What pipe to choose for the chimney: regulatory guidelines and rules
Installation of a stove or fireplace involves the installation of a smoke removal system. In this matter it is not enough to choose the right pipes for the chimney, it is also necessary to observe a lot of construction and fire prevention rules. Otherwise, the operation of heating equipment will be ineffective and unsafe.
Errors made during installation of the chimney not only reduce the return on the operation of the firebox, but can also lead to tragedy.
Regulatory requirements for the installation of chimneys
The main and only purpose of the chimney is the removal of exhaust gases from the heating boiler into the atmosphere outside the building where the stove, boiler or fireplace is installed. At the same time, the efficiency of the heat-generating equipment directly depends on its proper installation.
You can put in the house a boiler with excellent efficiency, but to prevent miscalculations when installing the chimney.As a result, excessive fuel consumption and lack of comfortable air temperatures in the rooms. The chimney must be properly selected section, location, configuration and height.
If there are two boilers in the house or a stove and a fireplace in different rooms, then it is better to make separate pipes for each of them. The version with one chimney is allowed by SNiPs, but only a professional stove can correctly calculate it.
The diameter of the chimney is selected depending on the used heating equipment. When installing the boiler, it is already set by the manufacturer by the branch pipe. It is forbidden to connect pipes of smaller section to it, and more is simply not necessary. In the second case, to increase the thrust will have to mount the gearbox, which costs a lot of money.
In the case of a stove, fireplace or Russian brick stove, everything is somewhat more complicated. It will have to do engineering calculations taking into account the fuel used and the size of the furnace. It is much easier to take the finished project of a similar furnace, time-tested. Fortunately, there are many options with a well-defined order of brickwork.
The higher and longer the chimney, the stronger the thrust. However, this can lead to overheating and destruction of its walls. Plus, a strong increase in thrust is a prerequisite for the emergence of turbulence in the chimney, which is accompanied by hum and low-frequency noise.
With a pipe too low, the ridge can become an insurmountable obstacle to the smoke coming out of it. As a result, there will be a reverse thrust effect with the overturning of flue gases back into the furnace.
During normal operation of the chimney, horizontal wind flow, turning over the pipe section above the roof, turns upwards. The result is that discharged air is formed above it, which literally “sucks” smoke from the outlet.However, this process can be hampered by the ridge roof ridge and even a tall tree in close proximity to the house.
General requirements for the installation of smoke exhaust systems
Building codes require chimney to do as follows:
- Its length from the grate to the top point should be from 5 meters (the exception is possible only for buildings without attics and only in conditions of stable forced traction).
- Taking into account all possible bends, a height of 5–6 m is considered optimal.
- The distance from the metal chimney to the structures of combustible building materials should be from a meter.
- The horizontal tap immediately behind the boiler should not exceed 1 m.
- With the passage of roofing, walls and ceilings inside the house should be equipped with a channel of non-combustible materials.
- To connect the metal elements of the pipe sealant should be used exclusively heat-resistant with a working temperature of 10000FROM.
- Above the flat roof chimney should rise at least 50 cm.
- If a non-brick chimney is constructed above the roof level by 1.5 meters or more, then it must be strengthened with the help of stretch marks and braces.
Any slopes and horizontal sections inevitably reduce the draft in the chimney pipe.If you do not make it straight, then the bends and displacements are best performed from several inclined segments at a total angle of up to 45 degrees.
When constructing ventilation and chimney shafts in parallel in the same construction above the roof, in no case should they be covered with a common cap. The outlet from the furnace must necessarily rise above the ventilation pipe, otherwise the draft will decrease and the smoke will begin to suck back into the house. The same applies to the individual, but nearby located hoods and chimneys.
The choice of chimney material
The laying of the chimney in a private residential building can be done in several ways:
- With a passage through the attic and roof.
- With the conclusion of the external walls and exclusively inside the building.
- With the passage only through the roof, bypassing the interfloor overlappings.
- With a support directly on a copper or the furnace or with fastening to walls.
- With offset vertical axis and in a strictly straightforward design.
The choice of the final configuration depends on the layout of the living rooms, the location of the heating unit, as well as the individual features of the structure and architecture of the cottage. In each case, it is recommended to select your own version of the chimney. It remains only to figure out which pipe to choose for the chimney, which material is best suited for this.
You can make a chimney out of:
- iron or asbestos pipes;
- heat resistant glass.
The section can be either round, square or rectangular. And the first of them is the most optimal. Of all the materials for self-assembly only with heat-resistant glass problems may arise. Its installation will require a device of a special supporting structure, competently and with a guarantee that only a specialist can assemble.
Option # 1: Traditional brick
Chimneys of baked bricks are made not for the first century. These are traditional and well-studied structures for the discharge of smoke gases by professional stove-makers.But they have to be done simultaneously with the construction of the dwelling; for heavy brickwork it is necessary to pour a separate foundation.
Among the advantages of a brick pipe are high fire safety, an attractive appearance, a well-studied design and additional heat transfer from the masonry. And among the shortcomings - the high cost of the work, a lot of weight and the need for the device of the foundation, as well as the strong roughness of the walls.
In general, brickwork is a reliable and efficient way of organizing a chimney. And the existing drawbacks can be easily circumvented by a banal installation inside a stainless steel pipe shaft. The steel liner will prevent clogging with soot and will take over part of the heat load, thereby protecting the brick and extending its service life.
Brick chimneys are constructed primarily by using solid fuels. They are satisfied with mounted ones, i.e. installed on the floor of the stove, rooted in the form of a separately constructed vertical outlet, and wall-mounted - located inside the bearing wall.When using a metal liner with a round cross-section, inserted inside a brick chimney, it can serve as a chimney of gas heating and cooking units.
Option # 2: Galvanized and stainless steel
Galvanization and stainless steel are resistant to corrosion and corrosive environment resulting from the combination of condensate and furnace gases. They are lightweight and do not need an additional foundation; for mounting, reliable fasteners to the wall will suffice.
On sale chimney steel can be found:
- Single wall - without insulation material.
- Double-walled sandwiches with insulation between steel walls.
When installing a steel chimney outside the facade, it must be insulated, otherwise heat loss and abundant condensate will negate all the advantages of this option.Thermal insulation is used on chimney sections extending beyond the roof and passing through an unheated attic.
At the cost of components, a chimney made of stainless or galvanized steel will be cheaper than brick and ceramic counterparts.
The chimney channel is collected from:
- rain cap;
- inserts with inspection hatches;
- straight pipes;
- condensate collectors.
All this should just be mounted together by inserting one section into another and missed the joints with a heat-resistant sealant. Such chimneys are suitable for almost all types of furnaces and fuel. Galvanized and stainless steel withstand high temperatures and soot effects for decades without problems.
Smooth surface of steel walls optimizes the removal of combustion products, eliminates the accumulation of soot. Exhaust pipes made of steel pipes are suitable for gas, liquid and solid fuel stoves. Metal modules are used for the construction of a chimney fully or partially with its connection to the brick channel or installation in the form of an insert.
Option # 3: Cheap Asbestos Cement
Pipes made of natural asbestos with cement as a bonding material began to be widely used in our country during the Soviet era. They were cheap, durable and produced in large quantities. They were mainly used in agriculture for land reclamation.
Initially, asbestos-cement pipes were not intended for the installation of chimneys. They are too fragile for this and do not tolerate high temperatures. However, the issue of price in many cases plays an important role. If there is cheap material on hand, then it must be used, leveling the problem areas in one way or another.
Asbestos pipes have another problem - the roughness of the walls from the inside.Gradually, they accumulate soot, which can ignite and simply explode. Plus, with continuous formation of condensate from a mixture of vapors and oxides of combustion inside the asbestos cement begins to break down.
This material is cheap, but using it for arranging chimneys involves a great risk. Such pipes should be cleaned more often. However, it is impossible to make a revision hole in them, it will have to be provided in the area from the furnace to asbestos cement.
Smoke ducts of asbestos-cement pipes are carried out mainly in the mounted version. The priority is the simplest scheme of the device and the vertical arrangement of all elements. If necessary, to make a bias apply nozzles of non-combustible materials.
Option # 4: Exotic ceramics and concrete
Ceramic chimneys have unsurpassed durability and high price. They are not afraid of overheating, aggressiveness of soot and corrosion. These pipes have very smooth walls, soot on which does not even linger.
When installing pipes made of ceramics are assembled the same as steel. Only around them is formed a box of expanded clay. Such chimneys practically do not heat up.Even that small part of the heat that is given by inert ceramics is absorbed by expanded clay concrete walls. The fire in the house due to the burning of such a chimney is nonsense.
The chimney construction of ceramics and expanded clay concrete weighs much less than brickwork of a similar purpose. But even in this case, it is necessary to make a separate small foundation for it.
An even more massive monolithic foundation will have to be made for a concrete chimney. This variant of smoke discharge is rarely used precisely because of the complexity and laboriousness of manufacturing the structure. It will be necessary to install the formwork, and after waiting for the concrete solution to solidify.
Typical mistakes beginners and self-taught
In the first place among the misstep - the wrong height of the chimney.Too high an option creates excessive craving for the likelihood of tipping over, pulling smoke back into the firebox and the room with the stove. 5–6 meters are considered optimal, but much depends on the size of the combustion chamber and the configuration of the chimney.
It is not allowed to overcool the chimney and to overheat it too much as a result of intensive burning of fuel in the firebox. Everything should be in moderation, otherwise the pipe may crack. To facilitate the identification of these cracks, you should whitewash the chimney section in the attic. On a white background, all soot soils will be noticeable.
Often, beginners when installing a steel chimney forget to ensure the removal of condensate. To do this, you need to make a special collection and insert hatches for revision into the pipe. Errors are made in the choice of steel grade.
With the usual burning of wood, gas or coal in a fireplace or heating boiler, the chimney heats up to 500–6000C. However, the temperature of the smoke, albeit briefly, can rise to 10000FROM.At the same time after a few meters from the furnace, they cool down to 200-300 degrees and do not pose a threat to the pipe.
But its initial meter section from the boiler has time to heat up very strongly. Steel must be heat resistant and able to withstand these loads. And the steel pipe should be insulated only a couple of meters from the firebox to prevent overheating of this chimney segment.
When laying bricks by an inexperienced craftsman, it is often allowed to shift their rows vertically relative to each other. When erecting walls, this is permitted, but in the case of the chimney it is absolutely unacceptable. This greatly reduces the efficiency of the chimney channel, as it begins to form turbulence and soot precipitation on the walls.
The foundation under the brick chimney must be super-reliable, otherwise the pipe may be moved to the side with its subsequent partial or complete destruction.And if the smoke is diverted to a gas boiler, then it is better to exclude a brick. It quickly collapses under the influence of the alkaline environment formed during the combustion of natural gas.
Conclusions and useful video on the topic
What mistakes are most often made when installing furnaces and chimneys to them:
How to put brick chimney pipes:
How to make a stainless steel chimney:
Reliable chimney pipes can be made of various building materials. The choice of options is quite extensive. The easiest way to do the chimney out of steel, and cheaper than brick. But if you need the most durable and safe removal of furnace fumes, then the undisputed leader is ceramics. It is expensive, but will last more than one decade. The main thing when installing all the options to comply with construction and fire regulations.