Noritz 6.6 GPM 140,000 BTU Residential Natural Gas Outdoor Tankless Water Heater (.82 UEF)

The Noritz NR662-OD-NG 6.6 GPM 140,000 BTU Residential Natural Gas Outdoor Tankless Water Heater delivers reliable, on-demand hot water while helping reduce energy consumption by heating water only when it's needed. Unlike traditional storage tank water heaters that keep a reserve of hot water continuously heated, the NR662-OD-NG provides an endless supply of hot water without standby energy loss, making it an excellent solution for homeowners seeking efficiency, performance, and long-term reliability.

Designed exclusively for outdoor installation, the NR662-OD-NG requires no additional venting, simplifying installation while saving valuable indoor space. Delivering up to 140,000 BTU of natural gas heating power and a maximum flow rate of 6.6 gallons per minute, this compact wall-mounted tankless water heater is well suited for condominiums, townhomes, apartments, and single-family homes with one to two bathrooms. Its commercial-grade copper heat exchanger, fully modulating burner, built-in freeze protection, and user-friendly temperature controls provide dependable hot water for everyday residential use.

Product Features:

• 140,000 BTU Maximum Input: Provides dependable natural gas heating capacity for residential hot water applications.
• Up to 6.6 GPM Flow Rate: Delivers continuous hot water to multiple fixtures including showers, sinks, dishwashers, and washing machines, depending on incoming water temperature and household demand.
• Outdoor Installation: Designed exclusively for outdoor installation, eliminating the need for vent piping while helping simplify installation.
• Non-Condensing Design: Provides reliable performance with a Uniform Energy Factor (UEF) of 0.82 while heating water only when needed.
• Commercial-Grade Copper Heat Exchanger: Heavy-duty copper heat exchanger is engineered for long-lasting residential durability.
• Compact Wall-Mounted Design: Saves valuable indoor space while providing convenient outdoor installation.
• Adjustable Temperature Settings: Factory default temperature is 120°F with adjustable settings from 115°F to 140°F when used with the optional remote controller.
• Fully Modulating Burner: Automatically adjusts between approximately 15,000 and 140,000 BTU to maintain consistent outlet water temperatures while improving energy efficiency.
• Built-In Freeze Protection: Helps protect the unit in outdoor temperatures down to -4°F when installed according to manufacturer requirements and connected to power.
• Recirculation Compatible: Compatible with properly designed external hot water recirculation systems.
• Built-In Safety Features: Includes flame sensing, overheat protection, fan rotation monitoring, lightning protection, temperature lockout, high elevation adjustment, and advanced self-diagnostic monitoring.

What Is an Isolation Valve Kit?

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

Routine flushing helps remove mineral buildup inside the heat exchanger, especially in areas with hard water. Installing isolation valves makes maintenance faster and easier while helping preserve efficiency and extend the life of the water heater.

Short vs. Long Isolation Valve Kit

For the Noritz NR662-OD-NG, only one isolation valve kit is required depending on the available installation space.

• IK-WV-200-5-TH-S Short Isolation Valve Kit: Ideal for installations where space is limited or a compact plumbing layout is preferred.
• IK-WV-200-5-TH-L Long Isolation Valve Kit: Recommended 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 appropriate kit depends on the installation layout and available working space.

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 tank capacity. Flow rate is the amount of hot water the unit can deliver each minute, while temperature rise is the difference between the incoming groundwater temperature and your desired hot 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 the 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 in 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 simultaneous hot water demand.

Warranty

The NR662-OD-NG includes Noritz's residential limited warranty featuring a 12-year heat exchanger warranty for standard residential use, a 5-year parts warranty, and a 1-year reasonable labor warranty. When used with a recirculation system, the heat exchanger warranty is reduced to 3 years. Always verify natural gas supply, installation location, water quality, electrical requirements, local plumbing and mechanical codes, and all required accessories prior to installation.