What Are Air Conditioning BTU’s?

May 14, 2021
AC System in Somerset, Kentucky

Air conditioners can be complex appliances, but what we can all appreciate is how good they are at cooling our homes. If you’ve been wondering what type of AC would be most appropriate for your space, it’s important that you learn about a term called BTUs.

What Exactly Is a BTU?

BTUs, or British Thermal Units, are a measure of energy in the form of heat. Several hundred years ago (in Britain as you’d expect from the name of the unit), scientists determined that one BTU is the amount of energy it takes to raise the temperature of one pound of water by one degree. One BTU is a very small amount. After all, our stoves heat quarts of water very quickly, and our microwaves and toasters can be very efficient as well.

When it comes to BTUs and air conditioners, it might not make sense at first. What do air conditioners have to do with heat? Well, air conditioners remove heat from indoor spaces. They take in hot air, remove the heat, and then blow the cooled air back into the space. The amount of heat that they can remove in an hour is measured in BTUs. Going back to the point we made earlier about how one BTU is a small amount of energy, it’s logical that air conditioners would have thousands or even tens of thousands of BTUs.

How Many BTUs is Ideal?

A very general rule is that 20 BTUs are required to effectively cool 1 square foot of space. Using that ratio, a 200-square-foot room would need an AC with 4,000 BTUs, and a 500-square-foot space would need an AC with 10,000 BTUs. Again, though, this is a generalized approach to BTUs. When you have a professional carefully assess your home, you’ll get a more exact number that takes into account various factors.

  • Layout of the space
  • Number of people using the space
  • How many windows and doors there are
  • How much insulation there is
  • How much shade there is

These can all play a role in determining what amount of BTUs you’d need. If you get a unit with not enough BTUs, it will struggle to do its job. It will likely need to be on almost all the time, and this excessive use could lead to excess wear and tear, not to mention increased utility bills. If you get a unit that has too many BTUs, this isn’t ideal either. That’s because it will do such a good job of cooling the air that it will only be turned on for a short amount of time. It will turn on, then off, and then back on, then off, and so forth. This is called short cycling, and it, too, can lead to problems.

Are Tons the Same Thing as BTUs?

When looking at whole-house air conditioners, you often see the term “tons.” In this case, tons don’t refer to weight. Instead, one ton is the same as 12,000 BTUs. This terminology is used because, historically, ice was used to cool down buildings. Experts figured out that one ton of ice would require about 288,000 BTUs to melt over the course of a day. Diving that number by 24 hours gives us 12,000 BTUs. Many larger homes can use 3-ton or 4-ton units. Those with multiple zones might use two 2-ton or 2.5-ton units.

A Local Source of Assistance

If you’re located in the Somerset area and need help with an AC installation, Jeffries Heating & Air + Plumbing is available to take care of your project. We enjoy working with people in our local community, and our dedication to service has earned us an A+ rating with the Better Business Bureau. Our organization has been screened and approved by Home Advisor, and we’re fully licensed. You can put your trust in us to handle everything properly. If you have questions at any time, feel free to bring them to our attention. We feel that one of our responsibilities is to keep our customers informed and educated, and you’ll find that we’re friendly, welcoming, and professional. Our team offers services related to plumbing, heating, and cooling. We can address issues that you may be facing, install new units or appliances for you, and perform tune-ups. Call us to set up your appointment or to discuss our services in greater detail.

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