Instant Hot Water-Maybe by Alex Wilson Demand or instantaneous water heaters have been widely used in Europe for several decades and have been available in this country for ten years. They have been extensively promoted through advertising campaigns, magazine articles, and building trade shows. Demand water heaters only heat water as it is used, so there are no stand-by losses-the primary culprit of low efficiency in conventional water heaters. Yet demand water heaters have failed to achieve a significant market share in the U.S. In fact after numerous calls to progressive builders in my region, I was unable to find a single builder who regularly (or even occasionally) installs them into homes. Why? Counter-intuitive techniques had to be learned to regulate water temperature. It took practice, and
