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Thread: Replacement Pump for 12,700 gal Inground Pool

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    Replacement Pump for 12,700 gal Inground Pool

    Hello all. After trying to muddle through spreadsheets and opinions to create my own... I'm lost. So I'll just throw it out there.

    I moved into a TX house four years ago with the following set up:
    12,700 gal Inground Pool
    Pentair DE Filter
    Speck 433T 1 1/2 HP Pump
    Polaris 360
    Waterfall
    The filter/pump set up sits about 2' below the water level and 20' away from the near edge of the pool

    The pump bearing sounds like it's been getting worse over the past year (more and different sound/noise) and a seal is leaking, not a lot but probably 2-3 gallons/day running the pump 8 hours/day.
    Since it looks like a pump replacement, I've been looking to move to something more efficient but affordable. Have narrowed my choice to Pentair Whisperflo or Superflow Dual Speed 1 or 1 1/2 HP, or maybe the EcoPump EP-4 or EP-6 (I have to admit the idea of having my water moving all the time is appealing).

    My questions:
    Is 1 1/2 HP more than I need?
    What's the difference between Up Rated Efficiency and Full Rated Efficiency on the Pentair pumps (WFDS-24 vs WFDS-4)?
    I'm not looking to have the Cadillac of Pool Pumps, so VS is probably not where I'm going. Am I missing something? I see mixed reviews on EcoPump, but their EP-4 looks awfully inexpensive to operate with fewer fail points than some other uber efficient pumps.

    Thanks in advance.

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    JasonLion's Avatar
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    Re: Replacement Pump for 12,700 gal Inground Pool

    The EcoPump cost comparisons on their web site are misleading. They use actual current draw for their own pump, and rated maximum current draw for all of the other pumps. Since actual current draw is way less than rated maximum the comparisons are meaningless.

    When comparing pumps you need to understand that rated HP is not comparable between pumps, one 1 HP pump might move far less water than another. The WhisperFlo pumps are much larger than their listed HP indicates, while the SuperFlo pumps are smaller. SFHP is more indicative of the actual size of the pump. SFHP = HP * SF. Terms like up rated and max rated give you hints about what the SF is going to be, but the terms are not used uniformly, so it is better to compare SF directly if possible.

    Another thing to understand is that smaller pumps use less electricity than larger pumps to move the same amount of water. One way to get a "smaller" pump is to get a two speed pump and run it on low speed. Running on low speed a two speed pump will move half as much water and use one quarter as much electricity doing it, so a 50% savings to move the same amount of water.

    For circulation you only need a small pump. However, you have a waterfall. To make the waterfall work correctly you may well need a pump as large as your current pump. Here is another place a two speed comes in handy. You can run on high speed when running the waterfall, and on low speed when just circulating and filtering water.

    So one step is to lookup the SF rating of your current pump, so you can find a pump of comparable size so the waterfall will look correct. Another step is tell us your electrical rates, so we can get an idea of how much advantage you will get from running a super high efficiency pump vs a plain two speed pump.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Replacement Pump for 12,700 gal Inground Pool

    Thanks much for the perspective. My electrical rates are .093/kwh-- much lower than what the mfgs use when comparing cost savings. Looking at SF (Service Factor?), it looks like a lower number is more beneficial? Is that correct. My current pump, out of production and best I can tell, has an SF of 1.3. A Pentair WFDS-4 (1 hp) is 1.65, a WFDS 24 is 1.25. I don't know how to compare those if you can shed any more light on that.

    Thanks again.

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    sargent's Avatar
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    Re: Replacement Pump for 12,700 gal Inground Pool

    If you are just replacing your motor, what you have is 1.5 hp x 1.3 = about 2 total hp (also called SFHP), so you need to get a motor with at least 2 total hp. So, you could get a 2 hp motor with SF=1.0 or some other combination that yields the correct total.

    If you are replacing the whole pump, you could look at the pump curves. Although your pump is out of production, it might be close to the Speck 433-IV, which is 1.5 hp and 1.3 SF (or 2.0 hp with SF of 1.0). The flow at 50 foot of head for that pump is about 80 gallons per minute. The comparable Pentair Superflo 2 speed pump is the SF-N2-2A, which is 2 hp with 1.1 SF. If you could do with a little less flow for your waterfall, you could get the SF-N2-1-1/2A, which is 1.5 hp with 1.1 SF.

    In the Whisperflow series, the WFDS-4 or the WFDS-26 would have a flow that is more than your present pump, while the WFDS-3 or WFDS-24 would have flow that is less than what you have now. The WFDS-4 and WFDS-26 are essentially the same pump. Also the WFDS-3 is the same pump as the WFDS-24.
    14k gal IG vinyl, Jandy Flopro 1 hp up-rated, 2 spd pump, Hayward 325 sq ft cartridge filter, Circupool Si-40 SWCG

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    JasonLion's Avatar
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    Re: Replacement Pump for 12,700 gal Inground Pool

    It doesn't make any difference if SF is low or high, all that matters is the SFHP number.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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