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Thread: Help setting pump speed

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    Help setting pump speed

    I have a new to me IG plaster pool 13,000 gallons. I have 6 10x4 solar panels on the SW facing roof in the San Diego area. Pipes for the solar are 2.5". Pump is 1' above the pool and the solar panels are 16' above the pump. I just had an Intellifo VS pump installed, replacing a single speed pump. There are 2 drains on the bottom, one skimmer, 3 outlets, and a waterfall.

    Prior to replacing the pump, the solar alone kept the pool around 85 on average. After installation, the pool is now at 74. Average temperature at my house has been mid 80s. Solar noon is 12:37.

    The installer set the pump at 1600 rpm from 9-5 because that was needed to keep the vacuum running, and 2200 rpm from 5-8. At the low speed I cannot discern any temperature gain between the pool and the water entering the pool at any time of day. The solar controller says it's heating and the valve is in the correct position.

    After a lot of reading, I understand that higher flow rates provide more efficient solar heating. Using the pump chart and .05 gpm/sqft for the solar panels, 240 gpm/sqft I set the pump to run at 1900 rpm from 9-1, then at 2250 rpm from 1-4 when the sun most directly hits the panels, and back to 1900 from 4-7. I think this should turn the pool once in 24 hrs.

    This is the first day it will run fully on this schedule.

    Does this seem like a good schedule to try to get the pool back up to mid 80s (or higher)?

    Thank you!

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    Mod Squad jblizzle's Avatar
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    Re: Help setting pump speed

    Welcome to TFP!!!

    Turn over is meaningless. Read this and ask questions if you still have them: Determine Pump Run Time
    I don't think you should need to run the pump nearly that long.

    I think your estimate of required flow rate is a bit off. I though most panels were looking for closer to 0.1 GPM per sqft of panel.
    Jason, TFP Moderator
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    Re: Help setting pump speed

    Yeah, I wrote that wrong. I will definitely scale back the run time.

    So at .1 gpm/sqft that would be 24 gpm. How do I determine the rpms to get 24 gpm?

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    mas985's Avatar
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    Re: Help setting pump speed

    1900 RPM may not be fast enough to generate enough pressure to keep the VRV closed. Normally, for a two story install, you will need at least 8-10 PSI at the filter. Do you know where the VRV is installed, before or after the panels?

    Also, you need at least 40-45 GPM for priming so when the panels turn on, does the pump ramp up to prime the panels?
    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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    Re: Help setting pump speed

    I don't know where the vrv is installed. The pump does prime.

    At 1900 I have 10psi.

    Just feeling the water at different rpms it feels the warmest at 2000 (12psi). Going from 2200 to 2000 made a noticeable difference in temperature. I think at the higher speed it doesn't have enough time to heat. At 1800 the water gets noticeably cooler.

    So I'm thinking 2000 is the sweet spot for solar efficiency. Sounds like if I run at that speed from 12-5 when it's hottest, I will have enough circulation and heat the water the most.

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    Mod Squad jblizzle's Avatar
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    Re: Help setting pump speed

    That is a common misconception. Solar heating works better at higher flow rates. You will add more heat to your pool by raising a lot of water by a couple degrees than less water by more degrees.

    The solar panels should only raise the temp of the water by ~2 degrees. If you can feel the panels and they are warm, then you are not running enough water through them. The panels should be cool to the touch.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
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  7. Back To Top    #7

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    Re: Help setting pump speed

    Yeah, I read about flow rates before I posted. It would seem that at some point the water would flow too fast to heat efficiently. My understanding is that low flow rates result in loss of heat to the environment. I'm going to give it a few days and see what the temp does.

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    Mod Squad jblizzle's Avatar
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    Re: Help setting pump speed

    Faster (higher flow rate) will never hurt, but there is a diminishing rate of improvement as far as amount of heat added to the pool.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

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