I have a little concern over attempting to implement two controllers to handle the 24 zones that I operate.
It would appear that I would need to incorporate an 8 zone and a 16 zone controller to handle my zones.
Utilizing the two controllers that are not bridged together could create timing issues if any zones in the first controller needed to be modified for their run times. The cascading effect of timing could create issues when adjusting the start time on controller 2. I also see issues with the visual display in that you would need to review both controllers in order to activate zones.
I would like to suggest that consideration be given to 1) creating a system that handles more than 16 zones or 2) developing an interface application that spans/bridges the two controllers into a seamless app. 3) possibly design the base system to allow for expandability by adding modules which cascade from the main unit. The modules could be in increments of 2 zones, 4 zones or 6 zones thus allowing for someone to purchase a 16 zone base unit and the a separate 6 zone unit for a total of 22 zones.