If you’re shopping for a new AC system for your home in the Oklahoma City, OK area, you have multiple factors to consider. Among these are the cost of the system, its efficiency, and its quality. However, none of those things matter much if you don’t choose the right size of AC for your home.

A unit that’s too small will struggle to keep you comfortable and will wear out prematurely. One that’s too large will be inefficient and may also suffer from unnecessary wear and tear. As a result, you need to understand the factors involved in proper AC sizing before you make any purchase decisions. To help, we’ll explain six factors our technicians use when choosing a properly sized AC system for your home.

1. Understand AC Sizes

Understanding how to interpret the sizes of the AC systems is paramount. If you’re buying a traditional central ducted AC system, you will see that they measure capacity by the ton. If you’ve only ever bought window air conditioners, you’re likely used to seeing AC capacity measured in BTUs. The good news is that both units of measure express the same thing, and converting between them is easy. All you need to know is that a one-ton central AC provides 12,000 BTUs of cooling capacity.

You should also know that central ACs come in half-ton size increments. This means you’re unlikely to find an AC with the precise cooling capacity your home needs. However, the rule of thumb is to always round up. So, for example, consider a home that requires 38,000 BTUs of cooling capacity. In that case, you’d need a 3.5-ton AC system, which offers 42,000 BTUs of cooling capacity. A 3-ton unit, which offers 36,000 BTUs, would be slightly undersized for the home.

2. Consider Your Climate Region

The sizing of an air conditioner system depends on the climate in which the system will operate. Here in Oklahoma City, we’re in climate zone 1. That means we live in a hot climate with plenty of humidity. As a result, homes here have relatively high cooling demand. In this area, you will need at least 20 BTUs of cooling capacity per square foot of space in your home.

3. Consider the Size of Your Home

One of the most important elements that goes into sizing an AC system is the size of the space you need to cool. So, the first thing you should consider is the square footage of your home. That will allow you to compute a rough estimate of your home’s cooling capacity needs. Just multiply your home’s square footage by 20 to come up with a capacity estimate in BTUs. Then, divide the result by 12,000 to convert the figure to tons. The following chart includes common residential AC system sizes and the square footage they can serve.

  • 1.5 tons for 600 to 900 sq ft
  • 2 tons for 901 to 1200 sq ft
  • 2.5 tons for 1201 to 1500 sq ft
  • 3 tons for 1501 to 1800 sq ft
  • 3.5 tons for 1801 to 2100 sq ft
  • 4 tons for 2101 to 2400 sq ft
  • 5 tons for 2401 to 3000 sq ft

4. Consider Your Home’s Unique Heat Loads

Since the capacity estimate you’ll get from its square footage alone is imprecise, you must next fine-tune it. To do that, you must factor in some of your home’s unique heat load contributors. For example, the number of windows and doors your home has will affect how much cooling capacity you need. The size of the windows, which direction they face, and their insulating capacity also matter. Factor in how many people reside in your home. You’ll also need to consider the size of your kitchen and how you use it. The following is a chart of heat load factors and how many BTUs to add to your capacity estimate for each.

  • 100 BTUs for each occupant in your home
  • 1000 BTUs for each standard window
  • 1000 BTUs for each exterior door
  • 1000 BTUs for each room with ceilings above 8′
  • 1200 BTUs for a standard kitchen with moderate usage
  • 2400 BTUs for a large kitchen with high usage

5. Consider Your Home’s Insulation Quality

You will also need to factor the quality and performance of your home’s insulation into your cooling capacity estimate. This is because your home’s ability to keep hot air out and cool air in will change its cooling needs. If your home has average insulation, you can use the estimate you’ve arrived at to this point. However, if your home has poor insulation, you will need to add between 10% and 15% to your estimate. You can deduct between 10% and 15% from your estimate if your home has excellent insulation.

If your home has poor insulation, you may want to upgrade it before installing a new AC system. For one thing, it may save you money upfront because it could reduce the size of the system your home needs. Also, better insulation will improve the energy efficiency of the AC system, saving you money every month on your energy bill. Over the lifetime of your new AC, this will save you significant sums on your cooling costs. Plus, it will reduce the wear and tear on your AC, lengthening its useful lifespan.

6. Leave It to the Pros

Unfortunately, the work you’ve done up to now will only get you reasonably close to an accurate AC size estimate. You’d need to consider many more home-specific factors for maximum accuracy. You’d need to think about things like total sunlight exposure and the direction your home faces. You’d also need to evaluate the size, design, and condition of your home’s ductwork.

Fortunately, the Air Conditioning Contractors of America (ACCA) maintains a guide that spells out AC sizing factors. It’s called Manual J. This is the guide that professional HVAC installers like ours use to arrive at precise AC size estimates. It contains a formula that allows us to factor in every aspect of your home’s heat load. We perform that calculation for every home where we install an AC system to ensure it performs well.

Local AC installation Experts

For over 15 years, True Climate Heat + Air has been the HVAC company that Oklahoma City homeowners trust for AC installations. We also install heating systems, heat pumps, and ductless mini-splits. Our team of expert HVAC technicians is NATE-certified. Plus, we’re a Trane Comfort Specialist, which means we sell and install the finest AC systems on the market. We even offer financing options on approved credit to help you pay for the new AC system your home needs.

We’re happy to work on new construction, and also have a team of highly-qualified plumbers. We’re Better Business Bureau-accredited, so you can count on exceptional workmanship and customer service. So, if you need a new AC system installed in your Oklahoma City home, call our team at True Climate Heat + Air today!

company icon