What’s the difference between a PSC and ECM motors, and Why Should I care?

PSC Motors

psc and ecm motors 1A PSC or permanent split capacitor is a type of motor that is designed to do two things. It turns on and it turns off. The electrical output of the motor is not controllable and there are no speed variances to control. Because the motor operates at a constant speed, the use of energy is a constant and efficiency is lost.


ECM Motors

psc and ecm motors 2ECM or electronically commutated motors save energy and improve the efficient movement of air through your unit. ECM motors allow for variable speeds which can correspond to the unit’s call for air flow. Typically, an ECM motor will slowly come on and increase the speed of the fan gradually as opposed to just coming completely on at startup. This saves energy and further, the ECM will only reach a maximum speed that matches the setting called for by the thermostat.

And Why Should I Care?

bag147782_150An ECM will save you money in heating and cooling costs as it has proven to decrease energy usage by as much as 75%. An ECM uses ball bearings that do not require lubrication and maintenance. The motor is not prone to overheating and less maintenance will be required over periods of time because the motor uses a soft stop and start. The usage life of an ECM is approximately 90.000 hours and surpasses the PSC motor by 40,000 hours. An ECM increases comfort levels because rooms stay consistently cool/warm. Temperature drops and spikes are uncommon and the overall impact is a sense of deeper comfort in your dwelling space. Ultimately, you will experience a better air quality by using an ECM because the air flow stops less preventing air pollutants and particulates from settling into sections of ducts and other parts. More air flow means your filters will actually do their job and keep the air cleaner that you and your family will breathe.


Don JohnsonDon Johnson is the President of Freedom Heating and Cooling in Birmingham, Alabama which offers home owners tools including:
9 Things to Check Before Calling for Service on Your Air Conditioner or Furnace”,  a resource to help home owners save on HVAC problems
The Home Owner’s Guide to Hiring a Heating and Air Conditioning Company“, a quick read on how to guarantee you never suffer by hiring the wrong contractor.
The Ultimate Home Owner’s Guide to Designing an HVAC System , a 59-page eBook covering the 9 steps to building a Complete Home Comfort System.   Contact him at 205-444-4444 or connect on facebook or Google +