Proper Aeration is Key to Grain Storage
To keep grain in good condition, it’s imperative that grain is kept cool and dry throughout the summer.
Galvanized bin roofs can absorb large amounts of solar energy during the summer, heating the air above the grain. Convection currents in the grain flow up along the bin wall and down into the grain near the top middle portion of the bin, drawing this heated air into the grain. Ventilating the space between the grain and the bin roof can reduce the amount that the grain is warmed.
If the bin has openings near the eave and peak, natural ventilation can cool this space. The heated air will rise and exit near the peak, drawing in cooler air near the eave. Note that this will only work if the bin has adequate openings at the eave and peak. If the bin has openings to allow air into the area above the grain, roof exhaust fans can also be used to draw the heated air out of the bin.
Aeration fans should be used every three weeks to cool the grain near the top of the bin and reduce the potential for insect infestations. Using positive pressure aeration to push air up through the grain allows the cool grain at the bottom of the bin to cool the air, which then cools the grain toward the top.
Only run the fan long enough to cool the grain near the top. That may require running the fan for a few hours during a cool, dry morning for a couple of days. Running the fan more than necessary can warm grain at the bottom of the bin, increasing the potential for storage issues.
If the air dew point is warmer than the grain temperature of if the air relative humidity is high, some moisture will condense onto the grain while the fan is running. Condensing moisture will release heat that will warm the air, reducing the effectiveness of the aeration and increasing the amount of warming that occurs at the bottom of the bin. Therefore, select mornings to run the aeration fans when the air is cool and dry.