Navien NHB Gas Boilers
Review and Buying Tips

Navien condensing boilers from the NHB series, with the maximum size of 24” x 17” x 13” and with the lower power output, are the smallest units from this manufacturer. They are designed for efficient potable water and hydronic heating in small residential and light commercial applications.

Navien NHB boilers

The NHB boilers are available in four sizes, all Energy Star approved, whose metal fiber premix burner can provide the power up to the maximum of 150,000 BTU/H (depending on the model) while modulating gas valve allows the unit to deal with the reduced water flow efficiently.

For example, the most powerful model, NHB-150, has the highest Turn-Down Ratio - TDR of 15:1, which helps maintain the efficiency high and eliminate short cycling while keeping it from wearing out prematurely.

An advanced gas burner design delivers efficient work and cleaner gas combustion, resulting in lower NOx emission.


  • NHB-55
  • NHB-80
  • NHB-110
  • NHB-150

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Features and benefits

The superb efficiency results from the use of two heat exchangers, both made of long-lasting stainless steel and thanks to the constant air/gas mixture ratio.

The integrated smart controls found on the front panel, like other condensing boilers, include the push buttons for the temperature and heating mode change, LCD display, and icons that show the basic info such as the temperature and water flow error code for easy troubleshooting.

Other parameters that can be adjusted are a timed hydronic supply water boost, anti-cycle timer, outdoor temperature, minimum burner time setting, turn down ratio timing...


All the models are designed as the forced draft direct vent models for indoor use and wall mount, while the field conversion capability allows easy conversion from the natural to propane gas.

There are two vent connections at the top of the units; one is for the combustion air intake and the other for transferring the products of combustion out (exhaust).

All the condensing boilers, including this one, have the lower temperature of the exhaust gases, allowing better materials for vent pipes such as PVC, CPVC, or PP, which is easier and cheaper to install. The size of the vent pipes is 2” and 3”, and the maximum length is 60 or 150 feet.

Safety features

For safe and durable operation, Navien is designed with several safety features:

  • Freeze protection to protect the internal elements from freezing temperatures.
  • Power interruption eliminates the need for a manual reset, as the unit will automatically restore its operation after a power interruption, ignition, and flame detector electrodes.
  • Carbon-Monoxide protection
  • Auto-fan detection
  • Boiling protection
  • Short-circuit protection
  • Lighting protection

Similar tankless and condensing models:


Navien NHB condensing boilers are ideal for small homes and apartments where the advanced features ensure excellent energy efficiency and outstanding performance. At the same time, the quality elements allow Navien to provide an extended warranty of 15 years in residential applications and 10 years in a commercial.


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