Noritz 9.8 GPM 199,900 BTU Residential Natural Gas Single Vent Tankless Water Heater (.82 UEF)

The Noritz NR98-SV-NG 9.8 GPM 199,900 BTU Residential Natural Gas Single Vent Tankless Water Heater delivers an endless supply of on-demand hot water while helping reduce energy consumption by heating water only when a hot water fixture is in use. Unlike traditional storage tank water heaters that continuously maintain a limited amount of heated water, the NR98-SV-NG heats water as it flows through the heat exchanger, eliminating standby energy loss while providing reliable hot water whenever your household needs it. Its high-capacity output makes it an excellent choice for larger homes with multiple bathrooms and high simultaneous hot water demand.

Designed for indoor installation, the NR98-SV-NG utilizes a single vent (power vent) configuration that exhausts combustion gases through an approved 4-inch Category III stainless steel vent system while drawing combustion air from the installation space. Delivering up to 199,900 BTU of natural gas heating power and a maximum flow rate of 9.8 gallons per minute, this compact wall-mounted tankless water heater combines commercial-grade durability, advanced safety features, and precise temperature control to provide years of dependable residential hot water performance.

Product Features:

• 199,900 BTU Maximum Input: Provides powerful natural gas heating capacity for larger residential homes with multiple bathrooms and high simultaneous hot water demand.
• Up to 9.8 GPM Flow Rate: Delivers continuous hot water for multiple showers, bathtubs, sinks, dishwashers, washing machines, and other fixtures simultaneously, depending on incoming water temperature and required temperature rise.
• Single Vent (Power Vent) Installation: Designed for indoor installation using an approved 4-inch Category III stainless steel vent system to safely exhaust combustion gases while utilizing indoor combustion air.
• Non-Condensing Design: Delivers dependable on-demand performance with a Uniform Energy Factor (UEF) of 0.82 while heating water only when hot water is needed.
• Commercial-Grade Copper Heat Exchanger: Manufactured with commercial-grade copper tubing approximately 25% thicker than standard residential heat exchangers for exceptional durability, efficient heat transfer, and long service life.
• Fully Modulating Burner: Automatically adjusts from approximately 16,000 to 199,900 BTU to maintain consistent outlet water temperatures while maximizing natural gas efficiency.
• Adjustable Temperature Settings: Includes a remote thermostat with adjustable temperature settings from 100°F to 140°F in 5°F increments, allowing precise residential hot water control.
• Quick Connect Compatible: Two identical NR98 Series units can be connected using the optional Noritz Quick Connect Cord to nearly double available hot water capacity without requiring an additional controller.
• Scale Detection Function: Built-in maintenance reminder helps notify homeowners when flushing and descaling are recommended to maintain peak performance, efficiency, and long-term reliability.
• Built-In Freeze Protection: Helps protect the heat exchanger during freezing temperatures when installed according to manufacturer guidelines and connected to electrical power.
• Advanced Safety Features: Includes flame sensing, overheat prevention, fan rotation monitoring, lightning protection, thermal fuse protection, temperature lockout, high elevation adjustment, and advanced self-diagnostic monitoring.
• Compact Wall-Mounted Design: Saves valuable floor space while allowing convenient installation and easy future servicing.

What Is an Isolation Valve Kit?

An isolation valve kit is a recommended accessory for every tankless water heater installation. These valves connect to the hot and cold water lines and allow the water heater to be isolated for flushing, descaling, maintenance, or servicing without shutting off water to the rest of the home.

Routine flushing removes mineral buildup that naturally accumulates inside the heat exchanger over time, especially in areas with hard water. Installing isolation valves makes annual maintenance significantly easier while helping preserve efficiency, improve performance, and extend the service life of the water heater.

Short vs. Long Isolation Valve Kit

For the Noritz NR98-SV-NG, only one isolation valve kit is required depending on your installation layout.

• IK-WV-200-5-TH-S Short Isolation Valve Kit: Recommended for installations where available space is limited or a compact plumbing arrangement is preferred.
• IK-WV-200-5-TH-L Long Isolation Valve Kit: Ideal when additional clearance is available, allowing easier future maintenance and servicing.

Both isolation valve kits include durable 3/4-inch threaded hot and cold isolation valves together with a lead-free pressure relief valve. The correct kit depends on the available installation space and plumbing layout.

Understanding Tankless Water Heater Sizing

Unlike traditional storage tank water heaters, tankless water heaters are sized using flow rate (GPM) and temperature rise rather than storage capacity. Flow rate represents the amount of hot water the unit can produce each minute, while temperature rise is the difference between the incoming groundwater temperature and your desired outlet water temperature.

Always size a tankless water heater using your area's winter groundwater temperature, since colder incoming water requires more heating capacity and reduces the maximum available flow rate.

For example, if your desired hot water temperature is 120°F and your incoming groundwater temperature is 50°F, the required temperature rise is:

120°F − 50°F = 70°F Temperature Rise

Use the Noritz flow rate chart included with the product literature to determine the expected hot water output at your required temperature rise. This helps ensure the water heater is properly sized for your household's peak simultaneous hot water demand.

Warranty

The NR98-SV-NG includes Noritz's residential limited warranty featuring a 12-year heat exchanger warranty for standard residential installations, a 5-year parts warranty, and a 1-year reasonable labor warranty. When installed with a controlled recirculation system using a minimum aquastat pump control, the heat exchanger warranty remains 12 years or 6,500 operational hours, whichever occurs first. Always verify natural gas supply, approved Category III stainless steel venting requirements, electrical requirements, water quality, local plumbing and mechanical codes, and all required accessories before installation.