The NHB series of Condensing Heating Boilers contain Navien's advanced burner system, resulting in an AFUE of 95.0% and industry-leading turndown ratios up to 15:1. Other features include:

• Can be installed with 2" PVC venting up to 60 feet, and 1/2" gas pipe up to 40 feet (subject to local codes)
• All units come with a field orifice conversion kit for propane gas operation
• Integrated controls allow for features such as adjustable heat capacity, timed hydronic supply water boost, freeze protection, and more
• Cascading technology allows the boiler to cascade with up to 16 units, and common vent up to 8 units