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Thirty-two years after ECM (electronically commutated motor) technology was introduced to the residential and light commercial HVAC industry, the indoor blower motor segment of this industry is now almost completely converted from PSC to ECM. Interestingly enough, the first application for ECM in the HVAC industry was also the indoor blower motor. The constant air-flow “variable speed” indoor blower motor was introduced by GE* in 1987.
"Part 2: EC Indoor Blower Motors, Resistance is Futile", by Christopher Mohalley. August 2020 feature reposted with permission from RSES Journal, www.rsesjournal.com.
A common misconception about EC indoor blower motors is that they all maintain airflow and solve airflow issues such as undersized ductwork and/or dirt load on the air side components. In part one of this article (see June 2020 issue of RSES Journal), I explained that there are actually two different types of EC indoor blower motors, constant airflow and constant torque.
"Part 3: EC Indoor Blower Motors, Resistance Is Futile", by Christopher Mohalley. October 2020 feature reposted with permission from RSES Journal, www.rsesjournal.com.
In Parts 1 and 2 of this series (published in the June and August 2020 issues, respectively, of RSES Journal), I discussed how to adjust airflow and the airflow performance characteristics of EC indoor blower motors. The information in those articles can also be used for diagnosing operating ECMs that exhibit airflow related issues.