Stoves and fireplaces give any home a unique coziness, but, like any heating systems, they require regular maintenance. Over time, condensation forms on the chimney pipe, which flows down and has a destructive effect on it. In common parlance, this phenomenon is called “the oven is crying.” To avoid unpleasant consequences It is possible if a high-quality condensate collector is installed at the construction stage of the house. In case of its absence there are several effective ways minimizing the formation of condensation.
Condensate is a tarry liquid mass that settles on the inner walls of the chimney as a result of contact of air flows of different temperatures. Hot smoke, rising through the pipe, gradually loses temperature and, having cooled, releases water vapor, which condenses, turning into liquid. In this case, it mixes with combustion products, resulting in the formation of acid.
Almost all modern gas installations have a fairly low temperature of combustion products at the outlet, which is the reason for the cold walls of the chimney. The formation of condensate begins already at a temperature of exhaust gases of 45-60°C. And if in a steel pipe with a smooth surface the liquid flows down without stopping, then on the brickwork it gradually accumulates, leading to the destruction of the pipe.
The amount of condensate may vary for a number of reasons, knowing them you can minimize the formation of liquid on the walls of the chimney:
In addition to the reasons listed, the appearance of liquid in the pipe can be caused by a violation of its tightness. Cold air entering from outside through the cracks will cool the flow of gases and promote condensation of water vapor.
To ensure normal traction, it is necessary to use exclusively dry fuel, which will quickly warm up the device and after its combustion there will be no deposits left inside the pipe. Damp firewood does not provide the required amount of heat and, when burned, releases a lot of wet vapor, which settles in the form of condensate. Using high-quality fuel will extend the life of the chimney and the stove itself. For normal drying, the firewood must lie in a dry place for at least one and a half years.
Equipment operating on natural gas, more susceptible harmful effects condensation and therefore more often fails. When installing gas equipment, it is advisable to take care of the condensate collector in advance, otherwise you will have to constantly clean the chimney. Often in the operating instructions, the manufacturer indicates how best to protect the system from condensation.
Water vapor from the exhaust gases, turning into water, settles on the cooled inner surface of the chimney. Drops of liquid, mixing with other combustion products, flow down the pipe, gradually rendering it unusable.
This destructive effect is due to the aggressiveness of the mixture of condensate and soot deposits. The acid formed on the inner walls over time corrodes the metal and other materials from which the pipe is made. It is worth noting that the problem of the appearance of acid condensate is inherent only stove heating. In case of use gas equipment Liquid is formed only from water vapor.
Especially fast acid solution destroys the brickwork of the upper section of the pipe, which in the cold season is often subject to freezing and thawing. Falling bricks and dark streaks of unpleasant odor are the consequences of irresponsible installation of a brick chimney in our climate.
Acidic condensate eats through chimneys made of ordinary steel. Moreover, attempts by some owners to protect them from the outside with anti-corrosion agents do not bring results, since destruction occurs from the inside. Pipes from of stainless steel will last much longer.
The accumulation of liquid in the pipe also leads to deterioration in traction, which will result in bad smell in room.
The amount of condensate formed and the normal functioning of the heating system for a long time depend to a large extent on the material of the chimney pipe. Pick up best option It’s better at the construction stage, otherwise a failed chimney will have to be completely replaced, which will be problematic to do later.
A pipe made of bricks has the property of accumulating heat and not cooling down for a long time, preventing cold air from falling down, which ensures normal draft in the chimney duct. But this advantage is also a disadvantage brickwork, since it takes quite a long time to heat up the pipe and condensation forms intensively at a low channel temperature. Brick pipes are most susceptible to destruction due to sudden temperature changes in winter and exposure to acidic mixtures. To extend the life of the chimney duct, the internal cavity is lined with stainless steel pipes.
There are two types of such chimneys:
Double-walled pipes have additional insulation made of basalt fiber, which is laid between the inner and outer walls. The steel quickly warms up, providing normal traction and, thanks to the insulating layer, cools down for a long time, which reduces the possibility of condensation formation to a minimum. Smooth inner surface prevents the accumulation of water and soot deposits. The only drawback of stainless steel chimneys is the possibility of icing outer surface at low temperatures and the need for additional insulation of single-wall pipes.
Ceramics – durable material, resistant to the destructive effects of condensation. It warms up quickly, retains heat for a long time and is not afraid of soot fires. The cost of ceramic pipes is low, but due to their heavy weight, installation difficulties arise.
Furanflex is a modern composite material, consisting of a polymer resin, fiberglass reinforced. Furanflex pipes are resistant to corrosion and aggressive environments and are easy to clean mechanically. Available in diameters from 60 to 1000 mm. In this case, the length of the chimney duct does not matter - polymer hoses are available in any length. The finished furanflex channel will be absolutely sealed, ensuring normal traction and no leaks.
Installation of such a chimney does not require dismantling walls or structures. The installation process is clean and can be done when Finishing work finished. The material can withstand temperatures up to 250°C for a long time. Manufacturers guarantee uninterrupted operation furanflex pipes for 30 years.
As noted above, it is not possible to completely eliminate the formation of condensation, but it is possible to reduce its amount to a minimum. There are several proven methods for this:
Not only the fuel used and suitable material pipes, but also a chimney system installed according to all the rules:
To prevent the accumulation of condensate in the chimney, it is necessary to install a condensate collector and drain. And do not forget about regular cleaning of the equipment and the internal cavity of the chimney.
Condensation also causes metal pipes to burn out. True, the pipes do not burn out, but are destroyed due to corrosion. The fact is that there is sulfur in the fuel. When it burns, sulfur dioxide is formed, which, when mixed with water, forms sulfuric acid. The destruction of pipes does not occur in the lower, hottest part, but at the very top, where the temperature is lower. Condensation almost always forms in metal pipes. Therefore, for their manufacture it is necessary to use special resistant varieties become. The most common grade of steel used to make stoves and fireplace pipes is 304 stainless. It is heat-resistant and resistant to weak acids. But it should not be used for boilers that use coal and gas as fuel. In this case, 316 stainless steel is used. This is an acid-resistant steel. And 321 stainless steel is the most resistant to both heat and corrosion.
What is the reason for the formation of condensation? Water evaporates and, accordingly, condenses at a temperature of 100 degrees Celsius. Therefore, the temperature at the outlet of the pipe must be at least 100 degrees. Better than 120. At the level of the upper gate, the temperature should not fall below 200 degrees Celsius.
To determine the temperature, a splinter is inserted into the neck of the upper gate. After 30-40 minutes, remove the splinter and clean off the soot. If the color of the splinter has not changed, then the temperature of the gases is less than 150 degrees Celsius. At temperatures up to 200 degrees, the splinter turns yellow. If the splinter is brown, then the temperature is up to 250 degrees. With more high temperature the splinter is charred.
A decrease in the temperature of gases in chimneys occurs for the following reasons:
The presence of gaps and cracks in the masonry;
Air intake through cleaning doors;
Too much or too little air is supplied through the furnace vent. With a properly adjusted air supply, the flame is straw-yellow in color;
The length of the smoke circuits is too long or the volume of the bell part is too high. In this case, partial or complete refurbishment of the furnace is necessary;
During the cold season, condensation can form when a pipe passes through an unheated second floor. Or when the pipe rises very high above the roof. In this case, it is necessary to insulate the pipe by plastering it or other finishing methods. The wall thickness of the pipe passing through the room must be at least 12 cm (half a brick). Pipes standing behind the walls of buildings are laid with a wall thickness of at least 1.5 bricks.
To avoid cooling of the pipe wall, the pipe cross-section should not be increased beyond what is necessary. For furnaces with power up to 3000 kcal. h a pipe with internal size 13x13 cm (brick floor). For more powerful stoves, the chimney size is 13x27 cm (brick).
Condensation can form when water enters the pipe. To protect against precipitation, it is necessary to protect the pipe with a cap.
In conclusion, I want to say that it is always easier to avoid such unpleasant things as the formation of condensation than to deal with it later. And for this you need to place the stove correctly. And it’s better to invite experienced craftsman, than to do the laying of the stove yourself.
Along with gas stoves and fireplaces, many summer residents are increasingly paying tribute to various types of stoves- heating and cooking options of the traditional “Russian” one.
Especially in buildings for year-round use. This is understandable: it’s nice to warm up in the winter cold on a warm, breathing bed.
Where heating is carried out primarily with wood, stoves often suffer from one very serious drawback: they condense, that is, a black liquid with a specific odor accumulates in their chimneys, resulting from the deposition of water vapor and vapors of resinous substances on the walls of the chimney.
IN subsequently, condensation saturates the stove masonry, it becomes damp and black, and begins to collapse, and thrust flue gases decline. In addition, the odors can be so strong that in some cases living in the house becomes unbearable.
On external sides spots and stripes of black color appear in the oven, and it happens that most of the oven turns black. If the brick is not deeply saturated, then it is better to cut it down and plaster such places cement mortar. But more often the masonry is replaced: after all, at the beginning, condensation appears at the top of the stove and the bottom of the pipe, that is, near the attic or interfloor covering- where the furnace itself ends.
Even the driest fuel contains a small amount of moisture. In addition, the hydrogen contained in the fuel, two parts by weight of which combines with one part by weight of oxygen, also forms water vapor.
Flue gases with a low temperature and a certain amount of water in the form of steam, passing through the channels of the furnace and pipe, are cooled in contact with the cold walls of the pipe, and settle on them in drops that flow down. The amount of drainage depends on the amount of condensate.
In order for the existing water in the hot (flue) gases to evaporate better, the temperature of the latter must be increased.
On well-heated pipe walls, settled drops of moisture quickly evaporate.
It has been established by practice that normal temperature gases leaving the furnace, before entering the pipe, have about 123 ... 140 degrees, and when leaving the pipe into the atmosphere - not lower than 100 ° C. If the flue gases at the upper damper (see Fig. 1) reach a temperature of about 250 ° C , then condensation never occurs, draft becomes better, stoves heat up faster, while consuming less fuel.
Rice. 1. Oven (front view and section). on the right is a section: 1 - firebox, 2 - smoke channels and chambers, 3 - upper and lower dampers.
You can determine the temperature of the exhaust gases in a simple way, using dry wood chips, which are placed across the opening of the upper damper during combustion. If after 30-40 minutes you take out a chip and scrape off the sooty surface with a knife, then the temperature of the gases can be determined by the color of the cod: the color of the cod does not change at a temperature of about 150 ° C. If the wood turns yellow (to the color of the crust of white bread), this means the temperature reached 200 ° C, and if it turned brown (the color of the crust of rye bread), then the temperature rose to 250 ° C. Cod turns into coal when the temperature reaches 400 ° C. Thus, when firing the oven, the temperature of the gases can be adjusted, trying to at the top damper it was about 250 ° C.
Spotted, what in warm time years, condensate either does not form at all or forms in small quantities. In the appearance of condensation, many features of the structure of the stove itself play a large role: the dimensions of the grate, the level of the hearth, the structure of the furnace of a Russian stove, the dimensions of the channel, the thickness of the walls, the length and height of the chimney, the temperature of its heating, the humidity of the fuel used, the temperature of the exhaust gases and even number of chimneys in the stove.
Various cracks in the pipe and furnace, through which it penetrates cold air, also contribute to the cooling of hot gases, cooling the pipe and the formation of condensation.
TO when the cross-section of the pipe channel is higher than required for a given furnace, then the flue gases rise slowly through it, and the cold outside air cools them in the pipe.
Great influence on traction force, i.e. to the exit of flue gases, has the smoothness of the walls of the chimneys. The smoother they are, the stronger the pull. All roughness in the pipe helps reduce draft and retain soot.
The height of the chimney must be at least 5-6 m, counting from the level of the ash chamber or the hearth of a Russian stove.
The thickness of the pipe walls should be half a brick (12 cm): thinner walls heat up quickly and cool quickly, which leads to the formation of condensation. Such pipes must be insulated (Fig. 5 and 6) with non-flammable thermal insulation materials(slag wool, glass wool, thermal concrete slabs, etc.).
Rice. 5. Heat-insulating thickening in the chimney wall.
Rice. 6. The structure of the otter (the junction of the stove and pipe).
Sometimes, to improve draft in furnaces, it is necessary to re-arrange the pipes, reducing the size of the chimneys (see Fig. 4).
Fig.4. Chimney cross-section: a - normal, b - narrowed.
For the same purpose, the height of the pipe on the roof is reduced or increased (see Fig. 3).
Fig.Z. Chimney size: above gable roof(A), gable (B) and on a roof with a ledge (C).
They do this until they get a satisfactory result. Moreover, during the inspection, the pipe above the roof can not be laid from brick, but can be made according to the size of the channel from roofing steel, square, which will fit into the brick one, laid out within the attic. This pipe is raised or lowered during inspection, achieving best results and determining its height above the roof level, after which the brick pipe is finally laid out.
In places where chimneys narrow, corners should be cut off or filled in (see Fig. 4) to ensure a smoother transition of gases; they should be well rounded and better leveled so that they are smooth and less susceptible to damage from heating.
Fig.4. Options for anti-condensation devices in heaters (shaded).
Rice. 5. Options for concrete pipe design: A - otter, B - head.
The wind also affects the draft in the pipe. It is better when it blows horizontally: having met the pipe, the flow deviates upward, towards the outlet of the pipe, where the air is discharged, and the gases better come out of the chimney, as if sucked out of it. If the wind blows at an angle downward, it blows (overturns) gases into the pipe, and the thrust is reduced to a minimum.
To reduce the impact of wind on the gases coming out of the pipe, it is better to cover it on top with metal parasol caps with beveled planes. Hitting them, the wind deviates from its original direction and does not enter the pipe. In addition, the cap protects the top of the pipe from bad weather, and its walls from getting wet and washed away by rain jets. In damp pipes, draft is greatly reduced.
The process of fuel combustion itself also plays an important role. Wood ignites at a temperature not lower than 300 ° C, coal - at 600 ° C. The normal combustion process occurs at a higher temperature: wood - at 800 ... 900 ° C, coal - at 900 ... 1200 ° C. Such temperatures ensure continuous combustion provided that air (oxygen) is supplied without interruption in the quantity necessary for combustion. When too much of it is supplied, the firebox will cool and combustion will worsen, because for good burning high temperature is needed. Do not light the stove with the firebox open.
When fuel is completely burned, the color of the flame is straw-yellow., and the smoke is white or almost transparent. In this case, almost no soot is deposited on the walls of the furnace channels and pipes. If there is insufficient oxygen supply to the furnace, the fuel does not burn completely, the wood smolders or burns with a dark red flame, and black smoke comes out of the chimney, which carries with it unburned tiny particles fuel. In this case, these soot particles settle on the walls of the furnace channels and in the pipe and quickly clog them.
Soot is formed from various fuels, but more often - from one that contains resinous substances (wood coniferous species, birch, especially its bark; coal and especially liquid fuel). In addition, it clogs the channels, the soot can catch fire, and this is dangerous. When dry aspen firewood is used for fuel, almost no soot is deposited.
Therefore, when heating, it is recommended to systematically use aspen firewood - at least once a week, even better - two, and if three, excellent. The soot from such fuel gradually burns out and the chimneys are cleaned. The only drawback of such firewood is that they “shoot” (pop and sparks fly).
It is worth paying attention to insulation attic space and the pipes located there. The attic should be relatively warm, then the pipe does not cool so quickly. This mandatory requirement to combat condensation.
The formation of condensation is facilitated by the so-called hogs ( reversible sleeves) in the attic. In addition, they are dangerous in terms of fire. Therefore, it is recommended to keep hogs only indoors.
Insulation of pipes in the attic is done with slag wool or glass wool, from which thick (2-4 cm) “blankets” are sewn, using the same threads. The pipe is tightly wrapped with these blankets. You can make slabs based on slag (1 part cement and 3-4 parts slag sand). This and slabs the right size 3-4 cm thick, mounted on clay solution to the pipes, coating the seams well.
A few words about the stoves themselves.
Are there multi-channel or ductless stoves?, with large internal heat-receiving surfaces. Hot gases give off a lot of heat to such furnaces, and they themselves exit into the chimney very cooled, forming large condensation. It is not so much the stove makers who are to blame for this, but rather the residents themselves, who demand a stove with a large number of channels “for heat.”
Furnaces have to be remodeled or rebuilt in order to increase the temperature of the flue gases. This is achieved by the following measures: reducing the internal heat-receiving surfaces of the stove or installing small window openings from the firebox into the last and penultimate chimneys.
To rebuild such furnaces it is necessary to dismantle part of the stove masonry from one side, often from both sides, and after correction, lay it in such a way that the place being repaired is no different from the previously completed masonry.
For example, when a stove has seven chimneys, then in order to eliminate condensate, one or two channels (the last and penultimate) or only one of them is turned off, blocking at the top and bottom, due to which the temperature of the exhaust gases increases.
These channels can be left on, and make small channels for them from the firebox of the stove with a cross section of approximately 5x5 cm. They are laid out square in brick so that their area is at least 25 sq.cm. This method is also reliable, as it increases the temperature of the exhaust gases to normal: streams of hot air from the firebox enter the channels, raising the temperature in them. Practice has shown that the greatest effect is achieved by slightly reducing the channels, and in the remaining two (the last and penultimate) windows from the firebox are installed.
Modern man is very thermophilic. If you, our dear reader, have your own home, then you have to solve the problem of heating it yourself. But modern heating equipment different from the fireplaces of the past; together with increased efficiency the complexity of the design increases and the maintenance of units becomes more complicated.
When modern boilers, stoves and fireplaces operate, condensation inevitably forms in the chimney.
Whatever type of fuel you use, you burn hydrocarbons. Coal, coke, firewood, fuel oil, gas, pellets - everything consists of hydrogen and carbon with small admixtures of sulfur and some others chemical elements. Any fuel also contains a small amount of water - it is impossible to completely remove it. During combustion, they are oxidized by atmospheric oxygen and the output is water, carbon dioxide, other oxides.
Sulfur oxides at high temperatures react with water and form very aggressive acids (sulfuric acid, sulfurous acid, etc.), which also enter the condensate. A few other acids are also formed: hydrochloric, nitric.
There are two immediate dangers when condensation forms:
An aggressive acidic environment, collecting on the walls of a chimney, leads to its rapid destruction - acids corrode the steel, corrosion occurs - the metal quickly rusts and “burns out”. are also destroyed by acid condensate.
In addition, condensate flowing into the boiler furnace also destroys the heating unit (and in very large quantities it can extinguish the fire in the furnace).
A large amount of moisture settling on the walls can also lead to unpleasant consequences:
The photo below shows the consequences of repeated freezing of a brick pipe.
The exhaust gases contain water and other liquids in the form of steam. When the gases are cooled, the steam becomes supersaturated, the water collects in droplets and tends downward - this is the most main reason the appearance of condensation. In a flow of hot gases, this process occurs near the colder walls of the chimney - and it is there that drops of liquid settle, forming condensation.
When considering the reasons for the appearance of condensation, it should be borne in mind that there is no smoke without water vapor; the presence of liquid collecting on the walls of the chimney cannot be avoided.
Reasons for the increase in the amount of condensing liquid in chimneys:
It is impossible to completely eliminate condensation. If you think that " before the oven been heated for centuries and there was no condensation,” then it should be borne in mind that now the fuel is burned almost completely, the efficiency of heating units is greater than that of more primitive models wood stoves and fireplaces of past centuries, the temperature of the flue gases is lower - hence large quantity aggressive liquid in chimneys.
It is possible to achieve such operation of the equipment and pipe design that almost all the condensate will be carried away into the atmosphere by very hot smoke - but it will also carry away a considerable share of heat and your money.
But all is not lost - measures can be taken to reduce the amount of condensed liquid
Alpha and omega chimney devices. Any chimney must be insulated all the way to the top. Old brick pipes It is also recommended to additionally insulate above the roof and in the attic.
An uninsulated chimney has no right to exist at all.
Firewood needs to be dried! First - under a canopy or in a spacious, ventilated barn, optimal time drying - one and a half to two years. Finely chopped firewood dries faster. Before use, let them sit for a week or more in a warm, dry room. Constantly burning wet wood will result in smoke. large quantity moisture, wasteful consumption of firewood, incomplete combustion and the emission of large amounts of soot (and the need for more frequent cleaning smoke channel).
Coal, peat - do not wet. Bring it into the room in advance, let it warm up and dry out the moisture that has settled on it. Pellets, briquettes - protect from getting wet, store in a dry, warm room.
Firewood, pellets, briquettes (especially firewood) initially have higher moisture content than firewood or fuel oil. But it is more reasonable to choose the type of fuel for a heating unit, based on the parameters of fuel cost, availability in your area, and the need to automate the heating system.
The smoother the internal surface of the smoke channel, the better the draft and the more moisture"will fly down the drain." Therefore, the chimney should be cleaned of soot regularly, without waiting for the draft to deteriorate - at least twice a year. Cleaning methods - mechanical or chemical - are not of fundamental importance.
At different types fuel is formed different quantities soot For example, for gas boiler the amount of soot formed is minimal, for a coal furnace it is maximum.
- a completely affordable activity to do yourself. In our video you will see all the intricacies of chimney cleaning.
What to do if condensation flows along the walls of the chimney? Install a container to collect condensate. This is an absolutely necessary event in modern heating systems. Condensate drain - a stainless steel container for collecting condensate, mounted in the lower part of the vertical channel, below the outlet channel or pipe of the heating unit, with access for emptying it. Sometimes a permanent drainage of condensate from the tank into the sewer is arranged. In modern metal “sandwich systems” and ceramic pipes The range includes ready-made sections for mounting such containers.
Old chimneys It is also worth upgrading by integrating a condensate trap glass into the lower part.
Basic preventive measures to reduce the amount of condensate:
Requirements for the design of chimneys are determined by SNiP 41-01-2003.
Primary requirements:
We hope, our dear reader, that this article will help you understand the operating features of modern chimneys and choose one for your home. optimal design smoke removal systems, protect equipment from aggressive condensate. Subscribe to our newsletter - and you won't miss a new one useful information about construction and repairs and you can discuss it with friends on social networks.
The resulting condensation has a detrimental effect on the entire chimney structure. To eliminate this problem, you need to have information about the structure of the chimney. Having this information, it is much easier to understand the problem.
When fuel is burned, flue gases are formed. They are saturated with soot and water vapor. Moving up the pipe, these formations cool and condensation appears in the chimney. Soot and steam settle on the walls of the pipes.
When too much condensation accumulates, a black, tarry liquid begins to form. There is a pungent odor. This resin passes through the masonry, destroying and soaking the entire structure of the furnace.
The formation of condensation in a stove chimney is influenced by many factors. The main ones:
Every combustible fuel used by humans has an efficiency factor below one hundred percent. Those. The fuel does not burn completely, and during its combustion carbon dioxide and water vapor are formed. Due to the release of these carbon dioxide and water vapor, condensation is formed.
If the chimney has low draft, then the smoke, without having time to cool, turns into steam and settles on the walls.
This problem is especially relevant during winter. It is characterized by different temperatures inside the chimney and in the external environment.
From the reasons for the formation of condensation, it is not difficult to understand that it is impossible to get rid of it once and for all. You can only reduce the amount of condensate or improve the quality of the chimney pipes.
