-A type of furnace that takes cool air from the top and blows warm air to the bottom-common where your furnace must be located in a second-floor closet or utility area
A term designating the direction (down) in which water or a regenerant flows through an ion exchanger or filter during any phase of the operating cycle
Refers to a type of air conditioning system that discharges air downward, directly beneath a raised floor, commonly found in computer rooms and modern office spaces