Glossary of HVAC Terms

Are you finding yourself a bit confused by some of the "jargon" used in the HVAC industry? Our online glossary will help you understand the meaning of all those crazy buzz-words and acronyms. If you can't find the word or phrase you're looking for, send us a quick note and we'll add it as soon as we can.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
( displaying all words and phrases )

AC Alternating Current
A type of current where the polarity is perpetually reversing, causing the directional flow in a circuit to reverse at regular intervals.

ACCA
Air Conditioning Contractors of America.

Acoustical
Relating to sound, the science of sound, or a sense of hearing.

AFUE
Annual Fuel Utilization Efficiency. A measurement used to rate furnace efficiencies by dividing the ratio of heat output by heat input.

AGA
American Gas Association, Inc.

Air Conditioner
A device that changes humidity levels, temperature or quality of air.

Air Flow 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.

ARI
Air Conditioning 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.

BTUh
British Thermal Units per hour.

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.

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 vapor to liquid.

Condenser Fan
A fan that passes air over the condenser coil to facilitate the removal of heat from the refrigerant.

CSA
Canadian Standards Association.

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.

DC
Direct Current. A type of electrical current that only flows in one direction.

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.

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, fiberboard or flexible material flowing throughout a space which delivers air from an HVAC unit to the respective zones of a home or office.

EER
Energy Efficiency Ratio.

EPA
Environmental Protection Agency.

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.

Expansion Valve
A valve that meters the levels of refrigerant through a temperature or pressure control.

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.

GAMA
Gas Appliance Manufacturers Association.

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.

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 Coil
A coil that acts as a heat source for a heating system.

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.

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.

NEC
National Energy Council / National Electric Code.

NEMA
National Electrical Manufacturing Association.

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
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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