecting clamp is used, which is delayed using a cross or slotted screwdriver.
  2. For the output of the coaxial pipe, a hole is drilled through the wall, the diameter of which should be 1.5–2 cm larger than the diameter of the chimney. To do this, use a punch or an electric drill with a crown nozzle. When drilling, you should follow the slope towards the street in 2-3 about .
  3. Next, an asbestos pipe is installed in the hole. The space between the pipe and the wall is filled with insulation. A decorative lining is mounted from the house. A coaxial pipe is passed through the prepared hole, which is connected to the rotary knee on 90 o .
  4. On the side of the street, a protective-decorative nozzle is put on the pipe, which is screwed to the surface of the wall with self-tapping screws. At the end of the coaxial pipe, a special deflector or protective overlay from freezing is put on.

The components of the installation set for the chimney may vary slightly depending on the manufacturer, but the kit must include the essential components—a knee, pipes, clamps, and linings. Reviewing the installation instructions is highly advised prior to installing a coaxial chimney.

Video: a chimney for a gas boiler from a sandwich pipe

How to reduce the temperature of the smoke gases in the chimney

As natural gas is burned, carbon dioxide, steam, and oxides that form sulfur are produced. D. The flue gases should exit the chimney at a temperature between 100 and 110 °C.

The water vapors in the combustion products will settle on the chimney walls if the temperature of the outgoing gases is lower than the dew point, or the temperature at which air condensation occurs. Should this occur on a regular basis, the chimney may collapse very quickly.

Furthermore, the natural traction in the smoke channel is weakened due to the continuous presence of condensation. Because the temperature of the outgoing gases directly affects the section of the chimney, it is crucial to keep an eye on it.

From the above, we can infer that the temperature of the chimney will be within the range of ideal values if the computation is done correctly. The section of the chimney that does not match the power of the gas boiler is clearly indicated if the temperature is too high and needs to be lowered. It is advised to re-translate the smoke system while keeping in mind the normative values in order to lower the temperature of the outlet gases.

Video: condensate in a chimney

Selecting the appropriate chimney for your gas boiler is essential for both efficiency and safety. There are a few different kinds of chimneys to take into account, such as masonry, metal, and plastic. Every type has advantages and disadvantages, so it’s critical to choose the one that best fits your requirements and price range.

To guarantee adequate ventilation and effective removal of combustion gases, the diameter and height of a chimney must be precisely calculated prior to installation. These specs are determined by a number of factors, including fuel type, boiler size, and local building codes. It is strongly advised that you seek professional advice to guarantee safety and compliance.

A chimney for a gas boiler usually needs to be installed in a few steps. To ensure correct venting and prevent downdrafts, the chimney must first be extended above the roofline and firmly fastened to the boiler. It is essential to seal all joints and crevices to stop leaks that can reduce the system’s effectiveness.

For the chimney to continue operating safely, regular upkeep and inspection are necessary. This entails clearing out any soot or debris accumulation, examining joints and seals, and looking for obstructions. You can extend the life of your gas boiler and increase its efficiency by maintaining a clean chimney.

Video on the topic

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Alexandra Fedorova

Journalist, author of articles on construction and repair. I will help you understand the complex issues related to the choice and installation of the roof.

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