Ventilation check valve without fan. How to choose and install a check valve for ventilation

A non-return valve for ventilation in an 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 often residents make it with their own hands. The installation process is simple and will not take much time.

In this article, we will consider information about why a check valve is used in ventilation, its purpose, types and installation by specialists or by our own hands. After installing such a device, you can forget about any extraneous odors in your apartment.

What is a check valve for?

A 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.

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

Absence - it can be broken or clogged, and therefore 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 during the operation of the stove, the combustion draft increases in the chimney, which contributes to the return 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 air flow in other apartments is disrupted.
The presence of several hoods in one apartment will increase traction in one of them, which will lead to a violation of the outflow of air.

You can use a candle to check for draft in ventilation. Bring the lighted candle in the ventilation and open the window. If the air flow is correct, then the candle will go 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 rear, and it is attached to the fan axis.

The valve is specially designed not to allow 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 decrease or increase the size of the section of the ventilation duct. Depending on the task of the non-return valve, there is a greater or lesser inflow of fresh air or an outflow of contaminated 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 the ventilation ducts, their poor tightness.

by material of manufacture;
by form;
by 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 offered 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, therefore 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, practically without human intervention, using microcircuits.

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

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

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

It is easy to guess that we are not talking about natural ventilation, but only about a mechanical, forced type. Although the damper is designed so that it opens and closes easily, the natural flow of air is unable to lift it. Is that 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 grilles - is the need for forced ventilation. As a rule, such structures are most often installed at the outlet of a ventilation shaft under a conventional kitchen hood.

flange for connecting the air duct;
fixed part (lattice);
movable part (flap-valve).

The section in which such structures are presented is usually rectangular, but there are also round options. The air outlet flange is always circular. 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 mechanical impact of something).

The damper itself is presented in the form of a rectangular or round petal that opens in one direction. The connection to the main body is flexible 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 vent grille is made is plastic. Since the structure is often located in an area of high humidity, the use of metal moving and stationary parts is not recommended.

However, in everyday life you can find homemade galvanized steel gratings. 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 axle, and contain the principle of operation of the rotary mechanism. With the flow of air masses, this damper 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 flaps open and begin their work. This type is installed in 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 grill, thereby preventing air from entering.
Butterfly. Similar in structure to the petal-type 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, valves are of horizontal and vertical type, with or without heating, as well as rectangular or round.

Fans with a non-return valve are divided into axial and centrifugal types. Their main characteristics, which you need to pay attention to when selecting, 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. Check valves they have are plastic, metal or thin film; they also differ in place of installation 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 rooms.
Waterproof design.
The body 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 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 switch-off delay.

Thus, before you are going to buy a fan for a bathroom with a check valve, find out well how the model works, whether it has sufficient performance for your room, what is the 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 small 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. The installation location is not determined correctly. Before starting the fastening, it is important to carry out some calculations, take into account the height of the ceiling, the width of the walls, etc. 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 touch 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 exclude 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 with 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 peculiarities of your house, its location, and installation of the fan.

In order to exclude all mistakes that an 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.

A bathroom is a room with an elevated one. Natural ventilation for a given room, in most cases, is not enough. An extractor hood with a check valve in the bathroom will help to improve air exchange. An axial or duct (radial) fan is most often used as a forced draft device.

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

Usually, 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 minimum aerodynamic resistance.

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

Constant ventilation mode. Such models work constantly. They are equipped with a humidity sensor. Depending on the readings, the speed of rotation of the blades changes. Despite the continuous operation, such exhaust devices are quite economical.
Sleep timer. Saves time and energy. Such devices do not require shutdown. After a specified period of time, the fan stops working on its own.
Motion Sensor. Analogue of a timer. Only with this function, you do not even need 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 proof. A useful feature for the bathroom. Especially if the vent is located above a bathtub or shower. The minimum protection level of the device must be at least IP5.

We should also dwell on the check valve.

The ingress of exhaust air masses from the ventilation shaft into the room.
With a complex ventilation duct system, the valve will help regulate the direction and speed of the air flow.
In private houses, the presence of a valve will help reduce heat loss, preventing cold outside air from entering the room.

The widespread use of hoods for the bathroom with a non-return valve, made by a single design. This is very convenient, since the valve installed on the hood is ideally matched in size, material and method of opening to a specific hood model.

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

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

First, you have to dismantle the fan that you have successfully used. We install the check valve body into the ventilation hole and make marks at the places of the proposed fasteners. The body is to be removed, and you need to drill holes on the marks obtained.

We return the case to its original place and through the resulting holes we put 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 will definitely not be able to use a puncher, so you have to use a bolt (a device for mechanically making holes in concrete bases).

We drive dowels of the appropriate size into the holes. It remains only to put the check valve back in place and screw all the fasteners all the way. 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 it is necessary to supplement the installation of the check valve with sealing. The simplest thing is to silicone all the gaps.

Note! This moment cannot be ignored in any way, since the air draft will be insufficient to overlap the valve curtains. This will not damage the ventilation, but the valve will either not perform its main function, or will not fully.

After completing all the described work, you have to install the fan in its original place. On this, the mission can be considered completed: the ventilation will work reliably, the check valve will not let foreign odors into your home.

Currently, check valves began to appear on the market, which do not imply such drastic changes. Such devices are not mounted behind the fan, but directly in front of it. Such kind of valves are overhead.

They work no worse than those described earlier. The only peculiarity is that the valve will protrude somewhat above the plane of the wall. With a good case design, this can be the simplest solution to ventilation problems, and will give this device a peculiar 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 is no universal size for ventilation shafts, so it was decided to provide the entire market with goods in all directions to the maximum.

There are check valves designed for different sections of ventilation wells. Square check valves are especially reliable. Their peculiarity is that they are not afraid of various kinds of distortions and are very easy to install in wells of any section. Such devices can reliably provide ventilation in any home.

Is it mandatory to buy a ready-made check valve? You have to decide this question yourself. As you may have guessed, almost any man can make such a check valve.

It makes no sense to make more complex structures 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 gap for valves is quite significant. The simplest designs are ten times cheaper than more complex counterparts.

By the way, expensive check valves do not go to retail, as they are sold complete with fans.

The point is big: the design of the valve is designed 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.

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

For the base of the check valve for kitchen ventilation, thick plastic or textolite is suitable. You will need a plate overlapping the outlet of the exhaust duct and no more than 4 mm thick. Markings are made on the plate: a grill the size of a fan hole, as well as holes for fastening to the wall (in the corners) and for attaching the fan.

The larger the mesh of the lattice, the denser the material for the sashes should be!

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

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

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

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

To avoid a gap between the homemade plastic ventilation check valve and the wall, use self-adhesive foam tape.
During operation, it is necessary to periodically clean or change the plastic mesh clogged with dust.

When properly manufactured, such a homemade plastic check valve for ventilation will last for more than one year. And the tenants of the apartment will get rid of the back draft typical for the ventilation of apartment buildings for a long time.

How to choose a check valve

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

Some models are equipped with exhaust fans, 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 efficient operation of the check valve depends largely on the speed of the air flow through the ventilation duct. It is necessary that the blades set in motion even from the slightest movement of air, since insufficient thrust is the first reason for the ineffective operation of the entire ventilation system, arranged according to a natural principle.

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

Without the presence of these devices, the check valve will serve as just a damper that blocks air access. Fans should also be selected based on the required power, which is calculated based on the volume of the room.

Factors such as the climatic features of a given region - temperature, prevailing wind direction and its speed - take a significant part in the correct operation of the check valve. The low temperature leads to icing of the valve, and the wind contributes to the quickest clogging of the ventilation ducts.

Today, manufacturers claim that a plastic check valve for ventilation is very popular, with a throughput of 4-6 m / s. In addition, it does not create noise, and can be used when exhaust fans are operating, 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 purchasing it and inviting a specialist for installation, but you can do it yourself. The choice is yours.

Residents of apartments in multi-storey buildings are often faced with the fact that smells from neighbors through ventilation ducts enter their premises. An unpleasant situation that the ventilation check valve will help to cope with. How it looks, how it is arranged and where to put it, and we will discuss it.

What is a check valve for ventilation

During normal operation of the exhaust ventilation, air moves from the room to the outside. Exhaust openings are located "in dirty or wet" rooms - a bathroom, a kitchen. The task of this part of the ventilation system is to bring odors and excess moisture out into the street. But sometimes a situation arises when through the exhaust ventilation the air goes in the opposite direction - it enters the premises. This moment is called overturning of the thrust and they try to fight this phenomenon.

Why fight back thrust? In the case of apartments, this is fraught with odors from neighbors, which is very unpleasant. If we consider private houses, portions of outside air in them reduce the temperature in winter. The second moment is more dangerous and unpleasant - during reverse draft, the boiler can go out, combustion products (and carbon monoxide too) can return to the room from the chimney. In any case, the reverse movement of the air flow is an incorrect operation of the ventilation system and this phenomenon must be combated. A check valve for ventilation is just installed to block the movement of air in the wrong direction.

Device and principle of operation

A check valve for ventilation is most often a piece of pipe with a round or square cross section. In this segment, a piece of material (metal, plastic, mica) of a suitable shape is movably - usually on an axis - mounted. This is the valve itself. In the closed state, it completely overlaps the cross-section of the pipe; in the open state, it should create as little resistance as possible. For everything to work correctly, you need to set it so that when a reverse air flow occurs, the valve closes.

Not only valves are placed in the pipe for ventilation - there are options for a ventilation grill and a fan. In the case of a ventilation grill, a thin plastic or mica membrane can be used that is attached to the grill. There is also a butterfly valve and louver-type strips. The return air valve on the exhaust fan can be of the same type.

The principle of operation of this device is simple: during normal air movement, the valve is open and creates little resistance to the air flow. In the event of a reverse draft, it closes, preventing the ingress of foreign odors or cold air from the street into the room.

Troubles that may arise

Everything seems to be clear and logical: odors in the apartment are very unpleasant. Rollover traction in a private house is no less unpleasant, but also dangerous. In principle, with a correctly calculated system, such phenomena should not arise and the causes of their occurrence should be fought. But not everyone has the capabilities and resources. It is easier to install a non-return valve for ventilation. This is true, but there are nuances worth knowing.

As you can see, putting a check valve on ventilation does not mean solving the problem once and for all. You will have to monitor the state of the system and put up with the shortcomings of this solution.

Kinds

The ventilation check valve can be made of metal or plastic. Metal is most often galvanized steel, less often stainless steel. There is also a small group with a plastic casing and a metal damper - most often called the "combined check valve for ventilation".

How to choose on this basis? Just. Choose the material from which your duct is made. Models can be round or square. Here again we choose the same form as for the existing / planned ones. Fortunately, the dimensions correspond to the standard pipes used for air ducts.

Opening method

Check valves can be opened in different ways:

Manual... The dampers are opened or closed manually, for this they have a special lever. This is not very convenient, in addition, due to the design features, they do not differ in tightness, so that they cannot completely block the penetration of extraneous odors.
With electric drive... They are forced to open at the same time as the fan or hood is turned on. Suitable only for ventilation systems with forced air removal (no natural circulation).
Mechanical... The most common type. They open and close against air movements. They are installed both in tandem with a fan or an exhaust hood, and for natural ventilation.

The manual check valve can be installed on a forced-draft chimney to the outside. This is sometimes done - they do not lead to the ventilation duct, but to the street through the wall. In this case, it is better to have a damper that will only open while the hood is in operation. You can, of course, put a normally closed valve, but in cold weather it will freeze and stop performing its functions. Therefore, manual opening is safer in this case.

The most common are mechanical check valves. They are installed in about 90% of cases. Structurally, they can be of different types. Let's talk about them in more detail.

Mechanical valve shapes

Different dampers can be installed in the check valve. The force at which it will move away largely depends on the shape of the damper. If the valve is to be operated with a fan or an exhaust hood, it is important that the weakest fan operating mode can open the damper. They say that the fan is supposed to push the valve. If you want to maintain natural ventilation, it is necessary that the damper can "work" even from a slight movement of air.

The designs and shapes of mechanical check valves for ventilation ducts can be as follows:

It is really not easy to choose a valve for ventilation. If you are guided by what the majority uses, you will have to stop at the cracker. For all its shortcomings, it works more reliably, it opens even with natural ventilation. The most effective way to make the cracker quieter is to take silicone sealant and apply it to the stop ring on the body (do not apply to the disc, as it will become heavier, which means it will be more difficult to rotate). Lubricate the valve disc with soapy water and press it against the sealant ring - until polymerization begins. Then we move the valve, we get an O-ring that extinguishes pops. The result is an almost soundless closing, and almost hermetically sealed.

Ventilation valve: where and how to put

If made without the use of fans and hoods with motors, it is called natural. For everything to work, valves are installed immediately at the outlet of the channels to overlap the reverse thrust. To maintain normal circulation, it is advisable not to use grids that overlap the valve. Yes, this option looks better, but ventilation suffers at the same time. Most likely, it simply will not work with low traction.

If you still want to install in front of the valve, you will have to put up with poor ventilation, slower removal of odors and excess moisture. Only the installation of a grille / valve with a larger diameter than calculated can help. In this case, air exchange will not be affected.

In the case of forced ventilation, the non-return valve can be placed either in front of or after the fan. This choice depends on the type of system and fan. Since ducted models of fans in private systems are rarely used, it usually turns out that the damper is located after the fan in the pipe. How far away doesn't matter. The main criterion for choosing an installation site is ease of maintenance, since the damper will have to be periodically cleaned and checked.

Installation in a kitchen with a cooker hood

When installing a forced draft hood in the kitchen, many people want to preserve natural ventilation. To do this, you need to install a tee at the entrance to the ventilation duct. Connect a hood with a check valve to one of its inputs, and put only a check valve in the second. As you can see, the system is not too complicated, but it works.

How to connect an extractor hood so that natural ventilation remains

Why should there also be a check valve on the hood? Because if it is not there, the return air flow can pass through the hood. Yes, it will not happen every time, but with a strong flow it will.

When installing this unit, try to make sure that the ventilation check valve is located as high as possible under the ceiling. As a result, the warmest and wettest part of the air will be removed, which is very important for the kitchen.

For bathroom and toilet

The ventilation of the bathroom can have its own exhaust duct - then everything is easy, simple and understandable. Before entering the ventilation duct, we put a check valve to shut off the air flow that will move into the room. But not all apartments can boast of individual bathroom and toilet shafts. In some houses with an older layout, there is only an exhaust duct in the toilet. Ventilation of the bathroom is done by passing the box through the wall. In this case, we put a check valve for ventilation not only at the outlet to the ventilation duct, but also in the channel between the bathroom and the toilet. This will prevent unpleasant odors from entering the bathroom.

There is an even more sad situation: when there is only one exhaust duct and it is in the kitchen. Actually, the logic of the installation does not change - it is necessary to place the devices so that smells from one room do not get into another.

One check valve for ventilation is placed on the outlet to the dome hood (or on the channel that removes air from the kitchen), the second on the pipe that goes from the bathroom. As you can see, if you understand the logic of the work, you can determine the most successful installation place yourself.

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To prevent air from moving in the wrong direction, a special device is used. A check valve for ventilation is installed in forced and natural systems. You can buy it in the store, or create it yourself. If necessary, installation is not difficult to carry out without assistance. This article will help to solve the indicated tasks quickly, correctly and inexpensively.

Even such a light barrier is sufficient to prevent air from entering the room from the ventilation duct.

What is a check valve for ventilation: problems and solutions

Signs of a malfunction of the system are foreign odors coming from other rooms (apartments in a multi-storey building). Penetration of cold air in winter disturbs comfort and increases heating costs. Together with the return flow, various impurities penetrate into the room. Some of them can be harmful to health.

It is clear that it is better to eliminate such shortcomings. But first you need to figure out the reasons for their appearance. Some - can be eliminated in order to improve the functional state of ventilation.

Sometimes problems arise after replacing old frames and installing double-glazed windows. New window blocks provide perfect tightness, completely blocking the access of fresh air to the room.

As a rule, filters are installed in these products, which can become clogged over time. Regular inspection and cleaning will help restore the lost functionality in full.

A change in the direction of the air flow can occur when several sampling points are connected to the same duct. Similar manifestations are not excluded in strong winds, in frosty weather. It is especially difficult and even impossible to influence the actions of neighbors in an apartment building. Claims to them can be made only if the air duct is completely blocked. If smells come from someone else's kitchen, where a powerful hood works, the problem will have to be solved independently.

Related article:

In our review, you will find out what the valve is for, the principle of its operation, the device, the advantages and disadvantages, an overview of ready-made models, self-production, features of the installation of the air duct.

The device and principles of operation of the check valve for ventilation

This industrial ventilation air valve functions as follows:

As the air flows in the direction indicated by the arrow, the flap (1) opens slightly.
It is fixed on a metal axle (3) installed in the holes in the body (2).
Under the action of the force created by the load (5), the disc returns to its original position. Using the screw (6), this part can be positioned in the desired place of the auxiliary rod (7) to change the sensitivity of the device.
In the lower position, the disc rests on the retainer (4).

Using this ventilation check valve as an example, individual shortcomings can be noted in order to more accurately formulate the requirements for the parameters of high-quality equipment:

There is an adjusting mechanism here. But it is not intended for installation in residential ventilation ducts hidden inside building structures.
There are no bearings in the center axle mount. It is possible that during the operation of this ventilation check valve, extraneous noise will appear. They will be difficult to remove with lubrication, even if the appropriate procedure is performed regularly.
There are no seals here, so it will not be possible to completely block the air flow in the opposite direction. If technological gaps are not left, the risk of damper seizure increases.

This product is made of sheet steel, which increases strength (not needed in this case), increases weight. Conventional paint does not meet modern requirements for good corrosion protection. The listed facts must be taken into account when creating a design with your own hands, in the course of choosing a suitable model in the retail network.

Different types of check valves

In this article, the scope of the study is limited to household models. These products do not need to be connected to power supplies. Their installation will not cause difficulties for an ordinary user.

Membrane construction: simple and cheap

The principle of operation of a diaphragm check valve is not difficult to understand by studying this photo. The working opening is covered with a flexible plastic film that adheres tightly to the base in the corresponding direction of flow. Choose a flexible but strong enough material. Having chosen the right stiffness, it is possible to set the required sensitivity level. Such an overlay can be fitted to an existing system (fan, grill). There are no mechanical parts and complex mechanisms, which implies reliability and durability.

This "butterfly" does not fly, but performs its functions flawlessly in any position.

In this version, the main functions are performed by the petals fixed on the central axis. They are pressed down by springs, so a significant force is required to open the channel. Such products are installed in forced ventilation systems. Some models are equipped with special devices for adjusting the springs (increasing / decreasing the force of action).

This modification is made of galvanized steel. It is resistant to corrosion processes and weighs a little. A soft damper is fixed on the surface of one plate, which prevents strong shocks and noises.

Features of petal valves

The simple design of the petal check valve for ventilation is one of the main advantages of this product category. The sash is pulled down by gravity. Its relatively low weight does not create much resistance to air flow, therefore installation in natural ventilation systems is permissible.

For your information! It should be noted that this model should be installed only in a horizontal channel. For vertical lines, products with springs (counterweights) are used, which provide a forced return of the damper to its original state.

Check valve application in the kitchen

In this installation with a non-return valve, ventilation is continuous. If you turn on the desired fan speed, the debris removal speed will be increased. Of course, one must not forget about creating an adequate supply of fresh air.

For your information! To increase the efficiency of the system, the length of the channel is reduced, and the exit to the street is made directly in the wall of the room. In this case, it is equipped with an additional valve that blocks the flow of air from the outside along this path.

Important! When choosing a suitable product, you should pay attention to models that are easy to clean, resistant to fats and other specific dirt.

Correct use of the valve in sanitary facilities

For installation in these rooms, structures are used that are resistant to high humidity. We must not forget that powerful agents are used to remove calcium and other persistent formations. The acids and other aggressive chemical compounds they contain are released into the air. They can damage decorative and protective layers, metal parts, welded joints.

Ventilation devices equipped with a non-return valve

This section of the article discusses various combined products. They perform their functions in conjunction with a valve that prevents air back movement. In some cases, they are equipped with production models to improve the original consumer characteristics.

Exhaust fan design with check valve

The petals are pressed by built-in springs. The parameters of these return mechanisms are calculated at the design stage. They correspond to the performance of the equipment (force of the air flow). If it becomes necessary to replace a broken part, a new spring is selected with the same characteristics. This design, with a large number of plastic elements, is well suited for bathrooms. However, it is useful to check the manufacturer's recommendations, the protection class of the electrical device, taking into account the high humidity in the room.

For your information! Mounting the fan on a hood with a spring-type check valve is permissible in horizontal and vertical positions. This universal drive retains the same functionality in any position, at different angles of inclination.

Ventilation grill with a non-return valve: affordable cost - excellent result

This ventilation grill with a non-return valve contains several leaf elements. This solution is used when overlapping large channels. Single parts that are too large are heavy, which does not allow the sensitivity to be reduced to a level that meets the requirements for natural drawing. But when choosing such a model, it is necessary to clarify the tightness of the joints in the closed position of numerous valves.

The principle of operation of the tee with a check valve

The use of a tee for the exhaust hood with a check valve prevents the flow of air from the duct into the kitchen. Another device performs similar functions. It can be installed differently from the picture, but in combination with a fan.

Advantages of a check valve on the hood

Installing an exhaust check valve prevents various contaminants from entering the engine from the ventilation duct. This extends the service life of the equipment.

For your information! Some users fear that the spring actuator and the weight of the dampers will reduce the performance of the venting system. This is not true. These loads are insignificant in comparison with the power of the fans, which are equipped with modern equipment of this class.

If there is no such device in the set from the manufacturer, you can install the anti-return valve for the hood yourself. What it is is not difficult to understand from the materials of the article. Below are instructions for self-creation of functional products and features of installation operations.

DIY check valve process

Photo	Step-by-step algorithm of actions with comments
	The author of the project is going to install a homemade check valve in a 125 mm wide channel under a standard plastic grate. Installation of a forced fan is not planned. It was decided to use the materials at hand to save money. The need for modernization arose due to the flow of unpleasant odors from neighboring premises located on other floors of the building.
	This cover can be removed easily. It is attached to strips of adhesive tape (with two adhesive sides). Over time, they ceased to fulfill their functions, so more reliable means will be used for a new commit.
	After removing the tape and dirt, a good basis was obtained for creating the necessary structure.
	For the valve frame, cardboard, thin plywood, a sheet of plastic are suitable. In this case, an empty packaging from writing paper is used. The corrugated lid has the required strength. An added benefit is that damping sound vibrations is not useful here. But it can be used when creating a design with a fan.
	In order not to damage the workpiece, use a soft pad.
	The contour of the lattice is outlined with a pencil, a rectangle is cut out of the lid along the marked lines.
	Next, measure the width and height of the ventilation opening. It turned out 125 x 170 mm.
	Using a ruler and a pencil, draw the part in the center of the rectangle. Distances from opposite edges to its perimeter should be the same.
	In the central part, a vertical jumper with a width of 10-15 mm is set aside. It will come in handy for attaching the valve, which can be made from a suitable piece of thick plastic wrap. The author used the top of a standard stationery folder (binder).
	The central parts are cut out first.
	Next, the valve flaps are created. They should converge when closed in the middle of the center bar. If a less rigid plastic is used, an additional support bar is installed horizontally in each hole.
	The valves are attached to the side parts of the frame using tape. Check the strength of the fasteners and the functioning of the mechanism.
	The colored surface of the box will be visible through the slots.
	To eliminate this drawback, the workpiece is pasted over with white paper.
	With the help of a practical experiment, you can check the functionality of the check valve for ventilation with your own hands. It is necessary to make sure that the petals move unhindered, reliably block the air flow when closed.
	To increase the test duration, the valve is mounted on self-tapping screws, without screwing them completely. The hole locations are marked in accordance with the lattice parameters. If everything is in order, it is installed on top, attached with screws to the wall along with the valve.

Reverse thrust occurs quite often and has negative consequences. Check valve installation for natural ventilation solves this issue. But for this you need to study the design features of such devices, their advantages and disadvantages, the basic rules for installation and placement in exhaust structures.

The main factors of the appearance of reverse thrust

Operating principle ventilation of the supply and exhaust type is based on the operation of the law of the same volume of air entering and leaving the room. Consequently, in the hood, reverse thrust appears if the total air flow at other points is directed from the apartment. There are major factors for the appearance similar phenomenon:

Connection of powerful hoods by neighbors in apartment buildings, when using common ventilation shafts to eliminate air. This problem is very common in older residential buildings where the shared ducts are not designed for forced ventilation.
The presence of an air duct inside the house, having several points of air intake. In this case, changes in the direction of flow are possible when a forced ventilation device is started in one of them.
Drastic increase in flow volume which exits through one of the available exhaust devices. In case of insufficient air supply by means of supply ventilation, a change in the direction of the air flow in the hoods occurs.
Significant reduction or suspension of the flow, which enters the dwelling through supply ventilation. This happens in the case of gradual contamination of the holes, and in the presence of a forced system - in case of damage or wear of the parts that are responsible for the movement of air.

Ventilation check valve installation for natural ventilation during installation of the system is a rational solution, even if at the moment there are no conditions for the appearance of reverse draft. The price of ready-made systems is not high, but installing a valve in already functioning air ducts is not an easy and time-consuming job.

Check valve types

Today, the use of manual control for air flow control is no longer relevant. For automatic warning unwanted draft in the ventilation system there are several fundamentally different ways. Each of them has its own advantages and disadvantages that you need to pay attention to when buying equipment.

Single-leaf gravitational action

The air flow leaving the room is able to exert pressure on the damper blade, thereby slightly opening it for free air outlet. In the absence of movement or the appearance of reverse thrust this pressure on the damper does not occur and it closes under the influence of gravity.

If the installation was done according to all the rules, the reverse gravity valve is permissible to use with natural ventilation, since it has minimal resistance to opening the sash. There are two options a similar setup:

using a counterweight, which is located outside or inside the device;
deviation of the positioning of the axis on which the sash is attached with respect to the middle of the section of the duct channel.

Note! The sash closure is based on the action of gravity, and therefore the device should be placed using a level strictly in a vertical or horizontal position, which depends on the specific model. Otherwise, incomplete valve closing or an increased air flow in the ventilation system will be required to open the sash.

Bivalve with springs

This is the so-called "butterfly" device, equipped with 2 curtains... With excess pressure, they fold on a certain side, and in the absence of pressure, they are closed by the springs. Since the operation of the mechanism does not depend on the force of gravity, such a device can be positioned at different angles.

This option has proven itself well in the case of forced ventilation using a hood. Before buying a valve, it is worth testing the degree of sensitivity of the curtains to the pressure in the air duct on which the installation will be carried out. The force of the springs in modern devices of this type can be adjusted.

Grille with non-return valve for natural ventilation

In appearance, the grille with a non-return valve for natural ventilation is very similar to window blinds. For such a device, the principle of operation is similar single-leaf version - gravity. The use of several doors instead of one is due to the compactness of the mechanism in the open position, which is quite important for the external components of the ventilation system.

Dimensions of ventilation grilles with a non-return valve for natural ventilation designed for standard hood ducts. As for the device for preventing unwanted draft, it is permissible to place it both on the entire grill and only on the opening for natural ventilation.

Using a flexible membrane

The working principle of the diaphragm check valve is based on the ability of the flow to change the position of the flexible plate. It allows in the case of one direction air flow, open the ventilation hole, and if the opposite is true, close it, closely adjoining the perimeter.

If there is a risk of changing the membrane due to powerful reverse thrust, it is necessary to have auxiliary stiffeners on which it can rely during closing the ventilation hole. It is worth paying attention to this when buying a membrane mechanism, otherwise deformation and further loose closing of the damper or the passage of a reverse air flow by the device are possible.

For all systems, regardless of configuration, it is necessary calculate valve positions so that the unwanted draft is blocked in all variations of the included hoods and fans as a result. The quality of ventilation is primarily affected by the correct installation of the device.

Valve location in the ventilation system

If a single air intake point is provided in the exhaust system, and it goes out into the street or into the mine through the ventilation duct, to prevent the appearance of reverse thrust it is enough to install one device in the duct.

If the system is complicated by the presence of multiple openings for natural ventilation, the following installation rules apply check valves:

A check valve is installed on all branches that combine the central air duct and the air intake point. This is important to prevent the airflow from being redirected towards the hood if it is not working.
As a rule, an additional device is mounted at the outlet of the ventilation system. In the case of absolute tightness of the channel, the installation is not necessary, but nevertheless, as practice shows, the presence of a valve in this particular place makes sense.

Ventilation check valve for natural ventilation

Basically, the check valve is placed in places with the most convenient and easy access to them. This is due to the fact that they happen from time to time clean from grease, adhering dirt and dust, otherwise, there will be no complete closure of the dampers with unwanted draft.
When designing an air duct, it is important to remember that the manufacturer in some cases places check valve directly on the hood or on the fan. In such a situation, the installation of additional protection against the appearance of reverse thrust is not required.

Trying to establish air exchange in a private house or apartment, we often make mistakes. For example, we install a ventilation check valve in order to get rid of unpleasant odors that penetrate into the premises through the exhaust ducts. We are struggling with the consequences, the real reason for the phenomenon is the lack of air flow. It is worth figuring out when you really need check ventilation valves, consider the types and methods of installing return devices with your own hands.

What is a check valve for?

The main function of the valve is to allow air to pass in only one direction, and immediately close when a reverse flow occurs. It is implemented quite simply: the flow area is closed by a damper rotating on the transverse axis inside the channel. The second option: the passage is closed with petals made of thin polymer.

Reference. All check valves used in heating, water supply and ventilation systems have a common property - high aerodynamic (hydraulic) resistance to the flow of gases (water). Hence the conclusion: you can not put air distribution elements anywhere, risking disrupting the ventilation scheme of the rooms.

With natural ventilation, air masses slowly flow from supply units to exhaust units, passing through all rooms

Before outlining the scope of the valves, let us recall an important point: most household ventilation systems work naturally. The draft of a vertical pipe or shaft creates a vacuum and sucks air, the fresh inflow compensates for the losses. In what cases is a check valve used:

When connecting the cooker hood to the shaft outlet. To maintain natural air exchange when the fan is off, the ventilation duct is connected to a tee with a return device.
If the forced discharge is organized by means of a horizontal duct laid through the wall. After stopping the fan, the valve will not allow cold air from outside to enter the room.
In forced-air ventilation systems - for flow distribution.
When it is necessary to eliminate the mistakes of designers or installers of ventilation systems at the lowest cost.

A grill with a ventilation valve helps a lot against blowing wind on the upper floors of high-rise buildings. Another case: the end of the chimney is not raised high enough above the roof of a country house or is poorly protected from the wind. But the inflow will still be needed, otherwise the weak thrust will not open the valve flap.

Mounting options for a check valve on a kitchen hood duct

Incorrect use of elements

A common mistake is installing a ventilation grill with a non-return air valve in the kitchen or in the toilet. Allegedly, it protects against odors from the neighboring apartments of a multi-storey building. Why is this approach wrong:

the reason for the penetration of unpleasant odors is the overturning of the draft in the ventilation shaft;
the thrust overturns due to the lack of inflow, the shaft of a larger section (in the kitchen) forces the smaller channel (in the bathroom) to work in the opposite direction, the air moves from top to bottom;
if you install a compensating intake device in a window or wall, both pipes will begin to draw out the exhaust air, foreign odors will disappear;
a ventilation grill with reverse petals will protect the apartment from "foreign" air by 90%, but the remaining 5-10% of gases will leak out - the sash does not fit tightly;
natural ventilation will not work without inflow.

Reverse thrust scheme - without an inflow, the kitchen shaft pulls air from the bathroom channel

Note. As in a country house, read in a separate article.

According to the requirements of sanitary standards, it is forbidden to combine the hood from the bathroom (bathroom, toilet) into one channel with the ventilation of the kitchen.
With the fans turned off, toilet odors will seep into the kitchen.
When starting two fans at the same time, it is difficult to predict the behavior of the air flow. Both valves will open, but the unit from the bathroom will "transfer" the kitchen unit, since it is installed in a straight section.

The air from the kitchen and bathroom cannot be combined into one channel, the scheme is initially incorrect

Clarification. If the fan of the kitchen umbrella is more powerful, it will "strangle" the bathroom unit and at least block the exhaust from the toilet.

Conclusion: each room needs a separate air duct, as required by the standards. Then check valves are installed at the outlets of horizontal pipes so as not to let the cold out from the street. It is allowed to combine ventilation ducts from the shower and toilet, as shown in the drawing.

It is allowed to connect the channels from the bathroom. And so that during the simultaneous operation of the fans, the air does not flow into the adjacent pipe, we join them at an angle of 45-60 °

Types of return devices

In ventilation systems, the following types of check valves are used:

air dampers - gravity and spring;
petal (membrane);
double-leaf type "butterfly".

Elements are made of plastic, aluminum alloy, galvanized or stainless steel. Some manufacturers (for example, "Vents") have combined models - a metal case, a plastic flap.

Galvanized dampers are mainly used in industrial ventilation systems. They are used to cut off the reverse flow or regulate the amount of air - manually or by an electric drive shown in the photo. Plastic ventilation fittings are used indoors, stainless steel - outdoors.

Addition. Ventilation grilles with horizontal pivoting louvers also belong to non-return valves. The principle of operation is the same - under the influence of gravity, the rectangular flaps are closed, not letting outside air inside the channel.

Let's give a short commentary on the video. Not all the words of the master correspond to reality, but he does one thing correctly: he puts an external grill with gravitational flaps.

The design and principle of operation of the dampers

A one-piece check valve consists of the following parts:

round or rectangular body;
from the inside, a flap is attached to the walls, which rotates freely on the transverse axis;
in the closed position the sash is held by a spring (not available in gravity models).

The axis of rotation of the spring-loaded damper coincides with the longitudinal axis of the pipeline, the normal position is closed. After starting the fan, the sash opens by the pressure of the air flow, when it is turned off, it automatically slams. Closing is accompanied by a characteristic sound, hence the second name of the valve - "clapper".

The two-leaf "butterfly" is arranged identically, but instead of one damper, 2 are used, the spring is installed in the middle. Both types of ventilation valves are capable of working only in forced ventilation systems. There is not enough natural draft pressure to open the spring-loaded sash.

Shut-off "crackers" as part of other ventilation accessories - connectors and mounting plates

In single-leaf gravity dampers, the axis of rotation of the damper is located eccentrically, that is, it is displaced above the axis of the air duct. Due to this, the larger half of the sash outweighs the smaller one, which is why it closes without any springs. The correct installation of the check valve plays a role here:

if you insert the element into a horizontal pipe according to the instructions (the axis of rotation is higher than the center of the duct), the damper will immediately close;
if you turn the vent valve upside down, the passage will remain open;
when installed in a vertical duct, the sash closure also depends on the position of the element.

The clapperboard for natural ventilation is installed in 2 ways: horizontally when closed or vertically, but in an upward flow. In other positions, it is difficult to predict the flap behavior; if a reverse air flow occurs, the valve may not work.

The scheme of the valve - "cracker". Due to the upward displacement, the free sash closes automatically

Household crackers can be included in other ventilation accessories - connecting nipples, wall flanges. There are also exhaust fans with a butterfly valve.

Diaphragm valves and gravity grids

In the products of the first type, the function of the main shutter is performed by a membrane made of a thin polymer film adjacent to the body or slots of the ventilation grill from the inside. The film is attached to the central axis of the valve, the edges remain free.

Under the action of natural draft or fan pressure, the extreme petals of the film bend back, letting in air. With the reverse movement of gases, the mylar membrane again adheres to the frame, blocking the passage. Lobe type dampers can be supplied with exhaust fans and grilles.

Note. It is such an air valve that is easy to make with your own hands. It is enough to attach 2 foil petals to the usual lattice, pressing with a cardboard spacer with cutouts. The manufacturing instructions are shown below in the video.

Multi-leaf grilles operate on the principle of a damper that is lowered by its own weight. Scope of application - forced ventilation exhaust ducts brought out through walls. Natural draft does not occur in horizontal pipes.

The return element is selected depending on the ventilation scheme and the installation location:

To connect a kitchen hood, use a gravity-operated cracker that matches the shape of the duct. The purpose of this valve is to maintain natural air exchange during fan inactivity.
A grate with a diaphragm valve (home-made or factory-made) is placed in the opening of the exhaust shaft if the draft is overturned by gusts of wind. It is better to get rid of odors by another method - to install wall inlet valves for.
In private homes, the local exhaust duct is often laid directly through the outer wall. To prevent cold air from being blown into the ventilation duct by the wind, install a multi-leaf exhaust grille outside.

Options for supplying fresh air to rooms using supply equipment

In mechanical ventilation systems with forced air supply, the valves are used according to the scheme and specifications drawn up by the designer. We do not recommend developing such an air exchange on your own - mistakes cannot be avoided, and the cost of rework will be too high.

Advice. Buy inexpensive plastic products for indoor installations. Galvanizing looks ugly, ventilation will have to be sewn up with drywall.

How is the check valve installed?

Installation of a multi-leaf grille and a membrane vent is not difficult and does not need a detailed description. The elements are fixed to the wall and connected to the air ducts according to the manufacturer's instructions.

One addition: when installing the external grille, it is better to insulate the wall channel. Vapors will condense from direct contact of the outgoing air with the cold walls. When the fan stops, the water will freeze and form ice.

If you decide to install a gravity check valve for the hood, consider the following nuances:

Advice. Before placing the check valve on silicone sealant, check the functionality of the circuit. Insert the cracker into the tee, turn on / stop the hood 5-10 times, changing the capacity. The flap should slam and open 100%.

Conclusion

As you can see, in home ventilation systems, the check valve is rarely used. If you profess a thorough approach to organizing air exchange, then return elements will not be needed at all. The cooker hood can be easily connected to an exhaust vent with a grill, the main thing is to provide an air supply. Exceptions are more complex circuits with 2-3 fans working alternately or simultaneously. There, valves help direct the flow or regulate the amount of air passing through.