Backyard Aquaponics
A place to discuss aquaponics

Maybe but the design I posted is relatively easy to keep warm.

Stuart I'll definitely be looking for your type of GH, and thanks for the advice.

I spend a bit of time searching and looking at all the auctions sites so something will come up.

Build it yourself.

Second hand timber, second hand tin for the back and sides, second hand glass in the form of shower screens or sliding doors.

I see if I can get a photo of a friends place down the road.

Stuart that might be the way to go and a lot cheaper, if you can post a photo it would be appreciated.

In the meantime I'll keep running the Google Machine

Thank you

Theres a few threads on compost heating, brian fanner did an experiment here viewtopic.php?f=1&t=9684&hilit=compost%2A there are others too.

I think it has some merrit if set up correctly, like cover to pretect from rain, probably better in a small insulated shed to contain the heat, and large enough. But like all heating ideas, the loss overnight normally outwieghs the gain during the day. To get the best from it you would neeed to shut the system down during the night, combine this with good greenhouse design and the propane heater etc there would be a chance of making a difference I think.

The problem I've always had with compost heating was not that it wouldn't work because it probably would but that it would be so labour intensive. You need some way of getting the excess heat out of the compost and be able to get enough O2 in to keep the pile healthy.

I haven't spent much time thinking about it but if you could find a way to do both with minimal labour there would be a few patents init.

Charlie I remember Brian Fanner's thread and have just had another look at it, what I don't like about compost heating is that you need too keep adding fresh compost to keep the heat up.

Also there's fly problems, the neighbors, upkeep, plus the wife's daily inspections to get passed, it's all too hard.


I'm with Stuart on that one.

Personally I wouldnt bother either but thought it may add some value to the thread.

Here's something to toss around:

http://www1.agric.gov.ab.ca/$department ... agdex10721

https://www.extension.purdue.edu/extmed ... -421-W.pdf

http://io9.com/how-spontaneous-combusti ... -698848769

Great thread.

Charlie. Thanks for the lead on the thread by Brian Fenner. The compost heater I am thinking of will use what was termed a thermosiphon. I intend to use a closed loop with heat exchange either to the air in the gh or into the sump.

When everything is built I will test it all when cycling the system to see what the heat gain is.

I will post the results when I get it happening - one way or another.

Thermosiphon are pretty standard bear. It is the maintenance of the compost that is the issue. Getting the heat out of the pile easy, getting the spent compost out and replacing it without having to dismantle and reassemble your thermosiphon is the hard bit.

Ive just done some experiments trying to heat a small greenhouse in mild conditions.
Bottom line is unless you control heat loss through plastic/glass its going to cost a lot of money using gas or electricity.
Comes down to how many degrees you need to gain vs how many you loose overnight

I was warming water just 5 degrees, and coping OK with gas heat exchanger setup, outside temps Ok during day, like 20 deg C, but dropped significantly overnight, down to 10-15. Using 9kg gas per week
This did work well to warm whole greenhouse.

Then temps dropped just a few Deg and was using 9kg per day.
If the gas ran out, in just 6-10 hrs water and house temps would be back to near ambient. House air temps drop in a few hours

The idea just a little bit of energy input will do the job simply doesnt work. Need big lumps of kw when its needed. Wood heating etc would fit the bill but fairly labour intensive and then not cheap for many.