QwikSEER White Paper

Constant Torque ECM or X-13-type Motors

Constant torque ECM or X-13-type motors have multiple torque settings instead of speed

settings. These motors are typically operated at a single torque setting, and as a result, can

provide a relatively constant airflow even as installation conditions change. Besides being more

efficient than PSC motors, the actual airflow achieved in an installation is more likely to be the

design airflow specified by the manufacturer. Unfortunately, like the PSC configuration, this

configuration cannot alter the airflow as the environmental effects change. Therefore, sometimes

excess airflow is provided, thus wasting energy and lowering the system efficiency.

Continuously Variable Speed ECM motors

Continuously variable speed ECM motors are just as efficient as other ECM or X-13 motors (and

more efficient than PSC motors), while having the additional benefit of providing constant,

manufacturer-specified airflow, independent of reasonable variations in installation and

operational conditions. However, the typical variable-speed ECM motor does not optimize the

evaporator airflow for environmental changes (changes in outdoor temperature, or return air

temperature or humidity).

A further performance improvement can be achieved if these continuously variable speed ECM

motors also adjust the airflow to changing environmental conditions. Normally, if this were to

occur, the ECM blower motor would be controlled by a digital thermostat, and the airflow could

be adjusted to better match the environmental conditions. Such a configuration would typically

be the most efficient because the motor type is the most efficient and the blower motor is only

supplying the airflow that is needed.

Variable-Speed PSC Motor

A Variable-Speed PSC Motor capability is achieved when the QwikSEER+ WattSaver control

board controls a traditional PSC motor. Although only three speeds are available instead of the

continuously variable speeds of an ECM motor and the PSC motor is less efficient than an ECM

motor, this configuration has the advantage of matching the airflow to both the environmental

and installation conditions of the conditioned space.

Not only does this system provide airflow rate adjustment similar to the best continuously

variable speed ECM motor control, the control provided by the QwikSEER+ control board

allows the motor to operate on a conventional analog thermostat.

Another opportunity is that the low-cost QwikSEER+ WattSaver board and a low-cost PSC

motor can be used together to replace any expensive ECM or X-13 blower motor and controller,

as long as a contactor can be activated by the 24 VAC to the G (green) and C (common) wires to

supply either 120 VAC or 240 VAC from that contactor to the input side of the QwikSEER+

control board. The QwikSEER+ board then determines the best of three possible operating

speeds and supplies power to the proper PSC motor speed tap.

QwikSEER+ Benefits

On air conditioning or heat pump systems with traditional analog thermostats, the HVAC

technician selects the blower speed (PSC motor), blower torque (X-13 motor), or constant

airflow setting (ECM motor) by selecting a power input port or programming the motor.