Dehumidifiers work more like vacuum cleaners. They suck in air (moist air most of the time) and expel it when it has been dried. The process usually involves the moist air passing through some coolant coils and then the moisture collected into a bucket. Dehumidifiers are made to keep the air in your home free from excessive humidity. If you notice damp spots on your walls or paintings, or notice some badass allergies creeping up on you, then there is a possibility that the levels of humidity in your space are higher than they should be.