Blog ·
The compost thermometers moved: two in the pile, one in the raised bed
We moved the three compost thermometers this evening. Two are now in the compost pile and one is in the raised bed, which is composting too.
Where each thermometer is now
- Thermometer 1 (the Wi-Fi board, one reading a minute) is in the raised bed, which is composting.
- Thermometer 2 (a small Nordic battery board, every 5 minutes over Bluetooth) is in the compost pile.
- Thermometer 3 (the other Nordic board) has come out of the reservoir water and is in the compost pile too.
The final move happened at about 5:55 PM on October 24. From October 20 until that morning, thermometer 1 sat deep in the pile, thermometer 2 near the top, and thermometer 3 in the water of the reservoir bin that feeds the coil buried in the pile. Thermometers 1 and 2 came out of the pile at about 8:10 AM, and their readings fell toward the air temperature until they went into their new spots.
The reservoir heater is off for now
The bin beside the pile has an electric heater with a thermostat that keeps the water between 127°F and 130°F. That thermostat reads thermometer 3. With thermometer 3 in the compost instead of the water, the thermostat would be reading the pile rather than the water, so we've switched the heater off. It stays off until a thermometer is back in the water.
Earlier in the day the heater ran from 5:30 AM. It warmed the water from about 83°F to just over 100°F, and once the water got warmer than the compost (around 6:30 AM) the pile stopped cooling. The heater's smart plug dropped offline at about 8:30 AM, and the water slowly cooled to about 84°F by the evening.
What the readings mean now
- Two numbers from the pile show how much the temperature changes from one spot to another. On the first evening, the two spots read about 95°F and 89°F.
- The raised bed reads lower, about 69°F that evening. A bed is shallower than a pile and loses heat to the air faster.
- On the charts, thermometer 1's readings from the evening of October 24 on have their own raised-bed chart instead of the compost pile chart. Thermometer 3's water readings from October 20 to 24 stay in the reservoir chart.
- The hours when thermometers 1 and 2 were out of the pile, and the first minutes after each move while the probes settled, are left out of the charts: those readings weren't compost.