Skip to content
Enjoy fast and free shipping on all orders over $89! Contact us (855) 424-4376
Enjoy fast and free shipping on all orders over $89! Contact us (855) 424-4376
This unique Commercial Hybrid system combines all the benefits of the Rinnai C199 Condensing Tankless Water Heater with a 119-gallon storage tank and provides a direct replacement for most traditional and high efficiency commercial tanks. Along with Rinnai's reputation for quality and reliability, all parts are replaceable and easily serviced. The result is a superior performing product designed to reduce the need for frequent tank replacements.

You spend your business day multi-tasking - why shouldn't your commercial hot water system do the same? Introducing the Demand Duo™ - the perfect solution for direct replacement of most traditional standard and high efficiency commercial tanks. And Rinnai backs it's nearly 100-year reputation of quality and reliability with a 6-year HEX/Tank warranty.* The all new Rinnai Demand Duo™ is a master multi-tasker you're sure to admire.

Demand and Supply

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.

Ultimate Efficiency

Equipped with the all new C199 Tankless Water Heater which is Commercial ENERGY STAR® certified, has 96 percent thermal efficiency, 199,000 BTU, fueled by either Natural Gas or Propane, the Demand Duo™ produces consistent water temperatures for predictably smooth business operations. Optimum performance is achieved by efficient tank recovery methods so you can count on having hot water even during reheat cycles.

Strength In Numbers

With the ability to install multiple Demand Duos™ together, we create redundancy that keeps hot water flowing - and your business going.

Peace-of-Mind Monitoring

The effort to keep hot water availability and business up-time high doesn't stop with the hybrid system itself. The Demand Duo™ can also tie into a building management system with the DPS/MIS accessory, ending alerts when the system needs attention. In addition, the maintenance alert system on the Rinnai built-in controller provides peace of-mind monitoring protection to put the efficiency and performance of your hot water on cruise control.

Demand Duos™ Highlights:

    • Warranty: 6-year heat exchanger / tank, 5-year parts and up to 2 years labor*
      • Built standard with C199 Commercial Tankless Water Heater
      • Commercial ENERGY STAR® certified with 96% Thermal Efficiency
      • Ultra Low NOx compliant
      • 199,000 BTU
    • Approved for high altitude up to 10,200 ft (3,109 m)
    • Integrated temperature controller that provides 98°F to 185°F (no external controller required)
    • Fueled by Natural Gas or Liquid Propane
    • Assembled with individually certified components
    • First Hour Rating: 315 gal / Recovery: 231 gal (@ 100°F)
    • Multiple venting options (concentric, two pipe, room air, common vent)
    • Perfect for emergency replacement situations - connection locations similar to most popular high efficiency tanks
    • Easy and cost effective maintenance - all parts replaceable

    Blog posts

    See more

    Compare products

    {"one"=>"Select 2 or 3 items to compare", "other"=>"{{ count }} of 3 items selected"}

    Select first item to compare

    Select second item to compare

    Select third item to compare

    Compare