With Rinnai s new Demand Duo H-Series, reliable hot water comes in a high-performance, high-efficiency package that also reduces cost of ownership. Rinnai s hybrid technology is unlike anything else on the market, ensuring a longer service life than high-efficiency tanks, while also saving valuable commercial space. The tankless engines for the Demand Duo 2V are stacked vertically to deliver redundancy and eliminate "no hot water" events that affect profitability.