hvacrmedic wrote:

There is however a new ECM design avialable called the
"Evergreen AH". It is specifically designed as a retrofit
for PSC motors.

http://www.thedealertoolbox.com/ever...82d3b5 e1cd0d

They are not rated at this time for furnaces, air handlers only.

What's the difference between a furnace-fan motor and an
air-handler-fan motor?

The retrofit isn't really practical from any standpoint, even
though it is possible to do.

Seems you're wrong. It's being marketed directly to HVAC repair shops
exactly as a replacement for furnace PSC motors.

"Evergreen AH is the world’s first high-efficiency ECM replacement
motor that is designed to replace factory PSC blower motors in
residential air handlers. That means you can now offer your
customers the comfort and efficiency of ECM in an easy-to-install
replacement motor.

Built from the same trusted, field-proven ECM technology that is
found in millions of OEM systems nationwide, Evergreen AH uses up
to 25% fewer watts in operating mode and up to 74% fewer Watts
than a PSC motor in constant fan."

http://www.thedealertoolbox.com/serv...82d3b5e 1cd0d

See also:

http://www.evergreenmotor.com/faq.php