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Thread: Pressure on low speed?

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    Pressure on low speed?

    Have my new 3/4hp whisperflo dual speed up and running. Previous dynamo only gave me about 8 psi on my gauge, WF is giving me 14 on high. However, on low speed it's only reading about 2-3 psi. Is this normal?

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    Mod Squad Bama Rambler's Avatar
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    Re: Pressure on low speed?

    Sounds normal to me. Sounds like the new pump is a good bit more effiecient than the old one was.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    mas985's Avatar
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    Re: Pressure on low speed?

    Low speed PSI is about 1/4 of the high speed so that is probably about right. Plus gauges tend lose some accuracy at low PSI. The increase from the Dynamo is likely due to the 3/4 HP Whisperflo having a higher flow rate than the Dynamo.
    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

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    Re: Pressure on low speed?

    Thanks fellas.

    mas, from memory, it seems like it modeled pretty darn close to what you predicted way back when... nice job

    My pool is old, and it only has a skimmer, a main drain and one return. I have never had an eyeball in my one return, just the 1.5" fitting. If I restrict that down to say, .75", to increase circulation on low speed, any reason not to do so? The gauge doesn't change when I manually restrict the flow...

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    mas985's Avatar
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    Re: Pressure on low speed?

    Restricting the return will increase the exit velocity of the water but will also decrease the overall flow rate of the system. So it might help a bit with circulation at the expense of pump run time. It surprises me that the pressure doesn't increase by a little but it could be that the head loss in the rest of the return side is more significant so it is hard to notice.
    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

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    Re: Pressure on low speed?

    I had expected a change as well but it may be and I'm not seeing it do to what you said above about gauges not being as accurate at low readings.

    I'm currently running the pump 24/7 on low, so I may try it and see. I should be getting a bit over 2 turnovers a day based on calculations, and so far the pool looks great.

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