So quick recap of the situation, I have a Trane XE80 in my attic 3ton cooling unit. Live in a 2 story house 1750 sq foot in GA, so winters can be cold, and summers very hot. 2 returns upstairs and downstairs. The thermostat is in the middle of the stair well between the 2 returns.
My dad was able to tell me that I could adjust the blower speed so I set now heat to high and cool to med-high (reversed what it was). However, he disagreed against doing a zone control. I figured if I created two zones upstairs / downstairs with thermostats it would greatly help the comfort of the house rather than upstairs an inferno while downstairs is cold (at least right now). His point was that really a HVAC "sucks" the air from the registers to the returns. And by zoning it I would greatly hurt my efficiency / air flow.
What are your thoughts? I planned on using HZ311k (3 zoner) and then put in 5 dampers (1 for downstairs, 3 for upstairs, 1 for the master) to have 3 zones. I appreciate your advice or suggestions!