Condensing Gas Combination Boiler – NCB-150E

Max Input : 120,000 BTU/H
Indoor Only
Residential Only

  • Super condensing efficiency
  • Dual stainless steel heat exchangers
  • SCH40, 2” PVC venting up to 60’
  • ½” Gas pipe up to 24’
  • Automatic water filling system
  • integrated controls


Ultra Condensing Efficiency

  • Navien’s Condensing Technology offers the high efficiency.
  • Money and energy savings over tank type water heaters and traditional water heaters.

Two Stainless Steel Heat Exchangers

  • Provides longer life expectancy as they are highly resistant to corrosion and erosion compared to copper heat exchangers.
  • Reduces minerals deposits.

Low NOx Emissions (≤ 20ppm)

  • New metal fiber burner is designed to deliver a consistent air/gas mixture improving combustion efficiency.
  • Result in less acid rain and less green house effect.
  • Comply with SCAQMD 1146.2 strict NOx emissions standard.

2” PVC, CPVC, Polyprophylene Venting Up To 60’

  • 2” venting option allows for a flue to be pulled through the existing vent.
  • 3” vents can be used up to 150’ with standard 2” x 3” adapters.

Utilizes Existing 1/2″ Gas Line

  • The negative pressure gas valve and fan with dual venturi operation allows for better adaptability to low gas pressure applications.
  • Makes it possible for the NPE to be installed ½” gas lines up to 24’.

Field Convertible

  • NCB models allow for easy convertibility from NG to LP.

Where Technology Meets Ecology, Combination Boiler

  • The ideal solution for customers who need both domestic hot water and a space heating application.
  • Heats water when needed, making it environmentally sound as well as cost efficient.

Hydronic Heating Benefits

  • Clean: little chance to cause dust or lower humidity because there is no air movement.
  • Silent: offers silent heating because no blowers are needed for forced circulation.
  • Comfort: keeps floors warm but indoor air fresh, making people feel warm and comfortable.
  • Coverage: radiant heat makes heating from floor to ceiling possible.
  • Economical: radiant heat in the floors can transmit warmth throughout the house hours after turning off the heater.

Automatic Water Filling System

  • Automatically fills water into space heating pipes when the unit senses a water shortage.

Powerful Anti-Freeze Feature

  • The Combi’s built-in Control System is designed to keep the unit’s plumbing frost free in winter conditions.


Data Field NCB-150E
Gas Input Space Heating 12,000–60,000 BTU/H
Domestic Hot Water 12,000–120,000 BTU/H
AFUE 95.0%
Flow Rate (DHW) 77°F (43°C) Temp Rise 2.6 GPM (9.8 L/m)
Dimensions 17″(W) x 28″(H) x 12″(D)
Weight 66 lbs (30kg)
Installation Type Indoor wall-hung
Venting Type Forced draft direct vent
Ignition Electronic ignition
Water Pressure (Hydronic/DHW) 12–30 PSI /15–150 PSI
Natural Gas Supply Pressure (from source) 3.5″ –10.5″ WC
Propane Gas Supply Pressure (from source) 8.0″ –13.5″ WC
Natural Gas Manifold Pressure (min to max) -0.08″ WC / -0.34″ WC
Propane Gas Manifold Pressure (min to max) -0.08″ WC / -0.30″ WC
Minimum Flow Rate (DHW) 0.5 GPM (1.9 L/m)
Connection Sizes Heating Supply/Return 1″ NPT
DHW Inlet/Outlet 3/4″ NPT
Gas Inlet 3/4″ NPT
Auto Feeder 1/2″ NPT
Condensate Outlet 1/2″ NPT
Power Supply Main Supply 120V AC, 60Hz
Maximum Power Consumption 200W (up to 2 amperes)
Materials Casing Cold rolled carbon steel
Heat Exchangers Primary/secondary heat exchanger: stainless steel DHW heat exchanger: stainless steel
Venting Exhaust 2″ or 3″ PVC, CPVC, approved polypropylene 2″ or 3″ special gas vent type BH (Class II, A/B/C)
Intake 2″ or 3″ PVC, CPVC, polypropylene 2″ or 3″ special gas vent type BH (Class II, A/B/C)
Vent Clearances 0″ to combustibles
Safety Devices Flame rod, APS, gas valve operation detector, ignition operation detector, water temperature high limit switch, exhaust temperature high limit sensor

Spec Sheet