Navien NFB-175H
The Navien NFB-175H is a heating-only condensing boiler firing 13.3 to 175 MBH at 95.0% AFUE, with 1 1/4" NPT heating connections and no integrated hot-water production — hot water comes from an external tank.
Key figures
- Max input
- 175 MBH
- Max CSA output
- —
- AFUE
- 95 %
- Min input
- 13.3 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Navien NFB-175H in practice
The NFB-175H is Navien's heating-only condensing boiler for systems that separate the two jobs: it heats the house from 13,300 to 175,000 BTU/h of input at 95.0% AFUE, and domestic hot water is handled by an indirect tank or a separate appliance rather than the boiler itself. Because no DHW happens inside the unit, its error table carries no DHW codes.
Heating connections step up to 1 1/4" NPT and the boiler holds 4.5 USG of water, weighing 121 lb empty and 148 lb with water, per the installation manual. Venting is 2" or 3" with PVC as the default pipe material — approved polypropylene and stainless steel systems are also listed — to 65 or 150 equivalent feet, and system pressure is rated 6 to 80 psi.
Best suited to
- Homes that will pair the boiler with an indirect tank for domestic hot water
- Detached houses whose heat-loss calculation fits under 175 MBH of input
- Owners who want a heating-only boiler with no DHW-side complexity in the control
Applicability and support
- Model number
- NFB-175H
- Canadian availability
- available
- Production status
- current
- 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 | 13.3 MBH | Space-heating input. |
| Heating input, maximum | 175 MBH | Space-heating input. |
| Efficiency | ||
| Efficiency (AFUE) | 95 % | 95.0% AFUE per the installation manual. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler; domestic hot water via an indirect tank or separate appliance | |
| Venting and air | ||
| Venting | PVC, CPVC or approved polypropylene; 2" or 3" | Canada: plastic venting must meet ULC S636 where required. |
| Max. equivalent vent length, 2" | 65 ft | |
| Max. equivalent vent length, 3" | 150 ft | |
| Physical and connections | ||
| Weight | 121 lb | 55 kg; 148 lb (67 kg) with water. |
| Width | 17.3 in | |
| Height | 27.6 in | |
| Depth | 17.3 in | |
| Gas connection | 3/4" NPT | |
| Heating water connections | 1 1/4" NPT | |
| Water content | 4.5 USG | |
| Operating limits and other | ||
| Fuel | Natural gas or propane | Separate Navien ratings per fuel. |
| Altitude rating | 10,100 ft | Per installation manual. |
| System water pressure | 6 – 80 psi | |
Manuals
Alerts documented for this model
Frequently asked questions
Why does the NFB-175H have no DHW error codes?
Because it produces no domestic hot water: the NFB-H is heating-only, so its error tables cover heating and component faults only. DHW comes from an indirect tank or a separate appliance.
What size is the NFB-175H?
It measures 17.3 x 17.3 x 27.6 in and weighs 121 lb empty, or 148 lb with water, per the installation manual.
Can the NFB-175H be vented in PVC?
Yes. The installation manual names PVC as the default vent pipe material, with approved polypropylene and stainless steel vent systems also allowed, up to 65 equivalent feet in 2" or 150 in 3".
Questions about the Navien NFB-175H?
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-H series · accessed September 7, 2026
- NFB-H Installation and Operation Manual (EN) · accessed September 7, 2026
- NFB-H Service Manual, Ver 1.0 (Jan 2021) · Ver 1.0 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.