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Thread: Upsizing motor on exiting pump

  1. Back To Top    #1

    Join Date
    May 2010
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    Upsizing motor on exiting pump

    Have a Pentair Whisperflo WF-26, 1.5hpx1.1sf. Long story short, I'm pushing about 65gpm on a clean filter, in a ~32k gallon pool. I've probably got some fairly restrictive plumbing (and a 6-way multiport) and would like to push more water- not to turn it over quicker, but to get more actual "circulation"- without my Polaris running, whenever I get some "stuff" in the pool, it just sort of sits there. I can't do anything about the plumbing, number of returns, etc. (though I've thought about running a switched bypass around the multiport as well as the heater)- so I'd like to upsize the pump. Particularly, I've got a 2-speed 2x1.1 hp motor hanging around with a square flange that should mate up- but a few concerns-

    1) going from 1.5 to 2- is that too much of a change for the pump impeller?
    2) with a non-matched impeller, would I be getting more or less flow than I'd expect (guessing less)?
    3) is this a bad idea from the get-go?

    Thanks!
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
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    Re: Upsizing motor on exiting pump

    1/2)You will move the same amount of water with the 2HP on the 1.5HP impeller. You would have to get a bigger impeller to move more water.
    3) Yes, sort of.

    The bigger pumps will just use more electricity ... and if you are going to use the low speed to save $, well, then you are running a lower flow rate than you are now. What I would actually consider doing is putting the 2HP 2-speed on the existing impeller and running on low speed most of the time as that will save you money on electricity.

    One option to help circulation would be to put smaller eyeballs in the pool returns so you get more velocity in the flow.
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  3. Back To Top    #3

    Join Date
    May 2010
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    Dallas, TX
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    Re: Upsizing motor on exiting pump

    Thank you- and never thought about going with smaller eyeballs.

    I'd never use the low speed except in winter, especially when it forces on when temps get very low- I'm fully expecting to spend more on electricity to get greater flow.
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

  4. Back To Top    #4

    Re: Upsizing motor on exiting pump

    Do your skimmers have weirs (doors)? They make a huge difference in the amount of surface action the pool gets. Also, if the skimmers have open equalizer lines (a hole in the bottom of the skimmer that connects to the pool wall), then that will reduce your surface action.

    Cutting back on the main drain can also help increase skimmer action. When you look into the skimmer, you should see fairly quick water flow on the surface.

    If you get good results with your Polaris, then you might want to run it twice a day for about an hour per run on a timer.

  5. Back To Top    #5

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    Re: Upsizing motor on exiting pump

    Yup- two skimmers and both have weirs. I got a heck of a lot more flow through the skimmer closer to the equipment than the other (the whole thing was leak-checked 2 years ago when we moved in), probably an easy extra 30ft to the far skimmer. No equalizer lines.

    I can shut off the main drain suction independently- will see if that reduces flow (have a flowmeter installed) or if it will just pump greater flow through the skimmers.

    Polaris already runs whenever the pool is running which is 8 hours/day (~1 full turnover in an ideal world). Could it run longer? Probably.
    30k gallon IG PebbleSheen refinished 2014
    60sqft FNS Plus DE wih Proguard Cellulose, 1.5hp 2speed WhisperFlo
    TFTestKit and Stenner fixed 10gpd on timer with bleach
    Dolphin m500

  6. Back To Top    #6

    Re: Upsizing motor on exiting pump

    As jblizzle noted, a 2-speed motor might be your best bet. Run 8 hours a day at high speed and the rest at low. When your pump is off, you're not getting any circulation at all. I think that this would be a better idea than a larger pump.

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