The temperatures in the biomeiler pile are measured with thermocouples buried in several locations. Nine of them are found at three heights (1’, 2’, and 3’ above the ground) in the inner core, outer core, and mantle of the pile. The graph in today’s post shows the temperatures measured by thermocouples at 2’ height. These sensors are buried 2’ below the upper surface of the pile. A sheet of Reflectix, a tarp, and some snow lie above the top of the pile.
This month, I began recording the number of minutes the air compressor was used to aerate the pile each day. I would attach the air hose and run the compressor during morning and/or evening chores. The black line on the graph shows that data. Each minute of run time delivers a bit more than 1 cubic foot of air to the pile.
The major trend in the temperatures is the same 2-week cycle seen in the January data. In the first weeks of the month, I was usually aerating twice per day. After the drop in aeration time on 2/5, it looked as if the aeration time was strongly affecting the pile temperatures. However, after another week, or so, it looked like too much aeration might decrease the temperatures. I started aerating only in the morning, with 7-8 minutes as the goal. Another 2-week rise-and-fall cycle began at that point. So, the connection between aeration volume and pile temperatures is still not clear.
There were two days in which the hose from the compressor was choked with ice. On both occasions, the pile temperatures were falling beforehand and continued to fall afterward. To me, this indicates that a one-day change in aeration volume does not significantly influence pile temperatures.
In the coming month, I will continue aerating the pile for 7-8 minutes each morning to see if the 2-week temperature cycle continues.
I think you will have these glitches each year, considering the variables of temperatures, humidity, and so on year to year.