Three HVAC Terms You Should Know When Dealing with Your System

Three HVAC system terms that are useful to know include AFUE, SEER and HSPF. These describe the energy efficiency of central heating and cooling systems. The U.S. Department of Energy (DOE) requires that some heating equipment and all air conditioners carry ratings that help consumers make decisions about the systems they choose for their homes. 


Short for annual fuel utilization efficiency, the AFUE rating is actually the percentage of the fuel the furnace uses to heat your home. The minimum stands at 78, which means that 22 percent of the fuel is wasted in the heating process. The most efficient furnaces have an AFUE of 99, and in a mild climate like ours, will have a longer payback period, since our heating season is short.


SEER (seasonal energy efficiency ratio) indicates the cooling efficiency of air conditioners and heat pumps. Of the HVAC terms, this one impacts your energy budget more than having a high AFUE system because of our prolonged cooling season. The SEER minimum is 13 and systems are available that go into the low 20s. Cooling systems are tested to find the electricity they use under simulated conditions. The outdoor air is kept at 82 degrees F and a space cooled to 80 degrees with 50 percent humidity. Its power consumption is measured over a season to arrive at the SEER.

Another way that the efficiency of air conditioners is tested is under conditions we experience more often during the cooling season. Engineers measure the EER (energy efficiency ratio) at an outdoor temperature of 95 degrees to cool a space to 80 degrees. The SEER is readily apparent on cooling systems; the EER is harder to find, but just as important.


Heat pumps both cool and heat. The HSPF stands for heating season performance factor whose minimum starts at 7.7 and may reach 10 in systems that have scroll compressors that deliver more heat.

To learn more about these HVAC system terms and your energy budget, contact Beyer Boys. We’ve provided trusted HVAC services for the greater San Antonio area since 1990.

Our goal is to help educate our customers in the greater San Antonio, Texas area about energy and home comfort issues (specific to HVAC systems).

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