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Warns about flammable vapors, storage, and properties.
Warns about burns from hot water (>125°F) and vulnerable groups.
Specifies safe locations for exhaust vents to prevent CO poisoning.
Advises on clearances and avoiding combustibles near the unit.
Stresses grounding importance and safe handling of power cords.
Advises on preventing freezing damage during non-use or cold weather.
Details opening water/gas valves and turning on power.
Explains setting temperature and high-temperature warning system.
Steps to turn off power, press alarm set, and use setting buttons.
Explains the unit's automatic freeze prevention and its limits.
Advises running hot water during extreme cold to prevent freezing.
Step-by-step guide to drain the water heater for long-term storage.
Addresses problems with unit ignition and failing to ignite.
Warns about flammable vapors, storage, and properties.
Warns about burns from hot water (>125°F) and vulnerable groups.
Specifies safe locations for exhaust vents to prevent CO poisoning.
Advises on clearances and avoiding combustibles near the unit.
Stresses grounding importance and safe handling of power cords.
Advises on preventing freezing damage during non-use or cold weather.
Details opening water/gas valves and turning on power.
Explains setting temperature and high-temperature warning system.
Steps to turn off power, press alarm set, and use setting buttons.
Explains the unit's automatic freeze prevention and its limits.
Advises running hot water during extreme cold to prevent freezing.
Step-by-step guide to drain the water heater for long-term storage.
Addresses problems with unit ignition and failing to ignite.
This document describes the Noritz Tankless Gas Water Heater, models N-0631S, N-0631S-OD, N-0531S, and N-0531S-OD. This appliance is designed to provide on-demand hot water, eliminating the need for a storage tank and offering energy efficiency.
The Noritz Tankless Gas Water Heater heats water as it flows through the unit, rather than storing a pre-heated supply. When a hot water fixture is opened, the unit senses the water flow and activates its burner to heat the water to a set temperature. This continuous heating process ensures a constant supply of hot water, ideal for residential applications. The unit is equipped with an automatic ignition device, meaning there is no pilot light to manually ignite. It also features a freeze prevention heater to protect internal components in cold weather, though external plumbing may require additional protection.
Initial Setup and Operation: Before initial use, the water supply valve and gas supply valve must be fully opened. A hot water fixture should be opened to confirm water availability, then closed. Finally, the electrical power to the unit must be turned on.
Temperature Setting: The factory default temperature setting is 120°F. For models with a remote controller (RC-7649M), the temperature can be adjusted between 100°F and 150°F in 5°F intervals, with additional default options at 120°F, 130°F, and 140°F. For units without a remote controller, the temperature is fixed at 120°F, and mixing with cold water at the fixture is required to achieve a desired temperature. If a higher fixed temperature (130°F or 140°F) is desired for units without a remote controller, an installer or Noritz must be contacted. When setting the temperature to 125°F or higher using the remote controller, the display will flash for 10 seconds and emit a tone as a high-temperature warning, emphasizing the risk of scalding. It is crucial to check the water temperature before bathing or showering, especially for children, the disabled, and the elderly, who are at higher risk of scalding. Temperature limiting valves are available for added safety.
Remote Controller (RC-7649M)
Flow Meter Alarm: This feature allows users to set an alarm to sound when a specific volume of hot water has been dispensed, useful for filling bathtubs. Settings can be chosen from 10-60 gallons (in 5-gallon intervals), 70-100 gallons (in 10-gallon intervals), or 990 gallons. The alarm will sound for ten seconds when the set level is reached, but the water will continue to run unless manually turned off. The alarm will not sound if set to 990 gallons. It's important to note that if other hot water fixtures are used simultaneously, the tub may not fill to the set volume, or if water is already in the tub, it may overflow if not manually shut off.
Maximum Output Temperature Adjustment: The upper limit of the hot water supply temperature can be adjusted using the remote controller. This involves turning off the power, pressing and holding the flow meter alarm set button until a sound is heard, then using the setting buttons to change the maximum temperature (e.g., 100°F, 105°F, 110°F, 115°F, 120°F, 125°F, 130°F, 135°F or 140°F). After adjustment, the power button should be set to ON to continue use.
Safety Precautions: The manual emphasizes critical safety information, including warnings about flammable vapors, scalding hazards, and carbon monoxide poisoning. Users are advised not to store or use flammable products near the water heater. Temperatures over 125°F can cause severe burns. For indoor models, proper exhaust venting is crucial to prevent carbon monoxide buildup. If a gas leak is suspected, users must immediately stop using the appliance, close the gas valve, open windows and doors (if indoors), and contact the gas supplier or fire department. The temperature and pressure relief valve should never be plugged or removed.
Periodic Inspection: Regular inspections are recommended to ensure safe and efficient operation. This includes checking for:
Water Drain Valve (with Water Filter) Cleaning: If the water drain valve or filter is covered with debris, it can affect hot water flow or cause the unit to dispense cold water. To clean:
Preventing Damage from Freezing: The unit has an automatic freeze-prevention heater for internal components, which operates regardless of whether the unit is on or off, as long as the power plug is connected. However, external plumbing requires additional protection (insulation, heat tape, etc.). In extremely cold conditions (below -30°F for indoor installation or -4°F for outdoor installation), additional measures are necessary:
Draining the Unit for Long Periods of Disuse: If the water heater will not be used for an extended period, it should be drained to prevent water damage. This involves:
General Cleaning: The outside surface of the unit can be wiped with a wet cloth and dried. A neutral detergent can be used for stains. The remote controller should also be wiped with a wet cloth, avoiding benzene, oil, or fatty detergents to prevent deformation. While water resistant, the remote controller is not waterproof and should be kept as dry as possible.
Optional Maintenance (Isolation Valves): Isolation valves can be purchased as an accessory from Noritz. These allow for full diagnostic testing and easy flushing of the system. The kit includes two full port isolation valves and a pressure relief valve for the hot side.
Troubleshooting: The manual provides a detailed troubleshooting guide for common issues such as failure to ignite, temperature fluctuations, insufficient hot water, and error codes displayed on the remote controller. It advises users to check gas and water supply, filter cleanliness, and temperature settings before contacting Noritz America Technical Support.
Warranty and Service: A warranty registration card is included separately and should be filled out and mailed. For service, users are asked to provide the model, date of purchase, details of the problem (including error codes), and contact information. Noritz will stock repair and maintenance parts for ten years from the date of original installation. Reinstallation in a different location or conversion for a different gas type requires professional service.
General| Type | Tankless |
|---|---|
| Fuel Type | Natural Gas |
| Maximum BTU Input | 63, 000 BTU/h |
| Flow Rate | 6.3 GPM |
| Energy Factor | 0.82 |
| Weight | 38 lbs |
| Efficiency | 82% |
| Energy Source | Natural Gas |
| Input BTU/h | 63, 000 BTU/h |
| Venting | Direct Vent |
| Warranty | 12 years heat exchanger, 5 years parts |
