If you’ve ever gone out to purchase an air conditioner, you’ve likely seen their cooling capacity expressed in BTUs. If you’ve ever wondered what that means, you’re not alone. It’s short for British thermal units, which is a standardized measure of heat energy. Here’s how BTU ratings on AC systems work and why you should understand them before purchasing an air conditioner.

What’s a BTU Anyway?

A single BTU, or British thermal unit, is equivalent to the energy required to heat a single pound of water by one degree Fahrenheit at sea level. It’s a measurement with origins tracing back to the mid-1800s when indoor steam heating systems became common.

The measurement itself was the brainchild of a railroad engineer named Thomas Tredgold. He devised it as a way of measuring the power of a steam heater. Being British, Mr. Tredgold thought it only fitting to name the unit of measure after his home country.

Oddly enough, BTUs aren’t used in the United Kingdom these days. Nor are they used in most of the rest of the world. BTUs are almost exclusively used here in the United States, which is why you still see them on AC systems here today.

BTUs and Air Conditioners

At this point, you may be wondering what a measurement meant for heating systems has to do with air conditioning. And the answer is simple. It takes the same amount of energy to add a degree of heat as it does to remove it. So it’s also possible to measure heat removal by using BTUs as well.

On an air conditioner, the BTU rating you see tells you how many BTUs of heat the unit can remove from a room in an hour. That still doesn’t bring you any closer to understanding what the rating means in practical terms. For that, you need to know that it takes roughly 20 BTUs of cooling power to cool each square foot of space in your home.

With that information, you can use the BTU rating on an AC system to estimate how large a space it can cool. Of course, that’s still just a rough estimate. If you’re planning to use an AC in a room with high ceilings or large, sun-drenched windows, you’ll want to add some additional BTUs to compensate.

So, the More BTUs, the Better, Right?

Based on what you now know about BTUs and air conditioners, you might conclude that an AC with a higher BTU rating is always the right choice. That’s not true, though. Modern AC systems work best when they’re just the right size for the space you wish to cool. There are two main reasons for that.

First, if you use an AC system that’s too small for a given space, it will run constantly to try and keep up with the cooling demand. In most cases, it won’t ever succeed. On the other hand, if you select a unit that’s too large, the opposite will happen. It will cool the space so fast that it will end up turning on and off constantly. That leads to wear and tear that will cut the life of the AC short.

Those aren’t the only reasons that an improperly-sized AC is a bad idea, though. You should also know that they’ll cost you more to operate, too. Air conditioners operate at maximum efficiency only when they’re the correct size for the space you’re asking them to cool.

So, understanding the BTU rating on any air conditioning system you’re thinking of buying is essential. It’ll help you pick a unit that keeps you comfortable without bankrupting you in the process.

Consult an AC Expert

Now you know how important the BTU rating on an air conditioner is. It’s not the only thing you’ll need to consider when purchasing a new AC system, though. So, it’s always a good idea to consult an expert when the time comes for a new AC.

The team here at Kahn Air Conditioning would be happy to help you choose the perfect AC system for your Northridge, California, home and install it for you. We’ve served the community here since 1961, and you can trust every one of our NATE-certified installers and technicians to treat your home like they would their own. Whether you need AC installation, maintenance, or repair, you won’t find a more trustworthy provider anywhere — we’re sure of it.

Contact Kahn Air Conditioning for all of your air conditioning needs today!

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