Description
Navien NFB-399C399,000 BTU/h Condensing Heating Boiler
A wall-hung condensing heating boiler built for light commercial and large residential hydronic systems. Its stainless steel fire tube heat exchanger and 9.6 gallon water capacity deliver stable supply temperatures for baseboard, panel radiator and radiant floor loops.
Direct-vent sealed combustion allows flexible PVC, CPVC or polypropylene venting through a sidewall or roof. The unit runs on natural gas and converts to propane in the field. Cascade control lets multiple NFB-C boilers stage together for larger plants, and the compact cabinet frees valuable mechanical room floor space.
Technical specification
| Type | Condensing heating boiler (heating-only) |
|---|---|
| Input | 399,000 BTU/h |
| Efficiency | 97.5% AFUE |
| Heat exchanger | Stainless steel fire tube |
| Water capacity | 9.6 gallons |
| Venting | Direct-vent sealed combustion, PVC, CPVC or polypropylene, sidewall or roof |
| Fuel | Natural gas, field-convertible to propane |
| Power | Standard 120V |
| Cabinet dimensions | 25-1/10 in. wide × 32-4/5 in. tall, wall-hung |
| Cascade control | Multiple NFB-C boilers stage together for larger plants |
| Certifications | ASME H stamped, CSA 4.9 certified, ENERGY STAR qualified |
| Best suited for | Light commercial and large residential hydronic systems |
Installation notice
Professional installation by a licensed heating contractor is required.
Navien NFB-399C boiler. Follow the installation manual, local gas and plumbing codes, and manufacturer instructions.