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Thread: The more I read...the more I get....

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    The more I read...the more I get....

    ..confused!

    Background
    roughly 20 year old, 12K gal, in ground.
    Hayward cart filter 120 sq.ft.
    Dead pump is a Hayward 1 1/2HP motor, yes, way oversized! ( pool orginally had an attached spa....no longer operational, thanks to orginal owners stupidity...same owner that stopped up bother drains.

    So, that leaves me with a single 1.5" pvc to feed the pump, with 2 1.5" returns.

    From what I can determine is my piping will handle a maximum flow of 42 GPM. Determining the head is where I am getting confused. From skimmer to pump is approximately 15 ft, with 4 90 elbows and 2 45 elbows. In reading a few websites is seems 50 ft of head is average. Should I use that figure?
    With the 1 1/2 hp pump my gauge(clean filter) was roughly 11psi....was that about 30 ft of head? (11*2.31+5)

    Any suggestions for a complete replacement pump?

    Thanks in Advance
    Happy Thanksgiving!

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    Join Date
    Jul 2009
    Location
    Monterrey, MX
    Posts
    37

    Re: The more I read...the more I get....

    If you have an equivalent leng of pipe of 50 ft in tha suction side of the pump and a flow of 42 gpm, with 1-1/2" pipe then the head loss in the suction side is 4.6 ft.

    You add the equivalent leng of pipe of each elbow and the pipe, then find in table for 1-1/2" pipe (wich shows head loss for each 100 ft of pipe lenght) the head loss for a given flow and calculate for the lenght you have. In your case is 9.2 ft head loss/100 ft pipe for 42 gpm.

    Then you add the output head loss.

    Gumaro
    10' x 20' x 52" In Ground Pool 6,600 gallons, 2" piping, TFTestkit
    24" Sand filter / Espa Silen 0.8 hp pump

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    Apr 2007
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    Re: The more I read...the more I get....

    fsully,

    I can tell you from several years on these forums that a .75HP pump will do fine. Others are much better at the math if you need to be more precise but I think your answer will still come up 3/4HP.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: The more I read...the more I get....

    Would there be any problems using a 2-speed 1 HP? I found a Hayward SP2607x102S with the switch, that will be a close match to my current set up. Also found a Pentair 340042 Superflo that would work also. Any pros/cons with either of these pumps?

    Any why doesn't Hayward list any electrical specs? Almost every unit I looked at I could find an AMP rating, except Hayward products. But then again I couldn't find dimension on the Pentair products.

  5. Back To Top    #5

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    Sebring, Florida
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    Re: The more I read...the more I get....

    Would there be any problems using a 2-speed 1 HP?
    That makes great sense to me. Probably run it on low 12+hours a day or so and then use the hi-speed for vacuuming, etc. You'll save a lot of money on your electric bill.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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