The presence of good draft in the chimney is an essential condition for the full functioning of the stove or fireplace (read also: " "). Draft is a directed air flow that occurs in an exhaust structure due to the difference in air pressure inside and outside it, while the air masses will always tend to where there is the least resistance. Accordingly, backdraft in a chimney is a phenomenon in which the flow of air with smoke from fuel burning in a stove does not go out through the chimney, but back into the room. If the direction of air flow is reversed for a short period of time, this is called thrust reversal.
Why is there no draft in the chimney? There can be a whole host of reasons for this, ranging from improper chimney design to nearby tall buildings or trees. If the draft is poor, firewood will emit a large amount of smoke when burning in the stove, the door will instantly smoke (this is especially noticeable if there is glass on the door), and when it is opened, smoke will pour into the room. In such cases, it is extremely important to identify the cause of insufficient traction as quickly as possible and try to eliminate it.
Checking the draft in the chimney can be done using a sheet toilet paper(you need to observe its deviation) or with the help of smoke from a cigarette (you need to monitor which direction it is moving). The appearance of smoke in the room during combustion indicates reverse draft, a yellow-golden flame indicates good draft, and the flame white and a hum in the chimney - about excessive draft. There are also more modern and accurate ways to check the draft in the chimney, for example, special measuring instruments, allowing you to determine the draft at the base of the chimney and at its exit. By analyzing the data obtained, it will be easier to determine what causes insufficient or reverse thrust.
The main causes of poor draft in a chimney
Most often, draft problems arise due to miscalculations made at the chimney design stage, because this is often done by people who have neither special education nor sufficient experience. In addition, clogging of the chimney pipe, strong air currents arising in it, as well as various atmospheric factors often lead to a violation of draft.
Reason one – errors in the design of the chimney. Poor draft in a chimney can be a consequence of a pipe that is too low, while a pipe that is too high, on the contrary, results in too strong a draft. The optimal height is considered to be slightly higher than 5 meters, in which case there should be no problems with traction. The cross-sectional area of the chimney pipe, which must correspond to the size of the stove, is also important. Thus, the combination of a narrow pipe with a powerful stove will lead to the fact that a large volume of smoke will not be able to escape normally and will begin to leak into the room. With a disproportionately large chimney, all the heat generated as a result of fuel combustion will literally fly out into the chimney. It is strictly not recommended to install pipes in different areas various diameters, since this will inevitably lead not only to problems with traction, but also to the excessively rapid formation of soot deposits. Soot, accumulating, will, in turn, reduce the diameter of the pipe, as a result of which the process of lighting the stove will become more complicated each time.
The draft force is also affected by the shape of the chimney opening: with a round draft the draft will be much better than with a square or rectangular one. The fact is that additional turbulences are formed in the corners, which create obstacles to the overall air flow, as a result of which a general decrease in thrust will be observed.
As for materials, the least likely to complain about the lack of draft in the chimney will be those whose chimney is made of brick, but with a metal chimney, problems with draft occur quite often. The fact is that the metal heats up quickly, but at the same time it cools down just as quickly, as a result of which the cold air falls down.
Reason two – violation of ventilation. Backdraft in the chimney can be caused either by a complete lack of ventilation in the firebox room, or, conversely, by strong drafts that seem to confuse the smoke, which changes the direction of its movement and begins to exit into the room.
Special attention It is worth paying attention to the issue of ventilation even if a gas water heater is used for heating. During operation, it will burn the air in the room, resulting in a serious lack of oxygen and the air becoming very rarefied. Because of this, a stream of air will periodically rush through the chimney, which will invariably lead to attenuation of the speaker and smoke in the room. The situation can be further complicated by the presence of sealed plastic windows, not allowing air from the street to pass through. In such a situation, it is imperative to ensure proper ventilation.
Reason three - external factors. If you cannot determine why there is backdraft in the chimney, pay attention to various atmospheric phenomena; it is quite possible that they were the cause of this problem. Problems with traction can be caused, for example, by high humidity or strong wind. A similar situation occurs when it is much warmer outside than in the house (in particular, this often happens in the spring). IN in this case You should simply open the window and ventilate the room well, allowing the temperatures to even out.
When trying to find out the reason why there is no draft in the chimney, you need to pay attention to the location of the chimney. It is best if it is located in the interior of the building, in which case it will be less affected by various external factors. If the chimney is built on the outside of the house, then in cold weather it will take longer to warm up, and the draft will be much worse. In addition, condensation will often form in it.
How to get rid of backdraft?
One of the ways to cope with backdraft is to use a deflector - a mechanical fan, the function of which is to suck smoke from the chimney pipe (read: " "). Another chimney draft regulator is a damper, which is a special damper. One damper is usually fixed in the chimney duct, and the second is either in the stove itself or in its door. Having tried various options their location, you can find the optimal one to solve the problem with traction.
How to make a draft regulator with your own hands, details in the video:
Sometimes backdraft can be temporary, occurring for several days. This may happen at the beginning heating season, when in damp autumn weather the stove is lit after a long period of inactivity. In this case, the cold air accumulated in the pipe acts as a chimney draft limiter, and smoke, instead of going out into the street, begins to fill the room. To solve the problem of temporary backdraft, you need to find out the cause of its occurrence and then eliminate it.
Our grandparents knew about the concept of reverse thrust. In almost every private house with a stove in winter, one could observe how men smoke near the firebox, and all the smoke goes into the stove, and not into the house. With the advent of modern gas heating equipment, the problem did not disappear. Very often there is backdraft in the chimney gas boiler or columns. To heating device did not deteriorate and functioned properly, it is necessary to become familiar with the nature of this phenomenon.
The occurrence of reverse thrust
Draft is the directional movement of air through a chimney or other channel. We know from school that such movement is caused by temperature differences or changes atmospheric pressure, since the density of warm air is less than cold air, and a phenomenon called draft arises, causing air currents to move.
If such a process is carried out without the help of additional devices or instruments, then it is called natural draft. When the air flows turn around and begin to move in the opposite direction, reverse draft occurs in the chimney. What to do in such situations depends on many conditions. First of all, it should be understood that vacuum occurs due to the presence of sources in the room natural ventilation. To avoid smoke in the room, it is useful to know exactly how much air comes out of the room, because the same amount should enter it. When the draft operates correctly, it can be easily controlled, reducing heating costs and increasing the quality of heating.
It's interesting that even with correct device chimney in a private house may experience a short-term reverse draft, called overturning. The reasons are most often unfavorable weather conditions, and the effect does not last long.
Definition of traction
At the beginning of each heating season, before starting the boiler or furnace, you should check whether there is a backdraft in the chimney. What should I do for this? Of course, there are special devices for measuring traction, but they are very expensive and are available only to specialists.
From the experience of generations it is known that the draft in the furnace should be checked using a flame. To do this, light a match and bring it to the firebox. If the flame draws into the stove, then the draft is good and you can begin to melt the room. When the fire does not move, there is no draft at all, but if the flame blows into the room, then the draft in the chimney is reversed. What to do when starting gas boilers? Open fire cannot be used in this case. You should check where the smoke is drawn by tilting a thin strip of paper.
The color of the burning flame can also tell about the amount of draft in the furnace. Ideally it should be golden. If the color is red, then the fire does not have enough oxygen for normal combustion, and if a hum occurs during the fire, it can be judged that there is excessive exhaust.
This process is influenced by a large number of factors. The main thing is the incorrect design of the chimney at the construction stage. In order not to encounter the problem of insufficient or incorrect traction in the future, it is necessary to correctly calculate in advance:
- chimney cross-section size;
- its location;
- material of manufacture;
- shape;
- pipe height;
- the presence of additional devices that increase traction performance.
The quality of air movement is also affected by the number of people or devices consuming oxygen in the room. The latter include air heaters, irons, stoves, and so on. Regular ventilation of the room is also important for proper operation.
A person can control all this independently, so the presence of reverse draft in the chimney depends only on him. What to do if cravings are affected weather conditions? It is impossible to control them, but it is quite possible to resist them.
The main reasons for adjusting air flows
From all of the above, it is clear that rarefaction of air is only a consequence of weather phenomena or human actions, therefore the elimination of backdraft in the chimney begins with precise definition the reasons for its occurrence. The main thing is the incorrect design of the entire heating system and smoke removal. In this matter, it is important to pay attention not only to calculations, but also to the selection of material. For the stove chimney it is better to use ceramics or bricks, but for boilers or geysers will become ideal metal pipes. In addition, the cause of backdraft in the stove chimney may be hidden:
- in a clogged chimney;
- there are narrow sections in the smoke passage channel;
- location of the chimney in the “wind surge” channel;
- in violation of natural ventilation;
- under adverse weather conditions.
By the way, the presence of correct air flows depends on the weather outside, even if all the rules for arranging a chimney are observed. Rollover occurs especially often in strong winds, high humidity air or high temperature outside the window. This is relevant when using a gas water heater in summer period.
In any case, if such a phenomenon occurs, it would not be superfluous to inspect the smoke exhaust routes and make sure they are in good working order.
Construction problems
The installation of a chimney in a private house always assumes the presence of a straight chimney located strictly vertically. This technique is considered to be the most effective, since if there are bends, inclined sections or horizontal pipes draft will deteriorate proportionally, and slowly passing smoke will accumulate a large amount of soot on inner surface ducts
You should also pay attention to the location of the chimney outer wall. This is very rare, since it involves slow heating of the smoke paths and a large accumulation of condensation during cooling, which easily freezes in severe frost. Taken together, these phenomena lead to frequent occurrence of reverse thrust.
The least resistance to moving smoke in the right direction occurs only if there is a round pipe. It is considered ideal for arranging the chimney of any heating device.
Correct installation
It is important to know that depending on the type of heating device being installed, the installation standards, as well as the connection rules, will change. Only with correct calculation can you get effective work heating system without creating rarefied air.
This is largely influenced by the combustion temperature of the fuel. The higher it is, the stronger the thrust will be, but at the same time the need for obtaining a sufficient volume of air for combustion will also increase proportionally. If ventilation does not provide it, then the stove or boiler will begin to take it out of the room, thereby provoking the occurrence of reverse draft.
To avoid this phenomenon, when operating the stove it is necessary to use a fireplace tooth in its design. The device is a small ledge between the firebox itself and the smoke collector. Reverse draft in the chimney of a gas water heater can be eliminated by installing a supply valve, but its operation does not always help to really solve the problem.
Materials for arranging a chimney
To avoid future problems with draft in the heating device, you should select in advance the right material for the arrangement of its chimney. Absolutely all gas boilers, water heaters and other devices should be installed metal chimneys. This material promotes rapid heating, but also equally rapid cooling.
For heating sources in the house that use solid fuel, the ideal chimney covering would be brick or ceramics. Such materials contribute to greater heating, but at the same time retain heat better.
When arranging smoke exhaust routes, it is important to pay attention to the smoothness of the surface. The smoother it is, the less likely it is that soot will quickly accumulate and require chimney cleaning.
Cleanliness check
To prevent backdrafts from occurring during the heating season, chimneys should be regularly checked for cleanliness even before the need to regularly use heating appliances. Blockages can be caused by birds flying into the chimney, large accumulations of soot, or peeling of plaster from the inner surface of the chimney ducts. You can check the cleanliness by looking into the pipe from the roof or through the cleaning hatch, but using a mirror.
If there are contaminants in the pipe, you can clean them using special brushes and even chemicals, sold everywhere today. To put off chimney cleaning as long as possible, it is recommended to use one of the preventive tips that have been passed down through generations.
The first states that aluminum cans should be burned in the stove every 10-12 fires. It is important that the combustion temperature is such that the cans burn completely in 5 minutes. It is also recommended that if there is a large amount of soot in the chimney, throw approximately half a bucket of peeled and chopped potatoes into the firebox while it is burning. The starch released during the combustion of the product can soften the plaque, and the soot itself will fall off the surface of the chimney. You can periodically burn rock salt in the firebox, this will also delay cleaning.
Chimney height
The presence of draft in it largely depends on the height of the pipe that removes smoke from the heating device. The chimney should be approximately 5 meters high, but not lower than the ventilation duct. Its top point should be 0.5 meters above the level of the roof ridge and approximately 1.5 meters away from it. In this case, you should take into account the presence of trees or other buildings around the house that may impair traction.
Natural process
In a private house, the presence of natural ventilation facilitates inflows fresh air into the room. In apartments, especially after renovations and replacement of windows, the room often becomes sealed, and in the absence of air flow, a vacuum is created. To ensure that the situation remains normal, during repairs you should think about installing additional ventilation valves. The usual kitchen hood or air conditioner.
Eliminating backdraft
So, how to get rid of backdraft in a chimney? In most cases, this problem can be solved on your own. To eliminate a short-term lack of draft in the furnace firebox, you should burn a couple of newspapers to warm up the air in the chimney, but more often than not, chimneys simply need cleaning. If the draft disappeared after the repair or did not appear at all, then an error was probably made in the calculations, and additional devices will need to be installed in the room.
These can be smoke exhausters, chimney weather vanes and fans or deflectors. It may be necessary to increase the length of the pipe. You can also briefly open the window to ventilate and bring fresh air into the room or insulate the chimney if its parts are located on an external wall.
The lack of traction is dangerous not only for the functioning of the devices, but also for the health of the residents themselves, therefore in such situations it is prohibited to use heating devices until the problems are resolved.
The directed movement of combustion products along the smoke exhaust paths is a fundamental factor for the efficient and safe operation of almost all heating devices. Movement occurs air masses in a chimney with a difference in pressure, temperature and density, between the air in the smoke exhaust duct and the atmosphere. Warm air in the chimney has a lower density and tends to rise, and its place is taken by colder air masses.
But there is such a thing as. The manifestation of this effect is immediately visible to the naked eye - smoke from fuel combustion does not come out as it should go into the chimney, but moves into the room, which creates a danger of human poisoning with combustion products and carbon monoxide. Why there is backdraft in the chimney and how to deal with this phenomenon, we will look at in this publication.
The reasons for this phenomenon
Reverse thrust, as it became clear from the above, there is a consequence, A . And above all, the main reason for poor draft in the chimney, and accordingly the appearance of this effect, is incorrect design of the heating system and non-compliance with the rules of use building materials for arranging a smoke exhaust system. Among other reasons, the most common are:
- Trivial blockage of the chimney.
- Incorrect calculation cross section chimney.
- Failure to comply with the height of the smoke exhaust system.
- The presence of horizontal and narrow sections in smoke exhaust ducts.
- The location of the chimney in the “wind pressure” zone.
- Improperly organized and insufficient quantity supply air.
But it often happens that the reverse thrust phenomenon occurs suddenly, on previously normally operating equipment. This may occur due to adverse weather conditions such as strong wind, fog or heat outdoor air in the summer. Each of these reasons can reverse the direction of movement of combustion products, thereby stopping the normal process of smoke removal from heating devices.
Oddly enough, the appearance of this effect is directly related to ventilation, or rather, the lack thereof. Warm air has more low density and therefore tends upward. Heated in the heating device, the air masses rise up the chimney, and colder air rushes into its place. But during work, it may happen that in a sealed room an area will gradually appear low pressure and the vacuum will become so strong that it will begin to draw fresh air from the chimney, “overturning the draft” and turning the movement of smoke into reverse side. The better the draft in the chimney, the longer there will be no effect of reverse movement of combustion products, but without a sufficient amount of supply air this process is inevitable.
In order to solve this problem, an influx of air masses from the street should be organized. This can be solved in several ways:
- By creating an influx of air masses through a loose closed windows, doors or windows.
- Installing supply wall valves.
- Mounting supply valves on PVC windows.
Each of these measures will facilitate the penetration of street air masses into the house, preventing a decrease in pressure in the room and the formation of a reverse draft effect. Which method to choose is best to consult with a specialist.
Ways to improve the removal of combustion products
Do not forget that even with the best ventilation system, smoke removal will be ineffective if the smoke ducts are clogged or improperly designed. There is only one way to deal with an incorrect project, dismantling the chimney and completely redoing it.
If there is a defect in the smoke exhaust ducts that reduces the removal of combustion products, you can use several devices that will improve this process.
Backdraft is a very dangerous phenomenon, not only due to the appearance of carbon monoxide in the living room, but also due to the generation of sparks directed into the room. At the first manifestations of this effect, you should stop using the stove or fireplace, try to independently determine and eliminate the cause, and if this does not give a positive result, immediately contact a specialist.
An unpleasant burning smell, smoke in the room, poor combustion of wood - all these are consequences of reverse draft in the chimney. This is a problem faced by many owners of fireplaces, stoves, solid fuel boilers and other wood-burning heating devices.
1. The chimney is clogged with soot
This is perhaps the most common and main reason worsening traction.
During the burning of wood, soot is formed. It consists of particles of combustion products that stick together and settle on the inner walls of the chimney, which leads to a narrowing of its diameter. As a result, air movement becomes difficult.
Therefore, soot must be removed regularly. This way you will not only improve traction, but also increase the operating efficiency and fire safety of the heating device. To make the chimney walls less contaminated with soot, you can use fuel wood briquettes, which contain less moisture and other harmful impurities.
2. Insufficient air flow
When burning wood, the air needs to move from bottom to top. That is, from the room into the chimney and out into the street. To do this, in the room where the heating device is installed, there must be an air flow - draft.
If all the windows are closed, if the ventilation is not working properly, then the smoke begins to move in the opposite direction - from the chimney into the room. That is, reverse thrust occurs.
The easiest way to solve this problem is to create proper air movement in the room. For example, open a window before lighting a fire and close it 10-15 minutes after the flame has flared up.
3. Cold outside air pressure
The draft in the chimney may deteriorate due to a decrease in outside temperature. Since cold air is heavier than warm air, it sinks down and “presses” inside the pipe. This problem especially often manifests itself in the presence of the previous two - lack of air flow and a clogged chimney. It strengthens their influence.
Therefore, the solution is: insulating the chimney, removing soot and creating an air flow.
Often a canopy is installed on chimneys, which can prevent smoke from escaping from the chimney. As a result, an air “plug” of smoke is formed and draft deteriorates.
In such cases, the visor should be replaced with a higher one or removed.
5. Incorrect chimney design
Backdraft can occur as a result of improper chimney design: narrow diameter, too high a height, or the presence of a large number of bends or narrowings.
To eliminate problems of this kind, you will have to rebuild the chimney, which will entail a significant investment of time, effort and money.
6. Brick collapse
Due to the constant heating-cooling process brick chimney, it may collapse. Bricks will fall off, fall down and clog the chimney.
To avoid such a situation, the chimney must be insulated. This will also solve the problem with cold air pressure.
CONCLUSIONS
So, how to increase draft in a chimney? Here are a few simple steps, not requiring special costs time and money:
- Clean the chimney of soot. This is the first thing to do. You can do this yourself with minimum costs time, effort and money.
- Provide air flow. Open the window for 5-10 minutes before lighting the fire. This will create the correct movement of air in the room from bottom to top. The window can be closed after the fire has burned out.
- Insulate the chimney if it is not insulated. This will reduce the influence of cold air and also extend the life of the chimney.
Having a heating boiler without automatic ignition, a fireplace or a stove, you will have to learn the profession of a stoker. You will need to know how best to place fuel, how best to light it, and much more. One of the necessary knowledge is what chimney draft is, what it depends on and how to make sure there are no problems with it. It's not as simple as it seems. There are many nuances.
What is chimney draft?
To understand what traction is stove chimney How it is formed and what it depends on, we must remember the laws of physics:
- More warm air has less weight and rises, the colder one is heavier, which is why it sinks down.
- Gaseous substances move from an area with more high pressure to an area of lower pressure.
- At the surface of the earth the pressure is higher, the higher we rise, the lower the pressure.
Based on the operation of these laws, smoke removal is arranged in heating boilers and furnaces: due to the difference in pressure/temperature, smoke and combustion products are discharged outside the room through the chimney. During normal operation, smoke moves from bottom to top, leaving the room through the chimney.
So, what is chimney draft: this is the movement of air along the chimney - from a lower point (indoors) to a higher one (outside above the roof). Essentially, air is “pulled” from the furnace/boiler into a zone of lower pressure (at a height of 5 meters above the “boiler level” the pressure is noticeably lower). Hence the common name for this phenomenon is “traction”.
During normal operation of the boiler or furnace, the smoke “disappears” into chimney. On initial stage, while the stove is not yet heated up and the fuel is not burning, air flows into the chimney due to the pressure difference that is formed due to the height of the pipe. Later, when the temperature in the furnace rises, the air warms up and becomes lighter, and the speed of gas movement through the pipe increases. The traction “works” normally.
But there is draft in the chimney if there is an influx of fresh air in the room - due to ventilation holes or cracks in the windows - depending on who you are. If sealed double-glazed windows are installed and there are no supply openings/ventilators leading to the street (or at least to a room with air flow), then there will be no draft. There is no air movement and everything does not work. The smoke escapes weakly/poorly or generally into the furnace room. There is simply no draft in the chimney - no air movement from bottom to top. The solution to the problem is to make inlet holes and everything should work. In general, there are quite a few reasons why there is no traction, but this is one of the main ones.
How to check
You can check the presence and “quality” of draft in the chimney very simply: using a lit candle or match or a sheet/strip of paper. It is easier to determine with a sheet if the draft in the ventilation duct is checked, with a flame - when checking the operability of the chimney.
The easiest way to check for draft in a chimney is to hold a burning match or candle
First, let's figure out how to check the draft in the ventilation duct. Take a piece of paper and bring it to the opening of the exhaust ventilation duct. If there is a grate, the sheet is attracted to it and “sticks” and is not easy to tear off. In this case, the draft in the ventilation duct is considered normal. If it is easily removed, the traction is insufficient; if it does not stick at all (falls), there is practically no air movement.
You can also check the traction using a strip of paper - if there is traction, the strip should be pulled inward
When checking the chimney draft, the situation is similar, only we use the flame of a candle or match (not as convenient as with a candle). We bring a lit candle or match to the open door of the boiler (solid fuel, liquid fuel) or to the slot for igniting a gas one. Observe the behavior of the flame:
In case of insufficient draft or its complete absence, it is necessary to take urgent measures to normalize smoke removal. Otherwise, you can get burned - smoke and carbon monoxide (CO) will go into the room, which will lead to poisoning. Automated gas boilers, with insufficient traction or its complete absence, they will not work at all. They have built-in sensors and if the air movement through the chimney is insufficient, the gas is shut off. Disabling the sensor is very dangerous. It’s better to figure it out and improve the draft in the chimney.
What to do if there is reverse draft in the chimney
Sometimes while the stove/boiler is operating, smoke begins to enter the room. In this case, they talk about the occurrence of “reverse thrust” or its “overturning”. A very unpleasant and, in some cases, dangerous phenomenon. There are several reasons, as well as solutions.
Draft overturning (reverse draft) usually occurs when the chimney height is insufficient
No air flow
In the struggle to reduce heating costs, home and apartment owners often make the mistake of sealing the room. Plastic or metal-plastic windows with double-glazed windows, all cracks and crevices are carefully sealed. There are no supply ventilation holes at all. In this case heating boilers will practically not work. While the pressure in the room is higher, air/combustion products are still removed from the room. This happens through the chimney, the hood above kitchen stove. There is no inflow, the pressure in the room decreases. When the pressure outside becomes higher than inside, smoke enters the room. They say that “the draft has capsized.”
A prerequisite for the presence of traction is the presence of air flow
In this case, getting rid of reverse draft is simple - providing air flow. The easiest way is to open a window or window. The smoke should go up the chimney, the situation will return to normal. But of course, this is not a solution to the problem. To get rid of draft overturning completely, it is necessary to make fresh ventilation.
Low pipe
When installing a chimney, it is necessary to follow the recommendations of the boiler equipment manufacturer. They are prescribed in the operating instructions. There is such a point as the minimum chimney height. Under any conditions, your chimney cannot be lower than the value specified in this paragraph.
But there is one more “general” rule: the pipe above the roof ridge must rise at least 50 centimeters. In most cases, this pipe height is sufficient for good traction. If the pipe is not high enough, when there is a gust of wind, the air flow swirls and enters the pipe. Since it is much colder than the air in the chimney, it rushes down, carrying smoke into the room with it. The solution to the problem in this case is to extend the pipe to the required height.
Insufficient insulation
(metal single-walled or asbestos too) can cause the draft in the chimney to tip over in winter during frosts. Even if your pipe is insulated (sandwich type), with strong gusts of wind there is a sharp removal of heat, which is why the smoke cools sharply and rushes down.
Solid fuel boilers usually cope with short-term gusts - the temperature of their gases is higher and it is not so easy to cool them down. But gas ones (especially low-temperature condensing ones) often turn off - the reverse draft sensor is triggered, and the gas supply stops.
The solution to the problem in this case is additional insulation(“Isover”, in colder regions with additional brick lining).
Large room with drafts
This problem often occurs in cottages with a fireplace. A fireplace is usually made in the living room - a large and spacious room with high ceilings. If there are drafts in the room, it is quite possible that the draft will overturn.
The second case is a house under construction. Having placed the box and installed the stove, the owners continue to lead Finishing work. Doors are often only entrance doors. If in such a situation the draft in the chimney overturns, install doors to the furnace room (or to the room where the stove is located). At the same time, do not forget that there must be an air flow (supply ventilation ducts). This should solve the problem.
Incorrect chimney arrangement
Often the cause of unstable draft is improper chimney design. For normal operation boiler/sauna or heating stove/stove, it is necessary to raise the chimney from the roof by at least 50 cm. Then it can be turned in the desired direction, making a horizontal section (but not with a reverse slope). This vertical section is necessary for “overclocking” flue gases. In it, they pick up speed and then overcome horizontal sections without problems (their total length is no more than 3 meters).
An important point: the accelerating vertical section of the chimney is best made from a pipe with smooth walls. Even if you have a boiler with low temperature exhaust, do not use corrugated pipe. Due to the unevenness of the walls, “acceleration” is slowed down, and periodic overturning of the thrust is possible.
Another reason for poor draft in the chimney is its small cross-section. Sometimes, to save money, they install a chimney with a diameter less than the nominal one. The solution is obvious - increasing the cross-section of the chimney. If the fuel burns quickly and there is little heat, dampers are installed on the pipe to regulate (reduce) the draft. But installing a pipe of a smaller diameter is not something you should do for sure.
Blockages and soot
Sometimes the draft in the chimney “disappears”. Most often the cause is a clogged smoke duct. It could be soot, some foreign object, a bird caught in it, etc. It can be treated simply by cleaning the chimney.
First you need to inspect the pipe, checking if there are any foreign objects in it, and then start cleaning the pipe from soot. There are many ways - from traditional mechanical cleaning using special brushes, to chemical ones - special logs or liquids that are used to heat the stove/boiler. There is also traditional methods- heating with aspen wood (can be dangerous if there is a large amount of soot), burning potato peelings(more long way cleaning the chimney from soot, but also safer).
Ways to improve chimney draft
In some cases, everything has been checked, all defects have been eliminated, but the draft in the chimney is insufficient, or periodically overturns. Most often this is observed in areas with complex terrain, with unstable winds, if there are trees growing nearby. big trees or close to each other high buildings. Air flows are reflected from a nearby obstacle and enter the chimney. For such cases, there are devices to increase chimney draft, you can:
