AFUE Numbers For Boilers Translated

September 12, 2011

Efficiency translates to value. When it comes to your boiler, it’s important to understand just how efficiency ratings work. This way, you know exactly how energy is used, how much is wasted, and what you can do about it.

The performance of boilers is rated by the Annual Fuel Utilization Efficiency (AFUE) percentage. AFUE essentially compares the amount of heat a boiler produces to the amount of fuel it consumes. With higher AFUE ratings, the more fuel is changed into heat. So for instance, a boiler with an AFUE of 95 percent converts 95 percent of the fuel it uses into warmth for your home. What happens to the other 5 percent? It leaks out through the chimney, and other places.

Currently, the US government mandates minimum AFUE ratings for boilers based on fuel type. Different kinds of fuel, when combusted, have different levels of efficiency.

  • Fossil-fueled systems must have at least an 80 percent AFUE.
  • Gas-fired, steam models must have at least a 75 percent AFUE.
  • Electric boilers experience hardly any energy loss, and are typically between 95 and 100 percent efficient. However, they’re not always the most economical choice, as operating costs can be high for electric models.

Condensing boilers are some of the most efficient systems of all, sometimes saving 10 percent more on energy consumption than other systems. They also typically have low operating costs, which means condensing models are usually wise investments, especially in Johnson County where winters can be brutal.

However, AFUE alone doesn’t determine the performance of boilers. Many factors throughout your household contribute to performance, such as the efficiency of your ductwork. According to the Department of Energy, the average Johnson County home can lose around 35 percent of energy produced by the boiler due to inefficient ductwork and piping. This means that heated, conditioned air can leak out through cracks, and get lost via heat transfer from surface to surface, through un-insulated metal.

If you have questions about boiler performance or factors that affect efficiency, call Santa Fe Air Conditioning & Heating. We’ll be happy to answer your questions!