Humidifiers.(Home and Yard: Reap the Savings)(Buyers guide)

Who needs a humidifier? Anyone who has uncomfortably dry or itchy eyes, throat, or skin, or whose asthma is a problem indoors during the heating season. While indoor relative humidity should be 30 to 50 percent, it can drop significantly in winter, since cold air holds less moisture and dries as it's heated.

Humidifiers have improved over earlier models that spewed white dust in our tests. But that doesn't mean they all work equally well. Our tests show that manufacturer claims can be a poor guide to performance. Indeed, several small tabletop models fell well short of their claimed output and may not raise humidity as high as you'd like.

WHAT'S AVAILABLE

Holmes, Honeywell, Hunter, Kaz, and Reli-On (Wal-Mart) are the major brands. Others include Bemis, Bionaire, Emerson, La-lo, Sears, and Sunbeam. Humidifiers come three basic ways:

Tabletop. These cost the least and are fine for one room. Types include evaporative models, which use a fan to blow air over a wet wick, and warm-mist models, which use a heating unit to boil water before cooling the steam. Small tanks need to be refilled frequently, however. Evaporative models are noisy, and warm-mist models cost more to run. Price: $20 to $100.

Console. These models have large, powerful fans that rapidly blow air across water, generating large volumes of moist air. That is why they are better for multiple rooms. Console models are also efficient and can be placed unobtrusively. But all use evaporative technology and are relatively noisy. And the larger the tank, the harder it is to handle. Price: $80 to $140.

In-duct. These whole-house humidifiers are convenient, quiet, and efficient, making them least expensive to operate. Most are evaporative-bypass units, which tap into the air supply and return ducts. Some are warm-mist while others are nebulizers, which use a spray technology. Nebulizers can result in white dust, however. What's more, in-duct humidifiers require forced-air heat, cost the most and often require professional installation. Price: $100 to $300, plus $100 to $200 to install.