Air ventilation check valve. Non-return valve for natural ventilation - how to use and install. Types and differences

Supply and exhaust ventilation must perform its functions at any time of the year and in any weather, that is, ensure sufficient supply of clean air and removal of exhaust air. A ventilation check valve plays an important role in effective air exchange. This device is often used in natural and forced ventilation systems.

Causes of reverse thrust

Sometimes it is impossible to ventilate the room due to the return of air from the ventilation duct mixed with all sorts of odors. This happens when there is an imbalance in the volume of incoming and outgoing air due to clogging or narrowing of the common ventilation channel. Also, due to the installation of high-power fans in other apartments, the exhaust air does not have time to be exhausted outside and returns from other rooms. The upper floors are more often affected by this. Since the kitchen and bathroom ducts are connected, a fan installed in your apartment in the bathroom will provoke a reverse draft towards the kitchen.

Backdraft problem

In houses of old buildings, shafts were designed for lower air flow capacity and cannot cope with large volumes from modern powerful hoods. A check valve for ventilation helps to organize an acceptable air exchange for the room. It helps to change the amount of air removed and let it pass only in one direction, blocking the reverse movement. Thanks to it, all sorts of odors from adjacent apartments do not enter the home, and dust, fluff and insects do not fly from the street.

Operating principle and internal structure

The purpose of the check valve is to regulate and act as a damper against reverse air flow. The principle of operation of the check valve is as follows: the flaps, hanging on a central or several parallel axes, rise under the pressure of the air flow in only one direction, and when there is a lull, the petals (lamellas) lower under their own weight or with the help of springs, preventing reverse movement.

In addition to stopping the reverse flow, the valve also has the function of regulating the volume of air carried out, when by turning the damper to a certain angle, the cross-section of the air duct changes. Devices can be two-position, where there are only two positions “open” and “closed”, and multi-position, when they can be adjusted to change the throughput.

Varieties and types

Let's consider technical specifications and types of check valves in several categories:

• Based on the shape, three types can be distinguished: round; rectangular or square.
  Use the dimensions that suit the specific air duct. In everyday life, for houses, apartments, bathrooms, round valves with a diameter of 100-125 mm are used; for ventilation in factories, they are suitable with a diameter of 125 mm to 1000 mm. The length of rectangular valves ranges from 7mm to 72mm, and the width (height) - from 100mm to 1000mm.
• The manufacturing material can be metal (galvanized steel, aluminum alloy) or plastic. Plastic products are more common, as they produce less noise when opening and closing the blades. Because of their lightness, they are more used in everyday life, where the air pressure is not very high. Metal structures are typical for industrial models. They are heavier than plastic ones and close under their own weight. They are more reliable and resistant to aggressive environments and belong to the explosion-proof category. But there are also disadvantages: metal ones corrode, and condensation collects on galvanized dampers.
• The installation method can be horizontal or vertical. It is installed in one way or another based on the technical data of the valve and the corresponding design of the supply or exhaust ventilation duct.
• Control can be manual or electric. A manually operated valve is adjusted manually using a lever or gate valve, while round valves are adjusted by a valve. Such devices are used in natural supply or exhaust ventilation. The electric valve is involved in a circuit with mechanical devices (fans, hoods) and controls the volume of passing air flow automatically (damper position sensors).
• All types of valves can be divided into two groups: heated (with electric drive) and without heating. The advantages of a heated valve are that it does not freeze up in cold weather and does not accumulate condensation. Without heating it is only suitable for indoor duct use.
• According to the type of construction, there are the following varieties: membrane; petal; butterfly; lattice.
  

Application of check valve

Natural ventilation

Suitable for both supply and exhaust ventilation. IN external wall houses are installed with a supply air ventilation valve equipped with a check valve or damper. It can be equipped with an air purification filter. Using the supply valve in natural ventilation provides good access of clean air to the home with protection against backdraft and heat retention. A valve or damper allows you to regulate the intensity of air flow.

It also makes sense to install a grille with movable blinds on the supply air ducts. They direct air flow only inside the room.

The use of a flexible membrane in the ventilation grille in the kitchen is simply necessary, where the powerful flow from the hood and other rooms is discharged into one shaft to prevent its return. The membrane structure simply must be very sensitive to the slightest air movements, since there is no high pressure during natural air exchange.

In natural ventilation, you cannot use a two-leaf valve with springs, which requires high pressure to open. In this system, a device with one petal works more efficiently.

Application in case of compulsory system

This device combines well with mechanical exhaust devices, for example, kitchen hood. It is installed together with the hood.

In models where a hood with a check valve is included, it acts as a damper. When the hood is turned off, the damper closes the duct, preventing odors from entering the kitchen from the common duct. The air duct from the hood should not cover the opening to the common ventilation shaft, leaving it for natural ventilation. In addition to the grille, you can install a single blade valve or a fan with a valve.

More powerful hoods use a butterfly valve. Such designs entail additional costs. The duct from the hood leads directly to the street through the external wall, directly discharging exhaust air. To prevent cold air from entering the house, an inertial grille is installed on the outside wall.

Inside a house or apartment, in order to organize proper air circulation in all rooms, inertial grilles are installed in the interior walls, and more often in the doors. Such inertial grilles promote air movement in the direction from the rooms towards the kitchen, towards the common ventilation duct, and not vice versa.

Tee with check valve and its application

For high-quality air exchange, when installing air ducts, special tees are used, which allow you to correctly combine natural and forced ventilation.

Due to ineffective ventilation, stagnation of dampness and mold formation are often observed in the bathroom and toilet. To prevent the entry of foreign odors, as well as to quickly remove moisture, a hood combined with a check valve is used. But the fan power should not be high so that the central ventilation duct has time to cope with the air flow.

Please remember that all shut-off and control devices must be cleaned regularly to maintain their functionality.

How to choose a finished product

In the functioning of ventilation main problem is poor traction. It is enhanced by combining all types of ventilation using a check valve.

When choosing a check valve, it is necessary to take into account the compatibility of all devices and mechanisms according to the following factors:

• The shape and diameter of the channel cross-section. Choose a valve and fan that are sized to match your air duct so that there are no problems during installation. Many valve models have been developed in various round and square shapes and sizes. Typically, air ducts and check valves measuring 100 mm are used in everyday life. Square valves have proven themselves reliably and are easily mounted in square shafts.
• The material from which the product is made must match the type of system so as not to impair its functioning. After all, in natural ventilation, the shutters must respond to the slightest air fluctuation, which means they must consist of the finest material. And in industrial hoods, devices must be resistant to aggressive environments and temperatures, which is why galvanized steel or aluminum is used here.
• Purpose and device. Consider the room for which the valve is selected. It must match the power of the fan used so that it is enough to open the petals. For example, if a coefficient of 7 is sufficient for a bathroom, then for a kitchen it is 10. There are ready-made models complete with a fan with a valve.
• It is important to consider the capacity of the check valve. In everyday life, products with a throughput capacity of 4-6 m/sec are used. The volume of air removed from the apartment should not exceed the permeability of the common ventilation shaft, otherwise it will be distributed to other apartments. Otherwise, it is necessary to install a separate air duct with outlet to the street.
• Due to climatic conditions, some devices are installed only indoors, since they cannot withstand low temperatures. For example, a butterfly will become covered with ice faster due to frost. For a private home, it is necessary to take care of the characteristic wind blowing and the penetration of rodents.
  A correctly selected valve guarantees the quality of your ventilation and comfortable living conditions.

DIY placement and installation rules

Initially, we determine the installation locations of check valves in the ventilation circuit. Let's look at an example of installation in a ventilation shaft behind a fan.

1. Disconnect the hood from the power supply and dismantle it.
2. We insert the valve into the opening of the air duct and mark the mounting points on it. We take it out and drill according to the marked holes.
3. We again insert the device into the channel and similarly make markings on the wall, then, having removed the valve, we drill holes in the concrete opening using a bolt.
4. We hammer the dowels into the concrete and screw the device.
5. Carefully seal the gaps along the edges with silicone sealant to prevent air leakage and weakening of the flow power.
6. Finally, we install the hood in place.

Recently, check valves have appeared in the assortment that can be installed in front of the fan - overhead ones. Their installation is not so troublesome - it does not require dismantling the fan. A grille with a check valve is installed before the entrance to the ventilation duct or at the exit from it. You can easily install it yourself by attaching it to the ventilation opening using self-tapping screws or “liquid” nails.

At the outlet of the ventilation shaft, we use a single-leaf gravity-action valve and a double-leaf valve using springs together with a powerful fan.

DIY creation

For natural ventilation, it is not difficult to make a valve yourself.
Work progress:

Conclusion

All kinds of odors will not penetrate into the home if you install a non-return valve on the ventilation. The simplest device allows you to organize high-quality and efficient ventilation of rooms, maintaining a favorable microclimate in them.

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

To ensure the proper functioning of all devices and to prevent the return of contaminated air mixture to the room, certain devices are used.

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

Ventilation systems, their types and purpose

The need to ventilate residential and utility or purpose premises is due to the importance of creating comfortable conditions for humans.

Overmoistening or drying out the space, unpleasant odors and high concentrations of dust can lead to the development of various diseases, so install different systems air purification:

• general exchange. Natural ventilation, ensured by the physical process of air exchange occurring due to the difference in air pressure located outside and inside the building;
• forced. It is ensured by the operation of supply, exhaust or supply-exhaust 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 backdraft is neutralized.

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

Backdraft: causes and features of occurrence

A self-equipped and correctly installed check valve for ventilation will help prevent dirty air from entering the house from the air vent shaft.

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

• reducing or blocking the air flow from the supply ventilation system;
• gradual and complete clogging of the outlet openings in the natural air exchange complex;
• failure of mechanical elements and equipment components forced ventilation;
• an increase in general metabolic processes as a result of multiple penetrations into the ventilation shaft;
• improper design and distribution of air intake points throughout the house or premises.

It is important to understand that even with functional and regulated complexes of general exchange and forced ventilation, backdraft may occur.

This happens during sudden weather changes; this condition is caused by contamination or icing of the outlet channels and disruption of the overall architecture of the building.

Device for neutralizing reverse draft

Supply or exhaust ventilation using a check valve neutralizes the negative effect and the possibility of air returning to the room.

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

Types of check valves for different ventilation

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

Moreover, such devices are divided according to their design features into different types, having their own operational characteristics:

Membrane. A single-leaf device with a flexible membrane for passing air in one direction and blocking reverse movement. These devices differ in their internal design and can be with an offset axis position or equipped with a counterweight.

Petalaceae. Compact and small models 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 operates like a petal model. The peculiarity of this device is the presence not of many flexible obstacles, but of two petals.

The simplest and most inexpensive solution for a natural air exchange complex is a grille with a check valve for ventilation. It is recommended to install such devices at each entry point into a common ventilation duct that discharges the exhaust gas-air mixture outside the room.

Photo of a check valve for ventilation

The smells of neighboring apartments or houses are unlikely to be very attractive, especially when fish is being fried or soup is boiling on the stove, or if heavy smokers live nearby. These and other unpleasant odors can penetrate through the ventilation system.

This problem occurs due to the ventilation duct allowing foreign odors to pass through during reverse draft. The solution to this problem is quite simple - installing a check valve that prevents foreign odors from entering your apartment from outside.

How is a non-return ventilation valve designed and how does it work?

A non-return ventilation valve, regardless of its type and size, is a shutter, the opening of which is carried out by air flow in only one direction. When changing the direction of the air flow, the shutter closes, preventing air from flowing in the wrong direction.

For air ducts, disc-shaped (round) check valves are usually used, much less often - rectangular.

A check valve is often installed even when there are no conditions predisposing to reverse draft.

Purpose

The main purpose is to protect against draft overturning (so that air flows through the ventilation system only in the direction required in a given area, and cannot go in another). The device is intended for both supply and exhaust air ducts.

A check valve may be useful under the following conditions:

1. Insufficient supply air (for example, no supply ventilation, or it is clogged and does not function).
2. The presence of several exhaust openings in a room at once, with an increase in draft in one of them (for example, intensive operation of one fan while the others are inoperative).
3. Strong draft in the chimney during fuel combustion, with the formation of a reverse flow of air flows in a channel with natural ventilation.
4. Incorrectly installed exhaust pipes on the roof of the building (in the so-called wind shadow zone).
5. Strong exhaust hood in an apartment located in a multi-storey building.
6. It makes sense to install a check valve in winter time for rooms where ventilation is turned off during frosts (including for protection against carbon monoxide poisoning).

Where can it be installed?

A reasonable question arises about where this product can be placed. In fact, it is used in many types of rooms and on various sections of the air duct. It can be installed not only in apartments and private houses, but also in industrial and commercial premises.

The device can be installed in the following systems:

• in natural ventilation systems;
• in forced supply and exhaust systems.

It is advisable to use the device in the following buildings and premises:

• in private and apartment buildings;
• at various enterprises (production premises);
• for the kitchen and toilet, if they have hoods (in this case, the valve is placed at the opening of the ventilation shaft and prevents the hood from blowing air back into the room).

Classification

There are several varieties of this device, which differ in several parameters.

Varieties along the axis of rotation of the shutter:

1. Horizontal view.
2. Vertical view.

Varieties based on material of manufacture:

• metal, made of galvanized steel (they are used much less frequently than plastic ones, because, despite their strength, they are susceptible to rust, condensation and make too loud sounds during operation);
• plastic (without the disadvantages of metal analogues).

Varieties by scope:

1. Heated (for conditions where the device will be in contact with warm and cold air alternately, which may lead to the formation of ice).
2. Without heating (for rooms and systems in which there is no risk of freezing).

Types of check valve according to product structure:

• single-leaf;
• bivalve (the so-called butterfly or petal type);
• membrane;
• "blinds".

Varieties in shape (for ventilation ducts of different sections):

1. Rectangular.
2. Round (in the form of disks).

Where is it sold and how much does it cost?

You can purchase a check valve at ventilation product and equipment stores. The cost depends on what type of valve and what size you need.

Approximate cost of various models:

• model VENTS KOM 125 mm – 290 rubles;
• VENTS COM 100 mm – 250 rubles;
• VENTS COM 150 mm – 290 rubles;
• VENTS COM 200 mm – 320 rubles;
• VENTS COM 315 mm – 550 rubles;
• VENTS COM 1600x350 mm – 2500 rubles;
• VENTS GFK (gravity tee) 160 mm – 830 rubles;
• VENTS COM 250 mm – 420 rubles;
• VENTS GFK (gravity) 140 mm – 760 rubles;
• VENTS COM (rectangular) 1400x200 mm – 2010 rubles.

Do-it-yourself check valve for ventilation (video)

How to choose?

You need to choose a check valve correctly, paying attention to the characteristics of your ventilation equipment and selecting a model with the appropriate parameters.

The first thing you should think about is the ambient temperature where the product is used. In addition, think about the speed at which blockages appear, since frequent blockages are typical for ventilation operation under conditions of regular intense wind (usually in open areas).

Even such data is already enough for a more or less competent selection of a product. If operating conditions are too cold, it is better not to use the butterfly valve, as it will simply freeze up. But the problem with frequent blockages cannot be solved - valves of any type become dirty equally quickly.

You also need to think about what type of fan is installed, for which the valve will be installed (if we are talking about a forced ventilation system). If the hood works too poorly (with low draft), then the check valve will simply become an air duct damper, but will not perform its main function.

You need to select a fan with such power that it corresponds to the operating conditions. For example, for a kitchen you need to take into account the coefficient value of 10, and for a bathroom – 7. Don’t be afraid to buy an additional exhaust fan to increase draft.

Installation rules

When the ventilation system has only one air intake point through which it exits into the shaft or environment(on the street, for example) - installing one valve is enough. But if the circuit is somewhat more complex, you will have to install several valves at different points.

The second case requires compliance with the following installation rules:

1. A separate valve should be installed for each branch of the air intake stack and main air duct. This is necessary to prevent redirection of air flow towards the hood when it is turned off.
2. It is recommended to install another valve at the ventilation outlet. This is not necessary if the channel is completely sealed (but even in this case it is recommended to install an additional device).

It is important to mount the device in places where it will not be difficult to reach. Contamination with dust and grease deposits is common, so the product will need to be cleaned regularly.

When choosing equipment (hood, fan), always keep in mind that the manufacturer may have already installed a check valve in advance. Then install additional device no need.

Household ventilation should be equipped using round or rectangular air ducts with basic parameters (dimensions). If there is a need for alternating operation of forced (fans) and natural ventilation systems, then two methods of fastening the check valve can be used:

1. Installing a tee directly after the ventilation grille, with mounting the valve on a branch to ensure natural ventilation (as in the photo above).
2. Purchase and secure a grille with 2 holes for both types of ventilation (for example, at the bottom there are grille slits for natural ventilation, and above them there is a round hole for connecting the exhaust duct). But it is better to use the first method.

How to do it yourself?

If you decide to save money or cannot find a suitable model, you can try making the valve yourself.

You will need the following materials:

• Mylar tape (as much as possible);
• tee with diameter cover;
• a self-tapping screw with a spring that matches its diameter (can fit on it);
• film or flexible plastic;
• long ruler;
• stationery knife.

The film must meet the following criteria:

1. Its dimensions should be slightly larger than the outlet (hole) of the ventilation duct.
2. When selecting a film, you should be guided by the fact that the thickness directly depends on the parameters (in terms of size) of the cells - the larger they are, the correspondingly thicker.
3. Do not use film with a rough surface.
4. Crumpled material is not suitable for making membranes.

Manufacturing instructions (also available in the image diagram with details above):

1. First of all, we draw markings on the grid. Based on this drawing, we will mount the future halves of the membrane.
2. Using tape, secure it to the grill large size film (but not yet cut). Please note that the tape should not be taut when attaching.
3. Next, using a knife, we cut out the outline of the future shutters (we make right and left outlines, like shutters on windows).
4. The final structure must be airtight. You can check this like this: when closed, the membrane should normally completely cover the lattice holes and there should be no various defects in the form of irregularities.
5. Be sure to glue the sash fastenings as thoroughly as possible.

If everything is done correctly, the homemade version will be no worse than the purchased one.

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

The main factors for the appearance of reverse thrust

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

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

Installing a Vent Check Valve 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 low, but installing a valve in already functioning air ducts is not an easy and time-consuming job.

Types of check valve

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

Single leaf gravity action

The air flow leaving the room is able to exert pressure on the valve flap, thereby opening it slightly for the free exit of air. If there is no movement or reverse thrust appears This pressure does not occur on the damper and it closes under the influence of gravity.

If the installation was carried out according to all the rules, reverse gravity the valve can be used with natural ventilation, since it has minimal resistance to opening the sash. There are two options similar installation:

1. using a counterweight located outside or inside the device;
2. deviation of the placement of the axis on which the leaf is mounted relative to the middle of the cross-section of the air duct channel.

Pay attention! Closing the sash 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 increased air flow in the ventilation system will be necessary to open the sash.

Double leaf with springs

This is the so-called “butterfly” device, equipped with 2 curtains. If there is excess pressure, they fold on a certain side, and if there is no pressure, they are closed by springs. Since the operation of the mechanism does not depend on gravity, such a device can be placed at different angles.

This option has worked 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 pressure in the air duct on which 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, a grille with a check valve for natural ventilation is very similar to window blinds. This device has a similar operating principle single-leaf version - gravity. The use of several flaps instead of one is due to the compactness of the mechanism in the open position, which is quite important for external components of the ventilation system.

Dimensions of ventilation grilles with a check valve for natural ventilation designed for standard parameters of boxes intended for hoods. As for the device for preventing unwanted draft, it can be placed either on the entire grille or only on the opening for natural ventilation.

Using a flexible membrane

The working principle of a 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 adjacent to the perimeter.

If there is a risk of the membrane changing due to powerful backdraft, auxiliary stiffeners are required on which it can rest during closing the ventilation hole. You should pay attention to this when purchasing a membrane mechanism, otherwise deformation and further loose closure of the damper or the device allowing reverse air flow may occur.

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

Valve location in the ventilation system

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

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

• A check valve is installed on all branches that connect the central air duct and the air intake point. This is important to prevent airflow from being redirected towards the hood if it is not working.
• As a rule, an additional device is installed at the outlet of the ventilation system. In the case of absolute tightness of the channel, there is no need for installation, but still, 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 occur from time to time clean from grease, adhering dirt and dust, otherwise, the dampers will not close completely when unwanted draft occurs.
When designing an air duct, it is important to remember that in some cases the manufacturer places check valve directly on the hood or on the fan. In such a situation, installation of additional protection against reverse draft is not required.

The main task of room ventilation is to remove smoke, unpleasant odors, steam outside and replace the air. Previously, natural air circulation was used everywhere, but modern apartment renovations do not allow this option to function effectively. A kitchen exhaust fan with a check valve solves this problem. Without forced aeration, mold will begin to appear in the corners, and the walls will constantly be covered in soot from cooking.

Operating principle of a check valve

There are exhaust, duct and supply fans, the design of which includes a check valve. They are used to gradually replace air. The advantage of a valved exhaust fan over an air conditioner is that the former creates a flow fresh air, and does not work with what is already available.

Such hoods are often used not only by residents of apartment buildings, but also by private ones. They are used for:

• kitchens;
• laundries;
• bathrooms and toilets;
• sanitary compartments;
• office smoking rooms, etc.

The hood has quite simple design. Check valves are divided into three types:

1. Spring-loaded. It is also called self-closing.
2. Operated (manually or electrically).
3. Passive. Closing or opening of the lid occurs under the influence of air flow.

The spring type is usually installed in the kitchen or bathroom. The cover is always open while the engine is running. When the fan turns off, the check valve cover closes under the action of a spring. It does not provide complete sealing, but protects well from foreign odors.

Hoods with controlled electric valves are provided when it is necessary to create an automated ventilation system. They are used in industrial premises: warehouses, in some workshops, factories, as well as in sales areas and large offices. Such ventilation prevents the formation of fungus, mold and condensation.

Passive ventilation is the least common. Sometimes it can be used for a regular kitchen hood.

Check valves can be made with or without heating. Thanks to this function, you can prevent the formation of ice in winter. This is necessary if the device goes outside. An unheated hood is used indoors only.

Fan selection

Hoods for cellars, bathrooms and kitchens are produced in different modifications and sizes, as well as with in different forms blades. Some models have an inertial grille. It works on the principle of blinds. After the engine has finished running, the grille closes. There are also economical models, in which a timer is built in. With its help, you can set the periods of operation of the device.

When purchasing a device, you should consider the presence of a power regulator, as well as manual fan shutdown. For rooms with high humidity (bath, shower, steam room, etc.), it is worth choosing models that have an appropriate controller. It is also important to consider some factors when choosing:

1. The volume of the room in which ventilation will be installed.
2. Object type.
3. Number of residents.

Sufficient power of the device will ensure good ventilation and prevent mold and mildew from forming. This can significantly improve your quality of life.

Kitchen hood

Food preparation takes place every day in the kitchen. During this large number grease, smoke and steam settle on the walls, curtains and rise to the ceiling. Natural ventilation has often been faulty for a long time. To avoid soot settling on surfaces, you need to install an exhaust fan with a check valve.

The most simple option installation is above the stove, and the outlet can be made directly into the ventilation shaft. If the apartment has old windows, then you can install a fan in the window. For a private house, it is necessary to make a hole in the wall to remove stale air.

Productivity (volume of pumped air per hour) is a very important parameter. For the right choice For hoods, you need to know the volume of the kitchen: multiply the height by the length and width. Sanitary standards stipulate that a certain number of complete air replacement cycles must occur in the room. For the kitchen, an indicator from 8 to 12 is applied. There is also a safety factor, that is, losses that may occur due to a ventilation malfunction. Typically a value of 1.3 is used. To calculate the required productivity, multiply the volume, the multiplicity and this coefficient.

The second point that you should pay attention to when buying a hood is the noise level. It is created by a motor that rotates the fan blades.

Don't forget about power. The higher it is, the better the exhaust air leaves the room. The check valve will prevent it from returning to the kitchen. But a powerful hood costs much more than a mid-range fan.