• Field convertible gas system
  • Ultra condensing efficiency
  • Dual stainless steel heat exchangers
  • Low NOx emissions (20ppm)
  • SCH 40, 2″ venting up to 75′
  • Cascading capable
  • EZNav multi-line control panel
  • Built-in HotButton control panel
  • Common vent up to 12 units

NPE-150S2 premium features and benefits

2″ PVC venting up to 75 feet
Low exhaust gas temperatures allow use of PVC (including schedule 40 PVC), CPVC, polypropylene (rigid and flexible) and stainless steel venting saving time and costs.Vent Installation Detector (VID) for added safety.

Dual Venturi for field gas conversions. Dual Venturi system creates better combustion control and turndown ratio.

ComfortFlow® NPE-A2 built-in recirculation system
The patented ComfortFlow® system is the first to include a buffer tank, recirculation pump and fine-tuned controls into a tankless water heater.

Dual stainless steel heat exchangers for added durability.

EZNav™ Multi-line control with built-in intuitive software.


Heat Capacity (input)Natural gas18,000 – 120,000 BTU/h
Propane18,000 – 120,000 BTU/h
Efficiency ratingsUEF (NG & LP)0.93
Flow rate (DHW)19°C temp rise25.7 l/m (6.8 GPM)
25°C temp rise20.1 l/m (5.3 GPM)
37°C temp rise12.9 l/m (3.4 GPM)
Dimensions43.9cm W x 69.6cm H x 33.5cm D (17.3″ W x 27.4″ H x 13.2″ D)
Boiler weight28.1 kg (62 lbs)
Installation typeIndoor or outdoor wall-hung
Venting typeForced draft direct-vent
IgnitionElectronic ignition
Water pressure1.055-10.545 kg/cm2 (15-150 PSI)
Natural gas supply pressure (from source)3.5 ” WC to 10.5 ” WC
Propane gas supply pressure (from source)8 ” WC to 13 ” WC
Natural gas manifold pressure (min-max)-0.04 ” WC to -0.4 ” WC
Propane gas manifold pressure (min-max)-0.03 ” WC to -0.4 ” WC
Minimum flow rate1.893 l/m (0.5 GPM)
Connection sizesCold water inlet3/4″ NPT
Hot water outlet size3/4″ NPT
Gas inlet3/4″ NPT
Power supplyMain supply120V AC, 60 Hz
Maximum power consumption200 W (max 2 A), 350 W (max 4 A) with external pump connected
MaterialsCasingCold rolled carbon steel
Heat exchangersPrimary heat exchanger: stainless steel Secondary heat exchanger: stainless steel
VentingExhaust2″ or 3″ PVC, CPVC, approved polypropylene and stainless steel 2″ or 3″ special gas vent type BH (Class II, A /B/C)
Intake2″ or 3″ PVC, CPVC, approved polypropylene and stainless steel 2″ or 3″ special gas vent type BH (Class II, A /B/C)
Vent clearances0″ to combustibles
High elevations10,100 feet for both NG or LP gas. Please refer to Installation Manual for additional details and instructions.
Safety DevicesFlame rod, APS, ignition operation detector, water temperature high limit switch, exhaust temperature high limit sensor, power surge fuse, burner high limit fuse, vent installation detector (VID)

*Available for NPE-A2 models configured in an optional ComfortFlow® recirculation mode. Energy consumption will increase when the system is configured for recirculation.

Navien reserves the right to change specifications at any time without prior notice.


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