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PostPosted: Apr 21st, '14, 08:11 
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I would check this thread out first viewtopic.php?f=8&t=3976&p=142855&hilit=evacuated#p142855 :)


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PostPosted: Apr 21st, '14, 08:41 
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I studied that thread but it was inconclusive. Plus the scale of his system is much bigger than my planned 2 IBC system.


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PostPosted: Apr 21st, '14, 10:49 
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Well a definite pat on the back for the design. My biggest thing that jumps out at me is why is this directly over the FT/ST? If you're not gonna bother putting it outside the greenhouse (or if you don't have a greenhouse), then why not just paint one side of the FT black and put a few mirrors/reflectors around it to focus light on it?

Currently my team of 5 Engineering Students and myself are designing (have been for the past year) a setup for our school. This is exactly what we're doing. Just an array of mirrors around the tank, although technically ours are outside the greenhouse reflecting light into the greenhouse, not only heating the FTs, but also allowing us to do higher-density stocking because of the added sunlight.

The other thing that jumps out at me is this: although you are from a very moderate climate, don't expect to add more than a few degrees to your water (depending on how big your solar array is vs your total water capacity). I don't know how big your setup is, but ours is about 2500gal and we're predicted an average increase in temp around 2-3 degrees Celsius through the usage of 3 decent-sized reflecting mirrors. Due to your climate you might get away with only using solar, but personally, I wouldn't risk it if you've got a lot at stake here. Water heaters are not that expensive.


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PostPosted: Apr 21st, '14, 19:17 
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Directly over or in the FT/ST to take advantage of thermal siphoning and eliminate the need for a pump. I certainly can set the array to be extended from the FT/ST, but with space limitations in my yard, it would be more of a challenge. Also, the further the array is extended from the tank, the more space available in the pipes to allow the heat to dissipate. So I figure, why not take advantage of the space available to me immediately above the FT/ST where I will have no grow beds. Water heaters aren't expensive and I know that I only have a short cold period to get through but that short period is very cold. The idea of sustainability appeals to me even if investment costs are higher. I guess it is the tinkerer in me.

Anyways, if I ever get the aquaponics system off the ground, I will be sure to make a detailed post.


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PostPosted: Apr 22nd, '14, 22:16 
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anassri wrote:
6) I may have mentioned this before, but INSULATE. By far the best way to heat your water is to not lose heat in the first place. Double-insulate your greenhouse, insulate the solar array, insulate the piping that goes out of your greenhouse, insulate your cats and your dogs and your kids. If you do it right you'll save a lot in future operating costs.

Help! I insulated my dog, but the water temps keep dropping! :wink:

[On a serious note, good info, Anassri. Thanks.]

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PostPosted: Apr 27th, '14, 19:08 
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Ive just got a good heating system working.
Bit of background, was looking at solar using OKU panels, firstly expensive and with limited capability. Decided to give these a miss but would form part of a complete setup in my mind.
As far as capacity goes electric or gas are only easy options. Finding fish safe electric systems which work efficiently is also difficult, and with max 2200w they will run a lot of the time. $$ per kw wasnt too good.

I have fairly high capacity 12v dc pump, and using instant gas hot water setup is working well
A key problem is the internals of these units are all copper so needs to run as heat exchanger to avoid killing fish
I use just 20 @ bucket as tank/ heat bank, bigger would give more capacity and less starts. A 25 m roll of 13mm LDPE pipe in the sump does a surprisingly good job of transferring heat
Gas HWS works great, bit too fast in fact and has to be throttled back, it takes 20-30 l to 55 deg in just 10 min, then another 15 minutes to pass this onto main AP water
The system needed automation as the HWS has safety cut off at 50 deg C and wont restart itself. Pump is set to run full time moving water through the HWS and back to heat tank. Using a day timer and soon a cycle timer the gas system will reset for another heat cycle as required to maintain up to 26 deg easily, in my case around 17 runs per day does the job. thats maybe 5-6 degrees above normal. Plan to add a thermostat to prevent over heating.
Gas usage is around 9 kg bottle per week, maybe a bit less.

What others have said regarding insulation is true but way easier said than done, have to look at whole environment including any grobeds. Wind seems to be a big impact as well as night temps sees all the added heat lost every night.


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PostPosted: Sep 25th, '17, 14:58 
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Hi Markymark,

I set up a solar heater for one of my systems that has worked quite well this winter. We don't get snow and rarely get a frost, but water temps can get down to about 10C (about 50F) over winter. This is enough to shut down my silver perch, meaning very little nutrients getting to the plants.
I used 100m of 13mm black poly tubing wound around a wire mesh cylinder of about 1m high and 45cm diam, slightly squashed to an oval x-section to increase are facing the sun (north in Australia). I wrapped foil insulation over the mesh and then wound the poly tubing over that, held in place with cable ties. I then took the outer frame of an ibc base, and placed a wire mesh as a concave solar reflector, again with sisilation foil held in place with cable ties and placed about 20cm behind the coil as a parabolic reflector. I expected to gain about 4C above ambient, but on bright days managed to increase water temp up to 5.5C on some days, which kept the fish more active and the whole system ticking over.
Unfortunately, I have not mastered the art of placing photos on forums, so I hope my description is sufficient.


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