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Thread: Please check my filter and pump calculations

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  1. #1
    Join Date
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    Default Re: Please check my filter and pump calculations

    Quote Originally Posted by BuckeyeFanInFL View Post
    There is approximatly 20' between my pool suction and the pump suction, so I will need to check the pump curve at 20' of head.
    First, the parameter of interest is total system head, from the pump discharge all the way back to the pump suction. Your statement only considers "suction head".

    Also, head is more complex than the straight run distance from point A to point B. A turn in the pipe (elbow) adds a significant amount of head relative to a straight piece of pipe of the same length. Also, there are valves, as well as equipment (filter, heater, etc.) which add resistance.

    Calculating total system head is very difficult and imprecise. The consensus on this board is that, after all is said and done, your total system head will be between 45 feet and 65 feet.

    Do the same thing you did before, using the upper and lower ends of that range. That will give you a better idea of what you need.
    Pool owner - contract signed 21Aug2006; HOA approval granted; complete - existing patio demolition; excavation; rebar; embedded plumbing; gunite; plumbing; electrical; tile and coping; decking; plaster; pool fill; acid start-up; regular start-up; pool school; gas meter upgrade; additional of salt; PDA remote programming.

  2. #2
    mas985's Avatar
    mas985 is offline Lifetime Member Whizbang Spinner mas985 3 stars mas985 3 stars mas985 3 stars
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    Default Re: Please check my filter and pump calculations

    It will be very difficult to find a pump that will have a flow rate that low. Even a two speed pump is likely to exceed that at low speed. So my suggestion would be to look at 3/4 HP two speed pumps as these are about the lowest HP and flow rates you can get on the low speed. You will get about 70 GPM @ 50' head on high speed and 35 GPM @ 13' head on low speed. A bit higher than what you want but it won't cost you too much to run either.

    In addition, the Whisperflow 1/2 HP pump has about the same current draw as the 3/4 HP motor. I think it is acutally the same motor and they use a different impeller. So it probably does not pay to go down to the 1/2 HP pump as it will cost the same to run.
    Last edited by mas985; 11-28-2006 at 11:43 AM.
    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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