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Thread: WhisperFlo Motor Replacement - Need help sizing impeller

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    WhisperFlo Motor Replacement - Need help sizing impeller

    Hello all, I am new to both these forums and to pool pumps in general.

    My WhisperFlo 2 HP WFE-8 motor needs replacing, and I decided to switch to a 2-speed replacement: Pentair 071320S. (Specifics about my pool setup are in my signature). My plan is to run on low speed 24-hours a day and manually switching to high speed during cleaning (and possibly during solar heater use, if needed).

    My confusion starts with whether or not the 071320S is a SuperFlo or a WhisperFlo. Reading through Pentair's web site, it looks as though 071320S can be used for both pumps? Is this correct? Also, I sometimes see the 071320S sold as a 1.5 HP, and sometimes as 2 HP motor. Does this depend on whether it is being used as a SuperFlo (2HP) vs WhisperFlo (1.5HP)? Or is it just a matter of using a different Impeller?

    Assuming that the 071320S can act as a WhisperFlo motor replacement, should I 'downgrade' my Impeller from the WFE-8's 2HP version to a 1.5HP Impeller (or even 1HP Impeller)? My initial calculations for GPM I would need are ~22 GPM if running 24-hours per day, up to 73 GPM maximum based on my plumbing (my numbers may be off; I'm new at this). Looking at the WhisperFlo performance curves it looks as though 1.5 HP would be sufficient, however I am concerned about providing enough power to utilize my roof solar heater.

    Any help in demystifying all of this would be most appreciated!
    17k IG Vinyl pool, WhisperFlo 2HP WFE-8, Jandy CL340 Cartridge Filter
    200 sqft Fafco solar panels, Taylor Test Kit K-2006

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    Mod Squad Bama Rambler's Avatar
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    Re: WhisperFlo Motor Replacement - Need help sizing impeller

    Welcome to TFP.

    The Pentair 071320S is a full rated 1½ hp motor and the WFE-8 is a 2 hp full rated pump. In order to use the 071320S you need to down size the impeller to a 1½ hp model. I don't know if you have to replace the volute as well.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Re: WhisperFlo Motor Replacement - Need help sizing impeller

    According to Pentair's website, the volute looks the same for all models. Also the diffuser should match:
    13 072927 Diffuser assembly, WFE-2–8, 1/2 HP – 2.5 HP

    I have seen warnings that when replacing a pump motor you should match the original HP. However, it feels like the previous owner installed an over-powered pump for the system. Will 1.5HP be enough for my needs? It sounds like the only part I need to replace (beyond the motor) is the 1.5HP Impeller, effectively converting my pump into a WhisperFlo WFDS-6?
    17k IG Vinyl pool, WhisperFlo 2HP WFE-8, Jandy CL340 Cartridge Filter
    200 sqft Fafco solar panels, Taylor Test Kit K-2006

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    mas985's Avatar
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    Re: WhisperFlo Motor Replacement - Need help sizing impeller

    The only thing you need to change when downsizing an impeller is the impeller and a new seal. The existing motor can support a smaller impeller but not a larger one.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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