A type of air conditioning system that discharges air into the conditioned space via a top-mounted discharge plenum or through an overhead duct system.

Air enters at the bottom of the unit and is discharged vertically out the top.

When an air handler or furnace is installed in an upright position and circulates air through the side or bottom and out through the top. Typically used in basement, closet and attic installations.

a term used to describe the bottom to top airflow through a furnace

A type of furnace that draws cool air from the bottom and blows the warm air out the top into the ductwork. Designed for basement or closet installations.

A term used to describe the direction of airflow through a furnace. An upflow furnace takes return air from the bottom, heats it, and then delivers the warm air from the top.

A type of furnace that draws cool air from the bottom and blows the warmed air out the top into the duct work. This type of furnace is usually installed in a basement or an out-of-the-way closet.