Already make a ventilation duct in an apartment building. Redevelopment of the ventilation duct in the apartment
Air exchange is provided by draft in the exhaust duct system. They start in rooms (usually in the kitchen and in the bathroom, in the "dirtiest" rooms in the house). Further, the air ducts go up, to the attic and from there - to the roof.
Air draft is generated in these ventilation ducts. Due to it, the exhaust air from the house goes out into the street. And to replace it, fresh air enters the house - through windows, doors, leaks in the walls and double-glazed windows.
The air moves through the exhaust ducts due to two simple laws of physics:
- Warm air tends upward
- Air rushes to where the pressure is lower
Factors that affect the draft force in the air ducts:
- Temperature difference between extract air and outdoor air
In winter, cravings are stronger because the warm room air tends upward along the exhaust ducts. In summer, there is no temperature difference, the draft is zero - and the air exchange practically stops. - Vertical distance between room and roof
Above, the pressure is lower than at the surface of the earth. Therefore, the higher the exhaust duct ends, the greater the pressure drop. This means that the cravings are stronger. - Wind speed and direction
The wind appears when Atmosphere pressure distributed unevenly. If there is a zone of increased pressure in the area of \ u200b \ u200bthe windows, and at the exit from chimney there is a zone of reduced pressure, then the air will easily enter the house and easily leave.
Neither the wind, nor the pressure, nor the temperature outside the window, we can control. This is the main disadvantage of natural ventilation - dependence on weather conditions.
But there are several tricks that will help you to correctly make natural ventilation in a private house with your own hands. Some of them can be applied only at the design stage, others - even in a newly built house with a final renovation.
WHAT IS VENTILATION AND WHAT IS IT NEEDED FOR?
HOW TO CHECK PERFORMANCE?
HOW NOT TO STAY OUT OF AIR?
A LITTLE ABOUT THINNES ...
THE "FAMOUS" PROBLEM OF THE LAST FLOORS
THE MOST COMMON DELUSION
WHY "SUDDENLY" THE VENTILATION STOPPED TO WORK?
WHAT IS VENTILATION AND WHAT IS IT NEEDED FOR?
According to existing standards, each living space (apartment) must be equipped with ventilation, which serves to remove polluted air from non-residential areas of the apartment (kitchen, bathroom, toilet). Ventilation is air movement, air exchange. Each person breathes during the day, uses the stove, does laundry or wash, goes to the toilet, many smoke. All these actions contribute to air pollution in the apartment and its excessive saturation with moisture. If the ventilation is working properly, then we do not notice all this, but if its performance is impaired, then it pours into big problem for those living in such an apartment, the glasses on the windows begin to fog up and condensation flows down onto the windowsill and the wall; damp the corners, and mold appears on the walls and ceiling; the laundry dries in the bathroom for 2-3 days, and when using the toilet, the smell spreads throughout the apartment. Plus, if there is a baby or a very small child in an apartment without ventilation, then, sometimes, one or two years of being in such conditions is enough for him to develop bronchial asthma or other respiratory diseases.
In order to find out whether the ventilation is working or not, you do not need to be a specialist. Take a small piece of toilet paper. Open a window (window) in any room and bring the prepared piece of toilet paper to the ventilation grill in the bathroom, kitchen or toilet. If the leaf is attracted, the ventilation works. If the leaf does not stick to the grate and falls, the ventilation does not work. If the leaf does not attract, but rather deviates from the ventilation grill, it means that you have reverse draft and you breathe foreign odors, which means that the ventilation does not work.
HOW TO CHECK PERFORMANCE?
Ventilation can be checked or measured. It is measured with a special device - an anemometer. This device shows at what speed the air moves in the ventilation duct. Having in your hands a calculation table, you can substitute in it the values of the anemometer and the cross-section of your ventilation grill and you will receive a figure that will tell you how many cubic meters of air in one hour (m³ / h) passes through the ventilation grill. But that's not all. When checking, there are many conditions that cannot be ignored, otherwise the measured data will be incorrect.
According to the "Methodology for testing air exchange in residential buildings", measurements are carried out with a temperature difference between indoor and outdoor air = 13 ° C (example: outside + 5 ° C; in an apartment + 18 ° C), and at the same time outside the air temperature should not be higher than + 5 ° C.
The fact is that in the warm season, ventilation works worse and nothing can be done about it, because such are the laws of physics on this planet. If you measure ventilation at a temperature warmer than + 5 ° C, then the obtained measurement data will be incorrect. And the warmer the outside air temperature, the further the measurement data will be from the normative ones. In extreme heat, in some cases, even completely serviceable ventilation may stop working or even work in the opposite direction (reverse draft).
To understand why this is happening, you need to remember what each of us heard at school in physics lessons. The lower the temperature, the higher the density of the air, that is, the heavier the air. Therefore, the highest air density in winter is in frosty weather, and the lowest in summer.
Therefore, if in an apartment, for example, the temperature is + 18 ° C, and outside it is -3 ° C, then the warmer (lighter) internal air through the ventilation duct will tend to move from the apartment to the street. As the outside temperature rises, the specific gravity of the outside and inside air will begin to level out, which means that the draft in the duct will begin to weaken. And if the temperature in the apartment is, for example, + 24 ° C, and the heat outside is at + 30 ° C, then the cooler (heavier) internal air will simply not be able to rise up and exit through the ventilation duct into the atmosphere. It will be much easier for him to move not up, but down, that is, as if "flowing" out of the apartment.
That is why, in hot weather, there is a high probability that ventilation can give a reverse draft, although it cannot be recognized as faulty, since under these conditions, according to the laws of Nature, it could not work.
So, ventilation can be measured only if it is working. But first you need to find out if it works.
As already mentioned, anyone can do this - it doesn't take much effort. This requires a small piece of toilet paper. No need to take a sheet of newspaper, magazine or cardboard. Why?? According to the existing standards for a kitchen (with an electric stove), a bathroom and a toilet: 60, 25 and 25 m³ / h, respectively. To achieve these values, a relatively low speed of air movement through the ventilation grate is required and such movement can only be detected with a thin sheet of paper (better if it is toilet paper). In some apartments, a piece of thick, heavy paper sometimes attracts, but this suggests that in this apartment the ventilation works so well that it exceeds the required norm. There is one more thing to consider here. necessary condition check traction. According to the same "Test Methodology for Air Exchange in Residential Buildings", when checking ventilation, in one of the rooms the sash of the window is slightly opened by 5 - 8 cm and the doors are opened between this room and the kitchen or bathroom.
We happened to be present at many commissions that met to assess the state of ventilation in various apartments and, sometimes, we had to observe how a representative of the inspecting organization checked ventilation during closed window... This is mistake!! In our country, ventilation in residential premises is a supply and exhaust ventilation with a natural impulse, that is, not forced, not mechanical. And all air exchange rates were calculated specifically for natural ventilation. And in order for the air to go into the ventilation grill, it must come from somewhere, and, according to the norms, it must come (enter) the apartment through the cracks in windows, doors and other structures. In the early 90s, unprecedented hitherto unseen plastic windows with sealed double-glazed windows and metal doors with seals. Undoubtedly, these products are not like our old ones. wooden windows with their eternal drafts, but here one problem arose - new technologies came, but the norms remained old and, according to these norms, the air flow into the apartment is carried out through cracks and leaks, and new double-glazed windows completely exclude these leaks. So it turns out that sealed windows and doors create conditions in the apartment under which ventilation cannot work normally. And then, feeling the lack of fresh air in the apartment, people come up with another problem for themselves - they install fans.
HOW NOT TO STAY OUT OF AIR?
Let's outline a situation that we often encountered. So, let's take the usual two-room apartment("Khrushchev") with a total area of 53 m². This apartment has a metal door with a seal and plastic windows. There are also two ventilation ducts - one for the s / node, and the other for the kitchen and a "hood" above the stove is brought into the kitchen ventilation duct (one might say a classic situation). Now "hoods" (that is, the hood above the stove) are so powerful that at the maximum working position their capacity according to the passport is 1000 m³ / h and even more. Now imagine that in such a sealed room, the hostess decided to cook something and turned on the "hood" above the stove at full power. With a ceiling height of 2 m. 60 cm, the air volume in this apartment is only 138 m³. For the hood, by definition, it will take quite a bit of time to "swallow", let through the cubic meters of air in this apartment. As a result, the "hood" begins to pump air out of the apartment and creates a vacuum, and since the windows and doors are very dense and air does not flow through them for circulation, there is only one place left through which air can flow into the apartment - air vent s / node (!!!). In such a situation, even a normally working ventilation from / node (toilet and bathroom) will start working in the opposite direction (reverse draft). And, since ventilation within the attic is integrated into common system, then the apartment begins to receive odors from other floors, sometimes obscenely fetid.
In this case, the solution to the problem with reverse draft is quite simple - to open the windows at the time of using the hood. Since you have decided to connect your life with sealed double-glazed windows and the same sealed door, then you will have to come to terms with the fact that the air flow into your apartment will be carried out through an open window - there is no other way. The supply units are able to compensate for the air removed through the standard ventilation ducts, but providing a powerful exhaust air with air is a difficult task for them.
A LITTLE ABOUT THINNES ...
Not a very common problem. However, if you do not know about it, then you can look for the cause of the reverse thrust for a very long time and find nothing. So, there is a reverse thrust in the ventilation channel, but during the examination it turns out that the channel is absolutely clean, in the attic the horizontal connecting boxes (if any) are in perfect order, and the shaft that goes out to the roof is also normal and there is simply nothing to complain about. It turns out that the reason for the "return" is that the ventilation grill is installed on the "through" channel. That is, two or more apartments are connected to one channel (vertically).
For normal work ventilation, the ventilation duct of the apartment must begin with a "plug", that is, the air entering through the ventilation grill into the duct should have only one way - upward. In no case should there be a downward movement - either immediately at the bottom of the vent grating, or with a small depression, but the channel must be muffled (blocked) in its lower part. Otherwise, there is a high probability that such a channel will give back thrust.
For the most part, this problem is faced by people living in houses of the II-18 and I-209A series. These are 14, 12-storey one-way "towers". However, a similar ventilation system is used in 9-storey panel houses and in some brick houses, if the ventilation is not lined with bricks, but mounted with whole concrete panels with channels cast inside.
This system looks like this. There is a collection channel (common shaft) with a diameter of about 220-240 mm, and satellite channels with a diameter of about 130-150 mm are located on the sides of the collection channel. Usually apartments are connected to such a ventilation system "at a run" - for example, the 1st floor to the left of the mine satellite channel, the 2nd floor to the right, the 3rd floor to the left, etc. Vent blocks are cast at the precast concrete plant in such a way that the satellite channels (they are also the accelerating sections) communicate with the common shaft with windows every 2.5 meters. That is, the air must get from the apartment into the vent-lattice, rise along the satellite channel up by 2.5 meters, rest against the "plug" and exit through the window into the common shaft (collecting channel). But that's the whole trouble, there are NO "plugs" in these houses.
Most likely, the designer provided for the so-called “universal” ventilation unit. The fact is that if you cast ventilation blocks at the factory with a division into "right" and "left" or "for even floors" and "for odd", then during their installation, confusion is inevitable and problems are guaranteed. Therefore, the ventilation block was made universal, so that during installation the worker would put it without thinking about its geometry. And after installation, he chose which satellite channel would be used for the “even” floors of the house, and which one for the “odd” ones, and, based on this, the installer had to install plugs in the satellite channels on the spot.
The designer's faith in the conscientiousness of our builders while observing technological process is truly naive. I myself have worked at a construction site for many years and I know how our apartments are built.
The result is the following. Instead of a ventilation system with a common (transit) shaft and two satellite channels, we have three transit channels in our houses. On the lower floors, this problem is not yet so noticeable, but on the upper floors, if the ventilation grill is installed on such a transit channel, then you should not be surprised at the odors in the apartment. The air flow, rising along the channel and flying past the ventilation grill, will either give back draft, or will strongly impede the removal of air from the apartment. And, if you install a plug, then it will cut off the lower air flow and direct it into the collection channel through the provided window. Thus, ventilation in the apartment begins as if from scratch - without experiencing any obstacles and not burdened with the struggle with other air flows, that is, as it should be.
THE "FAMOUS" PROBLEM OF THE LAST FLOORS
Sometimes, when people turned to us for help, and when describing their problem, they said that they had the last floor in the house, this was enough to establish the reason for the lack of normal ventilation without leaving the place. Then it only remained to go to the place and confirm their assumptions. Believe me, a huge number of people, thousands, suffer from this problem. The fact is that for normal ventilation in an apartment, it is advisable for air to pass through the ventilation channel at least about 2 meters vertically. On any other floor, this is possible, but on the last such a possibility is excluded - the attic is an obstacle. There are three ways to bring ventilation from the apartment to the street. The first is that the ventilation ducts go directly to the roof in the form of a pipe head. Almost all houses were built in this way until the beginning of the twentieth century, and then they gradually began to move away from this method. The reason is that the number of storeys in buildings has increased. We are not interested in this method, because there have almost never been any problems with it. The second method - ventilation, reaching the attic, was covered with horizontal sealed boxes, which were connected to a shaft that went out over the roof. The third method (modern) - ventilation first enters the attic, which serves as a kind of intermediate ventilation chamber, and only after that it comes out through one common ventilation shaft.
We are interested in the second and third options. In the second case, the following happens - air through the channels from all floors rises up to the level of the attic and bursts into the horizontal junction box mounted in the attic. In this case, the air flow hits the cover of the horizontal ventilation box. The air flow deviates slightly towards the ventilation shaft, but if the internal section of the horizontal attic duct is insufficient, then an area of increased pressure arises in the duct and the air seeks to find an outlet to any nearest opening. There are usually two such exits (holes) - the ventilation shaft intended for this and the channel of the upper floor, since it is the closest one and is located almost in the box at a distance of only 40-60 cm. reverse side. If the cross-section of the box in the attic is sufficient, but the lid is mounted too low, then the same thing happens - reverse thrust - the air flow, due to the small height of the lid, does not have time to deviate towards the ventilation shaft and an impact occurs. The reflected air flow "pushes" the ventilation of the upper floor and all odors from the lower floors enter this apartment. There are two ways to deal with this - global and local. Global - to increase the cross-section of the attic horizontal junction box by changing its height 2 - 3 times, plus the device inside the box of "tricky" devices, which we call "incisions". But, firstly, specialists should do this, and secondly, it is not recommended to increase the section of the duct if the same ducts are connected to the ventilation shaft from the opposite side. The local method consists in the fact that the channels of the upper floor are separated from the general air flow and are separately brought into the shaft on top of the box. These individual channels are insulated so as not to violate the temperature and humidity regime (TVR) of the attic. And that's all - the ventilation in the apartment is working.
Now for the third (modern) air removal option. According to this principle, ventilation works in all high-rise buildings (series: P - 44, P3M, KOPE, etc.). The last floors in such houses often suffer not from reverse thrust, but from a weakened one. Instead of passing the 2 meters vertically laid down according to the norms and then connecting with the general flow, the following happens on the last floors - the air, entering the channel, passes only about 30 centimeters vertically and, not having time to gain strength and speed, dissipates. Ventilation does not disappear in this way, but air exchange in the upper apartment is greatly reduced. If the entrance and intersectional doors of the attic are open (this is often the case), then a strong draft arises that can "overturn" the draft in the apartments of the upper floor. To prevent this from happening, the individual channels of the upper floor must be increased. The diameter of these channels is 140 mm. It is necessary to put pipes of the same diameter on these holes, and carefully coat the joints with alabaster. Lead the pipes to a height of about 1 meter and tilt them slightly towards the common shaft so that the air flow rising from below, flying next to the output pipes, picks up and draws the air from the channels of the upper floor with the force of its flow.
THE MOST COMMON DELUSION
Each of us has a kitchen in our apartment. Everyone has a stove in the kitchen (gas or electric). And the overwhelming majority have an exhaust "umbrella" above the stove (in the common people - "exhaust"). What is the delusion ?? In what many people consider to be "hood" the equivalent of ventilation in the kitchen. Otherwise, how to explain the fact that, by installing the hood above the stove, the air duct from it is led into the ventilation hole of the kitchen, closing it completely ??
They do this for several reasons - either the builders who made the repairs advised, or from the complete confidence that even so, the air from the kitchen is perfectly removed. Plus, the hood sellers claim that the power of the hood you buy should be selected taking into account the area of the kitchen. In fact, all this is delusion.
Let's try to figure out where it came from. If you carefully read the various regulatory documents for construction and operation, then a strange pattern can be traced: IN ANY document you will not come across the word ... EXTRACT!
Note: 1) it is about regulatory documents rather than reference; 2) extractor hood - kitchen hood (noun), not extractor hood - as an action (verb).
So, if in regulatory framework there is no such thing as a hood, then how can air exchange be normalized with its help ??? Nonsense.
Then the end users of hoods have a reasonable question: how is it that hoods exist, but there is no word? And everything is very simple, there is a word and extracts, only they are, as it were, "outside the law." And this is due to the fact that ALL residential buildings (99.99%) in Russia (and the former USSR) have natural ventilation, or, more correctly, ventilation with natural urge.
Those. air enters our apartments through leaks in windows, doors and building structures, as well as through special supply valves or ducts, and leaves through ventilation ducts located in the kitchen, bathroom, toilet.
How is this related? Let's try to explain. Any building structures or communications are designed for certain loads. Ventilation is no exception to this list. Our channels have rather limited bandwidth capabilities. V best conditions their capacity is 150 - 180 m3 / h (for comparison: modern hoods have a capacity of 600-1100 m3 / h)
Sorry if we took a long time from you. So we come to delusions. The fact is that there are also standards for mechanical ventilation, which differ significantly from the standards for natural ventilation. For example, air exchange for a kitchen with natural ventilation should be 3 times, and with mechanical ventilation - 10-12 times. So, the sellers of the hoods apply the norm (10-12 times), without thinking that the hood over the stove and the norms of mechanical ventilation are in no way connected with each other and the hood over the stove has NO RELATIONSHIP TO VENTILATION of the premises.
The hood is not suitable for ventilation in the kitchen. It is only for removing polluted air in a small space above the stove. The hood is not able to cope with the air that has risen to the ceiling better than a conventional ventilation duct in the upper part of the room. To “reach” this air for the hood is an almost impossible task. The fact is that the behavior of the air flow during intake and discharge is different. During suction, air is taken in from a distance of no more than one diameter of the suction inlet, and the air jet is thrown out to a distance of fifteen diameters of the inlet. That is why we vacuum the carpet not from a height of a meter, but by pressing the brush. That is why, in the heat, we direct the fan towards ourselves with the front side, and not with the back. That is why the hood cannot “take” the polluted air (odors) that has risen to the ceiling.
The hood during operation removes air above the stove and nearby. Thus, air movement in the room is created, and additional air flows are involved in the mixing process. How much is pumped out of the room, the same amount is received for replacement. If the hood has pumped 1000 cubic meters of air, this does not mean at all that the air in the room has been completely renewed several times. The resulting emptiness, which Nature does not like, will be filled with air that came from anywhere - from a window, from other rooms, from cracks. But cooking odors that have risen to the ceiling do not mix well and are difficult to remove. It is not for nothing that the instructions for the hoods say that ... “... in order to maximize the efficiency of the work, the hood should be located 60 cm from the electric stove and 75 cm from gas stove... ". "... When the hood is in operation, avoid air currents - this can cause odors to spread throughout the room." If the hood was designed to ventilate the kitchen, then the instructions would not contain such recommendations, and the hood itself would be advised to be installed at the top, instead of a chandelier.
By the way, in the instructions for the hoods there is no mention of how much room it is designed for. This has already been invented by the sellers of this product themselves. The area of the room does NOT AFFECT performance. Conversely, the power of the purchased hood does not depend on the size of the room.
The main factor affecting the performance of the hood is the cross-section of the ventilation ducts in our homes. The overwhelming majority of channels in our country have a cross section of 130 x 130 mm, or a diameter of 140 mm. By attaching mechanical (forced) ventilation to such a small channel, we get a miserable effect. More air than such a channel can still not let through, no matter how hard you try. In almost any manual for a fan or hood, a diagram is drawn that shows a performance versus pressure curve, from which it is clear that the higher the pressure, the lower the performance of the hood or fan. The main factors due to which there is an increase in pressure in the channel and, as a consequence, a drop in productivity are: unevenness inside the channel; displacement of floor blocks; protruding solution; narrowed section; material and shape of connecting ducts; every turn in the path of the air flow.
As a result, due to the influence of these factors, increased pressure will be created in the channel and on the approach to it, and, as you know, the higher the pressure, the lower the extraction performance. This means that the POWERFUL range hood suffocates itself. And the more powerful the hood, the more it "locks" itself.
You can connect a hood with a capacity of 1000 m3 / h, 1500 m3 / h is possible, 5000 m3 / h (if there is one), but in all cases the result will be the same - it will be possible to push a slightly larger volume of air into the channel and that's it !!! The rest is losses !!!
Once on one of the connections of the hood to a ventilation duct with a diameter of 140 mm, in the P-44 series, we specially took with us a cup anemometer for measurements. When almost everything was mounted, we asked the client for permission to experiment a little. The air duct was disconnected and a pre-prepared insert with an anemometer was installed. Four-speed hood "SATA". Centrifugal fan. The length of the duct is 3.5 meters with two bends. The air duct is plastic, with a diameter of 125 mm. The maximum capacity of the exhaust dome is 1020 m3 / h. The anemometer was installed before the last turn (at the very entrance to the ventilation block). The first speed - the anemometer showed 250 cubic meters / hour. The second speed - readings of 340 cubic meters / hour. The third speed is readings of 400 cubic meters / hour. The fourth speed is 400 cubic meters / hour. Bottom line: 1) the difference in performance between the first and fourth speeds is minimal; 2) the channel missed EVERYTHING it could, which means that the losses are simply enormous; 3) the noise at the third and fourth speeds has increased, but there is zero sense. And this despite the fact that the walls of the connecting air ducts and the ventilation duct are very smooth !!! Imagine what the performance loss will be if you connect the hood to a ventilation duct, which is made, say, in brickwork !!!
Of course, you can use the hood as a simple fan, but in this case you shouldn't hope that it will provide you with a full air exchange. We do not dissuade you from purchasing a cooker hood at all and do not claim that it is not a necessary and useless thing. Of course it is not. The only goal we pursue is the desire to warn the consumer against common delusion. Namely: 1) you should not take an exhaust hood in the kitchen as the equivalent of room ventilation - it has nothing to do with this; 2) when buying a cooker hood, you cannot build on the size of the room - these are unrelated things.
WHY "SUDDENLY" THE VENTILATION STOPPED TO WORK?
It happens. She seemed to have worked, worked for many years and "suddenly" stopped. Many tenants are inclined to believe that the reason for this is the neighbors, who climbed into the ventilation riser and blocked something there. Of course, there are also such "craftsmen". These "specialists" are well aware that according to electrical network current flows, through the sewers - poop, through pipes - water, but when it comes to ventilation - logic refuses them - they cannot understand that there is not a void that needs to be occupied, there is air moving.
But it's not about them. If we immediately cut off all cases when neighbors really violated ventilation and try to figure out the other reasons that influenced its performance, it turns out that tenants create a huge number of problems with ventilation themselves.
How does this happen? For example, let's take the most common modern scheme of natural ventilation: a) a multi-storey building, b) the ventilation of the house goes to a warm attic and consists of a collection channel (common shaft) and a satellite channel. This scheme is suitable for houses of the series: P-44, P-3M, KOPE, P-46, P-55, P-30, P-42, P-43, some monolithic houses and many less common series.
Ventilation in these houses consists of a collecting duct (common shaft), which goes in transit from the ground floor to the attic. In addition, for each apartment there is an individual channel (satellite channel), which starts from the ventilation grill in the apartment, then rises one floor and, before reaching the same individual channel of the above apartment, goes out through the hole into the common shaft, where the air continues your movement to the attic and further to the street.
To make it easier to understand this scheme, imagine a full-flowing river with small rivulets flowing into it. This is the ventilation scheme under consideration. The river is a collecting mine; the streams flowing into it are satellite channels.
As tributaries feed a deep river, satellite canals fill the collection shaft with air. If you begin to block the tributaries, the river will become shallow and dry up. If air does not escape from the satellite channels, then the speed and volume of air in the collecting shaft will significantly decrease. Since the ventilation system of a house is a chain of interconnected and interdependent links, the violation of one of the links leads to changes in the entire chain, which ultimately turns into problems for the entire ventilation system of the riser, the entrance, and sometimes the house.
You can trace all the stages of the violation of the ventilation system.
An ordinary 17-storey panel house, of which there are plenty of them all the time. The ventilation scheme used in these houses is perhaps the best that a person has invented for residential high-rise buildings. This ventilation system is capable of operating even in extreme heat. Although, by definition, it shouldn't work in the summer. In the heat, ventilation according to all conditions and rules must stop or overturn (reverse draft). But this does not happen in these houses, because the ventilation duct, which is the prefabricated shaft, has a height of about 50 meters. And due to such a difference in height, and hence a difference in pressure difference between the lower and upper points, a fairly strong air flow (thrust) arises. The strengthening factor here is the "warm attic". And even a strong heat is not able to "interrupt" this bundle. BUT ... only if the ventilation system has the conditions it needs to work.
One entrance of any multi-entrance building with a warm attic is a closed and isolated system. Ventilation of any apartment in this entrance is an integral part of this system. That is, the ventilation of each apartment depends on the other apartments in the entrance and, conversely, each apartment affects all other apartments.
The influence of one apartment on its riser or the entire entrance is insignificant and is not able to change the “balance of power”. But this is if one apartment. And if there are several of them ?? If there are five, or ten, or twenty, or half. And if more than half? That is, if there are apartments that do not participate in the system (fall out of it), then this system loses strength, weakens. There is a certain tipping point after which it fails. That is, the sum of all air currents going into the attic turns out to be insufficient to push this air out of the attic into the atmosphere. Because the common exhaust shaft, which goes from the attic to the roof (to the street), is quite impressive in size. And this breakthrough "wants to eat", that is, its dimensions are designed for the passage of a certain volume of air, which it does not receive. There is a saying: "You cannot warm the sea with an awl." This is just our case. As a result, the speed and density of the air flow in such a shaft decreases and the thrust is overturned. More "heavy" in winter cold air falls, and the outgoing warm air flow ("awl") is too small for the large size of the mine ("sea").
A reasonable question arises: “Why is the volume of air discharged through the ventilation mine into the atmosphere decreasing? What is the reason?".
The answer can be obtained using the example of the smallest link in the general ventilation system - for example, the ventilation of a single apartment.
The apartment has two ventilation ducts. One works for the kitchen, the other for the bathroom (bathroom + toilet). Two ducts remove air from the apartment for ventilation 24 hours a day. The removed dirty, humid, exhaust air should be replaced by another air - outside, fresh, oxygen-enriched. That is, the SUPPLY. Thanks to this circulation, this constant replacement (inflow), normal living conditions are maintained in the apartment.
Only the inflow of outside air can be considered a normal, full-fledged inflow. The air that came from staircase through the cracks in the front door or coming from the next room (apartment), in quality nothing better than that air that is already available in the apartment. It is just as dirty, wet, it has already been smoked, puffed with toilet freshener and saturated with the "aromas" of the kitchen. It's like an old joke about a concentration camp: “Today there will be a change of linen. The first barrack changes with the second. "
Previously, the influx into the apartment was mainly carried out through cracks and leaks in our old, terrible, crooked, leaky windows. When these shameful windows are replaced with new sealed double-glazed windows, the previous order of air circulation is disrupted. The new windows are very dense, there are practically no cracks in them, which means that the flow of outside air through them is almost zero. Temporary opening of vents and sashes is self-deception. Ventilation works constantly, which means that the demand for inflow is also constant.
Has anyone tried to pump air out of a plastic bottle ?? Right. It's impossible. And if you make a hole in the bottle ?? Then you can pump air out of the bottle ad infinitum. The hole is the inflow. The bottle is an apartment with sealed double-glazed windows. When the windows are closed, ventilation cannot work normally. Under these conditions, only two things can happen to her:
a) one of the ventilation channels of the apartment (stronger channel) will begin to drag the other channel. That is, the second, weaker channel will begin to perform the function of an inflow, which was ruined by the installation of new windows;
b) both ventilation channels will work as before, and the missing inflow will be compensated through the gaps between other apartments. That is, they will suck in the apartment exactly the same exhaust air that is removed, only with other people's smells.
So it turns out that: in one case, instead of two normally working channels of an apartment, we have only one working channel. This means that the volume of air removed from one apartment has decreased by at least half (!!!). In the second case, the channels seem to fill the prefabricated shaft with air, but this is the air inside the house, and not outside. This means that the channels do not work for the apartment in which they are located and the air circulation in this apartment is disrupted.
Now go outside, look at any house, select any riser of apartments and count how many old windows are left along the entire vertical, and how much plastic ones cost. Those with plastic can be deleted from the general ventilation system of the entrance. This is ballast. Without an inflow, these apartments hang with weights on the legs of the ventilation system. And if in summer or winter (less often in winter) from your ventilation channels "suddenly" there is a reverse draft, then you can safely say "thank you very much" to these neighbors. They tried very hard.
The main conclusion.
You cannot mindlessly install sealed double-glazed windows. These windows are not on their own. They are part of the ventilation system. It depends on you whether the ventilation will work or not. Have you decided to install sealed double-glazed windows ?? Organize a CONSTANT FLOW !!!.
As you know, kitchen hoods are classic and recirculating. The first diverts air into ventilation shaft or straight to the street.
The recirculation simply drives it through itself, trapping the fat. In its design, it has filters to clean the air from odors.
The main questions and problems arise during the installation and connection of the classic version. We will consider it in as much detail as possible.
To begin with, we will briefly list the main mistakes that lie in wait for you along the way. Below are the ways to solve them and the most popular installation methods.
Errors when installing a kitchen hood
1 Blind connection of the duct to natural ventilation is the most common mistake.
Some people, of course, leave the grate for the natural movement of air, but they still manage to block it with the air duct itself. 
3 Output of the duct to the street through a self-made hole in the wall. 
In most cases, this is prohibited by the rules. Specific points will be listed below.
You can, of course, lay a separate box along the facade right up to the roof. But is it worth it? Although in restaurants and cafes located on the ground floors of high-rise buildings, this solution is widely used. 
By the way, the ban on air outlet through the wall does not apply to private houses, but only to high-rise buildings.
4 Complex track geometry with large quantity transitions and curvatures.
This will primarily affect the noise. Although, of course, the turns themselves are not the greatest evil. And sometimes you can't do without them. 
It is the turns that are dangerous, going one after the other, without accelerating sections.
5 Connecting a too powerful hood (for example 1000 m3 / h) to a standard ventilation duct, which is capable of passing about 300 m3 / h.
Remember that a capacity of 200-300 m3 / h is quite enough for a high-quality removal of all odors, with a minimum load on the ventilation of the house.
6 Installing the hood at the wrong height.
The installation height directly depends on what kind of stove you have - gas or induction cooking. 
Believe me, sometimes this structure has to be disassembled.
8 The upper, not the lower, location of the slots in the decorative grille in the same frame with the air duct.
Why this is a mistake, and when it is still possible to do so, is discussed further.
9 Lack of a separate outlet in the upper part of the wall for the hood.
As a result, connecting it haphazardly, through carriers and extension cords. Do not forget that in the end it is still not a portable device, such as a fan, heater or mobile air conditioner. 
So the wiring for it needs to be done stationary and wisely.
10 Incorrect installation of the non-return valve.
It must be cut in and installed in compliance with the appropriate angles and slopes. Otherwise, it will work through time.
In general, the installation of the hood can be divided into two main stages. The first is its electrical connection. The second is the duct device and everything connected with it.
Let's take a look at each of them separately.
Connecting the hood to electricity
This stage is the simplest. It is very good when you initially planning your kitchen, correctly laid the location of all sockets and electric outlets. 
How not to make a bunch of elementary mistakes and observe all distances, you can find in a separate article. 
If you do not have a free outlet for the hood, you will have to mount it. To do this, you will need the following materials:
V home wiring use the cable of this particular brand (with the Ls index). 
- regular socket for current 16A with grounding contacts
The hood itself, unlike other kitchen appliances, is a low-power device. Accordingly, it is not at all necessary to pull a separate wiring under it directly from the control room.
The same cannot be said about the hob or dishwasher. 
It turns out that this unit can be connected from a common outlet group from the nearest distribution box. 
Pull the strobe or cable channel from the junction box to the place of the future outlet and mount the socket box. 
This outlet is located on top, almost under the ceiling, just above or to the side of the hood itself. The choice of a specific location will depend on the length of the cord and the requirement for a minimum installation height of the hood above the hob. 
Often you have to cut a hole in the nearest kitchen cabinet for this case. 
Next, you remove the insulation from the cable, mark the cores and connect them together in the junction box. 
All that remains is to connect the outlet correctly. 
You have the wiring for the kitchen unit ready. We pass to the duct.
Incorrect connection of the exhaust duct to the ventilation
The main problem during installation is to correctly connect the air duct and at the same time not to disturb the natural ventilation in the apartment.
Some of the craftsmen generally advise to take the whole thing out onto the street, through the nearest wall. However, according to SNiP, it is forbidden to do so. 
It clearly states that such a hole cannot be placed closer than 8m from the adjacent window. Since this window is considered an outdoor air supply device.
Here, check out the points of the set of rules SP54 and SP60. 
That is, drill a healthy hole in the wall, spend a lot of nerves and money, and the neighbor will complain about you, and you will be OBLIGED to repair it all.
How do most consumers connect? An ordinary corrugation is taken, pushed onto the outlet, stretched and attached to the flange, which is screwed to the ventilation hole. 
That's all. Simple, cheap and wrong. What are the disadvantages of this method? First, the noise.
When air passes through such a ribbed corrugation, it emits extremely unpleasant sounds.
But most importantly, when your device is turned off and does not work, natural ventilation is forced to draw air from the apartment through the hood. Not only can your box be clogged, but in the summer, traction is sometimes not observed at all (due to the same temperature at home and outside). 
Moreover, you actually place an oily mesh, motor, turbine, etc. in the path of the air. And also, the air will be sucked in not at the ceiling level, but at the level of the middle of the kitchen.
Although the collection of all odors of waste products, just the same should be carried out from the maximum height.
It is quite clear that there will be no thrust in this case. That is, you are depriving yourself of natural ventilation with your own hands.
This threatens the appearance of a fungus, high humidity... In the offseason, your doors will simply begin to swell and poorly close. 
And also there will be a deficiency of oxygen and constantly feeling unwell. At the same time, someone strikes into mysticism and begins to think that they have been damaged or an apartment with poor energy, but in fact, there it is - improper ventilation!
Initially, in Soviet times, when designing our multi-storey buildings, the engineers expected that air would flow into the apartment, among other things, due to leaks in the wooden windows.
However, with the installation plastic windows and sealed doors, we have thereby blocked this channel of fresh air in the house. Close the ventilation as well and you will live like in a submarine.
To remedy the situation in such cases, it is recommended to install the supply valve on a plastic window. 
Instead of clogging, you can do everything more intelligently. What alternatives are used for this?
Exhaust air duct and grill with non-return valve
First, instead of a corrugation, a plastic pipe is taken (for example, d-125mm), and through one or several elbows it is brought out into the hole of the ventilation duct. At the same time, a kind of separation is made in the hole itself under the ceiling.
Above, an entry under the pipe is mounted, and a small rectangle is left from below through a grate with a valve for a natural inflow. 
Moreover, the lattice should be just below, and not above. Otherwise, the air flow from the hood will blow up and raise the so-called check valve. 
Although, of course, if you have a more perfect valve design - a circle or a rectangle with an offset axis, and not simple strips of polyethylene, or there is a one-piece partition, then you can safely put it as you want - from above, from the side, from below.
However, in fact, this whole design often does not work as intended. When you turn on the exhaust unit and create pressure, a small part of the dust still seeps through the cracks, micro-holes, after which it safely gets to your kitchen on the dining table.
None check valves do not save 100%. The bulk of the air, of course, goes outside, but the gradual formation of dust inside the apartment is a fact. 
And even when the hood is turned off due to a decrease in the diameter of the original hole, natural ventilation through narrow grilles will be several times worse.
Everything can be done much better.
Correct connection of the duct to the ventilation system
To do this, you will need:
You should end up with something like this. 
How does it all work? When the hood is off, the valve will be open and warm air from the kitchen will calmly flow by gravity into the ventilation duct. As soon as you turn on the hood, the valve immediately closes automatically, blocking the flow of air into the room. 
In this case, all the smells from the stove will calmly go out into the street. When disconnected, the pressure in the box drops and the valve leans back on its own, connecting the ventilation shaft to the apartment.
Assembly instruction - all numbers and performance
How is it all going in practice? For capacities up to 300 m3 / h (low speeds of most hoods), a d-125mm pipe is enough. On the device itself, the outlet can be large.
For example, for 650 m3 / h you will need a d-150mm pipe. However, you are unlikely to find such plastic pipes, and if you use the following standard size d-160mm, then it will turn out to be a huge and awkward structure, spoiling the entire interior and design of the kitchen.
Moreover, you will have to hammer the factory hole of the ventilation duct in the wall, expanding it. 
Therefore, in most cases, they choose optimal diameter in 125mm. And you don't need more.
The forced throughput of standard channels and shafts with dimensions of 100 * 150mm is 400 m3 / h. 
An air flow of more than 450 m3 / h will simply not fit there (it has been tested in practice), even if your hood says - 1200 m3 / h!
Remember also that it is impossible to underestimate the diameter of the air duct in comparison with the outlet pipe on the hood. Otherwise, the vibration and noise will be so strong that the structure will have to be glued again every month.
Compound different diameters done with special adapters. 
Let's start assembling. First, install the adapter on the hood and connect the vertical section to it. 
To improve its sound insulation, it makes sense to get confused and stick on top of a heat-sound insulating material 5mm thick. 
It will not hurt them to glue the decorative casing and the noisiest part - the adapter from the inside. It is there that the most turbulence is observed. 
All this is glued with silicone, no superglues. There should be no cracks anywhere. 
We reach the tee. A valve is installed into it from the side of the room. 
Note that this is a gravity operated valve! It does not open due to the flow of air, but due to its weight.
It has one half heavier than the other and at the same time it is installed at a slight angle of 2 degrees. 
Preparation of the ventilation shaft opening
It is advisable to plaster the entry into the ventilation shaft itself before all installation work and remove all sharp corners. This will give the entrance maximum aerodynamic qualities. 
You should end up with roughly the same surface as a standard 90 degree round bend.
It is advised to add ceresit liquid (ceresit CT99) to the plaster solution. 
This hole will be exposed to grease and moisture. And ceresite contains components that prevent the formation of mold.
In this case, do not use gypsum plaster under any circumstances. Its use in ventilation shafts is a direct path to the appearance of this very mold and mildew. 
On both sides of the tee, connect standard air duct pieces. From the side of the wall, brick it up by 5-7 cm into the ventilation duct. Ennoble the exit itself with a square frame. 
Why the check valve sometimes does not work and does not close
A check valve is mounted on the tee from the side of the kitchen. In the factory version, it will be quite long. In this case, it is better to shorten it so that this "gun" does not stick out too much. 
The valve is inserted into a section of a standard d-125mm duct, and this duct is already put on and silicone onto the tee.
If this whole structure seemed too cumbersome to you, and the protruding pipe with a valve is not very aesthetic, you can do it a little differently. Do not air duct round pipe, and rectangular channels.
In this case, the above-mentioned check valve is cut in a straight section, as close as possible to the turn. 
Factory connection cannot be achieved here, so collective farms will have to be used. A rectangular tee with a round outlet on one side is purchased.
Further, this round timber is cut off and a check valve is glued in its place.
The valve is placed strictly at an angle (2 degrees). Otherwise, it will open for you every other time or not open at all.
Many have come across this problem and easily solved it in this way.
The damper itself is also mounted vertically. The upper turning point, based on the hour dial, is at 13:00 (1 o'clock), and the lower one at 17:00 (5 o'clock). This is if you have a right-to-left flow direction. 
Otherwise, the circle is placed at the 11 o'clock - 7 o'clock position.
For more reliable operation and stable opening of the damper, you can stick a certain weighting agent on one of the sides (no more than 2 grams). Stick it close to the edge. 
By the way, do not throw away the previously cut round pipe. It is tightly inserted onto the valve from above, after which a decorative diffuser grille is mounted on it.
What nuances can there be with this method? If your hood is located exactly above the entrance to the ventilation shaft, and the channel pipe goes directly, without any turns in the horizontal plane, then the valve installed on such a straight section does not work normally, at least at 1st speed. 
You simply have nowhere to take the increased pressure to close it. The air will pass this "turn" in a straight line. A corner is a must.
Valve cover and its swivel mechanisms easy to clean and do not be afraid that they will be overgrown with grease. For this to happen, you every day for several hours a day, you will have to fry on the stove and simmer huge hogs in your oven, no less. 
If you do not want to see a "hollow" sticking out under the ceiling, then as an option, you can install the tee so that the middle knee rests against the wall, and where the valve is, it would look to the side. In this case, also close the hole with a decorative cover.
Everything will look much prettier. However, due to the additional rotation, the performance of natural ventilation will slightly deteriorate. And the lattice will reduce it by another twenty percent.
In addition, you will no longer be able to clean the channel by hand or with a vacuum cleaner. But many go for it deliberately and even completely hide the entire structure in a wooden or plastic box. 
As they say, beauty requires sacrifice.
Why does the air from the kitchen get to the neighbors - is the hood to blame?
Despite all the advantages, such a system The hood's connection is found by many critics. They believe that in this way you are grossly interfering with the general ventilation system of the whole house.
For example, everything will be fine with you, but have you thought about the neighbors? Allegedly, due to such a connection of the hood to the ventilation, all odors from your kitchen will automatically penetrate into the apartments along the riser above. 
They started to fry pies, and all the neighbors already know about it. However, all critics are mistaken, based on misconceptions about the ventilation device in apartment buildings.
They think that from bottom to top there is one common channel 110 * 150mm with "holes" for each apartment.
In fact, in 5-storey buildings, all channels are individual and you are unlikely to be able to blow out extraneous odors to your neighbors. In houses from 6 floors and above, there is already a ventilation system with air removal through satellites channels, communicating with a common collecting channel through one floor. 
This common channel has a cross-sectional area 6-8 times larger than individual shafts in apartments with dimensions 110 * 150mm.
Schematically such a ventilation system multi-storey building can be imagined like this. 
Yes, in such buildings, if you turn on several hoods AT THE SAME TIME to a maximum, reverse draft may appear. But this is an extremely rare case.
Look - natural draft from apartments at best ranges from 100 to 150 m3 / h. You have a nine-story house. The first seven floors are cut into a common channel with dimensions of 510 * 270mm, or even more. The resulting natural flow in it is about 1000 m3 / h.
And here you, instead of the usual traction of 150, turn on your hood at 300 m3 / h. Do you think she is able to create a reverse thrust in this case and begin to expel air to the neighbors? 
To do this, it is necessary that all 6 floors do the same, moreover, at maximum speed.
Then one apartment will be unlucky and its inhabitants will have to smell all the aromas of the neighbors' cooking. But this option is unlikely. 
Despite all this, sometimes the air from your kitchen actually gets into other apartments in the house. Or vice versa, you perfectly feel that the neighbors are frying for lunch today. Why is this happening and where to look for the cause?
This happens for several reasons. For which, read more in detail under the spoiler.
Why does the smell from your apartment penetrate your neighbors
Illegal installation of the hood
Nevertheless, if your house was originally designed only for a hood with a natural impulse, and you come across harmful neighbors, then any installation of powerful devices with mechanical forced circulation may turn out to be illegal. 
Neighbors can refer to the "Decree of the Moscow Government". There is such a double clause 3.4 "On the approval of standards for the operation of the housing stock."
You can turn it in any direction. Surely there are similar regulations in other regions. There is also article 3.14.13.
So be careful with the installation exhaust hoods over the slabs.
Although the same rules recommend installing check valves on all ventilation grates, in all apartments. That is, as it were, they say that it is not you who are prohibited from installing the hood, but that everyone else needs to take care of themselves, just in case.
But here is the question of how someone will be lucky with their neighbors.
Natural ventilation channels
For effective ventilation, each room in the house must have two ventilation devices: one is for air intake, the other is for removing air from the room.
Every room in a house or apartment equipped with a supply and exhaust natural ventilation device according to one of three options:
- Supply valve in a window or outside wall for air flow. Overflow hole to an adjacent room with an exhaust duct for air removal (opening in a door or inner wall, partition).
- For air supply - overflow hole from an adjacent room with a supply valve, and exhaust duct
- Supply valve for supply, and exhaust duct ventilation to remove air.
Check, in the house or apartment where you live now, whether all rooms have supply and exhaust ventilation devices ?!
In which rooms it is necessary to make exhaust ventilation ducts
Exhaust ducts of natural ventilation must be provided from the following premises of the house:
- Sanitary facilities - bathroom, toilet, laundry room.
- Kitchens.
- Dressing room, pantry - if the doors of the premises open into the living room. If the doors open onto the corridor (hall, kitchen), then you can do one of two things: arrange an exhaust duct from the premises or install an inlet valve in the wall or window.
- The boiler room must have both a ventilation duct and a supply valve.
- From rooms separated from rooms with ventilation duct by more than two doors.
- On the floor above the first, subject to availability entrance doors from the stairs to the floor - ventilation channels are made from the premises indicated above, or (and) from the corridor, hall.
- On the floor above the first, in the absence of entrance doors from the stairs to the floor, a ventilation channel and a supply valve are arranged in each room of the floor.
In other areas of the house that do not have natural ventilation exhaust ducts, be sure to install a supply valve in a window or in a wall and an overflow opening into an adjacent room.
In addition, natural ventilation exhaust ducts are arranged for ventilation:
- Sewer pipe stand.
Building rules (clause 6.5.8 SP 60.13330.2016) require residential buildings for premises in which gas equipment is located ( gas boilers, water heaters, stoves, etc.), provide mechanical forced exhaust ventilation and natural or mechanical ventilation.
Location and dimensions of ventilation ducts
The minimum size of the side of the natural ventilation channel is 10 cm., and the minimum cross-sectional area is 0.016 m 2., which approximately corresponds to the diameter of a standard ventilation duct pipe - 150 mm.
The minimum size duct will provide air extraction in the amount of 30 m 3 / hour with a vertical pipe length of more than 3 m... To increase the productivity of the hood, the channel cross-sectional area or the channel length is increased. Channels less than 2 m... do not provide the required intensity of natural ventilation.
In practice, the length of the ventilation duct on the floor is usually determined by design considerations - the number and height of the upper floors located above, the height of the attic, the length of the pipe above the roof. On a floor, the length of all channels must be the same. This is done so that the traction force in each channel on the floor is approximately the same.
The cross-sectional dimensions of the channels on the floor are often made the same, but for design reasons it is more convenient this way. The performance of the ventilation channel in a particular room on the floor is adjusted by choosing the size of the ventilation grill.
The ventilation ducts from the premises of the house on different floors are placed side by side, combining them into a block of ventilation ducts.
For design reasons, several ventilation ducts from the premises of one floor are tried to be laid side by side, in one place - they create a block of ventilation ducts.
The block of ventilation ducts in stone houses is usually placed inside the carrier inner wall at home or attached to the wall.
The block is laid out from masonry materials for example bricks. In brickwork, it is convenient to make channels with a cross section that is a multiple of the size of the brick, taking into account the thickness of the seams - 140x140 mm... (1/2 x 1/2 bricks, 196 cm 2) or 140x270 mm... (1/2 x 1 brick, 378 cm 2)
Claydite concrete ventilation two-channel block 390x190x188 mm. Flow area of one channel 168 cm 2 
Concrete blocks for laying ventilation ducts in a private house. Block height 33 cm., width 25 cm., wall thickness 4 cm. Cross-section of one channel 12x17 cm. (204 cm 2)
They produce hollow concrete blocks specially designed for laying ventilation ducts.
A block of ventilation ducts made of masonry materials must necessarily be supported on a foundation or on a reinforced concrete floor.
In other cases, for example, in wooden or frame houses, the block of ventilation ducts is assembled from plastic or steel galvanized pipes. The block of pipes is closed with a box.
How to combine multiple channels into one channel
In a private house, the number of channels is small, so there is no need to combine air flows from several channels (rooms or floors) into one, as is often done in apartment buildings. Each natural ventilation duct in a private house should start indoors and end at the rooftop. Any combination of two or more channels degrades ventilation performance.
In some cases, it is nevertheless necessary to combine several channels, combine them into one common channel of natural ventilation.
Read: Ventilation channel performance
Single channel performance exhaust ventilation section 12x17 cm.(204 cm 2) from concrete blocks, depending on the height of the channel and the temperature in the room:
Capacity of natural ventilation ducts with a cross section of 12 x 17 cm.(204 cm 2) depending on the duct height and room temperature (at an outdoor temperature of 12 o C)
To determine the performance for intermediate values of the channel height, plot the dependence along the axes: channel height and performance.
Similar tables can be found for ventilation ducts made of other materials.
However, for ventilation ducts of the same section (204 cm 2), but made of other materials, the performance will differ slightly from that indicated in the table.
For a channel of a different cross-section, the capacity value from the table can be increased or decreased proportionally.
To increase the performance of the ventilation duct of the same height, it is necessary proportionately increase the channel cross-sectional area. For this, for example, a concrete block with a larger opening is chosen, or two or three ducts of the above size are used for ventilation of one room.
Calculation of natural ventilation of a private house
V building regulations the minimum required performance of natural ventilation channels is indicated. Usually, people feel better when more fresh air is supplied to the room than the norm. The performance of the natural ventilation channel is highly dependent on atmospheric and other changeable factors (air temperature inside and outside, wind pressure and direction, resistance to air flow into the room). All this suggests that for a private house, it makes no sense to scrupulously accurately perform the calculation... I recommend rounding off the calculation results towards higher performance of natural ventilation ducts. During operation, if required, the channel capacity can be easily reduced.
Calculation of natural ventilation is carried out in order to determine the size of the ventilation ducts based on the volume of exhaust air.
When determining the volume of air removed through the channels of natural ventilation, it is taken into account that air enters the rooms with supply valves from the street, then this air flows into the rooms with exhaust channels, and is removed through the channels again to the street.
Calculation is carried out for each floor houses in the following sequence:
- Guided by the standards (see), determine the amount of the minimum volume of air that must come from the street for ventilation all rooms with supply valves - Q p, m 3 / hour.
- The standards determine the amount of the minimum air volume that must go outside for ventilation all rooms equipped with an exhaust ventilation duct - Q in, m 3 / hour.
- Compare the calculated minimum values of air flow from the street (Q p, m 3 / hour) and going out into the street (Q in, m 3 / hour)... Usually one of the quantities turns out to be larger than the other. The larger of the two values is taken as minimum design capacity of all exhaust ventilation ducts on the floor- Q p, m 3 / hour.
- Based on the vertical dimensions of the house, the height of the natural ventilation channel on the floor is assigned.
- Knowing the height of the ventilation channel, and the total estimated minimum performance of all channels on the floor (Q p, m 3 / hour), according to the table (see above), the total number of standard channels from concrete blocks is selected. The total productivity of the selected number of standard channels must be at least Q p, m 3 / hour.
- The selected number of standard ducts is distributed between the premises of the house, which must be equipped with exhaust ventilation ducts. When distributing, take into account the need to ensure standard air exchange in each separate room with a ventilation duct.
An example of calculating the natural ventilation of a private house
For example, let's calculate the natural ventilation in one-story house with a total floor area of 120 m 2... The house has five living rooms total area 90 m 2, kitchen, bathroom and toilet, as well as a dressing room (pantry) with an area of 4.5 m 2... Room height - 3 m... The house is made with natural ventilation of the underground space through a ventilation duct. Height of the ventilated space under the floor 0.3 m... For the installation of ventilation ducts, we use concrete blocks - see above.
Fan at the entrance to the natural ventilation duct
Continuation: to the next
