The Noritz NCC1991 is a high-efficiency condensing water heater. For the perfect mix of power and efficiency in a tankless water heater, the NCC1991 uses a stainless steel dual heat exchanger with condensing technology. This heat exchanger takes heat from the NCC1991′s primary flame in addition to capturing latent heat from burner exhaust. By applying both direct and indirect heat, the NCC1991 achieves thermal efficiency ratings of 93 percent, outstanding for a commercial water heater. The NCC1991 also makes use of a fully modulating burner. Instead of usual on/off functionality, the NCC1991 can match its burner intensity to the water heating demands of the home.
Like the NC250, the NCC1991 comes in multiple variations. The NCC1991-OD is an indoor/outdoor standard vented model, while the NCC1991-DV is an indoor hung direct vent model. Regardless of model, the NC1991 captures enough heat from its combustion gasses that it can be vented via inexpensive PVC pipe. Other water heaters, with hotter exhaust, require thermal-treated-and generally more expensive and cumbersome-vent pipe.
Even with its thermal efficiency and easy venting, the NCC1991 is still rated for up to 199,000 BTUs of heat per hour. Same as the NC250, the NCC1991 can be installed in a system of up to 24 Noritz tankless water heaters for larger applications. The NCC1991 can pump out over 11 gallons of water per minute at its peak. Even raising water temperature 45 degrees Fahrenheit, the NCC1991 flows at 8.5 gallons per minute. The NCC1991 can also be set up as a combi-system, allowing it to provide domestic hot water and hydronic heating water.