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Thread: Two pumps better than one?

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    Two pumps better than one?

    Sorry if this has been posted.....I searched and didn't find this subject. I've seen multiple pumps run in parallel (4 pumps suction going to 4 pumps discharge to the pool) but I've not seen anyone that has run them in series....meaning run a 1000 gph discharge into the suction of a 1500 gph and then to the pool. I worked in a chemical plant for nearly 30 years and in certain instances you could get more pressure that way and it was better on the pump. Just wanted to check if anyone had done this.

    Before you ask, I have a 1000 and am thinking about upgrading to the 1500 and the preceding thought entered my mind. My wife would say I had too much time on my hands.....not so, I thought of the idea while walking and chewing gum at the same time. Thanks in advance for your answer(s).

    MDB in SE La

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    4JawChuck's Avatar
    Join Date
    Jun 2010
    Winnipeg, Manitoba, Canada

    Re: Two pumps better than one?

    There is no advantage with staged centrifugal pumps, in what circumstances did you see staged centrifugal pumps? If you need pressure to overcome head or distance, a positive displacement pump is the better choice neither of which is an issue with a pool or tub.
    55 Kilolitre in-ground 18'X36' vinyl lined kidney shape, 1HP pump, Jacuzzi 250lb sand filter, RayPak Delta T 200K BTU natural gas heater. New PoolWerks "Blue Diffusion" liner on May 26th-2011
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    Join Date
    May 2010
    Dallas TX

    Re: Two pumps better than one?

    I have a screwy system with 1 outlet of main 2.25hp pump -> second 1hp pump ->SWG -> floor system, with the other outlet going to the jets. The PO did this when the SWG was installed. When both are running, the jets barely trickle while the floor system goes great guns.

    I just run the big boy alone now. Later, will re-plumb to put in parallel, and only just the small one for longer time periods. the big boy will be in reserve in case more flow for vacuuming or whatever is needed.

    Centrifugal pumps generally put out a given head in a given installation. What are you trying to do with moving to a bigger pump? An efficcency gain (and cost reduction) can be had by going to a larger, 2spd motor and running on Low.

    33k Gunite, CompuPool CPSC48 SWG, Sta-Rite System 3 DE, 2.25hp dual-speed, POOLVERGNUEGEN Pressure-side

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

    Re: Two pumps better than one?

    In normal residential setups you do not want to run more than one pump at a time (expect for booster pumps for pool cleaners, or separately plumbed pool and spa pumps).

    Running pumps in series is tricky and requires special plumbing. You can run pumps in parallel, but this is normally only done with matched pairs of pumps to produce very high flow rates. Parallel setups are prone to problems when the pumps are not matched.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Two pumps better than one?

    OK thanks for the info, I kinda figured there wouldn't be any advantage. The times that I used two pumps in series was at a chemical plant and they were engineered to pump the liquid that was pumped. Pumping water certainly isn't rocket science but just wondered if by chance someone did it and the results.

    Thanks for your help. This is a really great site and I'm back to browsing.
    Again, Thanks.
    MDB in SE La

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    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA

    Re: Two pumps better than one?

    Theoretically, putting pumps is series can double the maximum head which is why boosters pumps are put in series with the main pump but other than that there really isn't a need to put pumps in series except for perhaps a solar installation on top of a 10 story building.

    Putting pumps in parallel with double the theoretical maximum flow rates although plumbing head loss becomes a much bigger factor in this mode unless that is doubled too.
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