The surface of the room, the dimensions of the device, the functions or the capacity,... There are several criteria that will influence your final choice.
Money for value
The first criterion that needs to be taken into account is the price. It is determined in function of the capacity and the available features, and it guarantees the quality and the origins of the device.
Capacity and air flow
The most important characteristic is the capacity of the device, that determines the amount of the circulated air. The capacity is expressed in watt (from 30 to 90 watt, depending on the model), and the air flow is expressed in m³/h or m³/min.
For use at home, you can put the ventilator on a desk or on a table, with a low air flow (900 m³/h), while it is better to choose for a more powerful model with an air flow rate of 10 times higher, when it is necessary to refresh a complete room. In a professional context, the air flow must sometimes reach up to 18000 m³/h and you need to search for a model for large surfaces.
Diameter of the propellers
The ventilated surface is determined by the diameter of the propellers: the larger the propeller, the more efficient the ventilation will be, even from a distance.
Sound
Although few attention is paid in a garage or in a hangar to the presence of a ventilator, this criterion can be very important in an office or in a bedroom. The sound is measured in decibels and it depends on the speed of the ventilator (the higher the position, the more sound it makes).
Multidirectional blowing
Most of the devices are nowadays equipped with this function, as it spreads the air stream over a large surface, without needing to move the device. Certain column ventilators can even rotate over 360°, in order to serve the complete room.
Speed levels
A ventilator is equipped with several speed levels, in order to adjust it to your needs. Watch out: the faster the ventilator rotates, the more sound it makes.
Programming, remote control and functions
Similar to a lot of other devices, ventilators are nowadays equipped with programmable functions (e.g. timer, delayed start and sleeping mode) and a remote control. When you manage the functions from a distance and you program the operating conditions, you can save a lot of energy.
Several manufacturers offer new functions for a more comfortable use (functions for hot air or a breeze, with repellent effect against mosquitoes or with the distribution of an odor), or for a better health (distribution of essential oils or negative ions).
Design
The design is particularly important when you want to install the ventilator in an office or in a living room. Efficiency and aesthetics go lately hand in hand, and the devices are often available in several colors, materials or shapes.