Rating numbers indicate the efficiency of heating and air conditioning equipment and are directly related to the amount of energy a specific model uses. The higher the rating, the more efficient the product, and the lower your heating and cooling bills can be. The federal government establishes rating guidelines and sets minimum levels. For cooling, the rating is SEER (Seasonal Energy Efficiency Ratio).
Think of your air conditioner and furnace a part of a total system. That system will work better, long and more efficient if all it’s components are matched in capacity and efficiency. By the same token, a mismatched system – one that mixes old technology with new – could decrease system performance and overall comfort.