I'm pondering as to whether it's possible to convert a single speed pump to a 2-speed without replacing the whole motor /w a 2-speed model.
Are the motor manufacturers using a simple 2-mode VFD or variable frequency driver design in their 2-speed motors, say 30/60Hz off of a rectifier+pwm?
Here's a VFD, same style of circuitry design concept as they use in the VS pumps such as the IntelliFlo or the VS Pump controller: AccuDriveXS. But this one, unlike a 2-speed pump, is actually variable, not just dual mode.
http://www.ebay.com/itm/140969496835?ss ... 1438.l2649
Of course its amperage is too low, but this is just a lower cost one I grabbed the link on.
Or do you suppose the motor manufacturers such as AO-Smith/Century are using the age-old "2 separate windings with a different number of poles" and simply switching between them through the terminal board?
I almost think they're doing the latter. If so, well, a VFD would be in order.
I get the idea it's the latter from here: http://www.pumped101.com/vf101.pdf
Some fun stuff on the subject.
As for VFD's, are there any that are as power efficient as the native 2-speed pump design? Or are they all power hogs?
I look forward to your thoughts, DIY success stories, or hair brained ideas on the matter.
EDIT: Changed from "stationary switch" to "terminal board". Still understanding pump terminology.