He used off-the-shelf smart switches and some cheap temp and humidity sensors. Not much there to patent.
I’ve got that same Z-Wave stuff running in my house for much the same purpose. Except I’m not drying grain — I’m dehumidifying the bathrooms.
It’s able to be patented in a limited way on the use. Still very important teachings when the alternative costs $80k. I happen to know about these things. I have a couple of patents that people said that the “technology” is already there. The patent would be on a use that the industry wasn’t using prior to his “invention”.