The ESS water heater is a packaged system designed to meet the requirements of ANSI Z358.1-2009 for tepid water delivery to an emergency drench system. This heavy-duty water heater is constructed of a carbon steel tank and internally lined with 1/2″ thick Hydrastone cement to ensure tank longevity when operating at elevated temperatures, and is fully insulated with 3″ thick polyurethane foam to minimize stand-by heat loss.