HVAC Terms Courtesy of Rockport, Texas Allen Air Conditioning & Electrical
The HVAC industry uses unfamiliar acronyms and industry terms. This HVAC dictionary will help you navigate the most common terms you’ll come across during your buying decision. We hope this will help your HVAC related research or issues.
Alternating Current also known as AC: A type of current where the polarity is perpetually reversing, causing the directional flow in a circuit to reverse at regular intervals.
Air Conditioning Contractors of America also known as ACCA
Acoustical – Relating to sound, the science of sound, or a sense of hearing.
Annual Fuel Utilization Efficiency also known as AFUE – A measurement used to rate furnace efficiencies by dividing the ratio of heat output by heat input.
American Gas Association, Inc. – Also known as AGA
Air Conditioner – A device that changes humidity levels, temperature or quality of air inside a building.
Airflow Volume – This is the amount of air circulated in a space and is measured in cubic feet per minute or cfm.
Air Handler – The fan-blower, filter and housing system parts.
Air Conditioning, Heating and Refrigeration Institute – Better known as AHRI
American Society of Heating, Refrigeration and Air Conditioning Engineers – Better known as ASHRAE
British Thermal Unit or BTU – Measures the amount of heat required to raise or lower the temperature of one pound of water one degree Fahrenheit.
British Thermal Units per hour – BTU/h
Burner – The device that facilitates the combustion of air and gas.
Burner Orifice – The opening in the burner through which the gas or fuel passes prior to combustion.
Capacity – HVAC capacity is the output produced by the heating or cooling unit and is measured in BTUs per hour.
Celsius – A temperature scale that registers the freezing point of water as 0° and the boiling point as 100° under normal atmospheric pressure.
Cubic Feet per Minute or CFM – 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 vapor to liquid.
Condenser Fan – A fan that passes air over the condenser coil to facilitate the removal of heat from the refrigerant.
Canadian Standards Association – Better known as CSA
Direct Current or DC – A type of electrical current that only flows in one direction.
Damper – Found at the exit point of duct work, this plate usually contains grates that can be opened or closed to control the flow of air into a zone.
Degree-Day – Calculated by subtracting the average outdoor temperature for an area from 65º Fahrenheit. This measurement is used to estimate the amount of heating or cooling a home or building will need.
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.
Department of Energy – Better known as DOE
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.
Duct work – A network of metal, fiberboard or flexible material flowing throughout a space which delivers air from an HVAC unit to the respective zones of a home or office.
Energy Efficiency Ratio – Better known as EER
Environmental Protection Agency – Better known as EPA
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 air flow.
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.
Gas Appliance Manufacturers Association – Better known as GAMA
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.
Heat Transfer – Moving heat from one location to another.
Heating Seasonal Performance Factor or HSPF – 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.
Ignition – Elevating the temperature of a substance to the point of causing a combustion reaction.
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.
North American Technician Excellence or NATE – is the only non-profit, independent, national certification and testing program for HVAC/R technicians accepted by the entire industry.
National Energy Council / National Electric Code – Better known as NEC
National Electrical Manufacturing Association – Better known as NEMA
Orifice – An opening or hole.
Package Unit – A heating and cooling system contained in one outdoor unit.
PSI – Pounds per square inch
PSIA – Pounds per square inch, absolute
PSIG – Pounds per square inch gauge
PVC – Polyvinyl chloride; a type of plastic.
Reciprocating Compressor – A type of compressor used in cooling systems to compress refrigerant by using a piston action.
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 or Seasonal Energy Efficiency Ratio – A rating system developed by the U.S. Government to indicate the efficiency level of cooling equipment.
Self-contained System – A package unit.
Sensible Heat – Heat added or subtracted that causes a change in temperature.
Sensor – A device that reacts to a change in conditions.
Split System – An outdoor unit combined with an indoor unit.
Thermostat: Sensors that monitor and control the output of an HVAC system.
Thermostatic Expansion Valve: A device that creates a constant evaporator temperature.
Ton: One ton is 12,000 BTUs per hour.
Upflow Furnace – A furnace that pulls in air from the bottom 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.
Wet Bulb Thermometer: A thermometer that measures the relative humidity in the air.
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.
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