SEER

The SEER, or Seasonal Energy Efficiency Ratio, rating. Like its "mpg" counterpart in the automotive industry, the SEER gives an indication of the performance efficiency of the system. The higher the SEER, the more efficient the unit. And, the more efficient the unit, the lower the operating costs.

SEER has no bearing on cooling power, a 3 ton 10 SEER will cool your home just as much as a 3 ton 14 SEER, However it will do the job using less energy, you save on your electric bill.