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What Size Air Conditioner Do I Need?

If you don’t already have an air conditioning unit or system or you’re thinking about upgrading your existing system, determining what size air conditioner you need can be a real headache. If you go online to research and determine what you need, you can easily get confused by jargon and unfamiliar terms.

And in the end, you might be left exactly where you started, still wondering “What size air conditioner do I need? Hopefully, we can clear up some of the confusion for you.

Size isn’t everything

Many people buy an oversized air conditioner thinking it will provide better or faster cooling. The problem with that line of thought is that an oversized AC unit or system is actually less effective and wastes a lot of energy. And that can translate to higher energy bills every month.

What a lot of people don’t realize is that air conditioners remove both heat and humidity from the air. If the unit is too large, it will short cycle, meaning it will cool the area quickly and shut off. This prevents it from removing a large chunk of the humidity that contributes to your discomfort.

Oversized air conditioners leave you with a room that has a damp, clammy feeling. In contrast, a properly sized unit will remove humidity as it cools, providing you with a comfortable living space to relax in.

What about BTUs?

When considering air conditioning size, you’ve no doubt seen the letters BTU that appear on every unit’s description. But what does that mean? BTU stands for British thermal unit. One BTU equals the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.

Sure, the name’s a little weird, but knowing what BTUs are will help you find an AC unit or system that’s appropriate for the space you want to cool.

Without confusing you further, you also need to keep the word “ton” in mind, especially if you’re trying to cool larger areas. There are 12,000 BTUs to a ton, so if a manufacturer’s model number says, for example, it’s a 24,000 BTU unit, that means it’s a two-ton system. So, 18,000 BTUs would be 1.5 tons, 36,000 BTUs would be 3 tons, etc.

Calculating size

An easy way to calculate the size of the AC you need is to determine the square footage of space you want to cool and multiply the total by 25 BTUs. This allows for ample cooling and lets the AC work long enough to also reduce humidity.

For example, let’s say you only want to cool one room measuring 12’ x 25’. Take the product of 12’ x 25’ to get a total of 300 square feet. Then multiplying 300 square feet by 25 BTUs means you need 7,500 BTUs of cooling capacity.

If the needed cooling capacity falls somewhere between tons, what do you do? What size system do you get? The answer depends on a number of variables such as your insulation, the type and number of windows, number of stories, construction type, and more.

A general rule of thumb is that if your home is well insulated and has newer style windows, you can select the smaller size system that falls within your total square footage. On the other hand, if your is poorly insulated and has older windows and/or an abundance of windows, you should select the larger system.

In-wall units vs. window air conditioners

If you don’t have central air conditioning, the two most common options for cooling are in-wall and window units. A wall-through unit is installed through a customized hole through an exterior wall. Because they require cutting a hole in your wall, it’s best to hire a professional to install an in-wall unit.

Window units, on the other hand, don’t require any alterations. You just need to follow the manufacturer’s instructions for mounting it securely to an appropriate window. However, window units are often less durable and less efficient than in-wall or central air conditioners. But they can be a good choice for supplementing an existing central HVAC system or for cooling small spaces.

That said, all kinds of modern air conditioners are much more energy-efficient than models from even a few years ago. So you should be able to enjoy significant energy savings with any new air conditioner.

Contact us for more information

We hope this guide has proved useful in helping you determine what size air conditioner you need. If you have additional questions don’t hesitate to contact Pearson Plumbing, Heating/AC at 815-398-8312.

And if you’re in need of air conditioning repair in Rockford, we’re more than happy to help. Give us a call today to learn more about your options or to schedule a service call.

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