When assessing furnace operation, what does a high temperature rise typically indicate?

A high temperature rise in a furnace typically indicates insufficient air flow. When the air flow is inadequate, it prevents the furnace from properly distributing heat throughout the system. This results in an increase in the temperature of the air that is being circulated, as the furnace continues to generate heat without adequate air movement to carry it away.

In a properly functioning system, the air should be able to flow freely, absorbing heat and delivering it evenly throughout the space. If there is a blockage or a restriction in the air ducts, or if the air filters are dirty, the system struggles to move the air effectively, leading to elevated temperature readings at the output. Therefore, assessing high temperature rises in this context is crucial for identifying potential issues with airflow and ensuring the furnace operates efficiently and safely.