Ventilation grille with check valve: device and types + installation recommendations

Sometimes ventilation not only removes exhaust air outside, but also becomes a source of unpleasant odors. This happens as a result of the entry of air masses from adjacent rooms or from the outside due to the occurrence of reverse draft.

To solve this problem, a ventilation grille with a non-return valve was invented, blocking air flows trying to enter the room. In this article we will get acquainted with the design features of such a grid, its main advantages and reasons for use.

We will also analyze the process of self-installation and the rules of operation of this device.

Design and advantages of a grille with a valve

The model includes three main parts: fixed, movable, and a flange for connecting the air duct.

The stationary part is the grille itself. It acts both as a decorative element and as a barrier that protects and closes the valve from accidental damage.

Since the grille closes the ventilation hole, smell and all kinds of small particles do not penetrate from the street. When the outside temperature drops, the grille prevents heat loss

It has a rectangular geometry and is made of plastic. The structure should cover not only the ventilation shaft, but also cover a little of the wall.

The mobile part visually looks like a petal, round or rectangular, although sometimes you can find an unusual shape - a “butterfly”. It only opens in one direction.

The valve for gratings is made of plastic, since it has to be used in conditions of aggressive moisture.

The flange in cross-section looks like a circle. Its diameter is from 11 to 15 cm. The valve is integrated into the air duct using a flange

This ventilation grill has a number of advantages:

1. It will protect from both cold and too warm street air.
2. No insects or dust will enter the room.
3. The room will be protected from foreign odors.
4. The presence of a noise-absorbing effect will prevent the penetration of extraneous sounds.
5. Easy installation and maintenance.
6. Aesthetic appearance of the decorative grille.

The main disadvantage is that if the temperature is below zero, the blinds or petals may freeze. To solve this problem, a heater is built into the system.

When is a grille with a check valve needed?

The advisability of installing a grille with a check valve is due to the presence of reverse draft in the ventilation system.

Therefore, if this phenomenon is absent, there is no urgent need for it, but for prevention it is still worth installing a grille.

A high-quality valve shutter should be so sensitive that it can quickly respond even to weak air movement

The following factors can cause backdraft:

1. Lack of air flow into the room or reduction in its volume.
2. Debris getting into the hole.
3. Failure of elements that control air flow.
4. Operation of high power hoods.
5. The wind that was not taken into account when designing the house was constantly blowing.
6. The presence of several pieces of equipment in the ventilation system, the air outflow operating simultaneously.

All these circumstances create conditions for the appearance of reverse thrust. In this case, pure oxygen does not enter the room. There is no guarantee that at least one of the listed factors will not appear. It is better to protect your ventilation system by installing a grille with a check valve.

Possible problems

During operation of the device, the following troubles may occur:

• valve jamming (the reason is a violation of the position of the element during installation);
• icing of valves;
• deformation of the locking mechanism (this can happen in cheap models with high traction);
• the appearance of unpleasant pops when closing the sash.

It must be taken into account that the valve prevents the natural movement of air. If this is unacceptable, then it is better to remove the element.

Design features

Any ventilation grille of this type consists of three components:

1. Stationary part. A decorative grille that simultaneously acts as a full-fledged design element and a barrier that protects internal structural elements from damage. Most often, the lid has a rectangular shape, not only completely covering the body, but also partially protruding onto the wall surface for fastening.
2. Movable part. It looks like a rectangular or round plate that can open only in one direction. The valve is often operated in conditions of high humidity, so the most suitable material for its manufacture is plastic.
3. Flange for connecting the air duct.

Grate design with check valve

The standard diameter of the device can be from 110 to 150 mm. As a rule, such dimensions are sufficient to implement the vast majority of domestic ventilation system projects.

How does a ventilation grille with a check valve work?

The essence of the device’s operation can be described as follows. Contaminated exhaust air from the living room, kitchen or bathroom is removed from the premises. We are talking only about forced circulation systems, since the force of the natural air flow will not be enough to open the valve (with the exception of membrane-type devices).

The air flow from the fan, on the contrary, easily overcomes the damper resistance. The passage opens and air masses are removed from the room. As soon as the fan stops operating, the air flow stops and the damper returns to its original state.

The design of the valve is such that it easily opens only in one direction. If unwanted air flow from the street or from a ventilation shaft tends to enter the room, it will be reliably blocked by a damper tightly pressed to the body of the device.

Causes of reverse thrust

Sometimes it is impossible to ventilate the room due to the return of air from the ventilation duct mixed with various types of odors. This occurs when the balance of incoming and outgoing air is disrupted due to a clogged or narrowed common ventilation duct. In addition, due to the installation of powerful fans in other apartments, the exhaust air does not have time to be extracted and returns from other rooms. The upper floors are often affected. Since the kitchen and bathroom ducts are connected, a bathroom fan installed in your apartment will create a backdraft towards the kitchen.

Backdraft problem

In older homes, ductwork was designed for lower air flow rates and cannot handle the large volumes of air coming from today's high-efficiency hoods. The reverse draft valve helps to organize air exchange acceptable for the room. It helps change the amount of air outside and allows it to flow only in one direction, blocking reverse flow. Thanks to this, all kinds of odors from neighboring apartments do not enter the house, and dust, fluff and insects do not fly in from the street.

Device and principle of operation

A ventilation grille with a check valve consists of a protective housing, a mounting flange, a front decorative panel and a damper. The valve flap is able to open due to the forced circulation of air masses moving under a certain pressure. The grille is connected to the air duct using a flange, which is available in different sizes and is fully compatible with all types of air ducts. For the manufacture of grilles with a check valve, plastic is mainly used, which is due to the operation of the device in conditions of high humidity, where the use of metal components is impractical.

The principle of operation of the check valve is as follows: exhaust air masses leave the room through the decorative trim and, under a certain pressure, pass through the valve, lifting the damper. When the air flow pressure drops, the valve valve closes and acts as a reliable barrier to street dust, insects and unpleasant odors. Models are often installed in kitchens and bathrooms adjacent to similar rooms in neighboring apartments.

The check valve prevents the penetration of air masses and noise from adjacent rooms, which compares favorably with a conventional ventilation grille that is not equipped with additional protection. Installation of gratings can be done both from the side of the room and on the external wall of the building. The devices are connected to the end of the air duct, and the joints are additionally sealed.

Adjustment and Settings

The process of regulating the parameters of the ventilation system comes down to ensuring the level of air inflow and outflow specified in the project in all sections of the network. This is quite difficult to accomplish without specialized equipment and experience.

However, you can try to make adjustments based on the following guidelines:

• It makes sense to remove excess air to sections of the network with a capacity below the design values.
• The permissible tolerance for air flow in supply and exhaust units is 10%.
• The dampers located closest to the fan are adjusted first. The required level of air flow resistance is set by smoothly turning the damper.
• The fan power is adjusted by changing the rotation speed of the blades.

Note! If it is not possible to adjust the valves in any part of the ventilation system, a steel membrane can be installed, which creates a constant resistance to the flow in the duct.

Dampers and ventilation valves allow you to quickly and effectively regulate the parameters of the ventilation system. Control can be carried out manually or automatically, which allows you to build a climate system of any complexity: from the simplest solutions for private houses and apartments to complex and extensive ventilation networks of large buildings or industrial facilities.

In-house produced muffler:

Advantages and disadvantages

Stable consumer demand and high popularity of grilles with a check valve are due to a number of undeniable advantages of these devices .

• The valve prevents the draft from tipping over and prevents the penetration of air masses from adjacent rooms or from the street.
• The high noise-absorbing effect reliably protects the room from extraneous sounds coming from neighboring rooms and street noise.
• The modern aesthetic appearance of decorative grilles allows devices to be placed in rooms for any purpose without the risk of cluttering the interior.

• Simple installation and low maintenance requirements make grilles one of the most practical devices for this purpose.
• The devices are available in a wide range with a wide variety of sizes, colors and designs. This greatly simplifies the selection of the desired model and allows you to purchase a grille to suit any interior.
• The low cost of products makes them even more accessible and popular.

The disadvantages of the devices include the risk of the dampers freezing in winter and the not very high performance of most models. However, the problem of freezing of the device is easily solved by installing a built-in heater.

Epilogue

Let someone say that installing a check valve on ventilation is nonsense and is not worth wasting time and money on. But still, many of those who have done such work say that the air exchange in the room has improved significantly after their work. Humidity has decreased, unwanted odors have disappeared, etc. Based on the reviews, it's safe to say that the vent check valve is worth the cost of installation. After all, our health depends on what we breathe, so any improvements aimed at cleaning the air will be beneficial.

Non-return valve for forced ventilation in the section

In any case, there is nothing worse than installing such valves, which means it’s worth trying, first, to at least install a valve made by yourself, because it won’t cost anything. Well, having understood the advantages of such equipment, you will probably want to purchase a more advanced factory product.

Main types of ventilation grilles

According to the type of locking device, a ventilation grille with a valve can be:

• single-leaf gravity;
• petal;
• membrane;
• butterfly

The principle of operation assumes that a correctly directed air flow lifts the locking device and passes freely into the air duct. The reverse flow presses the locking part against the supporting surface of the grille body and locks it.

A single-leaf gravity structure is a round or rectangular locking element eccentrically mounted on an axis.

The lightweight flexible membrane opens and closes with a low-intensity air flow. Typically, ventilation grilles with a check valve for natural ventilation are equipped with membranes made of lightweight synthetic materials.

The compact petal design is similar to gravity blinds.

Butterfly valves have locking flaps that fold when opened by air flow and are closed by a spring. Thanks to the spring they can be installed in any position.

Troubles that may arise

Everything seems clear and logical: foreign odors in the apartment are very unpleasant. Rollover in a private home is no less unpleasant, but also dangerous. In principle, with a correctly designed system, such phenomena should not occur and the causes of their occurrence must be dealt with. But not everyone has the opportunities and resources. It is easier to install a check valve for ventilation. This is true, but there are nuances that are worth knowing.

• A valve installed in the vent interferes with natural ventilation. If you want natural exhaust to work, you need to think through the connection so that the valves do not interfere.
• Even “quiet” plastic valves slam when closed, sometimes making quite loud sounds. These pops are stronger, the stronger the thrust. In variable winds they are very annoying. So you will have to come up with something to make the valve “quieter”.

• 
  This is the quietest valve - an elastic membrane, but not very reliable

• Some fans or kitchen hoods have a built-in check valve. If the regular one doesn’t suit you for some reason, you need to delete it. Then you can install a separate one. Two valves on the same channel may not get along. Or rather, the exhaust duct is unlikely to work.
• For normal operation, the check valve must be regularly maintained - cleaned, checked, lubricated axles. Considering that it is not always easy to get to him, this is at least inconvenient. So provide access for cleaning and inspection.

As you can see, installing a check valve on the 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.

Materials and shapes of ventilation grilles with check valves

Depending on the materials, the ventilation grille with a check valve can be:

• plastic;
• metal made of galvanized steel.

The main material is lightweight, corrosion-resistant, inexpensive, easy-to-install plastic. However, it does not tolerate high temperatures and such products are more often used for indoor installation. For outdoor installation, metal models are usually used. To prevent winter freezing, heated structures are used.

In accordance with the shape, the ventilation grille with a check valve is available in the following cross-section types:

• round;
• square;
• rectangular section.

When choosing a specific grille, you should focus on operating conditions, the shape and size of the entrance to the ventilation duct.

The nuances of self-production

Self-production is advisable if the box has a non-standard geometric shape or dimensions. The simplest design is a membrane or single-leaf device. During manufacturing, it is necessary to monitor the tight fit of the sash, eliminating the knocking of the plate due to a change in the direction of the air stream.

Selection of materials

The most popular material for the production of ventilation systems is plastic. It is lightweight, does not corrode, and is cheap. However, it is better not to use it on the external parts of the channels.

Products made of galvanized steel can be used in conditions of frequent temperature changes: they are strong and durable.

However, this material is susceptible to corrosion and is heavy compared to plastic.

Choice of product shape

It all depends on the size of the duct. For small pipe sizes, you can use a round one. In other cases, a square or rectangular device is suitable.

Existing varieties of such gratings

There is a classification of ventilation grilles equipped with a valve.

Depending on the type of locking device, they are:

• gravity single-leaf;
• petal;
• membrane;
• butterfly

Ventilation grilles are made of plastic and galvanized metal.

Nowadays, ventilation grilles with a check valve are very popular. With their help, air flows are controlled. Such products are often used in bathrooms and toilets.

The former cannot tolerate sub-zero temperatures, so they are mainly used for indoor installation. They have light weight, high corrosion resistance, long service life, and low price.

Metal grilles are usually installed outside. To prevent them from freezing in winter, heating is used. The shape of the gratings can be rectangular or round.

They are characterized by high heat resistance, so they are used for installation in hot shops, large kitchens, and outside buildings. The big disadvantage of these products is their susceptibility to corrosion and heavy weight.

Type #1 - single-leaf gravity grille

This model has an extremely simple design. The locking element here has the shape of a circle or rectangle. It is a structure with a locking mechanism eccentrically fixed to the axis.

The work is based on the fact that the air flow, having the correct direction, moves the damper and then moves freely along the air duct. An air avalanche of reverse direction pulls the valve to the frame of the grille and closes it.

The working leaf of the gravity single-leaf grille opens under the influence of the pressure of air masses coming from the room. The advantage of the design is that it works automatically

There are two versions of such models - with a displaced damper mounting axis relative to the axis of the air duct pipe and with a counterweight located outside or inside the device.

The device is installed strictly vertically or horizontally. Otherwise, the damper will not close completely and will not provide adequate protection of the room from the outside atmosphere.

Type #2 - membrane type of device

This type of grating is the most common. Here, a light and flexible membrane acts as a sash. Since it has little resistance, it closes under the influence of gravity.

Due to its simplicity and reliability, the model is used in ventilation systems where air flow circulates naturally.

There are no mechanical elements or complex mechanisms in the design of the membrane grid, therefore, they are reliable and durable. The membrane itself is made of weightless synthetic material

To prevent membrane deformation as a result of increasing pressure of air jets in the system, these models are reinforced with stiffeners. The membrane partition rests on them if excess draft occurs.

Type #3 - petal grille models

The petal design is similar to the gravity model. Here the valve is shaped like a louvers. Its work is based on gravity.

In a basement or garage, it is better to install a galvanized petal grille. The valve regulates the air supply by turning it clockwise

The device functions more efficiently if it has several doors. The valve on such a grill can be installed only on the hole or over its entire area.

Type #4 - model with a butterfly-shaped locking device

The butterfly valve has two curtains. It closes under the influence of built-in springs. This model can be installed in any position.

Spring devices operate exclusively in ventilation systems with forced ventilation. They cannot work in networks with natural draft

Having chosen such a grille, you need to check how the springs work under the influence of air pressure. In the latest models, the spring force can be adjusted.

DIY installation

Installing the valve yourself is easy. The device is simple, step-by-step instructions clearly explain the principles of installation. But there are some tricks here.

In the kitchen with a hood

Modern hood models are usually equipped with this device. If it is not there or for some reason you are not satisfied with its work, you can install the device yourself.

Recommendations:

• It is better to install the device not in the hood body, but at the outlet of the tee. But it needs to be mounted in an inverted position. In this case, the damper will open when the fan is running.
• Tees are placed vertically and preferably not near the ceiling. In this case, the ventilation duct can be covered entirely with a decorative box.
• There should be ventilation grilles on both sides of the box.
• If a firecracker is installed, the tee cannot be placed near the shaft exit. Here the air flow turns, forming a vortex. Therefore, the damper may not close completely and allows odors to pass through.
• The damper in the hood should only be placed horizontally. In a vertical position or at an angle, it does not close tightly.
• The valve is unpacked, the area is lubricated with silicone sealant, the device is inserted into place and adjusted.

Source

How to choose a grille with a valve

Before choosing a specific grille model with a check valve, you should focus on some important points:

• Carefully inspect the ventilation shaft opening, assess its condition and measure geometric parameters.
• Pay attention to the manufacturer. Slightly more expensive models under a well-known brand are a guarantee of quality and durability. Of course, you can find high-quality and reliable products from less famous brands.
• When purchasing a ventilation grill, it would be a good idea to ask the seller for a quality certificate. This document will not only provide comprehensive information about the product, but will also serve as an additional guarantee of quality.

Note! It is important that the device is made from environmentally friendly materials and fully complies with all standards and requirements.

Installation Tips

Due to the simple design and low weight of the gratings, their installation can be carried out independently. The exhaust grille should be installed on the surface of the wall, however, some models can be mounted in a ventilation shaft. The first stage of installation should be connecting the device to the air duct, which is done using a connecting flange. It is recommended to foam the space between the air duct and the wall. Next, you should wait until the polyurethane foam hardens, and then remove its excess using a stationery or construction knife.

The next step will be fixing the grille to the load-bearing surface, which is done using self-tapping screws or dowels . The choice of fastening element depends on the weight of the model and the material used to make the walls of the building and the body of the device. Once the grille is in place, you can begin a test run of the device. Ventilation grilles with a check valve are an important part of exhaust ventilation. The devices reliably protect the space from external flows and help create a favorable indoor microclimate.

Installation instructions

To install a check valve for ventilation with your own hands, you will need:

• electric drill;
• silicone sealant.
• studs with screws;
• the valve itself;
• hole puncher;

Correct sequence of work:

• wiring is connected;
• a decorative cover is installed.
• Drill holes for the studs using an electric drill or hammer drill;
• The fan, if any, is removed;
• The entire kit is checked (the list is provided on the package insert), although it is better to do this at the time of purchase;
• The fan is inserted into the air duct and fixed with self-tapping screws;
• Markings are made on the wall for fastening;
• Drill a hole in the wall for the electrical wiring. The air duct can be replaced with a plastic box or retro wiring, which, on the one hand, looks impressive, on the other hand, is expensive, and the wiring is laid directly in the wall;
• a new fan will be installed;
• the connection between the fan and the wall is sealed with silicone sealant (some kits provide rubber sealant for this purpose);
• the entire system is tested;
• First, install the grille at the fan inlet, then the check valve on the fan. If it is gravitational, the horizon of the damper axis is checked - when deflected, the petals cannot close;
• the operation of the fan is checked;

If dampers are installed at suction points with natural draft, no instructions are required. Everything is very simple there. The procedure is described in the instructions printed on the insert.

Valve installation diagram for natural draft (scale) and forced draft (butterfly).

Installation of ventilation grille

Before installation, a ventilation grille with a backdraft valve is checked to ensure that the valve is properly oriented so that the correct air flow will open the locking element. You should also carefully study the product passport and fully comply with all the requirements given therein.

If the kit does not include fasteners, you must purchase the required products. The surface is being prepared for installation of the grille flange. Places for fasteners are marked, holes are made for dowels, and dowels are installed. The product is installed with self-tapping screws. After installing the grille with an effective non-return valve for ventilation, leaks in the joints are sealed.

Selection rules

The choice of model depends on the design of the room and the design features of the ventilation.

The choice of grille element depends on the design features of a specific ventilation system; in some cases, the parameters are specified in advance. You can also select a part using special monograms designed for specific requirements. For large systems, the main selection criteria are air flow and air speed, so they require custom-made grilles and equipped with a special regulator. In addition to technical requirements, attention must be paid to aesthetics and design of elements.

In most cases, the choice of a specific model depends on the shade of the part, the need for adjustable blinds and a fine mesh. Additionally, noise and aerodynamic properties, characteristics and areas for installation, and installation location, for example, on the floor, ceiling, wall or door, are checked. An important parameter is the absence of problems during maintenance, the size of the air duct or opening, as well as the ability to consume air during operation. At the beginning, you should always take into account the dimensions of the ventilation duct and its geometry, as well as operating conditions.

The choice of gratings for industrial premises should be entrusted to professionals. If we are talking about parts for apartments or houses, you can select them yourself if you have a design or diagram of the ventilation system.

Installation and operation

The hood grille is installed on the outside of the house

A ventilation grille with a check valve for natural flow ventilation is installed on the outer part of the wall; some parts are allowed to be fixed in ventilation shafts. At the first stage, the device is connected to the air duct using a connecting flange, filling the gap between it and the wall using sealant. After the foam has hardened, its excess is removed with a stationery or construction knife.

At the next stage, the grille must be fixed to the load-bearing surface using dowels or self-tapping screws. You need to select a fastening element taking into account the weight of the part and the material from which the walls of the building and the body of the grille are made. After completing the installation work, the device can be started in test mode. If the installation is carried out correctly and without errors, in compliance with all requirements and safety rules, the grille will operate as stably as possible.

A properly installed grille with check valve is an important part of the hood and ventilation system. With its help, you can reliably protect the air duct from external flows and create an ideal microclimate in the room.

Types of kitchen ventilation systems

Effective air exchange, which creates a healthy microclimate, consists of two processes - the influx of fresh air from the street and the removal of polluted air from the room. The kitchen is the place where air pollution is most intense. Here water vapor, gas combustion products, evaporation and smoke are added when cooking.

There are the following types of kitchen ventilation systems:

• General natural ventilation . This is a ventilation system that is put into operation along with the house and provides a sanitary minimum air exchange established by the state standard. There are general ventilation outlets in the kitchen, bathroom and toilet. They are framed by simple ventilation grilles.
• Additional forced ventilation. Additional ventilation can be exhaust or supply and exhaust. The installation of additional equipment is initiated by the owner of the property. Air exchange is carried out between housing and the street through the ventilation shaft.

• Purifying (recirculation) ventilation, without external air exchange. This hood works by forcing air through filters. The purified air is released back into the space from which it was taken. There is no gas exchange between the kitchen and the street.
• Combined hoods are devices that have access to a ventilation duct, but can operate in recirculation mode.

In the vast majority of residential buildings, ventilation is provided using natural draft and is designed to remove polluted air from the living space. There are no channels for supply ventilation. Their role is played by vents, windows, doors and even cracks in old window frames.

Note! Residents of houses that were built 20 or more years ago, when replacing window frames with sealed plastic, are faced with the problem of stuffiness in the house. The reason for this is a decrease in air flow from outside.

In modern houses where there is a ventilation shaft channel for air exchange, the exit to it is closed with a ventilation grille.

We recommend that you read: Purpose and use of industrial exhaust fans

Single-leaf product based on gravitational action

Such a device operates on flows directed from the room with pressure exerted on the valve leaf. In the presence of reverse draft, there is no pressure, and the flap closes under the influence of gravity.

This device is used with natural ventilation. When installing, be sure to observe the placement of the valve based on its design features. This is done horizontally or vertically.

Photo 1. Scheme of installing the product horizontally and vertically.

Double leaf version with springs

The valve, in the form of a butterfly, has two curtains in its structure. They fold under the influence of pressure forces from a certain side or slam shut when there is no pressure factor. The slamming mechanism is due to the action of built-in springs.

Such a device can be placed on the floor at any angle.

As practice shows, such a device works clearly in the presence of a hood. When purchasing such a device, be sure to test the springs for air pressure. Modern devices require adjusting the force of the springs.

Blinds on the ventilation grille

The valve installed on the outdoor grille may be in the form of a louvers. The operating principle is similar to a single-leaf product and is based on gravity. When using several sashes, the operation of the device is more efficient. Dimensions are based on possible hole patterns. The valve can be installed over the entire grille area or exclusively on the hole.

Photo 2. An example of ventilation grilles with blinds.

Use of flexible membranes

The use of a membrane version of the valve is due to the action of the air flow, which will change the position of the plate.

One direction of flow serves to open the membrane, the other vector of pressure closes it. A strong backdraft process can deform the plate. To avoid such a situation, you need to purchase a product with stiffeners. If you try to save money and buy a device without ribs, then there is a possibility of deformation of the product. The result will be the passage of air in an unwanted vector.

Sources

• https://sovet-ingenera.com/vent/montazh/ventilyacionnaya-reshetka-s-obratnym-klapanom.html
• https://TopVentilyaciya.ru/ventilyaciya/elementy/reshetka-s-klapanom.html
• https://stroy-podskazka.ru/ventilyaciya/reshetki-s-obratnym-klapanom/
• https://ventilaciya.info/ventilyatsiya/ventilyatsionnaya-reshetka-s-obratnym-klapanom.html
• https://StrojDvor.ru/ventilyaciya/ustrojstvo-ventilyacionnoj-reshetki-s-klapanom-obratnoj-tyagi/
• https://oventilyacii.ru/ventilyaciya/ventilyatsionnaya-reshetka-s-obratnym-klapanom.html

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