When furnaces produce heat, they need a motorized fan to circulate the air throughout the structure. An ECM furnace is equipped with an ECM (electronically commutated motor) to circulate hot air into the ducts that run through the walls of the building.
How ECM Motors Work
ECM motors, also called DC (dual control) or variable-speed motors, provide constant airflow throughout the building. Unlike a conventional furnace fan, it automatically adjusts the speed of the airflow so it is even everywhere, regardless of the configuration of the air ducts.
ECM furnace motors use significantly less electricity than traditional furnace fans. Depending on usage, an ECM furnace fan costs between $40 and $300 annually to operate in 2011, which is around 10 times less than it costs to operate a furnace with a traditional furnace fan.
Because it automatically adjusts itself, ECM furnace fans keep the temperature more stable in different rooms of the building. It is less noisy than standard fans and does not dry out the air inside like older-style fans.