As you shop for a new central furnace, there are primarily three main product feature consideration you need to make. They are efficiencies, stages of heating, and motor types. Today we are going to cover the efficiency option.
All major furnace manufacturers offer standard efficiency and high efficiency models of their furnace lines. Standard means 80% AFUE which is the minimum requirement mandated by the federal government. High efficiency models can be anywhere in the 91%-96% AFUE range depending on brand, capacities, and model. For comparison, the 30 year old furnace in your closet is probably a 60-70% AFUE model so you will see a drop in gas consumption even by replacing it with the standard model. If you want to save even more the high efficiency models are good bets. However, high efficiency models are not always possible in certain situations because they require a separate flue pipe for the combusted air and an extra condensate line. A licencsed contractor need to survey your existing installation to determine if the upgrade is possible. PG&E and federal government have rebates and tax credit to encourage homeowners to upgrade to the high efficiency models.