Traditional vs. Condensing Gas Boilers. Traditional gas boilers burn natural gas or propane to heat the water in a home heating system. These boilers are vented to the outside via a chimney flue or vent pipe. Traditional boilers typically operate at higher temperatures, which means that a portion of heat is vented to the outside during the combustion process. Depending upon its age and type, a traditional non-condensing boiler will typically be 80% to 85% efficient.
ENERGY STAR Most Efficient 2018 — Boilers The ENERGY STAR Most Efficient 2018 designation recognizes the most efficient products among those that are ENERGY STAR certified. These exceptional gas and oil boilers represent the leading edge in energy efficient products this year.
Steam boilers operate at a higher temperature than hot water boilers, and are inherently less efficient, but high-efficiency versions of all types of furnaces and boilers are currently available. To learn more about furnaces, boilers and other types of home heating systems, explore our Energy Saver 101 infographic on home heating.