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What Do the Efficiency Ratings on an AC Mean?

ENERGY-STARThe simple answer to this question: The efficiency ratings found on air conditioning systems indicate how well the unit converts its electrical power into cooling output. The higher the rating number, the less energy goes to waste—and, usually, the less it costs to run.

You may have figured out this much on your own. What you really want to know is what the specific efficiency ratings mean for air conditioners: EER and SEER. This is also basic to understand without bringing in the hard math. However, as we’ll explain later, you’ll still require the assistance of an air conditioning service company in Raleigh, NC when the time comes to pick a new unit to install. An efficient air conditioning system that’s not the right fit for a home, or which was installed poorly, will end up wasting energy anyway.

The Meaning of EER and SEER

These two efficiency ratings are similar. The difference between them is how they are tested.

  • EER (Energy Efficiency Rating) – This is a ratio of the output of cooling to the input of electricity. Output is measured in BTUs (British Thermal Units) removed from the air, and input is measured in watt hours. To determine EER, technicians run the unit under specific conditions of temperature and humidity. Usually the test lasts for an hour.
  • SEER (Seasonal Energy Efficiency Rating) – The ratio for SEER is identical to EER. What’s different is that SEER is tested over an entire season of cooling, rather than a single test with set conditions. SEER therefore gives a consumer a better understanding of general performance. SEER is almost always higher than EER.

Common Efficiency Ratings

What is a good SEER/EER rating for an air conditioning system? ACs come in a range of efficiencies, but in order to meet the minimum for the EPA’s ENERGY STAR program, a split system central air conditioner must have a SEER/EER of 15/12.5 or higher. A unit with this rating is considered a mid-efficiency system—it’s good, but could be much better.

Thanks to advances in HVAC technology such as variable-speed fans, multi-stage compressors, refrigerant blends, and thinner metal condenser coils, many air conditioning systems can obtain SEER ratings higher than 20. This can make a significant difference in home utility bills over the year. High-efficiency systems cost more than mid-efficiency ones, but their savings often make up for it.

Don’t Go It Alone With Choosing a New AC

We have a special caveat about air conditioning efficiencies: don’t purchase a new AC just because it has high SEER/EER. A high rating may look tempting, but it doesn’t automatically guarantee savings. Picking the wrong type and size of air conditioner means an air conditioner that won’t work correctly and will waste power. The most efficient air conditioning system ever manufactured may still end up running constantly and sucking away energy if it isn’t the right size for a home.

When you’re hunting for a new air conditioning system, work with our professionals so you end up with the ideal AC—both for comfort and energy savings.

Comfort Master Heating & Air Conditioning, Inc. offer service throughout the Triangle Area of North Carolina. Schedule an appointment for AC replacement today.

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