Warm mist humidifiers use a heating element to boil the water in the humidifier and release it into the air in the form of a warm steam. If you live in a cold climate, using a warm mist humidifier will help make the room feel warmer than it actually is (as opposed to a cool mist humidifier, which can have the opposite effect). Warm mist steam humidifiers are quieter than cool mist evaporative humidifiers, because they do not use a fan. Instead, the heating element simply boils the water into a pure steam, which rises into the air free of all minerals and impurities. Any mineral content that was present in the water is left behind in the humidifier, and will not enter the room air. Mineral deposits left behind in the humidifier can be removed using vinegar. Some models also use optional mineral absorption pads, which help to absorb the mineral deposits before they can stick to the humidifier.
Pros:
Cons:
Quiet operation. No wick filters to replace. Pure, clean mineral-free moisture output. Some models have a medicine cup to disperse soothing vapors into the room.
Higher power consumption (heating element uses more electricity than other humidifiers). Most units are limited to small rooms only. May pose a burn risk for small children if the humidifier is accidentally tipped over.