portable humidifier

portable humidifier
"Portable" humidifiers range in size from small table-top units to large floor-standing units. Water is usually supplied on a daily or periodic basis via a hand-filled unit.

evaporative humidifier
The most common types of portable humidifiers, "evaporative," "cool mist," or "wick humidifiers," consist of just a few basic parts: a water reservoir, a wick, and a fan.
The wick is made of a porous material that draws moisture from the reservoir and provides a greater surface area for it to evaporate. The fan is placed close to the wick and blows air over the wick to help the water evaporate. The evaporation of the wick depends on the relative humidity. A room with low humidity has a higher rate of evaporation than a room with high humidity. Therefore, this humidifier is partially self-regulating; as the humidity in the room increases, the water vapor output will naturally decrease.
If not completely dried between fillings, these wicks will become moldy and become saturated with mineral deposits over time. They often need to be flushed or replaced; if this doesn't happen, air can't get through them, the humidifier stops humidifying the area it's in, and the water in the tank stays at the same level.
natural humidifier
An evaporative humidifier uses only a reservoir and wick. Sometimes called "natural humidifiers," these are usually non-commercial devices that can be assembled for low or no cost. A natural humidifier uses a stainless steel bowl partially filled with water and covered with a towel. Waterproof weights are used to sink the towel into the center of the bowl. No fan is required as the water is diffused through the towel by capillary action and the surface area of the towel is large enough to evaporate quickly. The stainless steel bowl is easier to clean than typical humidifier tanks. This, combined with daily or every other day changing of towels and regular washing, can keep mold and bacteria issues under control.
Indoor plants can also act as natural humidifiers because they evaporate moisture into the air through transpiration. Care must still be taken to prevent excessive growth of bacteria or mold in the soil, or spread into the air.

Vaporizers (steam humidifiers) (warm mist humidifiers)
Vaporizers (steam humidifiers, warm mist humidifiers) heat or boil water, releasing steam and moisture into the air. Medicated inhalers can also be added to the vapor to help reduce coughing. Vaporizers may be healthier than cool-mist humidifiers because the steam is less likely to carry mineral impurities or microorganisms from the standing water in the reservoir. [1] However, boiling water requires more energy than other techniques. The heat source in a poorly designed humidifier can overheat, causing the product to melt, leak and start a fire.