AC Industry Terms

AIR DUCT : A conduit or passageway for conveying air to or from heating, cooling, air conditioning, or ventilation equipment, but not including the plenum

AIR FILTER: A devise used to reduce or remove airborne solids from heating, ventilating, and air conditioning

AIR HANDLER: The indoor blower equipment in a furnace, heat pump, or similar appliance designed for circulating heated or cooled air through a central heating system

COMPRESSOR: Motorized equipment in an air conditioning system that circulates coolant through the system

CONDENSATE PUMP: A small pump used with high efficiency furnaces or other appliances that create significant condensation. It activates when water collects to a certain level and pumps it out to a drain.

CONDENSER: The outdoor part of an air conditioning system that pressurizes refrigerant to cool it by changing it from a vapor to a liquid.

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

DRAIN (CONDENSATE) LINE: A drain required by a dehumidifier, high efficiency furnace, or similar appliance to carry away condensation.

EVAPORATOR: A system of coils in an air conditioning system that, when filled with cold refrigerant, cools the air around it. The evaporator is inside the plenum on the furnace or air handler.

PACKAGE UNIT: Equipment in, which all heating and cooling components are located in one cabinet.

PLENUM: A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.

REFRIGERANT (FREON): The liquid used to absorb and transfer heat from one part of the outdoor unit and the indoor unit.

REFRIGERANT LINES (LINE SET): Copper lines used to transfer the refrigerant between the outdoor unit and the indoor unit.

RETURN SYSTEM: An assembly of connected ducts, air passages, or plenums and fittings through which air from the spaces to be conditioned is conducted back to the heat exchanger.

SPLIT SYSTEM: A home comfort system that uses an indoor and outdoor component to deliver comfortable air to a living environment. The indoor coil is the device used for transferring heat from indoors to outdoors (or the reverse in the case of a heat pump in heating mode). Most modern systems are designed to achieve maximum efficiency when the indoor unit is properly matched with the outdoor unit. For best results, be sure to replace both indoor and outdoor units.

THERMOSTAT: A temperature measuring device used to control the operation of home comfort systems to maintain a comfortable temperature within the house. Programmable thermostats allow you to program different temperatures for different times of the day.

UPFLOW: 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.​