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How Air Conditioners Work


Many people do not consider how air conditioners work until they are thinking of buying a system or their existing air conditioning system breaks down. How air conditioners work is contrary to accepted opinion that air conditioners produce cool air. In fact, air conditioners remove the heat from circulating air in the air-conditioned zone. The most similar appliance in operation is a refrigerator, except refrigerators only cool a small area and are obviously less powerful.

The first thing to know about how air conditioners work is they have three major components; condenser, evaporator and compressor. These three key components work together to keep moving the heat. In conjunction with the three major components, how air conditioners work is through around five different procedures – i) compression ii) condensation iii) expansion iv) evaporation and v) heat transfer.

A liquid refrigerant usually Freon is used as a heat exchanging medium. It enters into the compressor in a gaseous state. Similar to an air pump, compression squeezes the gas, which increases the pressure inside the gas molecules. This pressure causes collision of the molecules, which releases heat. This heated gas will flow into and through the condenser where the Freon cools and condenses into liquid form. The liquid then passes through a capillary tube into the evaporator. Next, the liquid transforms into a cold gaseous form and absorbs the warm air passing over the evaporator coils. The built in fan will then blow cool air from the air conditioning unit and circulate it in the room. The Freon gas then returns to the compressor and the cycle begins again.

Because an air conditioning system needs to be the right size for the area it is heating or cooling, it is not enough to know how an air conditioner works. You need to know how to calculate the right size of unit that will optimally heat and cool your home in the most efficient and energy saving manner. We recommend you allow out reputable team of engineers to calculate your air conditioning system size for you so that nothing is left to chance. It is such a pity when we are called in to put things right because the wrong calculations have been made and people find their systems are too hot, too cold, or cutting in and out. All of these problems and extra expense can be prevented by using a professional engineer.

Here we look at what is involved in choosing a system for your home.

What Size Air Conditioner Will Suit My Home?

You will need to work out the size of air conditioner you need by using mathematics. The calculations involve many measurements to input to the calculation. Here are the steps to take:

1) Measure the Floor

Each room that needs to be cooled will need to be measured. You need to bear in mind that hot air rises and cool air sinks. Measure the width and length of the room space and multiply together. This calculation will give you the square footage of your room. This result is multiplied by 337 because each square foot contains 337 BTUs. Next, the windows are measured on the south side of the home (the warm side). Each window must have the square footage calculated (width x height). Take the window square footage and multiply by 871 BTUs. Repeat this exercise for north side windows but use 166 BTUs in that calculation. Add the window results together.

2) The Human Factor

Because people take up space and cooled air they must be taken into account as each person generates their own particular BTU figure – approximately 400 BTU. Multiply 400 by the number of people living in the home. Make a note of this figure.

3) Lighting

Lights generate heat too so you will need to work out the number of watts for each light fitting and multiply by 4.25 BTUs. While 80-watt bulbs will not generate as much heat as 100-watt bulbs, the average across all light bulbs will be 425 BTU. Add the results of all light calculations together and note the result.

4) Appliances

If there are appliances running in the area to be cooled, you will need to check the wattage for the appliance and multiply 3.15 BTU. Always calculate the maximum wattage so there is not a risk of your air conditioner being underpowered. Keep a note of this figure as well.

Add together all of your results from your calculations – lighting, appliances, people and this will give you a BTU figure that your air conditioner will need to be able to handle.

As an exercise, the calculations will give you an idea of the size of air conditioner you need and will highlight how much energy you are using in the home – always a worthwhile exercise. If maths is not your strong point or you are unsure where you want your air-conditioned rooms, we will happily do the calculations for you and give you some options and competitive quotations.

Posted in: Latest News - On: 28th of April, 2013