During an inspection, what indicates that a furnace might not be operating efficiently?

Inconsistent heating in various rooms is a strong indicator that a furnace may not be operating efficiently. When a furnace is functioning properly, it should provide a consistent temperature throughout the home. If some rooms are significantly warmer or colder than others, this could suggest several potential issues. For instance, it might indicate that there are problems with the ductwork, such as blockages or leaks, which can impede the flow of heated air. It can also signal that the furnace itself might not be distributing heat evenly, possibly due to age or a malfunction. This inconsistency in heating often points to inefficiencies in the system that could lead to higher energy costs and decreased comfort.

Modern thermostatic controls, clear air ducts, and recent maintenance records generally suggest better performance and efficiency, so they do not indicate inefficiencies in the same manner as uneven heating does.