Backyard Aquaponics
A place to discuss aquaponics

As normal chillers can be expensive, and would be required to run 24/7 to keep AP water cool. This may be a viable alternative. And with the DIY skills on this site I could easily see a homemade version.

http://www.ice-energy.com/technology/ic ... ge-system/

Ice Bear sounds about right, it's huge!

I doubt you will be saving any energy for cooling an AP system with that monster, the first model on the list you need at least an 11.5kVA power supply, which is huge. Run that and watch all the house lights in your street go dim I didn't look up prices, but I would think they are very expensive compared to the cost of an AP system.

Typical large chillers used for AP run at about 1.5kVA max. (2HP)

I did basically what that machine does for free, with a large chest freezer given to us, and accumulating lots of ice over a few weeks before spells of hot weather. I put up to 65kg of ice into my FT on hot days, but that's only enough for a degree or 2 of water cooling.

So basically you did a DIY version of this. It's main benefit comes from cooling off at night. Where power companies charge their lowest rates. And you have the least amount of ambient heat to contend with. I was thinking of say a large rectangular poly tank surrounded by insulated refrigerator panels.

Id recommend a very big system for thermal stability combined with a ground source heat pump that way you can cool in summer and heat in winter run by solar panels.

Be prepared to spend the big bucks though.

All my cooling was done with solar panels Ground source HPs are extremely expensive, I think a 1.5kW chiller with a decent EER/COP is the way to go for me, combined with the large thermal mass (13500 litres of water) and insulation. It takes over 15kWh to change my system water temperature by 1C. The problem with the big chest freezer I use is that it's only a couple of hundred watts of cooling, so it takes a few days to make enough ice for one day's worth of cooling, in my small system, which has about half the capacity.

Essentially a chiller is an air sourced heat pump (which I know you know) the expensive bit of a ground source heat pump is the earth works. If you have the land to do horizontal rather than vertical pipe network then the ground source heat pump is not so expensive.

What would be cool would be a solar absorption chiller that had had all the kinks ironed out.

I had a quote for a GSHP here, $20K + earth works! Way, way beyond what I could afford, and way beyond the cost of a couple of high COP inverter RCACs, which I bought.
Yea, absorption chiller could be a good option if it was available, and at a sensible price, but a chiller run from my PV system is just as good for me- with my marginal cost of electricity being zero.

I have had trout over the last two summers without too many problems.This year I had a dome shelter or hoop shed over the tank and it only got to 24c in the worst heat wave that we had.I now have a cooling system which sprays water on a shade cloth but I didn't need it this year.We have made these covers for pigs for years and they work very well

The tank is on the shaded side of the greenhouse.The pipe going up in front of it sprays the water onto the shade cloth and it works a bit like a Coolgardie safe.This year I put 47 into it in December and when I shifted them into the greenhouse a few weeks ago there was 44.One ended up in the frying pan ,it was 260 grams just a nice size for one person.I will be able to keep taking one when I want it into spring.

Have you measured how much water you use per hour on 40C+ days? I'm thinking of spraying fine water mist on my GBs as it warms up in spring to see how much heat I can remove from my system, before forking out for a chiller.

I was thinking about using a chest freezer as a sump, controlled by a thermostat in the fishtank. Chift pist, 2000 L tank, 2 growbeds, swirl and mbbf. Water changes if I needed to reduce any buildup of nitrates. Chest freezers have been used as tanks before
http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=9917&hilit=chest+freezer&start=30

But, is it possible to roughly calculate what size freezer I would need to keep about 3500 L below 18c during a Sydney summer ? Or too many variables and unknowns ? I suppose the bigger the better, it would run for shorter periods. . . . I guess.

If it is Aluminium walled, you probably should line it, Ammonia is very corrosive on Aluminium, so no doubt some Aluminium would get into your water- not good for the fish.

Whether it has sufficient power is hard to say precisely, lots of variables but comes back to: how much temperature rise are you trying to compensate for on a hot day?

However, you need over 4kWh of cooling to reduce the 3500 litres of water by 1C, plus whatever else that has to be cooled- tank walls, pumps, pipes etc. Typical old chest freezers are only 150W, and lets be very optimistic and say they have a EER of 2 (The DC fridge unit I tested had an EER of just under 1). So you'd need to run it at least 13 hours to reduce your water temperature by 1C, I really dont think it will be enough. On a hot day you might need half a dozen or more of them to stay below 18C if the system is exposed to 40C+ for hours on end.

Hmmmmmm, back to the drawing board. I think they are plastic inside but I was going to line it anyway with pondliner. I was thinking also about the Ice Cream chest freezers you see in service stations, being commercial they may be more efficient. And I guess the salmon and trout would be happy enough if I could keep the temperature below 21c.



What sort of chiller would you consider, if you have to get one ?

I would just build a walk in cooler with a 10,000 btu window ac and a coolbot controller. That should put you under 3 kWh. Lots of people I know on other forums use them for hanging deer. I know they can keep it at 37f when it's mid 80's out. Put the tank inside and make it RAS for the summer.

http://storeitcold.com/howitworks.html