Smart Motors –- Saving Energy by Running Motors Smart Instead of Hard

The motors driving your heating and AC units generally only have one speed – they’re either full speed or stopped. To regulate temperatures or airflow, the motors alternate between on and off to achieve the desired climate. This on/off action is similar to driving your car by alternating between flooring the gas pedal and slamming on the brakes. In addition to being an enormous waste of energy, it’s also very hard on the car, or in this case the HVAC unit.

Stop and Go Signs

In an effort to make motors more efficient and reduce wear and tear, the Variable Speed Drive (VSD) or Variable Frequency Drive (VFD) was introduced to allow motors to run at varying speeds. With these drives, your motors can start up more slowly and build up to max speeds only when needed – like on those 99 degree swampy days of summer –  and run at lower more efficient speeds the rest of the time.

The VSD and VFD drives function like a brain for the motor. They tell the motors exactly how fast and how long to run to maintain desired temperatures, airflow, etc. Motors running at full speed use nearly 8 times more energy than a motor running at half speed. At lower speeds, your motor is still able to provide you with ideal comfort but at much less cost. And your units don’t get whiplash from slamming on the breaks constantly.

The drives can also come with other nifty bells and whistles. Some can alert you about HVAC equipment malfunctions or tell you when the unit needs maintenance.  Alerts can save equipment downtime headaches because repairs can often be done before anyone even notices a problem. On-demand maintenance means your units tell you when they need cleaning and filters changes, so they are always functioning at their peak efficiency.

VFD and VSD drives can be used on almost any type of motor-driven equipment, including fans, pumps, compressors, etc. They can be paired with high efficiency motors for a double whammy of efficiency. Both VFD/VSDs and high efficiency motors qualify for rebates from local energy providers such as NSTAR and National Grid.

To find out if VFD/VSDs are right for you, please call us or visit our website at

Variable Frequency Drive (VFD)
Variable Frequency Drive (VFD)