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Thread: Pump Size?

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    Join Date
    Jun 2011
    Location
    Mississippi
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    35

    Pump Size?

    I am looking for help in choosing a replacement pump. My old pump is a Hayward 1HP pump (single speed). It has an AO Smith motor Model C48L2N134D2, Serial Number 30508FM, RMP 3450, Amp 18 6/9.3. My pool is 45,000 gallons with an average of 37 1/2 feet of head. My filter is a Hayward 300 pound sand filter Model S244T with a filtration rate of 20 GPM. According to turnover rates, it seems that my filter is under sized. However, I have always ran my pump 24/7 and it has worked well in the past. Sometimes it takes a little longer to clear up dirty water than what I would like, but that is probably just me being impatient. So my questions are: Should I just replace my pump with a two speed 1 HP pump? What other specs should I look at? If I switch to a two-speed pump, do I need to go up in size? Can I even go up in size with my filter? Thanks.

    - - - Updated - - -

    I may have been looking at the wrong numbers on the filter. The filtration rate is 20 GPM, but the filtration and backwash design flowrate is listed as 62 GPM.
    45,000 gallon IG old (1960s??) painted concrete pool; rectangular 20' by 40' with 12' deep end; one skimmer in deep, two returns in shallow
    1 HP Hayward pump; Hayward Pro Series 300 lb sand filter Model S244T
    Aquabot T4 ("Rosie")
    TF100 Test Kit

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    mas985's Avatar
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    May 2007
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    Pleasanton, CA
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    11,487

    Re: Pump Size?

    If the pump (wet end) is in good condition, I would just replace the motor with a two speed. No plumbing changes required and usually cheaper than replacing the entire pump.

    But what is the pump model#?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Join Date
    Jun 2011
    Location
    Mississippi
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    35

    Re: Pump Size?

    I cannot find a model number on the pump itself anywhere. The pump is quite old so I wanted to go ahead and replace the entire unit.
    45,000 gallon IG old (1960s??) painted concrete pool; rectangular 20' by 40' with 12' deep end; one skimmer in deep, two returns in shallow
    1 HP Hayward pump; Hayward Pro Series 300 lb sand filter Model S244T
    Aquabot T4 ("Rosie")
    TF100 Test Kit

  4. Back To Top    #4
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,487

    Re: Pump Size?

    Ok then the MaxFlo SP2307X102 would be a good choice. BTW, how did you get to 37.5 feet of head? Did you measure that?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  5. Back To Top    #5

    Join Date
    Jun 2011
    Location
    Mississippi
    Posts
    35

    Re: Pump Size?

    Thanks! My main drain line is approximately 45' and my skimmer is approximately 30', so I averaged the two.
    45,000 gallon IG old (1960s??) painted concrete pool; rectangular 20' by 40' with 12' deep end; one skimmer in deep, two returns in shallow
    1 HP Hayward pump; Hayward Pro Series 300 lb sand filter Model S244T
    Aquabot T4 ("Rosie")
    TF100 Test Kit

  6. Back To Top    #6
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,487

    Re: Pump Size?

    Head loss in pipe is proportional to pipe length but it is not equal to it. It is a far more complicated calculation than that and it also depends on the types of fittings, valves, filters, heaters, etc.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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