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Thread: Solar Heating Results

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    Solar Heating Results

    Hey -

    So I just finished installing my solar heating this weekend, and of course only squeaked out a couple of days of sun before the rain!

    Here's the layout, it was about 8AM when I took this picture. My panels face East.


    Here's a picture of the pool:



    Here's a picture of the start temp & time.



    Here's a picture of the last temp taken around 1 or so. After that it started to be cloudy



    So I got 9 degrees in about 4 hours or so. I wasn't expecting that much of an increase, so my question is, does that sound right, or is perhaps the sensor on my salt system a little whacky? I can't wait till it's consistently sunny!

    Thanks!
    Brad
    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

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    JasonLion's Avatar
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    Re: Solar Heating Results

    That is quite plausible. You gain a fair bit of heat during the day, and then lose a fair bit at night, so if you are only looking at daytime numbers it can be deceptively high.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  3. Back To Top    #3

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    Re: Solar Heating Results

    Ok cool. Ya the first night I lost everything (I forgot to change my programing from night to day) and ran the pump for 8 hours through the solar panels!

    The next day, I started off at 63 and got up to 71 before mother nature attacked. So I lost a 3-5 degrees overnight but picked up 8 during the day.

    Now it's cloudy and raining, so not much going on.
    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

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    mas985's Avatar
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    Re: Solar Heating Results

    What is the size of the pool (surface area and volume) and the surface area of the panels? (no-sig, hint hint)

    6-8 degrees is normal for my system and I can get up to 10 degrees on certain days. But when I use a cover, I only need 3-4 degrees rise.
    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: Solar Heating Results

    That looks like a SWG cover plate on the solar Aqua Solar controller
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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  6. Back To Top    #6

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    Re: Solar Heating Results

    Hey -

    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

    It's not a solar control, wish

    The only thing I'm not sure of is I ran 1/2" OD Poly up to the roof and then it's 1.5" solar headers. Doesn't seem to be much of an issue, I was thinking of switching the Poly to PVC, but don't see much of a problem. Perhaps extra work for the pump/filter?

    Thanks,
    Brad
    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

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    Re: Solar Heating Results

    The poly pipe isn't a problem but the diameter could be. Usually would recommend running 1 1/5" line to and from the solar system.

    skeeter
    47 yr old(1977) 18,000gal Kidney shaped 38ft long plaster Pool with built-in Spa, Pentair Intelliflo VS3050 Pump, Pentair 48sf DE filter, Raypack RP2100 gas heater. HTH 5-way test kit

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    Re: Solar Heating Results

    Ya sorry, wasn't talking about the type of tube, moreso the size.

    Is this limiting the effectiveness of the solar or just putting extra load/pressure on the system or both ?
    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

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    mas985's Avatar
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    Re: Solar Heating Results

    Exactly how are you measuring the water temperature?

    If you are using the SWG, they are usually plumbed after the panels so the water temperature it is displaying is post panel and because of the small pipe, the flow through the panels will probably be slow and the temperature rise through the panels (input to output) will be very high and it won't give an accurate reading for the pool. Also, that is very inefficient installation and you are probably losing a lot of the heat back to the environment.

    Also, do you have a temperature gauge before the panel input or a thermometer in the pool?
    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: Solar Heating Results

    Hey -

    The SWG cell is mounted on the return jet, which is I'm guessing how the the temperature is getting read. So it's getting the temp after it comes out of the panels. Of course, with the panel's turned off (diverted) it's coming right out of the pool. I do not have any thermometer's prior to the panels and I haven't put my pool thermometer in yet (waiting on my stairs).

    You state that this is very inefficient but do not state why?
    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

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    Re: Solar Heating Results

    It is inefficient because the small pipe causes lower flow rates (higher pump head loss = lower flow rates). The lower flow rate through the panels causes a higher temperature rise in the panels. Heat loss is proportional to temperature differences so a higher heat rise in the panels = more heat loss and the longer it will take to heat the water in the pool.

    Also, since the SWG is post panel, during the heat of the day, measure the water temperature with the panels on vs off. Ideally, that temperature difference should be less than 5 degrees to maintain optimal efficiency. The lower the temperature difference, the more efficient the panels will be.

    BTW, are you redirecting all the water through 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

  12. Back To Top    #12

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    Re: Solar Heating Results

    OK that's what I thought about the smaller pipes. I had them already there so I figured I'd try it like that before switching them out for PVC all the way (plus there's been a run on PVC in the city so it's hard to get right now).

    When it's sunny I'm redirecting all the water to the panels. When it's not sunny I'm directing the majority of the water away from the panels.
    15x30 SWG AGP, 1HP Pump
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    Re: Solar Heating Results

    Ok, just a couple of observations, it looks like you probably have room for 1 or 2 more panels on the roof, secondly I agree you are likely not getting enough flow through the 1/2 inch pipe, with your small panel array you would probably be ok with 3/4 inch and almost certainly be ok with 1 inch, if you allowed some of the water to bypass the panels (the flow capacity of 3/4 inch pipe is about twice the capacity of 1/2 inch, and 1 inch is about twice the capacity of 3/4 inch, etc.). With optimal panel flow you should barely be able to tell the return water as warmer than the pool water.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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  14. Back To Top    #14

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    Re: Solar Heating Results

    Ya, there's room for one more panel, just barely.

    Just curious, why would I want some water to bypass the panels?

    Is it a good thing tha tthe return water would have a temperature delta that's barely noticable?
    15x30 SWG AGP, 1HP Pump
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  15. Back To Top    #15
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    Re: Solar Heating Results

    Too much water flow through the panels could overpressurize them causing premature failure, solar panels should be operated at minimal pressure that allows enough flow for heat transfer.


    see this link
    html://h2otsun.com/vahe.html?
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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  16. Back To Top    #16
    Mod Squad jblizzle's Avatar
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    Re: Solar Heating Results

    Right now you are likely not getting enough water through the panels due to the 1" pipe restriction. Once you replace that with 1.5"+ pipe you may not need 100% of the flow through the panels which would pressurize the panels as Isaac stated. You just need enough flow such that the panels feel cool to the touch.
    Jason, TFP Moderator
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  17. Back To Top    #17

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    Re: Solar Heating Results

    OK yes, I remember reading that...thanks!

    And your comment about the temp change being barely noticeable? Is that a good thing, or because I don't have lots of panel?
    15x30 SWG AGP, 1HP Pump
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  18. Back To Top    #18
    Mod Squad jblizzle's Avatar
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    Re: Solar Heating Results

    Yes, solar heating is more efficient with higher flow rates which means a smaller temp delta on more water. You want high flow rates, but not enough to be over pressurizing the panels.

    You get more heat in the pool by adding a little heat to a lot of water through the panels than a lot of heat to very little water.
    Jason, TFP Moderator
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  19. Back To Top    #19

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    Re: Solar Heating Results

    OK thanks. Once the "PVC market" cools down I'll loko at replacing the supply/return lines.
    15x30 SWG AGP, 1HP Pump
    8x20 Solar Heating

  20. Back To Top    #20

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    Re: Solar Heating Results

    Just re-read this. One person said 3/4 to 1" supply/return lines, another person said 1.5" supply/return lines.

    Do I split the difference and pick 1 1/4?
    15x30 SWG AGP, 1HP Pump
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