Navien NPE Gas Boilers
Review and Buying Tips

The Navien NPE series is another advanced group from this manufacturer that consists of the high-efficient and condensing tankless water heaters, all grouped in two categories, "A" and "S", and offering the following models:

  • NPE-150S, no “A” models
  • NPE-180 A/S,
  • NPE-210 A/S
  • NPE-240 A/S
Navien NPE boiler

Features and benefits

Differences between models

Navien NPE gas water heaters have many common features, while the main difference is that the "A" series has a built-in pump and the 0.4-gal buffer tank, also the pump drain port and the recirculation inlet.

Such a setup allows an internal or external recirculation, resulting in faster hot water delivery, a reduced number of cold-water sandwiches, and better user comfort. So if you need a water heater capable of providing hot water ultra-fast, buy an "A" model.

As the models are designed for indoor and outdoor installation, recirculation mode is also very beneficial during the cold weather as it protects the system from freezing up. The greatest benefits are on-demand heating and water preheating by utilizing the exhaust gases, resulting in increased thermal efficiency and hot water flow rate. This also includes the Intelligent Preheating Technology, which recognizes the pattern of how hot water has been used for added convenience.

Similar model: Rinnai RUR98

Ultra efficiency

According to the Navien manufacturer, NPE condensing tankless water heaters can provide a high energy efficiency of 0.99, which definitely outperforms the conventional, non-condensing type but models from its competitors.

The gas input for the non-condensing water heater is maybe higher, but the output is much lower (resulting in more energy waste). Moreover, when it compares to the tank-type, the savings are even higher.

Flexible installation

NoteProfessional installation and repair are recommended. Find local plumbers and get FREE Quotes!

The Navien NPE series is excellent for installations in new houses and as a retrofit when replacing the old conventional tank-type. Additional flexibility comes with the provided gas conversion kit, which allows every technician easy and convenient gas conversion, from natural gas to propane gas.

The efficient work, together with the simple and more flexible installation, saves time and money, making it a preferable water heater type among the house owners and technicians. There might be upfront, higher costs for the unit, but it pays off after several years, especially after considering that these units can run for at least 15 years with no problem.

Quality elements

Navien designs the NPE condensing water heaters with the two stainless steel heat exchangers, guaranteeing longer life and reliable operation.

The quality metal fiber gas burner with the ideal air/gas mixture allows cleaner combustion with the lox NOx emission, making the water heater operation Eco-friendly.

The front panel is where the user monitors and controls the water heater's operation. It consists of the LCD display where the user can view the operating status and use the push buttons for selecting the operation mode and temperature settings - up to 140 F in domestic hot water heating or 182 F in the commercial mode. For more convenience, the optional remote control can be used.

Installation and venting

There are two venting connections at the top of the water heater, both with the 2" or 3" diameter, one for the air intake and the other for the exhaust. They can terminate either vertically through the roof or horizontally through the sidewall with a maximum vent length of 150 feet. The vent pipes are made of PVC, CPVC, and PP - cheap to buy and easy to install.

Indoor models have the sealed combustion and forced direct vent, which allows safe operation where the water heaters use the fresh air from the outside and where the products of combustion are transferred.

Another great thing about the NPE series is the factory standard for the gas line; it uses ½" connections, which match the gas line inside the house, so no need for the additional expensive change.


The gas input rates are as follows:

  • NPE-150S – 18,000-120,000 BTU/H
  • NPE-180 A/S – 15,000-150,000 BTU/H
  • NPE-210 A/S – 19,900 – 180,000 BTU/H
  • NPE-240 A/S – 19,900 – 199,900 BTU/H

Flow rate

The water flow rate is in the range from 6.8 gal/min for the NPE-150S model to 11.1 gal/min for the NPE-240 A/S model (temp. rise 30 F), and in a case of higher hot water demand, up to 16 NPE units can be connected into the cascade system. For the "S" models, a minimum flow rate is 0.5 gal/min, so the water heaters can operate with the reduced water flow when needed. The flow rate can be seen on the control panel command center.


As seen from the above, Noritz NPE differs in BTU and also in weight, which is in the range from 55 lbs. to 75 lbs., while the size is the same for all; 17.3" x 27.4" x 13.2" - great for the wall installation and homes that lack in space.


The Navien NPE series offers high-performing and ultra-efficient tankless water heaters that bring convenience and comfort to its users. With the recirculation system and condensing technology, it saves money and time, eliminates the cold water sandwiches so showers are more pleasant, and it can last for a long time. The manufacturer covers the NPE series with the longest warranty of 15 years in residential applications and 10 years in the commercial.


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