The heating, ventilation and air conditioning (HVAC) industry uses a variety of motor technologies in its equipment. Historically, the two predominant motor types have been permanent split capacitor (PSC) single speed motors and electronically commutated motors (ECM) with variable-speed capability. HVAC professionals understand the key differences between these motor types. This article aims to share those differences to you today.
For many years, PSC single-speed motor technology has been the standard in the HVAC industry. It represents the highest installed base.
PSC motors are considered single-speed (speed refers to rate of rotational motion) because they have no internal controls that can be programmed automatically to vary the rotation of the motor over an operating range. In order to make PSC motors more flexible for various applications, speed taps are included to allow the mechanical contractor to manipulate the motor’s speed to ensure that the correct amount of airflow is delivered. There is, of course, a limit to the amount of static pressure the motor can handle, so it is important to keep in mind the optimal performance and safety. As static pressure increases, a PSC motor’s performance tends to drop off because it cannot adjust torque or speed.
Because of its design, there are some disadvantages intrinsic in PSC motors. They are less efficient than other motors because they consume more watts. They are not ideal for continuous fan operation because since they run close to full speed, they use more energy than what the function requires. This also makes them less attractive for other continuous filtration applications. They are also the least quiet among the motor technologies. They do not offer customized airflow patterns that are often critical when it comes to managing humidity.
ECM variable speed motor technology is highly variable and is ideal for various advanced applications.
ECM technology is based on a direct current (DC) design that is more efficient and it runs cooler than AC PSC motors. They are, in fact, approximately 80% efficient compared to the 60% efficiency rating of PSC designs. ECM motors are programmable. In the case of a failure, the control or the motor can be replaced without having to replace the entire unit. They are also designed to run over a wide range of speeds, making them ideal for delivering airflow in a multitude of system designs. They also draw the least amount of watts, making them the most efficient motor technology. They are also the quietest among the motor technologies since they have the ability to ramp up and down slowly, making them ideal for certain applications with noise concerns.
When it comes to disadvantages, ECM variable-speed motors come at a premium cost.
To see the difference in performance between the two types of motors, check out this chart:
*Chart data courtesy of: Biemayer, P., Lutz, J., & Lekov, A. (2004). Measurement of airflow in residential furnaces*
I called Twintech during the Covid 19 crisis because our furnace was broken and it was still very cold during the nights. Dave answered all of my questions by phone but wanted to come have a look but only if our family felt comfortable having someone visit during the uncertainty surrounding the pandemic and was able to attend that very same affternoon.
He was very courteous and informative but most importantly he respected his and our safety by wearing medical gloves in our home and maintaining proper physical distancing. He reviewed the various options of the products that suited our needs going over not only price but quality of workmanship, warrantees and where the product was manufactured which were all important factors in making such a large purchase. You could tell that Dave had been in this industry for a very long time.
The installation was done by a fine young gentleman the very next day and we now have a toasty warm home to ride out this crisis in while humming along at 96% efficiency!
I would recommend this very professional, small family business for anyone in need of HVAC equipment or maintenance.
My special thanks to Twintech teams! They had replaced my furnace and A/C, and installed a new humidifier for me 2 weeks ago. Dave, the sales manager, not only provided me with an honest quote on the best HVAC products with best quality and warranties, he also arranged portable heaters for me and sent supporting docs to energy company for energy audit. Above and beyond service!
Greg, Grant, Mitch had worked tirelessly and professionally to perform the HVAC installation. They worked with professional tools, and performed proper measurement readings after installation. They are very patient with all my questions, and very pleasant to communicate.
Great work guys! This company sure knows their products and they stand behind their services. My home comfort level has improved! I am glad that I can support an ethical and honest local family business.
Professional, flexible on price and delivered on time...well done. All you can ask for when getting a new furnace.
The work was done quickly and professionally. Workers were really polite and easy to work with.
Product works great!
Furnace broke down on a Wednesday, shopped around for prices and Friday Twintechs name came up from a referral from my wife's work. Called Dave 11 am, he came over around 1 pm. Gave me a very good price, I accepted. The guys were there two hours later to take the old furnace out and install the new one. All finished by 6:30pm. Finally heat.
They were very pleasant and helpful. As a result we are doing our A/C later this year with this company.
After some extensive research, we settled on Twintech for our new furnace. The service - from Dave's initial visit - through to the installation was absolutely fantastic.
Dave was super-patient with our many questions, did not try to "up-sell" us into buying things we don't need, knowledgeable, friendly and all-around an excellent Advisor.
I've forgotten the names of the installers but they were superb as well. They showed up on-time, did all the work with no mess or intrusion, removed the old furnace and installed the new one in one day; all with no impacts to our day-to-day life.
I cannot recommend Twintech enough, especially over any of 'bigger guys' who tried to sell us a bunch of thing we don't need. Twintech were fantastic and my wife and I are very pleased with our purchase.
From the minute I met Dave and discussed my new furnace needs I knew I was in good hands. He was patient, knowledgeable and very professional through the quotation process.
Grant and Greg did an outstanding job on the install. They did a great job of explaining the defects with my old furnace. The quality of the installation was excellent and the attention to detail was on another level. The old adage You get what you pay for couldnt be more true as I feel I received great value, skilled expertise and high quality customer service. I highly recommend Twintech for all your heating and cooling needs.
Glad to have found a not-too-big local firm that provided the needed expertise, quality workmanship, and competitive pricing as well. In and out in one day, removed the old units, did a nice job installing all of the new units, and left no debris. Even have a service contract that far outshined the big company offerings. Would definitely recommend them.
Appreciated a quick response to my request. Dave and Greg were very professional and made the experience seamless.
Very professional through the entire process. Installation and removel was done on a sloppy winter day, they put down runners on the floors and stairs and when they left, there wasn;t any sign of someone being in our house. Furnace works great as promised.