Which type of motor is least likely to find a use in HVAC applications?

In HVAC applications, the type of motor that is least likely to be used is the universal motor. Universal motors are designed to operate on either alternating current (AC) or direct current (DC) power and are typically compact, lightweight, and high-speed. However, they are not well-suited for continuous running applications and tend to wear out quickly under sustained operation, which is a common requirement in HVAC systems.

In contrast, capacitor-start motors are generally reliable for starting torque in applications such as compressors and fan motors, while capacitor-start, capacitor-run motors are efficient for continuous operation, combining good starting and running characteristics. Shaded-pole motors are often utilized in small fans or blowers, particularly when low cost and simplicity are more important than efficiency or high torque.

Due to their durability and performance characteristics, the other types of motors are preferred in HVAC applications, further solidifying the universal motor's position as the least appropriate choice for this specific industry.