Jim Lunt of the Lunt Marymor Co., offered a presentation on the possibilities and special issues that accompany condensing gas water heaters.

Most gas water heaters are only about 65 percent efficient. A lot of heat is lost up the flue. But condensing models offer efficiency in the 90s. They also come with special requirements.

Mr. Lunt takes you on a tour of a field installation of one, including its special needs and potential problems that can arise. The link goes to the ACEEE website, so if you want to return to waterheaterrescue.com, you'll need to hit the back button on your browser.