What will happen to static pressure (resistance) if a forward curve fan has a dirty filter?

When a forward curve fan has a dirty filter, the static pressure within the system will increase. This occurs because the dirt and debris in the filter obstruct the airflow, creating additional resistance that the fan must work against. As a result, the fan experiences a higher pressure drop due to the accumulation of particulate matter, leading to increased static pressure in the ductwork.

In ventilation systems, filters are designed to capture particles from the air, improving indoor air quality but also adding resistance to airflow. As a filter becomes dirty, it inhibits smooth air passage, causing the fan to work harder to maintain the desired airflow. This increase in resistance is reflected in the rise in static pressure readings.

Understanding how filters impact system performance is critical for maintaining efficiency and ensuring the proper operation of HVAC systems. Regular maintenance, including filter changes, helps prevent excessive pressure drops, ensuring optimal airflow and energy consumption.