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 NFB-H Heat-Only Boiler (NFB-175H & NFB-200H) – Supplied & Professionally Installed by 4Most Energy
The Navien NFB-H is a high-capacity, heat-only condensing fire tube boiler in a compact wall-hung cabinet. It is available in two sizes: the NFB-175H (heating input 13,300 to 175,000 BTU/h) and the NFB-200H (heating input 13,300 to 199,900 BTU/h). Both models are rated at 95.0% AFUE and are ENERGY STAR certified. Navien's patented stainless steel fire tube heat exchanger is ASME-certified, H-stamped and built with robotic laser welding for durability and efficient heat transfer.
The NFB-H uses a fully modulating metal-fiber premix burner with a dual Venturi system, giving a turndown ratio of 13.2:1 (NFB-175H) or 15:1 (NFB-200H). This lets the boiler match its output to the heating load instead of cycling on and off at full fire. Built-in powered connections for up to three zone pumps or three zone valves simplify hydronic zoning, and up to 16 boilers can be cascaded for larger buildings.
Proper installation requires attention to gas supply, venting, condensate drainage, electrical supply and hydronic connections. The brochure specifies 2″ venting up to 65 feet and 3″ venting up to 150 feet. The boiler uses a 120V AC, 60Hz electrical supply, has a 3/4″ NPT gas connection, and can use existing 1/2″ gas piping up to 24 feet where local code allows. Gas supply and venting must be installed according to applicable codes and manufacturer requirements.
Correct sizing is essential. The right model should be selected from the building's heat-loss calculation, the number of heating zones and any indirect tank for domestic hot water. 4Most Energy can assess the existing system and recommend the appropriate NFB-H model.
Why Install the Navien NFB-H with 4Most Energy?
- 95.0% AFUE condensing efficiency – ENERGY STAR certified.
- Two sizes: NFB-175H (175,000 BTU/h input) and NFB-200H (199,900 BTU/h input).
- Turndown ratio up to 15:1 (13.2:1 on NFB-175H) to reduce cycling and wasted energy.
- Patented stainless steel fire tube heat exchanger – ASME-certified, H-stamped, laser-welded.
- Fully modulating metal-fiber premix burner with dual Venturi for combustion control.
- Built-in powered connections for up to three zone pumps or three zone valves.
- Cascade up to 16 boilers and common-vent up to 8 units.
- 2″ PVC venting up to 65 ft, 3″ up to 150 ft with a Vent Installation Detector (VID) for added safety.
- Natural gas or propane – field conversion kit included (including high-altitude NG).
- Advanced user interface with setup wizard and Quick Dial Wheel; optional NaviLink Wi-Fi control.
| Specification | NFB-175H | NFB-200H |
|---|---|---|
| Model | NFB-175H | NFB-200H |
| Product Type | Heat-only condensing fire tube boiler | |
| Heating Input | 13,300–175,000 BTU/h | 13,300–199,900 BTU/h |
| Heating Capacity | 160,000 BTU/h | 182,000 BTU/h |
| Net AHRI Rating – Water | 139,000 BTU/h | 158,000 BTU/h |
| Efficiency | 95.0% AFUE | |
| Turndown Ratio | 13.2:1 | 15:1 |
| Fuel Type | Natural Gas / Propane convertible | |
| Installation Type | Indoor wall-hung | |
| Venting Type | Forced-draft direct vent | |
| Venting Options | 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 | |
| Gas Connection | 3/4″ NPT | |
| Natural Gas Supply Pressure | 3.5″–10.5″ WC | |
| Propane Supply Pressure | 8.0″–13.0″ WC | |
| Electrical | 120V AC, 60Hz | |
| Maximum Power Consumption | Less than 15 amperes | |
| Heating Supply/Return | 1-1/4″ NPT | |
| Water Pressure | 6–80 PSI | |
| Boiler Water Volume | 4.5 gallons | |
| Dimensions | 17.3″W × 17.3″D × 27.6″H | |
| Boiler Weight | 121 lb | |
| Weight with Water | 148 lb | |
| Heat Exchanger Material | Stainless steel | |
| Casing | Cold-rolled carbon steel | |
| Ignition | Electronic ignition | |
| Zoning | Up to 3 zone pumps or 3 zone valves (built-in) | |
| Cascade | Up to 16 boilers | |
| Vent Clearance | 0″ to combustibles | |
| Model | Heating Input | Heating Capacity | Net AHRI Rating | Recommended Home Size |
|---|---|---|---|---|
| NFB-175H | 13,300–175,000 BTU/h | 160,000 BTU/h | 139,000 BTU/h | Must be determined by heat-loss calculation |
| NFB-200H | 13,300–199,900 BTU/h | 182,000 BTU/h | 158,000 BTU/h | Must be determined by heat-loss calculation |
The Navien NFB-H is built for large homes, multi-zone hydronic systems and light-commercial buildings with a high heating load. Choose the model by heating capacity, not by square footage alone.
- NFB-175H heating capacity: 160,000 BTU/h (net AHRI 139,000 BTU/h)
- NFB-200H heating capacity: 182,000 BTU/h (net AHRI 158,000 BTU/h)
- Net AHRI ratings are based on a piping and pickup allowance of 1.15
Ideal for multiple hydronic heating zones, including in-floor radiant loops, baseboards and radiators, snow-melt and garage zones, and indirect tanks for domestic hot water.
⚙️ Your installer confirms the right size with a heat-loss calculation before installation.
Best Fit ( Size & Applications )
NFB-175H: large homes and multi-zone radiant or baseboard systems.
NFB-200H: higher heat loads, snow-melt and garage zones, and light-commercial buildings.
Need more capacity? NFB-H boilers can be cascaded (up to 16 units).
Pairs with indirect water heaters for domestic hot water.
1. Request Installation Quote Provide information about your existing heating system so the installation requirements can be reviewed.
2. System Sizing Consultation The building heat load and number of zones are evaluated to choose between the NFB-175H and NFB-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 and associated equipment are removed as included in the approved installation scope.
6. Installation & System Connection The NFB-H is wall-mounted and connected to the heating supply and return, zone pumps or valves, indirect tank (if used), 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 boiler is configured with the setup wizard and tested to verify heating operation in every zone.
The Navien NFB-H Series warranty, as stated in the manufacturer’s 2026 brochure, provides different coverage for residential and commercial installations. For single-family residential locations, the heat exchanger is covered for 15 years, parts for 5 years, and labor for 1 year. Commercial installations receive 10 years of heat exchanger coverage, 3 years for parts, and 1 year for labor.
| Warranty Coverage | Residential* | Commercial |
|---|---|---|
| Heat Exchanger | 15 Years | 10 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 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 NFB-175H and NFB-200H?
Both are heat-only condensing boilers in the same cabinet with 95.0% AFUE. The NFB-175H has a heating input of 13,300–175,000 BTU/h (160,000 BTU/h heating capacity). The NFB-200H has 13,300–199,900 BTU/h input (182,000 BTU/h heating capacity) and a higher 15:1 turndown ratio.
Is the Navien NFB-H a combi-boiler?
No. The NFB-H is a heat-only boiler for hydronic space heating. Domestic hot water can be provided by connecting an indirect water heater. If you need heating and hot water from one unit, see the Navien NFC-H combi-boiler.
Which size do I need?
Size is based on the building’s heat-loss calculation, number of zones and any indirect tank load, not square footage alone. 4Most Energy can evaluate the application and recommend the right model.
How efficient is the NFB-H?
Both models are rated at 95.0% AFUE and are ENERGY STAR certified. A turndown ratio of up to 15:1 lets the boiler modulate to match demand and reduces short cycling.
Can the NFB-H work with multiple heating zones?
Yes. The NFB-H has built-in powered connections for up to three zone pumps or three zone valves. For more zones, an optional SmartZone+ pump controller supports up to 6 zone pumps.
Can NFB-H boilers be cascaded?
Yes. Up to 16 NFB-H boilers can be cascaded, and up to 8 can share a common vent, for larger homes and commercial buildings.
Does the NFB-H use a stainless steel heat exchanger?
Yes. Navien’s patented stainless steel fire tube heat exchanger is ASME-certified, H-stamped and manufactured with robotic laser welding.
Can it run on natural gas or propane?
Yes. The NFB-H is field convertible between natural gas and propane, and the conversion kits (including NG high altitude 5,400–10,100 ft) are included. Conversion must follow Navien’s procedures.
What venting does the NFB-H use?
It is an indoor wall-hung, forced-draft direct-vent boiler. Venting can be PVC (including schedule 40), CPVC, polypropylene or stainless steel: 2″ up to 65 ft or 3″ up to 150 ft.
What warranty does the NFB-H have?
For single-family residential locations: 15-year heat exchanger, 5-year parts and 1-year labor. Commercial: 10-year heat exchanger, 3-year parts, 1-year labor. 4Most Energy also includes a 1-year labour warranty on installation.
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