Replacement of disposable air filters in HVAC systems is generally based on which parameter?

The most effective parameter for determining the need to replace disposable air filters in HVAC systems is the pressure drop percentage. This measurement indicates how much airflow is being obstructed by the filter. As dirt and contaminants accumulate on the filter, the pressure drop increases, which means that the system is working harder to circulate air through the filter. A significant pressure drop can lead to decreased efficiency and performance of the HVAC system, which may cause further strain on the equipment and potentially lead to higher energy consumption and repair costs.

While the color change of the filter can give a visual cue regarding dirt accumulation, it is not a reliable or precise measure, as different filter materials may change colors at different rates regardless of their actual condition. The time elapsed since the last replacement is also not a definitive measure, as usage patterns and environmental conditions can affect how quickly a filter becomes clogged. Lastly, the cost of replacement, while a practical consideration for maintenance schedules, should not dictate the timing of a filter change since system performance and efficiency are prioritized for optimal operation. Therefore, monitoring the pressure drop percentage provides the most accurate and functional approach for filter replacement in HVAC systems.