Check valve ventilation: how to arrange ventilation with a check valve on the extractor

The emergence of reverse thrust - a common phenomenon which has many negative consequences. Install a check valve on the ventilation can solve the problem.

You need to know the constructive versions of these devices, their pros and cons, as well as the rules of placement and installation of exhaust systems.

The causes of back draft

In order to decide whether to install a check valve, it is necessary to find out the possibility of reverse thrust in the house ventilation system.

Understanding this process will allow to plan and implement ventilation indoors.

With burning match can easily check the direction of air flow in the vent, and estimate the flow rate

The principle of operation of ventilation is based on the law, that at any time the volume of incoming and outgoing air from the room is the same. Thus, the reverse thrust in the extract occurs if the total flow of the other points of entry and exit of air is directed from the home. There are several main reasons for the occurrence of such an effect.

Often the reverse thrust is caused by a significant reduction or cessation of flow into the room through the air extraction. This may result from the gradual clogging of the holes, and in case of forced circuit - wear or breakage of the mechanisms responsible for air circulation.

Also, reverse thrust may contribute to the emergence of a sharp increase in the volume of air exiting through one of the exhaust device. For example, when the hot air heating furnace with combustion products rapidly discharged through a chimney. If insufficient flow occurs through forced ventilation change of flow direction in extracts.

Cause reverse movement of the air flow may become uneven pressure formed by connecting multiple branches to one ventilation duct. In such situations, the check valve is equipped with each line (+)

In the case of air inside the house with several air intake points may change in the flow direction in case of inclusion in one of them forced ventilation. For example, if a box of kitchen and bathroom are connected into one system, the inclusion of the cooker hood will lead to the emergence of air pressure not only in the street but also in the bathroom.

Changing the parameters of the medium outside the apartment or house can also be a cause of reverse thrust. During construction works associated with changes in terrain, such as the construction or demolition of buildings located close to, you can change the direction of the wind in the direction of stretching.

In apartment buildings, using the common bleed air conditioning vents, you may experience reverse thrust in the apartment because of the connection of powerful neighbors hoods. This problem is particularly acute for older homes, the general air ducts which are designed without taking into account the possibility of the use of devices for forced ventilation.

The capacity of the general ventilation shafts of old apartment buildings are not designed for the passage of a large volume of air generated by today's powerful extracts

Even if at the moment the conditions for the emergence of reverse thrust is not, it is better to install a check valve for installation of the system of air circulation. Possible modifications of its pollution ventilation or external factors may cause alternating the direction of air flow. The cost of the finished device is small, and the introduction of the valve into an already running air ducts is a time consuming task.

Types of embodiment of the check valve

Due to the widespread use of suction devices use a manual control to regulate the air flow passage is no longer relevant. There are essentially four different constructive method for automatically preventing reverse thrust in the ventilation system. Each of them has its pros and cons that must be considered when choosing the type of device.

Single-gravitational action

Flow directed from the room, the valve exerts pressure on the flap and opens the air passage. In the absence of movement or in case of reverse thrust pressure on the flap and will not be under the influence of gravity it closes.

The use of only one flap for air passage and use gravity to close it makes gravity valve model simple and reliable

When properly installed, the gravitational non-return valve can be employed with natural ventilation, as the resistance to opening sash it is insignificant. There are two ways of performing such a construction:

• the offset position of the axis on which the flap is attached, with respect to the mid-section of the duct channel;
• the presence of the counterweight, located inside or outside the device.

Given the fact that the closing flap principle is based on the action of gravity, it is necessary to place the valve in dependence on the design of horizontally or vertically using a level. Otherwise it may or incomplete closing it, or need to be a significant force in the flow of air ventilation system for the opening leaf, especially in the case of using a counterweight.

Installation diagram of the check valve on the vent is determined by constructional features of the system. The devices are mounted so that they open during the vane of airflow

Butterfly using springs

Check valve "butterfly" type is provided with two shutters, which are formed at an excess pressure to the desired side and snap shut by means of springs in its absence. Since the closing process is not dependent on gravity, such a device unlike gravity can be positioned at any angle.

Typically, such an option is functioning only when using forced ventilation hood. Before acquiring the sensitivity check valve shutters for opening to the air pressure characteristic of the duct on which it is installed. Some modern devices "butterfly" type can be adjusted according to the strength of a spring.

Design "butterfly" type with closing flaps under the action of springs are used in ventilation systems with strong air pressure, which is created by drawing

Shutters on the ventilation grille

The grille covering the exit to the street or in a ventilation shaft, often equipped with a valve, resembling in appearance window blinds. It works - gravity, similar to the single-wing version. The use of multiple flaps instead of one due to the compactness of the device in the open position, which is important for the external system elements.

Dimensions gratings are designed for standard parameters of ventilation ducts destined for the hoods and air outlet openings in the walls. Valve to prevent reverse thrust can be installed on all or only grate opening for natural ventilation.

On sale there are bars with a check valve other constructive solutions. However, embodiments of the membrane or the use of springs will have serious problems with operability at low temperatures. Therefore, for outdoor grille is better to choose a device with the shutter type of "blinds".

Application of the flexible membrane

The operating principle of the diaphragm of the check valve based on the flow possibilities to change the position of the flexible plate. Its placement allows for one direction of movement of air open hole for ventilation, while the other - to close it tightly adjacent to the perimeter.

For tripping the check valve membrane for opening or closing the air flow sufficiently small force, so such devices are successfully used in natural ventilation

In the case where there is a risk that a strong reverse thrust deforms the membrane must have additional stiffeners, on which it will be based at the closing of the vent holes. This fact must be considered when purchasing a diaphragm valve is otherwise possible distortion and subsequent loose Flap abutment, whereby partial transmission will occur reverse airflow device.

Especially in the independent manufacturing

Given the low cost of check valves, independent production unit is only relevant when applying the ventilation grating or air ducts with non-geometric parameters. In this case, often cheaper and faster for him to do valve than complete the transition to a standard shape and size.

The easiest way to make their own membrane or univalve valve. As used sash rigid material, such as plastic or metal plate. Particular attention should be paid to the following points:

• density abutment plate to the walls of the valve housing or a fixing protrusion to prevent the formation of the gap and the air passage;
• eliminating knock plate, which is especially important in the case of frequent change of the direction of air movement.

For the diaphragm valve can be used a sheet of heavy paper or Mylar film, a larger diameter than the vent hole. When a strong reverse-drawn in order to avoid deformation of the membrane material must install the grating on which it is based.

As membranes suitable lavsanovaja film. She does not lose its properties when exposed to moisture, as well as by repeated bending

Terms of placement and mounting

For systems of any configuration necessary to plan the placement of the valves so that the reverse thrust has been blocked on any combination of fans and hoods. The correct ventilation installation work quality depends devices themselves.

Location valve in the ventilation system

If the exhaust system has a single air intake space, which ventilation duct comes into the shaft or on the street, it is sufficient to install a single duct to prevent back draft valve.

If the topology of the system is more complex due to the presence of several hoods or openings for natural ventilation, the following rule applies to the placement of check valves:

• At each branch connecting the air intake point and the main duct, check valve is set. This is necessary to prevent the redirection of air in the exhaust side, when it is not included.
• Usually another device installed at the outlet of the ventilation system. Ideally, when the total channel integrity, this is not necessary, but experience has shown the validity of the valve assembly in this place.

Typically, the non-return valve is installed in areas with the most convenient access to them. This is due to the fact that they must be periodically cleaned of adhering dust and fat, otherwise there will be total closure flaps at the back draft.

Such a valve arrangement for the organization of forced and natural ventilation provides good access to it to perform maintenance work

In the simulation, the duct should be remembered that manufacturers can install a check valve on the fan or hood. In this case there is no need to install separate protection against reverse thrust.

Particular attention should be given to installing the valve near the mine entrance of apartment buildings. general ventilation system is protected from direct sunlight cavity with positive temperature in which humid air is fed intermittently, that is the ideal environment for the propagation of various kinds microorganisms. Also, there are often inhabited by insects, birds and rodents.

Management companies often do not perform the work in time to clean the air of public mines, which leads to a deterioration in air quality

The air in these mines rarely meet sanitary-epidemiological requirements for residential premises. Therefore, even in the case of regular sanitizing ventilation ducts need to avoid the possibility of reverse thrust and penetration of air from her apartment.

The nuances of installation and maintenance

round or rectangular ducts standard dimensions used for the creation of domestic ventilation. For them, there are ready solutions containing a check valve that can be installed anywhere in the system. In this case the mounting process will be similar to any other ventilation connection element.

Prepared solution for ventilation, organized using a plastic conduit, the valve arrangement is in the shaped element - the connector forward channels

If necessary, switch the operation of natural and mechanical ventilation, there are two types of solutions-return valve installation, allows you to make this possible:

• installation of a tee near the ventilation grille, with the installation of the valve on the strains for natural ventilation;
• acquisition lattice special design with two holes for the two types of ventilation.

Mounting such a grating can be performed via screws or nails liquid.

The first way is preferable, since parsing of the ventilation system for cleaning, repairing or changing its configuration is easiest to carry out in the first place by removing the grid. If you decide to install the grille on the inside of the premises, it must be carefully sealed joint grille and the wall.

lattice wall mounting is best accomplished with the help of screws. In this case, it is easy to remove for maintenance work on cleaning the air duct and a check valve

One of the problems located on the street gratings equipped with shutters, a freezing and icing of wings in the cold. The air coming out of the bathroom, toilet or kitchen, saturated with moisture, which freezes at low temperatures. In this case, there are two problems:

• stop flaps tightly closing the vent, whereby when air penetrates the room reverse thrust, albeit to a lesser extent than in the absence of protection;
• there is a significant reduction section hole, thereby reducing the system capacity, which reduces the air circulation and increases the load on fans and kitchen hoods.

In this connection it is necessary to periodically check for ice on the grill and removing it. The easiest way to perform this procedure by mechanical means, but there is a risk of damage to the hull and shutters, if they are made of plastic. Therefore, the outside is better to establish a rigid grating made of metal.

Useful videos on the topic

Installation of the valve in the ventilation grille in standard sizes:

Valve Fitting method for alternating operation and the forced natural ventilation:

Fabrication of the diaphragm valve:

Install a check valve in the exhaust air removal system to ensure normal ventilation functionality eliminate reverse airflow, deliver receipts from odors and toxic volatile compounds.