This research project is focused on opportunities for achieving near-term energy efficiency gains in heating appliances, specifically high-efficiency, low-cost, boilers with integrated tankless coils for domestic hot water. The project begins with an evaluation of commercially available tankless coil boilers and potential low-cost technical improvements. The Contractor shall evaluate the performance of (6) of these boilers in a laboratory setting in order to evaluate the thermal, seasonal, and annual efficiency. Following the laboratory evaluation, the Contractor shall develop a Best Practices Guide for Tankless Coil Boilers. The project concludes with the dissemination of the Best Practices Guide as well as the publication and conference presentation of any technical papers developed from the laboratory evaluation.