Imagine an HVAC system that provides consistent temperatures throughout your building, excellent humidity control and quiet operation. Those are the kind of benefits that electronically commutated motor (ECM) technology can bring. ECMs are also highly efficient, reducing your energy costs.

Ebb and flow

Outdoor weather conditions vary day to day, but the need for proper airflow indoors never changes. Extreme temperature variations within a building is a common complaint, and sudden bursts of warm or cold air can be disruptive and make people feel less comfortable. Consistent airflow is desirable because it minimizes this type of temperature stratification, particularly in multi-story buildings.

Often, heating and cooling units driven by oversized, fixed-speed blower fans don’t cycle on and off correctly, reducing comfort. A variable-speed ECM unit provides a cost-effective solution to these problems.

A tale of two motors

Permanent-split capacitor (PSC) alternating-current (AC) single-speed motors have been the standard in the HVAC industry for many years. Their popularity is due to their simplicity, reliability and low cost. However, PSC motors have a number of disadvantages.

Their operational efficiency is low — typically no higher than 60%. PSC units aren’t programmable, and their speed can’t easily be adjusted. Finally, PSC motors don’t offer customized airflow patterns, making it more difficult to control humidity and maintain consistent air stratification and temperatures.

Unlike conventional, single-speed blower motors, permanent magnet brushless direct-current (DC) ECM models operate at a wide range of speeds. This allows blowers to adjust and only deliver the airflow that’s needed by the system. The technology works without external sensors; the motor is programmed to adjust its speed as the torque changes according to pre-set conditions that correlate with the range of static pressures in the ductwork. The improved speed control allows the heating and cooling system to maintain the proper airflow and a constant temperature, improving occupant comfort.

Benefits of ECMs

Variable-speed ECMs provide more than just constant temperature control. Additional benefits include:

• Energy savings. The soft-start capability of ECMs, and their ability to run at low speeds for long periods, reduces energy use by up to 50%.
• Improved indoor air quality. A variable airflow increases humidity control and occupant comfort.
• Quieter operation. Longer operating cycles reduce the abrupt noise created when conventional blowers turn on and off frequently.
• Low maintenance. The use of true ball bearings decreases the need for oiling, and the varied startup speeds reduce stress on the mounting hardware.
• Embedded motor control. Motor control is embedded inside the motor housing. There is no need to mount a separate motor drive enclosure.

ECMs typically cost more than standard single-speed units, but the benefits in reduced energy costs, improved comfort and less maintenance more than make up for the extra cost and provide a good return on your investment. Your local electric cooperative also offers Power Moves® rebates for qualifying energy efficiency upgrades to your business or facility. Contact your local electric cooperative’s energy advisor for details.