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The Navien NCB-E combi-boiler is one of a kind. It is the first high-efficiency combi-boiler with the capacity to supply heat and domestic water for larger homes, enough hydronic heat for the entire house, while also providing the hot water to run two showers and a dishwasher simultaneously. The Navien NCB-E does it all.


Sleek design saves spaces
Takes up 80% less space than a traditional floor standing boiler and storage tankLinkability feature
For extremely high hot water flow demand, the NCB-E can be cascaded with other units

Dual inputs of up to 120k BTU/H for heating and 199k BTU/H for DHW
Will supply enough heat and domestic water for most house requirements

4.5 GMP at 77 degree temperature rise for domestic hot water
With a separate stainless steel flat plate heat exchanger for DHW, this creates the highest flow rate for any combi-boiler in the industry

Turn Down ratio of 6:1 for heating and 11:1 for DHW
The advanced gas flow control system provides a high turn down ratio, reducing wasted energy and unnecessary boiler cycling, all while enhancing temperature control for DWH

Dual stainless steel heat exchangers
Fights on the onset of corrosion better than copper to provide a longer lasting comfort

Field gas conversion
The Dual venturi system allows for easy field conversion from NG to LP. The orifice for LP conversion is included as well

PVC venting
Low exhaust temperatures allows for the use of PVC, CPVC, ULC S636 and polypropylene vent systems. This reduces installation time and increases efficiency. The system is capable of using 2” venting for up to 60 feet, or up to 150 feet with 3” venting

Low gas pressure
The negative pressure gas valve ensures peak performance even in a minimum gas pressure of 3.5” of water column

Ability to use existing 1/2″ gas piping
Save time and effort in retrofitting applications with ½” gas lines for up to 24 feet

It’s what’s inside that counts
interior combi boiler
  • Features a pressure relief valve
  • 2″ PVC schedule 40 capable up to 60′
  • 2″ PVC air intake venting
  • Dual Venturi for easy field conversion
  • Stainless steel heat exchanger
  • 2″ PVC air intake venting
  • Powder-coated enamel metal housing shell
  • Secondary stainless steel heat exchanger
  • Integrated control panel
  • Negative pressure gas valve
  • Stainless steel flat plate heat exchanger for domestic hot water
  • Integrated boiler pump
  • Negative pressure gas valve
  • Heating system auto fill
  • Domestic hot water inlet
  • Primary heating loop supply
  • Primary heating loop return
  • 1/2″ gas pipe capable up to 24′

NavilLink can be easily connected in order to communicate with your Navien systems anywhere that internet service is available. The NaviLink module is easily attached to any new or existing Navien tankless water heater, combi-boiler and boiler.


Available in four sizes

Heating BTU/H
NCB-150E 12,000-60,000 12,000-120,000
NCB-180/NCB-180E 14,000-80,000 14,000-150,000
NCB-210/NCB-210E 18,000-100,000 18,000-180,000
NCB-240/NCB-240E 18,000-120,000 18,000-199,900


  • Air handler/Hydronic Heating
  • Hydronic coils
  • Baseboard radiators
  • Radiant floors


Gas Input Space heating 18,000 – 120,000 (BTU/H)
Domestic hot water 18,000 – 199,900 (BTU/H)
Flow rate (DHW) 77°F (43°C) temp rise 4.5 GPM (17.0 L/m)
Dimensions 17.0″ W x 28.0″ H x 12.0″ D
Weight 84.0lbs (38kg)
Installation Type Indoor wall-hung
Venting Type Forced draft direct vent
Ignition Electronic ignition
Hydronic water pressure 12.0-30.0 PSI
DHW water pressure 15.0-150.0 PSI
Natural gas supply pressure (from source) 3.5″ WC – 10.5″ WC
Propane gas supply pressure (from source) 8″ WC – 13″ WC
Natural gas manifold pressure (min-max) -0.06″ WC – -1.2″ WC
Propane gas manifold pressure (min-max) -0.03″ WC – -0.98″ 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 (max 2A)
Materials Casing Cold rolled carbon steel
Heat exchanger 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, ignition operation detector, water temperature high limit switch, exhaust temperature high limit sensor, power surge fuse

Navien Combination Boiler Space Heating Ratings

Model 1
Heating Input, MBH Min 18
Max 120
Heating Capacity2, MBH 112
Net AHRI Rating, Water3, MBH 97
AFUE2, % 95

Other Specifications

Water Pressure 12.0-30.0 PSI

Combi Boiler Repair

Royal Oak, MD

Hurlock, MD

Woolford, MD

Trappe, MD

Federalsburg, MD

Saint Michaels, MD

Centreville, MD

Queenstown, MD

Newcomb, MD

Cordova, MD

Stevensville, MD

Denton, MD

Kent Island, MD