Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 5 of 5

Thread: Please help guesstimate my GPM

  1. Back To Top    #1

    Please help guesstimate my GPM

    I am looking to get a new pump as my 14 year old motor may be deteriorating...
    I posted on another thread that I was looking to get a whisperflo full rated 3/4 hp or 1/2 hp. or a dual speed....
    I have only 1 1/2 inch pipes , so gpm are an issue,,,,mas 985 has been very helpful in education me.

    I have now just found the paperwork of my current 14 year old pump...

    It is a Jacuzzi magnum plus with a magnatec Centurion switchless motor...
    It is 1 hp and an SF of 1.2 and is 60hz...

    With this unit and 1 1/2 inch pipes, there are 1 suction line 50 feet from skimmer basket,,,,1 suction dedicated line for an automatic cleaner that I have never used or even opened, 2 return lines of 20-25 feet with eyeball jet caps...
    no waterfalls or spa or extras..

    How many GPM am I putting out with my current magnatec Centurion system..it was installed 1995, so I got good use from it..
    Thanks
    Ken
    14 x 32 x 6 (ave depth) 20K gallons - IG gunite pool. Challenger 1.5 hp pump and cartridge filter.

  2. Back To Top    #2
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    9,918
    Because the SF of your current pump is only 1.2, this pump would actually have less flow rate than a full rated 3/4 HP Whisperflo which has a braking HP of 1.25. So my guess would be about 50 GPM with your current pump. The 3/4 HP Whisperflo will probably get you closer to 58 GPM.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  3. Back To Top    #3
    mas985,
    Thanks
    so would I still be ok with the full rated 3/4 hp whisperflow or go with the full rated 1/2 hp whisperflo.
    If I went with the dual speed , I would have to go with the 1hp which has the 230 v...The 3/4 dual speed has only 115v set up and I currently have 230v with my current system...
    According to Pentair the 1 hp dual speed on hi speed will push 90 GPM at 50 ft of head, so with my 1 1/2 inch pipe this may not be prudent...

    Which single spped whisperflo full rated should I go with the 3/4 hp or the 1/2 hp...
    Thanks
    Ken
    14 x 32 x 6 (ave depth) 20K gallons - IG gunite pool. Challenger 1.5 hp pump and cartridge filter.

  4. Back To Top    #4
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    9,918
    If you can change the electrical to 115v which is not hard to do, your best option is to go with the 3/4 HP 2 speed. You can simply use one line of the 220v with the addition of a neutral line which should be in the electrical box. High speed would be close to what you have now and low speed would save you 35% in energy costs.

    Otherwise, the next best option would be the 1 HP but I would only run that on low speed.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, 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
    Mar 2008
    Location
    Los Angeles, Ca
    Posts
    162
    The neutral line should be white. Hot is normally black, but my 230 hot lines are blue. Ground better be green.

    Randy
    20,000 gal fiberglass pool, Raypak 266k BTU Lo Nox gas heater, Purex 2048 48 sq ft DE filter, 1.5hp pump. iWave wireless remote, Pulsafeeder chlorine pump, Safety cover on most of the time

    seperate spa, with own pump, cartridge filter, Teledyne heater

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •