What common symptom indicates a dirty filter in a gas furnace?

A dirty filter in a gas furnace commonly leads to reduced airflow and a drop in system efficiency. When the filter is clogged with dirt, dust, and debris, it restricts the flow of air through the furnace. This restriction can cause various issues, such as the furnace struggling to pull in enough air for proper combustion and heating, leading to a decrease in the overall efficiency of the heating system.

Inadequate airflow not only makes the furnace work harder to maintain the desired temperature but also can lead to additional problems such as overheating, since the heat exchanger may not receive sufficient airflow to cool it down effectively. This can impact the longevity of the system and may even lead to failures if not addressed. Thus, recognizing reduced airflow as a symptom of a dirty filter is crucial for maintaining optimal furnace performance and ensuring efficient operation.