Check valve for ventilation types of device installation on the hood. Ventilation check valve: purpose, types, installation Check valve for square ventilation

Modern ventilation systems are designed to effectively organize air exchange processes in different types of premises. At the same time, most devices and household appliances intended for ventilation of a house or apartment are connected to a complex of general exchange or natural ventilation.

For the high-quality functioning of all devices and to prevent the return of contaminated air mixture to the room, certain devices are used.

The presented photos of the check valve for ventilation allow us to understand the principle of its operation, and to evaluate the possibility of choosing different models for arranging a home air exchange complex.

Ventilation systems, their types and purpose

The need for ventilation of residential and utility or target premises is due to the importance of creating comfortable conditions for a person.

Waterlogging or dehumidification of space, unpleasant odors and a high concentration of dust can lead to the development of various diseases, so different air purification systems are installed:

general exchange. Natural ventilation, provided by the physical process of air exchange, which occurs due to the difference in air pressure located outside and inside the building;
forced. It is provided by the operation of supply, exhaust or supply and exhaust type equipment, which enhances the functioning of the equipped general air exchange.

An effective check valve in the ventilation system ensures that the occurrence of such an effect as reverse draft is neutralized.

This rather unpleasant phenomenon is the result of various reasons, and its consequence is the return of the contaminated and exhausted gas-air mixture through the ventilation shafts.

Reverse thrust: causes and features of occurrence

An equipped and properly installed do-it-yourself non-return valve for ventilation will help to avoid the entry of dirty air from the air outlet shaft into the house.

This phenomenon is often observed in old houses, in addition, there is a whole range of reasons that cause an unpleasant effect, these include:

reduction or blocking of the air flow from the supply ventilation system;
gradual and complete clogging of the outlets in the complex of natural air exchange;
failure of mechanical elements and components of forced ventilation equipment;
increase in general exchange processes as a result of multiple cutting into the ventilation shaft;
improper design and distribution of air intake points around the house or premises.

It is important to understand that even with operable and adjusted complexes of general exchange and forced ventilation, reverse draft may occur.

This happens during sudden weather changes, this condition is caused by pollution or icing of the outlet channels and a violation of the general architecture of the building.

Reverse thrust neutralization device

Supply or exhaust ventilation with a non-return valve neutralizes the negative effect and the possibility of returning air to the room.

The process of closing the air duct is carried out due to natural physical laws and thanks to the unique structural device of an effective device.

Types of check valves for different ventilation

Modern manufacturers offer a non-return vent valve for natural ventilation and models suitable for other equipment.

At the same time, such devices are divided according to design features into different types, which have their own operational characteristics:

Membrane. Single-leaf device with a flexible membrane for air flow in one direction and blocking of the movement of the reverse type. These devices differ in internal design and can be with an offset axis or equipped with a counterweight.

Petal. Compact and small models in appearance resemble blinds and are often used in ventilation systems.

The plates of such devices easily respond to the movement of air masses due to their flexibility and block the reverse movement of air.

Butterfly. A simple and effective valve is placed in the air duct to increase the efficiency of the ventilation complex and works like petal models. A feature of such a device is the presence of not many flexible obstacles, but two petals.

The simplest and least expensive solution for a natural type air exchange system is a grille with a check valve for ventilation. It is recommended to install such devices at each entry point to a common ventilation duct that discharges the exhaust gas-air mixture outside the premises.

Photo of the check valve for ventilation

The check valve for ventilation in the apartment allows it to work efficiently, especially in the kitchen and bathroom. It is installed in both natural and forced systems.

Such a device can be bought in a store, but more and more residents make it with their own hands. The installation process is simple and does not take much time.

In this article, we will consider information about what a check valve is used for in ventilation, its purpose, types and installation by specialists or do-it-yourself. After installing such a device, you can forget about any odors in your apartment.

What is a check valve for?

The non-return (anti-return) valve is a design in which the blades of the valve itself located on the axis will move in such a way that the air entering the valve will not enter the apartment.

The air masses in the check valve move only in one direction, and if it changes sharply, the device closes, which prevents air from entering the room.

Absence - it can be broken or clogged, in connection with which the supply air simply does not enter the ventilation.
Incorrect location of the exhaust pipe, as a result of the ingress of blown air into the ventilation.
Stove heating is installed in the house, and when the stove is operating, the combustion draft in the pipe increases, which contributes to the reverse flow of air in the ventilation pipe.
In one of the apartments of a multi-storey building, a powerful one is installed, and during its operation, the course of air flows in other apartments is disrupted.
The presence of several hoods in one apartment will increase the draft in one of them, which will lead to a violation of the outflow of air.

To check the presence of draft in the ventilation, you can use a candle. Bring a lit candle to the ventilation and open the window. If the air flow is correct, then the candle will die out.

As it has already become clear, the check valve is an important element of the ventilation system. This is a special blade, which has such a diameter that it completely covers the working module from the back, and it is mounted on the fan axis.

The damper is specially designed to prevent back draft, that is, air that has already been drawn out of the room, or air flow (from the street, ventilation duct, etc.) along with other contaminants.

The purpose of the check valve is to reduce or increase the cross section of the ventilation duct. Depending on the task assigned to the check valve, there is a greater or lesser influx of fresh air or an outflow of polluted air masses.

But the main task, nevertheless, is to prevent the influx of foreign odors into the living quarters, which can penetrate for various reasons - clogging of ventilation ducts, their poor tightness.

according to the material of manufacture;
in form;
according to the way of functioning;
at the place of installation;
by the ability to pass a certain amount of air.

According to the material of manufacture, they are made of metal and plastic, the shape of the check valve can be round or rectangular and depends on the design features of the ventilation system itself, the shape of its section.

Plastic and metal are materials of different qualities, so valves made from them are used in various ventilation systems, depending on the conditions and design features of the latter.

According to the method of controlling the ventilation device - automatic and manual. Automatic devices can be controlled, almost without human intervention, using microcircuits.

Manual control is used in simple ventilation systems where the amount of air flow and time is controlled by simply opening or closing dampers.

Ventilation grilles with a non-return valve are an excellent solution in exhaust ventilation systems. The bottom line is this: polluted air is forcibly moved out of the room through the ventilation duct, and with its pressure raises the valve.

In the absence of pressure, the valve lowers under its own weight and prevents air from entering the room from the outside.

It is easy to guess that this is not about natural ventilation, but only about mechanical, forced type. Although the damper is designed so that it opens and closes easily, the natural flow of air is not able to lift it. Unless in the presence of a huge force of drafts, which is not possible in a house or apartment.

The main difference from a similar analogue - inertial gratings - is the need to use forced ventilation. As a rule, such structures are most often installed at the outlet of the ventilation shaft under a conventional kitchen hood.

flange for connecting the air channel;
fixed part (lattice);
moving part (damper-valve).

The cross section in which such structures are presented is usually rectangular, but there are also round options. The vent flange is always round. The difference is only in the diameter, which can be from 110 to 150 mm.

The fixed part performs two functions: decorative (partially hides the valve) and protective (protects the moving part from the mechanical impact of something).

The damper itself is presented in the form of a rectangular or round petal, which opens in one direction. The connection to the main body is movable, but without involving any metal parts. This is done specifically in order to avoid metal corrosion and, as a result, jamming in the open or half-open state.

The material from which such a ventilation grill is made is plastic. Since the structure is often located in a zone of high humidity, the use of metal moving and fixed parts is not recommended.

However, in everyday life you can find home-made gratings made of galvanized steel. But no one can vouch for their durable and trouble-free operation.

Petal. They are made in the form of a rigid damper fixed on an axis and contain the principle of operation of the rotary mechanism. With the flow of air masses, this flap rotates, thus closing or opening the air inlet.
With gravity grid. Outwardly, they resemble blinds, located vertically or horizontally. When the hood is turned on, the shutters open and begin their work. This type is installed in the walls to protect communications.
Membrane. They work on the principle of petal valves, however, the damper in such devices is much thinner, and when the wind blows, the membrane closes the grille, thereby preventing air from entering.
Butterfly. Similar in structure to the petal type of the valve, however, it has two petals on the axis, which resembles the well-known insect. When the ventilation is turned on, the petals open and, accordingly, when turned off, they close.

In addition, the valves are of horizontal and vertical type, with and without heating, as well as rectangular or round.

Fans with a check valve are divided by type into axial and centrifugal. Their main characteristics that you need to pay attention to when choosing are: air consumption in cubic meters per hour, power consumption in watts and noise level.

Different models can be switched on periodically, at will, or work constantly. They have check valves made of plastic, metal or thin film; they also differ in location and shape.

Modern sophisticated design (manufacturers develop such devices not only reliable, but also suitable for any interior).
High performance and quiet operation.
Effective removal of moisture, dust, stale and exhaust air from the premises.
Waterproof execution.
The case is based on heat- or light-resistant plastic.
Low power consumption and long service life.
Simple wall or ceiling mounting, easy maintenance.
Reducing heat loss at home and increasing the energy efficiency of ventilation.
Manual or automatic control: switching on from a stationary or pull cord switch, by a humidity sensor, a motion or light sensor, by a timer, with an adjustable turn-off delay.

Thus, before you are going to buy a bathroom fan with a non-return valve, find out how the model works, whether it has sufficient performance for your room, what noise level and how much energy it consumes.

How economical and convenient is the control, what is the degree of moisture protection, what is the electrical and fire safety of this model, what are the features of installation and maintenance. This little device is responsible for a healthy climate in your home, so it's worth learning more about it in advance.

Household exhaust fan with non-return valve. Installation location is incorrect. Before mounting, it is important to carry out some calculations, take into account the height of the ceiling, the width of the walls, and so on. And only on the basis of these data you need to plan the installation.
The exhaust fan is mounted in the middle of the wall, not opposite the shower room. As a result, the hood does not affect the corners and a fungus forms there, and the direction in the wrong direction leads to uselessness, because bad air remains near the source of moisture.
The correct option would be to install the unit exactly in the corner with the direction to the bathroom / shower - this way we will eliminate the so-called 'dead zones' and capture the entire volume of the room, and the hood will work exactly from the side of the source of problems (all other areas will be cleaned using a hood with doors).

As a result, we have the following: you need to correctly approach the selection of a suitable fan, and take into account the features of your home, its location, and the installation of the fan.

To eliminate all the mistakes that the installer can make, it is best to order such work from a company that specializes directly in this equipment and has extensive experience with the installation of ventilation equipment.

The bathroom is a room with an elevated one. Natural ventilation for this room, in most cases, is not enough. An extractor hood with a non-return valve in the bathroom will help improve air exchange. An axial or duct (radial) fan is most often used as a forced exhaust device.

The axial fan is the most common impeller mounted on the shaft. The advantages of such a device are its simplicity, reliability and cost. The disadvantages include noise and low power.

Typically, such units are installed in small bathrooms, with a total cubic capacity of up to 15 m3. Also, such devices require a straight horizontal section of the duct with a length of at least 3 meters in order to ensure minimal aerodynamic resistance.

The duct fan is installed directly into the duct. It is quieter and more productive, but its price is somewhat higher than that of axial counterparts.

Constant ventilation mode. These models work all the time. They are equipped with an air humidity sensor. Depending on the readings, the speed of rotation of the blades changes. Despite continuous operation, such exhaust devices are quite economical.
Shutdown timer. Saves time and energy. Such devices do not require shutdown. After a set period of time, the fan automatically stops working.
Motion Sensor. Timer analogue. Only with this function, it is not even necessary to turn on the hood. It turns on automatically, and turns off after a specified period of time, after the last movement in the room.
Splash protection. A useful feature for the bathroom. Especially if the vent is located above the bath or shower. The minimum level of protection of the device must be at least IP5.

Separately, it is worth stopping at the check valve.

Ingress of exhaust air masses from the ventilation shaft into the room.
With a complex system of ventilation ducts, the valve will help regulate the direction and speed of the air flow.
In private homes, the presence of a valve will help reduce heat loss by preventing cold street air from entering the room.

Bathroom hoods with a non-return valve, made in a single design, are becoming more and more common. This is very convenient, since the valve installed on the hood is ideally suited in size, material and opening method to a specific model of the exhaust unit.

You can, of course, purchase the valve separately, but before such a purchase, you should consult a specialist.

With the wrong choice, this device can tightly block the ventilation duct when the hood is turned off, depriving the bathroom of natural ventilation.

First you have to dismantle the fan that you have successfully used. We install the non-return valve body in the ventilation hole and make marks on the places of the intended fasteners. The case is to be removed, and on the resulting marks you need to drill holes.

We return the case to its original place and through the holes we make marks on the walls of the well for ventilation. We remove the valve again, and holes will have to be made on the marks obtained.

You definitely won’t be able to use a puncher, so you have to use a jumper (a device for making holes in concrete bases mechanically).

We hammer dowels of the appropriate size into the holes. It remains only to return the check valve to its place and wrap all the fasteners until they stop. Pay attention to the resulting holes or gaps between the check valve body and the ventilation well.

If their size is visible to the naked eye, then the installation of the check valve will have to be supplemented with sealing. The simplest thing is to silicone all the gaps.

Note! This moment cannot be ignored, since the air draft will not be sufficient to close the valve shutters. This will not harm ventilation, but the valve will either not perform its main function, or will not be fully.

After completing all the described work, it is necessary to install the fan in its original place. On this, we can consider the mission accomplished: the ventilation will work reliably, the check valve will not let foreign odors into your house.

Currently, non-return valves have begun to appear on sale, which do not imply such drastic changes. Such devices are not mounted behind the fan, but directly in front of it. Such peculiar valves are overhead.

They work no worse than previously described. The only peculiarity is that the valve will protrude somewhat above the plane of the wall. With a well-designed case, this can be the easiest solution to ventilation problems, and will give this device a certain charm to the design of the room.

And it is also necessary to add a few words about the wide range of valves on the modern building materials market. The choice is very wide in various parameters. This is especially true for the valve body.

Manufacturers of all ventilation equipment understand that there are no universal sizes of ventilation shafts, therefore, to the maximum, it was decided to provide the entire market with goods in all directions.

There are check valves designed for various sections of ventilation wells. Check valves with a square section are especially reliable. Their peculiarity is that they are not afraid of various kinds of distortions and are very easily mounted in wells of any section. Such devices can reliably provide ventilation in any home.

Is it necessary to buy a ready-made check valve? You will have to solve this issue yourself. As you may have guessed, almost any man can make such a check valve.

It makes no sense to make more complex designs on your own, for the reason that it will take a lot of time and the costs will be disproportionately higher than when buying a finished product. The price difference for valves is quite noticeable. The simplest designs are ten times cheaper than more complex counterparts.

By the way, expensive non-return valves are not available in retail trade, as they are sold complete with fans.

This makes a lot of sense: the design of the damper is calculated for a specific fan model, so it will work perfectly in tandem with this fan. In another set, a mismatch can greatly affect the operation of one of the devices.

The installation of a do-it-yourself ventilation check valve is especially relevant for residents of the last floors of houses, where the problem of dragging "foreign" odors through the air ducts of the general exchange system is common.

Thick plastic or textolite is suitable for the base of the kitchen ventilation check valve. You need a plate with a size that covers the outlet of the exhaust duct and a thickness of not more than 4 mm. Markings are made on the plate: a grid the size of a fan hole, as well as holes for mounting to the wall (at the corners) and for mounting the fan.

The larger the grid cells, the denser the leaf material must be!

To prevent air from “walking” between the base and the fan, a rubber gasket is used.

To prevent not only reverse draft in the ventilation of an apartment building, but also the penetration of insects, a small plastic mesh or even a nylon from tights is attached to the base grate. The latter is easily replaced. And so that the residents are not disturbed by the vibration from the fan motor, rubber shock absorbers are used during installation.

Shutters are used from thick polyethylene (not less than 0.1 mm). The film should be perfectly smooth, the smallest waviness will break the tightness of the ventilation, and the reverse draft in the apartment building will resume. You can mount the sashes on adhesive tape with a fabric base.

We recommend cutting the sashes in place, from an already glued piece of film. Moreover, if it is slightly wrinkled during operation, it must be changed. Two sashes are cut between themselves only at the very end of the process. You need to cut with a sharp construction blade.

Use self-adhesive foam tape to ensure there is no gap between the homemade plastic check valve for ventilation and the wall.
During operation, it is necessary to periodically clean or change the plastic mesh, which is clogged with dust.

With proper manufacture, such a home-made plastic check valve for ventilation will last for more than one year. And the residents of the apartment will permanently get rid of the reverse draft, which is typical for the ventilation of apartment buildings.

How to choose a check valve

Naturally, the consumer chooses a non-return valve for ventilation, the price of which corresponds to the quality of the product.

In some models, exhaust fans are provided, in which case the cost of the device will undoubtedly be higher. In addition, the price is influenced by the size of the check valve, the material from which it is made, the type of section, purpose, manufacturer.

On average, the cost of a check valve varies from 300 rubles to 3500.

The effective operation of the check valve depends largely on the speed of the air flow through the ventilation duct. It is necessary that the blades come into motion even from the slightest movement of air, since insufficient draft is the first reason for the inefficient operation of the entire ventilation system, arranged according to a natural principle.

To increase draft, exhaust fans are installed in the ventilation ducts complete with check valves.

Without these devices, the non-return valve will serve as just a damper that blocks air from entering. Fans should also be selected based on the required power, which is calculated based on the volume of the room.

A significant part in the correct operation of the check valve is taken by such factors as the climatic features of a given region - temperature, the prevailing wind direction and its speed. Low temperatures lead to icing of the valve, and the wind contributes to the fastest clogging of the ventilation ducts.

Today, manufacturers claim that a plastic non-return valve for ventilation, whose throughput is 4-6 m / s, is very popular. In addition, it does not create noise, and can be used with exhaust fans, and as an independent device.

The choice can be influenced even by the appearance of the decorative grille, which also, to some extent, performs the function of a check valve, albeit a minimal one.

You can equip your apartment or house with a check valve by buying it and inviting a specialist to install it, but you can also do it yourself. The choice is yours.

The ventilation system is a necessary communication for any building. It consists of a large number of components that provide ventilation of the premises. Among the most important parts of exhaust ventilation, a non-return valve is often distinguished, it eliminates the possibility of turning the air flow in the hood and thanks to it, fresh air always enters the rooms. Let's talk about the design and creation of a valve with your own hands.

Functional purpose - how does a check valve work?

Any problems in the operation of home ventilation quickly become noticeable - unpleasant odors appear in the apartment. This is usually due to reverse draft, in which part of the air from the ventilation duct returns to the living space. There are several reasons for these problems:

improper installation of the exhaust pipe;
insufficient supply air entering the system;
installation in one of the apartments of a multi-storey building of a powerful forced ventilation system, which negatively affects the operation of the general house ventilation system;
check valve failure.

The check valve is a device, the main structural element of which is the shutter. The shutter should open under the action of the air flow in one direction only. If the air currents are not directed from the living quarters, but into the rooms, the shutter closes automatically. By installing a non-return valve for ventilation, you protect your apartment from possible unpleasant odors, from back draft, no matter what it is caused by.

Check valves for ventilation systems are made in the form of a disk or flap. They can have different sizes and cross-sectional configuration, which can be round, rectangular and other types. Such devices may be heated or operate without heating. Heated appliances are suitable only for installation in electrically driven ventilation systems, they are good because they completely eliminate the risk of condensation in the system and ice due to this in the winter season.

The main characteristic of check valves is their throughput. According to current standards, for normal ventilation of an average dwelling, it is necessary to install valves with a capacity of 4 to 6 m / s in the ventilation. On the market you can find such devices made of metal and plastic. Metal devices are more durable and reliable, but during operation they can make loud and unpleasant sounds - pops when the shutter is closed. Another disadvantage of metal products is that when condensation forms, they can rust. Plastic valves, although not as durable, are more popular today. They are completely silent, are less expensive and are not subject to corrosive processes.

The valves not only prevent back draft, but also prevent debris from entering the ventilation - small insects and dust.

Design features of modern devices for the ventilation system

Check valve ventilation is very common today. In terms of functionality, such systems are much better than communications in which the air flow is adjusted manually. Check valves can be found on the market in four different designs. Each type has positive and negative features, which should be remembered when choosing a device for your ventilation system.

The first type of valve is a single leaf gravitational action. The air flow that enters the ventilation system from the premises acts on the valve, opens its shutter and is removed into the exhaust part of the communication. If there is no air movement from the apartment, as well as when the air flows back from the ventilation to the apartment, the flap on the valve will be closed.

This type of valve can be used in natural ventilation systems. When properly installed, the valve will require minimal airflow to open - the resistance of the valve to open is very low. According to the design, such single-leaf devices are of two types. In one of them, the axis on which the shutter is fixed is installed with an offset relative to the middle of the air channel, in the other, a counterweight is installed inside or outside.

Since such devices close under the influence of gravity, they require a perfectly level installation in the system for their normal operation. For installation strictly vertically or horizontally, it is necessary to use a level. Otherwise, the valve may not close tightly, which means that it will not be able to fully protect the interior from back draft.

The second type of protective devices are double-leaf with springs. Such a valve is called a "butterfly" because it has two shutters that fold under high pressure from the side of the apartment and close due to springs when there is no pressure. They are much easier to install than gravity ones - they can be placed in ventilation ducts at any angle.

Butterfly valves can only be used for forced ventilation systems with an extract. Before buying and installing a "butterfly", it is necessary to check the sensitivity of its curtains - the ability to open under air pressure, characteristic of the system in which the device is planned to be mounted. In some modern products, the sensitivity of the flaps and springs can be adjusted.

Another type of product designed to prevent back draft is special blinds installed on the ventilation grille. Blinds work on the gravitational principle, like single-leaf dampers, the difference between them is only in the number and size of the shutters. A large number of small sashes make it possible to install such compact devices in the external elements of the system.

There are blinds on the market in standard sizes, corresponding to the size of the ducts for hoods and openings for natural ventilation. You can find grilles with shutters that are equipped with springs or membranes, however, such design solutions are considered unreliable, the grilles will not function well at low temperatures if they are installed outdoors.

The last common type of check valve is the flexible diaphragm. In this device, a flexible plate is installed, which can be bent under the influence of air flow. When properly installed, the membrane will open the vent in one direction of airflow and close in the opposite direction.

When buying a membrane, you need to take into account the amount of reverse thrust in the ventilation duct. If there is a possibility of deformation of the flexible membrane by air currents, it is necessary to buy membranes with additional stiffening ribs. When installing a conventional membrane in a system with a strong "return", there is a high probability of damage to the valve and the termination of its normal functioning, due to which unpleasant odors and other evidence of improper ventilation will appear in the apartment.

Is it possible to make a valve yourself - learning to save

To create a ventilation system with back draft protection, it is not necessary to buy a valve, you can make it yourself. You still have to buy an exhaust fan in the system, but you will significantly reduce the overall budget. To create a valve you will need:

a piece of textolite or plastic according to the size of the ventilation hole (4-5 mm thick);
a piece of thin plastic or plastic wrap;
self-tapping screws;
fan;
drill;
rubber pads;
glue.

From a piece of plastic, you need to cut out a plate that repeats the size and shape of the hole in the ventilation duct. This will be the base of your valve. Now along the edges of the base you need to drill a few holes. The number of holes is determined individually, they should be enough to be able to fix the panel to the wall and fix the fan. In the center of the plate, also make holes through which exhaust air will be removed from the room. You will have to determine the number of holes yourself, according to your personal needs. The more holes you make in the central part of the plate, the more throughput the valve will have and the more functional it will be.

Now you need to fix the hood to the finished base. First install the rubber gasket at the junction and only then fix the fan. The more hermetic the created device is, the better it will function. You can also put pieces of rubber under the fasteners so that the fan creates a minimum of noise and vibration during operation.

Next, you will need a dense plastic film (at least 0.1 mm thick) or a sheet of thin plastic. Of these, you will make valve flaps. The film or plastic must be cut to the size of the base, and then glued to the prepared plate as a whole. These homemade sashes should completely cover the ventilation holes. Next, you need to cut the sash into two equal parts. The cut should be as even as possible, therefore, for cutting, you need to use really sharp tools, for example, a clerical knife, which is easy to separate the plastic film into two parts.

Install the finished valve into the ventilation duct and securely fasten it with self-tapping screws to the wall. There will definitely be gaps between the wall and the valve, they should be carefully sealed with sealant. This completes the creation of a homemade valve. When performing work according to the instructions, you will get a decent device that is practically not inferior in functionality to products made in an industrial environment. Such a homemade valve can work effectively for 2-3 years.

It will work according to the simplest principle. Under the influence of the air flow from the fan, home-made sashes will open, allowing you to ventilate the interior and remove the exhaust air. In the event of a reverse draft, the film will slam shut and absolutely hermetically close the ventilation hole, that is, unpleasant odors and pollution will not get into your room from the ventilation duct.

Regardless of whether you buy a check valve or make it yourself for the system, this device will significantly increase the functionality of the ventilation system and reliably protect your home from back draft.

December 02, 2019 No comments

Installing a non-return valve is an opportunity to get rid of the exhaust air with unpleasant odors entering the apartment from the ventilation system.

In any multi-storey building there should be ventilation vents. According to the plan, their installation is provided in the bathroom, in the kitchen, in the bathroom. They have a connection with ventilation ducts that run perpendicular from the first floor to the top. All apartments are connected to this system by a riser.

Sometimes an unpleasant smell begins to come from the exhaust ducts into the apartments. Some owners of the premises, who do not understand the essence of the problem, begin to block the ventilation windows either with mechanical valves or with cardboard, tightly attaching them to the wall.

Such a design error is fraught with dangerous consequences. The operation of the hood must not be interrupted! And it does not matter whether the owner of the apartment is currently using the bathroom, toilet, kitchen, or he has temporarily left, or simply does not want to put up with temporary inconveniences.

Channel overlap is followed by:

violation of normal air exchange;
increase in humidity;
presence of stale air in the rooms.

The only way out

There is only one way to solve the problem: it will be necessary to block the movement of air flows coming from outside. At the same time, the introduced system should not interfere with the air masses that filled the room to go outside.

The problem is solved by installing a check valve in the ventilation system.

Common causes of reverse thrust

At first, you will need to understand the nuances of the exhaust ventilation system in an apartment building. Only then will it be possible to understand why air can enter through the vents into the room, and does not exit along this path.

Most often, in modern designs of apartment buildings, exhaust ventilation is installed according to this scheme.

Special instruments - anemometers showing the speed of the discharged air flow

A common exhaust ventilation duct is created in the form:

mines;
ventilation shaft.

Separate "channels-satellites" are being built. They are connected to a common ventilation outlet.

Houses of different series and types are being built. So the trunk is created:

or common for all premises (all apartments are also connected to this system via a riser);
or from two separate sections - for the kitchen and for the bathroom (toilet, bath).

The rules do not provide for the vent to go directly into the barrel. An inclined connection or a vertical section is being constructed (herringbone pattern). As a result, individual channels significantly affect the functionality of each other. And if the appropriate conditions are created, the overflow of air flows into the premises of other floors, unforeseen by the purpose of the structure, will begin to occur.

Then, instead of extracting the exhaust air into the vent, exhausted air masses with unpleasant odors begin to flow into the apartment from the same vent. They come out of a common trunk. A “thrust rollover” is fixed (there is a so-called reverse thrust).

In winter, due to this phenomenon, cold air enters the room. Then not only the general ventilation system is disturbed, but also large funds are spent on heating the stuffy room.

Formation of reverse thrust directly in the system

This problem can be both very serious and temporary.

Reason one. Natural draft is directly dependent on the height difference, which begins with the location of the vent, and ends with the mouth of the ventilation duct. In this case, all other conditions may be ignored if they are ideal. The natural draft on the first floor should be higher than those on the top.

The second reason. The ventilation duct is overgrown with dirt. The air taken out of the apartment (especially from the kitchen) is abundantly saturated with moisture, fumes with the presence of fat. This mixture partially settles on the walls of the mine, then dust sticks to it, which leads to a gradual decrease in the passage cross section.

Reason three. It is temperature that can have a rather serious effect on the level of traction. More precisely, the difference in temperatures recorded at the point of exhaust air intake and in the zone of the mouth of the ventilation duct affects. In winter, traction increases, usually the system runs smoothly.

But in the warm period, unpleasant surprises may occur in the form of reverse thrust due to insufficient air circulation in the channel itself. It is cooler in it than outside, so the air stagnates or even begins to circulate in the opposite direction.

Reason four. At the mouth of the canal in winter, the air is strongly cooled, its density increases significantly. An "air lock" is formed. Then the thrust begins to weaken, it can “tip over”. Air enters the vents of the rooms located on the upper floors. And all the “aromas” that are produced in the apartments of the lower floors enter the rooms on the middle floors.

Reason five. This circumstance applies to old buildings. Their channels were entirely designed for natural ventilation. In the future, residents began to install forced air pumping devices. It is enough to install a kitchen hood in one of the apartments, as the balanced performance of the entire system will be disrupted.

Reason six. The shaft can be checked by installing a mirror (this method of checking from the apartment is not considered optimal in all systems). The passage must be absolutely free. However, the passage of the air flow is sometimes hindered by the resulting blockage. The channel turns out to be partially, and sometimes completely clogged with bulky debris. The reasons may be:

builder's mistakes
imperfections of unfortunate repairmen (they forgot to remove the rag);
destruction of a brick pipe;
the fall of a dead bird, another animal.

Reason seven. Often, external conditions violate the state of traction. For example, a strong wind does not allow air to escape from the system. The reason is that the usual design of the head of the ventilation pipes does not have high-quality deflectors.

In other cases, the cause is the demolition of a building near an apartment building or the construction of a new building, cutting down trees or reaching a certain height. Powerful air currents are formed that affect the free exit of air from the ventilation system.

Causes of reverse thrust caused by problems in the apartment itself

Both apartment owners and owners of private households should pay attention to these reasons.

The "golden rule" of the balance of ventilation flows is violated: in what volume the air enters the room, in the same volume it must be removed through the exhaust duct. If the air flow is minimal (windows are always closed), then ventilation, in principle, cannot work.

You have to install inlet valves. Such systems:

crash right into the windows;
mounted in holes drilled in the walls.

The owners install a vent. ducts, all air outlet points can be connected to them at the same time:

hood over the stove;
kitchen ventilation;
ventilation system in the bathroom;
ventilation system in the bathroom.

Sometimes the predominance of one flow, associated with the connection of forced ventilation, significantly affects all other flows. Then the air intended for removal to the outside begins to flow into the adjacent rooms.

All situations listed above can be positively resolved if a check valve is installed. But this innovation in the system only allows you to get rid of the unpleasant manifestations of reverse thrust. The cause of its occurrence still remains unresolved.

Different types of check valves: principle of operation, device

Both the check valve device and the principle of its operation are not complicated. Due to its simplicity, the system works quite reliably.

A shutter channel is built into the duct, capable of functioning only in one direction. When the air flow is normal, the shutter remains open. As soon as the flow direction is changed, the channel is immediately blocked. Supports automatic operation.

While maintaining the principle of operation, the designs of the valves themselves differ.

A plate (shutter) is installed that completely covers the ventilation duct. It is mounted on an eccentrically located axis. In other words, one of the shutter halves is larger than the other (heavier). This contributes to its return to the closed position (to its original state), if there is no direct air flow through the channel. For this reason, these valves are called gravity operated designs.

For home ventilation systems, plastic options are made. At the same time, the weight of the sash should be insignificant so that it can open even from natural draft in the ventilation duct. Lack of draft or reverse movement of air leads to the closure of the sash.

Double leaf check valve

They are also called "butterflies". They become like a moth when semicircular flaps open from the central axis, like insect wings. Typically, the leaflets of the valve system are equipped with springs to return them to their original state.

When a flow of a certain density is created in the duct, the force of a weak spring is overcome by this flow. Then the sash opens, and this ensures a normal passage. The pressure increases - the valve opens wider.

Multi-leaf check valve

This design is suitable for a system where there is a need to cover a vent having a large cross section. This device differs from all others in that it is installed at the end of a horizontal exhaust duct. For example, at the exit point to the street.

How to make and install a check valve yourself

Step one. The ventilation grill is removed, screwed with self-tapping screws.

Step two. The basis for the valve is formed by a cardboard frame. It won't be hard to cut it out. Its dimensions must correspond to the size and shape of the ventilation grille, because it will be located behind this grille.

To do this, lay the grate on a piece of cardboard and outline the dimensions around the perimeter. A rectangle is cut out (usually the exit to the channel has this shape). If necessary, then an additional adjustment is made: the cardboard fragment must exactly match the shape of the lattice along the outer border.

Step three. The cardboard base of the valve is marked. At first, the contour of the vent is outlined on the cardboard (horizontally and vertically, the indents from the edges should be the same). Next, the valve windows are outlined.

From the border you need to retreat to the center of 10 mm and draw 2 rectangles. They will become the windows of the valves. These indents will be required:

First of all, to allow the edges of the membranes to block the flow of reverse thrust when they are pressed against the cardboard;

Secondly, so that the membranes, when opened, cannot touch the walls of the vent;

third, for attaching membranes.

Step four. In the center are two rectangular windows. Between them should leave a strip - 15 mm wide. The elastic membranes will converge on it when the valves close.

Marking lines are applied. Two windows are cut out along them, and symmetrically. Air flow will flow through them. Two elastic petals are cut out of the film, which will serve as membranes. These petals are attached with reliable glue to the cardboard base (along its outer edges).

Step five. The function of the valve is checked. It is attached to the ventilation outlet in the position in which it will remain permanently. For temporary fastening, self-tapping screws are used, inserted into the dowel-plugs, designed to permanently fix the grating.

Something can interfere with the free movement of the membranes, then these minor shortcomings are eliminated. The operation of the valve should be checked with the window open to activate air flows and increase traction through the tested vent.

Step six. Only after making sure that the device really works, you can start installing the plastic decorative grille in its original place.

Video: Do-it-yourself check valve for ventilation. Easy and cheap:

What is the essence of the ventilation system in the room? Its main task is to eliminate unpleasant odors, moist air, smoke and steam from cooking, and replace it with a clean one. In old houses, natural ventilation used to prevail, but the fashion for metal-plastic windows, stretch ceilings and plasterboard walls reduced its effectiveness to nothing.

Exhaust fan with non-return valve provides full air circulation

Without an additional ventilation system, in such conditions, damp corners with mold colonies appear, always misted windows. Smoke, odors and steam remain in the room, and there is no full air circulation. In this case, it is necessary to attend to the device of an exhaust fan with a check valve.

The principle of operation of the check valve

There are fans with a check valve, duct, supply, exhaust. All of them are used to smoothly replace the stale air in the room with fresh air. The main difference between any ventilation and air conditioning is that the latter work with already existing air masses. Hoods, on the other hand, guarantee the replacement of air with fluff, bacteria, midges and various allergens with fresh air if a supply and exhaust valve is installed on the fan.

This type of exhaust fan is very popular among residents of apartment buildings and private houses. This type of hood is used:

for bathroom and toilet;
in kitchens;
in the steam room;
in smoking rooms;
in cellars and cellars;
in laundries;
in offices and shops;
in sanitary compartments, etc.

The hood with a valve has a fairly simple device, but the principle of its operation is rarely described. Despite this, the buyer needs to know that they are divided into three types:

spring or self-closing;
controlled by electricity or manually;
passive - the lid closes and opens under the influence of air flows (direct and reverse).

For an illustrative example, let's analyze a spring or gravity household fan installed in a bathroom, kitchen or steam room. While the motor is running, the lid is in the open position. When there is no need for ventilation, the blades of the device stop and the cover slams shut under the influence of a spring. Do not expect absolute sealing from it, but it prevents the ingress of odors from the ventilation shaft (especially important for houses with garbage bins).

Exhaust system with non-return valve suitable for large offices

An electrically controlled hood with a non-return valve is used primarily for organizing an automated exhaust system. This type is suitable for workshops, warehouses, factory premises, shopping centers and large offices. Such ventilation prevents the appearance of mold, moisture, condensation, mustiness on the walls and objects inside.

Passive ventilation systems are the least popular. They can be used for kitchen hoods, but quite rarely.

It is worth mentioning that the anti-return valve for the hood can be heated (prevents the accumulation of condensate and the formation of frost on the lid in winter) and without heating. The first option is more appropriate to install if the fan goes outside. The second option is suitable exclusively for indoor installation (apartment building).

Choosing a fan for your home

Exhaust fans for bathrooms and toilets, kitchens and cellars are sold in different sizes and modifications, with blades of different shapes. Some have an inertial grill that, like shutters, closes as soon as the engine shuts down. Economical models with a built-in timer are also sold. It allows you to set the operating time of the device.

When choosing, it is recommended to pay attention to the ability to adjust the power of the hood and manually turn off the power. A steam room, a small-sized shower room, a bathroom with a jacuzzi - for such premises, experts advise choosing models with a humidity controller. The fan turns on automatically if the steam level in the room reaches the mark set in the device.

If you have decided on the ventilation configuration, it is important to consider three factors directly when buying:

the area of the ventilated room;
type of room (performance depends on it);
the number of people living in the house.

The device must have sufficient power to meet all the requirements of the ventilated room.

Exhaust fan for kitchen

Do you need a non-return valve for a kitchen hood? On the hob, the magic of cooking happens every day: something is fried, boiled, stewed, baked, jams and pickles are rolled up. In the process of creating another culinary masterpiece, fat, steam, soot and smoke rise to the ceiling. All this remains on the walls, curtains, whitewash, and the natural ventilation grate, which has not been working for a long time, is gradually overgrown with “moss”. To avoid frank damage to your own property, get rid of excess odors and moisture, you need to install a hood in the kitchen with an anti-return valve.

The easiest way is to put it above the stove in the opening of the mine for natural ventilation. If the windows are old, with a wooden frame, you can install the fan directly into the window. If work is carried out in a private house, the output is street, through the wall.

An important parameter for a kitchen hood (as for any other) was and is performance. That is, the volume of air processed in one hour. To choose the right device, you need to calculate the cubic capacity of the kitchen: the height of the ceilings multiplied by the area. According to sanitary standards, the air exchange rate (the number of cycles of complete air renewal) is set for each room. For the kitchen, this figure is 8-12. For multi-family buildings, it is also necessary to take into account the minimum safety factor (compensation for losses during venting due to a number of problems with shafts). The average coefficient is 1.3. To get the performance of a fan with a check valve or just a kitchen hood, we multiply the cubic capacity, the air exchange rate and the mentioned coefficient.

Anti-return valve prevents dirty and cold air from entering

Important! The anti-return valve in the ventilation does not allow cold or dirty air to enter the room, but only removes the exhaust from it. With the ventilation turned on, it is important to create an air flow into the kitchen.

The second important point is the noise level. It is measured in decibels. The noise is created by a running fan motor that drives the blades. The device is better, the less noise it produces.

And don't forget power. The higher the indicator, the better the intake of exhaust air, and the anti-return valve will not allow "aromas" to return to the kitchen. But it should be understood that a powerful fan costs an order of magnitude more expensive, sometimes compared in price with a middle-class hood.

Do-it-yourself ventilation with a valve

Are you looking for check valve bathroom fans, but the price is too high for you? Do not despair, because the design of the device is not so complicated. If you study the principle of operation in advance and make a little effort, you can make a full-fledged non-return valve for ventilation with your own hands.

More often, an axial anti-return valve is installed on the fans. It can be in the form of a "butterfly", a square cover or a round flap disc, a grille of blinds. The sizes for household hoods vary from 100 to 315 mm. But not everyone can do this with their own hands. We will consider a simpler option.

To make a fan with a check valve, you must:

a piece of textolite or dense plastic with a thickness of not more than 4 mm;
ideally smooth dense polyethylene with a thickness of 0.1 mm;
rubber pads;
self-adhesive thin foam;
self-tapping screws and bolts;
stationery knife;
adhesive tape on a fabric basis.

To create ventilation with a valve, fabric-based adhesive tape is required

Let's get to work:

A plate is cut out of plastic. The required size slightly overlaps the outlet of the natural exhaust channel. Holes are drilled at the corners of the plate for fastening to the wall.
In the center of the plate, a hole is marked corresponding to the diameter of the fan. It should be with a grid (the larger the cells, the denser the shield material). Cut out an opening with a grate for air intake.
Around the finished air intake, you need to make 4 holes for fasteners, with which your workpiece will connect to the fan.
To prevent small debris and insects from entering the apartment or house through ventilation, a fine mesh or nylon is pulled over the grate. The latter is easy to replace if necessary.
We connect the base with the fan using bolts and shock absorbers, having previously laid a rubber gasket between the elements. This will prevent the "walk" of the air.
Impeccably smooth polyethylene is glued to the base with adhesive tape and only then cut out. You need to use a sharp clerical knife. Check the condition of the film. If the slightest waviness or folds appear, it should be replaced. An uneven surface leads to depressurization of the valve and reverse draft from the ventilation shaft to the room.
When the canvas of the valves is cut, it is cut in half. This must be done at the very end so that the film remains intact and immovable for as long as possible.
When installing a homemade fan with a non-return valve in a steam room, in a kitchen or in a bathroom, be sure to lay self-adhesive foam rubber between the wall and the plastic shield to better seal the device.

Your fan with an anti-return valve should be periodically cleaned and the plastic mesh changed, especially if it is installed in a steam room. In this case, it will last for many years, and you will save on the purchase.

Now you know how to protect your home from dampness, soot, unpleasant odors inside and out. Install a household exhaust fan with a non-return valve in the kitchen, in the toilet, in the steam room, in the office or in the store and you will be provided with clean air.

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