Buying Guide: Central Air Conditioners

Purchasing or replacing central air for your home? It can be a big decision. Here’s everything you need to know to purchase the most efficient unit.

In the heat of the summer, it might seem that any central air conditioner will do just fine, but it’s important to do your research so you can choose the right unit and ensure the best performance for your home.

In fact, electricity bills rise in the summer because of air conditioning. Over the course of the summer, an AC can account for up to 30 per cent of the season’s electricity bill. That’s a lot of cooling, and a lot of energy. So here’s what to look for before you purchase to help you stay cool and save this summer.


Is central air right or your home?

If you’re looking for a full-home cooling system, central air is the right choice. These systems take up no space indoors and are long lasting. The average lifespan of a unit is 15 to 20 years. It’s important to keep in mind that these units are on the higher end of the cooling equipment spectrum. They require professional installation and could require the installation of duct work, depending on your home.



Only looking to cool one or two rooms?

A room AC might be right for you. Read our room air conditioner buying guide to learn which model is right for your home.


Work with a local HVAC contractor


The installation of a central AC is key to its performance. Working with a reputable air conditioning contractor can help ensure that the installation is completed properly.

A contractor can also help answer any question you may have and recommend best options for your home, including the correct size and most efficient models.

Before choosing a contractor, don’t be afraid to shop around. Ask for quotes and letters of recommendation from past customers so that you can choose the right contractor for the job.

Choosing the right size


Size is an important factor to consider when purchasing a new central AC. If a unit is too small, it may not be able to keep up on especially hot summer days; if it’s too large, it could cycle on and off frequently, leading to poor air dehumidification, decreased home comfort and higher energy costs.

Although your contractor can help you with choosing the proper size, an easy way to get an idea of what you’ll require is by determining the cooling capacity needed of the space you’d like to cool. Cooling capacity is indicated by British thermal units (BTUs/hour). The chart below shows the BTUs needed based on square footage.



Area to be cooled (square feet) Capacity needed (BTUs/hour)
700 up to 1,000 18,000
1,000 up to 1,200 21,000
1,200 up to 1,400 23,000
1,400 up to 1,500 24,000
1,500 up to 2,000 30,000
2,000 up to 2,500 34,000

Which model is right?


Once you’ve determined what size is best for your home, you’re ready to start thinking about which model is right for your needs. When shopping around, make sure to make energy efficiency a part of your wish list.

There are a few ways you can identify energy-efficient models; first look for the blue ENERGY STAR® label. ENERGY STAR® designation helps you identify systems that provide the best performance while using the least amount of energy. On average, these models use eight to ten per cent less energy than other standard models.

Each unit will also have an ENERGUIDE label. This label includes the model type and its Seasonal Energy Efficiency Ratio (SEER) which refers to the unit’s cooling efficiency over the entire cooling season. The label includes a SEER scale to show the range available for similar models, and an indicator that shows where the model falls on the SEER scale.

The SEER for central AC units range from 10.0 to 17.0. Depending on the system type that you get, ENERGY STAR units must meet a SEER of 12 or greater.

There are also other energy-efficiency features you can look for, including:


  • Large coils: larger coils allow for more efficient heat transfer and are often quieter.
  • Fan-only switch: Accessible from your thermostat, this feature allows you to turn off the unit’s cooling but leave the fan on to circulate air.
  • Automatic delay fan switch: This fan switch feature keeps the fan on so that even if the unit’s compressor is off, it can still utilize the left over cool air. Like the fan-only switch this feature is accessible from your thermostat.
  • Filter indicator light: This feature let’s you know when the filter requires changing. A well maintained AC will work more efficiently. Make sure to have it serviced yearly.

TIP: If you have a smart thermostat, make sure it is compatible with your new central AC unit before purchasing.


Remember, before making this purchase it’s always best to connect with a reputable contractor to ensure you have made the best decision for your home. Make sure to consider your needs, and what features are best suited to achieve them, so once summer rolls around you’ll be staying cool comfortably and efficiently.

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