Experienced craftsmen know that it is not enough to fold the stove well - it is equally important to build a chimney that can provide good draft. For a number of reasons, the chimney may not work efficiently enough, and the acceptable initial characteristics begin to decline over time. It is not difficult to prevent such troubles - it is enough to equip the chimney with a deflector. This simple device will not only improve its aerodynamic properties, but also protect the smoke channel from debris and precipitation.
Probably, there is no such person who would not notice the bizarre hoods installed on the tops of chimneys and ventilation ducts. If you conduct a survey of what such devices are for, then the majority will answer that a deflector or chimney (as the stove-makers call it) is needed so that dirt and moisture do not get into the chimney. Of course, there will be more knowledgeable people who will say that a simple metal superstructure also serves to increase traction. And only a few will be able to explain how this happens.
The deflector installed on the chimney has been seen by many, but only a few know its structure and principle of operation.
At the same time, everything is simple. Most often, a decrease in thrust and a deterioration in the thermal efficiency of the furnace appears against the background of sudden changes in atmospheric pressure or with strong winds. Unfavorable weather conditions often even lead to reverse draft, causing smoke to form in the premises. And this is where the deflector comes to the rescue. Translated from English "deflector" is nothing more than a deflecting device or a reflector - these words perfectly characterize the principle of operation of a simple structure.
Installed in the path of the wind, the deflector forces the air flow around it around the periphery, contributing to the appearance of high and low pressure zones. If you remember the school physics course, you can remember Bernoulli's law - most modern traction amplifiers work according to the same principle. A thin atmosphere on the leeward side of the deflector creates an additional pressure drop between the blower and the upper cut of the chimney... As a result, the smoke is, as it were, forcibly "sucked" from the chimney, thereby increasing the flow of air into the combustion zone.
The principle of operation of the traction amplifier is based on Bernoulli's law
The topic of chimney reflectors has recently been widely discussed in scientific circles, as a result of which many interesting designs have appeared. According to the studies carried out, some of them can increase the efficiency of a heating device by 20%. For this reason, the selection and calculation of the reflector is one of the most important stages in the design of direct combustion furnaces.
In its simplest form, a chimney reflector consists of several parts:
In addition, the chimney is equipped with brackets that are used to connect its individual parts to each other, and some structures are also equipped with annular rebounds, which effectively protect the structure from precipitation.
The chimney reflector has a simple design, so it is easy to make it yourself
As mentioned above, at the end of the 20th century, many reflectors were developed, which differ in both configuration and aerodynamic characteristics. Let's talk about the most popular designs in more detail.
The reflector, developed by specialists from the Zhukovsky Central Aerodynamic Institute, is perhaps the most famous and repeated development in our country. The design has an open flow path and is distinguished by excellent protection against wind blowing into the chimney. At the same time, these advantages in winter time turn into some disadvantages. So, at low temperatures, the diffuser can be covered with a layer of ice, which will reduce the already small gap between the inner cylinder and the bell. Since the minimum flow area interferes with the natural draft of the chimney, TsAGI deflectors are best used for tall buildings and on terrain with constant air flow.
Easy to manufacture, but quite effective, the TsAGI deflector is one of the most popular designs among home craftsmen
The design, which was proposed by the aircraft designer D.P. Grigorovich and the scientist A.F. Vol'pert, takes into account all the shortcomings of the TsAGI reflector. Using a tapering channel design in their development, the engineers were able to increase the gas flow rate so much that the reflector began to work perfectly even in the complete absence of wind. Such a chimney is a real salvation for chimneys, which are located in lowlands or are shaded by multi-storey buildings.
The Grigorovich reflector is an improved version of the TsAGI deflector
The deflector, whose shape resembles the letter "H", has several significant advantages. So, the horizontal part of the structure allows you to divide the flow of combustion products into two parts, which is important for furnaces with increased productivity. In addition, the cross member protects the vertical channel from the penetration of debris and precipitation - the structure does not require an umbrella. Despite their simple appearance, the H-shaped reflectors have two diffusers, which allows them to cope with even the most intense emissions from industrial furnaces.
Easy-to-manufacture H-shaped deflector is best suited for powerful heating units
Just like the TsAGI deflector, the disc-shaped reflector has an open flow path - this, in fact, determines its effectiveness. It is no coincidence that the chimney got such a remarkable name - its design consists of several cone-shaped caps (plates), in the center of which a flue hole is made. In this design, the hoods directed towards each other form a narrowing channel, in which a vacuum is generated as soon as the wind blows from some direction. Due to their open design, disc deflectors are often wrapped in a metal mesh. Thus, the flue is additionally protected from debris, and the environment is protected from flying sparks.
The disc deflector is one of the most unpretentious designs
This chimney is almost a complete analogue of the device developed by TsAGI. The improvement is at the top of the device - the engineers just turned the protective cap upside down and installed it just above the diffuser. This was enough to prevent the formation of ice, which interfered with the operation of the original device during severe frosts.
Outwardly, the Volper has the maximum resemblance to the TsAGI deflector, but is devoid of its inherent drawbacks
Being a symbiosis of a simple chimney and a weather vane, devices of this type have a rotary cap (curtain). Turning around its axis during gusts of wind, the vane protects the chimney from blowing out and contributes to the appearance of a low pressure zone on the leeward side. Often, the curtain of a swivel chimney is decorated with various figures, which makes the design with a weather vane extremely advantageous aesthetically.
The deflector with a vane has a rotation unit, thanks to which it always occupies an optimal position relative to the incoming air flows
The design is based on the simplest chimney, which consists of a diffuser and a hood. In order to prevent the emission of sparks, the space between the individual parts of the reflector is covered with a metal mesh. In principle, any open-type deflector (such as a poppet) can be made safer by installing a spark arrestor. For this reason, spark arrester deflectors are more of a series of devices than a separate design.
A deflector with a metal mesh will not only increase traction, but also protect property from fire
The reflector is installed at the very edge of the chimney, which makes maintenance and repair very problematic. For this reason, it is best to use weather-resistant materials for the manufacture of the device:
Whatever design you choose, the first step is to carry out the necessary calculations and make drawings and patterns. After that, a cardboard model of the reflector is constructed on a scale of 1: 1. After making sure of the correctness of their own research, they start cutting metal sheets. Such a scheme allows you to eliminate errors in time and make the design more attractive.
When choosing a deflector for self-production, we recommend not to spray on trifles and immediately proceed with the construction of an "adult" structure such as TsAGI or Grigorovich-Volpert. Well, those who have sufficient experience in handling locksmith tools can try to build a chimney with a weather vane. In addition to its direct responsibilities, the revolving structure will create an aura of individuality around the house and will serve as a source of pride for others.
When choosing a deflector, many points should be taken into account, starting with the design of the heater and ending with weather factors and terrain features. We offer you some simple advice on the selection of equipment from stove-makers with many years of experience:
The results of numerous experiments indicate that circular deflectors work much more efficiently than rectangular ones. The reasons for this behavior lie on the surface - a more optimal shape and the absence of corners makes them able to not depend on the direction of air flows. In order to install a round deflector on a rectangular chimney, a special adapter is used.
The adapter for installing a round deflector on a square chimney can be made of the same material as the reflector
When starting to manufacture a reflector for a chimney, you must have on hand:
As for the materials, their choice depends on the design. For the manufacture of static deflectors, only sheet metal will be needed, while rotating reflectors also need parts to make a rotation unit. In general, you will need an axle, bearings, fasteners, and a tapping tool.
Along with detailed diagrams and drawings of the TsAGI defect, the engineers of the research institute provided a calculation method for chimneys of any size.
TsAGI deflector circuit, allowing accurate calculation of its parameters
To determine the dimensions of all components, it is necessary to determine the inner section of the chimney. Further calculations are carried out on the basis of the optimal ratios that were obtained experimentally:
If the chimney is built from standard metal pipes, then there is no need to do calculations at all - you can use a special table. In other cases, the calculations should be approached with due attention, since incorrect geometric relationships will lead to a violation of the aerodynamic properties of the reflector.
|Furnace tube diameter, cm||Diameter of the outer casing, cm||Height of outer casing, cm||Diffuser outlet diameter, cm||Cap diameter, cm||Installation height of the outer casing, cm|
One should not think that the TsAGI deflector is a design intended exclusively for round chimneys. Using the above technique, you can also build a reflector for a brick chimney. And although its efficiency will be slightly lower than that of the original device, you will immediately notice an improvement in traction and an increase in the efficiency of the heater.
Geometrically, the diffuser of an oven reflector is a hollow cone with a truncated top. Its development is shown in the lower figure. We calculated all the required dimensions above, so making cardboard patterns is not difficult.
Pattern for making the diffuser body
With the manufacture of a pattern for a cap, the situation is even simpler - it is a circle with a radius of 1.7d / 2. To give it the shape of a cone, an angular sector with a width of 30 ° is cut out, leaving a 20 mm overlap to connect the parts of the cone to each other.
Pattern for making a cap
The outer casing of the diffuser has a cylindrical shape, so its prototyping is not difficult - just cut out a cardboard strip of the required width and roll it into a ring.
After gluing the model in full size, it is necessary to check how much its shape and dimensions correspond to the chosen design. If possible, you should make sure that the copy of the deflector is installed on the chimney as tightly as possible.
Having worked out the technology on a paper model, you can safely start making a metal deflector
After checking the calculations on a paper model, the necessary adjustments are made to the design and the construction of a metal reflector is started.
In the manufacture of the TsAGI deflector, the author of this article made one mistake, which subsequently required additional time and labor. Considering myself quite experienced in plumbing, I refused to make a paper model, considering it a childish undertaking and an unnecessary waste of time. The result of such negligence appeared after cutting out blanks from galvanized steel. All attempts to create volumetric details (diffuser, outer casing and umbrella) have failed for a completely banal reason.The fact is that I completely forgot about gaps, so the parts could only be joined butt-to-end. Although a solution was found in increasing the linear dimensions of the parts with metal stripes, the design still turned out to be not as neat as it was originally intended. So, friends, I advise you to listen to the recommendations of experienced craftsmen, and most importantly - do not forget about the slips!
It is necessary to follow a certain order of work, otherwise it will be very difficult to connect the individual parts of the deflector into a single structure.
Having rolled up a cylindrical part, it is necessary to fasten its edges with rivets
If there is no riveter at hand, then separate parts of the workpieces can be connected using threaded connections. In the case when the reflector is made of stainless or black steel, you can even use a welding machine.
When making a cap, it is necessary to check the flatness of its lower edge - for this, the part is laid on a flat surface
In order to reliably attach the umbrella to the deflector, three attachment points are enough
Before attaching to the diffuser, the mounts are bent at an angle of 90 degrees
The final assembly of the deflector is carried out using rivets.
Having finished with the manufacture of the chimney, they proceed to the last stage - the installation of the structure on the chimney. Those who think that it is easy and simple to do this will have to be a little disappointed - in fact, the installation of a reflector on a chimney is one of the most important and crucial moments.
Before installing the deflector, carefully inspect the chimney and the surrounding area. If there is access to the upper cut of the chimney, then the traction amplifier can be fixed in several ways:
In the first case, longitudinal grooves are cut on the inlet pipe - they will allow it to shrink, covering the chimney as tightly as possible. If bolts and nuts are used for fastening, then the structure is pushed onto the chimney and through holes are made from three sides. After installing the fasteners and tightening the nuts, any protective compound is applied to the open threaded part - the connection will need to be disassembled periodically.
To securely attach the deflector, you can use additional brackets - the main thing is that the structure cannot be ripped off during strong gusts of wind
When installing the deflector on the chimney, it is not recommended to use riveted joints. When the time comes to clean the chimney from soot, it will be problematic to remove the traction amplifier.
For high chimneys, as well as in the event that it is difficult or unsafe to get to the chimney, the reflector is attached to an adapter, which allows you to tightly fit the device without additional fasteners. In this case, the order of work looks like this:
Since in the latter case it becomes possible for air to be sucked into the gap between the coupling and the chimney, the gap should be caulked with any refractory material.
Considering the latter option not reliable enough, the author of these lines fixed the reflector with wire braces. For this, I had to use longer bolts at the point of attachment of the deflector with the coupling - I attached pieces of wire to the threaded part protruding outward. By the way, this method made it possible to use the most dense coupling and to do without additional sealing - the braces made it possible to install the structure on the chimney with a slight interference.
The variety of deflector designs makes it easy to find the right option. Spending a few hours on its manufacture and installation, you can significantly increase the draft and thereby increase the productivity and safety of the heater. It is only important to correctly calculate the parameters of the reflector and make it in full accordance with the drawings - only in this case the laws of aerodynamics will play into your hands.
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An important condition for the full functioning of the stove is a normal draft, which will help to remove the combustion products. This indicator is strongly influenced by the diameter of the chimney. If it is of a small cross-section, then the combustion products will not be able to go outside and will begin to accumulate inside the house. In the case of using a wide chimney, cold air flows will prevent burnt-out substances from rising. All these and other nuances can be compensated for with a traction amplifier, which can really be done independently.
First of all, the chimney is installed in order to increase traction by diverging air flows. There are several functions of the device:
For the reliable functionality of the device, it is necessary to take a responsible approach to the selection of material for direct production. Copper is one of the most popular materials because it is durable and aesthetically pleasing. If the cap for the chimney pipe is made of any other building material, then all mounting elements must be brass.
The weather vane looks spectacular on the chimney, made of stainless steel or galvanized. The most popular is the polymer-clad stainless steel device. The service life of such a device reaches 20 years. The polymer coating makes it possible to match the hood to match the roof.
Beautiful forged weather vane will become a real decoration of the roof
The type of weather vane is based on the structure of the pipe and the external shape.
Chimney with multi-slope hood
Vane for a brick chimney
Chimneys for a gas boiler in a private house. Selection rules and requirements for the installation of chimneys, their varieties and nuances of installation in a special publication.
When choosing a product, it is necessary to take into account the direct structure of the chimney. The ideal option is a three-layer device made of modular sandwich panels. With such a device, you don't have to worry about protecting the chimney from precipitation. Since, all the moisture that gets inside the structure is collected in the collector.
When it comes to gas devices, in this case, the nozzle is preferable. The best option for a solid fuel system is a vane deflector.
There are no contraindications for brick pipes in conjunction with a solid fuel system and you can give preference to any cap you like.
Chimney system installation diagram
To correctly make a cap on a chimney with your own hands, you should use drawings of simpler samples.
For work, the following devices and materials are required:
Galvanized steel swivel hoods
Algorithm of work execution:
Drawing of a dropper apron with markings
Apron design options
The most important step is drawing up a drawing. To do this, it is necessary to measure the inner diameter of the chimney and calculate the parameters of the product according to the table.
If the inner diameter of your chimney differs from the parameters given in the table, the calculations are performed as follows:
Both measurements and calculations should be as accurate as possible so that there are no difficulties in the installation of the structure and its subsequent operation. If the pipe has a square section, then the deflector must also be made square, although the angularity of the body slightly reduces the efficiency of the device.
If the design must have a reverse cone (Grigorovich deflector), the diameter of the protective umbrella is made 3-4 cm larger than the diameter of the cone. After assembling both elements, the cone is applied from the inside of the umbrella and circled around the perimeter with a marker. Then two cuts are made on the protruding part of the umbrella and the resulting strip is folded inward. In the same way, another 6-8 strips are made at an equal distance from each other, bend them inward and reliably fix the reverse cone without additional fasteners and welding.
Grigorovich deflector circuit
It is more convenient to attach the dome with a reverse cone to the diffuser with construction studs. To do this, before installing the cone on the umbrella, three holes are drilled in it around the circumference, the ends of the studs are inserted and the nuts are tightened. Then put on an umbrella on top, fix the cone in the way described above. In the upper part of the diffuser, from the outside, hinges made of tin or aluminum are riveted and the lower ends of the studs are inserted into them. This design withstands strong gusts of wind, serves for a long time and reliably.
In a similar way, you can assemble a deflector of any type, the main thing is to draw up the correct drawing. The only difference will be in the number and shape of the parts. The finished device only needs to be mounted on the chimney.
A turbo deflector for ventilation is used not only in apartments and private residential buildings, but in industrial, warehouse and agricultural buildings. In the latter, this device helps to remove gases and excess moisture. In industrial environments, deflectors significantly reduce energy costs. In swimming pools, sports complexes and municipal institutions, rotary deflectors are often installed. Garages and cellars are equipped with turbocharged models.
The advantages of these devices include:
The only drawback of this device is that in the absence of wind, the turbine will stop working. Firstly, this will lead to the fact that the deflector will not work at full strength, and secondly, in the cold season, the system will freeze and stop functioning.
It is optimal to install the deflector on the pipe before it is installed on the chimney or roof duct.This will facilitate a rather laborious process and make the work safer.
To install the deflector, you will need tools and materials:
An example of installation using a ready-made TsAGI deflector made of galvanized steel.
The device of the deflector is quite standard, each of its varieties consists of the following elements: special glasses, clamps for holding on the roof surface, as well as a branch pipe. In this case, the lower glass-cylinder has an even structure, and the outer one is expanded towards the bottom. They are put on top of each other, and a cover is installed at the top. The top of each cylinder is terminated with baffles in the form of rings that help to change the direction of the air flow.
The installation of rebounds is made in such a way that the external air flows suck through the free space between the rings and accelerate the removal of mining from the ventilation.
The turbo deflector has a rather complex design, so not many people undertake the manufacture of the device on their own. If, nevertheless, it was decided to perform just such a design, it is necessary to take care of the availability of the following tools and materials:
When self-manufacturing a TsAGI deflector, you will need: a mallet, a drill, a vice and metal scissors
When self-manufacturing, it is important to correctly complete the landing part, which will correspond to the desired pipe diameter. After that, plates are welded to the finished part with a tube located in the middle, into which the dynamic part of the device is inserted. Then, according to the finished template, blades of steel are formed, which are attached to the structure and form a turbo deflector. To understand the progress of the execution process, it is better to refer to the videos available on the web.
Most craftsmen prefer to make a TsAGI device at home, because making a deflector is quite simple. To do this, you need to take galvanized steel no thinner than 0.5 mm, from which the necessary parts are then cut out. Rivets, bolts and nuts are used to assemble the structure. To work, you will need the following tools:
After cutting out the necessary parts from sheets of tin, they are connected to each other using rivets
Due to the fact that a large number of ready-made drawings are available on the network, it will not be difficult for anyone to draw a diffuser. The main thing is to correctly determine the size. The most popular parameters are ventilation ducts with a diameter of 10-11 cm, especially if the hood is made of a plastic pipe.
So, after the necessary parts have been cut out of the sheets of tin, they are connected to each other by means of rivets. Then the finished deflector is put on the head, and the lower branch pipe is pulled together with a clamp. If the shaft is square, an adapter is additionally manufactured or purchased, the flange of which is fixed to the end of the pipe.
Properly designed ventilation will help maintain a normal microclimate in the house, and a deflector installed on the roof will provide traction, which quickly clears the room of exhaust air. Despite the fact that most of the models of devices are not distinguished by their high cost, they still guarantee a productive hood and preserve the health of residents.