If you’re in the market for an AC unit for the first time, it can be a bit overwhelming to sift through all of your seemingly endless options. Having a better understanding of one of the most important factors in selecting a new air conditioner will help you narrow down your search and ensure you choose the right AC for your home. Let’s go over what AC size means and how to figure out what size AC you need.
What is AC size?
When comparing air conditioner sizes, we’re not comparing the physical size of the unit but the size of space it can cool. This is called the cooling capacity, and it’s often represented by tonnage (1 ton, 1.5 ton, etc.) or British Thermal Units per Hour (BTUh). These measurements tell us what the air conditioner’s cooling capacity is over an hour, which tells you as a potential buyer whether an AC unit is powerful enough to cool your home properly.
BTUh vs. BTU
If you’ve already done a bit of research, you may be wondering, “What is BTU then?” When searching online, you’ll see a lot of information about BTUs but not BTUh. It’s important to understand that BTUh and BTU mean different things but are often used synonymously. You’ll more commonly find AC size measurements referred to using BTU than BTUh.
How to Calculate AC Size
Determining the best AC size for your home is about much more than how big your house is. Your HVAC company will conduct a load calculation called the Manual J calculation to determine your home’s ideal AC size based on a wide variety of factors. These include:
- Square footage
- Number of residents
- Insulation quality
- Climate and weather conditions
- Amount and type of windows and doors
- Amount of sun exposure
- Type of siding
- Ductwork condition
- The number of heat-generating appliances (stove, dishwasher, etc.)
If you haven’t found a company for your AC installation yet but want to explore some AC options, you can get a rough estimate of the proper AC size using an online BTU calculator, which guides you through the long, complicated process of a Manual J calculation. However, it’s important to keep in mind that these calculators are prone to inaccuracy, and a licensed HVAC technician is the best person for the job.
Bigger Doesn’t Mean Better
It can be tempting to go for a bigger AC unit than necessary because logic typically tells us bigger is better. However, a bigger air conditioner won’t have enough space to cool, resulting in short, frequent cycling and too much wear on the system over a short period of time. Getting an air conditioner that’s too big will result in an early replacement.
Similarly, an AC that’s too small will never be able to provide adequate cooling to keep you comfortable, and it will have to work much harder to keep up with your cooling needs. This will also result in undue stress on the system. When it comes to your new AC, choose a unit that is properly sized for your home.