* Damage can occur from frozen water within the device and pipes even in warm environments.Be sure to read below for appropriate measures.* Repairs for damage caused by freezing are not covered by the warranty.Freezing cannot be prevented when the power plug is unplugged. Do not remove the powerplug from the wall outlet.Freezing will be prevented regardless of whether the operation switch is ON or OFF.Take the measures below for extremely cold temperatures*. Outside temperature including wind chill factor less than -30°F (-35°C) for NRC661-DV and NRC711-DVor -4°F (-20°C) for NR501-OD, NR662-OD, NRC661-OD, and NRC711-OD.- For models NRC661-DV and NRC711-DV, when supplying combustion air from the indoors, the roomtemperature must be greater than 32°F (0°C) to prevent freezing and the room inside must not have 3negative pressure.This method can protect not only the heater, but also the water supply, water piping and mixing valves.1. Turn off the Power On/Off Button.2. Close the gas supply valve.3. Open a hot water fixture, and keep a small stream of hot waterrunning. (0.1 gallon (400cc)/minute or about 0.2" (4mm) thick.)* If there is a mixing valve, set it to the highest level.4. The flow may become unstable from time to time.Check the flow 30 minutes later.* In general, it is not advisable to run water through the unit whenit is OFF, but in this case freeze prevention is more important.* Remember to set mixing valves and fixtures to their original levels before using the unit againto prevent scalding.* If there is still a risk that the unit will freeze, drain the unit as shown on the next page.Preventing Damage from Freezing-1Freezing is prevented within the device automatically by the freeze-prevention heater.If water will not flow because it is frozen1. Close the gas and water valves.2. Turn off the power button.3. Open the water supply valve from time to time to check whether water is running.4. When the water is flowing again, check for water leaks from the unit and piping before using.If the heater or the piping is frozen, do not use the heater or it may get damaged.CAUTION* In normal operation, freezing is prevented within the device automatically unless the outsidetemperature without wind is below -30°F (-35°C) for NRC661-DV and NRC711-DV or -4°F (-20°C)for NR501-OD, NR662-OD, NRC661-OD, and NRC711-OD.- For models NRC661-DV and NRC711-DV, when supplying combustion air from the indoors, the roomtemperature must be greater than 32°F (0°C) to prevent freezing and the room inside must not havenegative pressure.* The freeze prevention heaters will not prevent the plumbing external to the unit from freezing.Protect this plumbing with insulation, heat tape or electric heaters, solenoids, or pipe covers.If there remains a freezing risk, contact the nearest Noritz agent.0.2" (4mm)thickHot Water Fixture76
