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solar water heater

Discussion in 'Heating or Cooling of your AP system.' started by UndaToka, Jan 25, 2016.

  1. UndaToka

    UndaToka Member

    Joined:
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    Country:
    Australia
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    NSW
    City:
    Jiggi
    i have an idea that id like some feedback on
    im thinking of making a water heater using a black poly hose and a 12 volt pump connected to a solar panel, so that the pump circulates the water from fishtank back to fishtank, im thinking if the solar panel is angled right so the sun doesnt hit it till say midday then the water in black poly pipe should be warm and warm rest of water in the fishtank, then when the sun gets low and no longer heating water the pump will be off
    i think i will have the pump intake near the top of FT and the return near the bottom so as to circulate the water more
    the question is will it cause the water to stay warmer over all or would it fluctuate too much, last year in Winter my water was getting down to as low as 12C when i looked in the morning but more often was 14-16C
    if i could stop it going below 16C id be happy
    any thoughts ?
     
  2. Robert123

    Robert123 Active Member

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    It will still fluctuate (perhaps even a larger fluctuation) but the low temperature should still be increased. Additional tank insulation with a tank lid if you don't have it should help. A larger mass of water (ie second tank) will reduce the temp swings. I've heard of people using a 2nd tank in a greenhouse with solar heat NOT piped into the main system simply for the purpose of heat. That way the fish don't see an increased high temp due to the heating, but the low is still increased.
     
  3. Terra

    Terra Active Member

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    south australia
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    Riverland
    It will help a lot I did this on my first systems (different location) the fluctuations are easy to manage .
    Turn it off if needed if your systems temperature is crashing overnight don't heat it up a lot just enough to raise your morning minimum temp a bit .
    If you get overcast or cold wind they lose their effect so I had to watch the forecast and plan ahead (do less sooner)
    Once i get my system here moved to permanent location I will set another one up here it will be handy in the summer as well I will run it at night to help with shedding heat
    Insulation will help a lot , i think most heat is gained / lost through the growbeds .
    So on the extreme days I will run my GBs at night constant flood and siphon through the day , reverse this on the extreme heat weather events .
    If you don't draw extreme cold air into your media the temperature exchange is slowed dramatically.
     
  4. UndaToka

    UndaToka Member

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    Terra i plan to have it automated ie when the sun doesnt shine on solar panel then the heater pump doesnt run
    that way it wont work at night and circulate cold water
     
  5. Moorie

    Moorie New Member

    Joined:
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    Country:
    Australia
    State:
    Cairns
    City:
    Cairns
    Hi guys, I was interested to read your posts......I've just built and connected a solar hot water panel to my system.

    I knew it was going to get cold in Cairns at night over the winter.....so I've been looking at ways of keeping the water just a little bit warm over the next few months. Electric and gas systems seemed a little bit too expensive and not cheap to run so I started looking at "thermal syphon" hot water set ups and decided this would be the best way to go. These systems are usually set up as domestic roof top hot water supplies.....see YouTube

    I didn't see why I could apply the same principal to aquaponics......

    I used some scrap sheets of custom orb, painted black and 20 or so lengths of 19mm poly pipe to make the panel all just pushed together with barbed Ts and elbows. The supply is out of the bottom of my sump and the return is back into the top. To get the thermal syphon effect the panel has to be below the level of the tanks, the principle is that as the water heats in the panel it rises and creates a syphon back into the hot water tank. I could do the levels, but it seems the distance is just a bit too far to initiate a syphon back up to the sump, so I'm using an old 12 volt pump and a car battery to circulate the water. The plan is to hook up a small solar panel for power in the future, but to just test the system and tweak it, the battery is working well.
    I've been running the water heater for a couple of days now....just 3 or 4 hours in the midday sun and in two days my fish tank water temp has come up from 22.5 degrees to 26 degrees. I've got the sump and fishtank insulated, clad and covered so the water temp isn't fluctuating too much.

    I'm really pleased with the results, but I'm sure if someone was a bit more thorough in the panel build and included some insulation and perspex sheeting it would be a lot more efficient.

    I put 40 barra fingerlings in my fish tank 7 weeks ago and the fish and gardens are thriving. (I've included a couple of snaps)

    Really enjoying this little project

    Cheers and best regards

    Moorie
     

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  6. Gratilla

    Gratilla Member

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    IMO the above encapsulates what's necessary for a simple but effective solar heat collector system. If:-

    1) The sump/reservoir/pond is ABOVE the collector pipes, and
    2) The input pipe into the reservoir is ABOVE the output (preferably spaced widely apart), then:-

    a thermal convection current will be set up that makes an inline pump unnecessary! If this design is impossible (ie your collector pipes are on a roof and reservoir at, or below, ground level, then a pump WILL be necessary.

    Also, to handle switching circulation on and off perhaps some kind of thermostat (bi-metallic strips etc ???) could be included. I haven't tried thermostat control, but include it FWIW.
     
  7. Moorie

    Moorie New Member

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    Hi Gratilla.....thanks for the feedback.
    I have the layout as you describe with the solar panel below the level of the sump....but just can't get the syphon to initiate (I even tried priming it by squirting the hose down the inlet out of the sump). Do you think the solar panel could be too far away from the sump? It's about 9 meters. I've insulated the hot water return line with that foam tubing and it is buried. I'd love to do away with the pump, even just for my own satisfaction. Any advice or direction would be greatly appreciated.
    Cheers and best regards
    Moorie
     
  8. Gratilla

    Gratilla Member

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    406
    Dunno. An air gap in your pipe(s) would create a problem; as would an undulating pipe, as this would create a hot spot interfering with the simple convection flow. Checking the temp of the water (with a thermometer) at different spots might indicate where the problem lies.

    PS I don't quite get your use of the word "syphon". Is there a syphon (bell or similar) in the (solar) water circuit?
     

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