There are several technological options to choose from today to humidify the indoor air.
NATURAL EVAPORATION
This method is based on the natural principle of water evaporation in nature. The water sticks to the surface of the rotating disks or soaks into the filter paper and rises upwards. The fan is used to direct the flow of dry air through these filters. This makes the water evaporate into the air faster and easier. It is not possible to saturate the air with water vapour by cold evaporation. Unlike other principles (ultrasound, thermal evaporation), no emitted steam is visible with this method of humidification.
A special category in natural evaporation is air washers. These are a combination of a purifier and a humidifier operating on a principle similar to cold evaporation. Special evaporator discs absorb (bind) water, while the fan blows dry air through these humidified rotating discs. The humidified air is then dispersed into the surroundings. Humidifiers working on this principle are high-performance devices that have low operating costs and are almost silent. A significant advantage of these devices is the fact that they clean the air from hazardous particles in the air and, if equipped with other technologies for air purification (e.g. PLASMA system nebo HEPA filter), they can be a full-fledged air purifier replacement.
ULTRASOUND
The vibrating membrane (piezo) uses ultrasonic technology to decompose the water into micro droplets, which are then dispersed into the air by means of a fan, where they evaporate. The visible steam is cold and harmless to health. Ultrasound devices do not require as much electrical energy and have sufficient power. When water vapour is generated by ultrasound, minerals are also released into the air, so it is necessary for devices with this technology to be equipped with water filters. Even in the case of hard water, this principle can lead to the deposition of mineral dust on the furniture and other equipment in the room.
HEAT EVAPORATION
The water inside the appliance heats up until water vapour is generated without bacterial germs (they are destroyed by high temperatures). The steam spreads in all directions in the room and increases the relative humidity of the air very effectively. These humidifiers are highly productive and should therefore always be equipped with a hydrostat for humidity control. But when it comes to security, it's worse. There is really hot steam coming out of the device, and therefore these devices are not suitable for places where children or animals are present. In addition, the heating elements become clogged with lime scale over time, and regular maintenance is required.