Furnaces generate heat, and blower motors power the fans that distribute heat throughout the structure. They must be powerful enough to send heat throughout a home and durable enough to constantly cycle on and off.
Furnaces distribute heat through homes using one or more fans. While they are somewhat less efficient than boilers, their simplicity still makes them a popular heating option. Much of their inefficiency is due to the fact that heated air cools off faster than heated water, but some is also due to their fans, which require powerful motors to spin.
Blower motors are generally powered by a separate electrical connection, so homeowners installing a new furnace need to ensure that they have access to an electrical outlet. For especially large systems, a dedicated line may be necessary. In addition, a single-furnace system often has several blower motors, each requiring a sufficient supply of electricity.
Moving parts typically break more often than non-moving parts, and blower motors and the components they connect to are no exception. Small defects in fans can cause uneven rotation, which can strain a motor over time, so checking fans on occasion may prevent expensive repair bills. Blower motors are typically connected to a resistor to change the speed of connected fans, and this resistor can degrade and break over time.