Pump sizing and variable vs two speed decision

[MNiels]

Our motor just died and we felt it would be a good opportunity to upgrade. We've gone through the calculations for feet of head and are more confused than ever. We currently have a 23,100 gallon pool with a Pentair Pinnacle pump and 1.5 hp AO Smith Centurion motor (dead) which runs (ran) at 3450 rpm. Is there a simple way to estimate what size variable or two stage pump would work for our situation? We have about a 75' run of plumbing to both the main drain and the skimmer. An online customer service person at a very reputable online company told us that we needed a 3 hp variable speed pump. Also, with no water features, heater, fountain, etc., would we benefit from a variable speed over a two speed pump, or even another single speed, pump? Thanks all!

 

[mknauss]

From an electrical usage standpoint the VS or 2 speed will be the least. As long as you can run the 2 speed on low most of the time there will be a significant $$ savings on electricity. The 2 speed is much less upfront cost than the VS. And you most likely only need the motor, not the wet end.

Call INYOpools and ask them what 2 speed motor would match your wet end.

Take care.

 

[mas985]

With your setup, the "size" of the pump does not need to be very big. In fact, the smaller the better for a two speed. For VS, you can go with any pump you want. A VS will save a little more in energy costs over a two speed but costs more upfront. If your power company gives rebates for VS pumps, that can tilt in the favor of a VS.

 

[jay jay]

I just went through this with my failing motor. I would suggest you download the pump spreadsheet from mas985's signature.

You can compare different pumps on your pool and electrical usage / cost based on runtime and speed. You can also enter the purchase price and see how long the payback will be.

 

[MNiels]

Thank you all for the valuable input. Went with a Pentair (Sta-Rite) SuperMax VS pump and decided to have it professionally installed. Happy with it so far but it's only been a day.