Navien NFB-C Series 399K BTU – High Efficiency – Condensing Heating Boiler
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The Navien NFB-399C is a wall-hung condensing heating boiler rated at 399,000 BTU/h with 97.5% AFUE, 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, while the direct-vent sealed combustion design 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, operates on standard 120V power and is ASME H stamped, CSA 4.9 certified and ENERGY STAR qualified. Cascade control lets multiple NFB-C boilers stage together for larger plants, and the compact 25-1/10 in. wide by 32-4/5 in. tall cabinet frees valuable mechanical room floor space. Professional installation by a licensed heating contractor is required.
We offer free standard shipping within the United States. Estimated standard delivery time is 3–5 business days. Carrier delays, severe weather, holidays or freight scheduling may affect delivery estimates.
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