Ventilation systems are an integral part of the house, which allows the removal of unpleasant odors and odors and ensures the circulation of air flows. In this regard, the phenomenon of reverse draft in ventilation is a big problem for residents of high-rise and high-rise buildings.
Due to this defect, unpleasant odors appear in the house, which residents immediately feel. What to do if the ventilation blows into the apartment? The solution to such a problem should not be postponed for long, because the problem will not be solved on its own. The article examines in detail the reasons for such a breakdown, as well as ways to cope with this trouble.
Natural ventilation at home
What is this ventilation system? Essentially, this is a complex of air ducts in a private house or a system of shafts in an apartment building, in which there is one main riser stretching from the basement to the roof. It is this that creates the draft due to the temperature difference between indoors and outdoors. And the greater this difference, the stronger the hood works. Let's add wind perpendicular pressure like cross sections. This is when the wind blows in a horizontal direction relative to the riser, and it pulls air from the ventilation with it. That is, air is sucked out of the premises naturally, and not with the help of additional equipment such as a fan.
Of course, in such a system there must be an air flow 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 air circulation problems
If the ventilation system is not working correctly, there is a reason for it. There are many of them, but the main two are:
- There is no supply ventilation.
- The temperature inside is lower than outside. This usually happens in the summer when it is hot.
But the main reason is the lack of supply air flows. Typically, in apartments, outlets to the ventilation shaft are made through the bathroom, toilet and kitchen. And the air flow occurred through the windows (their leaks) and the front door. Today, when plastic windows are installed instead of wooden windows with complete sealing of joints and connections, the problem of inflow has become serious. Most often, backdraft appears because of this. This problem is solved by installing supply valves into window systems.
Other causes of traction failure and reverse flow include:
- malfunctions of the system itself;
- installing fans instead of grilles;
- installation of a flow hood, which is connected to the ventilation duct;
- absence of an umbrella on the roof or destruction of the mouth of the canal.
Installation of supply channels
Supply channels are holes that are made from the street side to create additional air flow directed into the room. The flow direction is controlled by two valves. But it is better if the valves are installed in advance in plastic windows to improve tightness and the possibility of normal air circulation.
Ventilation valve in window frame
Principle of operation
Each valve has a grille inside to protect against excess debris entering the room. And for sound insulation, a special box is installed on the outside of the hole.
You should choose only high-quality valves. Cheap models cannot function normally at large temperature ranges or air will pass through even when closed.
An important condition is the creation of a good indoor microclimate. For this purpose, cleaning filters, ionizers, and control systems are installed. The devices will allow air to be humidified and ionized for disinfection purposes.
Causes of ventilation malfunction
The causes of the malfunction can be attributed to a large number of factors. The main thing you need to understand is that when there is blowing from the ventilation system in an apartment, it is not the same thing if the same effect appears in a private house. That is, faults in two buildings may be different, because the traction failure in them has different causes.
For example, in an apartment this most often 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 pass the entire mass upward. That is, part of it ends up in the adjacent channel of the toilet or bathroom. It is in these rooms that the opposite effect occurs. The same thing happens in the opposite direction, if the fan in the kitchen is turned off and the fan in the toilet is on. This also happens with neighboring apartments located one above the other.
This suggests that you cannot thoughtlessly 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 of a multi-story building.
For this reason, this cannot happen in a private house, because at the design stage today they try to distribute ventilation ducts to all rooms separately. That is, the kitchen has its own riser, and the toilet and bathroom have their own. But sometimes another problem arises in the house. Most often, risers are combined into one or two common channels inside the attic, and then one or two pipes are discharged 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 air duct as possible, and to minimize the angle of inclination of horizontal sections (the reduction should be minimal). That is, the steeper this section, the better the upward air movement.
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 the cross section.
- Lack of an umbrella (visor), which can lead to rain and reduced traction. This disrupts air exchange.
- The ventilation in the house is clogged with debris.
So, in order to remove backdraft, you must first understand why it appears.
How to repair a kitchen hood with your own hands
If the hood functioned without failure for several years and suddenly broke down, there is no need to worry too much, but even if it has not lasted even a year, it is too early to panic. It is quite possible to fix many problems at home, without calling a specialist or sending them to a service center. The following types of faults exist:
Lighting doesn't work
- The light bulb has burned out. It is very easy to change to a new one, which any housewife can do.
- The backlight switch has become unusable. Checking the switch contacts will help.
Hood with backlight on
The hood has stopped working and will not turn on
- Lack of electricity in the network. The cable, plug, or socket may be damaged. It is necessary to make sure that there is voltage in the outlet, the integrity of the supply circuit and the control panel. If the problem is in the cable, it will be immediately obvious by mechanical damage and smell.
- The switch is faulty. The solution is to “ring” it with a multimeter and replace it if necessary.
- The fuse has blown. During voltage surges, these elements often burn out, damaging the entire structure.
- The motor is broken. One of the main reasons is often overheating of the device. As a rule, you cannot fix such a breakdown on your own. You will have to return the equipment for service or buy a new one.
- To prevent overheating, you need to pay enough attention to the cleanliness of the grease removal plates, clean them in a timely manner and change the filters.
Faulty motor
Insufficient draft when the hood is running
- The first step is to clean or change the filters, since the draft may be lost due to contamination with grease. The effectiveness of the device with a clogged filter is negligible.
- Disassemble the air duct pipe and make sure there is no debris or grease deposits.
- Check the air movement in the common house ventilation duct using a sheet of paper or fire.
- The reason probably lies in an unusable fan whose blades have broken. The way out is to replace the part.
Air draft check
Control panel malfunction
If the buttons are deformed or partially fall out, or the contact is burned out, you can try to re-solder the circuit or completely replace the entire button block.
Inability to change gears
The simplest reason is a button or slide switch falling out due to frequent mechanical impact.
You can disassemble and clean the contacts, but the most effective way is to install a new part. Quite expensive models of hoods have touch control, but for all its visual appeal, the sensor is very difficult to repair. In addition, you need to pay attention to the starting capacitor and the track on the control board. But for this type of work, at least minimal knowledge in the field of electrical engineering is required.
Push button speed switch
Causes of reverse thrust
As mentioned above, reverse draft in ventilation appears for two main reasons:
- Complete sealing of the premises.
- Installation of additional exhaust devices in ventilation ducts.
All other reasons are secondary, some of which do not create reverse draft, but simply the ventilation stops working. Ventilation in an apartment is more difficult, because the system itself is a complex set of channels, often made of concrete. Branches extend from the riser throughout all apartments, through which air from the premises must be removed to the street. And if a neighbor on the lower floor installs a powerful kitchen hood, then not only he, but also the neighbors on the floors closest to him will feel the reverse flow of air masses.
In a private house, reverse draft occurs for other reasons, because the ventilation in the apartment differs from the ventilation system of a private house. This is where installing fans can solve the problem. But you just need to determine the installation location using different risers.
Checking the result
To check the traction characteristics of the installed ventilation, you will only need to have a match with you. The check is done as follows: light a match and bring it to the switched on hood. If everything works fine, the fire will go out. If this does not happen, there is most likely a problem with the flow into the bathroom or apartment.
To solve it, it will be enough to install a supply valve in the room (wall or window). Also take care of the flow into the bathroom; for this purpose, door valves are installed in the doors.
Solving the problem using a fan
Many people probably thought that the conversation was about installing fans in place of ventilation grilles. Nobody 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. This may be a mechanical deflector or a rotary turbine. Both devices are powered by the wind, so they are of no use in calm weather. Although, as practice shows, it is the installation of these devices that sharply increases traction and prevents reverse flow.
As for fans on ventilation grilles, you should first calculate their power. It depends on the cross-section of the ventilation ducts and on such indicators as air exchange in the premises. For example, in the kitchen this figure should vary in the range of 12-20 m³/hour 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, a room area of 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 the minimum value, the fan performance is 432, at the maximum 720 m³/hour.
How to check the operation of the hood
If the windows fog up in the room and foreign odors remain for a long time, mold or mildew has appeared on the walls or ceiling, most likely there are problems in the functioning of the ventilation.
Let's look at how to check if the hood is working. To do this, take a small piece of paper. A toilet paper will do, but it’s better not to use regular newspaper, since a thin piece of paper is used for such purposes.
Open the window in one room by 5-8 centimeters and attach the leaf to the hood grille. If the paper is attracted, the hood works. If the leaf does not hold and falls, the ventilation has stopped working. In addition, the paper may fly off the grid.
This means that the hood works in the opposite direction, and foreign odors enter the apartment. Let's find out why it works incorrectly or poorly or has stopped working altogether. And we will find out what to do if the hood in the kitchen, bathroom or toilet does not work.
Preventive measures
What needs to be done to prevent backdraft from forming.
- Keep the ventilation system in good condition.
- Do not install fans or hoods into ventilation ducts. Use a recirculating hood or vent it outside the room to the street: through a wall or window glass.
- Install baffles or rotary turbines at the end of the riser.
- Organize air flow into the premises by any means.
- Install interior doors that block air movement between rooms. Strong drafts are also causes of backflow.
- Clean the ventilation system from snow and ice in winter.
- Check ventilation periodically.
Expert review
To obtain a professional assessment of the ventilation condition, you will need to invite an appropriate specialist who, after the inspection, will draw up regulatory documents where the system parameters are entered. The status report will include ways to address existing deficiencies.
The examination includes three stages:
- Study of project documents.
- Equipment check.
- Finding the reasons for malfunction.
A video endoscope is used to search for blocked wire paths. All identified deficiencies are eliminated within 45 days.
