Unfortunately, the ventilation system sometimes does not work correctly. This is when it begins to blow from the ventilation back into the living quarters of the house. Brings air from the ventilation shaft with it unpleasant odors and you feel it right away. You should not postpone the solution of this problem indefinitely, because it will not be solved by itself. Let's see why ventilation works in the opposite direction.
Natural ventilation at home
What is this ventilation system? In fact, this is a complex of air ducts in a private house or a system of shafts in apartment building, in which there is one main riser, stretched from the basement to the roof. It is he who creates traction due to the temperature difference between indoors and outdoors. And the greater this difference, the stronger the hood works. Let's add the wind perpendicular pressure according to the type of cross sections. This is when the wind blows in a horizontal direction relative to the riser, and behind it it pulls air from the ventilation. That is, the suction of air from the premises occurs naturally rather than using additional equipment such as a fan.
Of course, in such a system there must be an influx of air so that a vacuum does not form inside the house or the draft does not decrease. Therefore, vents are left in the foundation or holes are made in the floor of the first floor.
Causes of violation of air circulation
If the ventilation system is not working correctly, then there is a reason for that. There are many, but the main two are:
- There is no supply ventilation.
- The indoor temperature is lower than outside. This usually happens in the summer when it's hot.
But the main reason is still the lack of supply air flows. Usually in apartments, outlets to the ventilation shaft are made through the bathroom, toilet and kitchen. And the flow of air occurred through the windows (their leaks) and the front door. Today, when plastic windows with full sealing of joints and connections are installed instead of wooden windows, the problem of inflow has become serious. Most often, reverse thrust appears because of this. This problem is solved by installing window systems supply valves.
Other causes of traction disturbance and reverse flow include:
- malfunctions of the system itself;
- installation of fans instead of gratings;
- installation of a flow hood, which is connected to the ventilation duct;
- the absence of an umbrella on the roof or the destruction of the mouth of the channel.
Causes of ventilation failure
A large number of factors can be attributed to the causes of the malfunction. The main thing to understand is that when it blows from the ventilation system in the apartment, this is not the same thing if the same effect appeared in a private house. That is, malfunctions in two buildings can be different, because the violation of draft in them has different causes.
For example, in an apartment, most often this happens due to the installation of a fan or hood in the kitchen, which begins to press through its channel, and the air inside, moving to the riser with pressure, does not have time to go up with the whole mass. That is, it partially enters the adjacent channel of the toilet or bathroom. It is in these rooms that the opposite effect is formed. The same thing happens in reverse direction if the kitchen fan is turned off and the bathroom fan is on. This also happens with neighboring apartments located one above the other.
This suggests that it is impossible to mindlessly install additional exhaust devices without calculating their power. And the more powerful the fan, the stronger the reverse draft of the ventilation system in the apartment high-rise building.
For this reason, this cannot happen in a private house, because at the design stage today they are trying to distribute ventilation ducts to all rooms separately. That is, the kitchen has its own riser, the toilet and bathroom have their own. But sometimes there is another problem in the house. Most often, risers are combined into one or two common channels inside the attic, and then one or two pipes are led out through the roofing. And here horizontal sections appear in the ventilation system. The main task of the designer is to use as little of this type of duct as possible, and to minimize the angle of inclination of the horizontal sections (the decrease should be minimal). That is, the steeper this section, the better the upward movement of air.
And three more reasons:
- Lack of thermal insulation. Cold air in winter enters the air ducts, where it freezes, turning into ice. This usually occurs at the mouth of the canal. The consequences are a reduction in cross section.
- The absence of an umbrella (visor), which can lead to rain and reduce traction. This disrupts air circulation.
- The ventilation in the house is littered.
So, in order to remove reverse thrust, you must first understand why it appears.
Causes of reverse thrust
As mentioned above, reverse draft in ventilation appears for two main reasons:
- Full tightness of the premises.
- Installation of additional exhaust devices in the ventilation ducts.
All other reasons are secondary, some of which do not create reverse thrust, but simply the ventilation stops working. With ventilation in an apartment it is more difficult, because the system itself is a complex set of channels, often made of concrete. Branches depart from the riser for all apartments, through which the air from the premises must be removed to the street. And if a neighbor on the lower floor installs a powerful kitchen hood, then reverse flow air masses will be felt not only by him, but also by neighbors from the floors closest to him.
In a private house, back draft occurs for other reasons, because the ventilation in the apartment is different from ventilation system private house. This is where installing fans can solve the problem. But you just need to determine the installation location for different risers.
Self-determination of traction
- There are two ways:
- The simplest is to put your palm on the vent, and if the ventilation is good, you should feel the movement of the air flow.
- Attach a napkin or paper sheet to the grill. If the first holds on to the second, then the traction is good, there is no reverse effect.
Ventilation problems in multi-apartment buildings
Ventilation problems usually occur after years of home use.
- Its cross section becomes smaller due to the debris that has fallen inside, rodents and birds.
- Destruction of the walls of ventilation ducts due to condensate.
- The absence of a head is atmospheric precipitation that has got inside.
All this reduces traction, which means that humidity rises inside the apartments, and unpleasant odors will become the eternal companions of the rooms. What to do?
Solving the problem with a fan
Probably, many thought that the conversation was about installing fans in place of the ventilation grilles. No one forbids doing this, although it has already been described above what this can lead to.
We are talking about a fan that is installed in the system on the roof. It can be a mechanical deflector or a rotary turbine. Both devices are powered by a breath of wind, so in calm weather they are of no use. Although, as practice shows, it is the installation of these devices that dramatically increases traction and prevents reverse flow.
As for the fans on the ventilation grilles, it is worth first of all to calculate their power. It depends on the cross section of the ventilation ducts and on such an indicator as air exchange in the premises. For example, in the kitchen, this indicator should vary in the range of 12-20 m³ / h, depending on the type of stove and the number of burners.
To do this, you need to calculate the volume of the kitchen. For example, the area of the room is 3x4 m with a ceiling height of 3 m, the volume will be 36 m³. Now we multiply the resulting value by a factor of 12-20. At minimum value fan capacity is 432, with a maximum of 720 m³/h.
Preventive measures
What needs to be done to prevent backlash.
- Maintain the ventilation system in good condition.
- Do not install fans and extractors in ventilation ducts. Use a recirculation hood or take its outflow outside the room to the street: through a wall or window glass.
- Install baffles or rotary turbines at the end of the riser.
- Organize the flow of air into the premises by any means.
- Install interior doors that block the movement of air between rooms. Strong drafts are also causes of backflow.
- In winter, clean the ventilation system from snow and ice.
- Produce periodical
Ventilation of residential buildings is one of the key points in providing comfortable air environment for people. Poor air circulation in the home can not only adversely affect the health of the occupants, but also require spending on additional exhaust systems. Operating air ducts are also one of the main points for ensuring fire safety. In this material, we will explain how ventilation is arranged in an apartment building and what measures can increase its efficiency.
Purpose of general house ventilation
The air in a residential apartment is always subject to pollution. Cooking smoke, bathroom fumes, bad odors and dust all end up in the air and create unfavourable conditions for people's lives. Stale air can even lead to the development of diseases - asthma and allergies. That is why every apartment building must be equipped with a common ventilation system.
Functions of ventilation in a residential area:
- ensure the penetration of clean air into the apartments;
- together with the exhaust air, remove dust and other impurities harmful to health;
- regulate humidity in residential and utility rooms.
Most of the urban population of our country lives in prefabricated houses built back in the Soviet era, while others move to new buildings. Ensuring ventilation of residential buildings is mandatory requirement when building houses. However, the level of ventilation in multi-apartment residential buildings remains quite low. It is customary to save on air duct systems during construction.
On the this moment You can find the following types of ventilation in residential buildings:
- with natural inflow and exhaust;
- with forced air movement through ventilation installations.
AT modern houses elite-class heating and ventilation systems comply with the latest standards and are created using special equipment and materials. For ventilation of multi-storey residential buildings of panel type, natural air exchange is used. The same applies to brick residential buildings of the Soviet era, as well as modern buildings budget class. Air must enter through the holes between the doors and the floor, as well as special valves on the plastic windows.
Ventilation in a panel house works as follows. Air is discharged upwards through vertical ventilation shafts, thanks to natural draft. It is pulled outside the house through a pipe located on the roof or attic. When air enters the apartment through open windows or doors, it rushes to those located in the kitchen and bathroom - where cleansing from smoke and moisture is most needed. Thus, stagnant air is discharged into the pipe, and clean air enters the room through the windows.
If you stop the flow of fresh air, ventilation will not work efficiently. Residents of apartments in apartment buildings often forget about the natural ventilation of the premises when they install additional exhaust systems. Here is the list common mistakes during repairs that stop air circulation:
- installation of deaf double-glazed windows made of metal-plastic;
- elimination of the gap between the door leaf and floors when replacing interior doors;
- installation of axial fans in the toilet (affects the ventilation of neighboring apartments).
When finishing living rooms it is worth remembering to create natural ways for ventilation. Can install plastic windows with special valves that will automatically supply air from the street.
Interior doors should be selected in size so that they do not stand close to the floor. When installing additional fans, you can also configure them for supply.
Ventilation schemes for residential buildings
Depending on the construction plans, ventilation can be completely different design. In this section, we will try to figure out how ventilation is arranged in a panel house on the diagrams and talk about the degree of effectiveness of one or another type of its implementation.
The most successful ventilation scheme in a panel house is individual, when each apartment has a separate channel with access to the roof.
In this case, the ventilation shafts are not interconnected, it improves, and polluted air from neighboring apartments does not enter the house. Another variation of such a ventilation scheme in Khrushchev is that from each apartment, separate channels lead to the roof, where they are connected into a single pipe that brings air masses to the street. 
Unfortunately, quite often the simplest, but inefficient method of ventilation is used, in which air from all apartments enters a single large shaft - just like ventilation is arranged in Khrushchev. This allows you to save space and costs during the construction of the building, but it has a lot of unpleasant consequences:
- dust intake and unpleasant odors from other apartments - residents of the upper floors are especially susceptible to this, where the air rises naturally;
- rapid contamination of the common ventilation pipe;
- lack of sound insulation.
There are several other ways to remove air through ventilation shafts - with horizontal channels in the attic and the outlet of the pipe to the attic without a chimney. In the first case horizontal ducts reduce air draft, and in the second - the attic is polluted due to the lack of output to the street. The ventilation scheme in Khrushchev and other Soviet-style buildings, although budgetary, is inconvenient for residents.
Schematic diagrams of some natural ventilation systems of residential buildings: (a) - without prefabricated ducts; (b) - with vertical collection channels; (c) - with horizontal collection channels in the attic; (d) - with warm attic
Fortunately, there is modern system ventilation, which automatically draws and supplies air. Its design includes a fan that pumps air into the mine. It is usually located in ground floor building. On the roof of the house there is an exhaust ventilation of the same power, which with force removes polluted air masses from the air duct. This is the simplest ventilation scheme in an apartment building. It can also be arranged with the use of energy-saving equipment - recuperators. The task of the heat exchanger is to take heat (or cold) from the exhaust air and transfer it to the supply air.
Ventilation shafts, as a rule, come from the basement of a multi-storey building, additionally providing its protection from dampness and fumes. The ventilation of the basement is provided by natural draft, and in modern houses they also install air handling units. To remove raw air from the basement, common ventilation shafts are used, which exit through openings on each floor and in each apartment.
Airing the basement, the place where the natural ventilation system begins, is one of the main conditions for its proper operation. To do this, holes are made in the basement walls through which fresh air enters the basement. It not only reduces humidity at the base of the house, but also creates traction in the common house mine.
The shape of the holes can be simple - round or square. They must be located at a sufficient distance above the ground so that water and dirt from the street do not get inside. The optimal distance from the ground is not less than 20 cm. The holes should be placed evenly around the perimeter of the basement, if there are several rooms in it, it is necessary to organize several air ducts in each. The vents must not be closed, otherwise the whole principle of ventilation will be violated apartment building. From penetration into the basement of animals, the holes are covered with a metal mesh.
Calculation of apartment ventilation
Natural or artificial ventilation of a residential building is calculated by specialists during the construction of the building, and the residents of the building receive apartments with a ventilation system “by default”. It will not work to change the scheme of the ventilation system in Khrushchev, this will require serious intervention in the structure of the building. However, with the help various devices you can improve the air circulation in your apartment. For this it is necessary.
If you are not satisfied with the ventilation in the apartment, you can install additional hoods in the kitchen and fans on the grates in the bathroom. In this case, you should remember the basic rule - the amount of air drawn out should not exceed the amount entering the apartment. In this case, the ventilation systems will work as efficiently as possible. Some models of hoods and fans can work on the flow of air - they should be installed if the room is not sufficiently ventilated through windows and doors.
Special attention worth the power exhaust devices, for small apartments a capacity of 50 to 100 m³ of air per hour will suffice. To determine exactly what load for the device will be optimal, you can measure the amount of air masses in the room. To do this, the area of \u200b\u200bthe apartment is summed up and multiplied by three. The resulting volumes of air must completely pass through the fans within an hour.
You can organize additional air flow with the help of air conditioners, hoods and fans. In combination, these devices will perform the main tasks of ventilation of premises:
- the hood in the kitchen will clean the room from unpleasant odors, grease and smoke, filling it with clean air;
- fan in the bathroom - to remove moist air;
- air conditioning - cool and dehumidify the air in the room.
These devices will ensure good circulation of air masses in different rooms and regulate their cleanliness - in the bathroom and kitchen they are simply irreplaceable.
The amount of supply air can exceed the volume of exhaust air by 15-20%, but not vice versa.
home ventilation maintenance
Often, due to clogging of the air duct or outlet grate, ventilation does not work. you can independently within your apartment by removing the grate and cleaning the pipe walls with a brush, broom or vacuum cleaner. Particular attention must be paid to the mesh that closes the entrance to the mine - it works like a filter on which all impurities remain.
Complete is carried out by a special service at the request of residents.
First, a diagnosis of the performance of the exhaust channels is carried out and a work plan is drawn up. To check the cleanliness of the mines, a video camera on a cable is often used - it allows you to determine the places where dirt accumulates and the places where the pipe is deformed. 
After that, the cleaning of the duct begins. Professionals use weights, pneumatic brushes, weighted brushes and other tools. Ordinary residents should not engage in such work - this can harm the integrity of the pipe.
Natural ventilation in a high-rise building is not very efficient compared to mechanical ventilation, but it requires less cleaning. A team of specialists should be called every few years when obvious signs air duct pollution. Automatic ventilation systems are under heavy load and require more thorough cleaning. These systems are often maintained by the companies that install them.
Monitoring the performance and increasing the efficiency of home ventilation is one of the key points in creating a healthy microclimate in your home. By taking a number of measures to improve the ventilation of your home, you will save yourself from dust, unpleasant odors, kitchen or bathroom products in the air.
WHAT IS VENTILATION AND WHAT IS IT FOR?
HOW TO CHECK WORKABILITY?
HOW TO NOT STAY WITHOUT AIR?
A LITTLE THING ABOUT THINGS...
THE "FAMOUS" PROBLEM OF THE LAST FLOOR
THE MOST COMMON MISTAKE
WHY "SUDDENLY" THE VENTILATION STOP WORKING?
WHAT IS VENTILATION AND WHAT IS IT FOR?
According to existing standards, each dwelling (apartment) must be equipped with ventilation, which serves to remove polluted air from the non-residential premises of the apartment (kitchen, bathroom, toilet). Ventilation is the movement of air, air exchange. Each person breathes throughout the day, uses cooker, washes or washes, 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 this results in a big problem for those living in such an apartment - the windows on the windows begin to fog up and condensate flows onto the windowsill and wall; the corners are damp, and mold appears on the walls and ceiling; linen dries in the bathroom for 2-3 days, and when using the toilet, the smell spreads throughout the apartment. Plus, if in an apartment without ventilation there is a chest or completely Small child, 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 ventilation works 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 a 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 sheet does not rest on the grate and falls, the ventilation does not work. If the leaf is not attracted, but rather deviates from ventilation grille- it means that you have a reverse draft and you breathe foreign odors, which means that the ventilation does not work.
HOW TO CHECK WORKABILITY?
Ventilation can be checked or measured. It is measured with a special device - an anemometer. This device shows how fast the air moves in the ventilation duct. Having a calculation table in hand, you can substitute the values of the anemometer and the cross section of your ventilation grill into it and you will get a figure that will tell you how many cubic meters of air per 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 measurement data will be incorrect.
According to the "Methodology for testing the air exchange of residential buildings", measurements are carried out at a temperature difference between indoor and outdoor air = 13ºС (example: +5ºС outside; +18ºС in the apartment), and at the same time, the air temperature outside should not be higher than + 5ºС.
The fact is that during the warm season, ventilation works worse and nothing can be done about it, because these are the laws of physics on this planet. If ventilation is measured at a temperature warmer than +5ºС, then the obtained measurement data will be incorrect. And the warmer the outside temperature is, the further the measurement data will be from the normative ones. In extreme heat, in some cases, even absolutely perfect ventilation may stop working or even work in the opposite direction (reverse draft).
To understand why this happens, we must remember what each of us heard at school in physics lessons. The lower the temperature, the greater the air density, i.e., the air is heavier. 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 +18ºС, and on the street -3ºС, then warmer (lighter) internal air through the ventilation duct will tend from the apartment to the street. As the temperature rises outside, specific gravity outside and inside air will begin to equalize, which means that the draft in the channel will begin to weaken. And, if the temperature in the apartment is, for example, + 24ºС, and the temperature outside is + 30ºС, 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 to “flow out” of the apartment.
That's why in hot weather there is a high probability that ventilation can give a reverse draft, although in this case it cannot be considered faulty, because under these conditions, according to the laws of Nature, it could not work.
So, you can measure ventilation only if it works. But first you need to find out if it works.
As already mentioned, anyone can do this - it does not require much effort. To do this, you need a small piece of toilet paper. No need to take a sheet of newspaper, magazine or cardboard. Why?? According to existing standards, the kitchen (with an electric stove), bathroom and toilet are supposed to be: 60, 25 and 25 m³ / h, respectively. To achieve these values, a relatively low air velocity through the ventilation grille is required, and such movement can only be detected thin sheet paper (better if it is toilet paper). In some apartments, sometimes a piece of thick, heavy paper also attracts, but this suggests that the ventilation in this apartment works so well that it exceeds the required rate. There is one more thing to consider here. necessary condition traction checks. According to the same “Methodology for testing the air exchange of residential buildings”, when checking ventilation, in one of the rooms the window sash is slightly opened by 5–8 cm and the doors between this room and the kitchen or bathroom are opened.
We had the opportunity to attend many commissions that met to assess the state of ventilation in various apartments and, sometimes, it was necessary to observe how a representative of the inspecting organization checked the ventilation at closed window. This is mistake!! In our country, ventilation in residential premises is forced-air and exhaust 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 cracks in windows, doors and other structures. In the early 90s, hitherto unknown plastic windows with sealed double-glazed windows and metal doors with seals appeared in our country. Undoubtedly, these products are not like our old wooden windows with their eternal drafts, but one problem has arisen here - new technologies have come, but the norms have 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 eliminate these leaks . So it turns out that hermetic 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 TO NOT STAY WITHOUT AIR?
Let's describe 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 bathroom, and the other for the kitchen and a “hood” above the stove is connected to the kitchen ventilation duct (one can say a classic situation). Now "hoods" (i.e. exhaust 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 for 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”, pass cubic meters of air from this apartment through itself. As a result, the “hood” begins to pump air out of the apartment and creates a vacuum, and since the windows and the door are very tight and there is no air to circulate through them, then there is only one place through which air can flow into the apartment - the vent from / node (!!!). In such a situation, even normally working ventilation from the / node (toilet and bathroom) will start to work in the opposite direction (reverse draft). And, since the ventilation within the attic is integrated into a common system, extraneous odors from other floors begin to enter the apartment, sometimes obscenely fetid.
AT this case the solution to the problem with reverse draft is quite simple - 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, you will have to come to terms with the fact that air will flow into your apartment through an open window - otherwise there is no way. Supply devices are able to compensate for the air removed through the standard ventilation channels, but providing a powerful exhaust with air is a difficult task for them.
A LITTLE THING ABOUT THINGS...
Not a very common problem. However, if you don’t know about it, then you can look for the cause of reverse thrust for a very long time and find nothing. So, there is a reverse draft in the ventilation duct, but during the examination it turns out that the duct is absolutely clean, in the attic the horizontal junction boxes (if any) are in perfect order, and the shaft that goes 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 operation of ventilation, the ventilation duct of the apartment must begin with a “plug”, i.e., the air entering the duct through the ventilation grill must have only one way - up. In no case should there be a downward movement - either immediately at the bottom of the ventilation grill, or with a small recess, but the channel must be muffled (blocked) in its lower part. Otherwise, there is a high probability that such a channel will give reverse 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-entrance "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. Typically, apartments are connected to such a ventilation system "in a run" - for example, the 1st floor to the satellite channel to the left of the shaft, the 2nd floor to the right, the 3rd floor to the left, etc. The ventilation blocks are cast at the concrete goods plant in such a way that the satellite channels (they are also upper stages) communicate with the common mine through windows every 2.5 meters. That is, the air must get from the apartment into the ventilation grill, rise along the satellite channel up to 2.5 meters, rest against the “plug” and exit through the window into the common shaft (collective channel). But that's the whole trouble, that in these houses there are NO "stubs".
Most likely, the designer provided for the so-called "universal" ventilation unit. The fact is that if ventilation blocks are cast at the factory with a division into “right” and “left” or “for even floors” and “for odd”, then confusion is inevitable during their installation and problems are guaranteed. Therefore, the ventilation unit 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 into the satellite channels on the spot.
The designer's faith in the integrity of our builders, subject to 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 homes. 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 by extraneous odors in the apartment. The air flow, rising through the channel and flying past the ventilation grill, will either give a reverse draft, or will greatly impede the removal of air from the apartment. And, if you install a plug, it will cut off the lower air flow and direct it to the collection channel through the provided window. Thus, the ventilation in the apartment begins, as it were, from scratch - without experiencing any obstacles and not burdened by the struggle with other air flows, that is, as it should be.
THE "FAMOUS" PROBLEM OF THE LAST FLOOR
Sometimes, when people turned to us for help and when describing their problem, they said that they had the last floor in the house, then this was enough to establish the reason for the lack of normal ventilation without leaving the place. Then all that remained was to go out and confirm their assumptions. Believe me, a huge number of people, thousands, suffer from this problem. The fact is that for the normal operation of ventilation in an apartment, it is desirable for air to pass through the ventilation duct at least about 2 meters vertically. On any other floor, this is possible, but on the last one such a possibility is excluded - the attic space acts as an obstacle. There are three ways to bring ventilation from an 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 this way until the beginning of the 20th century, and then they began to gradually move away from this method. The reason is the increase in the number of storeys of houses. This method does not interest us, because problems almost never arose with it. The second way - ventilation, reaching the attic, was covered with horizontal sealed boxes, which were connected to a shaft that went out over the roof. The third way (modern) - ventilation first enters the attic, which serves as a kind of intermediate ventilation chamber, and after that it goes outside through one common ventilation shaft.
We are interested in the second and third options. In the second case, the following happens - the air through the channels from all floors rises up to the level of the attic and breaks into a horizontal junction box mounted in the attic. In this case, the air flow hits the cover of the horizontal ventilation duct. The air flow deviates slightly towards the ventilation shaft, but if the internal section of the horizontal attic box is insufficient, then an area appears in the box high blood pressure and the air tends to find its way out into any nearest opening. There are usually two such exits (holes) - a ventilation shaft designed for this and an upper floor channel, since it is the closest and is located almost in the box at a distance of only 40-60 cm. And it is easier than ever to "push" it into reverse side. If the section of the box in the attic is sufficient, but the cover is mounted too low, then the same thing happens - reverse draft - the air flow, due to the small height of the cover, does not have time to deviate towards the ventilation shaft and an impact occurs. The reflected air flow “presses through” the ventilation of the upper floor and all the smells from the lower floors come into this apartment. There are two ways to deal with this - global and local. Global - to increase the section of the attic horizontal junction box by changing its height by 2 - 3 times, plus the device inside the box of "cunning" devices, which we call "cuts". But, firstly, this should be done by specialists, and secondly, it is not recommended to increase the section of the duct, if to the ventilation shaft with opposite side the same boxes are attached. 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 over the duct. These individual channels are insulated so as not to disturb the temperature and humidity regime (TVR) of the attic. And that's it - the ventilation in the apartment works.
Now, as for the third (modern) option for removing air. According to this principle, ventilation works in all high-rise buildings (series: P - 44, P3M, KOPE, etc.). The last floors in such houses suffer more often not from reverse thrust, but from weakened one. Instead of passing the 2 meters vertically laid down by the norms and then connecting with the general flow, on upper floors the following happens - the air, entering the channel, passes only about 30 centimeters vertically and, without having time to gain strength and speed, dissipates. Ventilation thus does not disappear, but air exchange in top apartment greatly reduced. If the entrance and intersection doors of the attic are open (it often happens), 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. Bring the pipes to a height of approximately 1 meter and tilt them slightly towards the common shaft, so that the air flow rising from below, flying next to the removed pipes, picks up and draws air from the channels of the upper floor with the force of its flow.
THE MOST COMMON MISTAKE
Each of us has a kitchen in the apartment. Everyone has a stove (gas or electric) in the kitchen. And the vast majority have an exhaust “umbrella” above the stove (in the common people - “hood”). What is the delusion? That so many people consider a "hood" to be the equivalent of kitchen ventilation. Otherwise, how to explain the fact that, when installing the hood over the stove, the air duct from it is led into the kitchen vent, completely closing it?
They do this for several reasons - either they were advised by the builders who made the repairs, or from the full confidence that even so the air is perfectly removed from the kitchen. Plus, sellers of hoods claim that the power of the purchased hood should be selected taking into account the area of \u200b\u200bthe kitchen. Actually, this is all a 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 find the word ... HOOD!
Note: 1) we are talking about regulatory documents, not reference; 2) hood - a kitchen hood (noun), and not a hood - as an action (verb).
So, if there is no such thing as an exhaust hood in the regulatory framework, 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 words do not? And everything is very simple, there is a word and hoods, 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 a natural impulse.
Those. air enters our apartments through leaks in windows, doors and building structures, as well as through special supply valves or channels, but leaves through the ventilation channels located in the kitchen, bathroom, toilet.
How is this related? Let's try to explain. Any building construction or communications are calculated for certain loads. Ventilation is no exception to this list. Our channels have rather limited bandwidth capabilities. AT best conditions their performance is 150 - 180 m3 / h (for comparison: modern hoods have a capacity of 600-1100 m3 / h)
Sorry if we took a lot of your time. Here we come to the confusion. The fact is that there are still norms for mechanical ventilation, which differ significantly from the norms for natural ventilation. For example, air exchange for a kitchen with natural ventilation should be 3-fold, and with mechanical ventilation - 10-12-fold. So, the sellers of hoods apply the norm (10-12 times), without thinking that the hood above the stove and the norms of mechanical ventilation are in no way connected with each other and the hood above the stove has NO RELATIONSHIP TO THE VENTILATION of the premises.
The exhaust hood is not designed to ventilate the kitchen. It is only to remove polluted air that is in 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. For the hood, “reaching out” to this air is an almost impossible task. The fact is that the behavior of the air flow during suction and ejection is different. During suction, air is taken from a distance of not more than one diameter of the suction hole, and an air jet is ejected at a distance of fifteen hole diameters. 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 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. This creates air movement in the room, and additional air flows are involved in the mixing process. How much is pumped out of the room, the same amount is supplied 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 void, which Nature does not like, will be filled with air that came from anywhere - from the window, from other rooms, from cracks. But cooking odors that have risen to the ceiling are hardly involved in mixing and are difficult to remove. It is not for nothing that the instructions for the hoods say that ... "... for the purpose maximum efficiency operation, the exhaust hood should be located 60 cm from the electric stove and 75 cm from gas stove... ". "... During operation of the hood, avoid air currents - this can cause odors to spread throughout the room." If the hood were designed to ventilate the kitchen, then there would be no such recommendations in the instructions, and the exhaust “umbrella” 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 come up with the sellers of this product. The area of the room does NOT affect performance. And vice versa, the power of the purchased hood does not follow from 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 vast 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 meager effect. More air than such a channel can still not let through, no matter how hard you try. In almost every manual for a fan or hood, there is a diagram showing the 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 result, a drop in productivity are: irregularities inside the channel; displacement of floor blocks; protruding solution; narrowed section; material and shape of connecting air ducts; every turn in the airflow path.
As a result, due to the influence of these factors, increased pressure will be created in the channel and at the approach to it, and, as you know, the higher the pressure, the lower the exhaust performance. This means that a POWERFUL hood “suffocates” itself. And the more powerful the hood, the more it "locks" itself.
You can connect an exhaust hood with a capacity of 1000 m3 / h, you can 1500 m3 / h, you can 5000 m3 / h (if any), but in all cases the result will be the same - you can push a little more air into the channel and that's it !!! The rest is loss!
Once, on one of the connections of the hood to the 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, they asked the client for permission to experiment a little. The air duct was disconnected and a pre-prepared insert with an anemometer was installed. Extractor hood four-speed "SATA". The fan is centrifugal. The length of the duct is 3.5 meters with two turns. The air duct is plastic, with a diameter of 125 mm. The maximum productivity of the exhaust dome is 1020 m3/h. The anemometer was installed before the last turn (at the very entrance to the ventilation unit). The first speed - the anemometer showed 250 cubic meters / hour. The second speed - indications of 340 cubes/hour. The third speed - indications of 400 cubes/hour. Fourth speed - 400 cubic meters / hour. Bottom line: 1) the difference in performance between the first and fourth speeds is minimal; 2) the channel missed EVERYTHING THAT COULD, which means that the losses are simply huge; 3) the noise at the third and fourth speeds has grown, but there is no 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 should not hope that it will provide you with full air exchange. We do not discourage the purchase of a hood in general and do not claim that this is not a necessary and useless thing. Of course it is not. The only goal that we pursue is the desire to warn the consumer against general delusion. Namely: 1) you should not take the exhaust hood in the kitchen as an equivalent of room ventilation - it has nothing to do with this; 2) when buying a hood, you can’t build on the size of the room - these are unrelated things.
WHY "SUDDENLY" THE VENTILATION STOP WORKING?
It happens. It seemed to work, worked for many years and "suddenly" stopped. Many residents tend to believe that the reason for this is the neighbors who climbed into the ventilation riser and blocked something there. Of course, there are such “craftsmen”. These "specialists" are well aware that current flows through the electrical network, poop flows through sewers, water flows through pipes, but when it comes to ventilation, logic fails them - they cannot understand that there is not a void at all that needs to be filled, there is air moving.
But it's not about them. If we immediately cut off all the cases when the neighbors really violated the ventilation and try to figure out the rest of the reasons that affected its performance, it turns out that the residents themselves create a huge number of problems with ventilation.
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. Houses of the following series are suitable for this scheme: P-44, P-3M, KOPE, P-46, P-55, P-30, P-42, P-43, some monolithic houses and many less common series.
The ventilation in these houses consists of a prefabricated channel (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, not reaching the same individual channel of the apartment above, exits through an opening into a common shaft, where the air continues to their movement to the attic and further into the street.
To make it easier to understand this scheme, imagine a full-flowing river with small streams flowing into it. This is the considered ventilation scheme. The river is a prefabricated mine; streams flowing into it are satellite channels.
As tributaries feed a full-flowing river, so satellite channels fill the prefabricated mine with air. If you start blocking 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 collection shaft will decrease significantly. Since the ventilation system of a house is a chain of interrelated and interdependent links, a 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, entrance, and sometimes the house.
You can trace all the stages of violation of the ventilation system.
Ordinary 17-storey panel house, which are full all the time. The ventilation scheme used in these houses is perhaps the best that a person has come up with for residential high-rise buildings. This ventilation system is able to work even in extreme heat. Although, by definition, it should not work in the summer. In hot weather, according to all conditions and rules, ventilation must stop or tip over (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 the difference in pressure difference between the lower and upper points, a rather strong air flow (thrust) arises. The "warm attic" is the reinforcing factor here. And this bundle is not able to "interrupt" even strong heat. BUT ... only if the conditions necessary for it to work are created for this ventilation system.
One entrance of any multi-entrance building with a warm attic is a closed and isolated system. The ventilation of any apartment of this entrance is component this system. That is, the ventilation of each apartment depends on the other apartments of 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. What if there are several? If there are five, or ten, or twenty, or half. What 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 its strength, weakens. There is a certain critical point after which it fails. That is, the sum of all air flows entering the attic is not enough to push this air out of the attic into the atmosphere. Because the common exhaust shaft going from the attic to the roof (to the street) is quite impressive in size. And this abyss "wants to eat", i.e. its dimensions are designed for the passage of a certain volume of air, which it does not receive. There is a saying: “You can’t 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 mine is reduced and the thrust overturns. In winter, the “heavier” cold air sinks, and the outgoing warm air stream (“awl”) is too small for the large size of the mine (“sea”).
A reasonable question arises: “Why does the volume of air emitted through the ventilation shaft into the atmosphere decrease? What is the reason?".
The answer can be obtained on the example of the smallest link in the overall ventilation system - on the example of 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 channels 24 hours a day remove air from the apartment to the ventilation. The remote dirty, humid, exhaust air must be replaced by another air - outside, fresh, enriched with oxygen. i.e. INFLOW. Thanks to this circulation, this constant replacement (inflow), normal living conditions are maintained in the apartment.
Only the influx of outside air can be considered normal, full-fledged inflow. The air that comes from landing through the cracks in front door or, who came from the next room (apartment), in terms of quality, nothing better than that air that is already in the apartment. It is just as dirty, damp, it has already been smoked, puffed with toilet freshener and saturated with the “aromas” of the kitchen. It's like in the old joke about the concentration camp: “Today there will be a change of linen. The first barrack changes with the second.”
Previously, the flow into the apartment was mainly carried out through cracks and leaks in our old, terrible, crooked, leaky windows. When replacing these shameful windows with new sealed double-glazed windows, the previous order of air circulation is violated. New windows are very tight, there are practically no gaps in them, which means that the inflow of outside air through them is almost zero. Temporary opening of vents and sashes is self-deception. Ventilation works constantly, which means that the need for inflow is also constant.
Has anyone tried to suck the air out of plastic bottle?? Correctly. It's impossible. What if you make a hole in the bottle? Then you can pump air out of the bottle indefinitely. The hole is the inflow. A 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 (a stronger channel) will start pulling the other channel. That is, the second, weaker channel will begin to function as an inflow, which was ruined by the installation of new windows;
b) both ventilation ducts will work as before, and the missing inflow will be compensated through the gaps between other apartments. That is, they will suck into 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 the 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 air inside the house, 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 disturbed.
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 excluded from the general ventilation system of the entrance. This is ballast. Without an inflow, these apartments hang like weights on the legs of the ventilation system. And if in summer or winter (less often in winter) a reverse draft “suddenly” comes out of your ventilation ducts, then you can safely say “thank you very much” to these neighbors. They tried very hard.
Main conclusion.
You can not thoughtlessly install sealed double-glazed windows. These windows are not on their own. They are part of the ventilation system. It is up to you whether the ventilation will work or not. Decided to install sealed double-glazed windows?? Organize a CONSTANT INFLOW!!!.
Air exchange is provided by draft in the system of exhaust air ducts. They start in the rooms (as a rule, in the kitchen and in the bathroom, in the most "dirty" rooms in the house). Further, the air ducts go up to the attic and from there - to the roof.
Air draft is created 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.
Air moves through the exhaust ducts due to two simple laws physics:
- Warm air rises
- 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, the draft is stronger because it is warm room air moves up the exhaust ducts. In summer, there is no temperature difference, the draft is zero - and air exchange practically stops. - Vertical distance between room and roof
At the top, the pressure is lower than at the surface of the earth. Therefore, the higher the exhaust channel ends, the greater the pressure drop. And that means more traction. - Wind speed and direction
Wind occurs when atmospheric pressure is unevenly distributed. If there is a zone of high pressure near the windows, and at the exit from exhaust pipe there will be a zone of low pressure, then the air will easily enter the house and easily go outside.
We cannot control the wind, pressure, or temperature outside the window. This is the main disadvantage of natural ventilation - dependence on weather conditions.
But there are a few tricks that will help you properly do 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 built house with a final renovation.
2. Ventilation pipe
It is necessary to search with the marking d125. Some believe that if you put a 125 pipe in a 132mm hole, there will be a large gap. This is not true. The diameter of the ventilation pipe is indicated internal. The wall thickness is about 1.5mm, there will be a slight gap, about 2mm on each side. It will be closed with an outer grille.
3. Outer grille
We recommend installing a metal one. As you may have guessed, all elements with a diameter of d125. If you want to install a plastic one, then look for one made of weather-resistant plastic, otherwise, under the influence of sunlight, it will quickly collapse: in just a few months it will lose its rigidity and break at the slightest touch.
Metal 350r, weatherproof plastic 150r
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4. Check valve
It is necessary that at the time of gusts of wind it protects the ventilation duct. Position it closer to the street side, with the axis horizontal.
You will need to cut the ventilation pipe (), insert a check valve, then.
1 valve - 90r
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5. Exhaust fan
We recommend Silent 200 CZ. It has a long service life, its plastic is safe for health, it has a reliable wire connection, high performance corresponds to the real one. Another big plus is that it is quiet. See the video below for the fan test.
Among the shortcomings, one can note the high cost, BUT, having saved 500 rubles, you can buy a fan whose performance does not match the declared one! It is better to install high-quality and reliable fan which will last for many years.
Fan flange outer diameter 120mm. We wrap it (25r) several times so that it sits tightly.
What's the downside?
The fan must not be turned off winter period. It must work 24/7, otherwise, when turned off, both the fan and the ventilation duct will freeze. To prevent the channel from freezing, you need to install 3 valves. It works like a vestibule in the entrance. System of 3 check valves creates 3 buffer zones for air, and the temperature difference becomes smoother. You can put 2 valves, but in practice only 3 valves completely eliminate the possibility of freezing. The Silent 200 will not be able to push airflow through 3 valves, a high pressure fan is required which is more expensive.
3 valve design
The Vort Quadro Micro 80 fan creates the necessary high pressure of 265Pa (even more than the Micro 100 model), so the airflow will push through 3 valves. For comparison, Silent 200 - 82Pa, fans for 1000r in household goods - about 25Pa. Valves should be placed as close as possible to each other, but so that they do not interfere with opening.
What's the downside?
The high cost of the fan
How to connect a kitchen hood?
Option number 1
If the hole made is the only exhaust ventilation duct, then it is better not to attach a kitchen hood to it, but leave it to be removed by a fan.
The task of the hood is to get rid of fat and unpleasant odors in the air. Polluted air can either be removed from the room or purified. Modern hoods have filters that do a good job of cleaning the air: grease filters effectively remove grease, carbon filters remove unpleasant odors. Therefore, now the hoods have a recirculation mode, when the air is not vented to the ventilation duct, but gets cleaned back into the room. There is a minus of the recirculation mode: you need to change the carbon filter every six months, they cost about 1000 rubles.
Option number 2
Extend the air duct.
Cooker hoods cannot be kept on all the time, so a system of 3 valves is needed to prevent freezing when turned off. Their hoods are easy to open, inside them is a powerful centrifugal fan. You need to connect the channel with plastic ventilation pipes d125. You can reduce the noise when working in the duct by wrapping in (575r). Unlike isolon, it has an adhesive surface.
Hole in the wall itself
It's pretty tricky to do, but it's possible. To do this, you need a puncher, a few days of free time and the hands of a hero. In fact, this is not an easy task, if you have never made such a hole, it is better not to start drilling bearing wall at home. Unlike diamond drilling, when working with a perforator:
- a lot of dust is formed, which will cover the whole room.
- the hole will turn out to be uneven, so you will have to dilute the cement mortar and cover up the voids.
- a funnel is formed at the exit photo No. 1
- you can burn the drill
Finding drillers with diamond drilling equipment is not difficult, look at Avito in your city.
Average price 3000r
If you want the drilling work to take place in the kitchen without dust and dirt, order drillers who are engaged in home ventilation. Base of ventilators. As a rule, there are builders on Avito who are used to drilling in houses under construction, ventilation workers in apartments with ready repair, so they have optional equipment to collect dust and dirt when drilling walls.
The average price of drilling without dust and dirt is 4000 rubles
By the way, before you start drilling the wall, ask: “At what angle will the hole come out?” The angle must be 0 degrees for the valves to close completely, otherwise they will hang ajar in the air.
How much does it cost to make a hood through the wall to the street, total.
If you want cheaper, with a fan that will not turn off, then materials + drilling a hole without dust and dirt will turn out to be about 8500 rubles, based on average prices in Central Russia. Taking into account the fact that you yourself mount and travel around the shops in search of the necessary components. Large chain of stores ventilation equipment called "Blagovest", there you can find most of what you need.
With the ability to turn off the fan, it will turn out to be more expensive - about 11800r.
With the connection of a kitchen hood 5000r + 480r for each meter of soundproofed air duct.
REMEMBER! If you have in your kitchen geyser, then you can not put a mechanical hood! A reverse draft may form in the gas column, and then carbon monoxide will go into the room. For this reason, tragedies with a fatal outcome occur every year. Norms are written by engineers for a reason, they are written in someone's blood.
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