How to Determine the Right AC Size for Your Home

If you’re replacing an older cooling system or installing a central air conditioning unit for the first time, you might wonder: How do I know what size AC my home needs?


At Town Oil, we believe homeowners deserve clear, honest guidance when making decisions about their HVAC systems. One of the most common misconceptions we encounter is that bigger is always better when it comes to air conditioning installation. In fact, improperly sized systems—whether too large or too small—can lead to inefficient cooling, higher energy bills, and a shorter system lifespan.


So what does “AC size” really mean, and how do we help you choose the right one? Let’s walk through it together.


What Does AC Size Really Mean?


AC size doesn’t refer to the physical dimensions of the HVAC unit—it refers to the system’s cooling capacity, measured in tons. One ton of cooling equals the ability to remove 12,000 BTUs (British Thermal Units) of heat per hour from your home. Residential systems typically range from 1.5 to 5 tons, depending on the home’s cooling needs.


Choosing the right size isn’t about picking a number off a chart. It’s about calculating the cooling load—the amount of heat your system needs to remove to keep your home comfortable.


Why Sizing Your Air Conditioner Correctly Matters


Proper air conditioner sizing is essential for several reasons:


  • Comfort: An undersized unit will struggle to cool your home, while an oversized unit may cool too quickly without removing enough humidity, leaving the air clammy and uncomfortable.
  • Efficiency: Right-sized systems operate at peak performance, which reduces energy costs and saves you money on your utility bills.
  • Longevity: Air conditioning systems that are too small or too large often cycle on and off too frequently, leading to unnecessary wear and tear, more HVAC repair issues, and a shorter lifespan.
  • Air Quality: When air conditioning systems don’t run long enough to dehumidify properly, indoor air quality can suffer—especially in New England’s muggy summer months.


Don’t Rely on Online Air Conditioning Installation Calculators


We understand the appeal of online calculators or quick estimates over the phone from an HVAC company. They promise fast answers and instant quotes, often based on nothing more than your home’s square footage. But here’s the truth: sizing your air conditioning installation based on square footage alone is simply not accurate.


Think of it this way: two 2,000-square-foot homes can have completely different cooling needs based on how they’re built, how they’re insulated, and even how much sun they get during the day. And online tools—while tempting—don’t account for the dozens of real-world variables that affect your home’s cooling load.


At Town Oil, we’ve helped customers across Wethersfield, Glastonbury, West Hartford, and beyond find the right air conditioner—not the biggest or most expensive HVAC replacement. We take the time to evaluate your home and recommend solutions that make sense for your space, your budget, and your comfort.


Our Qualified HVAC Contractors Properly Size Your New Cooling System


Determining the right HVAC installation size isn’t guesswork—it’s a detailed process that experienced HVAC professionals follow carefully. That’s why it’s so important to work with a qualified, licensed contractor who takes the time to perform a cooling load calculation, which is the industry-standard method for assessing your home’s unique cooling needs.


At Town Oil, we never rush this part. It’s one of the most critical steps if you want reliable, efficient comfort for years to come—whether you’re installing an air conditioner, heat pump, or ductless mini split. We believe in educating you along the way—not pushing for the highest ticket item or making decisions based on assumptions.


Key Factors We Consider When Sizing Your AC

When we assess your home for a new AC installation, we look at far more than just square footage. Our team considers a wide range of factors that directly impact your cooling needs:


1. Insulation Quality


Well-insulated homes retain cool air better, which can reduce your system’s workload. Older homes with little or no insulation may require a larger new HVAC system to maintain comfort.


2. Window Size, Type, and Orientation


Windows can significantly affect heat gain. Large south-facing windows may let in more sunlight and heat, especially if they’re single-pane or unshaded.


3. Ceiling Height


Higher ceilings mean more air volume to cool. A 2,000-square-foot home with 10-foot ceilings requires more cooling than one with 8-foot ceilings.


4. Air Leakage


Drafty homes allow cool air to escape and hot air to enter, increasing the cooling load. We consider the condition of doors, windows, and ductwork during our assessment.


5. Number of Occupants


People generate heat, so the number of people living in the home matters when determining your cooling needs.


6. Heat-Generating Appliances


Ovens, computers, lighting, and even home office equipment can contribute to the heat load inside your home.


7. Home Layout and Duct Design


Open floor plans cool differently than homes with many closed-off rooms. Proper duct design and airflow distribution are critical to even, efficient cooling.


8. Shading and Landscaping


Trees, awnings, and other natural shading features can reduce solar heat gain and impact how hard air conditioning systems have to work.


Transparency, Not Guesswork


We’ve been serving Connecticut families since 1963, and one thing hasn’t changed: our commitment to honest, transparent HVAC services. When you work with Town Oil, you won’t get a one-size-fits-all approach. You’ll get expert guidance, clear communication, and an air conditioning installation recommendation tailored specifically to your home.


We carry HVAC products from trusted brands like American Standard and Heil, all backed by professional installation and ongoing maintenance from our skilled technicians, plus reliable AC repair if you ever need it. If you live in the Central Connecticut area, we’re just a call away when you need a trusted HVAC partner for all things heating and cooling.


Upgrade Home Comfort Without the Confusion


Choosing the right AC system doesn’t have to be stressful when you’re planning a new installation. Town Oil helps you make informed decisions without pressure, games, or guesswork. A properly sized air conditioning installation means better comfort, better energy efficiency, and better peace of mind.


If you're considering a new air conditioner this season, let our team help you get it right from the start. We’ll walk you through your options in plain language and help you find the perfect new system for your home and budget (and financing options are available, too!).


Ready to Get Started?


Call Town Oil today to schedule your in-home consultation. Our friendly, local team will evaluate your home, explain your options, and help you make a decision you can feel good about—for this summer and many more to come.