The efficiency of any furnace is measured in Annual Fuel Utilization Efficiency (AFUE). AFUE shows how much of the fuel you pay for is actually turned into usable heat. The higher the AFUE, the less fuel you'll need to keep your house, business, or building comfortable. If you have a furnace that is at least 10 years old, it probably needs to be replaced. Contact us today at Erik Diaz Heating & Air to set up a consultation.