Air Conditioning – Sizing

OLYMPUS DIGITAL CAMERAYou may be under the illusion that getting the size of your air conditioner right is not a very hard task. You just consider the size of your room and what you assume would work best for you room. Then you go out and buy and air conditioner and you are either happy with it or you really can’t tell the difference. However it is very essential that you get just the right size air conditioner for your room or house. Proper cooling will no one else but you happiest. Usually there are three sizes and people buy the one in the middle because, of course, you cannot possibly go wrong with that. But that is a clear mistake and there is in fact a size that is  meant just for you. Although you cannot be blamed because air conditioning is not an exact science. There are a lot of things that affect the way a system works or operates.

Let’s consider both cooling systems. If you have a central air conditioner that is too large for the place you intend to cool then you are probably in a worse off situation than if you had a smaller air conditioner. In this case your house will be cooled off extremely quickly and you will not be able to avail of the secondary benefit of cooling that your system offers. You will have to turn your air conditioner on and off more often and this might damage the system. Another downfall of having a cooling system that is too large is the fact that air conditioners are also meant to dehumidify the air. If the air conditioner cools the house off too fast and does not get a chance to remove all the moisture out from the air then you will have a rather uncomfortable house which is not an ideal situation at all. This can also happen for large buildings. Ever entered a store and felt like you walked into a refrigerator? That is because the air is being cooled too rapidly without the moisture being removed. This can be a great inconvenience but since the air conditioner is already bought there may not be much you can do about it. Although this happens in homes at a lesser degree and you may not even notice it, your air conditioner will not be cooling like it should be.

Then comes the problem of having an undersized air conditioner. Of course the first issue would be that the air is not cool enough. But this will mostly happen on days when it is very hot and you will not even feel the heat that badly. It just will not be as cool as on normal days. It usually not a noticeable quality unless you actually move from the inside to the outside and do not notice only a subtle difference in the temperatures.

And you will not even mind so long as you are kept relatively cooler than the weather outside. This also has the benefit that on a mildly humid day you will be kept very cool since the air conditioner removes all the moisture from the air since it takes a long time to cool. When comparing oversized and undersized air conditioners, it is always more beneficial to have an undersized air conditioner, since no matter the weather outside you will not be uncomfortable. You will always be kept cool and not too cold. You will obviously have to run it longer but that is not an issues when it comes to money since it is running at a lower power and therefore the energy consumption is relatively the same. Now though having an oversized or undersized air conditioner has both its pros and cons, neither of them is something that you want. You want an air conditioner that fits just nicely and cools well and does not give you any problems even if the weather is a bit too hot outside.

Taking for example a 15 foot wide by a 20 foot long room has 300 square feet of area. In this case you will have to multiply the size by 25 BTU and that will give you a 6000 unit BTU capacity limit. This is what you will look for in an air conditioner. If you happen to have a heavily shaded room reduce the BTU capacity by 10% and if you happen to have a very sunny room then increase it by 10%. If you have two or more people in a room then you will want to add 600 BTU per person. And if your kitchen produces a lot of heat then you will want to add a total of 4000 BTU. These are all technicalities to help you when buying an air conditioner. You can also ask a professional for advice.

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