Guidelines to set your fans for long term storage
Responding to your inquiry about fan settings, here below are some general rules:
Fan settings; if the goal is to dry grain down, which should be part of any discussion for long term storage, you should use "natural air drying" (NAD) for your fan on-off automation. This uses moisture as the primary decision to run the fans. Your target for setting should be to set the EMC (equilibrium moisture content) to your end goal target. Look at your average moisture content in the bin and set the plus to be below that. So, if your target is for 15%EMC and your average bin moisture is at 18%, you might put in a plus 2 for 15 plus 2 =17 so any time the ambient moisture is 17% or below the fans would run. On the minus side, you do not want to over-dry the grain but need a lot of run time when the grain is wet so you would set a wide window on the lower side for wet grain and as you dry it down, you tighten the top side to stay below your average grain moisture and the bottom side so as not to over-dry.
For grain that is hot and dry, you follow the same process but set your fan to aeration mode so the system uses grain temp as the primary decision mode. We do not recommend freezing grain but the cooler you can get it the better for long-term storage above freezing. Again, you set your target for the temperature to your end goal. On the plus side, set so you run your fans below the current grain average temp. If your target is 4C and the current grain temp is 30C, your plus might be 22C, so any time the ambient temp is below 26 C the fans run. As you cool the grain, you would tighten that down. On the bottom side, you might use - 3C.
If you are looking at short-term storage you might not want to spend so much on running the fans so you could use tighter targets.
Screenshot from Integris
Screenshot from OPI Blue