I live in Kentucky. I want to save money on my heating and AC (use AC only some in summer, prefer open windows). My two furnaces and AC units are 18 years old. Furnaces are 8 seer Heil Quaker. Would like to add a good quality inexpensive heat pump to down stairs area to supplement furnace. My house is 2100 square feet, 1200 of it downstairs. Downstairs heat runs more then upstairs. Current furnaces work fine, no problems. What do you suggest?