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Thread: Pump Losing Prime

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    Pump Losing Prime

    I just installed a Pentair 342001 Superflo Pump. The pump is losing it's prime on lower rpm's. The installation instructions said that there should be 5 x suction pipe diameter in front of the pump. I have 1.5 inch piping. That would make the distant 7.5 inches. My length is 3 inches. Do you think this is why the pump is not functioning properly.

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    Richard320's Avatar
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    Re: Pump Losing Prime

    Does it actually lose prime and stop pumping, or do you just see air in the pump strainer basket?

    A lot of people have reported air in the basket on low speed. As long as there's still water flowing, it's normal and nothing to panic about.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Re: Pump Losing Prime

    The water is barely flowing into the basket. The basket doesn't fill. There is air in the system at the high speed start, so I bled the filter at startup. I am concerned that I don't have enough straight pipe in front of the pump, although the old pump worked fine. Adding additional pipe is going to be a pain.

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    Mod Squad jblizzle's Avatar
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    Re: Pump Losing Prime

    The straight pipe is not a problem that is an old recommendation based on the old style pumps that does not make any sense with the newer pump designs. Your problem is that you have an air leak somewhere on the suction side. There is an article in pool school about locating suction side leaks.
    Jason, TFP Moderator
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    Re: Pump Losing Prime

    I don't think the length of pipe will be the issue.

    When the pump is running say around 2000 rpm for 10 minutes, is there still air(or shloshing bubbles) in the pump basket?

    When you shut the pump off, does all the water drain from the pump basket?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Pump Losing Prime

    Yes there are sloshing bubbles, but water doesn't drain completely when I turn the pump off. The led on the pump basket is extremely tight. So much so that I had to use a rubber mallet to loosen it. I'll check out Pool School. Thanks for all your help. I'm glad that I don't have to move that pump back.

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    Re: Pump Losing Prime

    The led on the pump basket is extremely tight.
    hand tight only. Sounds like you have a suction side leak. Pool School will help you.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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