What Size Central Air Conditioner Should I Buy?

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What Size Central Air Conditioner Should I Buy?

When you’re buying a new car battery, you don’t just grab the first one you see off the shelf at the automotive store; you look up the specific battery that fits with your car or ask an auto expert at the store. That’s because you know that although your car might run with the wrong size battery, it won’t run well. The wrong battery could damage your alternator, result in a breakdown and ultimately put a lot of unnecessary strain on your car. The same thing goes for installing the wrong size central air conditioner in your home.


When you’re shopping for a new central air conditioner, it’s critical you choose a unit that’s sized appropriately for your home. If you install the wrong size, your air conditioner could struggle to maintain comfortable temperatures and humidity levels or even breakdown. If you’re in the market for a new HVAC, Dallas, TX, professionals at Dial One Johnson Plumbing, Cooling & Heating can help you pick out the most appropriate unit for your home. Keep reading to learn why the size of your air conditioner matters, how it affects your home and how to choose the best system for your needs.


In addition to helping you select and install a new central air conditioner, the HVAC professionals at Dial One Johnson can provide the air conditioning repair service necessary to maximize your system’s lifespan. Contact us online to schedule service.  

Why Air Conditioner Size Matters

If you’re in a hurry to replace your central air conditioner, you may be tempted to skip the calculations and just choose one that you know has a lot of power. Afterall, what’s the big deal if the air conditioner’s made for a larger space? Won’t it just cool the house even faster than a correctly sized unit? Unfortunately, that’s not how it works.

Wasted Money

One of the reasons it’s important to buy a correctly sized air conditioner is to avoid paying more money for no reason. The larger the air conditioning unit is, the more expensive it is, both to buy and install. Additionally, an oversized central air conditioner is prone to short-cycling, which can drive up utility bills and decrease its lifespan. Central air conditioners that are too small may run continuously to attempt to cool your home, which can also increase your utility bills.

Indoor Air Quality

In addition to cooling your home, a central air conditioner should also dehumidify it. Most air conditioners keep indoor humidity levels between 30% and 50%. However, in order to dehumidify your home, an air conditioner has to run normal-length cycles, which improperly sized systems do not do.


An oversized central air conditioner doesn’t generally run long enough to remove humidity from the air. High levels of humidity can cause many indoor air quality problems, including the following:


  • Mold and mildew growth
  • Indoor pollutants that grow in a humid environment
  • Damage to brickwork ane walls
  • Rotting furniture and floors
  • Discomfort and heat exhaustion

Durability and Lifespan

Improperly sized air conditioners just don’t run as efficiently as properly sized ones. When an air conditioner isn’t running efficiently, it has to work harder. Air conditioners that are too small will run continuously in an effort to hit the desired temperature, but they’re not built to run non-stop. Similarly, an oversized air conditioner will blast cold air and shut down quickly, which is hard on the machinery. When you buy an improperly sized air conditioner, you’re running the risk of replacing it much sooner than if you’d bought a properly sized unit.


Want to buy the best HVAC Dallas, TX, can provide? The air conditioning experts at Dial One Johnson are here to help. We’ve partnered with Lennox HVAC systems to bring you the highest-quality, most affordable systems on the market. 

What AC Size Do I Need?

To gage what size air conditioner you need, you should look up an air conditioner’s British Thermal Units (BTUS). BTUs are used to measure how much heat a particular air conditioner can remove from a space in an hour. To properly cool a space, you need about 20 BTUs per square foot.


Calculating the BTUs with square footage is an easy, straightforward way to get a ballpark idea. However, there are some additional factors to consider when making these calculations, including room characteristics, amount of sunlight and where you live. These factors can complicate matters, which is why it’s important to consult an HVAC professional.

When Should I Replace My Central AC?

Knowing when to replace your central air conditioner is just as important as knowing what size you need. Too often, people wait until their HVAC system has completely broken down before thinking about replacement. Depending on your home’s needs, your central air conditioner can take some time to replace, so waiting until the last minute can cause a lot of unnecessary discomfort for you and your family. Here are some signs that your central air conditioner is on its last legs:


  • Your air conditioner requires constant repairs
  • Your air conditioner is 15 years or older
  • Your air conditioner uses R-22 refrigerant, an older refrigerant that has been banned from production by the Environmental Protection Agency.

Dallas HVAC Professional

Before choosing a new central air conditioner, remember that size matters. The size of your central air conditioner will play a large role in determining your comfort, air quality and how much money you spend. For all-things HVAC, Dallas, TX, experts from Dial One Johnson are your best resource. They’ll help you determine which central air conditioner will work best for your home and needs.

Concerned about cost? We understand. That’s why Dial One Johnson offers multiple financing options, so you don’t have to spend a dime upfront to get the service you need. Visit us online to schedule air conditioning repair service, or give us a call at 469-557-2703.

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