What is a common cause of elevated static pressure in the duct system?

Elevated static pressure in a duct system is commonly caused by under-sized ductwork. When ducts are too small for the volume of air being delivered by the HVAC system, the air has to be forced through a narrower space, which increases resistance and leads to higher static pressure. This can result in decreased system efficiency, increased energy costs, and potential issues like inadequate airflow to certain areas of a building.

While high-efficiency filters, properly sized returns, and flexible duct connections can affect airflow, they do not typically lead to elevated static pressure in the same way that under-sized ductwork does. High-efficiency filters, for example, may restrict airflow if they are too dense for the system; however, their primary impact is generally associated with the need for higher fan power to compensate for that restriction. Properly sized returns help maintain balanced airflow and reduce static pressure instead of contributing to it. Flexible duct connections are more about the way ducts are installed and can help with airflow dynamics rather than causing significant static pressure issues on their own.