I replaced a 1.5 HP single speed motor with a 3 HP variable speed motor last week, keeping the existing Hayward Super-II pump. Everything seems fine, looking forward to the power savings. The SWG and even the solar heater on the roof run fine (adequate flow) even down to 30-35% flow (as low as it goes), I need to run about 50-60% flow for the pool sweep and surface skimmer to work well but those don't need to be on all the time.I ran the previous pump between 5-9 hours/day depending on the season, 12 months. Even at 100% flow it runs much much quieter than the old pump and probably uses less energy. Both pumps were 3450 RPM.
I picked a 3 Hp because the specs said it could replace any pump from .5 to 3 HP, and I heard stories about the variable speed pumps being underpowered compared to the single speed (not true in this case), and the 3 HP was the same price as the 1.5 HP variable speed pump (about $400 plus seal). The other model motors were all about $200 more, and I figured they were all made by US Motors anyway so similar reliability and warranty. I kept the existing pump (Hayward Super-II) which I believe was sized for 1.5 HP. I expect to spend a while adjusting the speed programs to optimize power usage, and also adjusting the generator and solar and pool sweep usage.
So - anybody have experience or tips/advice with the EVSJ3-NS? Or replacing single with variable speed, of different HP, keeping the old pump/impeller? Seems pretty good so far.