A variable-speed furnace offers quiet, energy efficient comfort using advanced motor technology. Instead of only running on top speed, a furnace equipped with an electronically-commutated motor (ECM) will adjust its running speeds based on your home’s need for heat. They save energy because ECMs use much less electricity than the standard motor, and its slower running speed helps distribute the heat more evenly.
What a Variable-Speed Furnace Does
Conventional blower motors, known as permanent split capacitor motors (PSCs) use alternating current (AC) while an ECM uses direct current (DC). Since our power supply is AC, the variable-speed furnace motor has an inverter that changes the power flow to DC, which is a more efficient use of electricity.
These motors also include high tech components that work with the HVAC system to sense how much heated air your home needs, and adjust their running speeds accordingly. If it’s just a few degrees, the motor will run at a slower speed. The ECM is also capable of sensing the airflow through the blower, making adjustments for constricted airflow from dirt filters or blocked return registers.
Variable-Speed Advantages
- Cleaner air. Since a variable-speed furnace runs more slowly, it removes more airborne particulates, which creates a healthier home. Anyone who suffers from allergies to pollen, dander or mold may breathe easier.
- Less electrical consumption. Although combustion furnace efficiency isn’t measured by its electrical use alone, your monthly energy bills will drop. If the furnace is equipped with an air conditioning system, your summer cooling costs will also decline. These systems also remove more humidity in the cooling mode since the air handler runs longer.
- Quiet operation. These systems start and stop their cycles slowly. Even at top speeds, these motors are quieter than PSC motors.
- Durability. HVAC systems with variable-speed motors tend to last longer since they avoid the stress and wear that frequent starts cause.
To learn more about a variable-speed furnace, contact Roth Home & Cooling, providing trusted HVAC services for Portland-area homeowners since 1976.
