Glossary of air conditioning terms

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magnifying glass and paperWhen you're shopping for an air conditioner, you may read or hear terms that you're not necessarily familiar with. Here's an easy-to-understand lesson on the A to Zs of A/Cs:

Air Flow Volume:

The amount of air that a cooling system circulates through your home, expressed in cubic feet per minute (CFM). A typical system requires 400 CFM per ton of cooling.

BTU (British Thermal Unit):

This is the amount of energy required to change the temperature of one litre of water one degree Celsius. For a smaller home, you would typically need 18,000 BTUs or 5.3 kilowatts of energy to cool the home effectively.

COP (Coefficiency Of Performance):

Refers to the cooling efficiency of an air conditioner. The higher the COP, the more energy-efficient the unit.


The part of the outdoor air conditioner that compresses and pumps refrigerant throughout the system.


The part of the outdoor central air conditioning system that removes the heat from the hot, gaseous refrigerant making it liquid again. A fan discharges the heat to the outdoors.

dBA (deciBel on the A scale) :

The system for rating the sound made by the outdoor unit of an air conditioner. The lower the number, the quieter the unit. The industry standard maximum sound for new air conditioning equipment is 7.6 dBA. For every .3 dBA lower, the sound is reduced by one half.

Evaporator Coil:

A network of tubes filled with refrigerant. The evaporator coil located inside the home removes heat and moisture as refrigerant changes from liquid to gas.

Inverter Technology:

Inverter technology allows a room to reach the required temperature more rapidly and up to 30% more efficiently than Constant Speed System. Inverter technology also eliminates the frequent stopping and starting often required by standard systems in order to maintain consistent temperature conditions.


Air conditioners are rated by their cooling or heating capacities in watts or kilowatts (1000 watts). This, the rate of heat transfer, is not to be confused with the energy input to the air conditioner (1 watt = 3.412 BTU/hr.). A bedroom of 15m² (160sq.ft.) would require an air conditioner with a cooling /heating capacity around 1650 watts (5600 BTU/hr.). Living Room An average living area 25m² (270sq.ft.) would need an air conditioner with a cooling and heating capacity around 3500 watts (12,150 BTU/hr.). As an approximate guide for sizing a room unit allow:

· 125watts (0.125kW) per square metre of floor area to be cooled in living areas;
· 80 watts (0.080kW) per square metre of floor area in bedrooms.


A fluid that changes from liquid to gas at low temperatures to remove heat and humidity out of the air. Common refrigerants include Puron and Freon..