The deflector is a special nozzle that is installed in the upper part of the exhaust pipe and serves to protect the channel and improving the ventilation process. The effective operation of the ventilation system is largely dependent on atmospheric conditions. In winter, when the temperature difference indoors and outdoors is large, there are excellent conditions for traction inside the natural ventilation duct.
Warm "home" air rises up to the street. In summer, the situation changes radically, since temperature conditions outside the house and inside it are almost equal. This entails a significant reduction in pressure drop and traction.
Natural ventilation is noticeably worse. In addition, wind has a special effect, improving or hampering air exchange. Just installing the deflector allows you to reduce the influence of atmospheric conditionsby improving the functioning of the entire ventilation system. In addition, this technical device prevents the entry of debris, insects and birds into 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 structure. A standard nozzle consists of the following parts:
- a diffuser, which is a truncated cone;
- an umbrella protecting 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 pipe of the ventilation channel that goes to the roof. It is in this node that the pressure is rarefied due to the acceleration of air flows.
Reference! The Bernoulli effect makes itself felt here, when an increasing flow rate, provoked by a narrowing of the channel, leads to a drop in pressure. Air from the room begins to tend into the discharged space.
A protective umbrella is attached to the diffuser using racks. Thanks to the brackets, a casing that acts as a flow divider and directs the air masses to the diffuser is fixed. The efficiency of the system with a properly selected and installed deflector can increase by about 15-20%.
Ventilation deflector classification
There are several reasons to classify devices:
- by model - TsAGI, Grigorovich, Astato, a rotational ventilation turbine, a deflector in the form of the letter H and a weather vane of the type "Net" or "Hood";
- in the shape of a pommel - flat, semicircular, with an opening lid, gable, spherical;
- according to the principle of work - static and rotational;
- at the place of installation - products for the chimney, basement, for air conditioning and on the roof.
Let us consider in more detail 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 the absence of reverse thrust even in large ducts.
Grigorovich deflector consists of a conical diffuser and a reverse hood fastened in a single structure. Moreover, the narrowing of both elements is directed towards each other. Thus, a double effect is achieved, increasing the efficiency of the device.
Nozzles from the French company Astato equipped with an electric fan to enhance traction. The degree of vacuum required for the full functioning of the entire system turns out to be greater than in analogues that operate only due to wind.
Rotary turbine has a spherical cap, which is a metal drum with many blades. The fabrication material is thin and light enough to rotate the turbine even at a wind speed of 0.5 m / s. The work efficiency is 2-4 times higher than static models, however there is a significant minus of the design - it is absolutely unproductive in full calm.
Technical product in the form of the letter H in fact, it is a classic version, the productivity of which is at least doubled due to the unusual shape of the nozzle. Two deflectors, in the connection resembling the letter H, are mounted on one pipe. It is she who is attached to the ventilation shaft.
Weather vane "Hood" It is represented by a rotary cap that catches the direction of the wind and several visors hanging over one another. They serve as a diffuser and at the same time protect against precipitation. The wind, passing through the visors, receives acceleration. Thus, a rarefied space forms above the pipe, where air from the room tends.
How to make a DIY air vent
Before proceeding with the manufacture of the deflector, it is worth preparing carefully. 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 on the network) or be guided by formulas. The width of the billet of the diffuser is determined based on the inner diameter. Having learned the outer diameter of the ventilation pipe, you need to multiply it by two. Height is determined by multiplying the diameter by 1.7.
First you need to make patterns from cardboard, and then collect from it a model of the future deflector and verify the correct execution. Then, using a marker on a steel sheet (thickness within 1 mm), all the blanks are drawn.
After cutting, the assembly phase begins. The blanks are given the necessary shape, fastening is carried out using rivets or semi-automatic welding. The outer cylinder can be fastened to the inner cone, if you take a few metal strips, they will serve as brackets. Using the same strips, the protective top can be connected to the cylinder or fixed with rivets on the inner cone.
As a rule, the ventilation pipe is located about a meter above the ridge, therefore it is more advisable to mount the entire device on the groundclimbing the roof already with the finished option.
Important! Installation of the deflector is carried out at a height, so you should observe safety precautions, use insurance. It will be better if the work will be performed with an assistant.
Tips for making different types of deflectors
In order for a device aimed at improving the performance of the ventilation system to adequately cope with the tasks assigned to it, it is worth listening to some tips from experienced craftsmen. Choosing rotational models for installation in areas with snowy and cold winters is not the best option. There is a high probability of icing and snowfall in the appliance, to 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 margin of 1 cm from each edge. This will allow a high-quality and reliable connection.
With a sufficient level of skill, you can also try to make a rotational turbine yourself. However, you will need to carefully prepare the drawings and cut out a lot of uniformly shaped petals, which together will ensure the rotation of the entire installation.
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