Guide to High Performance Hydronics: by John Seigenthaler Condensing boilers work best in low-temperature applications. For other uses, consider power venting and boiler purging. By capturing residual heat during the boiler's off-cycle, the System 2000, from Energy Kinetics, achieves near the efficiency of condensing boilers without the complications. Since the energy crisis in the early 1970s, manufacturers have devised a number of new strategies aimed at extracting more heat from a given amount of fuel. At the same time, they've developed new approaches to handling exhaust gases and reducing off-cycle heat losses. This article will take a brief look at these new approaches, and provide some practical guidance for their selection and use. Condensing Boilers Until recently,