EVSJ3 Variable speed motor replaced single speed motor

[BobFields]

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.

 

[JasonLion]

Welcome to TFP!

A higher SFHP motor is always fine in an existing pump. SFHP is SF times HP, both should be listed on the plate on the old motor. You went up enough in HP that the SFHP should be just fine, even if you can't double check.

 

[BobFields]

Thanks. The old motor was SF 1.0 1.5 HP 3450 RPM single speed. Rusted out on the bottom after 10 years. I've read that the biggest factor for determining power usage is the impeller (and total resistance / pump head) rather than the motor HP.

The only other concern is that when operating at lower speeds the strainer basket (at the pump impeller) is only about halfway full of water when operating about 30-40% speed. The flow through both the chlorine generator and roof solar heater is still adequate at this flow, no cavitation or bubbles coming out. I assume there are no ill effects on the pump as long as the impeller intake is still covered in water? I'd like to run as slow a speed as possible as much as possible, for energy savings. I have to run at 75% or higher to get the basket to fill with water. The pump primes very well when starting up, less than a minute to completely fill. No leaks on the input suction side that I can see, just lower suction pressure. I guess I could always upgrade the impeller if I want more flow, I assume I can put a more powerful impeller in the same Super-II housing, not having to replace the entire pump side?

Thanks so much for the answer.

 

[JasonLion]

That is fairly common for variable speed pumps. As long as the water level stays above the intake port you are fine.

Yes, you can upgrade the impeller if you want. The only other part that will need to be changed at the same time is the shaft seal. However, nothing you have said indicates any need to do so.