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Thread: Downgrading from a 3/4hp to 1/2hp Hayward super pump

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    Downgrading from a 3/4hp to 1/2hp Hayward super pump

    Hi all,

    FIRST POST!!! I bought this house a couple years ago and I've only opened the pool this year. Big learning experience and in the few months I've been reading TFP I feel I've learn enough to be able to manage this myself (and make some improvements!!!).

    After starting her up for the first time I've learned all three major components are "broken":

    1) STA-RITE sand filter leaks sand into the pool (bought a used hayward 21" model, working great)
    2) Propane Laars heater leaks at the copper pressure switch line (bought a hayward H250C1 NG heater)
    3) Hayward Superpump 3/4 water pump shuts off after 10 minutes of usage - overheats.

    To address #3, a friend of mine gave me a like new 1/2 hayward super pump. The 3/4 hp pump works ok if I have a fan blowing air onto the rear, but on warmer days it still overheats. That, and it's old and consumes more energy than a 1/2hp pump. My question is can I safely downgrade? There are two returns on the pool with no water features. Each return is no more than twenty feet from the pump, but there are a significant amount of 90" bends in the 1.5" tubing.

    Is a 1/2hp pump too small alltogether? How would I know? Would it make sense to remove all the rigid 90's and move to that softer supple white plastic hose? I'm curious as to how much of a restriction 90's add to your flow. If pictures would help I'm more than happy to snap some. I have no problem doing any of this work but would like to know in advance if there is any advantage before I start unbuilding stuff :0

    Thanks in advance, this is an incredible forum and I really look forward to contributing once I'm more familiar with my own setup.

    14"x24" 6" deep IG vinyl kidney pool.

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    Re: Downgrading from a 3/4hp to 1/2hp Hayward super pump

    Only real issue with the downgrade is how many GPMs the smaller pump will put out, and is it enough to turn your pool over in a 24 hr. period. I suspect it is more than adequate for your size pool, and wouldn't bother with changing the piping configuration just because.

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    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Downgrading from a 3/4hp to 1/2hp Hayward super pump

    I'd just stick the ½hp pump on there and let it run. You'll know soon if it's not big enough. I seriously suspect that it will be fine.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/hp 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: Downgrading from a 3/4hp to 1/2hp Hayward super pump

    Well I did the math and my pool has 13,000 gallons which, to turn over every 12 hours will take a pump that can flow 18GPM.

    Hayward tells me that even at 40" of head the 1/2hp pump can still do 29GPM.

    I know all the math tells me I'm more than in the clear, but I'm looking for real life experience, will this affect my pools ability to distribute the heat effectively? I have a 250k BTU heater which I think is totally overkill. Seeing as how I only have two returns, will I be under utilizing my heater? (ie. heat the water more than I'm able to flow it?)

    Thanks again!!
    14"x24" 6" deep IG vinyl kidney pool.

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    Melt In The Sun's Avatar
    Join Date
    Oct 2009
    Tucson, AZ

    Re: Downgrading from a 3/4hp to 1/2hp Hayward super pump

    Our resident pump guru (mas985) has a 1/2 HP two-speed pump on his pool, which is bigger than yours. He even runs solar with it. Yours will be fine.
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
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    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA

    Re: Downgrading from a 3/4hp to 1/2hp Hayward super pump

    Technically, my pump is really a 1/2 HP full rated Northstar and has about the same head curve as the 1 HP uprated Superpump (sp2607x10). The 1/2 HP uprated Superpump (sp2600x05) has much lower head curve than my pump but it still should work fine for general circulation.

    I don't know much about your setup but assuming 50' runs of 1 1/2" pipe and all the fixings, here is what you might expect with your old and new pump. This is only an estimate and depends on your actual plumbing setup.

    3/4 HP Superpump - 40 GPM @ 41' of head
    1/2 HP Superpump - 35 GPM @ 33' of head

    So you would only be lossing about 5 GPM or less than 10%. But that 10% loss in flow rate will likely get you about 25% in energy savings.
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner

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