So when should you use a dehumidifier? You will mainly use a dehumidifier in late spring, summer and early fall. Some climates and homes tend to have higher humidity levels, so you'll need a dehumidifier in those cases. Dehumidifiers can help eliminate existing mold problems, but they should also be considered as a way to prevent future mold in your home. No, there is no need to keep the dehumidifier running constantly.
Usually, it is enough to operate the unit when the humidity level is 50% or higher. A good rule of thumb to remember is to maintain a comfortable humidity level of 30 to 50% in most homes.