Backyard Aquaponics
A place to discuss aquaponics

Now that's what I'm talk'in about!

Ian, definitely pimped now. THAT ROCKS

Hi all,
Don't really know whether to start new thread or not? So I'm going to put it here in the first instance, as it will be part of the IBC system.

I once saw a compost heater arrangement that intriqued me and I am going to construct a trial one similar to that for the outdoor IBC system. I think it may have been Francois in RSA, but I can't remember? Anyhow, apologies for "borrowing" your idea.

This Compost heater arrangement is designed to be a top loading, continuous process system rather than a "batch" system which I have seen used for Hot Water for Showering etc. In this case the water will be recirculating continuously from the Fish Tank and not used up as in a Shower or the like. This should mean that a gradual heat build-up will occur, if the water can gain enough heat to overcome the losses in the FT. I have read that the temperature in a controlled compost pile can be up to 90 degrees C (175 degrees F) so I don't think heat gain will be a problem for uPVC piping.

The mainly vertical clear geometry of the tower manifold allows composting material to be "agitated and aerated" towards the base and removed at the base opening. This (incomplete) Compost material can then be finished off in a standard compost pile for later use. All the tower is doing is promoting the initial "heat producing" part of the Composting cycle for use in transfer to the tower manifold for production of a natural Thermo-siphon. A 25mm Radiator Control Valve with a remote sensor in the Fish Tank will allow the thermo-siphon to continue until the temperature in the manifold is less than that in the Fish Tank, at which point it will automatically shut off until the temperature in the Compost tower manifold once again increases to be greater than that in the fish tank.

I have some left over 600mm diameter PVC column forming tube for the liner, strap some 50mm thick foil faced FG blanket with 200mm square Galvanised mesh around the outside and all the fittings are standard 25mm Diameter uPVC pressure fittings: 45 degree elbows and standard Tees.
Anyhow, I'm starting to build it to be plumbed from the valved outlet at the bottom of my IBC tank and feed back into the top under the sliding Grow Bed at the back. Let you know how it performs, if it performs and by how much.

Cheers IanK

Hi Ian, will be very interested to see what temperature differance you will get out of this.Will keep an eye on it

Hey Ian, is the water going to enter from the bottom pipe and come out the top as indicated in the diagram?

Also, just checking if what I think is correct, the 'compost' is just kitchen trash and things that decompose, i.e. trash, which will produce enough heat, almost 90 degrees C as your post says?

Yes, that is the theory; but I think I will need to put a small circulation pump (or the like)to aid the Thermo-siphon flow, especially when the hot water pipe goes "down" at the outlet back to the Fish Tank. This may not work as a pure thermo-siphon. I need to do a bit more research. I'm sure that the hot water outlet must always point upwards to allow the convection to work; no down turns to get temperature locks/inversions.

Compost needs wet and dry materials (no meat etc), be kept moist (but not wet) and be agitated/aerated every now and then. Grass clippings, small mulched tree branches, wood chips, newspaper, dry leaves and other vegetable and fruit scraps (not those to be fed to the chooks); plus some composting worms (as you should have in your Grow Beds) are all required, along with a bit of Lime perhaps, and away it goes!. Composting is a science in itself and needs to be monitored and controlled to be effective. Just Google Composting and all will be revealed. I choose this trial method over say Solar heating, because the composting process doesn't stop at night, when you need the heat most! And yes, trials have measured temperatures of up to 90 degrees C, although I'm not counting on that amount of heat. Will keep you all posted.

Cheers IanK

Will there be enough volume of compost in the trial unit to actually compost and get some heat? I know I've read somewhere in the past that you need a certain volume for the heat to build up with the composting action..

Just mentioning this so that you don't chuck the idea totally if the small version doesn't get much heat. Sometimes bigger is better.

Certainly a nice neat idea.... I'm trying to remember who tried a compost pile to heat their water, I know someone tried with just a compost pile on the ground.

Yeah EB,
The concensus is that if you have a "pile" compost heap, then they say that you require about a 3 foot diameter minimum, at the angle of repose of the composting material (about 45 degrees), to get enough "critical volume" to generate the heat of composting in the centre of the pile. Same as the heat of hydration in concrete: i.e. small pad, little heat (larger surface disappation area for that small volume) but the heat still happens, just that it can dissapate more quickly than a thick slab.
However . . . I'm hoping that by containing a similar total volume of composting material in an insulated cylinder, that lowers the available surface area for heat loss, as well as not allowing direct contact with ambient air, as a ground pile would, I will overcome the critical mass issue. Also, the pile on ground is a "batch" method that does it's work and then needs replacing.
I hoping to have a "continuous" system by filling with suitable material at the top, "heating" (probably Lime assisted) this through the initial stage and then unloading this semi-composted material at the bottom, to be finished off into usefull compost in a normal bin.
The trial will be with a Higher "tower" than the one I have "drawn" for the existing IBC FT access height, but I'm hoping that I will be able to reduce the tower height and keep the thermo-siphon going while still generating some heat for transfer to the FT! All sounds good in theory, we will just have to anticipate as many problems as possible and eliminate them for the sucessfull operation of the protype/trial.
I'm not a quitter . . . just a change of hats every now and then!

Cheers IanK

Should not have posted twice!

Ahhhh so you have done your research first......

I thought AM did it with black poly pipe on the ground and compost above it.....maybe the school system?????

. . Sorry, just got to post this:

I was sitting watching how the new fish were going to-night in the mega-bin system . . . when the Dobbie finally discovered the fish life through the windows.
I reckoned it was priceless! The fish took no notice what-so-ever!!

lol, dobbie looks mesmerized

Perhaps it was... http://onestraw.wordpress.com/2010/05/2 ... omposting/

are they non return valves onthe inlet/outlet?