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Air Conditioner Buying Guide

Is the warmer weather outside beginning to affect the comfort of the indoors? Then it might be time to purchase a portable air conditioning unit, and is here to help! Air conditioners can be a substantial purchase and the more information you have beforehand can ensure that you find the unit that is right for your needs.

Air Conditioning Basics

Air conditioners are constantly evolving to become more user-friendly and energy-efficient. How an air conditioner works is really quite simple. As warm air passed through the cold coils inside the air conditioner, moisture is removed. The water vapour then condenses on the coils and drains out of the air conditioner. The removal of moisture from the air reduces the humidity in your house, which is what makes the biggest difference in how cool it feels. Most, if not all portable air conditioners also use a hose to vent the hot air as it is removed. This hose usually vents through a window. As the air conditioner will also dehumidify, you will need to empty an inbuilt water tank from time to time, depending on the humidity. Split unit air conditioners are also available that do not require a hose, but do need a tube though a wall or window to a box placed outside, which increases the cooling power and capacity of the unit.

High-efficiency air conditioners are now coming onto the market in great quantities, and these are cheaper to run, and often better for the environment. They often also have variable speed options and many also have a fan setting that allows you to cool you house without using much electricity. The high speed setting cools the house very quickly but removes less humidity. The low speed setting cools more slowly but removes more moisture as the air is passing the coils at a slower rate, reducing the humidity.

Some air conditioners have electronic controls that provide a more accurate temperature reading. These units are more consistent in maintaining the comfort in your home because it makes it easier to find the perfect temperature, not too hot or too cold. Some models even include a built-in clock that can be set to start before you wake up in the morning or before you get home from work.


The size of the unit is perhaps one of the most important things to consider before you purchase an air conditioner. It is necessary to find one that is designed for the area that you wish too cool. If you choose one that is too big for your area, your home will actually feel damp and humid instead of cool and refreshing. The bill you will receive will be quite oversized as well.

The cooling capacity of an air conditioning unit is measured in BTUs (British Thermal Units). This is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Air conditioners vary in cooling capacities from 5,000 BTUs to 18,000 BTUs. Taking time to make some simple measurements will tell you which size is right for you. Below is a list of cooling capacities depending on room size. Remember that if your room is very sunny, you may need a slightly larger unit. Also, instead of trying to cool the entire house with one huge unit, you should consider buying several smaller units.

Area to Cool (sq. ft.) BTU's needed
100-250 5,000-6,000
250-400 6,000-8,500
400-550 8,500-11,000
550-875 11,000-15,000
875-1200 15,000-19,000
1200-1600 19,000-24,000
1600-1800 24,000-27,000
1800-2800 27,000-33,000

1 square foot = 0.09290304 Square Metre


Central and inbuilt air conditioners normally have a large box or control system on the outside of the building which is used to expel hot air and help the system run. However, these must be fixed into the building, and often cost many thousands of pounds. So, the portable units we sell are great for occasional use, during our hot, but temperamental summers, as they can be stored out of the way during winter, and cost a fraction of the larger units.

As the portable units will not have the large boxes outside, they will need a way to vent the hot air they produce. This is done in two ways. For smaller units, you need to place a hose out of the window, for split units, a small box needs to be placed outside on a windowsill or wall. Often on split units, the hose is detachable, so you can leave the box out side all year, but can store the unit away during the winter.

Therefore, when choosing your model, be aware of the room that you would like it to go in. Think about the following:

  • Is there easy access to the window from the floor?
  • Most exhaust hoses are between 1-1.5m long, will this be enough?
  • If the window is high, could the unit be rested on a table to raise its height?
  • If you live in a block of flats, will you be allowed to hang the box of a split unit on the building?

Just a quick point on the exhaust hose, the diameter is about 5 centimetres, but they will often have a thinner spout at one end for you to close the window around it.

Your electricity bill

Manufacturers have been developing units that are easier on the environment and your wallet. If you have an older air conditioner, you may be better off purchasing a newer model. The money you pay for the new unit will pay for itself in saved electricity within a short space of time. In addition, you can feel good about doing something better for the environment.

Other considerations

Aside from the basics, air conditioners come with many other features that can help you stay more comfortable during the summer. For example, some units come with louvers that act like air vents in your car, allowing you to direct air to where you want it. Others come with a remote control so that you don’t even have to get up to change the temperature.

In addition to becoming more efficient, air conditioners are also becoming less bulky. In the past, installing a unit could have you into see a doctor the next day. Many newer models are much easier to install and are also easier on the eye.

It is inevitable that you are going to have to clean your air conditioner; a unit with a dirty filter just won’t work properly. Fortunately, most units now come with filters that are easy to clean or entirely removable. Some units also come with a slide-out frame which gives you more convenient access to the unit without having to remove the entire casing.

Alternative Options

An alternative to using an air conditioner is to try an air cooler. Essentially, an air cooler is a “glorified fan”, meaning that the unit works much like a fan but use a combination of ice and water to cool small areas. They work by passing air though a net which is rolled in cold water, which you will need to fill, and replace once the water is warm. These units work best when pointed directly at the user. One benefit of an air cooler is that it only costs about as much as a fan to operate which eliminates large electric bills caused by air conditioners, as well as costing far less to buy. These may be a good option when placing a hose out of a window or wall is not possible.


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