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Thread: Pump too big for pool, read some posts on reducing flow with ball valve

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  1. #1
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    Default Re: Pump too big for pool, read some posts on reducing flow with ball valve

    Quote Originally Posted by nicole12
    I've read some posts on a temp. solution to restricting flow for a pump that's too big for a filter, but there are different views on where to place that shut-off. I have a ball valve coming from the skimmer to the pump, could I shut some of the water off at that point or do I need to install another ball valve at a different location.

    I have an Astralpool 1.5hp single speed pump and a 150lb AstralPool Sand filter. I believe my filter says 35-60gpms and from I've read on the info for the pump could be anywhere 98-30gpms depending on the feet of head, which I have no idea what that means. Pool is only around 7500 gallons. Don't know why they set me up with such a high powered filter but at this point I don't want to spend the money on a new pump.
    Actually the ball valve WOULD solve the problem (eventually) as it would lead your pump to a VERY early grave and then you could put in a nice 0.5hp or so pump to solve the problem....


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    Default Re: Pump too big for pool, read some posts on reducing flow with ball valve

    Nicole,

    Actually, you can put the valve at anypoint after the pump. Head loss is additive and does not really matter where it occurs. Any restriction affects the entire flow path GPM so find an easy place to put it in the return path. However, if you place it after the filter, you can more easily adjust the flow by watching the filter PSI rise. You do not need to worry about pump damage as long as you keep the PSI rise to less than 10 and the total rise to less than pump maximum, usually 35 PSI but I would not exceed 25 PSI. Note that the restriction PSI is similar to puting solar in.
    Mark
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    Default Re: Pump too big for pool, read some posts on reducing flow with ball valve

    nicole,

    I don't know how much you pay for electricity, but I'm guessing that it's not cheap up there in MA.

    Considering the cost of the new valve being talked about and the unnecessary horsepower being used, you'll probably be money ahead if you replace the pump now.

    Of course, cash availability is always a consideration...

  4. #4
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    Default Re: Pump too big for pool, read some posts on reducing flow with ball valve

    When you throttle a pump on the discharge you lower its HP draw as well.

  5. #5
    Poconos is offline SuperMod Emeritus Whizbang Spinner Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars Poconos 4 stars
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    Default Re: Pump too big for pool, read some posts on reducing flow with ball valve

    Actually what is happening when you restrict the flow on the output side of the pump is to increase the pressure, reduce the flow, and thus reduce the work that the pump has to supply. The reduced work load, i.e. moving water, results in a slight decrease in power consumption. Opposite to what may seem intuitive. These comments apply to centrifugal pumps only, which all pool pumps are as far as I know. I agree that in the long run the cheapest option is to replace the pump.
    Al

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