What is a common cause of insufficient airflow in heating systems?

Insufficient airflow in heating systems can often be traced back to dirty filters. When air filters are clogged with dust, dirt, and other debris, they impede the free flow of air through the system. This restriction can lead to a variety of issues, including decreased efficiency of the heating system, increased wear and tear on components, and uneven heating throughout the space.

Regular maintenance, including changing or cleaning filters, is essential to ensure that the airflow remains adequate. This not only improves comfort levels but also helps maintain the longevity of the heating system. Addressing dirty filters is a relatively simple and effective measure that can prevent more serious problems from developing down the line.

The other options may influence the heating system's performance in various ways, but they do not directly cause insufficient airflow in the same manner that dirty filters do. For example, high thermostat settings do not restrict airflow; they simply demand more heat. Improper refrigerant levels pertain more to cooling systems than heating systems, and flexible duct installation issues can lead to airflow inefficiencies but are typically identified through other symptoms.