I have thought about zoning my AC for a while, to better balance the upstairs and downstairs, particularly in the summer. I recently found out my neighbor had it done, and is happy with it, which renewed my interest in getting it done or doing it myself. I have a 3-5 degree difference upstairs compared to downstairs.
In researching it further, I see that there are concerns about the decreased flow across the coils and possible higher pressure. Some say to put in a bypass damper, other say that just causes more problems.
So it occurred to me that I could do a partial damping. Perhaps half of the downstairs ducts and half of the upstairs ducts, focusing on rooms that have multiple feeds. This would mean that if only one zone is on, I'd have about 3/4 of the normal flow, with the zone currently on plus 1/2 of the other zone that is does not have dampers.
It would seem like this would give me a better temperature balance, without reducing the airflow so much.
Am I missing something wrong with this approach? Would having half of each floor unzoned eliminate any benefit?