Selecting a reliable brand and choosing the best size is equally important when shopping for a window air conditioner or portable air conditioner. Size refers not to the physical dimensions of the unit, but rather to the capacity. The cooling capacity is measured in British Thermal Units (BTU) and generally models range from 4 000 to over 20 000 BTU. Larger spaces would obviously require a unit with a higher BTU. People often opt for an air conditioner with a much too high BTU, believing that it will be more effective in cooling down a room. Be aware that bigger is not always better as an oversized unit will cost more to use and would not be as effective in dehumidifying the air, causing a ‘clammy’ feeling. An oversized air conditioner can short cycle, meaning the compressor cycles on and off repeatedly, causing fuses to fail and circuit breakers to trip and compressor overloads to stop working. Air quality is also compromised when using a unit that is too big for the room and may give rise to allergic reactions. Buying a too small unit will also prove to be inefficient and a total waste of money. When calculating the load that the unit will have to handle, Johannesburg Air Conditioners makes use of a software program and thus we are more than capable of advising you on the best possible size unit for your needs. Certain shady suppliers will try to sell you the air conditioner with the highest rated BTU accompanied by a dehumidifier. A correctly sized air conditioner will successfully cool and dehumidify the room.
The first step in establishing the correct size air conditioner is to measure the room where it will be operating; multiply the length by the width in meters. You will also need to ascertain whether the room is sunny or shaded and note if it will be installed in a kitchen.
Contact a specialist at Johannesburg Air Conditioners to avoid making the mistake of purchasing a too big or too small air conditioner.

Below are just some of the terms you will encounter when shopping for an air conditioner:

• Amperage: Refers to the amount of electrical energy or current flowing through an appliance at any given time. This figure normally ranges from 5 to 15 amperes on regular air conditioners and 12 to 15 amperes on industrial size units. A dedicated electrical line is needed if the unit’s amps exceed 15 amperes, as the standard circuit in a room is rated at 15 amperes.
• Dehumidification: This measurement indicates the amount of moisture removed from the air by the unit, typically ranging from about 500 ml per hour to 5000ml per hour. If you live in a high-humidity area it is better to choose a unit with a higher rated dehumidification.
• Efficiency: The Energy Efficiency Rating or EER is calculated by dividing the BTU (cooling output) by the power consumption in watt-hours. A higher EER means lower electricity bills.

New features on selected models and brands include energy saving, automation and improved air quality. Some of these features can be deemed as essential by certain individuals, and others are just nice to have.

• Energy-saver switch: Usually an air conditioner fan runs continuously, even when the compressor is stopped. An energy saving switch saves you money by turning the fan off when the thermostat turns off the compressor.
• "Check filter" light: Filters need to be cleaned or replaced from time to time. This nifty light will remind you when it is time to check the filters.
• Oscillating vents: These make the air flow from side to side in order to cool the room more evenly and swiftly.
• Remote control: You will need this if you would like to be able to adjust the temperature from anywhere in the office or room. Particularly helpful in the middle of the night.
• Sleep mode: Avoid night-time chills with this feature that slightly raises the room temperature at night.
• Timer: You can set the air conditioner to automatically turn on or off so that the room is the preferred temperature before your arrival.
• Ventilation/exhaust: Allows fresh outside air to circulate in the room.
• Manufacturer's warranty: The warranty differs between brands but is normally for a period of one or two years and covers parts and labour.