I was just watching the video on using the heat from a compost pile to heat water for a shower, where a length of pipe was laid back and forth amid the compost heap. I've gotta say I'm more than intrigued by this idea, but I wanted to know what sort of pipe was/should be used for this application? Anyone know?
2" rural irrigation pipe would be the best. You would also need to have the pile made using at least 15 cubic metres of chippings if you want to have heat for any length of time. The chippings also need to be re chipped until they are literally wood shavings. I am about to take my chipper to an ironmonger to have him retro fit my chipper so it can lock chips inside until I am happy with the size (like a blender) and them release them. Also the big mistake most people make (usually due to lack of space) having the irrigation pipe too close to the outside of the pile. I would say that the pipe should be 1 metre away from the top, bottom and sides. I am just about to build my own pile so I will post my videos and data.
I made a 18 cubic yard pile using wood chips last fall. We didn't have much time to make it and I only chipped it through once with our tractor pto chipper so the pieces where not nearly small enough for a quick start up. We used made a 4 foot diameter 6 feet high coil of pex and then a 13 foot diameter ring of fence to hold the pile up. I had chipped the wood and shaped it in a birds nest shaped pile in hopes it would absorb water before we put it in to the final pile. We added a little bit of apple pumice since we had just pressed a bunch for cider. One of my chip piles shed more water then it sucked up so we rain the hose while making the new pile. We piled it up and I was made fun of for the next few months because it just sat there.
We got plenty of snow this winter but it never would build on the peak so it was generating a bit of heat. Not a lot but enough to keep from freezing. I put our bird feeder on top of it hoping the birds would do their business on it. On a few warmer days I made a slurry out of some of our chicken and horse manure and poured it onto the pile figuring a nitrogen boost would help get it going. I also buried a chicken that a hawk had gotten to. I also made it my routine place to pee even on the coldest of nights. The pile kept going pretty slowly. The compost thermometer would read around 80-90 degrees in the top center. Not really warm enough to do much for water heating but it was a start. We even had some sunflower starts on the top of the pile in the middle of march. Once they were tall enough though they got whacked by the cold.
We had another chicken attacked and I buried it along side the other. I didn't pay much attention to it because we have so much going on with our other projects. One day I was making my nitrogen deposit and I noticed that it was radiating a good amount of heat. I raced inside to get the compost thermometer and when I stuck it into the center of the pile it was up to 115 or so. The outside ring was still down in the 80's so the heat exchange would still not be excellent but we were getting closer to success.
I hooked up the hose to the pex to see what change the pile would have on the temp. I forgot to check the gallon per minute while I was doing it but it wasn't super high since my hose hook up was make shift and leaking significantly. The water going into the pile was around 55-60 degrees and with a steady stream going through it it would take the water up to 80. Not great but it would be a good preheater for our solarhot water panels. I just checked it yesterday and the inner ring is up to 120 and the water gets to about 90 degrees.
Our plan for this pile is to add more chips and green material getting it to about 25 or 30 cubic yards. We are going to move it down to our mobile greenhouse for the winter and try to have a radiant heat system to keep the high tunnel just above freezing.
Our pile has been at 120 degrees for a month and a half now with lots of material still to break down. I did a makeshift test and found that the at .5 gallons a minute the pile would take our spring water from 60 degrees to 101 degrees F didn't do a btu calculation yet. I ran the water for at least 10 minutes with no drop in temp.
Hi all, I have done some mushroom cultivation and read all of Stametsbooks and realized one could build an insulated room or use an insulated shipping container like they use for pasteurizing the compost for mushroom growing. The difference would be in placing pex tubing in/on the walls and ceiling so you could capture the heat generated but be able to load/unload with a loader without concern about moving/ breaking your tubing. You could even have overhead sprinklers/drippers to add moisture/pee/greywater/blackwater to keep the N/moisture/temps at optimal levels. Similar to phase 2 mushroom bulk strata rooms, you get heat/pasteurization all through the compost without turning.
A few years back I built a very hot compost which was roughly 1 yd.³. I used leaves and plenty of chicken manure to get a hot burn and in the top center under about 1 foot of material I placed a full aluminum beer keg of water. A few days later it was too hot to bathe in. One of these mounted on a permanent stand with 18 inches of ABS for a filling tube and a garden hose outlet would give a reasonable size batch of hot water from a small space and with no long runs of pipe. Of course I did this when there was plenty of sunlight available and in that same period of time a breadbox style soar batch heater would've given me far more hot water .
I have wondered about running a soaker hose next to the heat exchanging hose. Cap the end of the soaker hose. It could be used to pump air and or water into the pile. This would appear to be a useful addition to a pile that you can't easily turn. Thoughts?
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