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Thread: SWG with a 2 speed pump

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    SWG with a 2 speed pump

    All, I am replacing my 2 hp single speed pump motor due to a bad bearing. (I was going to just replace the bearing but during the motor surgery I realized how bad the motor was and decided to just replace it) I have a SWG and want to go to a 2 speed to save on energy costs. Are there any issues with running the pump on low speed with the SWG? Also, I am assuming I do not have to change any of my pump parts if I purchase a direct replacement motor with the only change being 2 speed.

    15k gallon, gunite pool with SWG and cartridge filter (just bought house so dont have any particulars on the filter or SWG yet)

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    DaveNJ's Avatar
    Join Date
    May 2007
    Toms River, NJ

    Re: SWG with a 2 speed pump

    I run mine on low speed most of the time. Do have to set valves so there is sufficient flow at the SWCG. Once its set I don't change the valve positions often. Marked the valve positions so I can return them to the normal every day use position.
    Can't give advice on the motor replacement.
    IG 18x36 oval vinyl, Spill over spa, Northstar 2hp-2spd, 2.5" piping, S310T 500lb Sand filter, 400k gas heater, AutoPilot SWCG

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    spishex's Avatar
    Join Date
    Oct 2008
    Hillsborough, NC

    Re: SWG with a 2 speed pump

    If you are matching the motor's HP and SF you're ok. If you get a lower HP with the same SF you'll need to downsize your impeller. If you get a higher HP motor you can use the same impeller but will get no benefit from it. Long story short: your impeller size is matched to your motor size.

    Assuming you get the same HP/SF motor then you'll need a new shaft seal and you might consider new housing and diffuser o-rings depending on your pump.

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: SWG with a 2 speed pump

    The SWG needs some minimum flow rate to work correctly. Most of them will turn off automatically if they aren't getting the flow rate they need. Given that you have a 2 HP motor, it is quite likely that you will have a high enough flow rate on low speed. The actual flow rate depends on many details of your plumbing and how dirty the filter is, so there is a small chance you will not get sufficient flow.
    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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