Retrocommissioning of High-Efficiency Condensing Boilers

This report is the result of the CARD program project Retrocommissioning of Condensing Boilers

Although high-efficiency condensing boilers have been available to consumers for a long time, they have yet to fully penetrate the market. Consumer acceptance continues to be a barrier, as well as lack of confidence by many contractors and utilities related to energy savings, cost-effectiveness, and quality installation.

To address these uncertainties, our research team monitored thirteen condensing boilers in Minnesota homes to characterize installed performance. Six of these boilers were installed up to seven years before the project began and seven were installed during it, using a project-developed Quality Installation protocol. The team collected data on supply and return water temperature, flow rates, incidence of condensing, and energy use across all thirteen systems – which represent a wide range of single-family installations with different brands, emitter types, zone set-ups, and outdoor reset control installation and set points. In addition, the team conducted interviews with contractors/distributors and homeowners, and performed an economic analysis.