Ever since Nikola Tesla invented the modern induction motor, we have been struggling with varying the speed of motors efficiently and reliably. The trouble in the HVAC industry is that there are several different types of technologies in play, and they can easily get confused. ECM (electronically commutated motor) In residential and light commercial HVAC, […]

This article is an updated version of another HVAC School article on oversized equipment. This edition is a joint effort by Genry Garcia of Comfort Dynamics, Inc. and Kaleb Saleeby. Both of them are regular contributors to HVAC School, and we are grateful for their contributions. Thanks, guys! The symptoms and consequences of oversized heating […]

Fundamentally, three-phase, alternating current motors are about as simple as a motor gets. The power company produces three phases by spinning magnets. Then, on the other end, we produce electromagnets that spin the motor according to the same 60 cycles per second frequency (60hz). All three phases are 120 degrees out of phase from one […]