Cold vs. Warm Air Humidifiers
Humidifiers are made to increase the amount of humidity in the air. Hot air humidifiers boil water and vent the steam into the room air. Cold air humidifiers use a membrane such as a filter surface to draw water from a reservoir. Then this increased wet surface area is exposed to a fan that evaporates the water into the room. There are a few key differences between the action of the two types. Does this Spark an idea?
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Absolute vs. Relative Humidity
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It's important to know the difference between absolute and relative humidity. Absolute humidity is the total amount of moisture in the air (temperature independent), while relative humidity is the percentage of moisture saturation in the air (temperature dependent).
Cold air humidifiers evaporate water into the air at a rate based upon the relative humidity. When relative humidity is low, cold air humidifiers work very quickly, but as relative humidity rises, the rate of evaporation slows.
Hot air humidifiers boil water and blow the steam into the air. In this way they work independently of relative humidity. They can saturate the air with water, and any excess water will simply condense and fall to the ground in the form of tiny droplets.
Microbes
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Stagnant water breeds microbes. The water in the reservoirs is stagnant unless the humidifier is on.
In cold air humidifiers microbes can grow in the water and on the filter/membrane element. As the fan blows it can blow these microbes into the air. These filters need to be changed or cleaned.
The water in hot air humidifiers is heated significantly in order to speed evaporation. This kills many microbes and prevents them from being pushed into the air.
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Minerals
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Minerals from the water build up inside humidifiers in much the same way and places that microbes do. In cold air systems the minerals can be blown into the air from off of the filter/membrane. Hot air systems are less likely to do this because most of the mineral buildup occurs on the heating element itself.
Safety
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Hot air humidifiers have a heating element in them that is capable of melting the plastic, causing leaks, or even fires. On the other hand cold air systems only have one electric part; a fan. Of the two, cold air systems are far safer.
Energy Consumption
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Considering the fact that cold air systems only have one energy-consuming part, while hot air systems have two, they are definitely the more economical of the two. The heating coil alone in the hot air systems consumes far more energy than the fans in either system.
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References
Resources
- Photo Credit humidifying lotion image by Indigo Fish from Fotolia.com
