A humidifier releases water vapor into the air from an internal reservoir, dispersing it through various means. Warm mist humidifiers boil water to produce steam, while cool mist humidifiers rely on physical means to spray tiny droplets into the air. Ultrasonic models use vibrations to vaporize water into the home.
Under normal circumstances, home humidity should vary between 30 and 50 percent, depending on the season. Air conditioners and heaters can alter the humidity levels in the home, drying out the air to the point where mucous membranes become irritated and inflamed. This can exacerbate colds and other respiratory issues. A humidifier may not cure these conditions, but it can help sufferers breathe easier.
A whole-house humidifier connects to the furnace or HVAC system to improve the humidity of the entire home at once. Since these devices are active 24 hours a day, they often rely simply on evaporation to release water vapor into the air. No matter the size, humidifiers require regular refilling in order to continue providing moisture.
Overuse of a humidifier can cause condensation and even water damage in the home, and encourage mold and bacterial growth. In addition, the interior of a humidifier can be a breeding ground for micro-organisms if the device is not regularly cleaned and dried.