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When shopping for a new AC, you can make a more educated decision when you understand the definition of SEER. You also need to ask for the AHRI certificate and then match up the components listed on it, to the ones that are going into your home. Verify that you are getting the exact equipment on the AHRI certificate.

The Details

When it comes to most consumer goods, they show up to you, ready to go. That washing machine that you just bought, only requires a few hoses and a power cord before it starts working for you. However, when it comes to your homes HVAC system, each one is a custom installation. A custom installation whose final configuration is nearly infinite in the number of possible combinations.

Configuration Possibilities

For example, does your home have natural gas or propane?

If you do have gas heat, then we need to select a furnace for you, based on winter time heating requirements and also summertime airflow requirements. Because, not only does the furnace heat the air in the winter time, it also moves the air throughout your homes duct system year round, regardless of whether you are heating or cooling.

If you do not have gas heat, then we need to size your air handler for both the AC system and the available electrical circuit for the heat strip. Or, maybe, we can go with a heat pump to save a little on your electric bill in the winter-time (more on heat pumps in a later article).

Then we need to choose an outdoor AC unit and match it with the proper indoor coil, that also best matches with the air handler or furnace.

As you can imagine, how much energy the whole combination consumes when heating and cooling your home can vary a lot, and this is where AHRI comes in.

What is AHRI?

AHRI, as far as we are concerned in this article, is an independent third party that puts all of the combinations together in a laboratory, and accurately measures how efficient the combination is.

What do you really have?

“Now Anthony, I was told that I have a 16 SEER AC system… Look, see, the shiny label on my AC unit outside says LENNOX CARRIER TRANE 16 PRESTIGE… The 16 means 16 SEER!”

Well, maybe.

That badge was placed there by the marketing department at the AC manufacturer. What it means is that in SOME configurations, 16 SEER is possible. In most configurations, however, it is probably 14.5 SEER to 15.5 SEER

The thing to take away from this portion is that when you are shopping for a new HVAC system, ask the installing contractor to see the AHRI certificate, and then match up the components listed on it to the ones that are going into your home. I see it all the time, where homeowners were sold the warm fuzzy feeling of a 16 SEER system, due to the shiny badge on the unit outside, just to find out that they do not really have a matched system.

“Okay Anthony, I got it… That makes sense… However, what does this SEER business mean?” What is the definition of SEER?

SEER Simplified

Basically, it is a ratio of cooling received over energy used. For example, 16 SEER can also be written as 16/1, which ultimately means that for every 1 unit of energy used, you receive 16 units of cooling. In reality, however, it is a little more complicated than that BUT – for the purposes of this article – this explanation will do just fine (if you are curious to know more, please feel free to call me and I will gladly explain the finer details).

“Okay Anthony, what does that mean for me when it comes to the bottom line?” 

Well, 15 SEER to 16 SEER is where the sweet spot is for 99% of homes out there. Unless you have the upgraded duct work and insulation to go with it, anything more efficient is a waste. Even a basic 14 SEER system is perfectly acceptable if a 15 SEER to 16 SEER system isn’t possible. In fact, I would rather have a new 14 SEER system with brand new duct work, over an 18 plus SEER system.


So, the moral of the story is: When shopping for a new AC system, ask for the AHRI certificate and also do not overspend on high SEER numbers, thinking that you will get it all back in 2 years from electric savings. Understanding the definition of SEER and also understanding how AHRI rates HVAC systems, will put you ahead of the game.

If you have any questions, please feel free to contact me – Anthony – at 33 Solutions LLC!