These and many other common problems can occur during the winter months when the heater is running more than normal.  This can especially happen in areas that have cooling systems to handle warm and hot summer months.  The duct is often designed to be optimized in the summer months and when heat season rolls around, the airflow balance is all wrong.  The solution is Zone Control.  Even in the best designed duct systems, dampers are often used to balance the airflow on site.  This is tedious and inexact... but with SmartZone controls and power dampers, your home can be comfortable everywhere year round.

"I have personally been in too many to count homes with two stories that NEED zoning... there is nothing wrong with the equipment capacity or the ductwork, they just need the ability to direct airflow in the areas that need it in different seasons of the year or even times of day"  -- SmartZone Contractor