What is a common indicator that a gas furnace requires servicing?

Increased utility bills can be a significant indicator that a gas furnace requires servicing. When a furnace is not operating efficiently, it tends to consume more fuel or energy, leading to elevated utility expenses. This inefficiency can result from various issues, such as a dirty burner, malfunctioning components, or airflow problems. Therefore, when homeowners notice a sudden rise in their heating bills without an increase in usage, it often suggests that the furnace is not performing optimally and may need professional attention.

Other choices represent conditions associated with a well-functioning furnace or routine maintenance practices. Consistent heating throughout the house typically indicates that the furnace is working properly, while a stable burner flame shows that the burner is receiving gas and igniting correctly. Regularly replaced filters are a good maintenance practice but do not necessarily indicate that a furnace needs servicing; instead, they help keep the system running effectively. Thus, increased utility bills serve as a more direct signal of potential issues within the furnace requiring servicing.