HVAC Terms
Below are some of the most common HVAC industry terms for your reference.
ACCA: Air Conditioning Contractors of America – www.acca.org
AFUE (Annual Fuel Utilization Efficiency): A measurement used to rate furnace efficiencies by dividing the ratio of heat output by heat input.
Air Conditioner: Assembly of equipment that changes humidity levels, temperature or quality of air.
Airflow Volume: Measured in cubic feet per minute (cfm), this is the amount of air circulated in a space.
Air Handler: Parts of a system including the fan-blower, filter and housing.
AHRI: Air Conditioning, Heating and Refrigeration Institute
ASHRAE: American Society of Heating, Refrigeration and Air Conditioning Engineers
BTU: British Thermal Unit. Measures the amount of heat required to raise or lower the temperature of one pound of water one degree Fahrenheit.
BTU/h: The number of BTU’s per hour
Burner: The device that facilitates the combustion of air and gas.
Capacity: HVAC capacity is the output produced by the heating or cooling unit and is measured in BTUs per hour.
CFM (Cubic Feet per Minute): A measurement of airflow volume.
Charging a System: Adding coolant, or refrigerant, to an HVAC system.
Compressor: A pump that increases the pressure of gas.
Condensate: Vapor that is turned into a liquid as its temperature is lowered.
Condenser Coil: Also an outdoor coil. A device that removes heat from the refrigerant allowing the refrigerant to be converted from gas to liquid.
Condenser Fan: A fan that passes air over the condenser coil to facilitate the removal of heat from the refrigerant.
Damper: Found at the exit point of ductwork, this plate usually contains grates that can be opened or closed to control the flow of air into a zone.
Dehumidifier: A device that removes humidity, or moisture, from the air.
Diffuser: A grille over an air supply duct with vanes that distribute the discharging air in a specific pattern or direction.
DOE: Department of Energy
Downflow Furnace: A furnace with an intake on the top and an air discharge at the bottom.
Drain Pan: Also a condensate pan. As the refrigerant vapor is liquefied, the drain pan collects the condensate and funnels it to the drain line.
Dry Bulb Temperature: The temperature as measured without the consideration of humidity.
Ductwork: A network of metal, or flexible material flowing throughout a space which delivers air from an HVAC unit to the respective areas of a home or office.
EER: Energy Efficiency Ratio
EPA: Environmental Protection Agency
Expansion Valve: A valve that meters the levels of refrigerant through a temperature or pressure control.
Evaporator Coil: Also an indoor coil. A device that is designed to absorb heat in the air in order to change the liquid refrigerant that flows through it into a vapor.
Fahrenheit: A temperature scale in which water freezes at 32 degrees and boils at 212 degrees at normal atmospheric pressure.
Fan: A device that creates airflow.
Filter: A device that acts like a strainer to remove dirt or undesired particles.
Flue: A vent that removes the byproducts of combustion from a furnace.
Furnace: The major component in heating a home. A device that facilitates the combustion of fuel and air to create heat.
Fuse: A delicate metal strip connecting two parts of an electrical circuit. This strip breaks, or melts, in the event of excess electrical charge, breaking the electrical circuit.
Heat Exchanger: A device through which heat is transferred to a cold area or surface.
Heat Gain: The amount of heat added or created in a designated area.
Heating Coil: A coil that acts as a heat source for a heating system.
Heat Loss: The amount of heat subtracted from a designated area.
Heat Pump: A device used for either the heating or cooling of a space by transferring heat between two reservoirs.
HSPF (Heating Seasonal Performance Factor): This factor rates the efficiency of the heating portion of the heat pump.
Humidifier: A device that adds humidity, or moisture, to the air.
Humidistat: The device that measures humidity and turns the humidifier on and off.
Humidity: Dampness in the air caused by water vapor.
HVAC: Heating, Ventilation and Air Conditioning
Ignition: Elevating the temperature of a substance to the point of causing a combustion reaction.
Insulation: Protective material that slows down the transfer of heat.
Kilowatt (kW): 1,000 watts.
Latent Heat: A type of heat that when added to an area produces an effect other than an increase in temperature.
Media: The fine material of a filter that traps dirt, dust, mildew or bacteria.
NATE: North American Technician Excellence – Leading Certification in the HVAC industry.
Package Unit: A heating and cooling system contained in one outdoor unit.
PSI: Pounds per square inch,
PVC: Polyvinyl chloride; a type of plastic.
Refrigerant: A chemical that condenses from a vapor to liquid and, in the process, decreases in temperature.
Refrigerant Charge: The amount of refrigerant in a system.
SEER (Seasonal Energy Efficiency Ratio): A rating system developed by the U.S. Government to indicate the efficiency level of cooling equipment.
Sensible Heat: Heat added or subtracted that causes a change in temperature.
Supercooled Liquid: Liquid refrigerant cooled below its saturation point.
Subcooling: Creating a drop in temperature by removing sensible heat from a refrigerant liquid.
Superheated vapor: Refrigerant vapor heated beyond its saturation point.
Superheating: Creating a rise in temperature by adding heat energy to a refrigeration vapor.
Thermostat: Sensors that monitor and control the output of an HVAC system.
Thermostatic Expansion Valve: A device that creates a constant evaporator temperature.
Ton: The unit of measurement for air conditioning system capacity. One ton of air conditioning removes 12,000 Btu’s of heat per hour from a home. Residential homes air conditioning systems usually range from 1 to 5 tons.
Upflow Furnace: A furnace that pulls in air from the bottom or side and releases it through the top.
Vacuum: A space where the pressure is significantly below that of standard atmospheric pressure.
Volt: A unit of electro-motive force.
Voltage: The force pushing electrical current along wires and cables.
Watt: The unit of electrical power equal to the flow of one amp at a potential difference of one volt.
Zoning: A system that divides a home, office or space into different regions in order to better control the temperature and effectiveness of a heating and cooling system.