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Evacuated Tube heater?

Discussion in 'Heating or Cooling of your AP system.' started by Peter the Greek, Jul 17, 2014.

  1. Peter the Greek

    Peter the Greek Member

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    G'day all,

    The water temp in my system right now is about 9.5-10 degrees....not exactly ideal conditions for the introduction of tender young fingerlings. With that in mind, I have done a heap of reading about various heating options and evacuated tubs appear to be a good solution. In particular I have found this one from a guy in SA. The tubes are all glass and the heater is 304 Stainless Steel.

    http://www.ebay.com.au/itm/161360877853?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

    What I had thought was just adding a small pump to the sump to run water through this during the day that will just cycle back into the system. I can then just pack up the system in summer.

    Thoughts?

    Cheers,
    Peter
     
  2. Longnt

    Longnt Member

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  3. Peter the Greek

    Peter the Greek Member

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    Interesting, problem being greater pump costs as I'd need to roof mount that as opposed to sticking the tubes in front of the sump
     
  4. yoodles

    yoodles VIP Supporter

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    do the exac tube work better when you have colder outside temp, id think that the pool one would drop hard in temp if it was in contact with the roof and it was cold,
    im sort of tempted to give that a crack as im in SA not much postage.

    id just run it on a solar pump - it wont work when its dark and colder, and will only fire up with enough sun to run the pump, that and maybe a termal cutout to stop it if its too hot.
     
  5. Peter the Greek

    Peter the Greek Member

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    Yep, that's what I was thinking. What would a solar pump set me back?
     
  6. Longnt

    Longnt Member

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    You don't have to install on the roof. I just throw my on the lawn. The temperature between FT and out side didn't justify the expensive of vacuum tube. That is why the technique mostly apply to hot water. For that cost, I think it is better to use aquarium heater that can turn on at night only when the fish need it most.

    Base on my calculation, the above heater is cheaper than DIY form of black 13 mm poly pipe and solving the problem of air lock in side the coil which I have to use strong pump to overcome it. That is why I bought it. It work really well. On good sun, the return water is 15 C higher than FT water with a 1000L/h pump.
     
  7. yoodles

    yoodles VIP Supporter

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    my issue is in SA its a cold outside area anyway, so any surface that a solar heater would be sitting on would need to "warm up" first.
    for me to run an aquarium heater for 2000L to get it from 10 degrees to say 15 would take 500 - 600 watts constant.
     
  8. Longnt

    Longnt Member

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    That evacuated tube was stated equivalent to 600W assume it got good sun. In winter the sun is less intensive. The average good sun for electrical solar panel is 5 hr/day (whole year not only winter). Most of the heat will be lost overnight where the aquarium heater is better use.
     
  9. Danscraft

    Danscraft VIP Supporter

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    I like the idea but I'd only be willing to try a cheaper version. There are thinner cheaper versions on ebay. only because my parents have a fairly expensive
    5 star energy rating set up on their roof to pre heat house hot water and have found that it really doesn't do much for them through the colder months when you need it the most. Works well in summer but for AP you just don't need it then.
    I've thought of running a long coiled black hose over my roof, then it would take a fairly hefty pump and power to circulate it anyway.
    I decided to settle for the broadest temperature range fish..
     
  10. yoodles

    yoodles VIP Supporter

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    if use an aquarium heater then the cost of running makes it not worth even having fish in the system - 500 watts will be needed most of the time for me thru winter - that will cost me well over $1k a year to run
     
  11. Longnt

    Longnt Member

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    Hi yoodles,
    The solar you quoted only supply average 3KW or 1$/day and due to heat lost through the day, it would be better to run a 500W heater 3 hours at the coolest time at night. You won't achieve much heat with that small heater. The plastic solar heater captures 6 times more sun than evacuated tubes. I have 3 sqm black pipes coil from last winter but this winter is colder so I bought it as it is cheaper than DIY. You don't have to run the heater 24h/d, 365 d/y to cost you $1K.
     
  12. yoodles

    yoodles VIP Supporter

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  13. Murray

    Murray Site Admin Staff Member

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    I have been running electric heaters this winter. Very convenient and easy to do but I shudder to think what my next power bill will be. Days are starting to warm and the night ime temps are higher so have reduced the time heaters are running. I have some on timers. Water temps in the Jade tanks are 20+ today. I have managed to keep the water temps above 15c even on the very coldest nights so I am pretty happy.
    The Jades have continued to feed moderately well throughout.
    The Silver tanks I have just let run without heating. The main system has 200+ Jades in a 2500 ltr tank and it was down to 10C a few nights back. The Silvers are still feeding but only a little. I am very happy with that.
     
  14. Danscraft

    Danscraft VIP Supporter

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    :cool:

    Just to share, Victoria temps are cold, heh. But the coldest temps fall lower than my 1800lt systems water unheated.
    That is a bonus! Its very steady, 9c lowest 12c highest that I have witnessed.

    On a power consumption note. I have one 300 watt heater in my first small 450lt system (on 60min, off 60min) It holds the temp at 15c and that takes more power than all of my three systems together.

    Solstice behind us I see it as a rising soon then game on. Its already on, got to start seeds.
    Ooh I have some chilli hybrids coming this year.drinkanim:)
     
    Last edited: Jul 22, 2014
  15. Linc

    Linc Member

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    Does anyone have solar panels to power their whole setup or run specific things like heaters and pumps?

    Is it worth it for a large system?
     
  16. Danscraft

    Danscraft VIP Supporter

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    Definitely worth the research. Larger plumbing is a key component I'm thinking. It all comes down to how long things last.
    Like battery banks, solar panels, pumps etc. Most things made these days are more throw away and less serviceable.
     
    Last edited: Jul 22, 2014
  17. yoodles

    yoodles VIP Supporter

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    well ive just been out to turn off my gold fish tanks water supply to test the tank drop difference between it and my trout tank
    this morning the tanks were 6 degrees ...
    tonight it was a barmy 9.1 degrees

    ill hook the solar heater up as soon as it gets here, ill prob fold it over on itself and put it in a case and paint it black.
    the sun has been out the last couple of days but its just been cold.
    im lucky my SP's are still small and can still live inside

    over the rest of winder and into early summer im going to move the fish tanks into my shed and build a new green house with double wall plastic.

    then ill hook up a bunch on sensors on my Crestron system and then ill be able to monitor it from inside as well as program everything to do with it (small advantage of being an automation installer for a day job :) )
     
  18. Robert123

    Robert123 Active Member

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    Linc, I'll make it short. Solar power is 10x the price of grid power by the time you get done with panels, inverters & batteries - AND - you get the additional privilege of replacing your batteries every 10 years on top of that (more often if you don't buy true deep discharge cells).

    Yes, I currently have solar - and probably will again when I move - but it is also grid-tied (so ignore the battery costs). Even with that, you are looking at a 7-15 year time span to pay back your investment.

    Your best use of solar is in direct water heating as some in this thread are attempting/using. Set up your controls to flow the water only when the water temp returning from the collector is above that of the tanks else you will be pumping heat out of your tanks. (Yep - the thermal door swings both ways ;))
     
    Linc likes this.
  19. Longnt

    Longnt Member

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    Here is my system temperature in the last two days. It has about 3500L water volume, 9 sqm grow bed surface so a lot of heat loss overnight.

    temperature.jpg
     
  20. Robert123

    Robert123 Active Member

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    That's some good data. Thanks for sharing. (y)

    Are you using that solar collector you posted?
     

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