Drawing of an exhaust hood for ventilation. What is a ventilation umbrella and why is it needed? Schemes and dimensions

A necessary element of any serious kitchen is an exhaust hood. Such a device is mandatory installed in industrial enterprises, but it also has a worthy place in household kitchens.

This extractor variant is exceptionally effective at removing cooking-related contaminants from the air. Let's take a look at the features of the operation of this exhaust equipment and the points that you need to pay attention to when choosing a hood for the kitchen.

A device of this type is a powerful hood designed for efficient air ventilation in the kitchen. They are most often installed directly above the cooking surfaces in restaurants, cafes, canteens and other catering establishments.

Such a device can be installed not only over conventional stoves, but also over other similar equipment: a grill, an oven, etc.

The quality of the dishes from the presence of a good hood will only benefit. Umbrellas trap water vapor, particles of oil and fat, remove odors from cooked dishes. All these contaminants rise up under the influence of hot air and enter the working cavity of the ventilation hood. Here, polluted air passes through the filtration system, where it is cleaned.

The exhaust hood is a stylish and modern device that will provide effective air purification in a domestic or industrial kitchen.

Then the air masses, freed from unnecessary inclusions, return to the kitchen or are removed through the ventilation duct, depending on the type of device.

Fatty contaminants move through a separate channel and are collected from storage cups, from which they are periodically removed.

Grease traps are special aluminum elements that are installed inside exhaust hoods. They trap particles of grease and other relatively large contaminants.

To facilitate the process of cleaning the drives from fat deposits, it is recommended to pre-fill the glasses with a special detergent that can effectively dissolve fat.

The advantages of exhaust structures such as "umbrella" include the following points:

the ability to use remote control;
high degree of automation;
the ability to install a suitable model in almost any area of \u200b\u200bthe kitchen;
a wide selection of various models made of various materials with an attractive design;
high level of performance.

Among the shortcomings of such equipment, first of all, increased noise generation caused by the operation of a powerful fan is noted. For the correct operation of the unit, it must be serviced regularly, i.e. purchase and timely replace carbon filters.

These items cannot be cleaned or refurbished, so the cost of operating the instrument may be higher than expected. In addition, good equipment of this type is quite expensive in itself.

An island umbrella can be installed right in the middle of the kitchen, if the size of the room allows. In a small room, such a device can be placed above a stove installed by the window.

Extraction equipment in the kitchen is always necessary. Particles of grease, hot steam, soot, drops and other contaminants may not be noticeable at first glance, but over time they form a layer of dirt on various surfaces that is not easy to remove.

In addition, gas residues that can enter the kitchen air and the smell of accidentally burnt food are not good for the health of others.

According to the device, the ventilation umbrella is a steel dome-shaped case, inside of which there is a fan and a set of filtration elements. To collect relatively large particles, a special aluminum grate is designed to protect the ventilation turbine.

In catering establishments, powerful exhaust hoods are mandatory for use over cooking surfaces. Similar devices are used to remove harmful fumes in other industrial productions.

An acrylic filter is usually used to remove a significant proportion of greasy contaminants. In installations with recirculation, it is mandatory to use a carbon filter, which performs fine air purification. Spark arresting mesh protects the elements from overheating and possible ignition.

It is especially necessary if the umbrella is installed above the appliance with an open flame. All filter elements must be cleaned or replaced periodically. Charcoal filters are replaced as soon as they become dirty; these elements cannot be restored.

Some types of acrylic filters can be washed and reinstalled, but this treatment quickly loses its shape, so the number of cleaning and recycling cycles is limited.

The exhaust hood must be large enough to cover the parameters of the cooking surface being processed by at least 100 mm

A fan or ventilation turbine built into the umbrella ensures air circulation in the right direction with the required intensity. The performance of this element provides the total power of the hood, which should be correlated with the total volume of the room in which it will be installed.

A very part of the umbrellas-hoods are equipped with lighting, which is very convenient. Such lamps can be used as additional lighting for the kitchen. Along with conventional incandescent lamps, halogen or diode lighting fixtures are built into the hoods.

The latter provide a sufficient level of illumination with minimal consumption of electrical energy and increased service life.

At industrial catering establishments, exhaust hoods are installed above various types of devices: stoves, grills, ovens, etc.

If the umbrella is connected to the ventilation duct of the house, it must be equipped with special valves that prevent the air masses entering the device from returning to the kitchen.

Types of structures and the problem of choice

According to the type of construction, wall and island exhaust hoods are distinguished. The design can be exhaust or supply and exhaust. In the first case, the device only removes the exhaust air from the room, in the second case it also provides an additional influx of fresh air masses.

When choosing a suitable umbrella, consider the required level of air exchange, the size of the cooking equipment, as well as the intended location for its placement. For an industrial kitchen, it is recommended to install a model whose dimensions are 100 mm larger than the dimensions of the hob.

For the manufacture of such devices, food-grade stainless steel is used. The device is usually equipped not only with a grease trap, but also with a carbon filter. Backlighting can be a useful option. Supply exhaust devices, as the name implies, provide not only the removal and purification of polluted kitchen air, but also the influx of fresh air masses from the street.

Such umbrellas are rarely used at home, this is a technique for professional use. Some operations require a constant supply of fresh air. Umbrellas of this type allow creating an exceptionally favorable microclimate in the working room, adjusting the humidity and air temperature to an acceptable level.

The power of the exhaust element usually exceeds the supply air capacity in models of this type by about one third.

The advantage of using a hood is that it can be installed in almost any suitable place, you just need to choose the right model

Wall umbrellas are fixed not on the ceiling, but on the wall. Typically, such models are used to connect to the exhaust duct. To facilitate installation work, the hob is installed as close as possible to the ventilation duct.

In this case, it will not be too long, which contributes to the efficient movement of exhaust air into the ventilation duct.

Wall-mounted exhaust hoods can be mounted on the wall. They are more convenient to connect to the ventilation duct of the building than island models.

The short design usually does not need to create many turns when using rigid plastic ducts. There should be no more than three such knees for one ventilation umbrella. The beveled type of island umbrella is very popular, which allows you to bring the hood to the maximum allowable distance from the hob.

An island-type umbrella, which is attached to the ceiling, is considered universal. As the name implies, it is used for installation above the kitchen island, specifically - above the stove built into it. The design feature is that during its installation there is no need to use a wall, the structure is attached to the ceiling.

Such devices are usually used in large kitchens, both industrial and domestic. In small areas, the use of a kitchen umbrella over the island is usually not used due to lack of free space. But such a design may be appropriate even in a small kitchen if the hob is installed near the window.

The presence of two filters allows you to clean the air at a sufficiently high level so that you can return it to the kitchen. Of course, you should use the necessary means to ensure sufficient air exchange, but recirculation allows you to save in the room part of the heat energy that was spent on cooking.

To remove polluted air using an exhaust hood, it must be connected to the ventilation duct. If this is not possible, models with circulation and carbon filter are used.

Recirculation is used in island hoods, since it is usually quite difficult to install such a unit next to a ventilation hatch. Read about how recirculation hoods work. Some models of island umbrellas can be adjusted in height, which allows you to change the intensity of absorption of polluted vapors depending on the situation.

If the place for installing the hood is chosen in such a way that the filtered air cannot be discharged into the ventilation duct, then a device with recirculation will definitely have to be preferred.

When choosing an exhaust hood for the kitchen, you should choose the right one. The most powerful option is suitable for a kitchen up to 25 square meters. m.

However, you should not choose a model with too much power, because the higher the performance, the more noise the hood makes during operation. For a small room, this can be a real disaster.

Distinguish exhaust and forced-air and exhaust umbrellas. The latter not only ensure the removal of polluted air, but also allow the influx of masses from the street to improve the atmosphere in the room.

The noise level of the device in the region of 40 dB is considered acceptable. It may be slightly higher (up to 70 dB), but you should not choose an excessively noisy model, since the sound of its operation can be annoying. When choosing the type of control, the installation height of the device should be taken into account. If the hood is installed high enough, the remote option can be very handy.

Such equipment has a high price, so when choosing a brand, you should pay attention not only to the well-known name, but also to the warranty period, as well as to the availability of service centers and warranty service conditions. Of course, the design of the device also plays an important role. Fortunately, models of exhaust hoods are very diverse, you can always find a suitable option.

Features of installation and operation

It is relatively easy to install this type of exhaust equipment, but it is still better for inexperienced craftsmen to entrust these operations to professionals. If it is decided to carry out the installation yourself, then you should start with a detailed study of the manufacturer's instructions.

Hoods are usually made from durable food grade aluminum steel. For industrial enterprises, such structures are often created on an individual order.

After that, you need to examine the installation site, take the necessary measurements, prepare tools, fasteners, materials, etc. An important point is the correct distance from the hob. It must be at least 60 cm for electric stoves and 70 cm for gas appliances, but not more than 85 cm.

If the umbrella needs to be hung higher, then a more efficient device should be chosen to compensate for the difference in height. To install a ventilation exhaust hood, you will need tools that are usually in the arsenal of any experienced craftsman: a tape measure and a building level for marking, a screwdriver, drill, hammer, etc.

Depending on the type of device, you will either need to simply hang it above the stove, or connect it with an air duct to the ventilation duct. Either a metal corrugated sleeve or rigid plastic structures are used as an air duct.

The corrugation can be bent in a suitable way, and to make a plastic elbow, special adapters should be used to ensure a tight connection of individual sections of the duct.

If the power cord is not long enough, you need to install an additional outlet near the device. You need to make sure that the appliance has the necessary grounding.

Proper installation of the ventilation hood is only half the battle. In order for the device to work effectively, it is necessary to organize its work. Detailed information on such matters is contained in the instruction manual supplied with each instrument.

Regular cleaning is of great importance. For example, aluminum grilles should be washed with special detergents. The use of products that can be found in any kitchen also gives a good result: acetic acid, diluted by a third with water, a saturated solution of ordinary laundry soap, or a pasty mixture of water and baking soda.

The aluminum grate traps of exhaust hoods should be regularly cleaned of dirt accumulated on them in order for the device to work correctly and efficiently.

These recipes are useful for those who suffer from intolerance to chemicals. Grids should be cleaned from accumulations of grease and dirt at least once every three months.

Charcoal filters are usually replaced in the following order:

disconnecting the device from the power supply;
dismantling of aluminum gratings;
removing the used filter;
installation of a new filter element;
installation of aluminum gratings;
connecting and checking the operation of the device.

At the time of installing a new filter, a characteristic click should sound. If, after replacing the filter, the hood makes unusual sounds or becomes noisier, the filter may not be installed correctly and the operation should be redone.

If the ventilation hood filters are not cleaned and replaced in a timely manner, the performance of the appliance may deteriorate significantly.

Charcoal filters are essential in circulating hoods, they finely purify the air and need to be replaced regularly

Removable filters and glasses for collecting fat in models of umbrellas that are used in catering establishments, in accordance with the instructions, should be cleaned daily. It is also necessary to constantly clean the outer surface of the housing of the exhaust device. Some elements are recommended to be removed and soaked in special cleaning solutions.

After cleaning, they are thoroughly rinsed. Another element that needs periodic cleaning is the air duct. It is necessary to remove the connecting elements and remove deposits from the inner surface of the structure.

Corrugated elements often need such cleaning than smooth plastic channels. Some industrial models of kitchen umbrellas are equipped with a built-in cleaning system, but such expensive units are usually not used in everyday life.

Conclusions and useful video on the topic

Cooking meat, fish and vegetables on the grill is a traditional, pleasant, festive affair, but it has its drawbacks. The process is sometimes interrupted by bad weather, and the smoke spreading around the yard creates a certain discomfort for others. To make barbecue bring only pleasure, use an umbrella for barbecue. The element is installed above the firebox and serves as a chimney.

Useful functions and principle of operation

Making the exhaust part with your own hands is a feasible task. The smoke collector for the barbecue performs two main functions:

Removal of volatile compounds. In fact, an umbrella is a chimney that raises the gases formed during combustion. As with the barbecue oven system, the action is based on traction. With sufficient combustion intensity, the smoke heats up to such a temperature that it becomes lighter than the surrounding air, and tends to rise. If an umbrella is installed, the combustion products do not have time to dissipate, but are collected in a pipe and released only at the end of the chimney. Thus, all unpleasant compounds disappear without harming a person.
Protection of the frying surface from precipitation. This is ensured by the presence of a smoke box, which, due to expansion, covers the entire brazier. Usually this function is performed by a gazebo or a canopy, under which a frying device is installed, however, an umbrella allows you to use the barbecue both under the roof and in the open area.

Umbrella design

Exhaust ventilation is a simple device. Accuracy is important in manufacturing, so it is recommended to use a drawing. The umbrella consists of 3 parts, each of which serves to gradually remove smoke:

materials

The choice of material for the exhaust device depends on the design of the barbecue. If the structure is brick, then both metal and brick are suitable for making an umbrella. How are these materials different?

Strength and rigidity. Masonry has greater mechanical resistance than metal. Of course, no one is going to drive into the brazier on a tank, but these qualities are useful during operation: the brick structure will not be disturbed by accidental impacts, strong gusts of wind, and with high-quality masonry it will not deform over time.
Service life. The metal rusts, burns out in the sun and at high temperatures, so the duration of its operation is much lower than that of a brick.
Complexity and production time. To make an umbrella from a sheet of steel, you do not need to have masonry skills, knead the binder solution and carry bricks. Making a hood out of metal is easier.
Cost cost. And on this point steel wins. Buying a sheet of iron will be much cheaper than buying bricks and mortar.

Both steel and brick umbrellas do their job well. There is no difference in the removal of combustion products.

Metal chimneys for: 1) barbecue, 2) barbecue

Features of brick construction

The basis of the dome is an iron frame welded from a strong corner. Before laying, it is treated with a primer and painted for better protection. Since the temperature directly above the firebox is quite high, the smoke collector is made of refractory bricks. The design form is stepped, narrowing.

Tip: file the protruding welds in the metal frame so that you do not have to cut the bricks in the masonry.

The chimney is made of both fireclay and oven bricks. If the brazier stands in an open area, drainage slopes are made of heat-resistant roofing material on the walls of the smoke box. Then, during precipitation, moisture will not destroy the building structure. The umbrella over the pipe is metal.

Metal umbrella

For the manufacture of the hood, durable stainless steel or sheet metal with a protective coating 2-3 mm thick is used. A whole sheet is drawn. Separately, parts are cut out for the collector, pipe and elements for the umbrella. After bending according to the shape of the cut parts, the seams are welded or fastened with rivets or latches.

Thematic material:

Installing an umbrella over the barbecue is carried out in different ways:

Through the chimney, a mixture of gases with products of combustion of fuel from fireplaces, stoves and heating boilers exits the street. Looking at private houses, you can see that the head of the pipe is crowned with a special visor or umbrella. At first glance, these devices, decorated with figured forging, intricate patterns and figurines, give the impression that they are just a decorative element. In fact, the chimney cap is an important element of the smoke exhaust system, the correct design and installation of which affects the efficiency of its operation. This article will talk about the principles of operation, types and methods of self-manufacturing of deflectors with your own hands.

A chimney cap is a device resembling an umbrella or a visor in appearance, installed on the head of the pipe in order to protect it from moisture. There is a huge variety of variations in the appearance of wind vanes, depending on the shape and size of the smoke exhaust duct. The design of caps of all types consists of the following elements:

Important! For a chimney, you can make a do-it-yourself cap from sheet metal, however, more complex models are easier to buy or order. The most convenient type of maintenance and operation is a protective umbrella with an opening lid. Due to the mobility of this element, the protective visor is not removed during.

To make a durable cap for use sheet metal that is not subject to corrosion. Do-it-yourself manufacturing from galvanized steel, copper or aluminum is common. The umbrella on the copper head has a noble shade, it looks respectable, but it often becomes a “victim” of non-ferrous metal collectors.

Varieties

The abundance of shapes and types of chimneys force manufacturers to produce caps of various shapes, styles, sizes. In construction stores there are products of the following types:

Standard flute. Her umbrella is a sheet metal pyramid attached to a drip apron with brackets.
Four-slope wind vane. The top of such models resembles a hip hipped roof. As a rule, they are used for rectangular brick pipes.
Wind vane with a semicircular umbrella. It is used for mounting on the roofs of European-style houses. From the point of view of increasing traction, it has low efficiency, however, it looks beautiful on a slope.
Flat flask. It is equipped with a flat rectangular umbrella, used for buildings in the style of minimalism and modern. The flat cover of the cap does not allow snow to roll down, which is why the brackets of such models are under increased load, sometimes deformed.
Round weather vane with an umbrella in the form of a cone. They are used to protect round pipes made of stainless steel; such models are not equipped with a dropper.

Note! Vanes are supplied with additional functional elements: dampers, double roofs, folding doors. Do not get carried away with elaborate details, because the main thing in choosing a deflector is durability and efficiency. An ill-conceived shape can cause noise or vibration in the pipe.

Principles of operation and functions

The cap on the chimney not only protects against the ingress of debris and water into the smoke exhaust duct, it affects the traction force. The air stream moving horizontally or at an angle is divided and goes down, this causes a "sucking" effect. Due to this, a zone with reduced pressure is created, into which smoke from the furnace rushes. The protective deflector performs the following functions:

Prevents the penetration of moisture into the chimney. Dampness in the chimney increases fuel consumption and creates favorable conditions for the spread of fungus.
Closes the pipe opening from branches, leaves, debris, as well as nesting birds. Umbrella reduces the risk of fire, blockages. Thanks to him, the chimney becomes less clogged and functions more efficiently.
Optimizes the operation of the chimney. A properly selected visor increases the efficiency of the chimney by 10-15%. And with the help of special aerodynamic deflectors with turbines, they solve the problem of lack of traction.

Important! Although the protective chimney umbrella is considered an element of decor, it is primarily a functional element of smoke removal. A properly selected deflector should not create noise or vibration inside the chimney duct.

DIY manufacturing

To make a chimney visor with your own hands, it is better to choose a simpler model. For work, you will need galvanized sheet steel, metal shears, bends, a marker, cardboard, a welding machine. The process is performed in the following order:

Important! It is easiest to make a do-it-yourself chimney cap if you make it from a sheet of metal curved in an arc. When creating a drawing, keep in mind that in winter the weight of the snow cap falls on the brackets, so choose a metal of sufficient thickness and strength.

When making an umbrella to protect the chimney from moisture penetration, accurately measure the dimensions of the pipe. A properly selected deflector model improves the appearance of the roof and optimizes the operation of the smoke exhaust system.

Video instruction

If you look closely at the chimneys and ventilation pipes of residential buildings, then the variety of chimneys on them (deflectors, weather vanes) is amazing. But the main task of the deflector is not to decorate the chimney, but to increase and stabilize the draft depending on the weather, and thereby improve the efficiency of the heater and reduce heating costs. The deflector on the ventilation pipe can provide non-volatile (and free) supply and exhaust ventilation, see below. But at the same time, there are also enough opponents of installing deflectors on the pipes of residential buildings, and they give weighty arguments in their favor. The purpose of this article is to help the reader figure out in which cases it makes sense to put a deflector on a chimney or ventilation, then how to choose the right one or make it yourself.

The most important question

Before choosing or making a deflector for a pipe, you need to decide - is it needed at all? The deflector can freeze, drag on with soot or soot (coke), clog with fallen leaves, wind-blown debris or dust. In any of these cases, if the deflector is on the chimney, the inhabitants of the house risk getting burned. The deflector does not increase the efficiency of the furnace or boiler much, but it requires regular inspection and cleaning. At least once every 3 months for solid fuel stoves and at least once every six months for gas, liquid fuel or pyrolysis stoves and boilers. For more information about the dangers that an unsuitable deflector can entail on a pipe, see the video:

Video: why are deflectors, umbrellas and weathercocks on the chimney dangerous?

Therefore, if you have an old wood or coal stove, but the draft is unimportant and the wind blows into the chimney, it is better to put a simple chimney instead of a complex deflector, for example. umbrella or tent. And in other cases, you need to carefully figure out which particular deflector is needed for this particular stove / boiler with this particular chimney. It is also important not to confuse a smoke deflector with a ventilation one - small merchants and authors of some popular publications do not see or do not see the difference between them.

deflector evolution

Deflectio in Latin means "I reflect" in the sense of "I discard". Not directed in a certain way, like a reflector, but only to the side. Chimney cap made of skins, large shells, etc. already set by primitive people to avoid wind blowing into the chimney.

The role of the deflector in creating thrust, its stabilization in spite of the vagaries of the weather and the ability of the deflector to increase the efficiency of heat-generating devices were first seriously thought at TsAGI almost 100 years ago on the instructions of the newly hatched Soviet government. Before that, heat engineers tried to improve chimneys for this purpose. Have you seen in old photographs the huge pot-bellied, like an inverted pear, chimneys of American locomotives or the long thin ones, with a rosette at the top, of English ones?

At TsAGI, the venerable aircraft designer D. P. Grigorovich took up deflectors in a creative collaboration with A. F. Volpert, who was fluent in mathematical apparatus. The latter is also, and even more, known for his work in the field of radio engineering (Volpert-Smith diagram, etc.). Together and separately, Grigorovich and Volpert developed several types of deflectors for various purposes, therefore, different deflectors of Grigorovich, Volpert and Volpert-Grigorovich are described in the specialized literature.

Grigorovich began by aerodynamically correctly calculating the usual chimney-umbrella, pos. 1 in fig. This has already significantly improved the performance of the device; Grigorovich's cone - remember, it will come in handy. Volpert proposed to equip the deflector-umbrella with an aerodynamic diffuser skirt (pos. 2), but the deflector remained aerodynamically imperfect, see below. It was supplemented with a streamlined body of revolution instead of a cap and a cylindrical body-shell. In the end, after repeated blows in the wind tunnel, the TsAGI deflector (pos. 3) was presented to the government commission, which fully met the issued TOR and greatly overlapped it.

The TsAGI deflector is still the most common in the world due to its technical excellence. There are modifications for different purposes, see below. But other developments of Grigorovich and Volpert were not in vain - most of the models of modern smoke deflectors are being developed on their basis. Which of them is more suitable for what, we will talk about this later.

Types and schemes

All the variety of trade names of smoke deflectors fit into a limited number of design types and aerodynamic schemes. First of all, according to the interaction with the natural draft of the chimney, the deflectors are divided into:

Active - with a built-in working smoke exhauster. To ensure the specified characteristics of the deflector, the smoke exhauster must work constantly while it burns in the furnace.
Active-passive - a low-power smoke exhauster in case of emergency: complete calm, storm, excessively intense firebox, etc. The minimum allowable technical characteristics of the chimney are also provided when the exhauster is switched off.
Passive-active - the deflector creates a small amount of its own thrust in a non-volatile way.
Passive - there is no deflector own draft.

We do not consider active deflectors as volatile and not optimal for low-power house heating appliances. Of the active-passive ones, one will be considered, designed for a low-power 12 V fan and suitable for DIY.

According to the aerodynamic design of the chimney deflector, it is possible to perform the following. like this (top of the picture):

Aerodynamically imperfect (incomplete) - in the space occupied by the deflector there is a “pocket” - a winding area in which accumulation of air, flue gases or their mixtures is possible;
Aerodynamically full open - there is no wind pocket, but the wind has free access to the deflector working space;
Aerodynamically perfect closed - there is no wind pocket, the wind does not have free access to the working space;
Weather vane deflector (see below);
Vortex deflector.

An aerodynamically perfect closed deflector is the most complex structurally and technologically, but it has a huge advantage: due to the heating of the shell, aerodynamically perfect closed deflectors almost all produce their own non-volatile thrust. This is the only passive type of deflector that can increase the natural draft of the chimney at full calm.

Note: an aerodynamically perfect closed deflector is the TsAGI deflector mentioned above. This aerodynamic scheme was invented in TsAGI.

Vortex deflectors are easily recognizable by their "torn" design with sharp protrusions. In their aerodynamics, as well as in vortex aerodynamics in general, there is still a lot of uncertainty (the Navier-Stokes equation was solved in general form only 2 years ago). It is impossible to predict the behavior of a swirl deflector under any external conditions with any chimney. Therefore, vortex deflectors are not considered further. To believe or not to their manufacturers is your own business.

Aerodynamics

Schemes of flue gas current in deflectors in publicly available sources are sufficient. But from the point of view of the homeowner and the master, the nature of the interaction of the deflector with the natural draft of the chimney and the wind in the wake is more important. aspects:

Will the deflector worsen the initial draft?
Is the deflector able to increase the initial draft in calm?
To what extent and in what way does the deflector increase wind loads on the pipe?
How prone is the deflector of this scheme to icing / clogging and easy to clean?

The wind is then better considered not on the meteorological scale, but on the basis of a rough gradation of force and the dynamics of the velocity field:

calm;
weak / medium (moderate) - up to 6 points on the weather scale;
strong - 6-8 points;
very strong - over 8 points;
gusty - the wind of any strength is really gusty, or sharp (very sloping up or down), or swirling.

Figure 1 gives an idea of the aerodynamic properties of passive smoke deflectors. higher.

simple cap

An ordinary chimney chimney in the form of an umbrella, if it is made in the form of a Grigorovich cone, is not so bad:

With a massive heat-intensive chimney, it keeps draft within the limits allowed for a wood / coal stove in an even wind up to a violent storm (10 points).
In any wind up to a hurricane, it does not create destructive loads on the pipe; Rather, he will break and fly away.
Structurally simple.
Slightly coking and clogging, easy to clean as part of the annual inspection and maintenance of the chimney.
Due to imperfect aerodynamics, it is not very sensitive to the configuration of the umbrella. If the house is in the wind, the chimney-umbrella can be made tented (see the figure on the right), which simplifies the work and gives great opportunities for its design.
With a 2-3 channel chimney (see below), it provides technical indicators (except for an increase in draft in calm weather) no worse than an aerodynamically perfect closed deflector.

The disadvantages of an imperfect chimney deflector are also quite serious:

In calm weather, it reduces the initial draft the stronger, the more intensively the stove is heated. What is especially dangerous in a harsh, quiet winter: the stove can choke and puff with fumes.
In strong winds, it is able to create excess traction, which dramatically reduces the efficiency of compact channel stoves (for example, Dutch ones by 2.5-3.5 bricks) and fireplaces.
In very strong / gusty winds, blowing into the pipe and the appearance of reverse thrust are not ruled out.

In general, an imperfect deflector-umbrella is the optimal chimney for a brick chimney of a properly built and well-maintained house solid fuel stove, operated in places where hurricanes and storms are extremely rare. There are ways to make the chimney-umbrella non-inflatable (see below), but they complicate it to the point that most often you have to choose an aerodynamically complete or perfect deflector.

Open

The aerodynamically open deflector does not reduce the initial thrust and in any wind keeps it within the limits allowed for furnaces and boilers for solid, liquid fuel and gas. It freezes quite strongly, cokes and litters, but is easily accessible for cleaning. Its disadvantages are:

A streamlined body of revolution instead of a cap is a technologically complex assembly.
The resulting vector of wind loads is such that the aerodynamically open deflector tends to collapse the pipe, while the umbrella tends to fly off it itself.
In a wind stronger than 8 points, the lateral load on the pipe increases sharply and then grows according to a power law.
It poorly extinguishes the dynamic load from gusts of wind, therefore, an open deflector cannot be placed on a brick pipe.
Unsuitable for pyrolysis heat-generating devices: in a strong wind, it immediately sucks out pyrolysis gases and the furnace / boiler goes out.
Little suitable for design: blotches and figures spoil the overall aerodynamics. The only place where decorations can be placed is the upper pole of the body of rotation and the lower edge of the diffuser (see below).

Note: At one time, we and the USA conducted experiments on the use of open deflectors on steam locomotives to increase efficiency at low speed. The result is deplorable - at the middle stroke, a tongue of flame was shown from the pipe, and none of them could accelerate to the design speed.

In general, the aerodynamically open deflector is suitable for all types of heaters, except for pyrolysis ones. Provided that the deflector is inspected and cleaned at least once every 2 months, and the draft is checked before each firebox. It is very well suited for chimneys with insufficient draft, and especially for sauna stoves: there have been no cases of burning in saunas due to an open deflector. Correctly heating a bathhouse is not an easy task, and checking the deflector will not noticeably complicate it.

Note: there are types of open deflectors that practically do not create side loads on the pipe and are suitable for fragile ceramic and glass chimneys, see fig. on right. However, dust, debris and soot accumulate in the open body of rotation, which spoils the aerodynamics of the device, and it is difficult to clean it. Therefore, manufacturers recommend such products only for gas boilers in places with not very dusty air.

Perfect

The advantages of an aerodynamically perfect closed deflector are partially indicated above. Besides:

The aerodynamically perfect closed deflector provides draft stability in any external conditions, sufficient for any household stoves and boilers.
It does not clog and does not freeze inside, and frost and dust from the outside have little effect on its operation.
With minor modifications, it is suitable for use as both smoke and ventilation non-volatile, see below.
It perfectly dampens the dynamic load from gusts of wind and is therefore suitable for installation on pipes made of any material.
2-3-4 chimneys can converge into one oval, triangular or square shell.

The disadvantages of a closed deflector are not so significant:

The lateral force on the pipe in the wind up to a strong one gives more than the open one, but then with the strengthening of the wind it grows linearly, i.e. the pipe under the open deflector can always be reinforced or strengthened with braces.
It is quite complicated structurally and technologically.
Unsuitable for design: any blotches and figurines spoil the overall aerodynamics, and the coloring only enhances the utilitarian look of the deflector.

Technological tricks

The first rule - do not make chimneys like a gable roof or a cylinder vault (see the figure on the right). Such are suitable for their intended purpose only for mobile devices, when the axis of the umbrella can be arbitrarily oriented along the wind. Or as decorative on a false chimney. There is such a fashion in houses with biofireplaces. And in other cases, the thrust will walk according to the will of the elements up to the reverse.

Further, in order to make a deflector for the chimney with your own hands, you need to master some of the techniques of tin work. First of all - the connection of sheets in a fold (fold), or folding, see fig. below. Most often, the details of the deflectors are connected by a single lying fold, but for the umbrellas of imperfect deflectors, a double standing fold is sometimes used for decorative purposes.

Umbrella round:

Umbrella pyramidal (hipped) with a top in the center:

Umbrella elongated faceted:

Transition from a square to a circle (square inside a circle):

Very important for closed deflectors for small furnaces and boilers, see below.

Moving from circle to circle:

All these patterns can be built using only a ruler and a compass - a goat's leg (into which a pencil is inserted. Well, for those who are prone to in-depth study of the basics, before getting down to business, we give a selection of projections and formulas for accurately constructing sweeps of parts. Pay attention to the elongated umbrellas: they are placed on 2-3 flue chimneys.Smoke channels, each of the minimum cross section allowed for a given heater, are placed in a row.The probability of blowing out 2 channels at once is extremely small, and all 3 are practically absent.

Here in fig. - data for constructing a truncated cone, which are more than enough in deflectors. The initial data are the height of the cone H, the radii of the top and bottom R1, R2. Pay also attention to the inset marked in red: this is a development of the same Grigorovich cone. The forming angle (in this case 30 degrees) is found as φ = arcsin(H/r), where H is the height of the cone and r is the radius of the base. The radius R is defined similarly to L for a truncated cone, but H and r are squared. However, for those who have not forgotten the Pythagorean theorem, this is already clear.

After the cones, it will not be difficult to deal with the development of a single-center tent, see fig. Only one “but”: the allowance on the pattern example (on the right in the figure) is given per single riveting (for strength) of the soldered seam.

To connect metal up to 0.6 mm thick into a single fold, the allowance on one side must be taken 20 mm, and on the other 21 + 2 + 20 mm. If the metal is 0.6-1.5 mm, then 30 and 31.5 + 3 + 30 mm, respectively. But, generally speaking, a seam soldered and riveted at the edge is easier to make, it looks neater and resists corrosion better than a seam. If the roof is covered with iron, then, of course, riveting and soldering the sheets is simply technically impossible. But the deflector umbrella is another matter. Collect it on soldering with riveting as follows:

Mark and cut out the scan;
Drill holes for the rivet;
The sides (wings) of the allowance are bent inward at 90 degrees;
Rivet the edge;
Through the wooden lining bars, the sides are compressed with clamps;
Solder the seam.

In a similar way, a sweep is built and a hip tent (umbrella) of the chimney is assembled, see fig.

And, finally, the most difficult detail: the diffuser of an aerodynamically perfect closed deflector, which is also an adapter-skirt from a square to a circle (circle inside) for installing a chimney-umbrella on a brick pipe. The construction rules are not complicated (see the figure), but they require accuracy and accuracy in work.

Note: it is possible to additionally equalize the draft of the open and imperfect deflectors on a round pipe, as well as to reduce the probability of blowing into the latter to an insignificant extent, if the diffuser / skirt generatrix is bent inward, see fig. But the work is so complicated - after assembling the adapter from circle to circle, it must be knocked out on a block of solid wood.

Constructions

Now let's see what is possible and how to make a deflector on the chimney yourself. The easiest way to start is with an imperfect umbrella deflector; its possibilities are much wider than it might seem, and it takes a little material and not very complicated work.

What can an umbrella do?

In the climatic conditions of the Russian Federation, a deflector-umbrella on a chimney most often turns out to be enough, especially since no waste was also noted through his fault. But - if the chimney-umbrella is made correctly. The most common mistake is to raise the cap too high on the racks. It will not help to return 100% of the original thrust, but the likelihood of blowing into the pipe increases dramatically.

The correct dimensions of the deflector-umbrella on the chimney are given on the left in fig. For pipes with a clearance of 100-200 mm, they decrease proportionally, and then the value of H1 increases 1.3 times for pipes 150-200 mm and 1.6 times for pipes 100-150 mm.

On the right in fig. the dimensions of the non-blown deflector-umbrella are given, but in the conditions of the Russian Federation it is better to put this one on the ventilation pipe of natural ventilation, because the grid is quickly overgrown with soot or flue gas condensate, and then dust adheres very well to it.

It also does not blow out, retains the original thrust and even slightly increases its two-story deflector-umbrella. The scheme of its action is given in pos. 1 next rice.:

For chimneys of low-power household stoves / boilers (up to approx. 40 kW), it can be simplified by making the floors the same, pos. 2. Each floor is a Grigorovich cone cut in half in height (see above); the distance between floors is equal to the height of the floor. The upper floor is gable, i.e. the cut top of the cone is closed with a blind lid. A 3-story umbrella for a ventilation pipe (pos. 3) is less likely to freeze over and clog less than an umbrella with a net. For pipes 130-200 mm, the dimensions change proportionally. And, finally, the Kiryushkin deflector (pos. 3; all cones - Grigorovich) is used mainly as an active-passive one - a low-power smoke exhauster for 12 V 100-200 mA is placed under a small cone.

TsAGI

Before taking on an aerodynamically open deflector, let's see how the most advanced TsAGI deflector is modified for a private house. Its original design was designed primarily for industrial facilities and then for apartment buildings.

Drawings of 3 variants of the TsAGI deflector are given in fig. The dimensions of the original industrial version are shown at the top right. Not completely, because it is designed for a strong pipe and certainly not for a sandwich chimney. For the chimney of a private household, the Khanzhenkov deflector operating in the same way is more suitable (on the left in the figure). It gives less horizontal wind load and can be inserted into the pipe as described below.

And on the right in Fig. - dimensions of the TsAGI ventilation deflector. It can be turned from passive into passive-active by painting the shell with black blacksmith's stalemate or other paint that well absorbs the thermal radiation of the earth and the objects surrounding the house. Fans in the vents of the house ventilation system must, of course, be left, but they will have to be turned on occasionally. How to make a TsAGI deflector with your own hands, see video

Video: do-it-yourself TsAGI deflector from metal tiles

Note: a ventilation deflector is not such a luxury as it might seem. When the wind blows into the ventilation, it is cold in the bathroom, and kitchen fumes and toilet smells are carried around the house. Flapper valves do not solve the problem - it slammed shut, it was stuffy in the bathroom and kitchen.

What is obtained from the cones

Of the open-type deflectors, the Volpert-Grigorovich deflector is the most affordable, and, for the entire range of technical indicators, the Volpert-Grigorovich deflector is optimal for private households. Although, only they themselves knew how much it actually contained.

The canonical (original from TsAGI research) proportions of the Volpert-Grigorovich deflector are given in pos. 1 fig.:

On the left - a modification for an asbestos-cement pipe, which holds longitudinal loads well, but is fragile across. The doubled height of the upper cone forming the body of rotation gives a large lifting force, tending to rip the deflector off the pipe, but a tight collar will keep it in any wind. For pipes 130-180 mm inside, the dimensions change proportionally.

Note: for another version of the self-made Volpert-Grigorovich deflector, see next. video clip:

Video: Volpert Grigorovich deflector to increase draft in the furnace

weathercocks

Deflectors for pipes - weathercocks are also called weathercocks. Sometimes all chimneys in general are called that, but this is not true, because. weather vane by definition is a rotary device.

The deflector on the pipe - the weather vane can be made rotary self-orienting and rotating. The latter are also called turbo deflectors, and self-orienting smoke teeth, which is also not true. Smoke tooth - part of the chimney of an English fireplace. The weak point of all wind vane deflectors is the bearing. It is very easy to clog and soot, and the seals are subject to increased wear. Therefore, it is necessary to inspect the deflector-weather vane at least once every 2 months. But the deflector-weather vane itself is almost never overgrown with the main enemy of all fixed deflectors - icicles.

Pipe deflectors - weathercocks

The multi-blade deflector-weather vane (pos. 1 and 2 in the figure) gives stable draft in the wind up to 9-10 points with slight loads on the pipe, so it can be installed on sandwich, ceramic and glass chimneys. A single-blade deflector-weather vane in a strong wind heavily loads the pipe, so it must be strong and the house should be located in a place where the storm wind does not clear up. But a single-blade deflector-weather vane is easy to arrange in the form of a bird (pos. 3 and 4).

Turbo deflector (pos. 5) - remember and do not trust anyone - not smoke! It is ventilated or for gas boilers with electric ignition. The turbine is rotated both by the wind and by the air flow in the pipe, and a correctly made turbine, as in some types of wind engines, is self-winding: the weakest initial thrust or a slight breeze is enough for the turbine to spin and draw air, and it will stop only when the thrust and the wind will stop completely. In the ventilation system of a house with turbo deflectors, you have to turn on the fans in the vents, as they say, once a year, not every year. Unfortunately, the turbo deflector is easily drawn in by dust and debris from the air, so it should also be checked at least once every 2 months.

The technical properties of the turbo deflector are the same as those of the multi-bladed self-orienting deflector, but it loads the pipe even less. It is quite possible to make a turbo deflector with your own hands, see the video below.

Video: do-it-yourself turbo deflector

How to install a deflector

It is possible to put a deflector on the pipe only if the chimney is made exactly according to the rules of SNiP 41-01-2003, pos. 1 in fig. below. It is highly desirable that the pipe on which the deflector will be installed is located on the leeward slope of the roof relative to the direction of the prevailing winds. For reference: leeward means opposite to the direction the wind is blowing from.

It is certainly possible to attach a deflector to an otter (upper extension of a brick pipe) only if the pipe was originally designed for the deflector. If not, or there are even the slightest violations in the pipe laying, the deflector must be attached to it as shown in pos. 2 pic:

A strong sleeve (glass; square-to-circle adapter) C is inserted into the pipe;
The glasses are fixed with blind anchors A at a level not higher than the bottom row of the otter masonry and with embedded pins Z into the grooves at the mouth of the pipe. Anchors and mortgages are bricked up with cement-sand mortar from M200;
A diffuser / skirt D with a cornice (shine) K is put on the glass. Mandatory for a deflector of any scheme, incl. imperfect!
The diffuser is attached only to the masonry with small anchor bolts. Not with self-tapping screws in plastic dowels! The skirt / diffuser is not attached to the glass!
On the collar (upper edge) skirts / diffuser firmly fix the working structure of the deflector.

Only with this method of fastening, the deflector will never loosen the old and / or brick pipe not designed for it.

It should be noted that the umbrellas of ventilation systems have a completely uncomplicated design. A rectangular chimney umbrella consists of a main body, a grease collection tray and filters that perform. Filters are always installed at an angle of exactly 45 degrees Celsius.

If we are talking about supply and exhaust hoods, then in this case it is imperative to use a grill or a device such as a diffuser.

In some cases, air duct umbrellas are also equipped with additional elements, such as connection ears, fans, lamps and many others.

1 The principle of operation of the ventilation hood

This device works as follows. The air that is processed to become hot has a much lower density and therefore rises to the top to be replaced by cold air currents.

Then the air enters the pipe and passes through special grease filters, where it is saturated with a large amount of oil vapor, due to which it begins to cool over time.

In the end, passing through such a pipe due to strong temperature changes, the oil condenses, air flows begin to separate from it and allow the fat to drain into the bath through special channels.

In turn, the air, which after such a process is purified, enters the round or.

2 Device classification

Today, two types of rectangular umbrellas are used for the chimney:

Hoods . Their main purpose is the complete elimination of unnecessary gases, substances, combustion products from the chimney. Heavily heated air streams are drawn in by an umbrella, after which they are transported through a pipe where grease filters are located and are eventually transported back to the air duct, with the help of which they are removed from the building. All this can be easily done by hand.
Supply and exhaust umbrellas . Thanks to them, both the exhaust of polluted air and the supply of new, clean air into the room are ensured. These umbrellas are best used in those rooms where, due to certain circumstances, the flow of clean air is limited. It is always necessary to carry out the calculation, taking into account the fact that the volumes of supplied and exhausted air flows will always differ from each other. Therefore, in no case should you rely on the fact that exhaust hoods will contribute to the complete destruction of odors, gases and other substances. Although the chimney, of course, will work much more efficiently.

There is also a classification according to the type of construction. So, exhaust and supply-exhaust rectangular and round umbrellas are divided into island and wall.

2.1 Do-it-yourself installation and calculation features

I would like to note that installing such umbrellas with your own hands is quite real, since in fact there is nothing complicated in such work. Below are some of the most popular ways to install a chimney umbrella.

Method number 1. Installation of wall exhaust hoods using anchors. After a certain calculation, the length of the umbrella is selected and 2 or 3 equal holes are drilled in the back of the wall. Using enlarged models of washers, the exhaust hood is first attracted, and then installed on the wall. It is very important that the wall is perfectly flat.
Do-it-yourself installation of rectangular umbrellas through collets and studs to the ceiling. At the very beginning, it is necessary to drill 4 identical holes for the studs. All these holes are drilled strictly along the edges of the umbrella, after which the device is attached directly to the ceiling. A modern chimney works perfectly if this option is used. The only negative, the calculation of the ceiling height to the standard length of the stud, does not allow the use of this technology if the height of the room is more than 4 meters.
Installation of exhaust hoods for the chimney using various cables and chains through anchors and brackets to the ceiling. In order to do everything with your own hands, you need to weld 4 brackets of the required parameters to the upper horizontal part of the umbrella, after which, using a carabiner, securely fix the chain or cable. The second end of such a chain or cable must also be securely connected to the ceiling. Among the disadvantages of this method, one can note the precariousness of the structure, so it is not at all easy to tie it with air ducts, but such a scheme is perfect for a chimney.

As you can see, it is not at all difficult to do the installation yourself. The main thing is to adjust the umbrella as close as possible to the chimney pipe and take into account some of the nuances.

Application area

Supply and exhaust and exhaust hoods of ventilation systems are widely used today by industrial enterprises and not only. Such systems are widely used in public catering establishments, such as restaurants, canteens, bars, food processing plants, cafes and so on.

Also, the installation of umbrellas is carried out over all kinds of devices of thermal equipment, in particular, this applies to deep fryers, gas stoves, and ovens. If the calculation allows you to install such umbrellas, then they are also used in various industrial premises - food, pharmacological, physical, chemical.

2.2 It looks like a ventilation rectangular umbrella - video

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