Solid fuel boilers are presented in different types and each of them requires its own type of chimney. We analyze all aspects of choosing a chimney for a particular boiler. Modern chimney for a solid fuel boiler long burning may be:
The height and width of each hole must not be less than the maximum horizontal section of the chimney. All heating devices and especially open fires require air for efficient and safe operation. Ensure that the room where the appliance or fire is located has an adequate continuous supply of air as required by the appliance manufacturer and building codes. Typically, the same ventilation size is used for space heaters or stoves, but always refers to OEM recommendations and building codes.
The device and requirements for the chimney
Despite the material from which you can make a chimney with your own hands, the device should always include:
As for the requirements, their list is as follows:
- The chimney must correspond to the characteristics of a long-burning boiler, that is, designed for:
a) a certain temperature of carbon monoxide;
This is important as an air starvation will lead to poor combustion and create bottom sediment-like problems and spillage of fumes and vapors back into the room, which can be unpleasant and dangerous. Old chimneys are often very efficient and, especially if unlined, combustion products and tar can be passed through the chimney walls. It is common knowledge that old chimneys are in poor condition due to the fact that flue surfaces and mortars are eaten away by corrosive condensates and soot deposits.
The chimney size can also be too large to meet the performance requirements of many modern heaters. Therefore, it is very wise to have any old chimney you use checked for its condition, and especially if you are planning to reopen an old chimney after many years of use. The inspection is best done by a chimney technician and begins with the chimney removed to ensure there are no obstructions such as broken brickwork or bird nests.
b) the amount of condensate formed during the combustion of wood, coal or pellet-type fuel;
c) a certain amount of sulfur compounds.
- Complete tightness.
- Smoothness of the inner surface of the chimney.
- Verticality and straightness of channels.
- Uniform duct cross-sectional area anywhere in the flue gas outlet.
- Mandatory insulation of those parts of the pipes that come into contact with cold air.
- The presence of a damper, if the boiler is not equipped with it, or an automatic draft limiter.
Features of a brick chimney
This type is the cheapest among all chimneys. It is a ceramic brick construction. Thanks to this material, the chimney can easily withstand carbon monoxide gases heated to high temperatures.
A smoke test should then be carried out to determine if there is any serious malfunction that could cause combustion products to escape through the walls of the chimney. The smoke test procedure is provided later in this manual. You should also check general state chimney in terms of structural stability, and make sure it is wind and water.
Performing these checks should identify repairs that are necessary, and more often, also require that the chimney be fitted with a new liner, which should improve performance and safety. There are many factory refining systems and it is important to make sure the correct chimney size is set for the application or fire that will be used. Many of the same installation points apply as for new chimneys.
But in the case of leaving the boiler and raising relatively cold gases upward (temperature 100-130 ° C),. This is bad because water begins to come into contact with carbon monoxide such as sulfur. As a result, sulfuric acid appears, which easily corrodes the walls of the chimney. The effect of such acid is evidenced by dark spots that have appeared on the outer surface of the chimney, near which there may be an exhaust pipe.
Made from clay, ceramic or refractory concrete, consisting of pumice or kiln-burnt aggregate, bonded with high alumina cement. These liners simply lower the chimney on the guide ropes using alignment strips at the joints. The gap between the liners and the chimney is then filled with insulating lightweight concrete. Although this type of liner provides a long service life, the existing chimney opening must be large enough to accommodate the liners.
Prefabricated bends are available on most systems. Not to be confused with single layer gas-only liners. These multi-strand flexible liners are factory made from two overlapping high quality stainless steel strips to ensure a smooth, sealed gasket. They simply drop or pull the chimney and can move along most bends. While their slim profile allows for quick installation in chimneys where other systems may not fit. their life can be reduced if abnormally high corrosive soots or condensation deposits are created and allowed to accumulate in the chimney.
Smoke comes out of many modern boilers not very hot. Especially this applies to pyrolysis, pellet and other long burning boilers... For this reason, if you want to build a brick chimney, then it is better to insert a metal or ceramic pipe in the middle of it. If carbon monoxide is heated to a high temperature, such a pipe is not needed in the circuit.
Avoid burning solid fuels with insufficient air supply, especially on stoves or closed appliances. Low flue gas temperatures will cause condensation and greatly increase the risk of excessive tar content and corrosive soot deposits. This is a common problem, especially when burning damp wood or coal, and should be avoided. If soot and condensation deposits can accumulate in the chimney, the deposits can ignite, creating a smoke fire that can damage the chimney and the appliance.
Another feature of such a chimney is the presence of rough walls. This means that the soot clings to them more easily. Cleaning also becomes more difficult. The inner duct is rectangular or square, which creates not very good draft.
Brick chimney construction
They build such a chimney with their own hands in the following sequence:
These deposits can also be very corrosive and, if not removed regularly, can corrode metal parts in both the chimney and household appliances. Always use the right solid fuel... There are some processed fuels, such as crude petrocoke, which can cause spitting when booming and also produce abnormally high temperatures along with highly corrosive deposits. Therefore, it is recommended that you seek advice from approved charcoal sellers.
How to make a chimney for a solid fuel boiler efficient
Never incinerate household waste, plastics or chemicals that can generate harmful vapors and corrosive vapors, as this can be hazardous to health and cause premature corrosion of metals. If wood is used as fuel, it is important to make sure it is dry and well seasoned. This means that the wood has been cut into logs, then split and laid outdoors under a waterproof cover that is open on all sides to allow free air flow for natural drying.
- Pour the foundation... The brick structure is heavy and therefore needs a solid support. If the boiler is to be located on the second floor of a house or higher, then the base for the chimney must be a solid reinforced concrete floor. It is better to make the chimney in the middle of the inner load-bearing wall or next to it.
- Lay out the first continuous row... A metal sheet and a door are placed on it. For masonry, it is correct to use solid ceramic bricks. The mortar is ordinary masonry.
- Lay the rest of the chimney... In this case, the masonry must be made airtight. The thickness of any wall must be at least half the length of the brick. As for the dimensions of the channel, they must be multiples of the length of the brick: 1 / 2x1 / 2, 1 / 2x3 / 4 or 1 / 2x1 brick. At this stage, a door is also built in opposite the place where a horizontal pipe extending from a long-burning boiler enters the chimney.
- If carbon monoxide gases released from the pellet or pyrolysis boiler will rise up the chimney, then it is better in the middle.
- Chimney sections in the attic and above the roof are insulated with mineral or basalt wool.
- An aerodynamic hood is placed at the top.
Most wood needs to be aged for one or two years, depending on the moisture content. Bringing the log home a few days before burning will help reduce moisture content and increase productivity. To start with all the passes, it is necessary to check the number of deposits created monthly. The frequency of sweeping required to prevent rainfall can then be determined. As a guide, all chimneys should be flushed before and during the heating season, and ideally at the end of the heating season, to prevent the deposition of tar and soot, which are corrosive to the chimney and appliance during the sleeping period.
It is worth saying that such a chimney is only a vertical structure. The horizontal pipe that connects it to the boiler must be made of stainless steel.
Ceramic chimney
Its features are as follows:
- Very good resistance to high temperature and any aggressive chemical compound generated by burning wood, coal or pellet-type fuel.
- The longest shelf life among all types of chimneys.
- Smooth walls.
- Round cross-sectional shape.
- Requires external ventilation due to its ability to absorb moisture.
- Convenient cleaning.
It is not recommended that the appliance is excessively red and smoke fires started by trying to decan the chimney. Soot and tar deposits will be significantly increased if non-seasonal wood is burned, which can lead to chimney fires. If a chimney fire breaks out, it is advisable that your chimney device and appliances be checked for damage before reusing the fire or heater.
Refractory brick chimney
It is also recommended to check at least every year or two the exposed chimney parts, gaskets and terminals for signs of damage. Just like outside the home, chimneys can suffer wear and tear from extreme weathering. If at any time smoke or vapors are detected or suspected from the appliance, chimney or liner, seek immediate advice from an installer or fuel specialist if there is a blockage or failure. Do not use a fire apparatus or chimney until it has been thoroughly checked for safety and reliability.
Its scheme is represented by the following elements:
- Ceramic pipe. For other types of long-burning solid fuel boilers, it is correct to use a ceramic pipe that can withstand 600-650 ° C.
- Insulation.
- A shell of block modules. They have ventilation ducts and holes for reinforcement.
- Fittings.
The device of a chimney for a solid fuel boiler is carried out in almost the same sequence as the creation of a brick chimney. That is, the common things are pouring the foundation, embedding cleaning doors and placing the aerodynamic hood. 
Vapors can be hazardous. Power sweeping with a brush and rods is the only cleaning method recommended by British standards, as materials other than soot can block passages such as mortar, brickwork, bird nests, etc.
For this reason, chimney cleaning using only chemical chimney cleaners or vacuum cleaning is not recommended as an alternative for proper chimney cleaning. Sweeping brushes should be made of suitable bristles and have the same diameter or area as the deflection and be fitted with a ball or freewheel at the end to prevent chimney walls from scraping, especially in bends. Many chimney manufacturers make recommendations on the types of brushes according to their systems.
Instead of laying bricks, concrete blocks are laid. This process is easier because the blocks are simply stacked on top of each other. After laying 2-3 blocks, a mineral wool insulation and a ceramic pipe are placed inside. Usually a pipe with a length of 0.6-1 m is used. Reinforcement must be inserted into the holes at the corners of the blocks.
To make the connection of two ceramic pipes reliable and tight, acid-resistant mastic is used. She lubricates a special groove located at the top of the pipe. Fittings are located at the ends of the pipes. They improve the bond strength. A special tee is used to connect the horizontal pipe from the boiler.
If there are doubts about the condition of the chimney, or the old chimney must be put into operation after a long period of non-use, it is advisable to check it for smoke. The purpose of the smoke test is to detect if there are any serious defects that could cause smoke to leak through the walls of the chimney during normal operation.
There is a different smoke removal procedure for gas fires. It is also recommended that this smoke test be carried out during the construction of traditional masonry and upon completion of all smoke installations. It should be remembered that the purpose of the smoke test is to identify and correct any malfunctions that may cause fumes during normal operation of the appliance and flue. By closing the bottom and the top of the chimney during the test, the smoke generated by the pellet together with normal barometric conditions creates a positive pressure that would not be generated in the normal use of an installation that operates at negative pressure, i.e. sucking in air and drawing combustion products into the chimney ...
Steel chimney
It is of two types:
- Single wall
- Double-walled (known as).
In both cases, it is used steel with a thickness of 1 mm... To carry out the installation of a single-wall chimney correctly, it is necessary to make a reinforcing structure in the form of concrete blocks and insulation. In fact, in order to build it yourself, you need to repeat the procedure for building a ceramic chimney. Only according to the scheme, instead of a ceramic pipe, it is necessary to take a steel pipe. You can build a brick structure and insert a pipe into it.
Thus, the pressure generated during the procedure is more than capable of creating a small smoke leak from any joints in traditionally masonry or the joint between prefabricated metal chimneys and chimneys... The small leak detected during this test will therefore not be a major risk when the unit is used under normal operating conditions, since a leak point does not indicate a malfunction that could worsen. However, if there is a significant or intense smoke leak, the cause must be investigated and corrected.
Immediately after installing the solid fuel boiler, you should begin to create a system for the emission of gas and smoke. This work can be entrusted to hired craftsmen, but it will cost money. Self-assembly will allow not only to save money, but also to fully understand the structure of the chimney, which is useful for its further operation and maintenance.
The device and requirements for the chimney
Defective components, improper installation and incomplete connection of smoke gaskets are the most common problems that cause serious leakage and require corrective action. Longer warm-up times with a wet or cold flue may be required. If there is no grate on the grate or fire box, use a blowing lamp for 10 minutes or more to install the chimney hood. It should be understood that none of these methods produce the same temperatures or volumes of hot gases that are typically generated during use of the instrument.
To order or make a chimney for a solid fuel boiler with your own hands - which is more profitable?
The answer to this question is not as obvious as it seems. By design solid fuel boilers are similar to conventional stoves. And it may seem that the chimney device for him is simple task... Do not succumb to this delusion. For high-quality removal of combustion products, a well-thought-out, durable and reliable design is required. Neglect of these rules is unacceptable, because the lives of people living in the room depend on it. Loose joining of materials or design errors lead to the penetration of carbon monoxide, hazardous to health.
Therefore, in the absence of furnace installation skills, it is wiser to entrust such a responsible job to a professional. If you have experience and self-confidence, you can do the installation yourself. However, it is better to order the calculation of chimneys for a solid fuel boiler from a specialized organization.
Regardless of the material used for installation, all chimneys for solid fuel boilers are structurally similar. The smoke exhaust system consists of the same functional components:
- Chimney. Cylindrical or rectangular section through which combustion products are removed from the boiler. Must be made of durable and heat-resistant material.
- Condensate collector. Everyone remembers from the physics course that when heated air comes into contact with a cold surface, condensation forms on it - small accumulations of moisture. To prevent water droplets from flowing into the boiler, the chimney must be equipped with a means to remove them from the system. The condensate collector is equipped in its lower part, which does not come into direct contact with the boiler, but is connected through a tee.
- Gate - a damper for stopping the air supply to the system from the boiler. The gate is necessary for economical operation - so that after stopping the operation of the boiler, the exit of warm air to the external environment is blocked.
This is a typical flue gas system. When working with specific materials, it may have slight differences and additions. For example, steel chimneys are equipped with a linear deformation compensator. He is responsible for the tightness and reliability of the system, because constant heating and cooling cycles lead to loosening of the chimney. This reduces the tightness of the docking of the components.
Installation rules
- Fire safety should be the most important guideline for the construction of a chimney structure for a solid fuel boiler. The distance from the walls of the chimney to other surfaces should be at least 38 cm. When building an internal chimney, it is necessary to very carefully isolate the places in which it passes through the ceilings.
- The walls should not be narrower than 10 cm, including insulation.
- The height directly affects the efficiency of flue gas removal and the draft force in the chimney system. It is necessary that the upper point of the chimney is at a distance of at least one meter relative to the roof.
- Accurate calculation of the internal cross-sectional area. It is necessary that this value remains constant throughout the chimney in order to avoid a decrease in efficiency.
- The maximum length of horizontal sections in the system is 1 m.
- The design must have a condensate collector and service doors.
Before proceeding with the construction of the chimney, we recommend that you thoroughly study the operating instructions supplied with the boiler. This document contains strict requirements for what parameters a chimney should have, ideally suited for a given boiler model. In the absence of such information (or with complete confidence in your skills), you can build it, choosing the material at your discretion. Key requirements that cannot be ignored:
- For efficient gas evacuation, the chimney must have the most vertical design.
- The cross-sectional areas of the pipe and the boiler outlet must be at least equal, and it is better if the first is larger than the second.
- A deflector (head) is required.
- If the roof material is flammable, the system must be equipped with a spark arrester without fail.
- The deflector must be installed in the area of the wind support.
How to determine the zone of wind support? Find the highest point of the nearest obstruction that changes the direction of the air masses. It can be a tree, a neighboring building, or a roof ridge. From this point it is necessary to draw a straight line to the chimney at an angle of 45˚. Everything that is under it will enter the space of the wind support. At a certain wind direction, the air from this zone disturbs the draft, increases it (fuel consumption increases, the boiler efficiency decreases), or even reverses it.
The chimney is assembled very simply by alternately inserting its elements into each other. But this installation is divided into two ways:
- Condensation. The components are connected taking into account the direction of the condensate drain. This is necessary in a system that does not have a vapor collector.
- Through the smoke. The parts of the structure are connected according to where the gas is moving.
In systems with a condensate collector, part of the structure is assembled according to the first principle, and the rest according to the second.
It is known that the intensity of the removal and discharge of heated smoke and gas into the external environment is directly influenced by the thrust. This is a key characteristic of a chimney system, demonstrating its efficiency. The cross-section of the chimney, diameter and height affects the thrust force:
- the narrower the upper part, the sooner the gas-smoke mass comes out;
- To speed up draft helps to minimize inclined or horizontal parts and branches, that is, creating as vertical a chimney as possible.
Determination of efficiency
The reason for the low efficiency is the incorrect assembly of the system, poor docking of components. In most cases, these errors are noticeable at the time of assembly, so they can be easily eliminated. Otherwise, to eliminate the shortcomings, you have to dismantle and assemble the chimney again.
A sign of high efficiency is a noticeable hum in the pipes that accompanies the operation of the boiler. The smoke extraction rate is regulated by means of a gate partially covering the chimney.
Chimney types
The classic version, which has been used since ancient times and has retained its relevance today. It makes sense to build a brick chimney only for a boiler with a high efficiency. A significant part of the energy is spent on heating thick material walls. A system built on a boiler with a weak efficiency, in this case, will have very poor gas removal.
Advantages:
- The brick is heat-resistant, it withstands the passage of combustion products heated to + 900˚C.
Disadvantages:
- Destructibility. The accumulation of soot and the deposition of condensate on the walls of the chimney leads to the fact that the brick is cracked and chipped. To solve this problem, a steel pipe is inserted into the brick pipe.
For the reliable construction of such a chimney, you need to clearly understand the essence of the processes and understand the brick laying scheme. The pipe must be bandaged, in strict accordance with the masonry scheme. This part in height should not rise above the upper edge of the 5-7th row of bricks.
Then you need to make a fluff. This means that the outer perimeter of the chimney increases, while the inner remains the same. The fluff is very important, because the thermal insulation of the system is provided, that is, it directly affects the efficiency. How many rows of bricks are laid in the area of the fluff is dictated by the thickness of the overlap between the floors. However, after climbing to the upper floor, you need to raise the fluff at least 1-2 rows relative to the floor.
Then a riser is constructed. It is led through the last floor, after which it increases by 0.5 bricks as it approaches the roof. This part of the system is called the otter. It is the widest and is built from 8-9 rows. The otter is needed to thermally insulate the smoke exhaust channel and prevent debris or weather from entering the room. The final step in building an otter is to create a gentle slope of cement that goes into a pipe neck. The dimensions of the neck and the riser are the same.
The neck is laid from 6-7 rows of bricks, and after it a head is built from 2-3 rows. A hood should be placed over the chimney to protect it from rain, snow and debris. For a detailed examination of the procedure for erecting a brick chimney, we recommend watching the video.
These chimneys are made of ordinary steel or stainless steel. Due to the longer service life, the second option is much more in demand. Constructions made of ordinary steel usually last from 3 to 5 years.
Material advantages:
- Heat resistance. The steel is resistant to hot smoke and gas masses (up to 700˚C).
- Resistant to moisture. This means that condensation does not affect the durability and reliability of the system.
- Affordable price.
Unlike chimneys made of glass or brick, steel ones can be supplemented with some details during operation. For the installation of the smoke exhaust system, stainless steel grades 321, 316 and 316L are suitable.
A good, but not the most profitable material for the construction of a chimney. It is becoming more and more popular, especially in the installation of external smoke exhaust systems. Has pluses, but, of course, is not devoid of disadvantages.
Material advantages:
- panels are equipped with a heat-resistant layer and heat-insulating material at the production stage;
- the design is compact and easy to assemble;
- the operation of these pipes is not accompanied by the formation of condensate;
- a smooth inner surface creates turbulence, which accelerates the removal of smoke and gas, and also prevents soot from settling on the walls;
- the material is fireproof.
Disadvantages:
- a chimney made of sandwich panels is much more expensive than analogues;
- the service life of the structure is, on average, 10-15 years;
- gradually the joints become less dense.
Counts the best choice to create safe, durable and reliable chimneys for solid fuel boilers. Includes three layers:
- inner - ceramic tube;
- middle - insulating layer of non-flammable mineral wool;
- external - a frame made of refractory bricks.
- resistance to gas-flue flow with temperatures up to + 900˚C;
- the mirror surface of the inner walls does not accumulate soot;
- no condensation forms on the walls;
- the material does not rust when exposed to moisture;
- a ceramic chimney is suitable for boilers operating on any fuel;
- installation is easy and fast;
- the structural components have few seams, which ensures high tightness even after long-term operation;
- ceramic chimneys last at least 30 years.
Chimneys made of this type of material have only recently appeared on the Russian market and have not yet had time to gain popularity or wide recognition. Among the advantages of the material are durability, strength, heat resistance and special appearance... The only but very noticeable disadvantage is the very high cost.
