How to choose a fan for a forced ventilation system of a

In order to properly equip in your own home a system of forced-air ventilation with forced air circulation, you first need to choose the most suitable axial, centrifugal or duct fan for all necessary parameters, which is the most important operating mechanism of this system.

When choosing this device, you need to take into account a large number of various external factors, such as: the total volume of the ventilated residential space, the shape, material and cross-sectional area of ​​the air duct, the minimum and maximum temperature of the atmospheric air, the total length of the ventilation system, and some other indicators.

Overview of domestic fans

In order to help the reader choose the most appropriate option for himself, this article will provide a description of various types of electric fans designed for use in domestic ventilation systems, as well as their main characteristics and a brief overview of the main advantages and disadvantages of a particular model.

At the same time, this article may be regarded as a complete instruction for choosing an exhaust or blower fan for a home ventilation system with forced air circulation.

Purpose and main functions

The normal functioning of a domestic ventilation system with natural air circulation becomes possible, due to a slight drop in atmospheric pressure in the area between the inlet of the air supply duct and the outlet of the exhaust duct.

At the same time for the normal operation of such systems, the following conditions must be met simultaneously:

1. To provide the necessary difference in atmospheric pressure and, accordingly, the natural thrust in the system, it is necessary that the outlet is located at a height of at least 4 meters above, relative to the level of the inlet.
2. To ensure the necessary capacity, at low air velocity, it is necessary to use air ducts of large cross section.
3. The cross-sectional shape of the ventilation ducts should be as close as possible to the circumference, and their inner surface should be uniform and smooth so as not to create turbulent airflow turbulence.

When an electric fan is included in the ventilation system circuit, the observance of the above conditions is not necessary for the following reasons:

1. The difference in air pressure between the discharge and exhaust paths is provided by the operation of the fan impeller, therefore, the height difference in this case has no fundamental significance.
2. In forced ventilation systems, the speed of the air flow is significantly higher, so air ducts of even a small section have a higher throughput.
3. Injection or exhaust fans make it possible to create a higher pressure drop in the system than in the case of natural air traction; therefore, the resistance of the internal surfaces and turbulent twists can be neglected in most cases.

Note! The maximum air velocity in natural ventilation systems is 1 m / s, while in systems with forced air injection or pumping out of air, its flow can move at a speed of at least 3 m / s.

Varieties of household fans

Almost all domestic fans are driven by an electric motor, but many models differ in engine power, speed, performance, maximum working pressure, type of impeller used, air supply, size, weight, and many other technical parameters.

Based on the principle of air supply and the type of impeller used, all existing models can be divided into several types.

1. The simplest, but at the same time the most common models that are most often used in everyday life, are axial electric fans.

1. Models with a centrifugal air injection circuit, which are capable of creating higher pressure, and developing a greater speed of movement of the air flow are considered more productive.
2. One of the varieties of such models is a system with a diametrical arrangement of the blades, but due to the cumbersome design, it is practically not used in everyday life.
3. For installation inside duct used duct fans, which are small in size and relatively low noise level.

Axial fans

An axial, or in other words, axial fan was given this name because during its operation the direction of movement of the air flow is located on the same axis with the plane of the working impeller.

This scheme is widely used in household ventilation systems, due to the fact that it has the following advantages:

1. Electric motors Such devices, as a rule, have low power consumption, therefore, are quite economical, and can work for a long time without stopping.
2. Axial household fans not able to develop high pressure, but at the same time their power is enough to constantly change the entire volume of air in the room. This mode of operation allows you to ensure uniform air exchange throughout the entire time of operation, and at the same time allows you to get rid of smoke and unpleasant smell, as well as to avoid the occurrence of drafts.
3. Axial injection circuit air has the simplest design, which is a straight-through air channel with an impeller located in it and a driving electric motor, therefore the price of such devices is significantly lower than the cost of other more complex models.

Tip! Another advantage of axial fans is the lowest noise level, among other similar devices, so they are most often used as exhaust hoods for ventilation of the kitchen, bath, bathroom, bathroom, and other domestic premises.

Exhaust and pressure fans centrifugal type

For the operation of complex ventilation systems with a large number of air ducts and various auxiliary devices, as well as with a large length of the main injection and exhaust air ducts, high-performance industrial fans are required, capable of moving a large volume of air masses in a short time.

Most often, to solve such problems, devices with a centrifugal system for moving air are used, the principle of operation of which is as follows:

1. The working body of the machine is an external metal casing of stainless or galvanized steel, inside of which a rotating drum is mounted on ball bearings.
2. The walls of the drum contain a large number of radially mounted blades that during rotation rotate the air flow, thus giving it a rotational motion.
3. As a result of rotation, under the action of centrifugal force, air particles are thrown from the center of the rotating drum to the inner side of the metal casing, after which, compressing in a closed space, they are directed to the outlet of the discharge path.

Industrial radial fans, as a rule, are driven by powerful electric motors that operate in a constant or cyclic mode, and are activated manually or when the sensors of the automatic climate control system are triggered.

Note! Centrifugal electric fans can work equally efficiently both for supplying and not for removing air, therefore, depending on the type of connection, they can be used in systems of both supply and exhaust forced ventilation.

Duct fans

Channel devices are primarily intended for installation inside an air duct, as well as in the rupture of a main line supplying or venting air as an independent or auxiliary operating mechanism of supply and exhaust ventilation.

Among the main distinguishing features of duct fans are the following performance features:

1. Most often, they are manufactured according to the axial scheme, therefore they are distinguished by their compact size and low noise level.
2. Such devices can easily be installed with their own hands both in the designed and in the existing domestic ventilation systems.
3. Currently, there is a large selection of different models that differ in size, shape, performance, and other technical parameters, so choosing the right device will not be difficult.

Tip! Even when installed indoors, preference should be given to devices made of plastic, stainless steel or other corrosion-resistant materials, since water vapor is always present in the atmospheric air, and ventilation and air-conditioning systems have an increased tendency to condensation.

Multizone devices

In a centralized smoke removal system, as well as in a ventilation and air conditioning system in a private residential house, it is convenient to use a multi-zone device, which is a high-performance centrifugal fan installed in a technical room, for example, in a basement or in an attic.

Its main feature is that on its casing there are several connecting flanges for connecting exhaust or discharge air ducts, each of which can independently serve various residential or utility rooms.

Thus, one device can fully ensure the operation of the system of supply and exhaust ventilation of the entire apartment building.

Tips and tricks

In order to make the right choice of domestic fan, depending on its purpose and the implementation of specific tasks, the following rules should be followed:

1. For effective ventilation of bathrooms and sanitary facilities, it is necessary to select an axial-type device with a nominal capacity of at least 30 m? / Hour.
2. For installation in rooms with high humidity, for example in the shower or in the bath, you need to ensure that the level of protection was not lower than IP.

1. It is easy to determine the optimum performance of a kitchen hood by multiplying its total volume by 10. For example, a kitchen size of 4 x 3 m with a ceiling height of 2.8 m will be 33.6 m ?, respectively, the performance of an exhaust fan must be at least 330 m ?/hour.
2. The exhaust air capacity for residential premises is determined according to a similar scheme, but in this case, the total volume of the room should be multiplied not by 10, but by 3.
3. If necessary, quickly heat the room, you can use electric fan heaters for the house, in which an electric heating element is installed in front of the impeller of the air blower.

Tip! In order to prevent undesirable entry of cooled atmospheric air from the street into the room, all household fans should be equipped with a check valve.

Conclusion

After reading this article, we can conclude that the best option for kitchen, bathroom and toilet, as well as for residential premises of an apartment or a small private house is a conventional axial fan, which is installed in the window opening of the window or in the ventilation grille of a common vertical riser.

To get a visual idea of ​​how to do it yourself, you can watch the video in this article or read similar materials on our website.