Furnace extract. Forced exhaust for the chimney. How to make a deflector

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One of the most important conditions for the full functioning of the stove or fireplace, as well as the normal removal of combustion products from the room, is the presence of good draft in the chimney. It occurs due to the difference in temperature inside and outside the pipe, as well as different pressure indicators indoors and outdoors. Warm air has a lower specific mass (or density) than cold air, so the pressure will be lower (P=γgh, where γ is the density, g is the free fall acceleration, h is the height). Due to the pressure difference, warm air is displaced by cold air upwards, that is, with a decrease in the temperature outside, an improvement in draft in the chimney is observed. Accordingly, in the summer, traction will be the weakest.

To calculate the draft in the chimney, the following formula is used:

Hc \u003d Hd * (ρv-ρg) (mm water st), where

Hc - chimney draft;

If the chimney does not work well, first of all, you need to make sure of:

the absence of errors made when calculating the overall dimensions of the pipe (the diameter was incorrectly selected, recommendations regarding the height and location of the pipe were not followed, an erroneously selected section);
there are no deviations from the existing requirements for the arrangement of chimneys (there should be no ledges and narrowing of the section, the outer surface should not be absolutely smooth, the pipe should not be retracted by more than a meter, and the angle of the outlet should be equal to 30 degrees, the chimney should be protected from atmospheric precipitation with a special tip);
correct installation of the chimney elements (the design must be airtight);
absence of clogged sections of the pipe;
the correct choice of material for the construction of the chimney;
the absence of excessively cold air in the pipe;
lack of gusty wind and precipitation;
higher temperature in the house in relation to the street.

After receiving information on each of the above points, it is quite easy to identify the cause of the malfunctioning of the chimney, and understand how to increase the draft in the chimney.

Another manifestation of the poor performance of the chimney is the overturning of the draft, however, this phenomenon, unlike reverse draft, is of a short-term nature. In other words, during the firebox, smoke suddenly enters the room, after which the draft is restored again.

Thrust tipping can be caused by:

ordinary clogging of the chimney;
depressurization of the structure;
the ingress of precipitation into the pipe;
low atmospheric pressure outside.

How to adjust the draft in the chimney?

If you are looking for a way to improve the draft in the chimney, then the best option would be to purchase a draft regulator that automatically maintains the pressure in the pipe in the range from 10 to 35 Pa. A characteristic feature of this device is the possibility of not only increasing, but also reducing thrust. In other words, it allows traction control, thereby optimizing the operation of the entire heating system.

You can also improve traction by building up the chimney. If necessary, its height may slightly exceed the recommended normative documentation, but you should not overstep reasonable limits. If the pipe is too long, then the removal of smoke can become even more complicated, and it will be extremely difficult to clean such a pipe, except to use it.

How to increase chimney draft without making changes to its design:

Install rotary turbines on the head of the pipe, powered by wind energy. It must be borne in mind that the installation of turbines is possible only if the gas temperature at the outlet of the chimney does not exceed 200 degrees. In this regard, this chimney draft booster should be used primarily for gas boilers.
Equip the top of the chimney with a weather vane, which, due to its design, will always turn against the wind, thus closing the mouth of the chimney from blowing air and getting precipitation into it. Weathercocks show the greatest efficiency when installed on chimneys from wood-burning fireplaces (read the article: "").
Arrange a chimney with forced draft provided by smoke fans or smoke exhausters. The design of these devices includes an electric motor with a fan. If the wind is strong, then the increase in thrust is provided by wind energy, otherwise the fan turns on. Such devices are most often mounted on a small cross section.

How does the damper affect the operation of the heating system?

A damper (or gate) is often installed in order to prevent the appearance, as well as to protect the house from fire. Its installation can be carried out both directly in the chimney, and in the oven door (or the oven itself). The damper acts as a mechanical chimney draft regulator: if it is closed, the cross-sectional area of the pipe will decrease, as a result of which the draft will also weaken. In turn, when the damper is open, the cross section increases, and traction increases.

After all the fuel in the stove or fireplace has burned out, it is recommended to close the gate, which will reduce heat loss. The heating device will cool down more slowly, and the room will remain warm for a long time (read: "").

How to make a deflector, detailed video instruction:

What is a traction stabilizer for?

To maintain optimal draft, it is recommended to use a secondary air supply device called a chimney draft stabilizer or breaker. The presence of a safety valve in this device avoids the occurrence of excess pressure.

You can prevent problems with draft in the chimney by adhering to a few simple rules:

to eliminate cold air from the pipe, several newspaper spreads should be burned before kindling. The air will warm up slightly, and when kindling firewood, there will be no back draft;
it is necessary to clean the chimney at least twice during the heating period. Most often, the cause of poor draft lies precisely in the clogging of the chimney, and if it is regularly cleaned, then in most cases draft problems can be avoided. At the same time, the worse the quality of the fuel used (raw firewood, “smoke” coal, etc.), the more often it will have to be produced.

When a stove, fireplace or boiler is operating, most owners of private houses and cottages note a significant deterioration in the combustion process.

Most often this is caused by a change in traction parameters. To improve the quality characteristics, you should install a chimney draft booster, which, due to the simplicity of the design, can be done independently.

Causes of traction deterioration

First you need to determine the cause of the deterioration in traction. Therefore, first of all, the general condition of the chimney and all related elements of the system is checked.

This is done very easily. First, the entire heating system is completely turned off, after which the amount of soot is measured in the chimney using a long probe. This value should not exceed 2 mm.

The causes of insufficient draft in the chimney are conventionally divided into 2 groups: external factors and design features.

Among the design features:

the use of tees, elbows along the flue channel, bypassing obstacles that create aerodynamic resistance;
incorrect installation and adjustment of the damper;
incorrect height and diameter of the chimney that does not meet the requirements of manufacturers of heating or water heating boilers.

External factors include:

placement of the traction outlet below the roof ridge, which under certain conditions can lead to a traction “overturning”;
the presence of large objects near the chimney that form an area of \u200b\u200bhigh pressure or, conversely, rarefaction;
the predominance of strong winds in the region or vice versa calm,

All this can have a significant impact on the traction force and create additional resistance, thereby reducing its level. To avoid this, certain steps must be taken to increase or stabilize the draft so that the stove or boiler works more efficiently.

Methods and devices

For the normal functioning of the chimney, the upward flow must have a pressure of about 10-20 Pa. Anemometers are used to determine the level of thrust, and based on their readings and the results of fuel burnout, a decision is made - to increase or decrease thrust.

There are various options for how to bring traction in line with standards:

chimney extension;
the use of special devices;
the use of electric smoke exhausters;
traction stabilizers.

Chimney extension

The easiest way to eliminate low draft is to lengthen the chimney pipe. By increasing the difference between the levels of the chimney outlet and the boiler, the pressure difference of the upward flow also increases. For a flue pipe, the most suitable height is 5-6 meters, subject to the minimum distance between the vertical section of the chimney and the stove or boiler, and the absence of all kinds of bends, narrowings and deviations of the shafts.

If there is a high roof or large objects nearby that significantly impair traction, this method makes it possible to achieve the best result. However, with a very high chimney, the draft level can greatly exceed the required value, as a result of which the bulk of the heat will be released into the environment, and not spent on space heating. To prevent such a situation, special dampers are used, through which they reduce the volume of exhaust gas.

Deflectors

A deflector is a device that allows you to optimize air flow to increase draft in a chimney or air duct. The deflector is translated as a guiding device, a reflector. The name, in principle, fully describes its purpose and functionality.

The simpler the design, the greater the efficiency, since the currents reflected from the roof and side wind increase the traction force and suck the smoke from the chimney. The deflector, even with a heavy wind, eliminates the overturning of thrust, but in calm it is ineffective. The model of the chimney draft amplifier should be selected not only according to the size of the smoke exhaust duct, but also according to the expected wind load.

If you have a desire, a sheet of galvanized iron, a minimum set of tools, improvised materials, and even minor skills in working with metal, you can make such a device yourself.

To make the device you will need:

square;
roulette;
metal scissors or grinder;
wooden hammer;
riveter;
manual electric drill;
set of drills;
drill-end self-tapping screws with a press washer 15 mm;
tin or galvanized 0.3-0.5 mm;
improvised material for fastenings.

After carrying out the calculations and applying the contours of the parts to the metal, we perform the following:

cut out all the necessary details;
roll up the body of the nozzle and fasten the edges with self-tapping screws or rivets;
assemble and connect both cones of the device;
before assembling the umbrella, you need to install studs in the lower cone to fasten it to the common body, and if the installation is carried out on the legs, they can be fixed on the outside with rivets.

It is worth remembering that all connections of the draft booster in the chimney must be strong, as it can be exposed to strong winds. The video fully shows the process of creating a deflector with your own hands.

Such chimney draft boosters not only tolerate flue gases and high temperatures well, but also have corrosion resistance and durability.

Vane

The weather vane is another draft booster with a rather simple design without extending the flue pipe, and also dependent on the strength of the wind. However, this device, unlike the one described above, creates practically no resistance in calm. A small wing is installed on the head, which protects the edge of the chimney from the wind from only one edge.

Thanks to the auxiliary blade, and its placement opposite the place where the weather vane is fixed on the chimney, the device always closes the mouth from air flows that, flowing around it, create a vacuum at the outlet, thereby significantly increasing traction. Manufacturers advise the use of such devices for chimneys of wood-burning fireplaces in case of insufficient or unstable draft, in case of strong winds or when air vortices form above the flue duct due to unfavorable chimney position.

Rotary turbines

A rotary turbine is a mechanical device that uses wind energy to increase draft in a chimney. The turbine nozzle, regardless of the direction of the wind, rotates in one direction all the time, creating a rarefaction above the smoke channel, which contributes to an increase in thrust.

The design of such a draft booster allows you to protect the chimney from debris, leaves, precipitation and other things. The peculiarity of the turbine is that it does not work in calm weather, in the non-heating season air is removed from the smoke channel, and in the presence of wind a high rarefaction and an increase in thrust are created.

It is not recommended to install such draft boosters on the chimneys of coal-fired stoves and wood-burning fireplaces. It is worth considering that the flue gas temperature should not exceed 150-250˚C. Such a device is effective for natural ventilation systems and flue pipes of gas-fired heating boilers.

Electric smoke exhausters

In some cases, for example when using wood-burning stoves or fireplaces, it is permissible to install special electric smoke exhausters. These devices are designed for use in conditions of elevated temperatures, the presence of ash, condensate and other combustion products. However, it is strictly forbidden to mount them on the flue pipes of solid fuel boilers, in which the gas temperature can reach 650-800˚C.

Chimney draft is a natural aerodynamic process of air movement from a zone of high air pressure to a zone of low air pressure through the chimney ventilation channel.

Thanks to the presence of this phenomenon, humanity has been creating various technical devices for the efficient combustion of various types of fuel for several thousand years and to this day: stoves, fireplaces, boilers. And the quality of combustion is better, the more adequate the draft in the chimney will be.

By learning how to regulate and manage traction, you can improve the quality of heating your own home and reduce its costs.

From the foregoing, it follows that the chimney is a full-fledged, constantly working air conductor in the dwelling, and in some undesirable cases, even from it, regardless of the heating season. And everyone who cares about the quality of his own life will not neglect the banal draft in the chimney.

Factors affecting traction

Any factors that affect the density of the air inside and outside the home will affect the draft in the chimney. They can be conditionally divided into three groups.

Factors inside the dwelling - the material from which the house is built (natural - breathes, artificial - does not breathe), the average temperature in the house, the volume of the entire living air space interacting with the blower of the heating device, the number of permanent residents, the presence of additional sources of oxygen consuming inside the dwelling - stoves, heaters, method and regularity of airing and ventilation of the room.

The presence of draft in the chimney can be determined by holding a thin piece of paper (ordinary toilet paper will do for this). If he deviated, then there is traction.
For safety, it is better to bring a freshly extinguished match, and in the direction of the haze from it, you will find out in which direction the draft of your chimney is directed.

Visual methods for determining draft in a chimney

You can check the presence of traction by simply carefully observing the heating unit:

Smoke in the room indicates the presence of reverse thrust.
The flame has a pronounced white tint or noise coming from the chimney. This indicates too much traction.
If there is a dark red color in the flame, then this traction is not enough.
The fire is golden, sometimes yellow - a wonderful sign. Draft in the chimney is what you need.

Why is the chimney not working properly?

If it turns out that there is no traction or it is bad, then you need to try to figure out why this happened.

1. The most difficult situation is a poorly designed chimney (incorrectly selected section, pipe diameter or chimney height incorrectly calculated). If an inexperienced person undertakes to make a chimney with his own hands, then he often makes fatal mistakes. If the reason is in the wrong project, then the only thing that can be done is to completely rebuild the smoke exhaust system.

2. Another answer to the question why there is no draft is a carelessly mounted chimney (leaky joints). In this case, you can fix the problem yourself.

3. Perhaps the chimney is clogged and just needs to be cleaned. To do this, you can invite a specialist or do the cleaning work yourself. Maybe there is a “draught” in the room, and because of these air flows, the chimney is disrupted.

Reverse thrust

And why does reverse thrust occur and what to do when it occurs? Reverse draft - incorrect operation of the heating device system and the chimney as a whole. The definition of "reverse thrust" speaks for itself: "spent" fuel in the form of smoke is returned back to the room, instead of escaping into the atmosphere.

The causes of reverse draft in the chimney can be very different, ranging from design to the materials from which the chimney is mounted. The main points that must be checked if the chimney does not work properly.

Calculation error overall dimensions of the chimney:
- the cross-sectional shape of the chimney is chosen incorrectly;
- an error in the calculations of the cross section leads to an incorrectly selected diameter of the chimney pipe;
- the height of the pipe is calculated incorrectly (the recommendations of the building codes regarding the height and location of the chimney are not followed).
Deviations from the requirements to the device of chimneys:
- there should be no ledges and narrowing of the section;
- absolute smooth outer surface of the chimney;
- it is allowed to divert pipes no more than a meter, if necessary, then at an angle of 30 °;
- the chimney is not protected from the weather by a special tip (does not apply to chimneys intended for gas boilers).
Incorrect installation chimney elements:
- Structural leaks.
Unsuitable building material for chimneys.
Clogging of some sections of the pipe.
Very cold air in the pipe before starting the heating device.
Bad weather on the street, gusty wind, precipitation.
Outdoor temperature is higher than indoor temperature.

Try to adapt all the reasons above to your situation and you will definitely understand why there is no necessary draft in the chimney.

Overturning draft in the chimney

Thrust overturning is short-lived. For a short period of time, the "spent" fuel is drawn back into the room, then the thrust is restored. Provided that initially this was not the case in the operation of the chimney, we can assume the reasons for the occurrence of reverse draft in the chimney.

Common clogging of the chimney pipe.
There was a depressurization of the structure.
Bad weather broke out outside the window, possibly rainfall at the mouth of the chimney.
Low atmospheric pressure outside.

Ways to control draft in the chimney

If the test showed that the traction force is insufficient, action must be taken. The chimney draft regulator will help to vary the draft. Moreover, the device will do this automatically, maintaining the optimum pressure in the pipe from 10 Pa to 35 Pa. If necessary, the device can both increase the draft in the chimney and reduce it. So, this device will always keep the draft under control, which will ensure optimal operation of the entire heating system.

An increase in draft in the chimney can be achieved by building up the chimney pipe. The height of the pipe may be greater than prescribed in the regulatory documentation, but everything should be within reasonable limits.

Please note that the pipe should not be made too long, this will only make it difficult for the “spent” fuel to exit, and it will be much more difficult to clean such a pipe.

How to increase draft in the chimney without resorting to design changes:

Now you know how to increase chimney draft using mechanical devices.

Be careful, the installation of mechanical devices must be considered individually for each heating unit.

The role of the damper in the operation of the heating system

The damper, or chimney damper, protects the house from fire and prevents the possibility of reverse draft.

It is mounted:

in the door of the stove (fireplace) or is located in the stove (fireplace);
directly into the chimney.

The chimney damper acts as a chimney draft regulator. By closing the damper, we reduce the cross-sectional area of the chimney, respectively, the draft decreases. We open the damper, the cross section increases, and the chimney draft too.

After the fuel has burned out in the heating device, you can close the gate, thereby reducing heat losses. The stove or fireplace will not cool down as quickly, which will save on fuel.

What is a traction stabilizer

A chimney draft stabilizer, or breaker, is a secondary air supply device in doses that allows you to maintain optimal draft. The breaker has a safety valve that prevents overpressure.

Using the following tips, you can avoid problems with draft in the chimney:

If there is cold air in the chimney, then before ignition it is worth burn a couple of spreads of newspapers. The cold air will heat up, become warm enough, and when the heating device is ignited, there will be no back draft.
Chimney needs to be cleaned at least twice during the heating period (see How to clean the chimney). If you neglect the rules for operating the chimney, it can simply become clogged. It is because of this that the draft force in the chimney may decrease, and there is also the possibility of reverse draft in the chimney.

Now you can easily deal with problems in the operation of your heating system.

If you have a fireplace or a stove in your country house or country house, then you know exactly what a chimney is. But at the same time, many do not know that during the operation of the chimney, one of the most common problems is the draft of the chimney. Let's now talk about how you can check traction.

Chimney draft check

You'll need : anemometer, sheet of paper, mirror, metal ball.

It is best to check the draft in the chimney with an anemometer designed specifically for this purpose. Thanks to this device, you can get the most accurate data, but on condition that the air speed is 1 m / s. To date, there are more advanced devices that allow you to measure the draft in the chimney with Pascals, even taking into account the fact that pressure can be different in different parts of the chimney.
To check the draft, you can also bring a sheet of toilet paper to the chimney. In this case, the thrust force is set as it deviates, that is, the greater the deviation, the stronger the thrust. But its sufficiency is determined visually. If smoke is observed in the room, then this tells us about reverse thrust. And the flame of bright white color with a strong noise can speak to us about its strength. But if dark stripes of red color appear on the fire, then there is not enough thrust. When the flame in the boiler is golden yellow in color, then the draft in the chimney is more than enough. The direction of the draft can also be determined from the smoke from the cigarette.
You can also check with a small mirror, which must be installed in the smoke hood in place of the draft sensor. We turn the mirror side towards the flue gas outlet channel. In case of problems with smoke removal, gases will get on the mirror, in connection with which it will fog up.
For the next method, we need a metal ball with a diameter of 100 mm. To check the chimney for clogging, it is necessary to lower it to the entire length of the channel. In cases where, to the very bottom, he does not meet any obstacles on his way, then there are no blockages.

So what is traction? This, in scientific terms, is an aerodynamic directed air flow of flue gases in any exhaust structure. This phenomenon occurs due to the fact that the wind is also a matter of the difference in air pressure inside the furnace and outside, air masses always tend to where there is the least resistance. And in simple words, the reverse draft in the chimney is when the air flow of gases leaves the burning wood not into the chimney outside, but back into the room. There is also the term "thrust overturning" - and this is when the direction of the air flow for a short time changes to the opposite.

You will be surprised, but tall buildings or trees standing nearby, and if the height of the chimney is below the roof ridge, can lead to draft problems. There are many factors, so let's figure out together why exactly you have such a problem and how to improve chimney draft once and for all.

How to understand if there is a reverse thrust?

It is easy to notice the first signs of problematic draft - if the firewood in your stove burns with a lot of smoke, the glass on the door instantly smokes and when you open the door the smoke immediately falls into the rest room - the draft is too weak. And if you do not figure out how to increase the draft in the chimney, it will soon become not only bad, but also reverse.

You can check the draft force in the chimney in the following simple ways:

Toilet paper - exactly how it is deflected.
Direction of smoke from a cigarette.
The appearance of smoke in the room is already a reverse thrust.
The hum in the chimney and the white color of the flame - the draft is already too much.
The yellow-golden color of the flame is good traction.

In Soviet times, there was even a special device for measuring the draft in the chimney - an anemometer. According to it, certain objective data were obtained if the wind speed was more than one meter per second. Today, more modern devices are already being used that measure the draft of the chimney in units of pressure - which one is at the base of the chimney, and which one is at the top. They cost a lot, but if you can’t solve the problem with traction, it’s better to buy.

Why does this effect occur?

Where does it come from and who is to blame? Well, the most common cause is an error in the design of the chimney. Further, no less popular "culprits" are debris in the chimney, strong air currents in the pipe, and even a certain influence of atmospheric phenomena.

Reason #1 - Chimney Design

First of all, the design of the chimney itself matters - at too high a draft is always strong, and at a low one it is often insufficient. The optimal length is just over 5 meters, then problems with traction rarely occur and certainly not due to the height of the pipe.

Also, the cross-sectional area of the chimney must correspond to the furnace - with too small cross-sectional dimensions and at the same time with a powerful furnace, a large volume of combustion products simply cannot leave normally, sufficient traction is not created. As well as a disproportionately large chimney, it will lead to the fact that all the heat, as people like to say, "will fly out into the chimney." And in no case should pipes of different diameters be installed at the chimney in different areas - there will be soot and draft problems.

The uneven surface of the pipe also serves as a serious obstacle to the movement of smoke - any deposits reduce the diameter of the pipe, and it is more and more difficult to melt the furnace every time. Tilt angles with turns of the chimney also create their own difficulties - if soot constantly accumulates in the corners, it will also interfere with normal draft. To avoid this, when designing, adhere to standard norms - 45 ° bend, 90 ° turn.

The very shape of the smoke hole is also important: round is the most favorable for good traction, but with square and rectangular, problems often arise. So, in these corners, there is an additional twist at the corners, which slightly interferes with the overall flow and in total reduces traction.

By the way, the most common problem of poor draft is with metal chimneys. Their trouble is that they quickly heat up, but also quickly cool down, and cold air always sinks down. Good old brick chimneys are more reliable in this regard.

Reason # 2 - violation of ventilation

Also, the lack of ventilation in the room where the stove is heated can lead to such a misfortune. Check for drafts - are they too strong? Such whirlwinds right in the room can "confuse" the direction of the smoke, no matter how strange it may sound. By the way, intense air currents in the baths often arise because of the stairs to the second floor. Follow this, and never open windows on the landing, if it is much higher than the level of the firebox.

Also pay attention to ventilation if you have a geyser in the boiler room. It will still draw air from the combustion room, over time a serious lack of oxygen will form and a critical air rarefaction will occur. From time to time, a stream of air will rush through the chimney, the column will go out, and the room will smoke. Do you have such a situation? Are there still deaf-tight plastic windows? Urgently deal with the issue of ventilation.

Reason #3 - external factors

Smoke can also get into the room due to high humidity on the street or strong wind. Or when the street is already clearly warmer than in the house - all the same pressure difference. If you have a reason for this, you will certainly hear an unpleasant smell of burning. Just open the window then and ventilate well, let the temperatures even out a bit.

And very rarely, but it happens that the reason why there is no normal draft in the chimney is the wind, which causes turbulence above the roof - if nearby buildings are located in a special way and there are too branched trees nearby. Or the head is incorrectly directed in relation to the roof ridge - and this happens.

An important condition for the full functioning of the furnace is normal draft, which will help to remove combustion products. This indicator is strongly influenced by the diameter of the chimney. If it is of a small cross section, then the products of combustion will not be able to go outside and will begin to accumulate inside the housing. In the case of using a wide chimney, cold air flows will not allow burnt substances to rise. All these and other nuances can be compensated by a traction booster, which can really be done independently.

Traction enhancement options

There are several types of devices that can increase the outgoing air flow. Among them, the most popular are:

Deflector . Structurally, it increases the diameter of the chimney at the outlet.
. A device that is installed on the top of the chimney (turns against the wind), protecting its mouth from dust and protecting it from various precipitation.
Smoke fans . Most often they are installed on a fireplace chimney with a small cross section. They can be turned on when there is not enough natural wind flow.
Rotary turbines . Such devices are installed on the head of the pipe to provide free access to the wind. They are best applicable for gas boilers.

But the simplest and no less effective is to extend the chimney pipe. This increases the difference in air pressure and increases thrust. Typically, the chimney goes up to a height of 5 meters (this distance includes the vertical section of the chimney, excluding bends, slopes and narrowings).

If the roof has a sharp slope or large objects are located near it, then these circumstances worsen the draft, which will help overcome the increase in the length of the chimney. But with a very long pipe, there may be heat losses, which will go not to heat the home, but to heat the cold street air. To prevent this from happening, special dampers are provided in the furnace that regulate the amount of exhaust gas.

Do-it-yourself deflector installation

The device optimizes air removal, being a reflective device. It will not be difficult to do it yourself - just arm yourself with the necessary tools and purchase sheets of galvanized metal. Their thickness should be no more than 1 mm.

The simpler the design of the deflector, the more accurate the drawings will be and the more efficient the device. You don't need to come up with an intricate shape. For example, the most elementary scheme is taken. Dimension D is the diameter of the pipe with a small gap so that the deflector can be securely fixed on it. Di - twice the cross section of the chimney.

Required tools:

roulette;
electric drill;
clamps;
hammer;
square;
metal scissors, hacksaw or grinder;
riveter;
heat-resistant mastic;
self-tapping screws;
fastening parts.

After preparing the tool, you can start working:

Apply the dimensions of the workpieces to the sheet of metal. Cut them out.
Roll the future body of the nozzle into a ring and fasten its edges with rivets or self-tapping screws.
Assemble the chimney cone in the same way.
Combine both items. For better sealing, treat their joints with mastic.
Build a metal umbrella and fasten it on top of the deflector with studs or rivets if it is made on the legs.
Strengthen the stability of the structure by applying clamps.

The result should be a durable traction booster that can withstand wind and precipitation.

Wind vane to increase traction

This amplifier, unlike the previous one, can rotate around the chimney. The principle of operation of the device lies in its response to air currents, as a result of which the traction amplifier takes the appropriate direction from any breath of wind. Air is blown into special gratings, which creates a constant vacuum in the pipe.

The demonstrated product can work in any weather conditions. It reacts even to the slightest breeze. The invented device improves the efficiency of the combustion boiler by about 20%. If you install it on a pipe, then you will not need to make the chimney very long, you can shorten its visible part above the roof.

The weather vane is an exhaust product for the ventilation system, therefore it can be used for multi-apartment and private houses. He gained particular popularity when installing gas boilers. The device not only enhances traction, but also prevents the attenuation of the boiler.

Electric fans

Powerful fans that are used for fireplaces and wood-burning stoves. They are designed to work in a hot environment, where there is a lot of ash and other combustion products.

The body of such devices is made of galvanized steel with a specially applied polymer coating, which provides it with protection from aggressive environments. It has a protective grill that prevents various large and medium-sized objects from entering the air duct.

The ventilation device is powered by a single-phase motor, which can ensure uninterrupted operation of the system in any weather. Although it has protection from the flow of hot air, it is placed outside the zone of its movement for safety reasons. It has ventilation holes and a special wheel that prevents soot and dust from sticking.

Such a ventilated system is fully automated. It has built-in temperature sensors, as well as their counterparts that regulate the strength of the air flow. They are triggered by deviations in the operation of the electric motor and create the optimal traction of the device.

Their principle of operation is similar to the deflector - they are also located at the top of the pipe and use wind energy. The nozzle, on which the grids with wings are located, rotates in one direction, regardless of the direction of the wind. Due to its movement, it creates the necessary air rarefaction. The design of the device resembles a dome and is able to protect the chimney from debris and precipitation. It is designed for gas boilers and ventilation ducts. Not recommended for solid fuel boilers and fireplaces.

In calm weather, this amplifier does not work, but in the summer, when the boiler is not functioning, it can create a very strong draft, which is often superfluous.

Description and scheme of operation of the traction amplifier (video)

In the next video, experts will talk about the amplifier, as well as the scheme of its operation. At the same time, they will indicate the advantages of this method of removing combustion products.

Which of the proposed devices to choose will help to decide the very design of the chimney channel and the type of boiler that heats the home. They can be resorted to if it is impossible to increase the length of the pipe.

The key factor influencing the efficiency of the boiler is the draft in the chimney. With its increase for solid fuel boilers, the burning of coal or firewood improves, which increases the efficiency of the installation. For gas boilers, the draft must be rigidly stabilized in order to ensure normal combustion and not blow out the flame. When building a chimney, especially when it is not possible to use the most optimal route, it becomes necessary to use a chimney draft booster. What can affect traction, and how to implement it, we will consider further.

Installing a boiler for solid, liquid or gaseous fuels, a stove or a fireplace without fail implies the arrangement of a chimney system. The main parameters of the chimney are the draft level and the volume of exhaust gases. Structurally, it is an isolated channel, a pipe laid from the outlet of the furnace to the external environment outside the building. The draft is created due to the difference in pressure at the chimney inlet and outlet, which is caused by the temperature difference and the level difference between the inlet and outlet. The higher the chimney, the stronger the draft. The thicker the channel, the greater the volume of gases it is able to divert from the boiler.

However, there are a number of reasons why the draft in the chimney can decrease, or even “tip”, when air is sucked in from the outside into the chimney and combustion products enter directly into the room.

Causes of poor traction

Conventionally, two large groups can be distinguished: the design features of the chimney and external factors that affect the level of thrust.

Design features include things like:

The use of elbows, tees along the chimney, bypassing obstacles that create aerodynamic resistance.
The use of an incorrect chimney section and height that is different from the requirements of the boiler manufacturer.
Incorrect installation of the gate (flap) and its setting
The presence of a chimney head, umbrellas, spark arrester, etc.

External factors include:

The location of the chimney outlet is below the roof ridge, which, with a certain wind direction, can cause the draft to “overturn”.
The presence of dimensional objects near the chimney, a neighboring building or other structure that create a zone of rarefaction or, conversely, increased pressure in the chimney area.
The predominance of strong winds or, conversely, the dominance of calm weather.

All this affects the level of traction, often creating additional resistance and reducing it. In any case, it will be necessary to find an adequate way to increase the draft or stabilize it in order to ensure the most efficient operation of the boiler or furnace.

Methods and devices

During normal operation of the chimney, the upward flow pressure should be in the range of 10-20 Pa, which corresponds to the optimal flow of exhaust gases from the combustion chamber. To find out the real state of affairs, anemometers are used that can show the level of thrust. Based on the readings of the device and the result of fuel burnout, you can say for sure whether it is necessary to increase or decrease thrust, use stabilizers that will automatically maintain the ideal air flow rate in the channel.

There are many ways to increase traction or bring it into line with the standards and requirements of the boiler manufacturer:

Increasing the height of the chimney;
The use of deflectors, weathercocks, rotary turbines as a chimney head;
The use of smoke exhausters powered by electricity;
Traction stabilizers.

Increasing the height of the chimney

The easiest and most often reliable way to deal with low draft levels is to increase the height of the chimney. As a result of the increase in the level difference between the boiler and the chimney outlet, the pressure difference also increases, the upward flow of hot gases significantly increases the draft. The optimal height of the chimney is 5-6 meters, subject to the minimum distance between the boiler and the vertical part of the channel and the absence of various deviations, bends and thinning of the channel.

Calculation of the height of the chimney, depending on the location from the roof ridge

In case there are various external factors such as a high roof profile, ridge, nearby buildings or other objects that worsen the situation, this gives the best result. However, if the chimney is too high, the draft can significantly exceed the required threshold, from which most of the heat will simply go outside, heat the environment, and not the working fluid in the heating system. The fuel will burn out worse. To prevent this effect, dampers or draft stabilizers are used, with which you can reduce the volume of exhaust gases.

Deflectors

Special devices fixed on the chimney head. Their shape and design are chosen so that air flows directly near the chimney outlet do not interfere with the release of gases, but rather contribute to this. The deflector is based on Bernoulli's law. In the presence of air flows, they flow around the main part of the deflector and create a vacuum in the area directly above the chimney outlet. An excellent option for use in conjunction with solid fuel boilers, where an increase in traction ensures proper burning of coal and briquettes.

The deflector cannot be installed with gas boilers. A strong wind can significantly increase traction, as a result of which the burner flame can simply go out.

The effectiveness of deflectors directly depends on the presence of wind, therefore they are practically useless in calm weather and even create additional resistance.

Vane

Another means of increasing draft without increasing the height of the chimney and also dependent on the wind. However, unlike the deflector, the weather vane does not actually create resistance in calm weather. Its design is extremely simple. A small wing is attached to the chimney outlet, covering the head from the wind on one side.

With the help of an additional blade and its location on the other side of the chimney axis from the weather vane attachment, it is always turned so as to close the mouth from air flows. They flow around it and create a vacuum at the outlet, increasing traction.

Feedback from the owners of this device indicates unsuitability due to jamming of the rotating part with smoke deposits or freezing of precipitation.

Rotary turbines

A special design consisting of rounded blades located at a certain angle to the axis of rotation. The turbine, under the influence of outgoing gases and external flows, always rotates in the same direction, maintaining and enhancing thrust. The advantages and disadvantages are the same as for deflectors.

Electric smoke exhausters

In some situations, for example for use with wood-burning stoves or fireplaces, the installation of special electric duct fans-smoke exhausters is allowed. They are designed to work in an environment with elevated temperatures and the presence of ash, condensate and other combustion products. However, it is unacceptable to install them on the chimney of a solid fuel boiler, the temperature of the gases in it can reach 650-800 ° C.

Such smoke exhausters are able to automate the operation of the chimney. A special temperature and flow sensor regulates the activity of the electric drive, thereby always maintaining optimal traction in the system.

Traction stabilizers

A whole class of devices for automatic regulation of gas pressure. They are primarily designed to work in systems with obviously good or increased traction. Their task is to regulate the volume of flue gases removed, depending on the efficiency of the main chimney. In fact, they replace inefficient dampers that constantly require attention and manual adjustment.

The principle of operation of the stabilizers is based on mixing cold air from the room into the gases leaving the furnace. This reduces the temperature of the total mixture that enters the vertical channel and reduces the flow rate.

Structurally, this can be a device assembled on the basis of a chimney tee, which has an intake valve on the branch. The movable shutter, fixed on the free axis, opens only when the pressure in the system is exceeded, which is regulated by means of a counterweight weight.

How to determine the best option

The choice of a specific solution depends on the structural features of the chimney in each individual case. The use of elements such as deflectors, weathercocks, turbines or smoke exhausters is relevant only if there are certain factors, such as windy weather or the impossibility of arranging a full-fledged chimney in height.

The best solution, as always, is to increase the height of the chimney and use various stabilizers, which, in combination with increased draft, can ensure optimal operation of the boiler. In this case, the influence of external factors is reduced, and all possible barriers to creating a natural flow of combustion products are eliminated.