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Thread: Solar heater- pump speed question

  1. Back To Top    #1

    Join Date
    May 2009
    Ontario, Canada

    Solar heater- pump speed question

    We installed 4 boxes of Enersol solar panels. Despite the cloudy and sporadically sunny days, with the pool heater, we've hovered around 81 by afternoon each day and hopefully we'll go even higher this week with 3 days in the forecast of actual SUN!!!!

    Anyways, Hubby and I are disagreeing on something.

    I told him that the pump is suppose to be on high to work properly.

    He thinks that with the pump on "low" the water goes slower and the water heats up more.

    I notice that when the pump is on low there are many air bubbles always coming out of the return. None when on high. (and no bubbles in pump basket either way)

    Who is right?
    21' 54" Round AG, 10K gallons,1HP 2 speed pump, Sand filter 200lb
    Have had a sparkling BBB pool all summer....

  2. Back To Top    #2

    In the Industry

    X-PertPool's Avatar
    Join Date
    Jun 2009
    Exeter, PA

    Re: Solar heater- pump speed question

    Leave it on High, the solar will work better not to mention turn over the water more.
    X-Pert Pool Service
    X-Pert Pool on Facebook and @XPertPoolServic on Twitter
    22,000 gal / 16' x 32' / Vinyl / Hayward s244t /Pentair SuperFlo 1 hp

  3. Back To Top    #3
    mas985's Avatar
    Join Date
    May 2007
    Pleasanton, CA

    Re: Solar heater- pump speed question

    Heat transfer is proportional to temperature difference between the incident solar energy and the pool water. So by letting the water heat up on slow speed, you are actually reducing the heat transfer of the panels. So high speed is usually the best option for heat transfer. However, heat transfer will max out at a certain flow rate so increasing beyond that point yields little benefit.

    Also, probably the reason you are seeing air in the returns is because low speed usually does not have enough pressure to keep the vacuum release valve closed (assuming you have one). Are the panels installed on a roof and if so, is it one or two stories? Normally, a two speed pump does not have enough head to keep panels primed on a two story house unless the vacuum release is installed near the pad.
    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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