Warm-Mist Humidifiers

Warm-mist humidifiers are soothing but may not be best for small children

Warm-mist humidifiers can make a room feel warmer, allowing you to bump your thermostat down a notch or two without feeling cold. Because warm-mist humidifiers boil water before expelling it into the air, they kill bacteria, and they don't require the ongoing expense of filters that must be changed. These models are also quieter than evaporative humidifiers with fans. However, these advantages are offset by higher energy use, which makes them more expensive to run. Another problem is that minerals dissolved in the water can build up on the humidifier's heating plate, reducing its performance. Some warm-mist humidifiers come with mineral absorption pads to reduce this problem; others must be scrubbed daily. Experts (and parents contributing to opinion sites) advise caution with warm-mist humidifiers, especially in a child's room where curious hands could tip over a humidifier filled with hot water. These models are not recommended for people with asthma, because hot or warm mist can irritate breathing passages.

Many of the cool-mist humidifiers covered in this report, including the two Air-O-Swiss models and the Sunpentown SU-4010 (*Est. $80) , can produce both warm and cool mist. Models that produce warm mist only are generally cheaper, but they do not fare nearly as well in reviews. We found the strongest recommendations for the Vicks Warm Mist V745A (*Est. $40) . This model gets 4 stars on average from users at Drugstore.com and Walmart.com and 3.5 stars on average from 300-plus users at Amazon.com. Users generally like that it is inexpensive and lightweight, and many also say that it will run all night on a full tank. Most users say that this adjustable humidifier runs quietly on its lower setting, although some complain that it is too noisy on high. Users generally agree that this humidifier needs to be cleaned frequently to prevent mineral buildup; several recommend vinegar for this purpose

We also saw more durability complaints for the Vicks Warm Mist V745A than we did for most cool-mist models. Some owners report breakdowns within weeks or even days after purchase. Leakage is another common problem; although some users insist that the machine will not leak if it is maintained properly, others claim that theirs developed leaks despite regular and thorough cleaning. Also, in professional tests, this humidifier comes in at the bottom of the pack. Its moisture output and ease of use are acceptable but not great, and it gets very low scores for energy efficiency.

The only other warm-mist humidifier to earn any positive recommendations in our sources is the Holmes HM5305-UC (*Est. $35) . In humidifier tests by the Good Housekeeping Research Institute, this model is the quickest at raising the humidity in the testing room, but it also uses the most electricity of all the models tested. Editors also quibble with the fact that its humidistat has manual dial controls rather than digital ones -- although this is an improvement over the Vicks V745A, which has no humidistat at all. User reviews for this model, however, do not back up professionals' recommendations. At Amazon.com, the Holmes HM5305-UC earns an overall rating of only 2.5 stars from about 75 users. Users say it offers good moisture output and quiet operation, and they like that it has no filters to replace. However, we read many complaints about its durability. In addition to the usual problems with leakage, many owners report that the heating element actually warped or melted the water tank. "I'm lucky it didn't cause a fire," reports one user. A less serious but still annoying problem is that the tank can be difficult to fill.