Duct devices are one of the most common devices for moving clean air. They are used in everyday life, public places and various industries. In order to provide the manned room with an inflow of fresh air, it is necessary to install the duct fan correctly.
Definition of a duct fan
The devices are designed to generate a pulse that provides energy for the air flow to move in a specific direction. The connection of such a fan is usually done by embedding it into the air duct break. The parameters of the created stream depend on the internal structure of the system. The devices can operate with air masses up to 80 ° C.
The characteristics of the resulting flow can be controlled (within certain limits) by adjusting the wheel speed. The duct configuration has different air pressure values at the beginning and at the end. The device can flexibly compensate for changes caused by fluctuations in the indoor or outdoor environment of the room.
Device and principle of operation
The body of the device can be made of metal or plastic. Products made of galvanized steel are most resistant to corrosion. To improve the soundproofing qualities, the walls are made of several layers.
The design also includes the following elements:
- the impeller, on which the efficiency of the device depends;
- Electrical engine;
- a rotating impeller with blades attached to it (the latter provide the movement of air masses in a certain direction);
- thermal protection block, thanks to which the fan can operate at temperature extremes;
- lattice elements mounted on the walls and protecting the air duct from clogging.
Often, devices are also equipped with a speed controller. A capacitor can be used for starting. Some models are equipped with a non-return valve to prevent the movement of air from the street into the building. This element can depend on the sensor or close spontaneously when the flow stops.
When the wheel rotates, an area of low pressure arises, air is sucked in through the lattice parts and goes to the blade surfaces. The pressure increases and the flow moves along the air duct network in a certain direction. Overheating is prevented by thermal contacts that open the circuit when the temperature rises.
Types and design features
Before installing a duct fan, you need to decide on a model suitable for a specific task. Devices differ among themselves in a number of parameters.
By appointment
Exhaust fans carry out the exhaust air mass to the outside. On the other hand, supply air supplies provide fresh air. Reversible models do both. This is achieved by changing the direction of travel of the rotor device and the impeller.
Appliances intended for domestic use have low power and are able to serve limited space. Fans designed for industry are very powerful and often oversized.Some of them generate a lot of noise when turned on.
By form
The shape of the product depends on the section of the air duct where it is planned to be mounted. Round cut pipe models are the most popular. Less common are rectangular devices. The least common type is square-shaped fans. They have the highest resistance value.
By design
Axial models consist of a cylindrical body, an engine and blades attached to its axis. These are not very powerful products intended for use in everyday life. They usually make almost no noise during operation. Installation of such a duct fan is easily done at home.
In devices with radial air movement, it is thrown away by the centrifugal force arising from the twisting of the vane mechanism. Due to its compactness, installation of the fan into the air duct is straightforward. When the blades are directed backwards, the power decreases, but also less noise is generated and the energy consumption from the mains is reduced.
Diagonal structures combine axial and radial movement of air masses, which ensures their high efficiency. Moreover, such models are small in size and emit little noise. The scope of these devices is wide.
Tangential instruments are used in some industrial installations. The air flow in them moves along the perimeter of the wheel.
A young development can be called centrifugal models, which have sufficient power with small dimensions and low noise generation.
By operating conditions
Most fans are designed to function in a natural environment, but there are also special models for special conditions. For example, devices designed for fire hazardous conditions are made from materials that do not deform at high temperatures. Special models are produced for industries working with explosive compounds, as well as for air with high dust content. There are also devices with increased heat resistance - such a fan can be connected in a bath or sauna to remove excess steam. They are also used in industry when working with stove and fireplace units. Ventilation units can be manually or automatically controlled.
Advantages and disadvantages
The devices are attractive for their ease of installation and wide range of applications. Most of them work quietly. They do not require special maintenance - it is enough to wipe the body and blades from dust once every few months. The electric motor is protected from voltage surges, which minimizes the likelihood of failure.
The disadvantage of the fans is the lack of an air filtration option. If there is a need for it, it is advisable to install other devices, for example, air cleaners.
Application area
Duct fans are used in households, in commercial premises (shops, catering establishments and others). For narrow industrial purposes, models with special properties are designed. Models are available to suit high humidity conditions such as bathrooms and toilets. The hood can be mounted so that it turns on simultaneously with the lighting. One of the supply conductors is opened and connected to the switch. If the latter has two buttons, they do it differently: one of them is connected to a lighting device, the other to a ventilation one.
Duct fan installation
Before connecting a duct fan, you need to study the diagram recommended by the manufacturer on the package. For home use, it is easiest to install the device in the air duct inlet. Dimensions are selected based on the cross-section of the duct pipe. Home appliances are 9-30 cm in diameter.
The axial device is fixed with brackets to a wall or ceiling hole. It is connected to the air duct by means of branch pipes. The cracks are closed with a sealing compound. A grid is attached to the beginning of the air duct to prevent clogging. The installed device is connected to the network.
Duct fans are adapted for continuous operation and do not need complicated maintenance. Low weight allows you to mount the device on your own.
