Most people know that poorly designed duct lines can lead to uneven airflow in the house. However, you may experience uneven airflow even if your system was professionally installed. Here are three reasons this may happen.
Restrictions in the Duct Lines
Air ducts are responsible for air circulation; they move air into and out of your rooms. The size of supply and return air ducts are determined by the size of the rooms, since different rooms have different air needs. For example, a small guest bedroom might not need as much air as a big master bedroom.
Therefore, anything that restricts the flow of air through the air duct leads to uneven airflow. For example, rodents can nest in the air ducts and restrict airflow, and physical damages to the duct lines can reduce their width and hence the amount of air they can channel into different rooms.
Leaks in the Duct Lines
Leaking duct lines can also lead to uneven airflow by diverting some of the air away from the ducts and by extension from the rooms. Air leaks can occur through small holes and cracks that may not even be visible to you. These cracks and holes can be caused by different things. For example, rodents can chew through the duct materials, and sealing materials (used in joints) can dry and crack.
Malfunctioning Duct Dampers and Booster Fans
As hinted above, duct runs are sized according to the air need (that depends on room size) of each room. However, your air needs aren't static; you may need to condition the air in each room differently at different times. Duct dampers help to do this by regulating the volume of air flowing through the ducts at any given time. Booster fans, on the other hand, enhance circulation in places where the airflow isn't adequate despite a perfectly functioning HVAC system.
As you can see, dampers and booster fans contribute to efficient and even airflow. Therefore, a malfunctioning booster fan or duct damper can lead to uneven airflow. For example, an automatic booster fan whose circuit has been fried will not work and may lead to uneven airflow.
Therefore, don't just assume that your HVAC system was properly installed if you are experiencing uneven airflow. Contact an HVAC technician, such as one from Butler Heating & Air, for a professional diagnosis. Who knows—you may be lucky to find that the problem is a minor issue that doesn't require a redesign of your ductwork.