I know a HO who runs the fan on his Ruud UBHC-17J11NFD air handler (2.5 ton heat pump) continuously in the summer to help keep the temperature a bit more consistent between the upstairs and downstairs, so he figures swapping the OEM PSC fan motor for an ECM motor, such as the Evergreen, might pay for itself. The Evergreen mfr/distributor says the following:
"No stock catalog replacement motor is an exact replacement for an OEM Factory Authorized part, standard stock PSC motor or ECM motor. It's the contractors job to ensure proper airflow to meet cooling or heating needs as required for the OEM equipment, and ensure that can be achieved when replacing an OEM motor with a generic replacement motor.
The OEM body of motor in this system is 4.48" long with a 3.25" shaft.
The Evergreen AH, which would be my best recommendation for an ECM replacement, pending fit, is 5.75" long with a 5" shaft.
Both motors are standard 48Frame (5.6") diameter motors.
Many Rheem systems also have special Rheem mounting brackets that would not work with an Evergreen, the contractor would need to get a standard torsion flex or wire form mount to install the motor.
Your contractor is the best person to determine mechanical fit.
The Evergreen AH Model #6001 is the 1/2Hp CCW rotation (same rotation as the OEM motor). The lower 2 or 3 speed selections would be tried (5 available on the AH ) by the contractor to match the airflow of this OEM 2 speed 1/4Hp motor."
The HO's contractor says, "I don't know what the savings would be versus the expense to install this motor. I don't think there are any savings, unless this is used as a variable speed motor which would require variable speed controls."
So my questions are 1) Is it even physically possible to swap these motors, and 2) How soon, if ever, would the new ECM pay for itself?