Place the dehumidifier in the proper location near the furnace. It must sit as close as possible to the furnace's return air duct, with plenty of room for access to the filter access panel on the front of the dehumidifier and the electrical access panel. The ambient temperature around the dehumidifier should remain within 40 and 125 degrees Fahrenheit, with an accessible grounded electrical source nearby.
Disconnect the dehumidifier from the power source if applicable.
Attach 3/4-inch PVC pipe to the condensate drain outlet on the furnace. The instruction manual for the dehumidifier should outline the location of the condensate drain outlet if it is unclear.
Run the PVC pipe so that it reaches an outdoor drain.
Connect the discharge air supply on the dehumidifier to the return air supply on the furnace using the 10-inch duct.
Attach the return air supply on the dehumidifier to the return air supply on the furnace using the other length of 10-inch duct. This should be located near the furnace's return air grill. There are two connections from the dehumidifier to the return air supply on the furnace. The first one (Step 5) acts as an intake for the dehumidifier. The second, expels the air back into the furnace's return air supply after it has been dehumidified. This air is what gets pushed through your vents.
Close up the connections with sealant to ensure they remain efficient and don't lose air through the connections.