Return chimney draft - what to do? Causes of formation and elimination of reverse thrust in the chimney
Our grandmothers and grandfathers knew about the concept of reverse thrust. In almost every private house with a stove in the winter it was possible to 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 has not disappeared. Very often there is a reverse thrust in the chimney of a gas boiler or column. In order for the heater to not deteriorate and function properly, it is necessary to become familiar with the nature of this phenomenon.
The occurrence of reverse thrust
Call the directional movement of air through the chimney or other channel. Even from the school bench, we know that such a movement is caused by temperature differences or atmospheric pressure drops, since the density of warm air is less than that of cold air, and there is such a thing as a thrust that causes air currents to move.If such a process is carried out without the aid of additional devices or devices, then it is called a natural burden. When air flows turn around and begin to move in the opposite direction, and there is a reverse thrust in the chimney. What to do in such situations depends on many conditions. First of all it should be understood that the vacuum occurs due to the presence of sources of natural ventilation in the room. In order to avoid the smoke in the room, it is useful to know what kind of air comes out of the room, as much should go into it. With proper operation, it can be easily controlled, reducing heating costs and improving the quality of heating.
Interestingly, even with the proper arrangement of the chimney in a private house, there may be a short-term appearance of reverse thrust, called tipping. The reasons are often adverse weather conditions, and the effect persists for a long time.
At the beginning of each heating season, before starting up the boiler or furnace, it should be checked whether there is a back draft in the chimney. What to do for this? Of course, there are special instruments for measuring traction, but they are very expensive and are available only from specialists.From the experience of generations it is known that it is necessary to check the draft in the furnace with the help of a flame. For this, a match is lit and brought to the firebox. If the flame draws into the furnace, it means that the traction is good, and you can begin to melt the room. When the fire does not move - there is no traction at all, and if the flame blows into the room, then in the chimney the thrust is reversed. What to do when starting gas boilers? Open fire cannot be used. You should check where the smoke draws in by tilting a thin strip of paper.
The color of the burning flame can tell about the magnitude of the traction in the furnace. Ideally, it should be golden. If the color is red, then the fire does not have enough oxygen for normal burning, and if a hum occurs during the firebox, excessive exhaust can be judged.
Why does reverse chimney form?
A large number of factors affect this process. The main is the wrong design of the chimney at the construction stage. In order not to face the problem of insufficient or improper traction in the future, it is necessary to correctly calculate in advance:
- chimney section size;
- its location;
- production material;
- pipe height;
- the presence of additional devices that increase traction.
The quality of air movement is also affected by the amount of people consuming oxygen in the room or appliances. The latter include heaters, irons, stoves, and so on. It is important for proper operation and regular airing of the room.A person can control all this independently, therefore only the presence of reverse thrust in the chimney depends on him. What to do when influenced by weather conditions? It is impossible to control them, but to resist is quite realistic.
The main reasons for the adjustment of air flow
From the foregoing, it is clear that the rarefaction of the air is only a consequence of weather phenomena or human actions, so the elimination of reverse thrust in the chimney begins with an exact determination of the cause of its occurrence. The main is the wrong design of the entire heating system and smoke removal. In this matter, it is important to pay attention not only to the calculations, but also to the selection of the material. It is better to use ceramics or bricks for the stove chimney, but metal pipes are ideal for boilers or gas columns.In addition, the reason for the return thrust in the stove chimney can be hidden:
- in the clogging of the chimney;
- in the presence of narrow sections in the channel of passage of smoke;
- the location of the chimney in the channel "wind backwater";
- in violation of natural ventilation;
- under adverse weather conditions.
By the way, the presence of the correct air flow depends on the weather, even if all the rules for arranging the chimney are observed. Overturning occurs especially in high winds, high humidity or high temperatures outside the window. This is true when using a gas column in the summer.
In any case, if such a phenomenon occurs, it will not be superfluous to inspect the smoke exhaust paths and verify that they are working.
The device of the chimney in a private house always assumes the presence of a direct chimney, located strictly vertically. Such a technique is considered to be the most effective, since if there are bends on the path of smoke, inclined sections or horizontal pipes, the thrust will proportionally deteriorate, and the slowly passing smoke will accumulate a large amount of soot on the inner surface of the ducts.
You should also pay attention to the location of the chimney against the outer wall. This is very rare, since it provides for a slow warming up of the smoke paths and a large accumulation of condensate during cooling, which freezes through in severe frost. In the complex, these phenomena have the frequent occurrence of reverse thrust.
The least resistance to moving smoke in the right direction occurs only when there is a round pipe in the structure. It is considered ideal for arranging the chimney of any heating device.
It is important to know that depending on the type of heater being installed, the installation rates and connection rules will also change. Only with the correct calculation can one obtain effective operation of the heating system without the occurrence of rarefaction of air.
Influences the temperature of burning fuel. The higher it is, the stronger the thrust will be, but at the same time the need to get enough air for burning will also increase in proportion. If the ventilation does not provide it, the furnace or boiler will begin to take it from the room, thereby provoking the occurrence of reverse thrust.
To avoid this phenomenon, during operation of the furnace, it is necessary to use a chimney tooth in its design. The device is a small ledge between the firebox and the smoke box. Reverse traction in the gas column chimney elimination involves installing an intake valve, but its operation does not always help to really solve the problem.
Materials for the arrangement of the chimney
In order to avoid further problems with the heating device, it is necessary to choose the right material in advance for arranging its chimney. Absolutely for all gas boilers, columns and other devices should be installed metal chimneys. This material contributes to the rapid heating, but also the same rapid cooling.
For sources of heating in the house that use solid fuel for their work, brick or ceramics will be the ideal covering for the chimney. Such materials contribute to greater heat, but at the same time retain heat better.
It is important to pay attention to the smoothness of the surface when arranging the smoke exhaust paths. The smoother it is, the less likely it is to quickly accumulate soot and to clean chimneys.
In order to prevent the occurrence of backdraft during the heating season, you should regularly check the cleanliness of the chimneys before the need to use heating appliances regularly. Birds flying into the chimney, large accumulations of soot or flaking of the plaster from the inside of the chimney paths can cause blockages. You can check the cleanliness by looking into the pipe from the roof or through the cleaning door, but using a mirror.
If there is dirt in the pipe, they can be cleaned using special brushes and even chemicals sold everywhere today. In order to delay the cleaning of the chimney as far as possible, it is recommended to use one of the preventive advice transmitted by generations.
The first one says that every 10-12 fireboxes aluminum cans should be burned in a furnace. It is important that the burning temperature at the same time be such that the banks are completely burned in 5 minutes. It is also advised that if there is a large amount of soot in the pipe, throw approximately half a bucket of polished and chopped potatoes into the furnace during burning. The starch released during the combustion of the product will be able to soften the plaque, and the soot itself will crumble from the surface of the chimney.You can periodically burn rock salt in the firebox, this will also delay cleaning.
From the height of the pipe that removes smoke from the heater, the presence of thrust in it also depends. The chimney should be about 5 meters high, but not below the ventilation duct. Its top point should be 0.5 meters above the level of the ridge of the roof and approximately 1.5 meters away from it. This should take into account the presence around the house of trees or other buildings that may impair traction.
In a private house, the presence of natural ventilation facilitates the flow of fresh air into the room. In apartments, especially after repairs and replacement of windows, the room often becomes hermetic, and in the absence of air intake, a vacuum is created. In order for the situation to remain normal, during repair it is necessary to think about installing additional ventilation valves. To help in solving such a problem can ordinary kitchen extractor or air conditioning.
Elimination of reverse thrust
So, how to get rid of reverse thrust in the chimney? In most cases, this problem can be solved independently.To eliminate the short-term lack of traction in the furnace, you should burn a couple of newspapers to warm the air in the pipe, but most often the chimneys just need to be cleaned. If the traction disappeared after repair or did not appear at all, then an error in the calculations was probably made, and additional devices would need to be installed in the room.As such, there may be smoke exhausters, chimney vane and fans or deflectors. It may be necessary to increase the length of the pipe. You can also briefly open the window for airing and entering the room with fresh air or insulate the chimney, if its parts are located on the outer wall.
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 forbidden to use heating devices until the troubleshooting is resolved.