FAQ on dehumidifiers

Question: Dehumidifiers do well in basements, since we're mainly interested in dryness, and usually not coolness. Wouldn't we be better off, though, putting a window air conditioner in a basement window, and getting the additional benefit of cooling? Would the window unit do as good a job of dehumidifying?


The window air conditioner will cool the basement and shut off when it is cool enough to satisfy the thermostat. The RH may well be in the 90% range at that time. So you will have a nice cool and damp basement. The dehumidifier has a sensor inside which responds to humidity. It will run until the air becomes dry to the setpoint of the dehumidifier - if you want the benefits of both then you will probably need both. Remember, cold air can not contain the same amount of water that the same volume of hot air can so if you cool the basement down to 50 degrees the relative humidity could be 100% but the total quantity of moisture in the air will be less than it was when the air was 80 degrees. So you might consider running an air conditioner and a small heater to warm the air back to 70 degrees or so to decrease the relative humidity. But . . . . . . . that is exactly what a dehumidifier does!! The heat from the motor and the heat of condensation are kept in the room to rewarm the air which was cooled by passing over the evaporator coils in the unit.

Bob -- http://www.MisterFixit.com

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