Download the new Navien mobile app!

Apple iOSGoogle Android

NFC-250/175H

high efficiency Condensing Combi-Boiler

NFC‑H
NFC-250/175H certifications

NFC-250/175H

high efficiency Condensing Combi-Boiler

  • 95% AFUE – Energy Star certified
  • DHW 15:1 TDR and heating 13:1 TDR
  • 2” venting up to 65’, 3” venting up to 150'
  • Advanced controls with intuitive user interface and Setup Wizard
  • NEW DHW module with mixing and water adjustment valves
  • Built-in powered connections for 3 zone valves or 3 zone pumps
  • Common venting with up to 7 NPE units and cascading up to 15 NPE units
  • Approved for high altitude up to 10,100 ft. (NG and LP), conversion kits included
  • Patented stainless steel fire tube heat exchanger with non-metallic condensate base
Credits & Rebates Finder
Find Sales Rep

NFC-250/175H premium features and benefits


2" venting up to 65' (including schedule 40 PVC). Vent Installation Detector (VID) for added safety.


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


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


Advanced user interface with Setup Wizard is made easy with backlit panel, click-wheel control and intuitive text.


Advanced user interface with Setup Wizard is made easy with backlit panel, click-wheel control and intuitive text.


Advanced circuitry with built-in control for 3-zone pumps or 3-zone valves.


Easily accessible built-in DHW module includes integrated boiler pump, flow adjustment valve, DHW stainless steel heat exchanger, mixing valve and 3-way valve.

 

1/2" gas pipe capability up to 24' (subject to local codes). Cuts installation time, no need to install new gas lines for retrofit applications.

NFC-250/175H QuickFacts

NFC‑H Videos

NFC-250/175H FAQs

A combi (combination) boiler is designed to heat a building, using hot water (similar to a boiler), but also includes the components and controls to internally heat the domestic hot water (DHW) required in the application. By having both heating and hot water in one unit, the combi will save space in the mechanical room and also save on the initial installation compared to separate appliances.

A combi (combination) boiler provides both space heating and on demand domestic hot water. In heating mode, water from the space heating system will flow through the heat exchanger and out to the system similar to a standard boiler. When a domestic hot water demand (open faucet) occurs, water flows through a separate heat exchanger in the combi, and a valve inside the unit diverts heating water over to the DHW heat exchanger. Space heating water is used to heat the domestic hot water until the demand ends. At the end of the domestic demand, the combi will switch back to supply space heating.

Inside the combi-boiler is a heat exchanger that separates the space heating flow from the domestic water flow, so the water in the heating system is isolated from the domestic hot water. The only thing that happens in the heat exchanger is that the heat from the higher temperature space heating water is transferred to the lower temperature domestic water.

Since the combi boiler provides both space heating and domestic hot water all in one unit, it can provide space savings over two or more units. Combi boilers also can provide endless hot water in DHW mode, similar to a tankless water heater. Combi boilers may also reduce the installation cost by reducing the number of appliances, possibly reducing the number of wall or roof penetrations required for exhaust and intake piping, and may reduce some of the gas piping requirements.

Combi-boilers do not require any additional requirements, compared to a condensing boiler and water heater. Compared to installing two different appliances, the installation may even have fewer requirements.

When a DHW (hot water) demand happens in a Navien combi boiler, the unit switches from space heating mode over to DHW mode. Referred to as DHW Priority, the unit will utilize the full capacity to heat the domestic hot water until the flow stops, providing endless hot water. While in DHW priority mode, the space heating is disabled. Even with a long shower or extended DHW run time, the home may lose a few degrees, but the chances of the home freezing during that time are extremely low.

The heating size of the boiler is determined by calculating the heat loss of the building, which is based on the size of the structure, the insulation value of the surfaces, and the door and window sizes. Since combi boilers also provide domestic hot water, the flow demand of the hot water fixtures also needs to be calculated to determine the maximum DHW flow required. A combi boiler size is chosen by ensuring that the unit can satisfy both demands. Typically with a combi boiler, the BTU input will be higher for the DHW demand than for the heating load. A qualified contractor can perform a heat loss and help recommend a proper boiler size.

Please see the following attachment on where you can locate your serial number.

1. Locating Serial Number

The applicable period for this labor allowance for all water heater models is One (1) year from the effective date.

The payment and amount of any payment are subject to approval at Navien’s sole discretion.

The labor allowance will be paid based on Navien’s schedule of labor allowances.

Because our product involves water, electricity, and gas, there is only a limited amount of troubleshooting that can be done with a homeowner/end-user.

We recommend contacting your original installer or a Navien Service Specialist (NSS) to troubleshoot the unit.

NOTE: Charges will apply for service calls outside of 1 year labor period and/or non-warranty issues. Please see terms of our labor warranty.

Because our product involves water, electricity, and gas, there is only a limited amount of troubleshooting that can be done with a homeowner/end-user. We recommend contacting your original installer or a Navien Service Specialist (NSS) to troubleshoot the unit. NOTE: Charges will apply for service calls outside of 1 year labor period and/or non-warranty issues. Please see terms of our labor warranty.

If you feel like there is an issue with your unit, please have someone contact Navien Technical Support while in front of the unit with your Serial Number ready. We recommend that a license contractor, original installer, or NSS contact is the person who calls us, so we may do in depth troubleshooting to determine if there is a part failure.

Navien Technical Support will be unable to send out parts without registration of product (Serial Number, Date of Installation, Homeowner Information, and Installer Information).

Compare NFC‑H models

NFC-250/175H
Max HTG Input: 175,000 BTU/h
Max DHW Input: 210,000 BTU/h
Indoor wall-hung
Residential/Commercial
NFC-250/175H
View model
NFC-250/175H
NFC-250/200H
Max HTG Input: 199,900 BTU/h
Max DHW Input: 210,000 BTU/h
Indoor wall-hung
Residential/Commercial
NFC-250/200H
View model
NFC-250/200H
Contact Us