The energy efficiency of a boiler is determined by fuel utilization efficiency (AFUE), a measure of how efficiently the appliance uses fuel over the course of a typical year. The AFUE is a ratio of heat output compared to the total energy consumed by a furnace or boiler. The Federal Trade Commission now requires new furnaces or boilers to display their AFUE rating so that consumers can compare the heating efficiencies of various models.
In addition to finding the AFUE rating, the energy efficiency of a boiler can also be determined by its equipment features. According to the Energy Savers website, on an old model boiler, these features include:
Low-efficiency heating systems:
- Natural draft that creates a flow of combustion gases
- Continuous pilot light
- Heavy heat exchanger
- 68%–72% AFUE
Mid-efficiency heating systems:
- Exhaust fan controls the flow of combustion air and combustion gases more precisely
- Electronic ignition (no pilot light)
- Compact size and lighter weight to reduce cycling losses
- Small-diameter flue pipe
- 80%–83% AFUE
High-efficiency heating systems:
- Condensing flue gases in a second heat exchanger for extra efficiency
- Sealed combustion
- 90%–97% AFUE
To increase the efficiency of your boiler, consider retrofitting or replacing your boiler. In many cases, replacing your existing boiler may make more sense and save money in the long run.
Replacing your boiler is recommended if your boiler is more than 15 years old, inefficient, is significantly oversized, or was once a coal-burning model that has been converted to oil or gas burning. Other boilers that should be replaced with energy efficient models are gas boilers with pilot lights rather than electronic ignitions.
A new boiler with energy efficient features will be smaller and use less fuel to save you money on energy bills. Call Rodenhiser for a free estimate if you think it may be time to replace your boiler.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about high efficiency boilers and other HVAC topics, download our free Home Comfort Solutions Guide.