In the room in which people are located, you need the right microclimate. Continuous air circulation can be ensured by installing a ventilation system. The efficiency of ventilation depends on the internal draft. To protect the ventilation duct from debris, which will lead to a malfunction, it is necessary to install a ventilation deflector on the duct.
The main tasks of the deflector
The natural ventilation system is dependent on atmospheric conditions. They determine its effectiveness. Due to the temperature difference inside and outside, the air flow rises. Thus, circulation occurs.
The wind is able to make adjustments to the functioning of the ventilation system. The movement of air masses under the influence of wind can accelerate or move with difficulty.
It is possible to reduce the influence of atmospheric phenomena on the operation of ventilation using a duct deflector. This is a device that looks like a cap. It is installed at the very top of the exhaust duct.
A deflector is a device that is recognized to solve several important problems:
- Protects the mine from various debris, which degrades the system and creates a fire hazard.
- Minimizes the negative impact of precipitation on equipment.
- Prevents the appearance of reverse thrust.
After installing the exhaust deflector, the efficiency of the ventilation system increases by more than 20%. In addition, the device acts as a spark arrester.
Device and principle of operation
To understand how a ventilation deflector works, you need to imagine its device. It consists of the following elements:
- A diffuser is a base that looks like a truncated cone. The lower part of the flask is put on the ventilation duct, which is discharged through the roof. The diffuser is designed to slow down the air flow and create increased pressure.
- An umbrella is attached to the diffuser using racks. This is a protective cap that prevents the ventilation duct from entering debris.
- The case, which is a ring.
You can find modifications that are equipped with special nets for catching small debris. But such an insert can make traction weaker.
The ventilation deflector works according to the following principle:
- The device picks up airflow.
- Air passes into the diffuser, where it branches and reduces the pressure in the upper part of the ventilation duct.
- A discharged void forms, into which air enters from the room after working out.
If the deflector on the ventilation pipe is correctly selected and mounted, the pressure difference at the end of the exhaust duct will increase, and the air exchange intensity will increase.
Varieties of deflectors
Devices are presented in various design features. The deflector can be closed and open type, round or square, with several umbrellas in the form of a cone or with one cap.
TsAGI design
One of the varieties of the exhaust hood is TsAGI design. It is a cap that is designed to enhance traction using air pressure and the difference in pressure.
The nozzle is equipped with an additional cylindrical screen. Inside is a traditional deflector.
Distinctive features of this design:
- Depending on the shape of the neck of the shaft, the connection to the duct can be nipple, flanged and retained.
- The ability to move air from a non-aggressive environment. Steel models are able to withstand temperatures up to +800 degrees.
- In frosts, ice may appear inside the cylinder. Because of it, the section will be blocked.
In calm weather, the deflector creates traction resistance.
Grigorovich Model
Grigorovich’s device is one of the most common models that are very popular. This is due to its simplicity and accessibility. The model consists of several umbrellas that are connected into one element.
The nozzle-cap is installed on a pipeline with a circular cross-section or mounted on top of a shaft. The air flow rate under the cone below increases due to the narrowing of the channel section. This leads to an increase in pressure difference.
Astato-style open plate design
This device is designed in France. It is designed to enhance traction of the exhaust flow of the natural ventilation system. This happens with the help of wind and fan. The nozzle can be installed on houses of any complexity and number of storeys.
Structures like Astato are made of aluminum. The model range is presented in six sizes, starting with a diameter of 16 cm, ending with 50 cm. You can control the device manually or automatically, using a pressure sensor.
Rotational models
This type of deflector consists of a turbine head that rotates, and a fixed base. The elements of the hood are made of thin material. Thanks to this, the drum with blades begins to spin even with a weak wind.
Rotary devices have several advantages:
- operating efficiency is several times higher than static structures;
- the model will protect the room in hot weather from strong heat, due to this it will be possible to reduce the cost of operating the air conditioner;
- the head of the device may look like a spherical cap, which provides a pleasant aesthetic appearance;
- reduces the risk of condensation inside the roof.
Rotary air deflector can significantly save electricity, works without the use of electricity. But this is also its drawback - if the weather is calm, it will not work.
H-shaped models
Deflectors of the shape of the letter H are intended for installation in industrial enterprises. They should increase traction in the chimney and ventilation.
When installing the structure, a visor is not required, since the upper part is closed by a horizontal element.
H-shaped devices have the main advantage - they work effectively with strong gusts of wind.
Wind deflectors
This is a deflector on the ventilation pipe, resembling a butterfly net in appearance. It has a semicircular shape. The device is mounted on a rod and rotates under the influence of air. At the top is a weather vane that rotates in the air direction.
The principle of operation of such a deflector is as follows:
- The weather vane turns under the pressure of the air masses.
- Air passes through a curved visor.
- Streams change direction and air rises upward.
- The speed of movement of air masses increases, the pressure begins to decrease. Due to this, a vacuum occurs.
The weather vane deflector is difficult to make on its own compared to static models.
Advantages and disadvantages
Ventilation deflector to increase traction effectively protects the ventilation system from dirt and precipitation.If the deflector was calculated correctly, the ventilation efficiency increases by 20%.
If the area has weak winds, it is best to install a device on the system to enhance the exhaust and air flow. In this case, the effect of tipping over the thrust will be completely eliminated.
The device has a number of disadvantages:
- If the wind direction is vertical, the flow will come into contact with the upper part of the structure. This will lead to the fact that the air will not be able to properly exit to the street.
- In winter, ice forms on the base of the pipe. To avoid problems of the functioning of ventilation, regular preventive examinations should be arranged regularly.
To combat the first drawback, designs were invented that are equipped with two cones.
Installation Rules
Before you start installing the deflector, it is recommended to study the rules and norms of SNiP. Particular attention should be paid to the height of the ventilation pipe and hood. First you need to make a drawing so that all calculations are done correctly. Dimensions should be as follows:
- 500 mm above the ridge of the roof, while the duct should be removed 1.5 meters from the top of the roof;
- if the distance from the ventilation duct to the parapet is 1.5 meters or more, the installation should be on a par with the ridge;
- when the pipe is removed to a distance of more than three meters, the device is placed near the deviation line at an angle of 10 degrees from the ridge down.
If the roof is flat, the deflector is installed at a height of 50 cm.
Before mounting the ventilation shaft near the chimney, you must correctly calculate the same height of all air ducts. If this requirement is not taken into account, smoke and combustion products will enter the house.
There are several installation nuances to consider:
- Do not mount the device in the aerodynamic area of neighboring buildings.
- The deflector must be installed in the area of free airflow. It is best if the hood is the highest point on the roof.
If a round nozzle needs to be installed on a square duct, an adapter must be used for this.
Features of choice
There are many varieties of wind devices. They are divided into groups depending on the structure and principle of operation. When choosing a suitable model, it is recommended to pay attention to the following nuances:
- construction material;
- principle of operation;
- individual device features.
Production material
Most often, wind nozzles make them stainless steel, plastic, galvanized steel, aluminum. The simplest models can be made independently. The most practical are aluminum and galvanized steel structures. Of copper, such products can rarely be found, since their cost is quite high. Only base constructions are made of plastic, since the material is very fragile. The deflector designed for the chimney is made of metal.
Functional classification
Varieties according to the principle of operation of nozzles:
- Static - the simplest designs that you can assemble yourself. They are installed on ventilation ducts in high-rise buildings and small enterprises.
- Turbo deflectors - designs of rotating blades. The base is completely static, and the head rotates.
- Weather vane mounted on the shaft of the ventilation duct. It rotates in accordance with the direction of the wind.
Thanks to the installation of the deflector, it is possible to secure and extend the life of the ventilation system, as well as improve its operation.
