Ventilation grille with non-return valve

The check valve on the ventilation grill serves to prevent foreign odors from entering the room from the general air purification system, as well as the penetration of air from the street through the hood.

Its function is to pass air in one direction. If you save on its purchase and installation, ventilation can work both for supply and exhaust, depending on the difference in temperature and pressure in the room and outside or in adjacent rooms. It may happen that the residents will know for certain what the neighbors are having for dinner today, and this is far from the worst option - the bathrooms also go into the ventilation system.

The principle of operation of a ventilation grille with a valve

The grille with check valve consists of three main parts: a fixed part, a moving part and a flange to which the air duct is connected.

Fixed part is a grille that plays a decorative and protective role, partially hiding the valve and protecting it from mechanical damage.It is made of plastic, usually has a rectangular shape and covers part of the wall in addition to the ventilation shaft.

Movable part looks like a rectangular or round petal that opens in one direction. Sometimes a “butterfly” shape is found. Since the system is operated in conditions of high humidity, the check valve is made of plastic that is not afraid of the aggressive effects of moisture. Metal structures are of artisanal origin and are not particularly reliable.

Flange It is a circle with a cross-section of 110–150 mm in diameter and is intended for connecting the valve to the air duct.

Types of design solutions for check valves

There are four main options for preventing backdraft into the ventilation system. Each option has strengths and weaknesses; the choice of a particular option depends on specific conditions:

Single-leaf gravity valve

The principle of operation is based on the use of the law of gravity; the sash closes under the influence of gravity in the absence of draft from the room. It is carried out in two versions for horizontal and vertical installation - opening occurs either due to the displacement of the axis on which the leaf is mounted relative to the center of the air duct, or due to a counterweight located in the device (or outside the device).

Important! It is mandatory to install a check valve of this type strictly according to the level. If this is not done, it may not close completely, or it may only operate when there is a high air pressure. It is especially important to install the valve strictly according to the level in systems with natural ventilation.

Butterfly valve using springs

It is also called "butterfly" due to the similarity of the damper petals with wings, folding when there is excess air pressure and expanding when there is no draft. Does not depend on gravity and is placed in the ventilation system at any angle. By tensioning and loosening the springs, the valve's sensitivity to pressure changes is adjusted. Most install butterfly valves in forced exhaust ventilation systems.

Blinds for ventilation grilles

The operating principle of the device is gravitational, it is placed outside the system and looks like a grille covering the air duct from the street. There are valve options for the entire grille and the size of the air duct opening being closed. Due to the small size and mass of the petals, it is suitable for natural ventilation.

Flexible membrane

The design is very sensitive to air flow, therefore it is used in both natural and forced ventilation. When air moves in one direction, the membrane bends, allowing air to circulate freely, and when the air direction changes, the membrane unbends and closes the air duct.

Important! With a strong air current, the membrane may bend in the opposite direction. As a result, the membrane can be deformed against the walls of the air duct and partially allow air to pass in the opposite direction. In such cases, stiffening ribs are additionally installed in the air duct, against which the membrane rests.

Rules for the placement and installation of a ventilation grille with a valve

The basic rule is that the system should be installed in such a way that there is no reverse draft when fans and hoods are turned on or off.

If the system has only one air intake point, from which it is directed to the street through an air duct, then installing one valve will be sufficient. In the case of a more complex ventilation topology, the following rules are followed:

• A valve is installed at each air intake point to avoid backdraft at this location.
• At the point where the air duct exits to the street, another valve is installed, for prevention - there will be no reverse draft without it only if the air duct is completely sealed.

Check valves are installed so that they are easy to reach and care for – remove dirt and grease so that they do not stick.

Before installing the valve, make sure that the manufacturer has not installed its own device in the air duct., if it already exists, there is no need to install it.

In addition to foreign odors from neighboring apartments, the ventilation shafts of apartment buildings are inhabited by birds, rats, and insects. Their waste products are not particularly sanitary, so in such systems the use of forced ventilation is mandatory. The access of air from the air duct back into the room should be prevented. You should not count on management companies to be conscientious in carrying out cleanup work.

Features of operation

In frosty weather, a crust of ice may form on louvered grilles, causing the following problems:

• The flaps no longer completely block the outlet of the air duct, and the return flow of air into the apartment begins, although insignificant, but in cold weather it is very noticeable.
• The cross-section of the hole decreases due to frozen ice, the overall performance of the hood decreases, and the fans are overloaded.

Ice is removed mechanically, but the main thing here is not to overdo it and not remove the grate along with the ice. It makes sense to install a metal structure on the street instead of a plastic one.

Finally we can conclude that by investing a relatively small amount in installing a grille with a check valve, breathing will become much easier, and in the literal sense of the word. A person can go without food for a month, without water for three days, and without air for one and a half to two minutes. Do not neglect the most necessary things, as necessary as air.