[RKDinOKC]

I tried.

My vents are all run under the slab and are under each window and next to egress doors. There are two returns in the ceiling at either end of the house. That's where the filters are.

The room my brother was in is the only room on the West side of the house that receives afternoon and evening sun. Despite what you would think it was't warmer in summer and cooler in winter. It was 5 degrees warmer year round, summer or winter. After I put in the small window AC it ran on it's own thermostat and cycled in winter as well as summer. My brother called me in once when there was snow on the ground outside and pointed out the window unit was running. I pointed at a thermometer in his room indicating 70.