Keeping Cool: How to Choose the Right A/C Unit

By Jae Curtis

Updated March 11, 2022

Let’s be honest: when it comes to buying things for your home, your air conditioning unit isn’t the most exciting. Still, in the heat of the summer, there isn’t a component of your home that matters more. Knowing how to choose the right A/C unit could mean the difference between total comfort and a sticky, hot few months. Learn how to select yours based on size and output so your rooms and home stay cool and comfortable. Understanding a little more about how to choose the right A/C unit and how they’re rated can help you find the one that makes sense for your space. Here’s how.

Fans are only so effective at cooling your entire home. Image: Shutterstock/zstock

Types of air conditioners

First thing’s first: When shopping for an A/C unit, you need to decide which kind is right for your home. Air conditioning units come in different shapes and sizes — and prices. Consider these types so you can choose the right A/C system for you.

Central units. Central air means A/C that is pumped from one unit into your entire home through ductwork. It’s usually the most expensive type of A/C, but you’ll probably save money in energy efficiency. It’s most common in newer homes and keeps your entire house cool and comfortable.

Window units. If you don’t have central A/C (hello, apartment-dwellers), a window unit might be your best bet. It sits in your window and pumps cool air in as it pumps hot air outside. Window units are much less expensive to purchase than outfitting your home with central air, but they aren’t always as efficient. Still, they’re a great option to keep singular rooms cool.

Portable units. Can’t commit? A portable unit is easy to take from room to room. It usually requires a duct that pumps hot air outside, but the duct can be placed in a nearby window and the unit itself can be moved from room to room. They aren’t as efficient as other A/C units, but they are a great choice if you have limited space, or don’t need to cool an entire house. They’re also pretty sleek-looking, so they aren’t as disruptive to your decor as a bulky window unit.

Choose the right A/C size

One of the most important factors in knowing how to choose the right A/C is picking the right size. We don’t mean physical size, but the output for your home. Air conditioners are sized by the ton, and the general rule of thumb is to add one ton for every 600 square feet of your home. That means that if your home is 3,000 square feet and you want to cool the entire space, you’ll need a 5-ton air conditioner unit. Only need to cool a room? Figure out the size of the room and choose a window or portable unit that’s the right size based on tons. You can also consult an HVAC professional to get expert advice on the right size A/C unit for your home.

Well-maintained A/C units will work better, longer. Image: Shutterstock/Christian Delbert

Energy efficiency

Once you’ve decided on the size of the A/C unit you need, it’s time to consider energy efficiency. The U.S. Department of Energy gives every air conditioner unit a SEER rating. That stands for Season Energy Efficiency Rating. Older, less-efficient units might have lower ratings, but any A/C unit manufactured after 2006 must have a SEER rating of at least 13. If you want to save energy and costs, you can find units with SEER ratings of between 15 and 17, which are considered very efficient. Energy efficiency may seem like no big deal, especially when you can get lower-rated units for cheap. Choosing a more efficient unit, however, can definitely save you money in the long run on your monthly bills and your impact on the environment. What’s more, you could qualify for tax credits if you invest in a super-efficient central unit, which helps to offset the costs.

A/C features

It might seem like all A/C units are created equally, but looks can be deceiving. Newer air conditioners come with tons of cool features that can save you money and make cooling your home more convenient. Check out some of the newer features, such as:

Smart thermostats. When an A/C comes with or is compatible with a smart thermostat, you stand to save money. Smart thermostats can learn about your habits and cool your home more efficiently by only cooling when you’re home or automatically setting to the right temperature. You can even control many smart thermostats from your phone. That way you don’t have to wait until you’re home to kick on the A/C.

Fan only options. In some cases, a fan might be enough to help your home stay comfortable. Look for an A/C that offers other options and you can keep your energy bills low.

Auto delay switch. There is cool air trapped in your air conditioner when you switch it off. In older models, that cool air simply dissipates. Newer models have an auto delay switch, however, that pushes out the last of the cool air once you’ve shut the unit off. This means no cool air goes to waste and you save money on your energy bill.

New York brownstones with window air conditioners

Window units are ideal for apartment dwellers. Image: Shutterstock/rSnapshotPhotos

Understanding warranties

Before you purchase a new A/C unit, make sure you understand the warranty that comes with it. Most new units have some type of warranty, but they’re definitely not created equally. Not only do the warranty lengths differ from brand to brand (one year versus five years, for example), but what the warranty covers differs as well. Some will cover parts and labor if your unit malfunctions, while others only cover certain parts in the unit, like the pump or the condenser. Warranties for central air are usually more extensive than a warranty for a portable or window unit. Make sure you read the fine print before you purchase a new A/C unit so there won’t be any surprises down the road.

Still have questions? Talk to an expert

Your air conditioner is one of the most important components of your home. Unfortunately, you never really think about it until it gets too hot or it stops working. By knowing how to choose the right A/C unit, you can keep your home cool and save money on your energy bills. As always, it’s a great idea to consult a professional before you make a big purchase like an A/C unit. Keep comfortable all summer long so you have time to focus on the other parts of your home.