The first high efficiency tankless
condensing combi‑boiler that can do it all

NCB-E Applications

  • Air handler
  • Hydronic heating
  • Hydronic fan coil
  • Baseboard radiator
  • Radiant floor

For NCB-E technical drawings of specific installations and requirements, please visit Navien.com

Space saving design occupies 80% less space than a traditional floor standing boiler and tank water heater.



NCB-E: the inside story

Manifold Kits

For fast installation and maximum efficiency, install our system matched manifold kits

Compare these advantages to any tankless condensing combi system

Dual inputs of up to 120k BTU/h for heating and 199k BTU/h for DHW

Supplies all the heat and domestic hot water that most houses require.

PVC venting

Low exhaust gas temperatures allows use of PVC, CPVC, ULC S636 and polypropylene vent systems, reducing installation time and costs. System can use 2″ venting for up to 60′, or up to 150′ with 3″ venting.

4.5 GPM@77° temperature rise for domestic hot water

Separate stainless steel flat plate heat exchanger for DHW creates the highest flow rate for any combi‑boiler in the industry.

Uses existing ½” gas piping

Save time and effort in retrofit applications with ½” gas lines for up to 24′.

Turn down ratio of 6:1 for heating and 11:1 for DHW

The sophisticated gas flow control system provides a high turn down ratio, reducing energy waste and excessive boiler cycling and enhances temperature control for DHW.

Low gas pressure operation

Operates at minimum gas pressure of 3.5 inches of water column. Allows for easy conversion from natural gas to LP.

Dual stainless steel heat exchangers 

Stainless steel heat exchangers for hydronic heating are warranted for 10 years. They resist corrosion longer than copper or aluminum heat exchangers.

Space saving design

Occupies 80% less space than a traditional floor standing boiler and tank water heater.

Field gas convertibility

Dual venturi system allows for easy field convertibility from NG to LP operation. Orifice for LP conversion included.


For extraordinarily large domestic hot water flow demand, the NCB-E can be cascaded with an NPE unit.