What Size Air Conditioner Do I Need for My Home?

AC System in Concord, North Carolina

Air conditioners last an average of 10-15 years when properly maintained. This means that most homeowners will need to replace their unit at least once. When it is time to replace yours, how do you determine if the size you have is right or if you should go bigger?

How Is Size Measured?

Size for air conditioners is measured in BTUs or British Thermal Units. This unit of measurement is the amount of energy required to raise the temperature of one pound of water by one degree. Essentially, the BTU rating for an air conditioner measures how much heat it can transfer out of a space in an hour.

Since a higher BTU rating means that an AC can rid a space of more heat in an hour, it is common to think that a bigger AC will cool your home more effectively. While this strategy might achieve your desired temperature more quickly, you would also risk freezing your system. In addition, you would prevent the system from dehumidifying your air, thereby reducing your overall comfort.

Understanding Why Size Matters

You have heard the story of Goldilocks and how she wanted the porridge that was just right. Your air conditioner is much the same way, needing to be just the right size for your home.

If your system is too small, it will run longer cycles than intended, driving up your utility costs. When a system is too large, it will run shorter cycles more frequently, also driving up your utility costs.

In addition to inflating your utility costs, an AC that is either too small or too large deals with a scenario that puts additional strain on the system and causes excessive wear and tear on the equipment. This sort of strain leads to more repairs and a shorter service life. That is why finding a system of just the right size for your house is so important.

Measuring Your Space

To begin the process of determining the size of system you need, start with the size of your home. The common measurement is for the amount of total square footage of space you want to cool.

If you live in a one-story home with a basic square or rectangle floor plan, you can probably simply multiply the width of your house by the length. However, most homes are not that simple, so you may need to do some calculating.

Start with considering the spaces serviced by your air conditioner versus those that are not. Remember to consider your attic, basement, and garage if they have vents. Also, your closets need to be factored in because they are not sealed.

Square Feet to BTUs

Once you have the size of the space you need to cool, you must convert that to BTUs. Unfortunately, there is no exact conversion to BTUs from square feet. However, there is a general rule of thumb you can use to get a sense of how many BTUs you need. For most homes, you can use the rate of 20 BTUs per square foot. So, multiply the size of your home by 20, and you have the rough capacity you’ll require.

If your home is 1,700 square feet, that means you will need a system with roughly 34,000 BTUs of output. However, this is just a rough guide with variables that may increase or decrease your needs.

Unlocking the Variables

There are several variables that may change the size of the air conditioner you should purchase. First, think about how many people are living in your home. If you have more than two residents, you may need to increase your BTUs. Generally, you want to increase the BTU output by about 600 for each person in addition to two.

You then need to consider your home’s external environment. If your home is in direct sun most of the day, you may need to increase your BTU output. On the other hand, if your home is mainly shaded, you may be able to reduce your BTU needs.

Finalizing the Decision

Before deciding which unit to purchase, consult with an air conditioning specialist to get the final calculation on the size. Ultimately, you’ll want to choose a company you can trust. When it comes to installing new air conditioners, people in Concord and throughout the Charlotte area have trusted All Temp Co., Inc Air Conditioning, Heating, Plumbing, & Electrical for over 30 years. In fact, our loyal customers trust us for all of their cooling and heating needs, including installation, repair and maintenance. Call us today to schedule a consultation with one of our air conditioning experts.


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