Configuration is the direction the conditioned air will pass through the unit.
Upflow units will have the air come in from the bottom and blow out the top.
Horizontal units will have the air go through the unit left to right, or right to left.
Downflow units will have the air come in from the top of the unit, and blow out the bottom.
Unsure of what configuration your home needs? Call us at 800-865-5931. Monday through Friday, 8:30am to 5:00pm CST