Humidifier types and styles

If the atmosphere in your house is drying out your throat, nasal passages and skin, a humidifier can do you a world of good. Humidifiers are particularly helpful in the winter, when the air naturally holds less moisture. Even wood furniture, floors and structural beams can begin to dry out and crack as a result of excessively dry air. A bit more humidity, particularly warm mist, can also help you control heating costs by making the air feel warmer.

There are four types of humidifiers, each with its own advantages and drawbacks:

  • Evaporative humidifiers work by soaking water up into a wick and blowing the moisture out with a fan. Most console humidifiers are of this type. Smaller evaporative humidifiers are generally inexpensive, and their filters help keep microorganisms and minerals in the water from being dispersed into the air. However, the units must still be cleaned regularly and the filters changed on schedule.
  • Impeller models, sometimes called cool-mist humidifiers, use a spinning disk to disperse water droplets into the air. Along with the water, they can spread microorganisms and dissolved minerals, which settle as white dust onto your furnishings. To prevent this, experts recommend filling them with distilled or demineralized water, which adds considerably to the operating cost of the humidifier. Because of this problem, we didn't include impeller humidifiers in this report.
  • Ultrasonic humidifiers are also sometimes labeled as cool-mist humidifiers, but they produce a mist by using high-frequency sound vibrations to drive water into the air. This type of humidifier is very quiet, because it doesn't use a fan to evaporate water. Most ultrasonic models don't use a filter, although they may include a demineralization cartridge that needs to be replaced every few weeks. This cartridge helps prevent white dust, but it isn't 100 percent effective.
  • Warm-mist humidifiers tend to be the least expensive. They work by boiling water to produce steam, which is then cooled slightly before being released. ConsumerReports.org notes that warm-mist tabletop units are quieter than evaporative models, but they also tend to use more energy. Warm-mist humidifiers can also raise the air temperature in a room -- handy for the winter season, but not so useful if you live in a warm climate. Warm-mist humidifiers are not recommended for homes with small children because the heated water can cause accidental scalding. They should also be avoided if anyone in the household has asthma, because warm mist can irritate breathing passages.

Humidifier shopping tips

More humidity isn't always better, which is why experts say it's important to get a humidifier you can set at the appropriate level (generally between 30 and 50 percent). Signs that an area is over-humidified include peeling paint and condensation on the interior window surfaces. Too much humidity can promote the growth of mold, bacteria and dust mites.

Here are some other factors you'll want to consider before purchasing a humidifier:

  • Match the stated output of the humidifier to the area you want covered. Output is measured in gallons; for example, a 3-gallon humidifier can put out 3 gallons of moisture per day. The specs for the humidifier should also say how big an area it can cover.
  • Pay attention to the size of the tank. Although a 3-gallon humidifier will humidify a large area, you'll have to refill it frequently if it has only a 1-gallon tank.
  • Look for an adjustable humidistat. This control measures the humidity in the room and adjusts the output of the humidifier to maintain a set value.
  • Note the alert features. Indicator lights alert the user when water is low or the filter requires maintenance. Even better, an automatic shutoff prevents the humidifier from running when the reservoir is dry.
  • Make cleaning a breeze -- choose a model with a removable reservoir. Other helpful features include a wide mouth, a carrying handle and a tank that will fit under your faucet.
  • Purchase a demineralization cartridge if you have an impeller or ultrasonic humidifier. These minimize dust caused by the minerals left behind by tap water and are a must if you have hard water. Some models come with a demineralization cartridge; in other cases, it's an optional add-on. Remember to replace the cartridge as scheduled.
  • Consider antibacterial features. These include antibacterial filters, ultraviolet light and antibacterial plastic used in construction.

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