My ruminations of adding zone control to an existing A/C system.
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Let the built-in logic of A/C unit make all the decisions about how to control the variable speed capability of your system. It has all the logic necessary to optimize the system functions and at the same time protect the system from operational damage. If you try to manage the internal workings of the system, you may need to start managing some of the safety logic too. This is best left to a dedicated controller designed and configured for your specific A/C system.
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Use an A/C zone controller to handle all the coordination of zone thermostat calls, damper position, and calls to the A/C system.. Honeywell and others make these.
You can certainly use HE to do this if you want to. My personal belief is it is best left to a dedicated controller that is designed for that purpose. Hubitat has it's place in all this. Just not here IMO. -
Here is where HE plays it's part. Use Zigbee or Z-wave thermostats. This gives you connectivity to see the zones, control setpoints, and schedule setpoint changes. Using modes for is a great way to adjust temperature setpoints. I personally Like the Zen thermostats since they do not complicate the thermostat user interface with scheduling functions.
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Be sure you install a properly sized bypass damper. Since you have a variable speed system, you may want to get some help with this, since the system may vary the blower speed too.
