Understanding Air Conditioner Sizing: A Simple Guide

Whether you are having AC installed for the first time or replacing an existing air conditioner, you're bound to ask the question, "What size do I need?" The thing is, sizing air conditioners is not as straightforward as you might hope. At the same time, once you understand a few basic concepts, sizing your AC unit won't be that hard.

How Size Is Measured

When it comes to air conditioners, size is not measured in inches or even pounds. Instead, it is measured in BTU. The initials "BTU" stand for British Thermal Units. This is a measure of the cooling capacity of an air conditioner. The higher the number of BTUs an air conditioner delivers, the more powerful it is, or the larger it is. It would probably be more accurate to refer to BTUs as an indicator of an AC's capacity than its size. But for some reason, people have begun to use the term "size" in this case, and the HVAC industry often does the same.

Factors That Affect the Size You Need

It is pretty obvious that the larger your home is, the larger your AC should be. However, there are plenty of factors other than home size that affect your ideal AC size or capacity.

These factors include:

  • The average temperature in your area in the summer. 

  • Your home's layout. Is it a simple cube, or do you have multiple wings?

  • How well insulated your home is.

  • How cool you expect to keep your home.

Common Pitfalls in Choosing AC Size

Your best approach, when it comes to choosing an AC size, is to rely on your HVAC contractor's recommendations. They usually use formulas to calculate just what size you need based on the factors above. A common pitfall that customers fall into is asking for a larger AC than is recommended. This won't cool your home faster. In fact, the AC may shut off prematurely, resulting in uneven cooling, and your energy bills will likely rise.

Another mistake is choosing a too-small AC in an attempt to save money. This will cost you more money in the long run because the too-small AC unit will run overtime and use a lot of extra energy to cool your home. 

Hopefully this article has helped you better understand the intricacies of choosing a properly sized air conditioner. At the end of the day, your best bet is to follow your HVAC contractor's advice.

To learn more about air conditioning installation, contact a professional near you.