What effect does a dirty air filter have on HVAC systems?

A dirty air filter significantly reduces airflow within HVAC systems, leading to several negative consequences. When the filter is clogged with dust, dirt, and other particulates, it obstructs the passage of air. This restriction forces the system to work harder to move air through the filter, resulting in increased energy consumption as the system struggles to maintain the desired temperature.

The reduction in airflow can also cause other issues, such as reduced heating or cooling efficiency, as the system may not be able to circulate enough conditioned air throughout the space. Additionally, the increased strain on the system can lead to premature wear and tear on components, potentially resulting in costly repairs.

In contrast, clean air filters allow for optimal airflow, enhancing overall system efficiency and performance while keeping energy consumption at more manageable levels. Therefore, the correct answer highlights the detrimental effects of a dirty air filter on both airflow and energy usage.