SEER VS SEER2 What’s the Difference?

One of the main issues – or so it can seem like – with getting a new AC or cooling system is picking one out. There are many different features and functions you need to consider, and even something like picking a single system can be difficult. Once all that’s out of the way and you’ve picked out a system for your home, you might find something called a SEER 2 rating on it.

Some homeowners might not find it important, but what does the SEER 2 rating mean for those that do? You might have even heard of something called SEER and only ended up with more questions. In this article, we’ve covered exactly what SEER and SEER 2 are and what their differences are.

If you want to learn more, just contact our River Valley Air Conditioning team.

What Is SEER and What Does It Represent?

Business Credit Score Gauge Concept, Excellent Grade.

For quite some time, SEER was considered the main way of understanding how an air conditioner used its energy. Standing for Seasonal Energy Efficiency Ratio, SEER was used by HVAC technicians – and some homeowners – to understand how much cooling output a system gave during an entire summer. 

To give a specific number, the ratio recorded after a test was divided by how much energy the system used. The result was a number that could tell you how efficient the cooling system was. Higher values were a sign that the system had a good or better energy efficiency than others and soon, many federal governments made a specific SEER rating a requirement. 

Today, any older AC or other cooling systems must have a minimum rating of at least 15 SEER in Arizona.

What Is SEER 2 and What Does It Represent?

SEER 2, like SEER, stands for Seasonal Energy Efficiency Ration version 2. As the name suggests, the SEER 2 rating is another similar system though with stricter testing to better measure energy efficiency. The measurements and calculations are still the same, though; a higher rating still means higher energy efficiency.

One important thing to note when looking at a SEER 2 rating on an AC or any other cooling system is that the system is likely to be far more efficient with a higher rating. Since SEER 2 is far stricter during its testing, the tests are far more accurate. This means that a higher SEER 2 rating will be more efficient at using energy to cool your home than the same SEER rating!

The Differences in SEER vs. SEER 2

As mentioned, the main difference between SEER vs SEER 2 is the stricter testing standards and requirements. During the testing period, an HVAC technician will use a special testing method that uses external pressure to move water inside the system’s column. Measured in inches of water in the column or in. WC, the measurement shows how much pressure is needed to push the water up to a certain point. 

Both SEER and SEER 2 use the same method during testing, though the stricter rate of testing makes each different. The SEER 2 version of the test typically focuses on moving the water up 0.5 inches in the column, while SEER only aims for 0.1 inches. 

Ultimately, if the cooling system being tested can move the water up 0.5 inches without using too much energy – or something similar in other tests – then the SEER 2 rating will come out high. At the end of the testing, SEER testing will seem to be more energy efficient due to how the standards used are lower. The SEER 2 rating is more accurate due to having a stricter and higher bar to calculate.

Is SEER Still in Use?

In some states, there’s a chance that you’ll see an AC or heat pump with a SEER rating still on it. Though the United States and Canada have switched to SEER 2 as of January 2023, cooling systems with a SEER rating can still be installed. These systems are often at least a 14 SEER, though, which makes them quite an energy efficient even if SEER 2 systems are far better.

However, these 14 SEER units must be manufactured and built before January mentioned if they’re being installed into a home. Any new cooling system must comply with the SEER 2 rating and be at least 14.3 SEER 2. If you do find a cooling system with a SEER rating, it needs to be a rating of 15.

SEER and SEER 2 Calculations and Equivalents


While SEER is rarer today, knowing how energy efficient your current AC or heat pump is can be quite useful for a homeowner. As we mentioned, the two ratings are identical, though SEER 2 is far more accurate. If you’ve recently moved into a new home with a SEER-rated AC and want to upgrade sometime this year, calculating the SEER 2 rating can help you choose whether you want a more energy-efficient model.

Simply put, the numerical difference between SEER and SEER 2 is about 4.5%, with SEER being higher. So, if you have a 14 SEER air conditioner, the same system would have a 13.4 SEER 2 rating when converted. Similarly, a 15 SEER rating would become a 14.3 SEER 2, and a 14.5 SEER converts to a 13.8 SEER2. 

In the case that you get a new cooling system that still has a SEER rating installed this year, converting the rating is vital. Arizona requires newly installed systems to have at least a 14.3 SEER 2 rating. If your current system is below that in either rating system, it can be a sign you need to upgrade soon.


SEER and SEER 2 are special ratings that can help both homeowners and HVAC technicians determine how efficiently a home’s air conditioner or heat pump uses its energy. Having recently started being used at the beginning of 2023, SEER 2 replaced SEER as a far more accurate system. The stricter testing for SEER 2 allows homeowners to know that their cooling system is highly energy efficient and can even help guide new purchases. 

If you want to learn more about SEER and SEER 2 ratings and want to install a new system, call our team at River Valley Air Conditioning.