Easy Air Flow
You should place the dehumidifier in the most humid part of the home, or where there has been a significant leak or moisture problem. However, the dehumidifier should not be placed on water, a damp floor or moist carpet. It should be at least 6 inches from a wall where air can flow to and through the unit on at least three of the sides. You should avoid setting up the dehumidifier in a corner or near a large piece of furniture. If the unit is placed in a basement, keep it away from boxes and storage units, or near a water heater or furnace. Do not set up the dehumidifier near an open door or window.
Some dehumidifiers drain the excess moisture pulled from the air into a removable pan or water container within the unit itself, but other styles have a hose that runs out of the dehumidifier where the water drains. If this is the case, the dehumidifier should be in close proximity to the drain but still far enough away so the water runs completely away from the unit and directly into the drainage area without leaving pools of water under or near the unit.
Maneuver the electrical power cord of the dehumidifier away from the unit and the drainage hose or drain itself to protect from electrical shock. Use an electrical extension cord if needed. Also, the unit should be the only appliance plugged into the single wall outlet. Since the unit could be running for many hours at a time, this helps reduce the chances of overloading a circuit.
Most dehumidifiers have the controls on the side or top of the unit. You want to position the unit so that you are able to reach those controls on a regular basis without having to move the unit. When the dehumidifier is first turned on, be sure to adjust the controls so that the it works at its highest level. This will help the initial dehumidifying process and bring about the desired humidity level more quickly.
Care and Cleaning
You'll also want to keep in mind maintenance when deciding where to place the dehumidifier. To keep the filters and coils clean from dirt or dust, you need to be able to maneuver close enough to the unit to use a dust cloth or vacuum attachment. Since it's important to scrub out the water container with soap and water on a regular basis to prevent mold or mildew, you'll want the unit's placement to allow for easy access to that container.