Noritz NCC1991-OD 11.1 GPM Outdoor Natural Gas Condensing Tankless Water Heater
Get an energy efficient, endless, hot water at a low installation cost.
The NCC1991 is the most efficient Low NOx commercial condensing tankless heater from Noritz. This innovation uses a dual heat exchanger - a combination of copper and stainless steel heat exchangers. The stainless steel component traps residual heat from the exhaust and uses it to preheat incoming water before it passes through the main copper heat exchanger. The result is a dramatic reduction of carbon dioxide with an increase of the heater's efficiency level to 93%. Another benefit is lower exhaust temperatures, which means that you can use less costly PVC for venting.
Note: Only 3" or 4" PVC venting can be used on condensing heaters.