Variable speed furnaces use advanced motor technology to run more efficiently. Since the fan is not set to run on top speed constantly, it runs quieter than older furnaces. These systems are equipped with electronically-commutated motors (ECMs) that automatically adjust running speed based upon your home’s need for heat. ECMs save energy because they use significantly less electricity than your standard motor. Since the motor runs at a slower speed, the air within your home is distributed more evenly.

ECMs use direct current (DC) unlike conventional blower motors which use alternating current (AC). The power supply is still AC but the variable-speed furnace motor uses an inverter that changes the power flow to DC…which is a considerably more efficient use of electricity.

Another advantage is that the ECMs are equipped with high tech components that work with the HVAC system to detect how much air your home requires to meet the set temperature on your thermostat and adjusts running speed accordingly. If the set temperature is only a few degrees different that the actual indoor temperature, the motor will run at a slower speed. Adjustments are automatically made for constricted airflow based upon sensors that detect airflow through the blower.

With a variable-speed furnace, you will enjoy cleaner air. Since the fan runs more slowly, it helps to remove more airborne particles from your home. People who suffer from allergies are likely to breathe easier. When the system is in cooling mode, it removes more humidity since the air handler is running for a longer period of time.

Variable-speed motors tend to last longer than traditional motors since they aren’t running at top speed constantly. This helps to reduce the amount of wear and tear on the entire system, which will assist in extend the life of your furnace.