This product qualifies for a federal tax rebate of up to $600. Click here for details.Takagi T-H3-OS outdoor series tankless water heaters are among the most popular choices for on-demand condensing (high efficiency) gas tankless water heaters on the market due to their reliability, efficiency (0.95 UEF, Energy Star certified) and affordable price. These are high-ouptput models, designed mainly for high demand applications (multiple simultaneous showers/sinks/appliances) and are also suitable for commercial applications requiring 180F degree water.