Difference between an Air Conditioner and a Dehumidifier

by : rsbombard

Someone selling an air conditioner would try to convince you at any cost that you must buy an air conditioner and for that if he has to tell a few half-truths or even lies, he would do that. Thing is you should know beforehand so that you can't be sold a bluff. One such point is the dehumidifying capacity of air conditioners. While air conditioners do dehumidify, their primary purpose is to make the environment comfortable.

For the job of dehumidification we have refrigerant dehumidifiers. The compressor of a refrigerant dehumidifier is rated at anything between 13000 and 15000 BTU. In place of that, a residential central air system has a compressor rated at 30000 BTU or higher. The air conditioners used for commercial purposes have even higher ratings. Now with such high ratings and over 50% of the energy being expended by air conditioners in dehumidification, they are apparently good agents of dehumidification.

But there is more to it. In case of a refrigerant dehumidifier, subject to the surrounding conditions, the temperature of the evaporator coil is about 20 to 30 degree Fahrenheit below the dew point temperature of the surrounding air which is at about 28 degree Fahrenheit. However, when we are talking about an air conditioner the equation changes. An air conditioner's evaporator coil would only be 10 to 14 degree Fahrenheit colder than the surrounding air. The theory is that, the more a coil is cold, thee greater the moisture vapor that will be removed from the air. What this means is when a dehumidifier is able to dehumidify a space in 24 to 36 hours, an air conditioner will take much longer.

There are also the evaporative coolers which are extensively used in the dry climates of the desert and mountain regions of the western United States. The evaporative coolers, as the name suggests uses evaporation to cool the air. The result is that the humidity increases in the air. So, if anyone plans to buy an evaporative cooler, thinking it will also solve is dehumidifying problem, he should think again. In fact a dehumidifier and an evaporative cooler shouldn't be used together as the cooler will nullify the effects of the dehumidifier.

So, it must be understood that air conditioners are made to maintain a comfortable temperature indoors when the outdoors are unpleasant. In the process it might dehumidify the rooms. But that certainly is not what it is meant to do.