What Size Central AC Do I Need? A Michigan Tech Answers

In the market for a new AC system?

If so, you might be wondering what size system you need.

Here’s the thing: Without us looking at the specifics of your home, we can’t give you an accurate estimate.

The only way to know exactly what size AC you need is to have a Replacement Specialist perform a cooling load calculation. This calculation takes into account several factors specific to your home to determine what size AC you need.

To help you understand AC size better, we’ll cover the following info in this article:

1. How AC size is measured
2. Why you need the correct AC size
3. Why a professional needs to help you calculate AC size

Want a pro to help you find the right size AC system for your home?

Air conditioners are sized according to their BTU (British Thermal Unit) output, which is a measurement of how much heat an AC can remove from your home in one hour.

Most residential air conditioners range anywhere from 18,000 to 60,000 BTUs. You’ll also see AC size measured in tons, which uses smaller numbers to express a unit’s BTU output.

Below is a chart to help you compare BTUs with tons:

• 1 ton = 12,000 BTUs
• 1.5 tons = 18,000 BTUs
• 2 tons = 24,000 BTUs
• 2.5 tons = 30,000 BTUs
• 3 tons = 36,000 BTUs
• 3.5 tons = 42,000 BTUs
• 4 tons = 48,000 BTUs
• 4.5 tons = 54,000 BTUs
• 5 tons = 60,000 BTUs

Here’s the skinny: Installing an incorrectly-sized air conditioner will lead to trouble down the road.

• If your AC is too small, your AC will run constantly in an attempt to cool your home. As a consequence, you’ll have higher energy bills and your home will struggle to reach your desired temperature.

• If your AC is too big, your AC will cool your home really fast and then shut off quickly. While that might not sound like an issue, the frequent “start-stop” causes extra wear and tear on your AC system, which can lead to expensive repairs and/or breakdowns. Additionally, you’ll have more hot and cold spots around your home, which can cause discomfort.

Sizing an air conditioner correctly involves calculating many factors specific to your home (this is called a cooling load calculation).

A cooling load calculation takes into account factors such as:

• The square footage of your home
• Your home’s geographical location
• The insulation levels of your home
• Height of ceilings
• Number of doors and windows
• Type of roof
• Orientation of your home (i.e., north-facing, east-facing, etc.)
• And much more

Since these factors can be very complex to measure and calculate, only a professional with the right tools can accurately determine the right size AC for you.

Note of caution: As you can see in the list above, a proper load calculation takes into account much more than square footage alone. If a technician tries to recommend a size by only looking at the square footage of your home, do not hire them to install your new AC. General estimates based solely on square footage are not accurate, which means you’ll likely end up with a system that’s too big or too small for your home.

All of our AC Replacement Specialists are trained to perform accurate cooling load calculations. When you hire us to install your new air conditioner, you can rest assured you’re getting the right size system for your home.