HVAC Glossary
Joseph's Heating and Air

Learn About HVAC Jargon

Understanding the various terms and acronyms related to heating, ventilation, and air conditioning can be quite a challenge. That's why we've compiled this comprehensive glossary to help demystify the technical jargon for you. Whether you're a homeowner seeking to understand more about your system, or you're exploring options for upgrades and maintenance, our glossary is designed to provide you with clear and concise definitions of the most commonly used HVAC terms. Dive in to become more informed about your heating and cooling system, and feel free to contact us if you need further explanations or personalized assistance.

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HVAC Glossary


A kind of electrical current that constantly switches direction, making the flow of electricity in a circuit change back and forth regularly.

A group dedicated to supporting over 60,000 professionals and 4,000 businesses involved in creating better indoor environments and energy services. Their website can be found at www.acca.org

Concerns anything related to sound, including its production, transmission, and effects on hearing.

Annual Fuel Utilization Efficiency is a standard for measuring how efficiently furnaces convert gas or oil into heat, by comparing the amount of fuel converted to heat to the total fuel input.

American Gas Association, Inc. A national organization representing the interests of companies providing gas delivery services.

The Air-Conditioning, Heating, and Refrigeration Institute (AHRI) represents manufacturers in the HVACR sector, focusing on ensuring high standards for equipment performance and efficiency.Their website can be found at www.ahrinet.org.

An appliance designed to control the air temperature, humidity, and purity within a space.

The total volume of air that moves through a space, typically measured in cubic feet per minute (cfm).

The component of an air conditioning system located inside the building that includes the fan and heating/cooling coils.

American Society of Heating, Refrigerating and Air-Conditioning Engineers is an international organization devoted to the advancement of heating, cooling, and refrigeration technologies and sustainability. Their website can be found at www.ashrae.org


A British Thermal Unit is a unit of heat defined as the amount needed to raise the temperature of one pound of water by one degree Fahrenheit.

The measurement of heat transfer rate over time.

A component in heating systems where fuel is mixed with air and ignited to produce heat.

The precise opening through which fuel is sprayed into the burner for combustion.


The maximum output or heating/cooling power an HVAC system can provide, usually measured in BTUs per hour.

A scale for measuring temperature where water freezes at 0 degrees and boils at 100 degrees under standard atmospheric conditions.

The rate at which air flows into or out of a space.

The process of adding or refilling refrigerant in an HVAC system.

Part of an HVAC system where refrigerant evaporates or condenses, facilitating heat exchange.

A mechanical device in HVAC systems that increases the pressure of the refrigerant to move it through the cooling cycle.

The moisture that drips from air conditioning components as a result of cooling warm air.

Usually located outside, it expels heat from the refrigerant, turning it from gas to liquid.

A fan that accelerates the movement of air over the condenser coil, facilitating the removal of heat from the refrigerant.

An organization that develops standards for a wide range of products and services in Canada.


Electrical current that flows in only one direction.

A movable plate in ductwork that controls airflow direction and volume.

A measure used to estimate the heating or cooling needs based on the difference from a base temperature, typically 65°F.

A device that removes excess moisture from the air.

An air distribution outlet designed to disperse airflow in desired patterns or directions.

The U.S. federal department responsible for policies regarding energy and safety in handling nuclear material.

A furnace design where air enters the top and heated air exits from the bottom.

A tray designed to collect condensation from the HVAC system and direct it away from the equipment.

The temperature of air measured without considering its moisture content.

The system of ducts used for the distribution of air in heating, ventilation, and air conditioning (HVAC) systems.


A measure of the efficiency of an HVAC system's cooling performance under specific conditions, calculated as the ratio of cooling output to electrical input.

A program by the U.S. Environmental Protection Agency (EPA) that identifies and promotes energy-efficient products and buildings.

A ratio that measures the cooling efficiency of air conditioners and heat pumps by comparing the cooling capacity to the power input.

A component of an HVAC system where refrigerant absorbs heat and evaporates, causing cooling of the air.

A device in a refrigeration system that controls the flow of refrigerant into the evaporator coil.


A temperature scale where water freezes at 32 degrees and boils at 212 degrees under normal atmospheric pressure.

A device that creates airflow through an HVAC system for the purpose of heating, cooling, or ventilating.

A device used to remove particles and contaminants from the air or refrigerant in an HVAC system.

A duct or opening that carries exhaust gases from a furnace, water heater, or boiler to the outdoors.

A heating unit that burns fuel or uses electricity to generate warmth for distribution throughout a building.

A safety device designed to protect electrical circuits from overload by melting and interrupting the circuit at a preset current level.


A trade association for companies that manufacture gas appliances.


A device that transfers heat from one medium to another without allowing them to mix.

The increase in temperature in a space, caused by factors such as sunlight, appliances, and occupancy.

A component that heats air as it passes over, typically found in furnaces or air handlers.

The transfer of heat out of a building, which can affect the heating requirements of a space.

A system that can provide both heating and cooling by moving heat from one area to another.

The movement of heat from a warmer object or area to a cooler one through various means (conduction, convection, radiation).

Measures the efficiency of heat pumps by calculating the ratio of heat output to electricity use over a heating season.

Adds moisture to indoor air, increasing humidity levels for comfort and health.

A control device that measures and regulates the humidity level in the air.

A control device that measures and regulates the humidity level in the air.


The process of initiating combustion in a furnace or burner to generate heat.

An arrangement allowing for the connection and support between different power systems during peak demands or emergencies.


A unit of power equal to 1,000 watts, used to measure electrical consumption.


The heat absorbed or released during a change of phase (e.g., from liquid to gas) without a change in temperature.


Material within a filter that traps and holds contaminants and particles from the air.

A HVAC system configuration that has been approved by the manufacturer for optimal performance and efficiency.


A certification organization for HVACR technicians, ensuring they meet industry-recognized standards for knowledge and competency.

A widely adopted set of safety standards for electrical wiring and installations.

An organization that sets standards for electrical equipment and promotes safety and reliability.


A small, precisely sized opening that controls the flow of fluid or gas.


A single outdoor HVAC unit that contains all necessary components for heating and/or cooling.

Tiny solid or liquid particles suspended in air or gas, which can be harmful to health and are regulated in emissions.

A space or chamber in an HVAC system that distributes air to various ducts.

A thermostat that allows users to set different temperatures for different times of the day or week to save energy.

A unit of pressure indicating the force per unit area applied in a direction perpendicular to the surface.

Measures pressure relative to a perfect vacuum.

Pressure measurement relative to the surrounding atmospheric pressure.

Pertaining to the study of the physical and thermodynamic properties of gas-vapor mixtures, often related to humidity and temperature.

A type of plastic commonly used in plumbing and ductwork for its durability and resistance to corrosion.


A heating system where heat is supplied directly to the floor of a space, often through pipes carrying hot water or electrical heating elements.

The transfer of heat energy through space or a material without the need for direct contact or a transferring medium.

A type of compressor in a refrigeration or air conditioning system that uses a piston to compress the refrigerant.

A substance used in cooling systems to absorb and release heat during the refrigeration cycle.

The specific amount of refrigerant required for an HVAC system to operate efficiently.


A modern compressor design known for efficiency, using two interlocking scrolls to compress refrigerant.

A measure of the cooling efficiency of air conditioners and heat pumps, indicating the amount of cooling produced per unit of electricity consumed over a typical season.

An HVAC system where all components are contained within one unit, typically installed outside the building.

The heat that causes a change in temperature of a substance but does not change its phase.

A device that detects changes in physical conditions such as temperature or humidity and converts them into signals that can be measured or controlled.

Refers to an HVAC motor that operates at only one speed, typically full power, until the desired temperature is reached.

An HVAC system with components that are separated into indoor and outdoor units, offering flexibility and efficiency.


A device that monitors and regulates the temperature of a space by controlling the operation of heating or cooling equipment.

A device in HVAC systems that regulates the flow of refrigerant to the evaporator coil, optimizing the refrigeration cycle.

A measure of cooling capacity, where one ton equals the cooling effect of melting one ton of ice in 24 hours, approximately 12,000 BTUs per hour.

An HVAC motor that can operate at two different speeds, allowing for more efficient temperature control and quieter operation.


A furnace that draws in cold air from the bottom and releases warm air at the top.


A space devoid of matter, or a condition significantly below atmospheric pressure.

An HVAC motor capable of adjusting its speed across a wide range to provide precise temperature control and energy efficiency.

The process of supplying fresh air to an indoor space and removing stale air, either naturally or through mechanical means.

The unit of measurement for electrical potential or electromotive force.

The difference in electrical potential that drives current flow through a circuit.


A unit of power representing one joule per second, used to quantify the rate of energy transfer.

A thermometer used to measure the lowest temperature that can be achieved by evaporative cooling, important for determining humidity levels.


A method of dividing a building into different areas for individual temperature control, improving comfort and efficiency.
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