Something I don't get about some of the entry-mid level commercial coffee roasting machines lately: what's up with using VFD pots instead of a controller that can piggyback on the existing modbus line? It's like someone said, "we have this capability, but you know what? Let's make roasts less repeatable and harder to log."
I do have a fuel control pot on one of my machines (I'd like to swap that out, too) but at least it's a dual-pot and the 2nd circuit is running through the same data acquisition hardware. It's not like there's some weird 2nd system for just one control variable.