As HVAC products become increasingly energy efficient across the board, ECMs are gaining in popularity, especially in furnaces, packaged products, condensing units, and air handlers. The variable-speed motors are based on a direct-current (dc) design, as opposed to the alternating-current (ac) design of the single-speed permanent split capacitor (PSC) motor. Due to its ability to operate at different speeds, the ECM is inherently more energy efficient and runs cooler than single-speed motors.
The energy savings and flexibility of the ECM have made its use so preferable that in Ontario, Canada, a recent change to the Ontario Building Code will require that furnaces installed in new-construction projects in the province must be equipped with an ECM, after Dec. 31, 2014.