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  • 97.5% TE Industry Leading Thermal Efficiency
  • Patented stainless steel fire tube heat exchanger
  • 160 PSI maximum operating pressure
  • Advanced controls with intuitive 7” color display
  • Up to 15:1 TDR (turndown ratio)
  • BAS communication capability
  • Common vent up to 4 and cascade up to 32 units
  • Top & bottom piping

NFB-301C premium features and benefits

Multiple venting options. Low exhaust gas temperatures allow use of PVC, CPVC, polypropylene (rigid and flexible) and stainless-steel venting reducing installation time and costs.

Patented stainless steel fire tube heat exchangerNavien’s innovative heat exchanger design is ASME‑Certified,“H” Stamped, and reduces high-stress point weld failures common on other combi-boilers.

Dual Venturi and field gas convertibility. Dual Venturi system creates better combustion control and turndown ratio. Orifice for easy field gas convertibility from NG to LP. Conversion kits included.

Top and bottom piping
Easy pipe connections for floor or wall-hung installations.

Low gas pressure operation. Negative pressure regulating gas valve ensures maximum performance all the way down to 3.5″ of water column on natural gas and 8″ of water column on propane gas.

Built-in hardware connects boiler pump & 3 zone pumps. All integrated into the NFB-C circuit board. Also includes a DHW priority zone

Advanced 7″ touch screen controls Easy intuitive navigation for setup, troubleshooting and operation.Built-in USB port
Download boiler data and settings. Upload software updates and boiler settings.


Water volume28.8 l (7.6 gal)
Dimensions63.8cm W x 83.3cm H x 56.6cm D (25.1″ W x 32.8″ H x 22.3″ D)
Boiler weight110.2 kg (243 lbs)
Boiler Weight With Water139.3 kg (307 lbs)
Installation typeIndoor wall-hung
Venting typeForced draft direct vent and non-direct vent (single pipe)`
IgnitionElectronic ignition
Natural gas supply pressure (from source)3.5 ” WC to 10.5 ” WC
Propane gas supply pressure (from source)8 ” WC to 13.5 ” WC
Natural gas manifold pressure (min-max)-0.06 ” WC to -0.87 ” WC
Propane gas manifold pressure (min-max)-0.01 ” WC to -0.92 ” WC
Connection sizesGas inlet3/4″ NPT
Power supplyMain supply120V AC, 60Hz
Maximum power consumptionLess than 12 amperes
MaterialsCasingCold rolled carbon steel
Heat exchangersStainless steel
VentingExhaust3″ or 4″ PVC, CPVC, PP and SS / 3″ or 4″ special gas vent type BH (Class III, A/B/C
Intake3″ or 4″ PVC, CPVC, PP and SS / 3″ or 4″ special gas vent type BH, (Class III, A/B/C)
Vent clearances0″ to combustibles
Safety DevicesFlame rod, APS, Ignition operation detector, Water temperature high limit switch, Exhaust temperature high limit sensor, Water pressure sensor
Navien reserves the right to change specifications at any time without prior notice.


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