Annual Fuel Utilization Efficiency (AFUE) for Boilers
By ProMatcher Staff
Is a high-efficiency boiler worth it?
The overall efficiency of a boiler is measured by its annual fuel utilization efficiency (or AFUE). A boiler's AFUE rating is calculated by determining the percentage of fuel that is successfully converted into usable heat. A higher percentage indicates a more efficient boiler.
High-efficiency boilers are typically more expensive, but boilers can last for decades. The higher initial cost of a high-efficiency boiler will likely be recouped over the life of the boiler by lower energy bills.
How to Calculate AFUE
The efficiency of the boiler is calculated by dividing the heat output by the total energy consumed by the boiler. This calculation gives you the ratio of energy that is converted into usable heat.
The output of the boiler is most commonly measured in British thermal units (BTU). For example, If the heat output of your boiler is 80,000 BTU/hr and the total energy consumed by the boiler is 100,000 BTU/hr, the energy efficiency is 80%.
Boiler Efficiency Categories
Low-efficiency boilers
- 56-72% AFUE
- Continuous pilot light
- Typically found in older homes
Mid-efficiency boilers
- 80-85% AFUE
- Typically have an electric ignition
- More affordable to purchas than high-efficiency boilers
High-efficiency boilers
- 90-98% AFUE
- Condense water vapor to extract heat
- Tax incentives and rebates may be available
- Lower operating cost than other boilers
- Expensive initial cost
See the ProAnswer:
Is a boiler heating system (ie: radiant or hydronic) more energy efficient than a hot air furnace heating system?
DOE Efficiency Standards
The US Department of Energy now sets minimum standards for boiler efficiency. For example:
- Minimum standard for a gas-powered water boiler is 82%.
- Minimum standard for a gas-powered steam boiler is 80%.
You may also like:
+ How Much Does Boiler Installation Cost?
+ Boiler Capacity
About the Author
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| ProMatcher Staff, ProMatcher
Orlando, FL 32803
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