The difference in pressure between two points in an air conditioning system, specifically the pressure exerted against the duct walls, indicates the resistance to airflow. This measurement, typically taken in inches of water column (in. w.c.), reflects the force needed to overcome friction and obstructions within the ductwork, coils, and filters. For example, a higher reading at the supply duct compared to the return duct signifies increased resistance, potentially caused by a dirty filter or undersized ductwork.
Maintaining appropriate levels is crucial for optimal system performance and energy efficiency. When resistance is too high, the HVAC unit works harder to deliver conditioned air, leading to increased energy consumption, reduced cooling capacity, and potential equipment failure. Conversely, insufficient resistance can result in uneven airflow and temperature imbalances throughout the conditioned space. Historically, careful manual calculations were required to estimate pressure drops, but modern diagnostic tools allow for precise measurement and analysis, enabling proactive maintenance and system optimization.
