Replacing pump motor

[mas985]

Yes, the efficiency on low speed is quite low. Besides the power factor, the main reason for low efficiency is the secondary winding is much thinner (higher gauge) wire than than the primary winding so it has very high resistance. That is the only way they can make a dual winding motor with the same diameter as the single speeds. Improving the power factor helps but improving 45% efficiency by 20% is still only 54% efficiency and that is not better than a VS at any speed.

A VS can maintain high efficiency down to the lowest speeds because it changes the line frequency and voltage plus it always uses the same winding. One thing to note is the Intelliflo shows a higher efficiency at all speeds while the EcoStar shows a significant decrease in motor efficiency (33%) but that can't really be true because the EcoStar has a much better energy factor at 1000 RPM speed than the Intelliflo. Plus the wire to water efficiency of the EcoStar is 35% (Curve-C) at 1000 RPM which cannot be higher than the motor efficiency so there is clearly an issue with some of the data. Other issues with the data include the Whisperflo where the Whisperflo full rate and up rated version of the same THP pump should be identical and in some cases they are way off. However, from my own observations, most of the data seems to be pretty reasonable but there some glaring errors.

[bbsmith]

Thanks for all the input.

But after reading thru everything I am a little confused?

Which type of motor is more energy efficient (uses less KW or Amps to run a pool, Cost less)
VFD or ectro-mechanical hi-E 2-speed?

And does the ImPower have the same efficent as a VFD? The specs say that the ImPower has max 1.25 Output (1 HP up-rate) and 3 speeds (3450, 2600, 1725)

[PoolDoc]

ImPower appears to be a VFD with preset, rather than variable, speeds. It also has a pretty inflexible -- and unchangeable -- control program.

Mark (mas985) has looked at motor efficiency more than I. But from what I can tell:
+ companies (including AOSmith) haven't published motor efficiency figures for fractional (under 5HP) motors.
+ the California data, which shows OVERALL efficiency of pumps, in some cases compares identical wet ends mated with either dual speed or VFD motors. This data contains some obvious errors. BUT, it looks like the VFD motors may be a little more efficient. However, the difference probably will NOT be large enough for you to notice on your power bill.

[mas985]

Which type of motor is more energy efficient (uses less KW or Amps to run a pool, Cost less)
VFD or ectro-mechanical hi-E 2-speed?

A VS will always be more efficient and cost less to run but it may not be enough to pay for the extra cost of the pump.

And does the ImPower have the same efficient as a VFD? The specs say that the ImPower has max 1.25 Output (1 HP up-rate) and 3 speeds (3450, 2600, 1725)

The ImPower would probably be more efficient than the same size two speed motor but not as efficient as a true VS. A VS has the ability to optimize the speed for the particular job, where as the IMPower is a fixed three speed, so there is less flexibility.

The cost savings for any of these options will depend on how the pump is used. With solar, you will be using the pumps at high(er) speed most of the time so may see only a small change in your power bill. However, the VS would allow you to set the speed for just enough flow rate to keep the vacuum release closed and minimize energy use.