If your heating equipment was on the fritz at the end of last heating season, the time is now to upgrade your furnace. Amongst other things, it is imperative that you know how to read and understand the annual fuel utilization efficiency, or AFUE ratings that are displayed on all new furnace models. Here's why:What AFUE isAFUE ratings are a measurement of how well a furnace is able to change the energy within its fuel into usable heat throughout the course of a year. To be more specific, AFUE serves as the ratio of the furnace's annual output of heat versus the total amount of energy that is consumed by the boiler. All new heating equipment including both furnaces and boilers is required to display AFUE ratings so that consumers are able to easily make comparisons between the efficiency of various models.What the numbers meanWhen it comes to AFUE, the larger the number you see, the more efficient the furnace is. As an example, if a furnace has been assigned an AFUE rating of 85 percent, you will know that 85 percent of the energy from its fuel will be efficiently converted into heat from your home. The remaining 15 percent will be lost through your flue pipe, pilot light, or other means of losing efficiency.Other considerations when looking at AFUE ratingsFirst, it is important to keep in mind that AFUE does not take the losses of heat within your duct system or piping into consideration. If your home's ducts are located in your attic, you can expect that as much as 35 percent of your furnace's energy output could be lost. Your HVAC contractor can advise you on the best heating systems for a home with such a duct system. In addition, you should know that bigger is not always better with AFUE. Electric furnaces tend to have AFUE ratings between 95 - 100 percent, for example, but the higher costs of electricity over gas make these an uneconomical decision.For more advice on understanding furnace efficiency ratings, contact the professionals at Air Assurance. We proudly serve residents of the Tulsa and Broken Arrow areas.Our goal is to help educate our customers in the Tulsa and Broken Arrow, Oklahoma area about energy and home comfort issues (specific to HVAC systems). Image courtesy of Shutterstock