Air exchange rate: Air exchange rate is the rate at which air from outdoors replaces the air that exists inside a structure. Air exchange rate is measured in two ways.
Air changes per hour, or ACH, is defined as the number of times outside air replaces inside air within an hour. Cubic feet per minute, or CFM, measures the volume of outside air that replaces inside air.
Backup furnace: A backup furnace is installed as a secondary source of heat, usually in homes that rely upon geothermal systems or solar energy for primary heat sources.
British thermal unit: Most often referred to as BTU, the British thermal unit is a measurement of the amount of heat that is needed to raise the temperature of one pound of water one degree.
CFM/cubic feet per minute: A measurement of the volume of air that flows through any given space in one minute.
Combustion chamber: Combustion describes a series of chemical reactions that cause the release of heat. A combustion chamber in a furnace is an enclosed space where combustion takes place.
Condenser coil: The condenser coil is located within an air conditioner or heat pump. As the fan blows in air from the outside, refrigerant circulates through the condenser coil.
Outside air is then either released or collected, depending upon the unit’s current function.
Cooling capacity: The term cooling capacity is used in reference to air conditioning systems. It is a measurement of the amount of heat that the AC unit can remove from a room in a one hour time frame.
Draft: Draft refers to the movement of heated air, or combustion air, through a chimney.
Energy Star: Created by the Environmental Protection Agency, the Energy Star Program rates energy efficient products that are used in homes, including heating and cooling systems.