Most problems stemming from poor duct layout are the result of inefficient return ductwork.
Many homes have a supply duct for each room, but only a single return duct located in a central portion of the home. Air pressure imbalance Poor duct layout causes pressure differences within a home. When interior doors are closed, it becomes difficult for the air in these rooms to circulate back to the return duct. The pressure increases in the closed off rooms, and decreases in rooms open to the air return. This uneven pressure can cause air leakage throughout the home.