HVAC TERMINOLOGY

Comprehensive HVAC Terminology List for Heating and Air Contractors

A

• Absolute Pressure: Pressure measured relative to a perfect vacuum.
• Accumulator: A tank in an HVAC system that prevents liquid refrigerant from entering the compressor.
• Air Balancing: Adjusting the HVAC system to ensure even air distribution.
• Air Conditioning (AC): A system that controls temperature, humidity, and air quality.
• Air Diffuser: A vent that evenly distributes air from the HVAC system.
• Air Handler (AHU): A unit consisting of a fan, heating/cooling elements, and filters to regulate air circulation.

B

• BTU (British Thermal Unit): A unit of measurement for energy, often used to describe heating and cooling capacity.
• Blower Motor: A component that circulates air through an HVAC system.
• Building Energy Management System (BEMS): A system that monitors and controls building mechanical and electrical systems.

C

• Capacitor: A device that helps start and run the compressor and fan motors.
• Carbon Monoxide (CO): A potentially dangerous gas that HVAC systems must vent properly.
• Chiller: A machine that cools water or a glycol solution for air conditioning purposes.
• Compressor: A key HVAC component that circulates refrigerant throughout the system.
• Condenser Coil: A coil where refrigerant releases heat and condenses from a gas to a liquid.

D

• Damper: A device that regulates airflow in ducts.
• Dehumidification: The process of removing moisture from the air.
• Ductwork: Tubes or passages used to deliver and remove air from the HVAC system.

E

• Energy Efficiency Ratio (EER): A measurement of cooling efficiency under specific conditions.
• Evaporator Coil: A coil where refrigerant absorbs heat, cooling the air.
• Expansion Valve: A device that controls the flow of refrigerant into the evaporator.

F

• Filter: A device that removes contaminants from air or refrigerant.
• Freon: A brand name for certain refrigerants used in HVAC systems.

G

• Gauge Pressure: Pressure measured relative to atmospheric pressure.
• Geothermal Heat Pump: A heat pump that uses the Earth's consistent temperature as a heat source or sink.

H

• Heat Exchanger: A device that transfers heat between two or more fluids or air.
• Heat Pump: A system that provides both heating and cooling by transferring heat.
• Humidifier: A device that adds moisture to the air.

I

• Indoor Air Quality (IAQ): The condition of the air inside a building concerning health and comfort.
• Insulation: Material used to prevent heat transfer and improve system efficiency.

L

• Latent Heat: Heat required to change the state of a substance without changing its temperature.
• Load Calculation: Determining the heating or cooling capacity needed for a building.

M

• Make-Up Air: Fresh air introduced into a building to replace exhausted air.
• Mini-Split System: A ductless HVAC system with separate indoor and outdoor units.

P

• Plenum: The air distribution box attached to the HVAC system.
• Programmable Thermostat: A thermostat that can be set to adjust temperatures automatically.

R

• Refrigerant: A chemical used in HVAC systems to transfer heat.
• Return Air: Air returning to the HVAC system after circulating through a space.

S

• SEER (Seasonal Energy Efficiency Ratio): A measurement of air conditioning and heat pump cooling efficiency over a season.
• Split System: An HVAC system with separate indoor and outdoor components.

T

• Thermostat: A device that controls the temperature by regulating HVAC operation.
• Ton: A unit of measurement for cooling capacity, equal to 12,000 BTUs per hour.

V

• Variable Speed Motor: A motor that adjusts its speed to meet the HVAC system's needs.
• Ventilation: The process of supplying fresh air to and removing stale air from a space.

Z

• Zoning System: A system that divides a building into zones with independent temperature controls.