Condensing Boilers

Condensing boilers capture the heat that is lost through steam in conventional boilers and are therefore more efficient. Under the right conditions, they will outperform conventional boilers by a substantial margin.GSA tested condensing boilers at the Denver Federal Center and the Peachtree Summit Federal Building in Atlanta, Georgia and found energy savings greater than 14%. View full-size infographic. [PDF - 233 KB]

GPG Findings 004, Updated July 2014, Condensing Boilers. Opportunity: How much Energy is used for heating in U.S. commercial buildings? 35% of energy goes to heating. 32% of commercial buildings rely on boilers to supply this heat.  Technology: How do Condensing Boilers save energy? Capture Heat that is lost through steam in conventional boilers. 95% efficiency. 15% more efficient than conventional boilers. Measurement and Verification: Where did M and V occur?  Pacific Northwest National Laboratory and National Renewable Energy Laboratory measured the performance of condensing boilers at both the Peachtree Summit Federal Building in Atlanta, Georgia and the Denver Federal Center. Results: How did Condensing Boilers perform in M&V?  Greater than 14% savings in natural gas consumption. Less than 130 degrees Fahrenheit return water temperature key to efficiency. 4 to 7 years payback at estimated typical costs. Return water temperature is key to efficiency. Lower RWT results in greater efficiencies. Deployment: Where does M and V recommend deploying Condensing Boilers?  End of Life Replacement of conventional boilers with condensing boilers. Life-cycle cost-effective even when only 3% to 5% more efficient than high-efficiency boilers. [PDF - 233 KB]

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Last Reviewed: 2021-05-21