How does an air conditioner work?

Air conditioning systems work by moving heat from inside your home/office to the outside. In a mid-wall/high-wall split type air conditioning system air is drawn into the Indoor unit through the return air grille. The return air passes through the evaporator coil and then back into the room/area. The coil is connected to the condenser, the unit that is mounted outside, with copper piping/tubing

The refrigerant is then pumped from the condenser to the evaporator coil. As the refrigerant passes through the inside of the evaporator coil, warm air from inside passes over the outside of the coil. Because the refrigerant is cooler than the warm air, the refrigerant absorbs heat from the air. The refrigerant is then sent outside to the condenser unit. When the warmed refrigerant is in the condenser unit it is compressed by the compressor; the compression of the refrigerant causes it to boil. As the refrigerant boils it gives off the heat it picked up from inside your home. The refrigerant is then passed through the coil in the condenser unit where it gets cooled again and is ready to go back inside to pick up more heat and continue the process

As this whole process is going on both the temperature and relative humidity in your home/office are lowered. The relative humidity level drops because cooler air cannot hold as much moisture as warmer air. As the air cools, it gives up some moisture which is collected in the base of the evaporator coil and is then drained away through the drainage pipe to the outside
When a heat pump air conditioning unit is in heating mode the flow of the refrigerant is reversed and the cold is dumped on the outside and the heat is dumped on the inside.
Some heat pump units have as high as 4:1 heat to power use ratio. However on average most units have around 3:1 ratio and some as low a 2,5:1 ratio.

This means that a heat pump air conditioner is more than 3 times more energy efficient that an electrically driven heating device, such as a fan heater or oil heater or under floor heating etc.
This thus makes air conditioners far more environmentally friendly than just about any other type of heating or cooling system

What is the Energy Efficiency Rating?

The EER or energy efficiency rating measures the air conditioner’s energy consumption and efficiency. A high EER rating means less energy is being consumed and the less it costs to run.

What is the Coefficient of Performance Rating?

The COP or coefficient of performance rating measures both the air conditioner’s energy consumption and cooling/heating output. A high COP rating means less energy is being consumed and the less it costs to run.

What size air conditioner do I need?

The cooling capacity of an air conditioner is measured in British Thermal Units (btu) The capacity you require depends fore mostly on the size of the room you need to cool. In South Africa we use an average of approximately  500 btu per square metre for the total/sealable area, with a standard 2,5m ceiling height. There are other factors affecting the heat load in an area such as the size of the windows, direction of the sunlight, the number of people in the area at any given time, types of equipment and components and other heat generating equipment etc If an air conditioner is too small for am area it will not cool adequately. The unit will use far more power, have a shorter life span and in the end cost you far more than the correct size unit would. If you buy one that is too large, the air conditioner will cool the room before it dehumidifies and this can leave you feeling clammy. The unit will also use far more power than is needed and the life span of the unit will also be shortened, and in the end will cost you far more. For larger areas, sometimes/often two small units are more efficient than one large unit.

What should I look for in an air conditioner?

A recent study done, of over 3000 interviewees indicated the following preferences.
1. The most important factor is the noise of the indoor unit, especially for units used in bedrooms.
2. The next on the list was the physical dimensions of the indoor unit, the price of the unit then the manufacturers warranty on the unit.
3. Closely followed were the added/extra health/ filtering systems/features, the aesthetics/looks and design of the unit. The overall running cost of the unit was also a factor
4. Lastly the brand name and noise of the outdoor unit.

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