Extra large high output cupronickel heat exchanger increases performance by 20% or more, supplying recovery capacities 3-5 times higher than conventional designs (including electric models) and delivering larger amounts of hot water in less time and for longer periods (depending upon boiler supply capacity and hot water draws).   Corrosion-resistant stainless steel tank with environmentally-safe CFC-free water-blown foam insulation allows less than ½°F per hour heat loss.   Full line of seven different models and sizes to meet virtually any hot water application.   Lifetime limited warranty protection plan.