As an amplifier chimney do-it-yourselfers - photo and

The design of the chimney is complex and responsible, on the correct implementation of which depends on the efficiency and safety of using the heater. No heat generator is able to function normally without a pipe, which removes smoke from the room. Smoke is a mixture of gases containing residual products of combustion of fuel. The appearance of smoke inside the heated premises is a sure sign of an incorrect calculation of the chimney system, which entails the risk of fire and carbon monoxide poisoning. This article will tell you what reverse thrust in a chimney is, how to prevent it from occurring.

Measurement Methods

If you doubt that the chimney duct of the furnace, fireplace or heating boiler is sufficient, you need to check. The easiest way to dispel doubts is to check it with an anemometer. If the device shows a thrust of 10-20 Pa, then it is considered normal.. The problem with this method is the low accuracy of measuring inexpensive anemometers; if the thrust is less than 1 Pa, then they will show that it is not there. More accurate professional devices are expensive, they are used by stove-makers.

If you do not have an anemometer, use one of the popular methods for determining the chimney thrust force:

1. In the smoke. The most obvious sign that there is no traction - the presence of even a small smoke inside the room, a large amount of smoke indicates a high risk of fire and carbon monoxide poisoning.
2. According to the color of the flame. Looking at the color of the flame, you can check the level of thrust. If the flame inside the furnace has a white tint and crackles during burning, the thrust is excessively strong. Orange-red color says about the lack of bollard. If the chimney is designed correctly, the flame has an even golden yellow shade.
3. With the help of a match. If you light a match, a candle or other source of fire and bring it to the heating device, the flame should deflect to the firebox. If it remains smooth, you can be sure that there is no traction. When the flame is deflected to the side opposite to the firebox, there is a reverse thrust in the chimney.
4. With the help of a mirror. Another method to test the thrust inside the chimney is to bring a pocket mirror to the firebox. The appearance of condensate on its mirror surface means that the removal of smoke is difficult.

Note! Traction inside the chimney channel is created due to the difference in pressure on the street and inside the room. In a heated room, the temperature is higher than outside, so there is more pressure. The heated air, supported from below by cooler air, is squeezed out into a zone with a lower pressure, that is, into the atmosphere. If you take measurements in summer, when the temperature difference inside and outside is minimal, you will get less result than in winter.

Causes of faults

Making sure that there is not enough traction inside the chimney system, it is necessary to determine and eliminate the possible cause of this defect. Experienced craftsmen claim that the most common causes of failure of the smoke exhaust channels are:

• Design error. Make the choice of chimney should be, focusing on the volume of the furnace. If the diameter is less than the calculated parameter, weak will not allow the smoke to leave their premises.
• Insufficient pipe length. A pipe length of less than 5 m does not provide a significant difference between the pressure inside and outside, which creates weak traction.
• Incorrect chimney tube placement. Oven masters I advise you to lay the chimney vertically, as narrow turns detain the smoke inside the pipe, reducing cravings.
• Large horizontal stretches. If, laying the chimney, you cannot avoid horizontal sections, then make sure that their length is not more than 100 cm. Otherwise, it will need an amplifier.
• Wrong position relative to the ridge. Chimney located on the same level or above the ridge of the roof. The ridge in the windward position dramatically reduces the force of thrust in the chimney.
• Hit in the area of ​​the wind backwater. If there is a high structure in the neighborhood of the house, it blocks the chimney from the wind, preventing the chimney system from functioning properly.
• Weather. Sometimes the draft is reduced due to a decrease in atmospheric pressure, moisture entering the chimney due to rain, fog or snow. However, these changes are not terrible, as they are temporary.

The first step in detecting problems in the chimney system is to remove the most obvious causes of insufficient thrust. During the inspection, make sure that all the segments of the pipe are tight, and that there are no particulate congestion. Check that no moisture has entered the flue ducts and that the atmospheric pressure is normal.

Ways to enhance traction

If the thrust force in the flue duct of the heater is not always easy to eliminate this defect. Experienced stoves use the following methods, ways to increase it:

1. The first thing to do if you suspect insufficient chimney draft is to clean the chimney. To do this, they call the chimney sweep or remove the soot deposits from the inside of the chimney with their own hands using a metal oven ruff.
2. A significant increase in the power of the chimney can be achieved by increasing the height of the chimney above the surface of the roof, putting it in a few additional segments. The same method removes the chimney from the area of ​​the wind backwater from the ridge or a higher building.
3. Installation of rotary turbines. This device, which is installed on the top of the chimney, consists of one or more screws. Under the influence of the wind, the turbines rotate and create a vacuum in the air to achieve a greater difference between the internal and external pressure. The use of turbines is effective only in windy weather, they are recommended to be used if the smoke temperature at the exit of the chimney is not more than 200 degrees.
4. Using a special deflector. Special models of deflectors have a special aerodynamic shape. Due to the property of air to lower the pressure during the fall effect during the passage of an obstacle, a rarefaction zone is created in the deflector, which stimulates the smoke to leave the pipe. The effectiveness of aerodynamic deflectors is noticeable only in windy weather.
5. Amplifier thrust. A device for automatic thrust control is an umbrella-shaped cap with a thermal sensor mounted on a chimney pipe. Thermal sensor analyzes the temperature of the exhaust gases and works independently. The traction booster keeps the pressure in the chimney in the range of 10-35 Pa, optimizing the operation of the heater and fuel consumption.
6. Smoke exhauster If there is no effect from the previous methods, a smoke exhauster fitted with a screw and an electric motor is installed on the pipes. In windy weather, the screw rotates independently, if there is no air movement, the electric motor is activated and sets it in motion.

If you did not manage to find a solution to the problem of lack of traction inside the exhaust duct, consult an experienced stove, who will tell you what to do, fix the defect in the most rational way.

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