Navien · NFB700-C Commercial Boiler
Navien NFB700-800C
The Navien NFB700-800C is the third size of the floor-standing NFB700-C commercial boiler series: 66 to 799 MBH of input with a 779 MBH heating capacity and a 677 MBH net AHRI water rating at 97.5% thermal efficiency, in the larger 750 lb cabinet.
Key figures
- Max input
- 799 MBH
- Max CSA output
- —
- AFUE
- —
- Min input
- 66 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Navien NFB700-800C in practice
The NFB700-800C fires from 66 to 799 MBH at a printed 97.5% thermal efficiency, with the product page listing a 779 MBH heating capacity and a 677 MBH net AHRI water rating (net figures are based on a piping and pickup allowance of 1.15). It is the first of the two large-frame NFB700-C models, stepping the minimum input from 40 to 66 MBH and the cabinet from the 72.1-inch to the 73.3-inch frame.
The boiler weighs 750 lb dry and 1,059 lb with its 37 gallons of water, measures 23.8 x 73.3 x 33.0 in, and connects on 2 1/2" NPT water and 1 1/4" NPT gas fittings. Venting steps up to 6" PVC, CPVC, approved polypropylene or approved stainless steel (or 6" special gas vent Type BH, Class III A/B/C) in a forced-draft direct-vent arrangement, with the series page stating venting up to 150 ft; the product pages print a 12–160 PSI water pressure range, and the stainless fire-tube heat exchanger sits in a cold-rolled carbon steel casing.
Best suited to
- Commercial hydronic plants whose load calculation lands between 66 and 799 MBH
- Projects whose piping and venting already run at 2 1/2" water and 6" flue sizes
- Mid-size institutional and multi-tenant buildings with a 160 PSI system design
Applicability and support
- Model number
- NFB700-800C
- 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 | ||
| Input, minimum | 66 MBH | Per the product page. |
| Input, maximum | 799 MBH | Per the product page. |
| Output | ||
| Heating capacity | 779 MBH | Per the product page. |
| Net AHRI water rating | 677 MBH | Net AHRI based on a piping and pickup allowance of 1.15, per the product page. |
| Efficiency | ||
| Thermal efficiency | 97.5 % | As printed on the product page (DOE test basis); the page labels the row "Thermal Efficiency", not AFUE. |
| Venting and air | ||
| Venting | 6" PVC, CPVC, approved polypropylene or approved stainless steel, or 6" special gas vent Type BH (Class III A/B/C) | Forced-draft direct vent per the product page; the series page states venting up to 150 ft. |
| Physical and connections | ||
| Weight | 750 lb | 750 lb dry; 1,059 lb with water, per the product page. |
| Width | 23.8 in | |
| Height | 73.3 in | |
| Depth | 33 in | |
| Water content | 37 gal | Per the product page. |
| Heating water connections | 2 1/2" NPT | Per the product page. |
| Gas connection | 1 1/4" NPT | Per the product page. |
| Operating limits and other | ||
| Fuel | Natural gas or propane | Ratings are the same for natural-gas models converted to propane use, per the product page; the series ships with a propane conversion kit. |
| Water pressure rating | 12 – 160 psi | 12–160 PSI water pressure range printed on the NFB700-C product pages. |
| Altitude rating | 10,100 ft | Per the NFB700-C series page. |
Manuals
Alerts documented for this model
None documented yet.
Frequently asked questions
What is the input range of the NFB700-800C?
66 to 799 MBH, per the product page, with a 779 MBH heating capacity and a 677 MBH net AHRI water rating at 97.5% thermal efficiency.
How does the NFB700-800C differ from the NFB700-600C?
The 800C moves to the large frame: 750 lb dry (1,059 lb with water) against 622/843 lb, 37 gallons against 26.5, 2 1/2" NPT water and 1 1/4" NPT gas connections against 2" and 1", and 6" venting against 4". Its minimum input also rises from 40 to 66 MBH.
What venting does the NFB700-800C use?
6" PVC, CPVC, approved polypropylene or approved stainless steel, or 6" special gas vent Type BH (Class III A/B/C), per the product page; the series page states venting up to 150 ft.
Questions about the Navien NFB700-800C?
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 — NFB700-C series · accessed September 9, 2026
- Navien Canada — NFB700-800C product page · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.