Found in duct work and in older gas and oil furnaces exhaust systems, this movable plate opens and closes to control airflow. Dampers can be used to balance airflow in a duct system. They are also used in zoning to regulate airflow to certain rooms.

Abbreviation for Decibel. Refer to Decibel.

Abbreviation for (Direct Current electricity). This type of electricity (as opposed to Alternating Current, or AC) flows in one direction only, without reversing polarity.

Abbreviation db, this term describes the relative loudness of sound. Refer to “sound rating number” as it applies to air conditioning equipment.

Also referred to as Defrost Cycle. The process of removing ice or frost buildup from the outdoor coil during the heating season.

A device used to remove moisture from indoor air.

To remove moisture from indoor air. Air conditioning helps to dehumidify the air, and it can be done separately with a dehumidifier.

Abbreviation for Department of Energy. The U.S. federal agency that sets HVAC industry efficiency standards and monitors the use of energy sources.

A type of furnace that takes in air at its top and discharges air at the bottom.

A pipe or closed conduit made of sheet metal, fiberglass board, or other suitable material used for conducting air to and from an air handling unit.

This can also be referred to as Supply and/or Return. A pipe or conduit through which air is delivered. Ducts are typically made of metal, fiberboard or a flexible material and is insulated. In a home comfort system, the size and application of ductwork is critical to performance and is as important as the equipment.