Navien NHB-150 Condensing Heating Boiler

The Navien NHB-150 is a residential hydronic condensing boiler designed for space heating applications (radiant floor, baseboard, panel radiators) rather than for domestic hot water. Some installs pair it with a separate indirect water heater tank to provide DHW as well; pure-DHW applications use Navien's NPE tankless series instead. The "150" refers to the 150,000 BTU input rating.

Specs: 150,000 BTU input, AFUE 95% (condensing operation), fully modulating burner (5:1 turndown ratio), stainless steel heat exchanger, PVC venting. Compatible with various hydronic system configurations: low-temperature radiant, conventional baseboard, mixed-temperature multi-zone systems with primary-secondary piping. 10-year warranty on the heat exchanger, 5-year on parts, 1-year on labor.

The NHB-150 is positioned for medium-sized homes (1,800–3,200 sq ft) in cold climates where hydronic space heat is the primary heating system. For larger homes, the NHB-200 (200K BTU) or NHB-300 are the appropriate sizes. The modulating burner with 5:1 turndown means the unit can fire down to 30,000 BTU during low-load conditions, improving efficiency during shoulder-season operation and reducing short-cycling.

Right buyer: a homeowner replacing an aging cast-iron or atmospheric boiler with a high-efficiency replacement, or a new construction install specifying condensing hydronic. The install is plumber/HVAC contractor territory — not DIY. Expect $7,000–$11,000 installed depending on whether the existing hydronic system requires modification.

This is a space-heating product, not a water heater. Listing it in the water-heaters category reflects Navien's combined product line and the install scenarios where homeowners shop boilers and water heaters together. For pure domestic hot water needs, the NPE tankless series is the right Navien product.