Combining the on-demand' continuous supply technology of the Rinnai C199 tankless with an energy efficient and durable 119-gallon storage tank' the Demand Duo™ provides more water heating capacity than a traditional tank in the first hour. The result: Hot water is available to keep pace with demand from short-period' high-spike draws' to a supply that’s ready to go the distance' day in and day out.

• Built standard with C199 Commercial Tankless Water Heater
• Comercial Energy Star certified
• 96% Thermal Efficiency
• Approved for high altitude up to 10'200 ft
• Integrated temperature controller that provides 98°F to 185°F
• Natural Gas or Liquid Propane
• Multiple venting options (concentric' two pipe' room air' common vent)
• Perfect for emergency replacement situations – connection locations similar to most popular high efficiency tanks