Whisperflo 2 speed full rated- 1hp vs 3/4 hp


Well-known member
May 25, 2007
Awhile back I emailed Pentair asking why they didn't use the energy efficient version motor for their two speed pump. I just got the response, saying they consider the 2 speed energy efficient because of the lower speed (duh) but if I wanted a motor with less amperage to look at the WFDS-4 1 hp 2 speed. So I did.

This is a comparison between the two 2 speed, full rated options-

Spec 1 hp 3/4 hp

SF 1.65 1.63

Full speed amps 7.8 14.6

Low speed amps 3 4.7

Looking at the flow chart, the 1 hp has about 15-20 more GPM than the 3/4 hp at any given head. I know the higher flow will increase head, but unless I'm missing something (likely), even if the head loss and flow was identical it appears the 1 hp would use less energy, and since it isn't likely that head loss would be identical it would use less energy AND provide higher flow, allowing for shorter run times and even more savings.


Seems like a no brainer, but perhaps that's what I'm being?



TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
The electric company charges by the watt, which is volts * amps. The WFDS-3 is 115 volts only, while the WFDS-4 is 230 volts only. To compare the electric usage you need to multipy the 230v amps times two (or divide the 115v amps by two) before comparing them to the 115v amps. So it is really:

Full speed amps 15.6 14.6
Low speed amps 6 4.7

230v allows you to use thinner wires for the same power, so the lower amps does get you something (thinner wire), but not what you were actually looking for (less cost).


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
I think you may be comparing apples to oranges. Double check the voltage drive and you might find that they are different. Power = Volts * Amps.

My guess is the 3/4 HP is rated at 115v while the 1 HP is at 230v. This is pretty typical.


Well-known member
May 25, 2007
Well son of a...

The 1 hp is only 230v.

Funny how pentair knew I was looking for lower electrical costs and recommended this one...

Thanks fellas :)