Why One Temperature Probe Isn't Enough

A single temperature probe pushed into the top of a silo is better than nothing. But it measures one spot, in a material that’s very good at keeping heat where it is. Here’s why that matters.

Grain is an insulator

Stored grain conducts heat poorly. That’s useful — once you’ve cooled grain, it stays cool for a long time. But it also means heat produced in one place doesn’t spread quickly. A hot spot can grow in the middle of a silo while grain half a metre away stays at the same temperature it was last month.

A probe at the top only “sees” the grain right around its tip.

Where problems start

Trouble rarely starts where it’s easy to measure. Common starting points include:

• The core under the fill point, where fines and broken grain collect and airflow is poorest.
• A wet layer from a damp load, a leaking roof or a storm during filling.
• The top surface, where condensation forms as warm grain meets a cold roof.
• Near the walls, where the sun heats one side of the silo.

Each of those is at a different height and position. One probe can’t cover them all.

Layers, not averages

Even without a hot spot, a silo isn’t uniform. Aeration moves a cooling front through the grain, so the bottom cools first and the top last. Grain loaded on different days sits in bands with different moisture and temperature.

With readings at several levels you can see:

• Whether a cooling front has made it right through.
• Which layer is the wettest or warmest.
• Whether one band is trending up while the rest are steady.

That’s the difference between “the silo is 18°C” and “the silo is 14°C except for a band at 4 metres that’s climbed 3°C this fortnight.”

Trends beat spot checks

A reading taken once a month tells you where the grain was that day. Daily readings show the direction of travel. A layer warming by a fraction of a degree a day is invisible in a monthly check and obvious on a chart.

How SiloSense helps

SiloSense IQ uses temperature and humidity cables with sensors at multiple levels down the silo. Every level reports daily over LoRaWAN, and the dashboard shows each layer’s temperature, humidity and calculated moisture, with history charts for spotting trends early. Add a headspace CO₂ sensor and you have an early warning that doesn’t depend on the hot spot being next to a sensor.

Request a demo to see layer-by-layer readings from a live silo.