Thank you for your question regarding the AR80X exhaust fan. The backdraft damper on this unit stays slightly open to keep the temperature of your duct more line with the temperature of your bathroom. This prevents condensation and moisture from forming inside your duct work. In the event of airflow into your duct, this door would close, preventing air from blowing into your bathroom. If you have any further questions about the operation of this fan, please call Technical Support at 1-800-637-1453.
Date published: 2016-12-16