Air Conditioning Glossary

A

Air Conditioner – A system that cools or heats indoor spaces by regulating temperature and humidity.

Air filtration – The process of removing dust, allergens, and pollutants from the air using filters in an HVAC system.

Airflow – The air movement within a system is crucial for efficiency and comfort.

Ambient Temperature – The surrounding environment’s temperature that impacts AC performance.

Annual Maintenance – A routine service check to ensure an air conditioning system runs efficiently and safely

B

BTU (British Thermal Unit) – A measurement of cooling capacity; the higher the BTU, the more powerful the unit.

Blower – The fan that circulates air throughout the system and into the room.

Bypass Damper – A component that helps regulate airflow in ducted systems to maintain balance.

C

Cassette system – A ceiling-mounted air conditioning unit that distributes airflow evenly, ideal for commercial and large residential spaces.

Compressor – The heart of an air conditioning system, responsible for compressing refrigerant and enabling cooling.

Condenser Coil – The coil where heat is expelled from the refrigerant to the outside environment.

Condensate Drain – A pipe that removes excess moisture from the system to prevent water buildup.

Consistent temperature control – The ability of an AC system to maintain a stable indoor temperature without frequent fluctuations.

Cooling Load – The cooling required to maintain a comfortable indoor temperature.

D

Ducted System – An AC system that distributes conditioned air through ducts to multiple rooms.

Dehumidifier – A feature or separate unit that removes excess moisture from the air to improve comfort.

Defrost Cycle – A process that eliminates ice buildup from the evaporator coil in heat pump systems.

Dual-Zone System – A system that allows different areas (zones) to be cooled or heated independently.

E

Energy Efficiency Ratio (EER) measures how efficiently an air conditioning unit converts electricity into cooling power.

Evaporator Coil – The coil inside the indoor unit where heat is absorbed from the indoor air.

Expansion Valve – A component that regulates refrigerant flow into the evaporator coil.

F

F-Gas certification – A qualification required for professionals handling fluorinated greenhouse gases in air conditioning and refrigeration systems. 

Fan Coil Unit (FCU) – A system that uses a fan and coil to circulate conditioned air in a space.

Filter – A component that traps dust, pollen, and debris to improve indoor air quality.

Freon – A familiar brand name for refrigerant used in air conditioning systems.

H

Heat Exchanger – A device that transfers heat from one medium to another, essential for cooling and heating.

Heat Pump – A system that can provide heating and cooling by reversing the refrigeration cycle.

HVAC (Heating, Ventilation, and Air Conditioning) – The overall system regulates indoor climate.

I

Indoor Unit – The part of a split system air conditioner inside the building.

Inverter Technology – A system that adjusts the compressor’s speed to improve energy efficiency and temperature control.

Insulation – Material used in ductwork and buildings to prevent heat loss or gain, improving efficiency.

K

kW – Kilowatt, a unit of power measurement indicating the energy consumption or output of an air conditioning system.

L

Load Calculation – The process of determining the correct size AC system for a space based on various factors.

M

Multi-Split System – An AC system connecting multiple indoor units to one outdoor unit.

O

Outdoor Unit – The part of a split system that houses the compressor and condenser coil.

Overcooling – When an AC system lowers the temperature excessively, leading to discomfort and energy waste.

R

Refrigerant – A chemical substance that absorbs and releases heat, enabling cooling in an AC system.

Refrigerant Leak – A fault where refrigerant escapes, reducing system efficiency and potentially harming the environment.

Return Air – Air drawn back into the AC system to be reconditioned and recirculated.

S

SEER (Seasonal Energy Efficiency Ratio) – A rating that measures the efficiency of an AC system over a season.

Smart Thermostat – A programmable thermostat that allows remote control and automated temperature adjustments.

Split System – A standard AC setup where the compressor is outside and the cooling unit is inside.

Supply Air – The system blows the conditioned air into a room.

System recommissioning – The process of testing, adjusting, and optimizing an existing HVAC system to restore efficiency and performance.

T

Thermostat – A device that regulates indoor temperature by controlling the air conditioning system.

Ton (Cooling Capacity) – A unit of measurement for AC capacity; one ton equals 12,000 BTUs per hour.

Two-Stage Compressor – A compressor that operates at two speeds to improve efficiency and comfort.

W

Wall-mounted unit – An air conditioning unit installed on a wall, commonly used for residential and small commercial spaces.

V

Variable Refrigerant Flow (VRF) – An advanced system that adjusts refrigerant flow to different areas based on demand.

Ventilation – Exchanging indoor air with fresh outdoor air to improve air quality.

Z

Zoning System – A system that allows different building areas to be heated or cooled separately.

Zero ODP Refrigerant – A refrigerant with zero ozone depletion potential, making it environmentally friendly.