Any apartment building has a ventilation system. She is responsible for the flow of fresh air into the room and the removal of stagnant air. But situations can occur when dirty air flows back into the house. This phenomenon is called reverse thrust. It interferes with the comfortable life of people, and also carries a potential danger. You can correct the situation with your own hands when there is no malfunction of the system itself. In other cases, you need to contact a special service.
Reverse thrust definition
Draft in the ventilation system is understood as a directed flow of air masses, which occurs when there is a difference in pressure in the house and on the street. The air flows naturally go to the low pressure area. By this principle, general house ventilation works. First, the air heats up, its density and mass decreases. It goes up and out into the vent. Fresh cold air comes in through the cracks and fills the entire space.
The thrust force is directly related to the height between the air inlet and outlet. For this reason, the residents of the upper floors feel the lack of fresh air more acutely.
The phenomenon of reverse draft in the ventilation of an apartment in an apartment building consists in the impossibility of removing dirty air. He goes back to the rooms and brings bacteria and unpleasant odors with him. You can understand that the system is not working correctly by the following signs:
- Fogging windows, condensation, mold and mildew. Excess moisture is also removed through the ventilation. If the system does not work properly, water will not be drained and will begin to settle.
- Stuffy stuffy air, often accompanied by an unpleasant odor.
- Draft from the air vent. If you bring your hand to it, you can feel what is blowing from the ventilation into the apartment.
The simplest test can be done using a regular sheet of paper. You need to attach it to the ventilation hole and see the direction of the oscillation.
Natural air circulation in the house
The ventilation system in the house is a complex of various technical devices, blowers and shafts, which have a single riser from the basement to the roof. Thanks to him, traction is created due to the temperature difference in the house and on the street. As this difference increases, the hood will work harder.
The effect is also exerted by the perpendicular pressure according to the principle of cross sections. This is a situation in which the wind blows horizontally in relation to the riser. As a result, it draws air out of the ventilation.
So that there is an air flow in the house and a vacuum does not form, vents are made in the foundation at the construction stage. It is also possible to make some holes in the floor on the ground floor.
Thus, the natural circulation of air in an apartment building works. The system may not work if there is no supply ventilation or if the temperature in the house is lower than outside. The second reason does not occur often, therefore, it is precisely because of the lack of decent air flows that thrust appears. Ventilation shafts in the apartment are made in the bathroom, toilet and kitchen. Air enters through the windows.The use of double-glazed windows and sealed doors significantly reduces the inflow of air masses and causes reverse draft. To solve this problem, special valves are used for windows or walls.
Also, a violation of the air flow can be caused by a malfunction of the system, the installation of fans and hoods, and improper design. If the hood blows in the opposite direction in the apartment, you need to look for the problem and fix it.
Reverse thrust reasons
The main reason for the occurrence of reverse thrust is the violation of the principle of natural air exchange. It is caused by the following factors:
- The use of plastic windows and sealed doors. They are able to completely block the access of fresh air to the room.
- Alteration of the ventilation duct or illegal demolition.
- Incorrect pipe design or incorrect location. If it is installed in the wind shade zone, circulation will be disrupted.
- Change in wind direction.
- Clogging of the ventilation duct with small debris, birds entering it.
- Constructive errors.
To identify and eliminate reverse thrust, you should contact a specialist. It is better to choose independent experts who will conduct a comprehensive analysis of the entire air duct system in the building and give recommendations on how to improve the situation.
System check
A check is carried out to identify and eliminate faults. It consists of the following steps:
- Study of design documentation. Checking its compliance with the norms and standards of GOST.
- Evaluation of the effectiveness of the installed equipment, the correctness of its installation and operation.
- Checking the quality of the installation work of the duct, ducts and other elements of house ventilation.
- Air sampling.
- Search for unauthorized channel overlap.
On the basis of the test carried out, the specialists decide how to eliminate the reverse thrust.
Elimination methods
To remove the backdraft, the ventilation system must be brought into operable condition. The main ways to restore work that you can do yourself include:
- Check valve installation. The device will not allow old air to return to the room again.
- Installation of supply valves on windows. Thanks to this mechanism, fresh air will flow into the house, even if the window is closed. The intensity can be adjusted. Also, the valves can be equipped with fans, debris grills and other attachments for cleaning, heating and cooling air masses.
- When installing a powerful hood, it is necessary to balance it in terms of performance. The volume of the incoming air must be equal to the displaced one.
If the weather conditions are the cause of the draft, you need to wait until the normal temperature and humidity values, as well as the wind direction, are restored. Such factors are temporary and do not depend on the person. With frequent influences of weather conditions, you need to think about redeveloping the system.
If damage has occurred due to which the hood blows in the opposite direction in a private house, you need to call the repair service. Experts carry out the following activities:
- Protect the mouth of the mine if draft is generated by strong gusts of wind.
- Restore damaged structures, make their repair or replacement.
- The channels are cleaned. It must be carried out at regular intervals. Do not clean the ventilation yourself.
It is not always possible to correct the factors affecting traction. For example, the features of the layout of the room may be such that stagnant air will return to the room. In large rooms without walls and partitions, drafts will appear, which affect the overall ventilation system in the house.Stagnant air masses can also return from the stairs to the second floor.
If the reason was the wrong design of the ventilation duct, you should rework it.
Preventive measures
Troubleshooting a backdraft problem can take a lot of effort, time and money. To avoid this, you need to take preventive measures. Basic tips:
- The system must be in good working order.
- Fans and hoods should not be placed in ventilation ducts. It is possible to use only recirculating hoods or to discharge them outside through a wall or window.
- Deflectors and rotary turbines are placed at the end of the riser.
- Organization of the inflow of fresh air from the street in any available way, including in winter.
- Installation of interior doors to block the possibility of a draft that affects back draft.
- Cleaning the system from ice and snow in the winter.
- Periodic ventilation check.
These measures will help to avoid most of the problems due to which reverse draft is formed and cold air blows into the apartment from the ventilation.
Where to go
The ventilation of the apartment building is shared. If there are problems, reverse thrust will appear in all apartments, so you need to act together. First of all, you need to discuss the problem with all the residents of the entrance. Perhaps a very powerful hood is installed in one apartment, which harms the operation of the entire system.
Next, you should contact the management company with a request to find and solve the problem. In the event of the appearance of cold musty air, you can contact the gas company. This decision is due to the fact that ventilation is a security system. It is the presence of reverse thrust that does not make it possible to ventilate the room from energy carriers and products of its combustion.
If reverse thrust appears in the house with a certain frequency, and it is impossible to eliminate it, part of the windows should be replaced with anti-explosive ones.
