Summary of Air conditioning

Summary of Air conditioning


  1. It is a process of controlling simultaneously four parameters, temperature, humidity, purity and velocity of air in a closed space. Air conditioning is cooling in summer, heating in winter with ventilation.


  1. Air conditioning is required for comfort, food preservation, for a better accuracy measuring instruments and in the manufacturing processes.
  2. Comfort Air Conditioning is of three types, namely, summer air conditioning, winter air conditioning and year round air conditioning.
  3. Human comfort is required in homes, offices and restaurants.
  4. Air conditioning is required in all types of vehicles, namely, cars, buses, trucks, trains and airplanes.
  5. Air conditioning is required in printing, drugs, rubber and textile industries for controlling conditions to result in more production with better quality.
  6. Air conditioning is found everywhere, namely, in shops, cinemas, hospitals, libraries, computer centers, beauty saloons, malls, telephone exchanges, data processing centers, mines and museums.


  1. Human comfort conditions are temperatures between 22 to 270C with relative humidity between 35 to 60 %, CO2 ≤ 600 ppm, CO≤ 25 ppm, odorless, virus free, fungus free and air velocity from 0.20 to 1.2 m/s.


  1. Air conditioning units are classified as central, unitary and window units.

Window units

Window units are up to 3 ton capacity. Unitary units are from 10 to 50 tons capacity and central air conditioning plants are for a cooling capacity of more than 50 tons. The main refrigerant used in window air conditioners and central air conditioning plants is R-22. The main refrigerant used in unitary unit is R-410A. Room conditions are changed to required comfortable conditions by employing processes of simple cooling, simple heating, heating and humidification, cooling and dehumidification .

Central air conditioning plant

Main components of central air conditioning plants are compressor, condenser, expansion valve, evaporator, fans and blowers, filters louvers and ducts. Fresh ventilation is also required in air conditioning to maintain requisite level of oxygen in the space being air conditioned.  Air conditioning normally deals with temperatures above 0C. Fan coil units and Air Handling Units are used in central air conditioning plants. Mainly there are two types of central air conditioning plants, namely, direct expansion type and chilled water systems. There are main supply, main return and branch ducts are used in the central air conditioning system.


Complete system of heating, ventilation and air conditioning is called HVAC.