Ventilation deflector - device and principle of operation, classification

The deflector is a special nozzle that is installed in the upper part of the chimney and serves to protect the duct and improving the ventilation process. The efficient operation of the ventilation system largely depends on the atmospheric conditions. In winter, when the temperature difference between indoor and outdoor is large, there are excellent conditions for draft inside the natural ventilation duct.

Warm "home" air tends upward into the street. In the summer, the situation changes radically, since the temperature regimes outside and inside the house are practically equalized. This entails a significant reduction in pressure drop and thrust.

Natural ventilation is noticeably impaired. In addition, the wind also has a special effect, improving or hindering air exchange. Just installing the deflector allows you to reduce the influence of atmospheric conditions.improving the functioning of the entire ventilation system. Plus, this technical device prevents debris, insects and birds from entering the mine. The material for the manufacture can be metal or plastic.

Device and principle of operation

To understand how a deflector works, you need to have an idea of ​​its design. A standard nozzle consists of the following parts:

• diffuser, which is a truncated cone;
• an umbrella that protects the channel from all kinds of debris;
• housing in the form of a cylinder, connected to the diffuser using brackets.

The truncated cone with its lower part is put on the ventilation duct pipe that goes out to the roof. It is in this node that the pressure is rarefied due to the acceleration of air flows.

Reference! Here the Bernoulli effect makes itself felt, when the increasing flow rate, provoked by the narrowing of the channel, leads to a drop in pressure. Air from the room begins to rush into the discharged space.

The protective umbrella is fixed to the diffuser using the stands. Thanks to the brackets, the housing is fixed, which acts as a flow divider and directs the air masses to the diffuser. The efficiency of the system with a properly selected and installed deflector can increase by about 15–20%.

Ventilation deflector classification

Devices can be classified on several grounds:

• by models - "TsAGI", Grigorovich, Astato, a rotary ventilation turbine, a deflector in the form of the letter H and a weather vane of the "Sachok" or "Hood" type;
• by the shape of the pommel - flat, semicircular, with an opening lid, gable, spherical;
• according to the principle of work - static and rotary;
• at the place of installation - products for the chimney, basement, for the air conditioner and for the roof.

Let's take a closer look at the most popular options that have proven themselves in business.

TsAGI model named after the place of development - the Central Institute of Aerohydrodynamics. It is a classic version of a conical nozzle with a protective cover placed inside a cylindrical screen. The latter ensures that there is no back draft even in large air ducts.

Deflector Grigorovich Consists of a conical diffuser and a return hood, bonded into a single structure. Moreover, the narrowing of both elements is directed towards each other. Thus, a double effect is achieved that increases the efficiency of the device.

Nozzles from the French company Astato equipped with an electric fan to increase traction. The degree of vacuum required for the full functioning of the entire system turns out to be greater than in analogues operating only due to the wind.

Rotary turbine has a spherical cap, which is a metal drum with many blades. The material of manufacture is thin and light enough that the turbine rotates even at a wind speed of 0.5 m / s. The efficiency of work is 2–4 times higher than that of static models, but there is a significant disadvantage of the design - it is absolutely unproductive in complete calm.

Technical product in the form of the letter H in fact, it is a classic version, the performance of which is at least doubled due to the unusual shape of the nozzle. Two deflectors, in conjunction resembling the letter H, are mounted on one pipe. It is she who is attached to the ventilation shaft.

Weathervane "Hood" represented by a swivel hood that catches the direction of the wind and several canopies hanging over each other. They act as a diffuser and at the same time protect against precipitation. The wind, passing through the visors, gets accelerated. Thus, a rarefied space is formed above the pipe, where air from the room tends.

How to make a ventilation deflector with your own hands

Before you start making a deflector, you should carefully prepare. To do this, you need to complete the drawings, select the material and prepare the tool. The dimensions of the future product can be taken from the table (it is easy to find it on the net) or be guided by formulas. The width of the diffuser blank is determined based on the inner diameter. Having learned the outer diameter of the ventilation pipe, it is necessary to multiply it by two. The height is determined by multiplying the diameter by 1.7.

First, you need to make patterns from cardboard, then assemble a model of the future deflector from it and check the correctness of execution. Further, using a marker on a steel sheet (thickness within 1 mm), all the blanks are drawn.

After cutting, the assembly stage begins. The blanks are given the required shape, fastening is carried out using rivets or semi-automatic welding. The outer cylinder can be fastened to the inner cone, if you take several metal strips, they will act as brackets. The protective cap can be connected to the cylinder using the same strips or fixed on the inner cone with rivets.

As a rule, the ventilation pipe is located about a meter above the ridge, so it is more advisable to mount the entire device on the ground.climbing to the roof with a ready-made option.

Important! The installation of the deflector is carried out at a height, therefore, precautions should be taken, use insurance. It will be better if the work is done with an assistant.

Tips for making different types of deflectors

So that a device aimed at improving the performance of a ventilation system is adequately coped with the tasks assigned to him, it is worth listening to some advice from experienced masters. Choosing rotary models for installation in areas with snowy and cold winters is not the best option. There is a high probability of icing and snow covering the device, so that it will negate all its functionality.

The picture shows a turbo deflector.

When preparing a drawing of a particular model for parts, you need to take a stock of 1 cm from each edge. This will allow you to make a high-quality and reliable connection.

You can also try to make a rotary turbine yourself with a sufficient level of skill. However, it will be necessary to carefully prepare the drawings and cut out many petals of the same shape, which together will ensure the rotation of the entire installation.