A study conducted by the Canada Mortgage and Housing Corporation in 2009 found that when dehumidifiers were running, the moisture levels in basement air were less than moisture levels in outdoor air. The study also concluded that the effectiveness of dehumidifiers was only observed in basements.
Main floor humidity levels often fluctuated in accordance with outdoor humidity levels, despite the us of a dehumidifier in the home. Dehumidifiers with larger coils were found to be more effective at removing moisture from the air than dehumidifiers with smaller coils. Proper insulation in a home is also very effective at controlling moisture levels in both the basement and main levels.