How Do I Find the Tonnage of My AC Unit?

AC condensing unit with label listing specs such as tonnage.

Are you in the market for a new air conditioner? If your unit has stopped working effectively, you may be ready to replace it. Before making a purchase decision on a unit, you’ll need to determine the best size for your home. This is essential for both efficiency and savings. A unit that's too big or small will not heat or cool your home efficiently and will cost you more to operate. Therefore, finding a unit that is correctly sized for your home is essential. HVAC systems are sized according to their tonnage, which may lead you to ask how to find tonnage on an AC unit. The answer can help guide your search for a replacement system. After all, AC tonnage describes cooling capacity, which is something you’ll definitely want to understand as you shop for a new unit.

How to Find AC Unit Tonnage

Knowing where to start when searching for a replacement air conditioner can be difficult. You may find yourself asking what size AC unit you need. You may find the answer on your current unit. Find your condensing unit and search for a data plaque or sticker on the side. You should see a model number and a string of numerals and letters. There should also be an even, two-digit number – which indicates the AC tonnage of the unit. This number is typically between 18 and 60. Divide this number by 12 (representing 12,000 BTU/hr, or one ton of cooling capacity) to get the overall tonnage of the unit. This chart may also be useful when converting the numbers:

  • 18 = 1.5 tons
  • 24 = 2 tons
  • 30 = 2.5 tons
  • 36 = 3 tons
  • 42 = 3.5 tons
  • 48 = 4 tons
  • 60 = 5 tons

What is AC Unit Tonnage?

Heating and cooling capacities are measured using British thermal units (Btu) per hour. One Btu equals the heat generated by a single candle. It’s the amount of heat required to raise the temperature of one pound of water by one degree.

AC unit tonnage describes the cooling capacity of your air conditioner. One ton of cooling is the rate of heat transfer required to freeze 2,000 lbs – or one ton – of water over the course of 24 hours. This equals 12,000 Btu per hour.

Why is AC Unit Tonnage Important?

When it comes to sizing AC units, more tonnage is not necessarily better. While you might be tempted to invest in the biggest unit available, this may overwhelm your space, raise your energy costs, and decrease energy efficiency. Short cycling often leads to increased wear and tear, causing a shorter overall lifespan for the unit. Short cycling also prevents dehumidification, leaving your space cool but clammy. Turning the temperature down might help, but this raises your electricity usage and overall energy costs.

Bigger air conditioners cost more to purchase and operate. Of course, you don’t want to go too far in the other direction, either. Undersized units may struggle to cool your space effectively, especially on hot summer days. A system that is too small for your space will run more frequently, causing more wear and tear and increased repairs. So finding the optimal size unit for your space is the key to energy efficiency and performance.

What Size AC Unit Do I Need?

You’ve answered the question: how to find tonnage on an AC unit. Now what? Tonnage is just one factor to keep in mind as you shop for a replacement. Your new unit shouldn’t necessarily have the same tonnage. If you’ve made improvements to your space since you last installed your air conditioner, you may not need as powerful a unit. Conversely, if you’ve added onto your home and increased your square footage, you may need more cooling power. It’s also possible that your existing unit was never properly sized for your space to begin with, and therefore, you’ll need to adjust the size of the new unit accordingly.

While AC unit tonnage can be helpful to know, it’s important to keep other features in mind. There are three main types of air conditioners, all of which cool using similar methods. Before shopping for a replacement, consider how you like your existing system. Whether you have a ductless AC, packaged air conditioner, or split-system air conditioner, you’ll want to maximize your comfort and system efficiency with your next upgrade.

Factors Beyond Square Footage

While square footage is an important factor to keep in mind when replacing your air conditioner, it’s far from the only consideration. If your home is especially shaded or receives a lot of sun, you may need less or more AC unit tonnage. The number of occupants also impacts your unit’s ability to cool your space. The location also plays a role – if you’re mounting your air conditioner near the corner of a room, you’ll want a unit that sends airflow in the right direction.

It’s easy to feel overwhelmed by the possibilities. Your local Aire Serv professionals are happy to walk through the options with you and help you understand how to read the tonnage of an AC unit.

Call Aire Serv® for Help Sizing Your Air Conditioner

If you’re confused about what tonnage AC you need, allow Aire Serv® to help you figure it all out. Our team of professionals can help you find the correct size for your space and guide you through a number of high-quality options. If efficiency is a top priority, we can review some cost-effective solutions when upgrading your system. Once you decide on a particular unit, we’ll install it to ensure maximum performance. Trust Aire Serv to help you through every step of your AC upgrade – schedule your appointment online today or call us!