That's a good design for AC but not very good for heating. Hot air rises so it tends to be hotter from 4 ft up and colder below, especially if the slab is uninsulated.I don't know my HVAC terminology all that well, but it's an A/C + propane furnace system, both operating via forced air through ceiling ducts. I would love to have hot water based radiant heat, but apparently the builder saw otherwise. During really cold weather, this system burns a ridiculous amount of propane (sometimes running nonstop for 24 hours or more) and we never really feel warm. The wood stove has been a tremendous improvement in that regard. We're very happy with it except for the uneven heat distribution, particularly at night.