Navien · NFB (first generation)
Navien NFB-175
The Navien NFB-175 is a first-generation fire-tube condensing boiler from the discontinued NFB series: 17.5 to 175 MBH heating input, 161 MBH capacity, a 140 MBH net AHRI water rating and 95.0% AFUE, heating-only.
Key figures
- Max input
- 175 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 17.5 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Navien NFB-175 in practice
The NFB-175 is one of the two original NFB fire-tube boilers (NFB-175 and NFB-200) that Navien lists under Discontinued Products on both official sites. The NFB QuickFacts print 17.5–175 MBH heating input with 161 MBH heating capacity, a 140 MBH net AHRI water rating and 95.0% AFUE.
The NFB is a heating-only boiler: it has no domestic hot water production inside the unit, so hot water comes from an indirect tank or a separate appliance and the model's error tables carry no DHW codes. It weighs 115 lb and measures 17.3 W × 17.1 D × 28.9 H in, with 1 1/4" NPT heating supply and return connections, a 3/4" NPT gas connection and 12 – 80 psi hydronic pressure.
The fire-tube heat exchanger is the design Navien carried into the current NFB-H generation, and the QuickFacts list a 10:1 turndown for both models with 2" venting to 60 ft or 3" to 150 ft. Parts and error codes for these first-generation units should be matched to the NFB series documentation, not the NFB-H manual.
Best suited to
- Owners of an existing first-generation NFB boiler looking up its printed ratings
- Comparing the original NFB generation with the current NFB-H line
- Sourcing technical data for an older heating-only Navien boiler
Applicability and support
- Model number
- NFB-175
- Canadian availability
- historical
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Not verified
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Navien. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Heating input, minimum | 17.5 MBH | Per the NFB Series QuickFacts. |
| Heating input, maximum | 175 MBH | Per the NFB Series QuickFacts. |
| Output | ||
| Heating capacity | 161 MBH | DOE test basis, per the NFB Series QuickFacts. |
| Net AHRI water rating | 140 MBH | Net AHRI water rating based on a piping and pickup allowance of 1.15. |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | AFUE per the NFB Series QuickFacts. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler; domestic hot water via an indirect tank or separate appliance | |
| Venting and air | ||
| Venting | 2" or 3" PVC, CPVC, polypropylene; 2" or 3" special gas vent Type BH (Class III A/B/C) | Forced-draft direct vent per the official specifications. |
| Physical and connections | ||
| Weight | 115 lb | As printed in the official document. |
| Width | 17.3 in | |
| Height | 28.9 in | |
| Depth | 17.1 in | |
| Heating connections | 1 1/4" NPT | Supply and return. |
| Gas connection | 3/4" NPT | |
| Operating limits and other | ||
| Fuel | Natural gas or propane | Ratings are the same for natural gas models converted to propane use; field conversion is licensed gas work. |
| Hydronic water pressure | 12 – 80 psi | |
Alerts documented for this model
None documented yet.
Frequently asked questions
What are the ratings of the Navien NFB-175?
The NFB QuickFacts print 17.5–175 MBH heating input, 161 MBH heating capacity, a 140 MBH net AHRI water rating and 95.0% AFUE.
Does the Navien NFB-175 make domestic hot water?
No. The NFB is a heating-only boiler; domestic hot water is supplied by an indirect tank or a separate appliance. That is why the NFB error tables have no DHW codes.
Is the Navien NFB-175 still sold?
No. The NFB series (NFB-175, NFB-200) is on Navien's discontinued-products list; the current heating-only fire-tube line is the NFB-H series (NFB-175H and NFB-200H).
Questions about the Navien NFB-175?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
- Navien Canada — NFB-175 product page (discontinued model downloads) · accessed September 9, 2026
- NFB Series QuickFacts (EN) · accessed September 9, 2026
- NFB Submittal Sheet (EN) · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.