Condensing Boilers--Are They Cost Effective?


High-efficiency condensing boilers have been available in the residential market for many years, but consumer acceptance and market penetration has remained low. Furthermore, there is a lack of confidence by many contractors and utilities about the energy savings attributable to this technology over a non-condensing version-particularly in the retrofit market. 

To address these concerns and uncertainty, our research team monitored thirteen condensing boilers in Minnesota homes to characterize installed performance. Six of these were installed up to seven years prior to the project and seven were installed using a Quality Installation protocol developed during the project.  

We have data on supply and return water temperature, flow rates, incidence of condensing, and energy usage for all thirteen systems. These systems represent a variety of single family residential installations with various brands, emitter types, zone set-ups, and outdoor reset control installation and set points. These homes also represent a range of house types and heating loads in Minnesota. 

In this paper, we will discuss the usage and performance findings from this monitoring and the impact of installation and recommissioning procedures on boiler performance. We will show that condensing boilers in Minnesota homes are generally achieving high performance without requiring a specialized site-specific installation. We will discuss the results of our market analysis, including HVAC contractor and homeowner surveys and cost comparisons on over 70 installation bids. We will also include our recommendations for easy to implement Quality Installation activities to improve system performance. 

Download the paper (PDF):
Condensing Boilers--Are They Cost Effective? 

Related Resources
Project Page: Retrocommissioning of Condensing Boilers