Backyard Aquaponics
A place to discuss aquaponics

Here is what I am thinking.

One of these http://www.tumbleweed.com.au/pages/defa ... e_id=19969

With a spiral of black plastic pipe spiraled around inside it against the inside wall. pipe as long and as many winds as possible - looked at B today and I think you could fit atleast 50m of tube in there - if not 100m.

Use a hole saw to make 2 holes in the barel - one for each end of the pipe and fit those quick connect hose fittings with the sealing valves (so the fluid in the heating coil does not run out when it is unclipped.

That way you can simply unclip the hoses and tumble it once every few days, top it up with grass clippings and then clip it back into the system pump ready to keep the fish tank warm.

You could also wrap the compost tumbler in a thermal wrap to keep the heat in.

If there was a 12V pump trickling the water through this pipe then it could be controlled with one of these - only kicking in when the temp in the tank drops below a set level.

They say these are really god for grassclippings and the tumbling really speeds up the decomposition = more heat!

Set up the way I describe would also mean that you dont need to rebuild a pile and muck around turning piles with a fork etc to keep the temp up.

It also makes it really easy to empty - you just tip it on the frame.

Links to thermostats...

http://www.jc-solarhomes.com/MTD/12_vol ... ostat_.htm

http://www.maplin.co.uk/SEODynamicPages ... odNo=31698

http://fadisel.com/Producte.aspx?refere ... -60%C2%BAc

http://www.heatmisershop.co.uk/Programm ... 16141.html

Anyone got any thoughts on these ideas?

Cheers.
Hamish

As with most "pipe dreams " it's just not practacle. The amount of energy supplied by a small compost pile would be lucky to heat 10 litres of water to any extent.
I do use compost to warm my seedling beds and for that it is great.
AHHHHH , I'm assuming you don't have a 300 cubic metre compost bed?

Compost , as well as Solar also is at it's weakest when you need it most ( winter / night).

ground heat is a very usefull source ,, but not many of us live near hot-springs. So , I at this stage I can find nothing better than good old electricity.

Compost does heat up, no doubt about that but it can only really provide low grade heat for most purposes. As in it may be great to give a little extra warmth boost to greenhouse seed beds and such but it is unlikely (at least on a backyard scale) to keep water in a cold climate (by cold climate I'm talking freezing temps and perhaps snow) above 20 C.

I kinda like the idea of piling mulch around grow beds to insulate them and perhaps add a little warmth but the bug angle needs to be taken into account.

I make really hot compost but since I don't believe in the heavy work of turning it every few weeks, I would not be likely to try it for water heating.

Unless someone has access to commercial quantity's of compost, I suspect that solar water heating will be far more effective for the effort and cost. Use an insulated thank and heat exchanger for warming system water at night with the previous day's solar energy. If using a solar pool heater (usually they don't have glass) in summer you could probably reverse the cycles so that you chill the water by running it trough the panel at night and heat exchange with system water through the day.

Nice idea about using a pool system and reversing it in winter. I guess the house hot water heater having glass means its insulated and would not give the heat off to the atmosphere when used as a cooler in summer?

I collected about 50 x 35 gal. bags full of leaves with the intention of building a 6' tall by 9' wide compost water heater. Then my lady and I had our baby. Those 50 bags of leaves are slowly turning into compost on their own now... /le sigh.