That is a thing of beauty AmaxB! I hope it works as great as it looks!
I have my first grow germinating and hope to build a kiln for fermenting in the fall (very simple 2" rigid foam inside a wood frame). I am playing around with some Arduino boards to try much of what you have wired here for flue curing but on a much more modest hobbyist scale
(I'm a programmer, so that comes FAR easier than the electronics portion)
I was thinking stepper motors to control automatic venting for humidity but not sure yet until I play around some more whether they will be strong enough to open/close a vent and create enough of a seal when required.
Heat/humidy will be facilitated by the traditional crock pot and turned on/off with a powerswitch tail.
Your project has me chomping at the bit to get out the garage and build it
Thank you very much for documenting your project and sharing along the way.
Cheers.
W.