Previously known as Miles Service Cooling and Heating. Now part of the Air Tech family. Learn more

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What Size AC Unit Do I Need?

Looking for a new AC unit, whether it’s a replacement or part of new construction, can be a daunting task. Between all of the brands, models and a million different specifications, it’s easy to become overwhelmed because you most likely aren’t an AC installation expert.

Luckily, the team at Air Tech of Pasadena is full of experts that are ready to guide you through the many aspects of choosing a new AC, starting with the most important one: size.

What Exactly Is AC Size?

When it comes to AC size, HVAC professionals aren’t talking about the physical size of the unit. We’re actually talking about the amount of space that the unit can cool, which is measured in tonnage. When choosing a central air conditioner, it’s important to choose the correct AC unit size to ensure that your AC system will be able to provide adequate cooling throughout the house — even on the hottest Texas day!

Calculating AC Size

In order to figure out what size AC unit you need, you’ll need to measure the British Thermal Units (BTUs) needed for your home. Simply put, BTUs are a measurement of how much cooling power you’ll need to keep your home comfortable. There are a few different ways to complete this calculation.

Manual J Calculation

A Manual J Calculation is a complicated formula used by HVAC and energy professionals to measure BTUs for your home. While it’s not something you can do on your own, a Manual J Calculation is the most accurate way to size your AC unit because it takes every factor into account, including:

  • Square footage
  • Number of residents
  • Regional climate
  • Sun exposure
  • Number and style of windows
  • Ductwork condition
  • Insulation quality
  • Heat-generating appliances

All of these factors and more determine the amount of heat that your home produces, which affects the required size of your AC unit. With a Manual J Calculation, you can rest easy knowing that your AC system will provide the most accurate cooling power for your home.

Online BTU Calculator

If you’re determined to size your AC unit on your own or would just like to have a number in mind before speaking to a professional, there are online BTU calculators available to guide you through the calculations. Depending on which site you use, the calculation may include many of the factors listed above from the Manual J Calculation.

Simple Estimate

The easiest — and simplest — way to calculate your AC size is through a simple formula that relies only on your home’s square footage and the number of BTUs per square foot in an average home. Simply multiply your home’s square footage by 25 BTUs. While you shouldn’t base your AC purchase on this calculation, it is a good estimate to help narrow down your search.

Choosing An AC Unit

Once you’ve calculated your home’s BTUs, it’s time to choose an AC. In the unit specifications, the size will be listed in either BTUs or tons — one ton is equal to 12,000 BTUs. If your BTUs don’t exactly match the range of AC sizes, round up to the next biggest size to ensure adequate cooling.

While it’s tempting to go for a bigger unit, bigger isn’t better in the world of heating and cooling. If your AC is too big for your home, it will cycle frequently and wear out too quickly, resulting in early replacement. Likewise, if your AC is too small, it won’t be able to keep up with your home’s energy demands and you’ll never be satisfied with its performance.

Rely On HVAC Professionals

Choosing a new AC is complicated, which is why you should never go in alone. The experts at Air Tech of Pasadena will take care of all of the requirements for your home so you can focus on what you want out of your AC rather than the complex details.

Contact us today to schedule your first appointment with one of our licensed professionals.

Why Choose Us?

Pasadena’s Reliable Air Conditioning and Heating Company

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Peace Of Mind Guarantee
All technicians in your home have an extensive background check performed and are randomly drug tested for your safety.
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30% Utility Savings Guarantee
You will save a minimum of 30% on your heating and cooling costs or we will refund double-the-difference of your savings not realized during the first year.
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100% Money Back Guarantee
We guarantee that the system(s) we have installed in your home will heat or cool your home as we have stated.

What Our Customers Have To Say

Service Is the Best!

As always, service is the best! From responding to a call on a Sunday afternoon to returning the following day as early as possible to repair the issue. Professional service done on a timely manner. Deeply appreciate having AC working! Thank you!

Elvia M.

Quality Company

Daniel from Miles was fantastic. I’m so happy with my Miles AC unit and the continued service. I have peace of mind knowing my quality system is backed by a quality company. If you need HVAC work use these guys! You will not regret it.

Jeff M.

Love my Miles A/C Group

Kirk has always been very professional when he comes to our home or our business. Seems like he has been servicing us for a while now, he’s become family. I even tried to feed him a breakfast taco this morning. Love my Miles A/C Group.

Leighann G.