Noritz NR663 (EZTR40) 
Tankless Water Heaters 
Review and Buying Tips

An overview of the Noritz NRC663 tankless water heater, also known as the Noritz EZTR40; features, specifications, benefits, where to use, installation tips.



Condensing technology

Noritz NRC663-EZTR40

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Noritz NRC663-FSV, also known as Noritz EZTR40, is the small tankless water heater that uses condensing technology for on-demand, high-efficiency water heating in residential applications.

Due to its maximum gas input of 120,000 Btu and hot water flow of 6.6 gallons per minute, the EZTR40 is recommended for smaller houses, apartments, cabins, cottages, apartments, and offices in regions with the warmer climate, covering up to 2 baths with a continuous supply of hot water.

Fuel options

These water heaters can utilize both natural and propane gas, allowing usage in cabins and cottages where the natural gas is not accessible while the propane can be delivered. With the appropriate setup, the EZTR40 can also be installed in the higher elevation (mountains).


The EZTR40 model is an indoor, power-vented unit that utilizes an electric fan to blow the gases out through the 2" flexible pipe. The water heater gets the indoor air for the gas combustion through the air filter and provided slots at the front cover.

Noritz EZTR40 offers a new approach in tankless water heater installation, top mount water connections, and convenient venting directly through the existing 3" and 4" B-vent.

This setup allows faster installation, making them ideal for retrofits to replace the existing storage tank-type water heaters using the same gas, water, and vent lines.

Due to its low NOx gas emission models can be used in regions with strict laws for pollution and emission of greenhouse gases.


EZTR40 has the ability, using the modulating gas valve, to operate in the power range from 15,000 to 120,000 Btu while still providing excellent energy efficiency of 0.91 (for both natural gas and propane types), which guarantees reduced energy usage and decent savings.

Compact size

EZTR40 is a very small wall-mount unit: 27.2" x 18.3" x 9.4" in size and only 50 lbs. in weight, making them ideal for installation in places that lack floor space, laundries, and bathrooms, for example.


Like other Noritz tankless water heaters, the EZTR40 is a reliable and safe unit; it is equipped with several safety devices and a display window that shows the numerical error code in case of failure.

This small and simple display also indicates the temperature and the operating status, and it is built-in at the front of the unit. If you need more convenience and more temperature settings, a remote controller is offered as an option.

Users can set the temperature between 115 and 140 F in six variants.

Safety features

  • Flame sensor
  • Thermal fuse
  • Overheat prevention system
  • Freeze protection to - 30 F for an indoor and -4 F for outdoor models (this applies to the heater's internal plumbing)
  • Lighting protection device
  • Condensate overfill
  • Fan rotation detector
  • Resin coated PC board for protection and durability


Models/Specs Noritz NRC663
Power (BTU) 15,000-120,000
Water flow (GPM) 0.5-6.6
max # of baths 2
Water/gas connections (inch) 3/4 and 1/2
Temperature (F) 115-140
Energy factor 0.87
Warranty 12/5


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