Navien NHB-H Series Condensing Boiler | Ultra-High Efficiency
The Navien NHB-H Series Condensing Boilers is an ultra-high-efficiency, wall-hung condensing heating boiler available in four sizes from 55,000 to 150,000 BTU/h maximum input. With 95% AFUE, stainless steel heat exchangers, built-in zoning controls, and flexible direct-vent options, the NHB-H is designed for efficient hydronic heating applications.
The series is available for natural gas and can be converted to propane using the applicable conversion kit. Proper boiler selection requires a heat-loss calculation and consideration of the existing hydronic system.
Navien NFC-H Combi-Boiler (NFC-250/175H & NFC-250/200H) – Supplied & Professionally Installed by 4Most Energy
The Navien NFC-H is a high-capacity condensing fire tube combi-boiler that provides hydronic space heating and domestic hot water from one compact wall-hung unit. It is available in two sizes: the NFC-250/175H (heating input 13,300 to 175,000 BTU/h) and the NFC-250/200H (heating input 13,300 to 199,900 BTU/h). Both models have a domestic hot-water input of 13,300 to 210,000 BTU/h and are rated at 95.0% AFUE.
Navien's patented stainless steel fire tube heat exchanger is ASME-certified and H-stamped, while a separate stainless steel flat-plate heat exchanger supplies domestic hot water – up to 5.4 GPM at a 70°F temperature rise, enough for up to 3 showers and a dishwasher at the same time. The fully modulating metal-fiber premix burner gives a turndown ratio of up to 15:1, and the integrated boiler pump and built-in controls for up to three zone pumps or three zone valves simplify installation and zoning.
Proper installation requires attention to gas supply, venting, condensate drainage, electrical supply, hydronic and domestic water connections. The brochure specifies 2″ venting up to 65 feet and 3″ venting up to 150 feet. The unit uses a 120V AC, 60Hz supply, has a 3/4″ NPT gas connection, and can use existing 1/2″ gas piping up to 24 feet where local code allows.
Correct sizing is essential. The heating side should be sized from the home's heat-loss calculation, and domestic hot-water demand should be evaluated separately. 4Most Energy can assess the existing system and recommend the right NFC-H model.
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Why Install the Navien NFC-H with 4Most Energy?
- 95.0% AFUE condensing efficiency – ENERGY STAR certified.
- Two sizes: NFC-250/175H (175,000 BTU/h heating) and NFC-250/200H (199,900 BTU/h heating).
- 210,000 BTU/h maximum DHW input on both models.
- Up to 5.4 GPM DHW flow at a 70°F temperature rise.
- Turndown ratio up to 15:1 for heating and DHW (heating 15:1 on NFC-250/200H).
- Patented stainless steel fire tube heat exchanger plus a separate stainless steel flat-plate DHW heat exchanger.
- Integrated boiler pump – no external pump needed for heating and DHW.
- Built-in powered controls for up to three zone pumps or three zone valves.
- 2″ PVC venting up to 65 ft, 3″ up to 150 ft; natural gas or propane (conversion kits included).
- Advanced user interface with setup wizard; optional NaviLink Wi-Fi control.
| Specification | NFC-250/175H | NFC-250/200H |
|---|---|---|
| Model | NFC-250/175H | NFC-250/200H |
| Product Type | Condensing combination boiler | Condensing combination boiler |
| Heating Input | 13,300–175,000 BTU/h | 13,300–199,900 BTU/h |
| Heating Capacity | 161,000 BTU/h | 183,000 BTU/h |
| Net AHRI Rating – Water | 140,000 BTU/h | 159,000 BTU/h |
| DHW Input | 13,300–210,000 BTU/h | 13,300–210,000 BTU/h |
| Efficiency | 95.0% AFUE | 95.0% AFUE |
| Fuel Type | Natural Gas / Propane convertible | Natural Gas / Propane convertible |
| Installation Type | Indoor wall-hung | Indoor wall-hung |
| Venting Type | Forced-draft direct vent | Forced-draft direct vent |
| Venting Options | 2″ or 3″ PVC, CPVC, approved polypropylene, special gas vent or stainless steel | 2″ or 3″ PVC, CPVC, approved polypropylene, special gas vent or stainless steel |
| Venting Length | 2″ up to 65 ft · 3″ up to 150 ft | 2″ up to 65 ft · 3″ up to 150 ft |
| Gas Connection | 3/4″ NPT | 3/4″ NPT |
| Natural Gas Supply Pressure | 3.5″–10.5″ WC | 3.5″–10.5″ WC |
| Propane Supply Pressure | 8.0″–13.5″ WC | 8.0″–13.5″ WC |
| Electrical | 120V AC, 60Hz | 120V AC, 60Hz |
| Maximum Power Consumption | Less than 15 amperes | Less than 15 amperes |
| Heating Supply/Return | 1″ NPT | 1″ NPT |
| DHW Supply/Return | 3/4″ NPT | 3/4″ NPT |
| Water Pressure – Heating | 12–80 PSI | 12–80 PSI |
| DHW Water Pressure | 15–150 PSI | 15–150 PSI |
| DHW Minimum Flow | 0.5 GPM | 0.5 GPM |
| DHW Flow @ 45°F Rise | 7.9 GPM | 7.9 GPM |
| DHW Flow @ 70°F Rise | 5.4 GPM | 5.4 GPM |
| Space Heating Supply Temp. Range | 77–185°F | 77–185°F |
| DHW Temperature Range | 86–140°F | 86–140°F |
| Dimensions | 17.3″W × 17.3″D × 33.5″H | 17.3″W × 17.3″D × 33.5″H |
| Boiler Weight | 141 lb | 141 lb |
| Weight with Water | 170 lb | 170 lb |
| Boiler Water Volume | 4.5 gallons | 4.5 gallons |
| Heat Exchanger Material | Stainless steel | Stainless steel |
| Casing | Cold-rolled carbon steel | Cold-rolled carbon steel |
| Ignition | Electronic ignition | Electronic ignition |
| Vent Clearance | 0″ to combustibles | 0″ to combustibles |
| Model | Heating Input | DHW Input | Heating Capacity | Recommended Home Size | Recommended Occupants |
|---|---|---|---|---|---|
| NFC-250/175H | 13,300–175,000 BTU/h | 13,300–210,000 BTU/h | 161,000 BTU/h (net AHRI 140,000) | Must be determined by heat-loss calculation | Must be determined from DHW demand |
| NFC-250/200H | 13,300–199,900 BTU/h | 13,300–210,000 BTU/h | 183,000 BTU/h (net AHRI 159,000) | Must be determined by heat-loss calculation | Must be determined from DHW demand |
The Navien NFC-H is built for larger homes that need both high-capacity hydronic heating and high domestic hot-water demand from one wall-hung unit. Choose the model by the heating load, not by square footage alone.
- NFC-250/175H heating capacity: 161,000 BTU/h (net AHRI 140,000 BTU/h)
- NFC-250/200H heating capacity: 183,000 BTU/h (net AHRI 159,000 BTU/h)
- Both models: 210,000 BTU/h DHW input, up to 5.4 GPM at 70°F rise
Ideal for multiple hydronic heating zones, including in-floor radiant loops, radiators, baseboards and air-handler systems. For more hot water, the NFC-H can be cascaded with up to 15 Navien NPE-2 tankless water heaters.
⚙️ Your installer confirms the right size with a heat-loss calculation and a hot-water demand review before installation.
Best Fit ( Size & Applications )
NFC-250/175H: large homes with high hot-water demand and multi-zone heating.
NFC-250/200H: larger heat loads – Navien’s highest-capacity residential combi-boiler.
Supports up to 3 showers and a dishwasher at the same time (5.4 GPM at 70°F rise).
Excellent for multi-zone radiant heating, radiators, air handlers and mixed hydronic systems.
1. Request Installation Quote Provide information about your existing heating and hot-water system so the installation requirements can be reviewed.
2. System Sizing Consultation Heating requirements and domestic hot-water demand are evaluated to choose between the NFC-250/175H and NFC-250/200H.
3. Equipment Recommendation 4Most Energy confirms the equipment configuration, installation requirements, venting approach, gas requirements and system connections.
4. Installation Scheduling Once the project scope and quotation are approved, an installation date is arranged.
5. Removal of Existing Equipment Where applicable, the existing boiler, water heater and associated equipment are removed as included in the approved installation scope.
6. Installation & System Connection The NFC-H is wall-mounted and connected to the heating supply and return, domestic hot-water lines, gas, electrical supply, venting, combustion air and condensate drainage as required.
7. Safety Testing The installation is checked for proper operation, combustion, water pressure, gas connections, venting and safety controls.
8. Final Commissioning The system is configured with the setup wizard and tested to verify heating and domestic hot-water operation.
The Navien NFC-H Series warranty, as stated in the manufacturer’s 2025 brochure, provides different coverage for residential and commercial installations. For single-family residential locations, the heat exchanger is covered for 10 years, parts for 5 years, and labor for 1 year. Commercial installations receive 5 years of heat exchanger coverage, 3 years for parts, and 1 year for labor.
| Warranty Coverage | Residential* | Commercial |
|---|---|---|
| Heat Exchanger | 10 Years | 5 Years |
| Parts | 5 Years | 3 Years |
| Labor | 1 Year | 1 Year |
*Residential warranty applies to single-family residential locations. For complete warranty details, please refer to Navien's full warranty documentation.
Warranty Claim Process
For warranty service, 4Most Energy can assist with identifying the issue and coordinating the appropriate service process. Warranty eligibility and coverage are subject to Navien’s full warranty terms and conditions.
Optional Maintenance Plan
Maintenance plans starting from $12.99/month
A maintenance plan can help keep the combi-boiler operating properly through scheduled professional service and system checks. Enrollment is optional and can be discussed with 4Most Energy.
Service Area
Greater Toronto Area (GTA) and surrounding regions
Toronto, Markham, Richmond Hill, Vaughan, Aurora, Newmarket, Scarborough, Brampton, and Mississauga.
Extended Service Area: Stouffville, Oshawa, Barrie, Orangeville, Hamilton, St. Catharines, Guelph, Kitchener.
Navien Boiler FAQs
Answered by 4Most Energy Experts
What is the difference between the NFC-250/175H and NFC-250/200H?
Both are condensing combi-boilers with 95.0% AFUE and the same 210,000 BTU/h DHW input. The NFC-250/175H has a heating input of 13,300–175,000 BTU/h (161,000 BTU/h heating capacity). The NFC-250/200H has 13,300–199,900 BTU/h heating input (183,000 BTU/h heating capacity) for larger heat loads.
Is the Navien NFC-H a combi-boiler?
Yes. The NFC-H is a high-capacity condensing combi-boiler that provides hydronic space heating and domestic hot water from one wall-hung system. It uses a stainless steel fire tube heat exchanger for heating and a separate stainless steel flat-plate heat exchanger for hot water.
How much hot water can the NFC-H produce?
Both models have a maximum DHW input of 210,000 BTU/h. Hot-water flow reaches 5.4 GPM at a 70°F temperature rise and 7.9 GPM at a 45°F rise, depending on installation conditions.
Can the NFC-H heat my whole house and provide hot water at the same time?
Yes. The NFC-H is designed to provide space heating and domestic hot water from one system, with separate heat exchangers for each function and an integrated boiler pump.
Which size do I need?
Square footage alone should not be used to size the boiler. The right model depends on the home’s heat loss, heating zones, insulation, windows, existing hydronic system and hot-water demand. 4Most Energy can evaluate your home and recommend the right capacity.
Can the NFC-H work with multiple heating zones?
Yes. It has built-in controls for up to three zone pumps or three zone valves. The control board supplies 120VAC for zone pumps and 24VAC for zone valves. A SmartZone+ controller can expand zoning to 4–6 zone pumps.
Does the NFC-H use a stainless steel heat exchanger?
Yes. Navien’s patented stainless steel fire tube heat exchanger is ASME-certified, H-stamped and built with automated laser welding. The DHW side uses a separate stainless steel flat-plate heat exchanger.
Can the NFC-H be converted from natural gas to propane?
Yes. The NFC-H is field gas convertible between natural gas and propane using the dual Venturi system and included orifice kits, including high-altitude applications up to 10,100 feet. Conversion must follow Navien’s procedures.
What type of venting does the NFC-H require?
It is an indoor wall-hung, forced-draft direct-vent appliance. Venting can be 2″ or 3″ PVC, CPVC, polypropylene, special gas vent or stainless steel: 2″ up to 65 feet or 3″ up to 150 feet.
How long is the Navien NFC-H warranty?
For single-family residential locations the brochure lists a 10-year heat exchanger, 5-year parts and 1-year labor warranty. Commercial: 5-year heat exchanger, 3-year parts, 1-year labor.
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