Hey Mas...thanks for chiming in.
Some of the calculations--like all math for the most part--gives me tired head!!!
But your explanation definitely helps.
So in the big picture, either the high flow or the high pressure should provide very similar results. I pulled the curve charts from the pentair site for both models and pasted them side by side for comparison. When I take my assumed head of about 45 and the gpm rate at 45 (1.5" return line), they land on the same thing on both charts--dead on and dead center of the efficiency curve line for the 3/4hp uprated or 1/2hp full rated.
I kept thinking to go high flow over high pressure because all the HP information kept mentioning need for this with floor cleaners, heaters, high head, etc. But I have none of that--return comes out of the filter, through a rainbow chlorinator, through a 2" to 1.5" reducing bushing (to size pad equipment to return line) and back to pool.
So, as usual, I am probably WAY over thinking this decision! Maybe the fact that the high pressure can be had immediately and almost anywhere and the high flow is difficult to find, should have been a clue that MOST people, new pools or old, are putting on the HP version and the HF version is reserved for waterfalls, etc.
And, yes, I considered a two speed pump but dropped that thought for a number of reasons. First, my pump always has been a 1.5hp--way overkill I am now learning. So my recalculation has me best suited for a 3/4hp. Since I am cutting power consumption nearly in half with that, I do not think my savings with the two-speed at new 3/4hp size would be much more. Now, if I was replacing with 1.5hp, yes a two speed would definitely be the choice.
Also, since I am sizing to what is proper, I have concern that my low speed might be so low that I will hardly use it. Finally, going two speed will bring up additional thought on my control system. I am already dropping nearly a grand on new filter, valve, and pump, not sure I am ready to spend more money to upgrade the control timer.
Thanks...Paul
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