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Thread: Best 2 speed pump option

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    Best 2 speed pump option

    Last summer my ancient 2 HP AO Smith Centurian pump started making a very, very loud noise, and our power meter started spinning at hyper speed! Our electrical costs soured by over 2x. A process of elimination (plus the obvious deafening noise) indicates to us that we need a new pump. The pump did survive the season, but each time I cleaned the pump basket I feared (or hoped!) it would not start.

    From reading this forum, it seems 2 speed pumps are usually recommended. We have relatively cheap power, and I don't know how how many more years we'll be living here. Point being, I suspect that VS pumps are unreasonable for me.

    What 2 speed pump would you recommend to replace our Centurian pump?? I have a 30K gallon IG vinyl pool, no extra stuff like waterfall or solar, and I have 2 strainers and 3 returns. Pump and filter are 20 feet from pool, and located about 2 feet above water level. I have a System 3 S7M120 filter.

    I'm looking to save as much money in operation and initial investment. Thank you in advance!
    32,000 gallon vinyl lined In Ground pool in central GA. No water features. System 3 S7M120 Cartridge Filter.

  2. Back To Top    #2
    Mod Squad zea3's Avatar
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    Re: Best 2 speed pump option

    Any 2 speed, 1-1.5 hp pump should be fine for your pool. Pentair and Hayward both make 2 speed pumps in that size.
    TFP Moderator
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    Vogue 21' round AG, Pentair 1 hp 2 speed pump, 36 sq ft DE filter, Hayward S180T 150# sand filter, Houston, Texas
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    Re: Best 2 speed pump option

    Thanks, Zea3

    Any pumps I should stay away from? Are there magnet based pumps I should look for, that would be recommended? Any particular features I should look for?

    Do some pumps have better lid removal options or better baskets? There are so many options on the market, I'm somewhat overwhelmed. Thanks for any specific recommendations or things to look for.

    Finally, I came across this site that seems to make a convincing argument for a VS pump, regardless of manufacturer. I'm sure he has an angle, but I'm not sure what it is.
    http://www.swimming-pool-information...eed-pumps.html

    Many thanks to the community for any guidance here!
    32,000 gallon vinyl lined In Ground pool in central GA. No water features. System 3 S7M120 Cartridge Filter.

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    mas985's Avatar
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    Re: Best 2 speed pump option

    AO Smith Centurion is a motor not a pump. The pump manufacture is different. One option is to just replace the motor with a two speed motor it would save you both time and money since it is a simpler installation.

    If you want to consider a motor change, please post a picture of your pump (not the motor).

    From the web site:
    I have installed many 2-speed pumps and have come to the conclusion they are an inefficient compromise compared to multi speed pumps for several reasons:

    1)Although they are less expensive,they require some type of automation to prime in high speed for a minute or two before going to low speed to prime. The automation devices can negate the cost savings.

    2)A two speed pump is about 1750 rpms at low speed...a multi-speed pump can run much lower.

    3)Even at the same speed,the permanent magnet multi speed pump is more efficient.

    4)The rebates from utility companies (up to 1000.00) usually only apply to multiple speed pumps.
    1) WRONG. A pump should not lose prime when it is shut off so it should not require re-priming every time it is turned off.

    2) True but sometimes, you can't operate at those lower speeds because the skimmer stops working.

    3) Only about 10% more efficient so not that big a deal.

    4) True again and it can make a big difference and cover the cost difference of the pump. So if you can get a rebate that pays for the cost difference, go for it.
    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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    Re: Best 2 speed pump option

    Thank you mas985!

    Really appreciate the reply and the details you provided. Makes perfect sense, and especially compelling on point number 1. On point 2, does the skimming really stop working if you go below a certain rpm? With my old pump, if I set the valve to wide open on the skimmers, the pump sucks the water out so quickly that sometimes it would empty the skimmer of water before enough water could refill it from the pool. It would then suck just a bit of air. I learned to keep the skimmer valve at 90% open, unless the pool was over full.

    I did not realize that the motor manufacturer was not the pump manufacturer! The wet side has no markings or branding as far as I can tell. Pretty sure the pump is about 15 years old. The wet area has started to "weep" on the fittings, so I think I'd better replace the lot.

    Finally, most of the two speed 1.5 hp pumps are designated as Above Ground pools. Should I disregard that? I'm not finding many labeled as inground pools at that speed and hp rating. Recommendations?
    32,000 gallon vinyl lined In Ground pool in central GA. No water features. System 3 S7M120 Cartridge Filter.

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    mas985's Avatar
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    Re: Best 2 speed pump option

    does the skimming really stop working if you go below a certain rpm?
    At some point, yes.

    Why do you need a 1/5 HP pump?

    This would work just fine for you.

    https://www.poolsupplyunlimited.com/...-pump/142954p1

    or this

    http://www.poolsupplyunlimited.com/P...pJIxoC36Lw_wcB


    But you do not want to use an AG pump on a IG pool unless the pump is self priming which most are not.
    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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    Re: Best 2 speed pump option

    Many thanks, Mark. Just what I was looking for. I did not realize that AG pumps are not usually self priming. That would have been a hard lesson to learn after installation! LOL. Appreciate that info.

    I think I'm ready to pull the trigger. Thanks again!
    32,000 gallon vinyl lined In Ground pool in central GA. No water features. System 3 S7M120 Cartridge Filter.

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    Isaac-1's Avatar
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    Re: Best 2 speed pump option

    I have a similar size pool to yours with a 2 speed 1.5 HP Jandy Flo-Pro pump that I am mostly happy with, only thing I don't like is the basket design as I tend to whap my knuckles when it gets stuck, also the basket o-ring needs to be lubricated often.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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