Get an efficient, high performance condensing gas boiler for limitless hot water.
The new NHB boiler series features the next line of innovations by Navien. All NHB boilers come with Navien's advanced burner system, the industry-leading AFUE of 95% and a turn down ratio of up to 7:1.
Ultra Condensing Efficiency
• Navien's condensing technology provides high efficiency heating
• Saves more money and energy than traditional water heaters and other boilers.
Two Stainless Steel Heat Exchangers
• Reduces minerals deposits.
• High resistance to corrosion and erosion means longer life expectancy.
Low NOx Emissions (less than or equal to 20ppm)
• Newly designed metal fiber burner delivers a consistent gas/air mixture, improving combustion efficiency.
• Less production of greenhouse gases and acid rain.
• Complies with strict SCAQMD 1146.2 NOx emissions standards.
2" CPVC, PVC, Polyprophylene Venting Up To 60 feet
• 2" venting option allows a flue to be pulled through existing vents.
• 3" vents can be used for up to 150 feet with 2" x 3" adapters.
• NHB heaters allow for easy convertibility from natural gas to liquid propane.
Powerful Anti-Freeze System
• The built-in Control System was designed to keep the unit frost free in winter conditions.
Hydronic Heating Benefits
• Economical, clean, silent, and comfortable
Utilizes Existing 1/2" Gas Line
• Negative Pressure Gas Valve with dual venturi operation allows better adaptability in low gas pressure applications.
• NHB boilers can be installed on 1/2" gas lines for up to 24'
Cascade multiple units in parallel for larger applications. Everything is included in the box.
NHB-55 boilers that ship from GadgetsGo are the latest version, which have Navien's Ready-Link cascading system.
• Built-in controls for easily configuring the settings for a multi-unit, cascading system.
• No extra control boards are required, so your installation cost are lower.
• Easily wire together units and set one boiler as parent and one as child.
• Up to 16 units can be linked in one group. Unlimited groups can be cascaded. Cascading creates redundancy to ensure hot water availability.
• NHB-series boilers can be installed on a wall, and have a compact, small form factor. This allows for a multi-unit installation in a smaller area.
• Popular applications: Hotels, restaurants, schools, hospitals, health centers, beauty shops, and more.
|Max BTU per hour input
||24in. (H) x 17in. (W) x 12in. (D)
||73 lb (33 kg)
||Forced Draft Direct Vent
|Natural Gas Supply Pressure (from source)
||3.5 in.–10.5 in. WC
|Propane Gas Supply Pressure (from source)
||8.0 in.–13.5 in. WC
|Natural Gas Manifold Pressure
||-0.03 in. WC
|Propane Gas Manifold Pressure
||-0.03 in. WC
|Gas Connection Size
||3/4 in. NPT (female)
|Space Heating Water Supply and Return Connection Sizes
||1 in. NPT
|Main Power Supply
||120V AC, 60Hz
|Maximum Power Consumption
||Less than 10A
||Cold-rolled carbon steel
||Primary and Secondary: Stainless Steel
||2 in. or 3 in. PVC, CPVC, approved polypropylene* 2 in. or 3 in. Special Gas Vent Type BH (Class III, A/B/C)
||2 in. or 3 in. PVC, CPVC, polypropylene 2 in. or 3 in. Special Gas Vent Type BH (Class III, A/B/C)
||0 in. to combustibles
||Flame Rod, APS, Gas Valve Operation Detector, Ignition Operation Detector Water Temperature High Limit Switch, Exhaust Temperature High Limit Sensor
|Maximum Altitude Operation
||10,100 feet with appropriate dip switch settings
Installation & Operation Manual
User's Information Manual
Quick Installation Manual
Wall Mounting Bracket
Four Tapping Screws & Anchors
LP or NG Conversion Kit
Two 2" Vent Termination Caps
Four 2" Wall Flanges
Pressure Relief Valve for Heating
Outdoor Temperature Sensor and Cable
Air Vent Bushing (3/4" to 1/2")
Spare Parts (fuse, etc.)
• Quick Installation Guide
• Energy Guide Label
• User's Information Manual
• Operation & Installation
• Gas Conversion Guide
Navien old item number: NHB-055. Alternate model number spelling: NHB55
Frequently Asked Question ("FAQ")
Q: Which thermostat(s) will work with this unit?
A: Any thermostat that does not have a common wire will work with Navien NHB units.
Installation Help and Recommendations
We recommend that you have a professional tankless water heater installer review the above recommendations. Need an installer? Get 4 FREE Tankless Water Heater Installation Estimates Now. It's Quick and Easy!
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Consumer purchases through the internet or other e-commerce channels shall void Navien's warranty. As with all products we sell, all Navien products we sell are brand new, recently manufactured ("factory fresh"). We guarantee delivery in perfect condition to our customers.
The NAVIEN, KD NAVIEN, ComfortFlow, Ready-Link, and NaviLink trademarks are the property of Navien America, Inc. and/or KyungDong Navien. Navien is not affiliated with and does not sponsor, endorse or warranty/support GadgetsGo.com or products on this website.