Ventilation restoration: causes of reduced efficiency and duct restoration

Proper organization of ventilation not only provides an influx of fresh and outflow of exhaust air, but also minimizes the risk of mold in the apartment. However, over time, even a clearly functioning system fails, signaling problems with unpleasant manifestations.

Despite the causes of the failure, ventilation must be restored in a timely manner - after a comprehensive check and assessment of the condition of the ducts. And how to properly check and what you should pay attention to - all these issues we will consider in our article.

We will also analyze in detail the main reasons that affect the decrease in the efficiency of air exchange. We will supplement the material with visual diagrams and thematic photos.

Signs of decreased ventilation performance

In apartment buildings and private houses, the qualitative composition of the air, as a rule, is maintained by the operation of the supply and exhaust ventilation system with natural circulation.

Fresh air is supplied by windows, vents, doors or special valves. Removal of waste masses - through exhaust ducts installed in the kitchen or in the bathroom.

Naturally motivated operation of the ventilation system is based on the principle of traction, which arises as a result of wind pressure and the temperature difference between the outside and the inside of the house

With sufficient air circulation, few people think about the design of an air exchange complex.

These issues become relevant with the appearance of the first signs of deterioration in ventilation:

• high humidity and stale air;
• the appearance of condensation on the windows, “black dots” on the slopes, mold on the walls, primarily in the corner and behind the furniture;
• after airing into the room it quickly becomes stuffy - the windows constantly have to be kept in the “micro-ventilation” mode;
• reverse thrust with extraneous odors coming from the neighbors - the air stream rushes into the apartment, and not into the ventilation duct;
• dust quickly accumulates on furniture;
• kitchen scents spread throughout the apartment.

In addition to external manifestations, there are indirect signs of a lack of clean air. Households begin to complain of poor health, the appearance of unexplained drowsiness and fatigue. For a comfortable stay, the air in the room must contain at least 21% oxygen.

In the absence of ventilation, the concentration of carbon dioxide, harmful substances and dust increases. Oxygen deficiency causes headache and sensation of stuffiness

These factors indicate a malfunction of the ventilation system and are the basis for checking the efficiency of ventilation ducts. It is necessary to establish the cause of the failure in a timely manner and determine the way to restore ventilation.

Causes of deterioration in ventilation and solutions

Malfunctions in the functioning of natural ventilation occur for the following main reasons: reduced duct capacity, blocked air flow, or “equalized” temperature inside and outside the building.

We will analyze each cause and possible ways to eliminate it in more detail.

Problem # 1 - malfunction of the ventilation shaft

Insufficient draft of the ventilation shaft is most often due to clogging of the channel, narrowing of the duct section or its complete overlap.

An impressive layer of dust is deposited on the walls of the ventilation duct over time, the air duct is overgrown with cobwebs. Litter accumulated over many years leads to a narrowing of the mine - the volume of exhaust air is reduced. In addition, clogged ventilation can cause a fire.

Deposits on the surface of ventilation ducts worsen indoor air quality, since dust is a favorable environment for the development of pathogens

Sometimes the clogging of the mine occurs through the fault of unscrupulous apartment owners or employees. Without thinking about the consequences, some builders throw off part of the garbage into the duct.The narrowing of the channel is accelerated by the irreversible processes of shrinkage of the foundation, deformation of walls and ceilings.

The solution to the problem is obvious. It is necessary to determine the degree of contamination and perform ventilation duct cleaning. You can independently handle the exhaust hole from the side of the apartment. Deep cleansing is performed by masters using special equipment.

Often, the tenants themselves become the culprits of a sharp decrease in ventilation efficiency. During the repair or redevelopment of the apartment, some "craftsmen" block the ventilation ducts: they install built-in furniture or narrow the exhaust vent at their discretion. Inadvertent actions lead to a halt in air circulation or reverse draft.

House ventilation device with a vertical common channel: air from each apartment through a separate "sleeve" enters the main shaft and is led outside

The greater the number of storeys of the house and the number of supply channels, the stronger the draft. Accordingly, if you remove any element of the exhaust system from the chain, the draft weakens. With the simultaneous blocking of several "sleeves" at once, the flow power is not enough to lift and push out the exhaust air.

As a result, the opposite effect occurs - air flows rush down and fall into apartments mainly on the upper floors. To prevent back draft, exhaust ducts of the last floors are led directly to the attic. However, this does not solve the problem of insufficient air flow in the ventilation shaft.

The problem is especially acute in homes where the ventilation duct passes through the kitchen. In an effort to free up the usable area, the unfortunate craftsmen completely or partially cut off the duct. The “modernization” of space leads to unpleasant consequences for neighbors.

Sectional ventilation duct: one large (about 30 * 60 cm) and two small (about 15 cm) channels. A common mine runs along all floors of the house

Air with "aromas" enters the channels of the bathroom and kitchen. After passing about 3 meters, he gets into the mine. Thanks to such a device, spent steam does not seep from the upper floors to the lower ones, and prevents the penetration of the kitchen child into the bath, toilet and living rooms.

After trimming the part of the box, the shaft narrows substantially, and a small fraction (about 30-40 cm) remains from the three-meter “sleeves”. As a result of the alteration, the air coming from below abuts against the barrier and excessive pressure is generated - part of the flow rises upward, and part - to the nearest ventilation window.

Residents of an apartment located a floor below suffer most of all. In the warm season, exhaust air flows go down 2-3 floors

The solution to the problem is reduced to the following actions:

1. Invite a specialist for an expert analysis of ventilation efficiency.
2. Get an opinion on the diagnosis. The document should indicate the level of air exchange, the probable reasons for its reduction and recommendations for improvement.
3. To oblige the owner of the apartment, which blocked the exhaust hatch, to restore the ventilation duct. The request is issued by the supervisor or by court order.

After the restoration of the duct, the owner of the apartment receives documents for handing them to the housing inspectorate, BTI, court, DEZ and other authorities.

Problem # 2 - high tightness of the room

According to SNiP, a full flow of air during ventilation with natural motivation occurs through leaks in the external fencing, mainly window filling.

A sufficient amount of fresh air enters through the microcracks of the wooden window frames. The inflow maintains traction in the exhaust ventilation ducts and ensures uninterrupted air circulation

In the era of "European-quality repair", this dogma requires revision.Replacing old double-glazed windows with PVC window systems and installing modern doors block the flow of air. The new generation structures are characterized by high tightness, due to which the problem of heat preservation and sound insulation is solved.

However, clogging of the supply ducts leads to a malfunction in ventilation. Feeling stagnant, increased humidity, the appearance of dampness and mold.

Ways to solve the problem:

• operation of windows in micro-ventilation mode;
• setting supply window valve or its wall variety.

The first option is implemented on most window blocks. The sash position adjustment mechanism is mounted in profile during window assembly. The fittings are controlled by turning the handle 45 °.

Slotted ventilation allows you to open the glass by 2-4 mm, providing the lowest possible air flow. Cons of micro-ventilation: exposure to dust, street noise and room cooling in winter

A more effective method of restoring circulation is to install a supply valve. Window and wall air inlets normalize the air speed in the room, while maintaining the microclimate (temperature and humidity) normal.

The main condition for the supply valve operation is the existing exhaust ventilation. Street air through nozzles enters the room and rushes to the ceiling under the influence of convective flows

Each type of supply valve has its own characteristics. Window models are easy to install, but their performance is not always enough to fix the problem.

And here wall inlet valves more effective, however, for installation, you need to make a through hole in the wall. Errors in the installation can cause freezing of the duct or wall.

Problem # 3 - the influence of external factors

Ventilation is effective when the outside air is colder than inside the house. In winter, warm room air penetrates the exhaust ducts faster - intensive circulation is carried out.

High outside temperatures in summer can cause air stagnation or back draft. There is no prerequisite for the natural influx of air masses - a temperature difference at which cold streams replace warmer ones. That is why when the street is warm and humid, mold most often appears on the walls of the bathroom.

Solution to the problem: mounting a fan in the bathroom or in the kitchen to provide a forced draft.

To control the fan, the devices are equipped with automation: timer, motion sensor or humidity. Some models turn on and off by cotton

Diagnostics of performance and efficiency

Checking the operation of ventilation solves the following tasks:

1. Analysis of microclimate parameters and its compliance with sanitary standards.
2. Identification of malfunctions in the operation of the exhaust and supply component of the system.
3. Develop a troubleshooting plan.

The organization of the inspection includes visual, tactile diagnostics, as well as marker and instrumental control of air flow.

Inspection of the room and hoods:

1. Check window frames, walls in corners and behind furniture. Wet surfaces are a clear signal of insufficient air circulation.
2. Assessment of the supply ability of the system. Bring a wet palm to the window frame - the feeling of a draft indicates the serviceability of the supply duct. Similarly, the operation of the exhaust opening is checked.
3. Control odor removal rate. Leaving the windows closed, leave the apartment for 30-40 minutes. If, on return, the kitchen smells of food or the "aromas" of the garbage can, then there are problems with ventilation.
4. Check the external grille of the exhaust duct. Banal clogging of ventilation openings can greatly reduce exhaust draft.

For further research, the grill must be removed, cleaned and reinstalled.After manipulations, the pressure in the ventilation shaft should increase.

Sometimes, with a good ventilation system, the cause of “aromas” is neighbors. In this case, installation of such a simple but effective device as check valve for ventilation.

Removing the grill will allow you to visually assess the condition of the duct. Sometimes the mine is so polluted that dust and debris accumulated over the years pours right into the apartment

Testing traction experimentally:

1. Open the window in any room to ensure the flow of air masses.
2. Bring thin paper to the ventilation duct grille.
3. Rate the result. If the sheet is held and does not move, then the traction is sufficient and the hood works properly. If the paper is tilted in the opposite direction, we can talk about reverse traction.

The sheet is attracted to the grate if you attach it close to the wall. When removed 10-15 cm from the duct, the traction force is about 5% of the actual value.

It is not permissible to use an open flame to check traction - this is unsafe. There is a risk of ignition of combustible substances accumulated in the ventilation shaft.

Instrumental measurements allow you to objectively assess the effectiveness of supply and exhaust ventilation.

Conditions for obtaining validation data:

• the temperature difference between the internal and external air is not less than 13 ° С;
• outdoor temperature - not higher than +5 ° С.

An anemometer is used for diagnostics - the device shows the air velocity in the ventilation duct. The readings obtained by measurements are compared with normative speed air in the duct.

Measurement Algorithm:

1. Slightly open the window.
2. Release the exhaust outlet from the grill.
3. Turn on the anemometer and bring the device to the channel.
4. Read the readings.

The minimum speed of circulation of air flows in a common shaft is 5 m / s, in ducts - 3 m / s.

The obtained values ​​are compared with standard indicators and are used to determine the volume of air exchange

Settlement formula:

Q = V * S * 360,

Where V - measured air velocity (m / s), S - section of the ventilation duct (sq.m).

According to the accepted standards, at least 60 cubic meters / hour should go out through the hood in the kitchen, and from 25 cubic meters / hour in the bathroom.

Do you want to check the ventilation yourself, but have never done it? We recommend that you read the step-by-step instructions for checking the operation of the channels.

Methods for resolving ventilation defects

The method of restoring the efficiency of the ventilation system depends on the reason for the decrease in its efficiency. Some solutions to problems can be implemented independently. However, a number of issues require the involvement of professionals and the use of special equipment.

Self cleaning duct

Cleaning the common house ventilation line to which the side branches are connected is the task of the public utilities. They are required to conduct routine checks and maintenance of the ventilation system twice a year.

Residents are not allowed to carry out any manipulations with central engineering systems. The maximum that an apartment owner can do is clean the ventilation duct from the side of your home.

The first step is to remove the grate, clean it and rinse under running water. It is permissible to use neutral detergents to flush the ventilation grill. No chemical substances can be used inside the channel.

Remove accumulated dirt and greasy crusts formed around the perimeter of the hole with a sharp knife or comb it with a stiff brush. Vacuum the duct, wipe the duct as far as possible and replace the cover

To clean the ventilation duct, a flexible steel cable with a ruff for servicing chimneys is deeper. Insert the structure into the duct opening and scrape the ruff of pollution from the walls. Remove residual debris from the channel with a vacuum cleaner.

Care must be taken during operation. In ventilation shafts there may be hornet's nests, inhabit other insects or animals

If the measures taken did not improve the exhaust draft, then the main shaft is clogged. To clean it, you must invite a special service.

Restoring the ventilation riser

Spontaneous alterations involving the ventilation duct will have to be fixed sooner or later. Understanding the structure of the duct, its restoration will not cause special difficulties.

Ventilation "sleeves" have a round or square section. Initially, their walls are made of concrete. During reconstruction, satellite channels can be made of corrugated pipe or delimited by a foam block

In the estimate of upcoming work, it is necessary to lay the cost:

• material for enclosing the ventilation duct (foam block, drywall, plaster blocks or OSB sheets with fire protection);
• corrugated pipes for ventilation ducts coming from the kitchen and bathroom;
• cement-sand mortar or finished adhesive for masonry foam block;
• plaster and finish box.

To restore the kitchen duct, gypsum boards or foam blocks are optimal. Building materials have the necessary strength, impermeability and fire resistance. In addition, the plates provide adequate sound insulation.

Restoring the ventilation riser is carried out in several stages.

Stage 1 - preparing the premises and opening access to the mine

The kitchen should be freed as much as possible - to take out furniture, utensils, light household appliances. Fitted wardrobes, cabinets, equipment and floor with polyethylene.

To open access to the shaft on the wall and on the floor, you will have to mark it according to the dimensions of the future box. Remove the tile, concrete screed and open the air duct.

Dismantling the floor is done carefully so that construction debris does not clog the ventilation ducts. As a result of the work, a mine and two satellite channels open

Stage 2 - restoration of side walls and partitions

The lateral and front sides of the duct are laid out corresponding to the previously dismantled structure. Companion channels are separated from each other and from the general shaft by foam blocks. At the same time, the cross-sectional area of ​​the "sleeves" necessary for the free passage of air is preserved.

Reconstructed duct fully meets the requirements of natural ventilation - air flows coincide with the directions provided in the design documentation of the house

Stage 3 - ventilation check and decoration

To assess the effectiveness of the ventilation system, it is better to invite a specialist. In any case, he will be required to conclude an act of acceptance of the work performed.

Decorative design. If the air circulation does not raise questions from the part of the supervisory authorities and there are no complaints from the side of the neighbors, then you can safely take up the finish of the box.

An alternative way is to use a corrugated pipe. The new satellite channels from below are connected to the old ones using concrete pouring and are additionally fixed on the plasterboard partition separating the "sleeves" from the common shaft

Conclusions and useful video on the topic

The operation of the ventilation system of an apartment building, the reasons for the decrease in efficiency and the solution to the problem:

Restoration of the ventilation duct using foam blocks and metal pipes:

Prerequisites for the appearance of reverse thrust and methods for its elimination:

Regular checking of the ventilation system’s performance and preventive cleaning of the air ducts will help to avoid unpleasant consequences: dampness, damage to the walls and deterioration of well-being. Uninterrupted operation of supply and exhaust channels is the key to a healthy microclimate.

Have you found a decrease in ventilation efficiency and want to identify the cause and eliminate it yourself? Maybe you have problems determining the cause or want to consult with our experts about a solution?

Or maybe you are professionally engaged in arranging ventilation systems, cleaning channels and restoring ventilation and want to supplement the above material with useful tips and important nuances? Write your comments, ask questions, add photos - your activity will help beginners to better understand the topic of the article and solve their problems with ventilation.