Humidifiers: Indoor comfort

	WINTER AIR CONDITIONING Using a humidifier can help ease dry skin and other problems associated with dry air, but you must clean it regularly.

Choosing a humidifier involves trade-offs among efficiency, cost, noise, and convenience. Our tests also show that you can't tell how well a humidifier will work based on claims.

Who needs a humidifier? Anyone who suffers from uncomfortably dry or itchy eyes, throat, or skin, or whose asthma is a problem indoors during the heating season. Ideally, the indoor humidity should be 30 to 50 percent. In winter, however, that level can drop to 10 percent. That's because cooler air holds less moisture to begin with; when heated, its relative humidity drops even more.

Don't buy a humidifier, however, if you can't commit to cleaning and disinfecting it regularly, lest you end up with more problems from mold and mildew than you started with from dry air. (See Cleaning your humidifier.)

Humidifiers are better than in years past, when some models spewed white dust in our tests. But that does not mean they're all the same or work equally well.

New features. To make filling easier, manufacturers have added handles to the tanks and shaped them to fit underneath faucets. Nevertheless, portable humidifiers are somewhat cumbersome to fill and a pain to clean. (Another type, in-duct humidifiers, are plumbed into the water supply and drainpipes, so they don't need to be filled. Changing the filter, done once or twice a year, is simple.)

Some portable humidifiers can be programmed to turn on before you get home, so that your room will be at the right humidity when you arrive. But this convenience poses a problem: Water that just sits in the tank for hours can become a breeding ground for microbes if the humidifier isn't dried completely between uses.

Claims vs. reality. Several small tabletop models in our tests fell short of their claimed output, some models by 25 percent. That means they won't produce the claimed water vapor and may not bring up the humidity to the desired level. A few larger console models also failed to deliver the output their makers claimed, although it matters somewhat less because their overall output is much greater.

In some models, the humidistat, which controls humidity levels, was not always accurate. And most portable humidifiers won't let you set humidity levels below 30 percent. When outside temperatures drop below 20° F, even a 30 percent indoor humidity level can lead to window condensation. So you might not be able to run a humidifier when it gets that cold.


How to choose

Use Types to decide the size you want. Among tabletops, you have a further choice: an evaporative model, which uses a fan to blow air over a wet wick, or a warm-mist model, which uses a heating unit to boil water, then cool the steam.

If quiet is a must, consider a warm-mist tabletop unit. All warm-mist humidifiers were quieter than evaporative models. Some of the units we tested added little or nothing to background noise levels except mild boiling and hissing sounds. By contrast, comparably sized evaporative humidifiers generated 45 to 50 decibels on low settings, comparable to the noise from a small air conditioner, and more than 50 decibels on high settings.

All console models use evaporative technology, so if noise is an issue, either run your console several hours before bedtime and turn it off or use several warm-mist tabletop models. Obviously, the latter would at least double your cost.

Consider the importance of energy savings. In-duct systems and other evaporative models performed best on this measure. The evaporative tabletop units in our tests cost about $5 to $37 per year to run, compared with warm-mist models, which cost about $50 to $85 per year to run. The console models we tested, which were all evaporative, cost about $20 to $28 per year to run. In-duct models, while the most expensive initially, are more efficient to run than most console models, costing about $2 to $28 per year, including filter changes.

Hard water limits choices. Whether you want a tabletop or console humidifier, an evaporative or warm-mist unit, you can find one that performs very well with hard water. Those that don't perform well on this measure have lower output with hard water. For example, the output of the Hunter 34355 with hard water was 50 percent lower than its output with soft water.

A humidistat is a must. Humidistats, either dial or digital, control humidity levels and shut the humidifier off when the set level is reached. Without a humidistat, humidity levels can become high enough to form condensation on windows and other cold surfaces. Overhumidification can lead to mold and bacteria growth. Humidistats that display room humidity levels and humidity settings are best.