HVAC - Heating, Ventilation, and Air Conditioning.

Air Handler - A device used to circulate and condition air.

Airflow - The movement of air through a system or space.

BTU - British Thermal Unit, a unit of heat energy.

Compressor - A mechanical device used to increase the pressure of refrigerant.

Condenser - A device used to release heat from refrigerant.

Ductwork - The system of ducts used to distribute air throughout a building.

Evaporator - A device used to absorb heat from a space.

Filter - A device used to remove particles from the air.

Furnace - A device used to heat air or water.

Heat exchanger - A device used to transfer heat from one fluid to another.

Heat pump - A device used to transfer heat from one location to another.

Humidity - The amount of moisture in the air.

Humidifier - A device used to add moisture to the air.

HSPF - Heating Seasonal Performance Factor, a measure of a heat pump's efficiency.

IAQ - Indoor Air Quality, a measure of the quality of air inside a building.

HVAC system - The collection of devices used to heat, cool, and ventilate a building.

Load calculation - A calculation used to determine the heating or cooling needs of a building.

SEER - Seasonal Energy Efficiency Ratio, a measure of an air conditioner's efficiency.

Split system - A system in which the indoor and outdoor units of an HVAC system are separate.

Thermostat - A device used to control the temperature of a space.

VAV - Variable Air Volume, a type of HVAC system that adjusts the amount of air delivered to each zone based on demand.

Zone - A specific area within a building that is controlled by its own thermostat or temperature sensor.

AHRI - Air Conditioning, Heating, and Refrigeration Institute, a trade association for HVAC manufacturers.

CFM - Cubic Feet per Minute, a measure of the volume of air flow in a system.

Chiller - A device used to cool water or other fluids for use in an HVAC system.

CO2 sensor - A device used to monitor the amount of carbon dioxide in the air.

Damper - A device used to control the flow of air in a duct system.

Dehumidifier - A device used to remove moisture from the air.

Energy Star - A government program that identifies energy-efficient products.

Fan coil unit - A device used to condition air in small spaces.

Geothermal - A type of HVAC system that uses the earth's natural heat to heat or cool a building.

Heat recovery ventilator - A device used to recover heat from exhaust air and use it to preheat incoming fresh air.

Heat strip - A device used to provide supplemental heat to an HVAC system.

Inverter - A device used to control the speed of a compressor motor in order to improve energy efficiency.

Load shedding - A technique used to reduce the load on an HVAC system during periods of high demand.

MERV - Minimum Efficiency Reporting Value, a rating system for air filters.

Packaged system - A type of HVAC system in which all components are contained in a single cabinet.

Refrigerant - The substance used to transfer heat in an HVAC systemScroll compressor - A type of compressor that uses two spiral-shaped scrolls to compress refrigerant.

SEF - Seasonal Efficiency Factor, a measure of a furnace's efficiency.

Static pressure - The force exerted by air against the walls of a duct.

Superheat - The amount by which the temperature of refrigerant exceeds its boiling point.

Thermostatic expansion valve - A device used to control the flow of refrigerant into the evaporator.

Ton - A unit of cooling capacity, equal to 12,000 BTUs per hour.

Variable speed - A feature that allows an HVAC system to adjust its output to meet changing demand.

Ventilation - The process of exchanging indoor air with outdoor air.

Water source heat pump - A type of heat pump that uses water as a heat source or heat sink.

Zoning - The process of dividing a building into multiple zones, each with its own thermostat or temperature sensor.

2-pipe system - A type of HVAC system in which the same set of pipes is used for both heating and cooling.