The Demand Duo commercial hybrid water-heating system combines highly efficient heat-exchanger technologies with a durable 119-gal. tank. It produces more hot water in the first hour than traditional commercial systems, has a six-year heat-exchanger and tank warranty, and saves energy. Demand Duo provides a direct replacement for traditional standard and high-efficiency commercial tanks and features direct-vent, common venting options and single-unit/common-vent room-air ability using a building’s existing vertical vent penetration, eliminating the need to core additional holes in walls and roofs to allow for external ventilation.
—Rinnai Corp.