The company’s indirect water heaters are available in sizes to 8,000,000 Btuh with water heating capacities to 7,680 gal/hr at 100° temperature rise (40°F to 140°). The primary water in the heater is maintained at a constant temperature and recirculated only within the heating vessel. The heat exchanger, placed in the primary water, absorbs heat, and transfers it to the water flowing through its copper tubes. - Bryan Steam, LLC