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SEER and AFUE Ratings: What Do They Mean for Your HVAC System?

You have much to consider when buying a new HVAC system for your home in Menifee, CA. When you start researching furnaces and air conditioners, knowing the difference between SEER and AFUE ratings helps you make an informed purchase. Here’s what you need to know about the two ratings:

Seasonal Energy Efficiency Ratio

Firstly, SEER is an acronym for Seasonal Energy Efficiency Ratio, and it measures the total cooling power of heat pumps and central air conditioning systems throughout an average cooling season. The rating gives you an idea of the efficiency of your cooling system. The higher the rating, the more efficient the system and the less energy it uses. Thirteen is the minimum industry rating. Yet, industry professionals recommend purchasing a new system with a rating of 15 or higher for maximum efficiency.

AFUE Rating

Annual Fuel Utilization Efficiency (AFUE) gives you a good idea of how much fuel a furnace uses that actually converts to heat. AFUE ratings get expressed as percentages. The higher the percentage, the better. Natural gas furnaces have a standard AFUE efficiency rating between 78%-84%; whereas a condensing furnace has an AFUE between 90%-97%.

The Differences Between the Ratings

Finally, when shopping for a new heating or cooling unit, you want to have a firm grasp on the differences between the two ratings. Fortunately, they’re fairly straightforward. Here’s a quick cheat sheet to help you remember the differences:


  • Measures cooling efficiency.
  • Compares BTUs with watt-hours.
  • Minimum industry standard is a rating of 13.


  • Measures heating efficiency.
  • Compares BTUs with BTUs.
  • Condensing furnaces offer the highest ratings between 90%-97%.

Purchasing a new furnace or air conditioner isn’t something you do every day. With ever-changing technology, it’s not always the best choice to swap your existing system for an upgraded version of the same type. You have more choices than you realize. You want to make sure the choice you make is something that performs well for you for the next 15-25 years.

For all questions about HVAC replacement, including SEER and AFUE ratings, call the team at Castillo Heating & Air Conditioning, Inc. for expert guidance. By doing so, you’ll take a significant step toward enhancing your home comfort for the lowest price possible.

Image provided by iStock

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