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Air Conditioning 101

1. How air conditioners work:

Air conditioners absorb heat energy in one place (e.g. your home) and release that energy in another place (outside your home). This whole process requires an indoor unit (evaporator), an outdoor unit (condensor), copper piping to connect these units, electricity supply and communication wires between the two units. The piping circulates refrigerant that flows from one unit to another. This refrigerant absorbs the energy in one unit (e.g. indoors), transport it between the units and releases it through the other (e.g. outdoor unit).

2. The air conditioning process:

1. The indoor or Evaporator Unit
A fan built into this unit blows the hot indoor air over a heat exchanging coil through which cold refrigerant flows. The cold refrigerant absorbs this heat from the air and the cooled air is blown back into the room.

2. The Copper Piping
The refrigerant liquid (R22 or R410a) circulates through the indoor and outdoor units via the copper piping.

3. The Outdoor or Condenser Unit
Through the process of compression, the refrigerant gas is heated so that its boiling point increases. Heat obtained through the process of compression is released to the outdoor air by means of a fan which blows the outdoor air over a heat exchanging coil.

4. Completion of the cycle back at the Indoor unit
The cool, liquid refrigerant is decompressed, thereby enabling it to extract heat from the warm indoor air.


3. Other important air conditioning facts:

A fan built into this unit blows the hot indoor air over a heat exchanging coil through which cold refrigerant flows. The cold refrigerant absorbs this heat from the air and the cooled air is blown back into the room.

  • Btu’s – An air conditioners capacity is measured in British thermal units, or Btu’s. A Btu is the amount of heat required to raise by 1° the temperature of a pound of water in one hour. In AC jargon, Btu’s measure the amount of heat an air conditioning unit can remove from the room. As the Btu rating increases, so does the size, weight and cost of the air conditioner. Room air conditioners generally range from 9000–24,000 Btu’s. Matching Btu requirements to room size is important. The room(s) won’t cool efficiently if the Btu rating of the unit is low or too high for the size of the room. When calculating the Btu’s required for a room:
    • Use 400-500 Btu’s per square meters
    • Add 600 BTU/hr for every additional person in the room
    • Add 1000 BTU/hr for every appliance
  • Refrigerant – Refrigerant is a compound gas used in air conditioners. R22 has been used as the “standard” refrigerant for many years but has been found to be harmful to our planet. Most air conditioners still use the standard R22 refrigerant, but there is growing pressure on all manufacturers to phase out this harmful gas and replace it with the ozone friendly R410a refrigerant. Today clients have the option to choose between the two types of refrigerant.
  • Compressor – The compressor is motorised pump that drives the air conditioning unit. It is responsible for pumping refrigerant throughout the system. The com pressor is located in the outdoor unit, which is a huge factor keeping noise levels down. An Inverter compressor is designed to vary it’s speed as the demands in the room change. Inverter compressors are designed to soft start therefore causing no dips in power supply. Conventional compressors causes constant peaking on electricity supply, increasing energy use and ultimately electricity costs.
  • Energy usage – Most domestic air conditioners run on single phase electricity. The energy efficiency of an A/C is measured by an Energy efficiency Rating (EER). The EER is the ratio used to calculate the cooling capacity of a unit relative to its power consumption in Watt, calculated in BTU per hour divided by Watt. For example: Total net BTU is 9000 BTU/h & the net power is 1000 Watts: 9000 Btu per hour /1000 watt = 9 EER (BTU per Watt). The higher the EER value, the more energy efficient the unit will be.
  • Noise levels – Most indoor units have Noise levels below 50 db, which is very soft. Outdoor units should be rated below 58db.
  • Thermostat – The thermostat’s basic function is to regulate the operation of the AC. You set the AC to the desired temperature and the thermostat turns the AC on and off to maintain that temperature. AC’s are fitted with an electronic thermostat that detects the temperature levels and then electronically regulates the operation of the AC so that the selected temperature level is maintained.
  • Filters – Clean air is essential for efficient operation. Look for units with filters that can be easily cleaned or replaced.
  • Fan – The fan moves the air. A variable-speed fan combined with an adjustable thermostat is an effective cooling machine. Look for louvers that adjust up/down and right/left.

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