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Thread: Is my pump too big?

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    Turbota's Avatar
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    Is my pump too big?

    I just purchased a 10 year old house with pool here in Florida.

    Pool Type:
    In-ground concrete with no spa or water features

    Pool Capacity:
    9,000 gal.

    Pump:
    Sta-Rite Max-E-Pro

    Pump Motor:
    1 HP single speed

    Filter:
    Pentair Clean and Clear 100 sq. ft. cartridge type

    Minimum Pipe Size in System:
    1.5"
    __________________________________

    Since the water pipes are only 1.5", I read that this pipe diameter limits water flow to 42 GPM. Even though both my 1 HP pump and my Pentair filter is capable of flowing greater than 42 GPM, I am still limited do to the 1.5" pipe size.
    At 42 GPM (2,520 GPH), it should only take 3.6 hrs to turnover all the water in my 9,000 gal pool.
    __________________________________

    Here is my question ... Am I right in thinking that a 3/4 HP motor with a properly sized pump impeller would also be capable of flowing 42 GPM? ... If so, using the 1 HP single speed pump motor I have now serves me no advantage over a 3/4 HP single speed motor other than a larger electricity bill.

    BTW ... I was thinking that a 2-speed pump (while advertised as using less electricity) might not save that much more money since when it operates at the lower speed, it will just need to run for a longer time in order to turnover all the water ... and there goes the savings

    Thanks,
    Ron
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    JasonLion's Avatar
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    Re: Is my pump too big?

    Quote Originally Posted by Turbota
    Since the water pipes are only 1.5", I read that this pipe diameter limits water flow to 42 GPM.
    That isn't the way it works. 42 GPM is a guideline for the maximum amount of water you should try to move through a 1.5" metal pipe to avoid damage to the metal. There is no such restriction on PVC pipe, which won't wear away the way metal pipe does. Regardless of the pipe type, if you put a large enough pump on it you can move far far more water than that through the pipe. Still, 42 GPM is a nice guideline for when smaller pipes start to get noticeably inefficient. There isn't a sharp dividing line, and running 50 GPM will still be fine, but the higher you go the more energy you are wasting to friction.

    Quote Originally Posted by Turbota
    BTW ... I was thinking that a 2-speed pump (while advertised as using less electricity) might not save that much more money since when it operates at the lower speed, it will just need to run for a longer time in order to turnover all the water ... and there goes the savings
    A two speed pump running on low speed moves half as much water while using one quarter as much electricity. Even after taking into account that you need to run it for twice as long, it still uses only half as much electricity.

    Getting a two speed motor would have a far far larger impact than switching to a 3/4 HP pump. Doing both is also fine as long as you don't have any water features, but two speed 3/4 HP pumps are difficult to find.

    One other consideration is that replacing a working pump is only worth doing if your electric rates are very high.
    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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    Turbota's Avatar
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    Re: Is my pump too big?

    Jason ... thank's a bunch for the info you provided, especially about setting me straight about the pipe diameter info.

    Just, so I am straight about this ... Do you think my system with the 1 HP pump motor is realistically running at about 42 GPH, or more close to 50?

    Do you think a 3/4 HP single speed pump will flow just about as much as I am getting now with the 1 HP pump, or will it be much less?

    Thank's,
    Ron
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    mas985's Avatar
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    Re: Is my pump too big?

    The label HP is really not enough to characterize a pump. You might have an up rated or full rated pump. Do you have a pump model # (not motor)?

    A 1 HP up rated pump will have different performance than a 1 HP full rated pump but it should be in the range of 60-80 GPM range (not GPH).
    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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    Turbota's Avatar
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    Re: Is my pump too big?

    Mark ... The pump is a:

    Sta-Rite P6RA6E-205L Max-E-Pro
    Single Speed Up-Rated 1 HP Motor
    115V/230V
    http://www.poolsupplyworld.com/Sta-Rite ... E-205L.htm

    The pump and filter are located about 40 feet from the center area of the pool and the smallest pipe diameter in the system is 1 1/2"

    The 9,000 gal. pool has:
    1 main drain
    1 skimmer basket
    3 return jets along the sides about a foot below the water level
    and a suction inlet fitting that you can attach the hose for the suction cleaner (Zodiac MX8)
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    mas985's Avatar
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    Re: Is my pump too big?

    I would put the flow rate somewhere around 60-70 GPM. The pump you have is the same size as a full rated 3/4 HP so you really don't have a big pump. Downsizing one size would get about 10% more in efficiency and lose about 15% in flow rate (~50-60 GPM). But takes quite a while for 10% efficiency to pay for itself. You would gain far more with a two speed.

    Also, don't get too hung up on turnover. Just run the pump long enough to keep the pool chlorinated and clean.
    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: Is my pump too big?

    Thank's
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    Re: Is my pump too big?

    I wouldn't bother with a new pump until the old one is broke - then I would think about the 2 speed / lower HP pumps. Yes, you can gain some on effiecency, but is it really going to pay off in a reasonable amount of time ?
    16x32 IG 19,000 gallons, Pentair 1.5 hp Energy Efficient Superflo pump (348024),vinyl liner, Chlorine dispenser, Hayward S-244T sand filter

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    Re: Is my pump too big?

    Turbota, personally I think you would be well served if your really trying to figure this out that you KNOW what your exact flow is by installing a flow meter? You can go cheap or you can go expensive. That way you will know your exact numbers, you will be able to tell more exactly when the filter is getting clogged thereby reducing flow.

    And I so agree with scooperhsd, unless your pump is broke or electricity rates go up, I wouldn't switch. I would think the $100 bucks or less for a "manual" flow meter would be money well spent so you have exact flow numbers you can examine so there will be no guessing about anything anymore. Plus, one day in the future when you do replace the pump, the knowledge of exactly how the flow rate changes with a two speed setup would be priceless.

    Bob E.

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    Mod Squad jblizzle's Avatar
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    Re: Is my pump too big?

    "Exact" is pretty misleading taking about flow rates. Many of the meters are only accurate to +/-10% of the max flow rate. A common meter goes up to 100 gpm, so your "exact" flow rate is really +/-10 gpm which is significant for typical pool flow rates.

    The newer meter that looks like a check valve is supposedly better, but we have yet to see any real life reports.

    Posted from my Droid with Tapatalk ... sorry if my response is short
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    mas985's Avatar
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    Re: Is my pump too big?

    Plus knowing the exact flow rate is not all that important even when sizing a pump for a pool. The only time it helps is if you are trying to size a pump for a spa. But even then, there are other ways to size a pump.

    However, I would agree that the savings for a two speed motor can be somewhat muted if your energy rates are fairly low. It will take quite a while to pay off the new motor.
    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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    Turbota's Avatar
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    Re: Is my pump too big?

    Thank's everyone for all your help ... I have just one more question concerning a Standard Efficiency pump vs an Energy Efficient pump, but I won't 'muck-up' this thread anymore, so I will just start a new one.

    Ron,
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    JasonLion's Avatar
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    Re: Is my pump too big?

    Please keep everything together in one thread if the questions are at all related.

    Energy efficient pumps use motors that are about 10% more efficient than regular pumps with otherwise matching specs.
    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: Is my pump too big?

    Ok

    I have a question concerning a Standard Efficiency pump vs an Energy Efficient pump. Both pumps shown below are 1 HP single speed pumps made by the same manufacturer:

    Pentair SuperFlo 1 HP, Standard Efficiency, Model 340038
    Speed: Single
    Voltage: 115 / 230V
    Full Load Amps: 14.2 / 7.1
    Service Factor: 1.25
    Cost: $322
    ___________________________________

    Pentair SuperFlo 1 HP, Energy Efficient, Model 348023
    Speed: Single
    Voltage: 115 / 208-230V
    Full Load Amps: 11.2 / 6.0-5.6
    Service Factor: 1.25
    Cost: $369
    ___________________________________

    Even though both pumps are 1 HP, notice the Full Load Amps are lower on the Energy Efficient pump.

    And, even though both pumps are single speed, the Energy Efficient pump shows 3 Voltage numbers vs only 2 Voltage numbers for the Standard Efficiency pump .... Also the same for the Full Load Amps (not sure why that is)?

    With only $47 difference in price between the 2 pumps, do you think the electricity cost savings of the Energy Efficient pump would make up the difference in price fairly soon?

    Ron,
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    Re: Is my pump too big?

    As I said the energy efficient pumps are about 10% more efficient, so use about 90% of the electricity. How much that saves you depends on how much you run the pump and what your electric rates are. In most situations they will pay back the additional cost in a reasonable amount of time.

    The motors are different, and several of the listed specs come from the motors. In this case the motors probably come from different manufacturers who list their specs differently and Pentair probably just copied them from the motor manufacturer.
    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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    Turbota's Avatar
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    Re: Is my pump too big?

    Ok ... thank's Jason
    9,000 gal. in-ground concrete pool
    Sta-Rite Max-E-Pro pump and motor (1 HP)
    Pentair CC100 cartridge filter (100 sq ft)
    Zodiac MX8 suction pool cleaner

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    mas985's Avatar
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    Re: Is my pump too big?

    EE pumps tend to be single speed so that will use much more energy than a standard efficiency two speed pump on low speed. The only advantage to an EE pump over a two speed is when running on high speed which should be small.
    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: Is my pump too big?

    Yes - I got the Energy Effieicnet single speed instead of the standard single, but knowing what I know now - I would have gotten the 1HP 2 speed instead. However - I'm not getting rid of my current pump until ... . And even then - I have a 3/4 HP Hayward PowerFloII That I'll probably use up first before buying a new pump. It seemed to handle my pool just fine for 2 weeks while I was inbetween 1.5 HP pumps.
    16x32 IG 19,000 gallons, Pentair 1.5 hp Energy Efficient Superflo pump (348024),vinyl liner, Chlorine dispenser, Hayward S-244T sand filter

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