Fan in the chimney to improve draft: types of devices and instructions for inserting

Draft is the natural movement of air from a heating unit into the external environment when removing fuel combustion products from the residential area.
The process of burning fuel in a furnace depends on its strength: if it is insufficient, the fuel will burn slowly; if the draft is too strong, a significant part of the thermal energy will be released into the atmosphere. Lack of draft is also dangerous because some of the combustion products can enter the living space, causing serious poisoning among residents, even death. In addition, violation of the chimney exhaust conditions can cause a fire. The temperature of the flame when burning soot is such that even heat-resistant bricks burn out.

Controlling the hood is an indispensable condition for safe, comfortable living in the house.

Eliminating backdraft

If there is no draft in the chimney, you need to know a few basic rules to get rid of it.
Never start this process, even if you notice that the cravings have become a little worse, immediately sound the alarm, take steps, look for the reason. Do not forget to clean the chimney on time, make sure that no debris or other objects get into the shaft. It is recommended to immediately install a visor as protection.

Installing a deflector will help eliminate backdraft in the chimney. This device looks like a fan, which will spin due to the wind and “suck” air into the channel. Additionally, you can install a regulator, which also allows you to get rid of the problem with “return”.

In general, based on the original reason for the loss, do this or that work

Please note that no device can correct the design errors of the channel; here you will only need to rebuild or modernize the chimney

Scope of use of chimney fans

Such devices have found application in many areas of life. Fans are an integral part of the heating system. It is important to understand that a fully functioning and properly functioning chimney is a necessity. This is the only way to not worry about your health and the health of your family members. By installing a chimney fan yourself, you will protect yourself and your loved ones.

Here's where fans can be used:

• when arranging a fireplace;
• for heating system;
• when creating a sauna or bathhouse;
• for the forge.

It turns out that wherever there is a chimney, it is recommended to install a fan. This is provided that the thrust in it is small.

Making a deflector with your own hands

To make sketches of the device parts, you need to measure the internal diameter of the chimney and calculate their dimensions.

You can make a deflector for any pipe size yourself

To do this, we present several defining relationships:

• the width of the diffuser is determined depending on the internal diameter of the pipe by multiplying by 1.5;
• the width of the umbrella should be 1.7 in relation to the same parameter;
• the same coefficient is used to determine the height of the device.

After calculating the dimensions, you can begin making part developments. They can be done on whatman paper or any other thick paper.

The paper parts need to be assembled into a finished product using paper clips or a stapler, and try it on the chimney pipe. If necessary, make adjustments to fit the product to the pipe.

To make the deflector, galvanized or stainless steel sheets with a thickness of at least 0.5 millimeters are used.

Using the development of the parts, you need to transfer their contours to sheet metal and cut them out with bench scissors.

Assembly is carried out in accordance with the preliminary design.

Tools and materials for making a deflector

To make such a device, you will need the following:

• steel sheet;
• metalworking scissors for cutting metal;
• drill with drills of the required sizes;
• hammer;
• pliers;
• fasteners;
• marker for marking parts on metal.

The procedure for making a deflector

The production technology consists of sequentially performing a number of operations:

1. Transferring the contours of parts onto a metal sheet using a marker. You need to get the following parts - cap, stand, diffuser and outer cylinder.
2. The blanks for the cap, diffuser and cylinder are rolled to size. Connections are made with rivets or screws, and sometimes semi-automatic welding is used.
3. To install the cap you will need strips of metal. They are made from waste from cutting the main parts. You need to drill several holes on the cap and secure the parts with rivets.
4. The opposite ends of the strips are secured to the diffuser in the same way.
5. The resulting product is fixed to the shell.

Fireplace hood

Fireplace ventilation is a dome-type hood. It got its name for its resemblance to the air duct element of a classic fireplace. Today, fireplace hoods have become especially popular, because with their help you can not only clean the air from combustion products and food odors, but also create a cozy kitchen interior. Devices of this type are corner, wall, island and inclined. A wide selection of these designs allows you to place them in kitchens with any design lines from classic to modern and high-tech style. Dome structures have a lot of advantages and do an excellent job of cleaning the air.

Advantages of dome ventilation

Dome hoods are a classic option for kitchen ventilation. They owe their popularity to undeniable advantages over other devices, namely:

• Universal design. Domes do not need to be masked or built into furniture; they fit perfectly into any interior, adding sophistication and comfort.
• High performance. Fireplace hoods for kitchens belong to the class of flow-through ventilation systems; they have high power and performance.
• Easy to install. Installation of a dome vent does not require any special knowledge or skills. You can install it yourself by following the instructions.
• Affordable price. A wide variety of models allows you to choose a dome in any price category, which makes it accessible to almost all consumer groups.

Causes of poor chimney draft

From time to time, fireplace owners notice a deterioration in the performance of their heating device. Naturally, they don’t know what this is connected with. Experiments with changing fuel usually also lead to nothing. Experts say that the cause of poor fireplace performance is poor draft.

Causes of poor chimney draft

"Classic problems":

1. The pipe diameter is too large or small. The pipe must be the correct size. If its diameter exceeds certain standards, then reverse draft occurs. Bring the fan close to the chimney, if its blades begin to move, it means you have backdraft. A pipe that is too narrow leads to a reduction in thrust to critical levels.
2. Rotating elements and bends in the pipe. The chimney must be straight, otherwise you will have to install a chimney draft amplifier. Extra turns and bends significantly reduce this parameter.
3. Lack of tightness. This problem often occurs in brick fireplaces as a result of poor construction technology. When a small hole appears in the wall, it begins to work on the principle of a black hole, sucking in air due to the pressure difference. The presence of additional air negatively affects the traction force. This is the same as placing a fan to the side of the upward air.

If none of the above problems are similar to yours, then an amplifier will help solve your traction problems.

Smoke draft deflector

Step-by-step instructions for creating a brick chimney with your own hands

Building a high-quality brick chimney is not an easy task and it is very important to carry out the masonry so that everything is airtight, fireproof, and every seam plays a big role here. The priority direction of the functioning of the chimney is the removal of smoke and fumes from burnt fuel using draft, which not only draws out, but also supplies air flows into the firebox, and due to this, the combustion process is supported and ensured

Do-it-yourself brick chimney construction diagram

The big advantage of such a chimney is that it has good draft in all weather conditions and has an increased service life compared to metal pipes. Let's look at the question of how to build a brick chimney with your own hands according to all the rules.

We advise you to study in more detail the recommendations: what to make a chimney from in addition to this article.

Brick chimneys are laid in three steps:

Step 1. Carrying out preparatory work and laying the foundation.

Brickwork for the foundation of the future smoke exhaust duct

At this stage, you need to carefully familiarize yourself with the construction drawings of the future chimney duct. For an ordinary and traditional wood-burning stove, complete masonry is required; for a brick chimney for a gas stove, a metal pipe made of a specialized alloy will definitely be required as an addition. Before you begin laying out a brick chimney, you should build a foundation. Construction is carried out from solid brick or reinforced concrete.

The second stage of constructing a brick chimney with your own hands. Masonry

The chimney is built at a height of five meters or not lower than the roof ridge, as this plays a big role in draft. This type of chimney is laid exclusively with specialized fire-resistant or solid red brick. To bind them, a solution of cement and sand or limestone is used, and for places with particularly high temperatures, a specialized mixture is needed, used for stove masonry.

To break off the required piece of brick, you will need a grinding and cutting machine and a marker (felt-tip pen) for measuring. Using these tools, it is possible to create plates that are absolutely accurate in size, which will be needed in the field of otter, as well as cutting.

Brickwork chimney for a gas heater

When constructing such a smoke exhaust duct, it is imperative to leave specialized openings for cleaning.

Holes at the top of the smoke duct made of brick for smoke exit and cleaning

The inside walls should have a perfectly smooth and even surface, and the corners should be 45 degrees. It is best to plaster the inner walls for smoothness, since soot will settle more on a rough surface, thereby worsening traction. This may cause a fire, which is unsafe. Also, many experienced stove makers recommend whitening the stove not only inside, but also outside, which will allow you to immediately determine where smoke and soot can seep in.

Stage 3. Fastening and thermal insulation.

If the chimney is built near a wall, it needs to be secured - this will be more reliable. To do this, you need to use metal anchors at a distance of thirty centimeters. Where the chimney will be connected to the ceiling, as well as the roof, it is imperative to place non-flammable material or glass wool, thereby reducing the risk of fire.

The brick chimney should be half a meter above the roof ridge. The upper part of the smoke exhaust duct should be insulated and covered with a specialized roofing finish or brick for cladding.

Fastening brickwork to the wall using anchors for reliability

If the chimney is made according to all technologies, it will be strong, safe, reliable and will last a long time. All these stages are preserved if you need to build a chimney for a solid fuel boiler made of brick.

Video: stages of building a brick chimney

You can line the chimney with bricks yourself, following the advice, and save on calling professionals. The main thing during construction is to build the right drawing and have free time. You should not rush, speed is not the best indicator here, you need to focus on the quality of the masonry.

Traction and possible accidents

First, about traction, and about those processes with which many owners of heating devices may be familiar first-hand.

What is traction?

Air circulation is a natural process that allows oxygen to flow into the combustion chamber and then release exhaust gases through the pipe. The movement of air and gases in the chimney occurs due to the lower density of the heated air. For this reason, a pressure difference occurs in the lower and upper parts of the channel.

Draft in a chimney is natural ventilation, consisting of exhaust and inflow. Hot gas, which has excess pressure and lower density, tends to the area where it is lower - upward. Cold air coming from the street takes up the free space. Combustion in the firebox is provided by air that continuously enters the chamber from the room, and then “travels” along the chimney channel and goes outside.

Backdraft

Reverse draft is a similar process, but the movement of gases or air is exactly the opposite. This situation occurs when the pressure at the top of the channel is higher than at the bottom. Reverse draft is a stable, but reverse circulation: in this case, flue gases return to the room along with the air that enters the chimney from the street. There are quite a lot of reverse thrust provocateurs. These include:

• mismatch of system elements - height, diameter of the vertical part of the chimney and parameters of the heating device;
• errors when designing a chimney: low vertical height, incorrectly selected cross-section, presence of horizontal or inclined sections, uneven walls;
• violation of tightness, narrowing of the channel due to soot, some kind of obstacle near the chimney;
• problems with the exhaust hood in the room, or with the general inflow;
• channel freezing.

Rollover traction

This is another possible phenomenon. When the flow of gases decreases, the draft in the channel also weakens. During this period of time, combustion slows down and the flame darkens. At the moment when circulation stops, a “thrust overturn” occurs. This is what is called a sudden release of smoke into a room. As a rule, it is one-time.

The reasons for the unusual situation are errors made during the construction of the device or chimney, the quality of the firewood and external factors: these include increased humidity, changes in atmospheric pressure, or the strength and direction of the wind. Such “tipping over whims” are typical for fireplaces with large, open fireboxes. These fumes may occur periodically, but they are not emergency events.

Strength check

Before you try to fight bad traction, make sure that your traction really leaves something to be desired.

You can check the traction using special devices or yourself. Simple ways to fix traction:

1. Light a piece of paper and let it burn for a while. When you bring it to the stove or fireplace, extinguish the paper and observe the direction of the smoke. If it is directed towards the pipe - good thrust, deviates in the opposite direction - reverse thrust, if it remains “straightforward” - there is no thrust. Similar manipulations can be done with thin tissue or toilet paper without setting it on fire.
2. If there are smokers in the house, then follow the direction of the cigarette smoke or the flame of a match or lighter near the fireplace or stove. Draw conclusions similar to the first point.
3. The flame of an ordinary candle can also help in determining the draft in the home.
4. A pocket mirror brought to the firebox and covered with condensation may indicate problems with removing smoke from the stove.
5. The presence of too much draft, which carries away useful heat from the room, is indicated by an audible hum in the stove - a loud hum.
6. The color of the fire in the firebox can be an indicator of different drafts. A golden hue means good draft, white flame means excessive draft, red color and black smoke means poor draft, high probability of reverse draft.

A regular lighter can help test traction

An anemometer is a device familiar to many people of the Soviet period. Using this device it was possible to measure the draft of the chimney. Readings within 10–20 Pa were considered normal. The disadvantages of the device are its low accuracy when the wind force is less than one meter per second.

This simple device will help protect your life in a stove-heated home.

Modern industry offers a sufficient number of devices for measuring draft; there are devices that record draft at the inlet and outlet of the chimney.

Making a deflector with your own hands

The sizes of the deflectors are different chimney pipes.
The walls of the upper cylinder take the wind pressure and direct the air around; smoke suction is achieved by sliding along the inner surface of individual jets. The deflector cannot be classified as a fan, since the device has a simple shape and does not have working mechanisms.

The contours of the parts that were calculated and plotted on the drawing are drawn on the cardboard and cut out. Using patterns, parts are transferred to metal with the addition of 1.5 - 2 cm along the edges of the lines for ease of assembly. Structural elements are obtained in expanded form after cutting with metal scissors.

A hacksaw is used to cut strips of metal or corners to connect parts into a finished product. The prepared parts are bent and rolled in accordance with the drawing. During assembly, the elements are superimposed on each other and connected with rivets.

Required Tools

During production, materials and tools are used that do not require professional skills from the master:

• rubber or wooden mallet;
• scissors and hacksaw for metal;
• ruler, tape measure;
• chalk for drawing lines on the metal surface;
• electric drill, rivet gun;
• metal drills;
• pencil and regular scissors.

The material is thin galvanized steel, a metal strip or a small section corner. The size of the rivets is selected in accordance with the diameter of the drill. Nuts and bolts are used for installation on the pipe.

Size calculation

A drawing is made on paper, which indicates the key dimensions for creating a pattern for a weather vane-draft amplifier for the chimney.

Ratio when calculating sizes:

• the deflector height is 1.7 d;
• the width of the cap is assumed to be 2 d;
• The diffuser width is taken to be 1.3 d.

The symbol d indicates the diameter of the chimney (internal). A different size ratio will result in poor efficiency.

Types of amplifiers

Deflectors are aerodynamic devices that specialize in deflecting air flow. With their help, you can adjust the traction force to the required parameters. The deflector fan works on a very simple principle: it sucks air from the atmosphere and directs it inside the chimney. The disadvantage of the device is its absolute helplessness during a quiet hike without wind.

The most common and effective deflectors are the designs of Grigorovich and Volpert. Modern improved deflectors are based on their prototypes. The most common designs are: round chimney nozzles (“Woppers”), star-shaped (“Shenards”) and H-shaped (multi-tiered). When choosing a deflector, carefully look at the material from which it is made. It should be stainless steel - a material that is durable and reliable.

Rotary flue turbines

Rotary turbines are mechanisms that are placed on top of smoke ducts. The principle of operation is similar to a fan, since they use wind energy to increase the pressure inside the pipe. Advantages of rotary turbines: they cover the chimney pipe and prevent the entry of precipitation. The device does not work in calm weather.

The most popular brands: Turbomax, Turbovent and Rotowent. Turbovent products are not suitable for installation on ducts for removing flue gases from furnaces.

It is also necessary to ensure that the temperature of the outgoing gas does not exceed a threshold of 250 degrees (these are standard requirements, which may differ for different models). Rotary pipes are installed for gas heating boilers.

Chimney weather vanes

Chimney weather vanes are a device for protecting the chimney on the leeward side. The model is characterized by good resistance to the negative effects of precipitation, a long service life and the presence of protective mechanisms for smoke exhaust. During the operation of weather vanes, one drawback was noted: they cannot cope with strong winds, and weather vanes also require careful maintenance - regular lubrication (especially in winter) and cleaning of soot and flue gases.

Smoke weather vane Duck and Dog – video review

The weather vane fan works on the principle of a stabilizer: it reduces the effect of strong wind on the draft in the chimney or enhances it in the absence of movement of gas masses in the atmosphere. The type of device in question is excellent for wood-burning fireplaces.

Chimney smoke exhausters

Smoke exhausters are electric heat-resistant fans for smoke exhaust. It is recommended to install these devices for adjusting the traction force only for narrow pipes. For its operation, access to an electrical network with a power of 220 V is required. Modern smoke exhausters have several upgrades, thanks to which the problems of reverse and weak draft are solved. The electric mechanism has no drawbacks; it works perfectly in calm and windy weather.

Caps and umbrellas are decorative elements for chimneys that do not solve the problem of low draft. After their installation, owners of heating devices noted additional problems: the formation of condensation on the surface of hoods and umbrellas, as a result of which the fan of the above devices quickly became unusable.

Thus, a wide variety of mechanisms for increasing traction cope well with the problem posed. The above models, in addition to smoke exhausters, have one drawback in common: they are too dependent on weather conditions. Therefore, to increase draft in the chimney, it is better to choose an electric smoke exhauster.

Manufacturing of devices to enhance traction

Principle of operation

A classic deflector consists of several parts:

1. cylinder
2. diffuser
3. an umbrella that protects the chimney from the penetration of debris and precipitation
4. ring bumpers that are mounted at the bottom of the device and around it

The device is installed on the chimney, which allows it to create an obstruction to the air flow. Thus, the wind is broken up into a huge number of small air currents that have very low intensity. This is necessary so that the wind flow captures the smoke that comes out of the smoke channel, which allows for increased draft. In addition, the deflector prevents the shock gas coming out of the pipe from entering back.

As experts note, if the chimney is incorrectly positioned on site, the deflector cannot operate at full capacity, so before installation, be sure to check the correct installation of the duct.

Also, the deflector can serve as a ventilation turbine, which is installed in systems with natural ventilation. Next, we will tell you in detail how to make a ventilation deflector with your own hands.

Deflectors for hoods

This is a fairly common option for forced ventilation. A deflector is an aerodynamic device that is installed above the chimney. It increases draft in the chimney due to changes in air flow. The essence of its work is the pressure drop when air flows around an obstacle, as well as the principle of changing air flows. It turns out that its shape allows you to increase draft in the chimney. Made of stainless steel, they are not afraid of corrosion, resistant to acids and high temperatures.

Note! Despite its simplicity and low cost, the deflector is ineffective in calm weather. The device does not operate from electricity or any other power source, but is completely dependent on wind load.

It cannot be called a full-fledged fan, since the deflector has a simple shape, without working mechanisms

But, there are types of smoke deflectors designed specifically for chimneys

It cannot be called a full-fledged fan, since the deflector has a simple shape, without working mechanisms. But, there are types of smoke deflectors designed specifically for chimneys.

Types of deflectors:

1. Wolpert deflector.
2. Grigorovich deflector.
3. Round or spherical deflector.

It is the round deflector that can create rotational movements under the influence of wind and remove smoke from the room. But, again, the disadvantage of the product is that it is ineffective in the absence of wind. The operating principle of this draft amplifier for ventilation pipes and chimneys is demonstrated in the video*

In addition, weather vanes, umbrellas and similar structures are often installed on chimney pipes. But they can't do everything that a high-temperature chimney fan can do. Let's look at how they work and what makes them special.

Features of chimney structures

Since smoke has a high temperature and constantly affects the structure, the chimney fan is made heat-resistant. The material can withstand temperatures up to 250 degrees. This is quite enough to serve faithfully for many years. Typically, the products are made of cast aluminum with a special coating. The motor has lifetime bearing lubrication and is also made heat-resistant.

As for the types of fans, it all comes down to differences in their shape and power. After all, chimneys are different, so you need to choose a device that would fit inside and have the shape of a chimney. These are the features of choosing products for the chimney. Usually the design is made in a square or round shape.

Which is better - a smoke exhauster or a blower?

When the traction turbine is integrated into the heat generator by the manufacturer, such questions do not arise. Adding an exhaust fan to a conventional direct combustion boiler is another matter. You must understand that in this case the smoke exhauster solves only one problem - creating a vacuum in the firebox and increasing draft. There are a number of negative points here:

1. Without an electronic control unit, performance will have to be adjusted manually. Automatic maintenance of coolant temperature is excluded.
2. When air is supplied through the open ash chamber door, the fan will force the boiler to operate at maximum. Setting up a long burn mode will not be easy.
3. In the event of an emergency stop of the impeller, fuel combustion will not stop, since gases pass freely through the volute or the body of the smoke exhauster. Air enters the firebox, increasing the likelihood of overheating.
4. The impeller and internal surfaces of the unit become covered with soot, which must be removed. The rate of sticking depends on the moisture content and resin content of the wood.

Blowing machines always work in conjunction with a controller, so the problems listed above do not exist:

• the blower changes performance and turns off at the command of the control unit, the coolant heats up to the set temperature;
• during the combustion process, the ash pan door is hermetically closed, air is supplied through a separate channel;
• when there is a power outage, the air channel is automatically closed by a gravity damper;
• the impeller blades do not come into contact with hot smoke and soot.

Now let’s compare the cost of a traction fan and a blower fan, not taking into account the price of the controller. A smoke exhauster for a TT boiler up to 30 kW will cost 90 USD. e., supercharger - 60-65 cu. e. The difference is due to the design features of the exhaust unit - hot gases should not overheat the electric motor, plus the impeller is made of metal (when pressurized, it is made of plastic).

Behind the mounting flange of the unit there is a small impeller designed to cool the electric motor

The installation complexity of the units is approximately the same. Installation of the discharge volute involves cutting out an opening in the ash pan door, and the smoke exhauster involves disassembling or cutting out the pipe. It is easier to install a roof hood, but you will have to pull a long cable.

How to make an exhaust unit

The main difficulty in assembling a smoke exhauster with your own hands is making a balanced impeller; the remaining parts are not difficult for a home craftsman who knows how to weld. If the impeller blades vary in weight, normal fan noise will turn into rumble due to vibration.

In addition to the blades, you will need the following elements:

• electric motor with a power of up to 150 W, maximum shaft speed – 1400 rpm;
• snail or homemade box shown in the drawing;
• a shaft with ventilation holes or an additional cooling impeller;
• studs with M8 nuts and other fasteners;
• power cable.

Types of deflectors

There are several types of deflectors. They differ from each other in shape and number of parts. At the same time, you can choose the materials that are used to create them to your taste. It could be:

1. Copper
2. Cink Steel
3. Stainless steel

Their shape can be very diverse: from cylindrical to round. The upper part of the deflector structure may have a cone-shaped umbrella or a gable roof. The device can also be equipped with various decorative elements, for example, a weather vane.

Let's take a closer look at several varieties:

TsAGI deflector

A structure whose parts are connected by flange or other means. This device is made from stainless steel, less often from galvanized steel. Its feature is its cylindrical shape.

Round volper

Its shape resembles the TsAGI deflector, but its main difference is the upper part. This device is most often installed on chimneys in small extensions, for example, in bathhouses.

Grigorovich deflector

If the site is located in an area with low winds, then such a device will provide excellent traction for many years. Experts call it a modified version of the TsAGI deflector.

Disc Astato

This type of device is distinguished by its simplicity and efficiency. This open-type deflector is made of galvanized or stainless steel, which improves traction efficiency in any wind direction.

H-shaped deflector

Its design is particularly reliable, since the deflector is made of stainless steel, and all parts are connected using the flange method. It can be installed in areas with any wind direction.

Weather vane deflector

This version of the device is the most popular and widespread. It has a rotating body on which a small weather vane is attached. The construction is made from stainless steel.

Rotating deflector

This device allows for maximum protection of the channel from clogging with debris and precipitation. Rotation occurs in one direction only. It is worth noting that it is necessary to monitor its condition, since in case of icing, as well as in calm conditions, the deflector will not work. Therefore, many people install it on gas boilers. It is also used as a rotary turbine, which is necessary for ventilation of residential and office spaces.

In addition, there is a Khanzhonkov deflector. However, it is currently not used, since more modified models of devices can be found on the market.

Reviews of popular fans

To focus on specific models, let's look at the MMOTORS line of fans, which are very popular. These are Bulgarian products with many advantages.

MMOTORS JSC BO VO 90/25 T (+150°C)

An excellent round shaped fan used for intermittent or long-term operation. Its productivity is 60 m3/h, with a power of 16 W. The product has a protection class of IP44. The seat diameter is 9.9 cm, and the depth is 2.5 cm. The fan produces 2.5 thousand revolutions. The product can be installed in channels with a short length. Thanks to the low-noise electric motor, which has double-encapsulated ball bearings, the device can operate for as long as 30 thousand hours. In this case, the fan can be mounted both vertically and horizontally. The body is made of aluminum alloy, which cools quickly and can withstand temperatures up to 150 degrees. Warranty – 3 years. The cost is about $38.

MMOTORS JSC BA VA 9/2 T (+150)

Unlike the previous version, the fan has a square shape; as for the parameters, they are practically no different. Power is the same 16 W, performance, protection class, speed and other indicators are the same. But the mounting diameter is 9.3x9.3, with a depth of 2.5 cm. Warranty - 3 years, cost - $38.5.

MMotors VOK 150/120 (+150°C)

The fan is also used for a round chimney. It is much more powerful than previous options. With a power of 18 W, the device has a productivity of 240 m3/h. Bore diameter – 12 cm. Protection class IP44.

The model has a different cross-section along the fan axis, which allows it to be adapted to conventional air ducts. The material is heat-resistant, and the engine will last 30 thousand hours of operation. Manufacturer's warranty – 3 years. Cost – $90. By purchasing such an exhaust fan for a chimney pipe, you can forget about weak draft.